L,11 fs'A iTL-A3 fiction of VHF/VHF aerial systems€¦ · KR250 Kenpro Lightweight 1-1r mast 46.00 1370 Morse Tutor 950213 Colorotor (Med. VHF) 56.60 AD270 Indoor Active Filter (inc

0113 L,11 _fs'A

The facts andfiction ofVHF/VHFaerialsystems

sceiversfor 10m coverage

VE0411a38the C5800.How good, howStandard? Full usertest and lab report

The Far East'snew baby visits thecleaners

ER A4IM8getting the most outof your transceiver

iTL-A3

Same -day dispatchon orders received bymidday, with deliveryby Securicor or

Insured Post at our option.Mail order terms are carriage -free to

mainland UK on orders £100.00 or over. £1.00 peritem please towards carriage/packing on ordersunder £100.00.

AMATEUR RADIO .1CHANGE

WELZ PRODUCTS

NEW RIGS FOR OLDThis selection from our full stock

list only hints at the enormousrange of equipment we carry by allthe leading manufacturers. Noquestion of pushing the make wehappen to import -or have"handed" to us. At A R E, whetherin London or St Helens, weencourage you to try out thevarious makes and models side byside and see which is right for you.It's your money, so it's your choice,and that goes for Brenda's coffeetoo...black or white, "with" or"without:'

Our customers know that we alsohandle a very wide selection ofsecondhand gear, all types and allprices, because taking your old rigin part exchange is not somethingwe do as a rather grudging favour.On the contrary, it is a perfectlynormal aspect of the way we dobusiness. So, if you are thinking of atransformation scene in yourshack for '83, phone or call in, orsee us at major rallies throughoutthe summer, and let's see if we cando a deal that will keep everybodyhappy...you with your new rig,and the chap who buys the old one!

FT980CAT NEW all -mode transceiver withAM/CW/FM/SSB/AFSK P.O.A.

FT102 160-10M 9 -Band Trans. NEW 775.00FT ONE Gen. Coverage Trans NEW 1345.00FT790R 70cm all -mode portable NEW 309.00FTIOIZFM 160-10m 9 -Band Transceiver 590.00FTIOJZOFM 160-10m 9 -Band Transceiver 665.00FC902 9 -Band atu, swr/pwr etc 135.00FL2100Z 9 -Band 1200W linear 445.00FT77 8 -Band solid state 100W 469.00FP707 230 volts AC power supply 125.00FC707 Aerial tuner (unbalanced only) 65.00FR67700 SSB/AM/FM recvr. dig. readout 299.00MEM7700 Memory unit for above 90.00

CONVERTERS FOR ABOVEFRV7700A 118-150MHz 69.75FRV77038 50-60MHz & 118-150MHz 75.50FRV77000 140-170MHz 65.95FRV7700D 70-80MHz & 118-150MHz 72.45

FRT7700 Receiver aerial tuner 37.85FT480R 2m all -mode transceiver .365.00FT780R 70cm all -mode transceiver .39900FT290RD SPECIAL 1983 version with

ARE mods and 3SK87 f/end 259.00FT208R 2m synthesized portable FM 199.00FT7013R 70cm hand-held 209.00

ICONIC740 Multimode H.F. trans. NEW 695.00IC720A HF transceiver and gen. cov. rec. 849.00IC730 HF mobile transceiver 8 -band 599.00ICR70 New multimode receiver 475.00

IC290HIC2E

IC4E

2m multimode mobile 25W2m FM synthesised handheld70cm handheld

389.00159.00169.00

TRIO-KENW000TS430STS930TSI3OSR600

1.8-160mHz 20-200w-1 kw IPWR/SWR Meter 69.951.8-500mHz 20-299w-1kwPWR/SWR Meter 97.00

SP400 130-500mHz 5-20-150w ISP600 1.8-500mHz 20-100-2kwPWR/SWR Meter 69.95

PWR/SWR Meter 97.00SP15M 1.8-160mHz 5-20-200w PWR/SWRSCANNING RECEIVERS

35.00A R E COMMUNICATIONS SP45M 130m-47OmHz PWR/SWR Meter 51.00

AR3000 720 channel synthesised air SP -10X Compact version of SP15M

Meter

24.45 Iband receiver 99.99 SP250 1.8-60mHz 20-200-2kw 49.50FAIRMATE SP350 1.8-500mHz 5-20-2kw

AS32320 VHF/UHF scanning receiver,air vend/military/policece 139.00

SP380 Compact version of SP3001200 watts max) 49.00

ATC720F D K AC38 3.5-30mHz ATU 400w PEP 18 bands) 6500720 channel air band handheld 129.00 CT15A 15/50w dummy load. IPL259) 795

AM/FM 259.00 250mHz (S0239) 35.50 IJ I L CT15N 15/50w dummy load. l'N' plug) 13.9516 channel memory, synthesised CTI50 150/400w dummy load. Rated

MAXIMAL -MICKEY CT303 300/1kw dummy load

I8 channel memory. 70-80MHz, 250mHz (S02391 49.50140-176MHz, synthesised 99.00 CTO3N 3w dummy load 1.3GHzBEARCAT I'N' socket) 30.0020 channel memory. AM/FM synth 249.00 :.:H20A 2 way coax switch 1kw

900mHz IS02391 17.95

THETA9000E RTTY/CW/ASCII, Tx/Rx 66900 1.3GHz ('N' socket) 31.95 ITONG CH2ON 2 way coax switch 1kw

THETA550 Rx only 299.00 TP05X 50-500mHz power meter with load 13.95

AMPLIFIERS TTPF.2205AG 50-500mHz 25w power meter with load 17.50

2M -50W 144MHz 30-50W129.0069

CA35A Static discharge protector. DC 500mHz30-1500mHz power meter with load 13900UC70 430MHz 55W -preamp 159.00

216-103W 144MHz 100W -preamp300w (S0239) 10.75

MR 15(kN 144MHz 130-150W - preamp 169.00 CA23N Static discharge protector. DC 1500mHz

M1.131171.=1.111111=1MR 250M/ 144MHz 250W - preamp 32500 300w (*PI' socket) 1210

TeleReader CWR685 RTTY/CW/ASCII

SX200N

MK4003

BC20/20

Gen. coverage multi -modeGen. coverage trans.8 -Band 200W pepGen. coverage receiver

TASCO

NEW 699.00NEW P.OA.

469.00235.00

769.00 PC1 Gen. Cov. Converter HF on 2m 137.42

TeleReader CWR670E As above Rx onlyTeleReader CWR61OE Basic unit

219.00 VLF Very Low Frequency Converterun 00 FL1 Frequency Agile Converter

' FL2 Multi -mode Audio Filter 69.70NEW 129.37FL3 FL2 with auto notch

n79:3905 I

SA450 S0239 connectors, 1 in, 2 out 975 (Trio or Yaesu plugASP Auto R.F. Speech Clipper

RFC/M R.F. Speech Clipper Module 29.90ISA450N N -type connectors, 1 in. 2 out 12.75 D75 Manually controlled R.F.

ROTATORSSpeech clipper 56.35

112.90/89.70

KR250 Kenpro Lightweight 1-1r mast 46.00 1370 Morse Tutor950213 Colorotor (Med. VHF) 56.60 AD270 Indoor Active Filter (inc. PSU)

56.35

54KR 400RC Kenpro-inc. lower clamps P 0A. 40370 Outdoor Active Filter linc. PSUI 71.30137.42KR =RC Kenpro-inc. lower clamps

Keyer Paddle (black base)BENCHER

P OA. MK Keyboard morse sender

35.8/RFA Wideband preamplifier

PTS1 Programmable tone squelch system(two units) 45.99 I

33.92

Keyer Paddle (chrome base) muTek43.7292.00 SLNA7Os 70MHz switched preamp. 33.90Keyer Paddle (gold plated)

Balun 3 5-30MHz for dipolesBalun 14-30MHz for beam ant 1725 SLNA7Oub Unboxed SLNA7Ou

SLNA7144s 144MHz switched preamp

2030 I12.41

15.00 SLNAICIti 70MHz unswitched preamp.

(now 0.9dB nf typical)) 33.90

and fet headHead set mic with control box

29.00 SLNA145sb Optimised preamp forSLNA144ub Unboxed SLNA144u

203612.41

SLNA144u 144MHz unswitched preamp.

Headphone unit, fet mic with FT29ORDcontrol box 39.00 131.NA432ub 1.3dB nf sub -min 432MHz preamNp7....2132.4953

Mobile speaker and messagepad, visor mount 16.25 GLNA432u-1 432MHz gasfet unswitched

IFlexible neck clip mic with TLNA432s 432MHz bipolar switched preamp. 54.9021.95 TLNA432u 432MHz bipolar unswitched preamp.26.40control box

TLNA432ub Unboxed TLNA432u 16.50

12/6A Power supply, 13.8V. 6 amp,BNOS ELECTRONICS GLNA432u-2 0.65dB nf/13dB gain

HDRA95u-I 1.5dB nf/8.5dB gain high51.: Ipreamp. 0.8dB of/13d8 gain

48.30 dynamic range Band II preampfully protected(input intercept - 22dBm) 29.9012/124 Power supply, 13.8V. 12 amp.

12/244 Power supply, 13.8V. 25 amp.125.45 81313A500u 20-500MHz broadband high

(input intercept - 16dBm) 29.90 I66.40 HDRA95u-2 11.5dB gain variantfully protected

fully protecteddynamic range preamp.12/404 Power supply, 13.8V. 40 amp.

225.40 Xl3PF700ub Band IV -V bandpass tvi filterfully protectedPPSU012 12v (nominal) mains psu for

BBBA 500u and BBBA 860uRPCE125lub IC21 1/251E replacement front-

end board

ANTENNA SWITCHES

ADONIS MICROPH I NES

PS15 Power supply for 720A 109.00 VHF Wavemeter 130 450MHzIC25IE 2m multimode base station 539.00 Morse Tutor

SP200

SP300

By 1BY 2BY 3ZA IAZA 2A

202HD

202HM

202S

MS10

DRAE

FULLY PROTECTED POWER SUPPLIES4 amp 30.75 6 amp 49.00

12 amp 74.00 24 amp 105.00

27.5049.00

26.40295

695

69.90

L 230 2m RF amp. 3W in/30W outELH720EMR400

mi NE NE EN um373 UXBRIDGE ROAD, ACTON, LONDON W3 9RHTel: 01-992 5765/6/7 Just 500 yards east of Ealing Common stationon the District and Piccadilly Lines, and 207 bus stops outside.

CREDIT CARD SALES BY TELEPHONELICENSED CREDIT BROKERS * Ask for writtenquotation on HP terms Also interest -free terms with50% deposit.

BARCLAYCARD

ALINCO

70cm RF amp 1W in/10W out 59.00 IRotator - heavy duty

136 GLADSTONE STREET, ST HELENS, MERSEYSIDETel: 0744 53157 Our North West branch run by Peter (G4 KKNI,just around the corner from the Rugby Ground.Closed Wednesday at Acton and Monday at St Helens, butuse our 24 -hour Ansafone service at either shop

All prices include VAT and are correct as we go to pressHowever, we reserve the right to vary them if forced to do soby the time this advertisement appears. Phone for up-to-date

information. or send 50p for our full Stock List

EditorFrank Ogden G4JST

Assistant EditorRichard Lamont G4DYA

Advertisement ManagerNeil Terry

Classified SalesSally A. Collins

Managing DirectorT.J. Connell

Published by:Argus Specialist Publications Ltd.,145 Charing Cross Road,London WC2H OEE.Telephone: 01-437 1002.

Distributed by:SM Distribution Ltd.

Printed by:Q. B. Ltd.

Subscription Rate:UK £12.900/Seas Sur: £13.250/Seas Air f2.5.80Ham Radio Today,Sub Dept.,513 London Road,Thornton Heath,Surrey,CR4 6AR.

Ham Radio Today is normally published onthe first Friday in the month precedingcover date. The contents of this publicationincluding all articles, designs, plans, draw-ings and programs and all copyright andother intellectual property rights thereinbelong to Argus Specialist PublicationsLimited. All rights conferred by theLaw ofCopyright and other intellectual propertyrights and by virtue of international copy-right conventions are specifically reservedto Argus Specialist Publications Limitedand any reproduction requires the priorwritten consent of the Company. © 1983Argus Specialist Publications Ltd. All reas-onable care is taken in the -preparation ofthe magazine contents, but the- publisherscannot be held legally responsible for er-rors. Where mistakes do occur, a correctionwill normally by published as soon as possi-ble afterwards. All prices and data con-tained in advertisements are accepted by usin good faith as correct at time of going topress. Neither the advertisers nor the pub-lishers can be held responsible, however,for any variation affecting price or avail-ability which may occur after the publi-cation has closed for press.

CONTENTS VOLUME ONE NO. 6 JUNE 1983

REGULAR COLUMNSLETTERS 4You write and we comment

RADIO TODAY 6Is the Ministry of Defence going to build a British woodpecker? Plus the rest of the news

RADIO YESTERDAY 26Jack Hum G5UM looks at amateur radio in the Twenties

TECHNICALITIES 51Wideband transformer design covered this month. We offer a CAD program for the Spectrum

RADIO TOMORROW 54Your at -a -glance diary of forthcoming amateur radio events

NEW PRODUCTS 56

CONSTRUCTIONELEVEN TO TEN 13Bored with CB? Convert your set to 10 metres with our practical guide

A SIMPLE AMATEUR TELEVISION STATION 48Adding a keyboard generator

FEATURESTHE FACTS AND FICTION OF VHF/UHF AERIALS 9Open your wallet where it counts. G4JST's incisive guide

TAKING TO THE AIR 24A tale of one man's struggle with the airwaves

TAKING APART THE FT -101 28Part 2 of the definitive servicing guide by G3LLL

G LINE FOR THE GIGAHERTZ MEN 33The single wire surface waveguide is a cheap possibility for microwaves

A PLAIN MAN'S GUIDE TO MASTS AND TOWERS 42Part 5: planting a tower in the concrete

DRIVING LESSON 45Get the most out of your box by knowing the functions behind the controls

REVIEWSTRIO/KENWOOD TS -430S HF TRANSCEIVER 57

STANDARD C5800 CW/SSB/FM 2M TRANSCEIVER 64

FREE! FT -101E PULLOUT CIRCUIT DIAGRAM 37-40

NEXT MONTH IN HAM RADIO TODAY 41

HAM RADIO TODAY MORSE COURSE 54EMPORIUM GUIDE 70ADVERTISERS' INDEX 71

CLASSIFIED 72

HAM RADIO TODAY JUNE 1983 3

LETTERSAMERICAN WOODPECKEROM, Enclosed you will find copies of anarticle from INTERAVIA' a technicalmagazine on the subject of anotherMegawatt over -the -horizon HF Radar systemoperating on the backscatter principle. Ifthey are looking for backscatter back inMaine, USA, just think what we will begetting as forward scatter here in Europe! Ihave not yet been graced with a reply fromCol. A Lee Snyder and probably have beenput on computer for commenting on theirsystem and branded as an undesireable.That may be, but I would like maximumpublicity in the amateur press on thesubject. Who do these people think theyare, grabbing chunks of the HF spectrumand polluting it with Megawatt HF pulsetransmissions? We have had enough withthe Crimean Cackler, though that hasabated very much lately, why?

DES WALSH E15CD

This set the alarm bells going here at HRT,and we've been asking the US Air Force(who are developing the system) sometough questions. The answers are on theRadio Today page - Ed.

SYNTHESISED HF TRANSCEIVERSir, I wish to congratulate you on yourpublication of your articles on theSynthesised HF Transceiver, an excellentproject. Could you please tell me where thecores T37-6 and T37-12 specified for L 1, 2 Sr3 in the VCO can be obtained from and alsothe approximate inductance of these coils.Do you know when PCBs will be availablefor this project?

S NIEWIADOMSKI

The cores in question can be purchasedfrom Ambit International, 200North ServiceRoad, Brentwood, Essex. The approximateinductance of the cores 06 oil, 0.1612H,4002H. The precise values are not criticalsince the VCO circuitry will compensate. Aconsiderable degree of range overlap wasdesigned in.

As for PCBs, we are not going toproduce a set for the project as it stands.The transceiver was built at least 18 monthsbefore Ham Radio Today was ever thoughtof and the documentation which we have todesign the boards is insufficient. However,don't despair. We are producing a mark 2version of the transceiver which will offerenhanced performance, all modes andfacilities such as a noise blanker that reallyworks. I have mooted the design already inour Technicalities column and a series ofconstructional features will follow, possiblystarting in July. We will offer a guaranteed

supply of ready made PCBs kits ofcomponents and a ready made case. Weanticipate that our new all mode, all band,transceiver would cost in the region of .£250in its basic form, and outperform nearly allthe commercial gear currently available -Ed.

PLUMBING THE DEPTHSFrank, As one of those illegal SSB CB usersso often slagged by Ham and UK FM I amsick of reading in your very good andinteresting mag about piggies - that isHam OP's - blaming us for jammingrepeater stations and other nasty things.

I have the equipment (mobile) withwhich to jam - disrupt - and do the nastythings we are blamed for, but my onlyinterest in (Piggy) bands is to listen andlearn, not to use for transmission.

Many (Piggies) use SSB and UK FM.Some who have been on the Ham bands formany years, at least two of them, both oldhands, have admitted to having jammed therepeaters on 2m.

Myself and several friends who earwighave had a meeting on the subject. We areso fed up with being hounded by the HomeOffice - RSGB, we are thinking of doingwhat we are blamed for, so for the sake ofpeace on the airways, cool your (Piggies)and we will not cool down a bit. We expectsome blame. We could, but we do not wishto take the RAE.

And one thing in our favour. We knowwhere most of you live, but you do not knowus. Most of your addresses are in the 83Ham Year Book.

So remember to your Ham readers,leave us alone, and we will leave you alone.

I am not being offensive, just trying tostate our case. Chow from SSB to Ham.May there be peace between us.

SSB CB USERDORSET

Oink - Ed.

WOODEN STAKESHRT, Really! You only print letters withcomments like; "It's becoming anotherwaveband for CB'ers" (re. 2rn), to provoke alittle controversy. I'd like to ask BrianPatchett, who seems to be judging 2m on acursory glance at FM mobile operation,where on CB can you get QRO operation,SSB, CW, RTTY, satellite, choice ofantenna, etc. etc. etc? 2M is a properamateur band, if you take the trouble to useit as such.

Martin Smith's reference to theconfining licenses to over 18's. When I hearopinions like that, I reach for the garlic andwooden stakes! This sort of retrograde idea,

Please address correspondenceto:Frank Ogden G4JSTHam Radio Today,145 Charing Cross Rd,London WC2 OEE.

coupled with the unfortunate experiences ofyoung J. Pelham, indicate to me that thereal problems regarding relations betweenoperators within the UK stem from snobberyand intolerance, from those old enough toknow better!

I wonder, for example, who was thefirst person to sign a letter and to appendhis callsign to his signature? He started atrend which most of us follow, these days;but when you think of it, adding a callsignbehind your name, as if it were a universitydegree, or a fellowship of some augustsociety or institution, is a little pretentious.A callsign belongs to a station, and is usedby whoever is licensed to use the station. If Ivisit my friend's house and use equipment, Iuse his call sign, not mine/A! But this is onlya small point, so let it pass, except for theproviso that I will not be putting my callsignafter my signature!

r

To end on a lighter (?) note, with aword to Tony Bailey, don't joke about TVI-stricken neighbours dismantling an antenna,instead of knocking on the door of thestation. A friend of mine had this rottentrick pulled on him, and he blew everysingle transistor in his 101!

PAUL THOMPSON

SMALL NIGGLEOM, I have bought each copy of yourmagazine since you started, and I willprobably continue to do so because I thinkthe level of its contents is pitched aboutright for the large majority of readers whodo not appreciate the highly professionallevel of most articles in Radcom.

Just one small niggle - I have notbeen able to find the results of thecompetition in the January issue, which Iwould expect to have been published beforenow. If I have overlooked it please let meknow the issue and page in which itappears, or explain why it has notappeared.

JOHN WINDCOMBE G62H

The answers you want appear (by aremarkable trick of fate) right here! Theyare: B,B,C,C,B,A,B,B,D,B,E,D,C,C in thatorder - Ed.

PLAIN SPEAKINGSir, Help! I'm beginning to think I'm uniqueor thick or something.

You see, my problem is that I want tobuild my own equipment for 70tms,microwave etc. but, and it's a big but, Iserved my apprenticeship as a toolmakerand not as an electronics engineer.

I've always been interested in radio but

4 HAM RADIO TODAY JUNE 1983

until I studied for the RAE my knowledge ofelectonics was confined to wiring a plug,now at least I understand basics.

Can we have more projects withpeople like me in mind, people who don'tunderstand properly how to use test andalignment equipment, and written in alanguage we understand.

So please think of me and all the otherslike me who want to enjoy our hobby to thefull and carry on as you have started in yourexcellent magazine (the best on the marketin my humble opinion) and simplify ratherthan mystify.

R K BAINBRIDGE G6HHV

RIFTS?As one of your many EI readers, I would notlike, or indeed be competent, to commenton your allegations of rifts in the UKbetween Class A and B licensees. Suffice tosay, when setting out for my ticket, Ipersonally can state I got nothing but help,encouragement, and patience from both Aand B licensees, and I might add someSWLs.

Perhaps some of your newer amateursmay not be aware of some of the differencesin regulations between the UK and EI.

A Class B licensee on passing his/herCW (similar test to UK) gets a class A callsign. For the first twelve months no phone ispermitted on HF. The operator is confinedto CW 25 watts on 20m and 40m. After thisperiod applications may be made for allbands, phone and CW. All EI Class B

callsigns have three letters ending in B, ieEI8AMB. (My old call sign).

The minimum age for holding eitherlicence is 16 years.

As an unashamed 2m DXer, and chaserof squares, may I respectfully ask all newer,and some older, stations to please put QTHlocator references on all cards that theymight be good enough to send.

In conclusion, I would like to add thatall QSOs to this station whether A or B willget a "Cead Mile Failte".

TONY BAKER EI6EW

POSITIVE VETTINGSir, The purpose of this letter is twofold.First, may I congratulate you on anexcellent magazine. I especially liked the 80metre QRP TX/RX - very impressive.Perhaps we could have a series of them forother bands (I fully intend to build this one,as soon as I can raise the money!)

Secondly, I would like to discuss theHome Office's decision to want 'positiveindentification' when one is taking the CWtest, ie. something like a passport, or similardocument. However, not all of us possess apassport; so are we expected to go straightout and pay EX for one, just to take themorse test (which we don't have to goabroad for)?

I find this decision totally ridiculous,yet at the same time realise the HomeOffice's predicament. I think that alllicensed radio amateurs should be issued

with an identity card containing theirphotograph and signature rather than anamateurish (and in my case, a photocopied)copy of licensing conditions which is writtenon in Biro! How on earth do we expectsuspicious policemen etc. to believe wehave a legal right to use what he considersillegal equipment! Which of course wemight promptly get arrested for!

DAIMON TILLEY G6PRY (age 16)

Modifying the DSB83 for the 1.8MHz bandis quite straightforward; however at 7MHzthe VFO may not be stable enough - Ed.

DUMMY LOAD CALLSIGNSSir, I wish to clarify the position regardingpre-war artificial aerial licences, as thestatements made by G8PTH in his article'Radio Yesterday' in your March issue aremisleading.

Artificial aerial callsigns consisted of thenumeral '2' followed by three letters, with no'G' prefix. When licences were re -issued in1946, holders of AA callsigns were grantedfull radiating facilities providing they passedthe Morse test. They were then licensedunder their previous artificial aerial callsign,with the prefix "G" added.

Incidentally, not all artificial aerialcallsigns were issued in alphabeticalsequence; I can recall that a station in the2C-- series was licensed some time before mylicence was issued.

N G HYDE G2AIH

SARCI AW ARO

[ LaPM COMPONENTS LTD. VALVE & COMPONENTS SPECIALISTS

SELECTRON HOUSE. WROTHAM ROAD, MEOPHAM GREEN, MEOPHAM, KENT

PHONE 0474 813225. TELEX 966371 PM COMPNEW BRANDED VALVES087 11.50134 14.95293 6.60900 11.50

1148,480.00

CC807 1.9CF 80 0.7CF82 0.CF86 1.7CF806 10.2

AF91 0.45 CH3 2..AF96 0.65 CH35 1.

DET22 28.00 CH42 1.'ET24 35.00 CH81 0.

DF91 0.70 CH84 0.6F92 OM CL80 0.F96K91K92K96

0.650.901.202.50

CL82 0.6CL84 0.7CL86 0.7CLL800

1.92 0.60 16.9L96 2.50 F37A 2.LS10 8.00 F39 1.LS16 10.00 F42 3.M160 2.76 F55 2.2586/87 0.65 F80 0.55802 0.72 183 3.

80CC 21.60 F85 0.8OCF 7.00 F86 0.9'80F 13.50 F89 0.881CC 3.50 F91 1.282 CC 3.50 F92 2.5083CC83F86C88C88CC130L180F182CC81,3F

3.503.509.506.002.60

14.506.509.00

16.00

193 0.89F94 0.5F183 0.6F184 0.6F804S 9.85806S 9.8H90 0.7K90 0.7 .

E L3.1 1.95AB C80 0.85 51341Mullard

F42 1.20 3.50891 0.52 L36 1.50BC81 0.85 L38 8.00BC91 0.75 L82 0.58BF80 0.50 L84 0.69C80/0 6.00 185 4.50C90 0.70 L86 0.85CC81 0.85 L90 1.25CC82 0.65 L360 7.99CC82 Ptolips 1519 5.50

1.10 M80 0.70CC83 0.85 M81 0.70CC85CC88CC91

ECC804

0.600.752.000.60

M84 1.10M85 1.10M87 1.1Fel 1.1

4

EY84 6.95E586/87 0.50EY88 0.55EZ80 0.60EZ81 0.60EZ90 0.9601/371K

.00G55/1K

390.00

GS10C 12.00GXU50 12.50GY501 1.20GZ30 1.00GZ32 1.000233 4.50GZ34 2.15GZ37 4.50KT61 3.608166 USA

6.95KT86 UK 9.95KT77 9.50KT88 USA

7.95KT88 UK

12.50KTW61 2.00M8079 6.00M8083 3.25M8100 2.85M8137 5.50M8162 5.50ME 1400 4.00N78 14.950A2 Si:PC86 0.80PC88 0.75PC92 1.20PC97 1.10PC900 0.75PCF80 0.65PCF82 0.60PCF86 1.20PCF200 1.80PCF201 1.80PCF801 1.35PCF802 0.60PCF805 1.25PCF808 1.25PCH200 1.10PCL82 0.60PCL83 2.50

PCL84 0.85PCL85 0.80PCL86 0.85PCL805 0.90PD500 3.50PFL200 1.26PL36 0.95PL8IA 0.72P L84 0.65P L500 0.95PL504 0.96PL508 1.9551509 4.86PL519 4.96PL802 4.95PY88 0.82555004 1.79P5800 0.79PY801 0.79001/02-6

12.750C11/03- 10

5.5000V03 -20A

16.5000V06 -40A

19.00OS 1 50/45

7.00051200 3.950S1209 2.00051212 3.2001/03-12 3.50U19 11.95UCH81 0.66UCLB2 0.80UF8O 0.80UL84 0.85511020 29.00Z759 19.55ZM1001 5.001X2B 1.152D21 0.952K25 24.954CX2508

37.504CX350A

63.754X150A 18.955U4G 0.755U4G8 2.505V4G 0.755Z4G 0.856A87 0.606A88 0.666AC7 2.00

6AF4A 2.50'6AG7 1.956AH6 1.506AJ7 2.006AK6 2.006AL5 0.526AM4 3.256AM5 6.006AN5 3.956405 1.206AS5 1.505AS7G 7.506AT6 0.756AU6 0.556AV6 0.726AW8A 2996846 0.696BA7 4.5068A8A 3.5068E6 0.726606 1.006E1116 1.9568J6 1.2068N7 4.5068N8 2.756887 4.156EI884 2.166557 4.5068W6 5.35BBZ6 2.006C4 0.806CH6 10.356C16 3.506EAB 2.506560 2.006528 1.25BGHEIA 0.8060(6 2,006H6 1.356J5 1.956J5G 0.756J6 0.556J86 3.956JS6C 3.506K D6 4.506L6GC 2.506160T 1.156U8 0.60656GT 0.8068501 0.50787 1.40757 3.0011E2 18.5012AE6 0.8512AGE1 1.6012AT6 0.59

12ATTIVA2.50

12AU6 1.5012AU7 0.5612AV6 0.8012AX] 0.65I2AX7WA

12A57 1:8812AZ7A 1.9512BA6 1.50128E6 1.05128117 1.5012816 0.70128Y7A 2.7512E1 17.9512GN7 3.9512HG7A 3.9530512 1.10408D6 4 5038HE / 4.5075C1 1.3585A1 6.608542 2.0090CG 13.1592AG 11.8592AV 11.8515082 3.95150C4 2.15807 1.50811A 12.95813 18.50833A 115.005642 9.505651567568705696574957515814A5842596560606080614686883670257027A71997247736074757591A866A

3.203.503.503.502.3.65003.256.502.251.506.765.65

13.952.504.853.202.007.505.003.953.95

INTEGRATEDCIRCUITS

AN2140AN240LA4400LA4422LC7120LC7130LC7131LC7137MB3712MC1330PML23113SL901BSL9178SN76003NSN76013NSN76023NSN76033NSN7613 INSN76660NSN76686NTAA550TAA6618TA 7061APTA7120TA7130TA7204TA7205APTA7222TA7310TBA1205TBA520C1TBA530TBA540TBA5500TBA800T8A8105TBA9200TDA1004ATDA I 170TDA 1 190TDA1327TD41412TD42020TDA2030TDA2532T042540TDA2590TDA2600TDA2811AUPC566HUPC575C2UPC100IHUPC1025

2.502.804.152.503.253.505.505.502.000.761.754.556.861.951.961.951.991.300.800.700.251.203.951.651.602.151.501.801.800.701.101.101.251.450.891.351.662.201.952.161.700.852.452.801.951.252.953.501.962.952.752.502.50

SEMICONDUCTORS85199 0.14 11529 0.4085200 0.40 TIP29C 0.4285258 0.28 TIP30C 0.43

AC128 0.20 C172 0.10 BF259 0.28 TIP31C 0.42AC14IK 0.34 C173B 0.10 EIF336 0.34 TIP32C 0.42AC176 0.22 C182 0.10 BFX29 0.30 TIP41C 0.46AC176K 0.31 C183 0.10 85884 0.26 TIP42C 0.47AC187 0.25 C184LA0.09 8FX85 0.32 TIP47 0.55AC187K 0.28 0212 0.09 SFX86 0.30 TIP2955 0.80AC188 0.25 C2 1 2L 0.09 BFX88 0.26 9153055 0.55AD149 0.70 0213 0.09 85550 0.21 TIS91 0.20AD181 0.39 02131 0.09 BFY51 0.21 2N3054 0.59A0161/2 0.90 C237 0.10 BFY52 0.25 2N3055 0.52AD162 0.39 C238 0.09 BFY90 0.77 2N3702 0.12AF 124 0.34 C307 0.09 8T106 1.22 2N3704 0.12AF 125 0.35 0327 0.10 87 108 1.22 2N3705 0.12AF 126 0.32 0461 0.35 87116 1.20 2913708 0.12AF127 0.32 C478 0.20 BU105 1.22 2N5294 0.42AF139 0.40 C547 0.10 BU 1 08 1.69 2N5296 0.48AF239 0.42AU106 2.00AU107 1.75

C548 0.10C549A 0.06C557 0.09

80124 1.0080126 1.60BU205 1.30

265496 0.6525A715 0.952SC495 0.80

AU 1 10 2.00 C558 0.10 8U208 1.39 2SC496 0.80AU I 13 2.95 0131 0.32 80208A 1.62 2SC1096 0.80BC107 0.10 D132 0.35 81.1326A 1.42 2SC1173 1.15BC108 0.10 0133 0.40 8U526 1.90 2SC 1 306 1.00BC1098 0.12 0135 0.30 MRF450A 2SC1307 1.50BC140 0.31 0136 0.30 11.50 2SC1449 0.80BC141 0.25 0137 0.32 MRF453 2SC1678 1.25BC142 0.21 0138 0.30 15.50 2SC1945 2.10BC143 0.24 0139 0.32 ARF454 2SC1953 0.95BC147 0.09 0140 0.30 23.50 2SC1957 0.90BC148 0.09 5179 0.34 MR5475 2.50 2SC1969 1.958C149 0.09 F180 0.29 MRF477 2SC2028 1.15BC157 0.12 F183 0.29 10.00 2SC2029 1.95BC158 0.09 5194 0.11 0071 0.40 2SC2078 1.45BC159 0.09 F196 0.11 820088 1.70 2SC20910.858C160 0.28 5197 0.11 820108 1.70 2SC2314 0.90BC1708 0.15 F198 0.19 R2540 2.48 2S0234 0.50

Many other items /mu a.Please phone send list for quote

Goods normally despatched within 24 hours

CALLERS WELCOME* Entrance on A227 50yds * HoursSouth of Meopham GreenExport enquiries welcome Mon. -Fri. 9.30-5.30

P. & P. 50p. Please add V.A.T. at 15%* 24 -HOUR ANSAPHONE SERVICE *


RADIOTOD

News about amateur radio compiled by Richard Lamont G4DYA

WesternWoodpeckers?Britain and the USA areboth developing HFover -the -horizon radarsystems for militaryapplications, operatingin the 5-28MHz range.The American system, called ConusOTH-B, has already been operating inexperimental form for three years. (The 'B'stands for Backscatter.) It consists of atransmitter site at the Moscow Air ForceStation, Maine, North-East USA, and aseparate receiving station 110 milesaway at the Columbus Falls Air ForceStation, also in Maine.

The system is intended to providelong-range detection of 'air -breathing'threats, ie. bombers and cruise missilesaimed at North America. It would providethe US with an early warning period ofhours, rather than the minutes offered byconventional UHF radars.

In spite of the enormous transmitterpowers involved (100 Megawatts ERP forthe prototype alone) the USAF is claimingthat interference is unlikely, because thesystem would only operate on emptychannels in the fixed and broadcastingbands, and that certain frequenciesincluding amateur bands would beconsidered as 'guarded frequencies' andnot used at all. A spokesman for theUSAF's Electronic Systems Division(which is developing Con us) admits "TheAir Force is not denying the possibilitiesof interference. The signal is awfullysmall. One of the ham publications hascompared this to the Woodpecker. Thereis no comparison. This system is verysophisticated, whereas the Woodpeckerseems to use a brute force approach".

The present system was built byGeneral Electric, which won the contractin 1975. Testing began in June 1980.This first installation is now beingupgraded, and it will be the firstoperational radar, covering the Eastern

approaches to the USA. The USAF plansto build a second site in the West over thenext four years or so. Longer term plansexist for a third radar in the South.

British OTH radar

The American Conus system usesskywave propagation to achieve itsrange. The British defence establishmentis working on a surface wave OTH radarsystem, operating in the same 5-28MHzfrequency range as Conus. According tothe Ministry of Defence, the British systemis not intended to detect incomingnuclear bombers and missiles. The MoD,not surprisingly, refuse to say what thesystem is for. They did, however, divulgethat the system has a pulse repetitionfrequency of a fraction of a Hertz, and issupposed to have a 'very long range'.

According to an American OTHradar consultant, the only place whereyou could expect very long rangepropagation of an HF surface wave is atsea, where the salt water provides a lowresistance ground plane. A ship -basedHF surface wave radar could be used to

give warning of both enemy ships andsea -skimming missiles such as the Exocet.(It would hardly come as a surprise tolearn that the MoD wants to improveships' ability to detech such threats.)

In America, General Electric hasconducted studies on surface wave HFradar, and there have been reports thatthe US Navy is (or has been) doing similarresearch.

The Ministry of Defence has not yetcommented on the likelihood of interfer-ence from the British system to existingusers of the HF spectrum, includingamateurs.

AMSAT LAUNCH

The Phase IIIB amateur satellite is (atthe time of writing) due to be launched onJune 4th or 5th. It will be put into a highlyelliptical orbit by the European SpaceAgency's Ariane 7, from its launch site onDevil's Island, French Guiana.

Different parts of the satellite arebeing built in the USA, West Germanyand the UK, at a cost of £270,000. It willbe assembled in the AMSAT SpaceLaboratories in Washington.

If the satellite works satisfactorily itwill be renamed Oscar 10. It will have anorbital period of 24 hours with its apogee(maximum height) above Greenland. Asorbital speed varies in proportion to theinverse cube of height, the satellite willstay near its apogee point for aconsiderable time - long enough to keepit in range of the UK for about 12 hours aday. With an aerial pointing North NorthEast from the UK, it should be possible touse the satellite throughout the eveningwithout moving the beam.

This 24 -hour elliptical orbit is not anew technique - it is, for example, usedsuccessfully by the Soviet Union for theirMolniya communications satellites,

IMMOOW MeeeelleeeweeMeolle WWWWWWWWWWWWWWWW000000OWO OOOOOOOO MOMweee emeasiesessesw ee WWWWWWWWWWWW masseuses

vesmarevermassessaesemaasswessamessereuesswew,sesamew OOOOOOO as00seseassoliOrmallaWramOUWa1WWWWWWWow OOOOOOO swORNOMONWILWIWOOoNewesiWoesmose oSOSOMMOMOOMOSSOOManoMmeoOwledilleiliWIDealISIWOOMMOWWW0

4$

The AMSAT Phase-IIIB satellite will look like this (Phase-IIIA) whenassembled


which distribute television programmesto transmitter sites.

The satellite will carry transpondersfor 70cm to 2m and for 70cm to 23cm.Each transponder will have three 'specialservice channels' at the high and low endof each passband. These channels will becalled HI, H2, H3, LI, L2 and L3. Theexact allocation of these channels has notbeen decided yet, but it looks as thoughL3 and H3 will be reserved for AMSATengineering work. Also, a Sunday newsbulletin with a European flavour will bebroadcast on LI and H1. This will beprepared jointly by the RSGB andAMSAT-UK. The Home Office hasapproved this scheme, and othercountries may follow.

All the aerials in the spacecraft haveleft-hand circular polarisation, enablingground stations to use plane -polarisedaerials without fading. AMSAT-UKstresses the need to keep power levels onthe 70cm uplink to no more than 500W(27dBW) effective isotropic radiatedpower (EIRP). EIRP is related totransmitter power and aerial gain by:

EIRP (dBW)=TX 0/P power (dBW)+aerial gain (dBi) - feeder loss (dB)

Or

EIRP (dBW)=TX 0/P power (dBW)+aerial gain (dBd)+2.15dB - feeder loss(dB)

(dBi is aerial gain over an isotropic radia-tor, dBd is gain over a half -wave dipole.)

TELECOMMUNICATIONSBILL

The Government's Telecommunica-tions Bill, which 'privatises' BritishTelecom and tightens up the WirelessTelegraphy Acts, has had its thirdreading in the House of Commons. It gotthrough by 286 votes to 241, aGovernment majority of 45.

The implications of the Bill areexplained in the Radio Today pages ofour March issue.

NEWCOMMUNICATIONSEXHIBITION OPENED

A major new exhibition has beenopened at the London Science Museum,showing the growth of telecommunica-tions from the early days of the telegraphto the present.

The exhibition is in two adjoininggalleries - the first shows the history ofboth radio and 'landline' techniques,while the second shows some of themethods used in the present dayinternational network.

The first section includes life-sizemock-ups of the 1850 Tonbridge Railwaytelegraph office, a ship's radio cabin of

British Telecom engineers at work on a demonstration of PacketSwitchstream at the Science Museum's new communications gallery

1910 and the radio operator's position ina Lancaster bomber. Technology isbarely touched - the exhibition is aimedat the general public rather than peoplewith technical know-how.

The second gallery deals withmodern systems, and includes a mock-upof the inside of a British Telecom manhole(complete with a mock-up of a BritishTelecom employee). Other displays aimto show things like packet switching,pulse code modulation and System X.There is also a cinema showing a shortfilm, Echoes, made by STC, whosponsored the exhibition.

Amateur radio is not forgotten. Two'black boxes' share a small display casewith a CB set.

NOVICE LICENCECAMPAIGN

The Amateur Radio Novice LicenceCampaign (ARNLC) has been set up tocampaign for (believe it or not) a noviceamateur radio licence.

The Campaign accuses both theHome Office and the RSGB of 'draggingtheir feet'. The Campaign's secretary, IanAbel G3ZHI, says "since 1947 the RSGBhas failed in its negotiations with theHome Office to bring about theintroduction of a Novice Class of licence.This is despite a promise in Parliament bythe then Postmaster General in 1968, EShort, of his intentions to introduce such alicence "later in the year". The Novicelicence is already available in a number

of countries around the world."The Home Office has stated that

they have no objection in principle to theintroduction of a Novice Licence.However they are not convinced thatthere would be sufficient interest in such alicence. This is why the ARNLC has beenformed."

If you're interested write to: Ian AbelG3ZHI, 52 Hollytree Avenue, Maltby,Rotherham, South Yorks. Tel: 0709814911.

EXHIBITION SUCCESS

The RSGB's National Amateur RadioConvention, held at the NationalExhibition Centre near Birmingham,attracted over 10,000 visitors during thetwo days it was open. There were slightlymore people there on Saturday thanSunday. The move to the NEC was experi-mental, and the RSGB says that sometraders were so pleased they havealready booked space at next year'sevent, which will now also be at the NEC.The RSGB says "We hope, next time, tomake it even better."

... and NARSA

Another two-day event was theNorthern Amateur Radio Societies'Association exhibition at Southport(originally held at Belle Vue nearManchester). This event also attractedlarge crowds, but some traders say theywere disappointed by low sales.


G4J DTHARVEY EAST LONDON HAM STORE

LEXTON LIMITED 191 RANCIS OAD LEYTON E.10TEL 0F1 558 0854

R

TELEX 8953609 LEXTON G

DRESSLER AMPLIFIERS

Ttlee are high pater 240V 'mars using 4C x 150 or IC x 350 FracTunes NOT usng the vandal Gne systemFully votecte0 no Renal damage to PA teals poSSIble

DRESSLER AMPLIFIERS NOW MORE POWER

D70 70an 30C 13COn PEP £700.003118 125Mm 2006 PEP £285.00

131130 2E103004ft 600" PEP £595.00MOOS 2rtir 400A4rn 1KW PEP £695.00

GASFET DRESSLER PRE -AMPS

W2NAS 150* £40.00VV2000AAS 750* £69.00VV2000OAA5 1Kw £79.00VV2RPS 50259 Non switching 022.00W2RPS N Tyre £24.00W7RPS 50259 022.00W7RPS N Two £24.00VV Interlace £18.00PerAerect by the Wear v 60th se0x2,0 ntwa r,0 7-0 901e Srgral b POISe

0 20e ,frSertion loss GASFET MASTHEAD PREAMPS

3SK9:':0V:TE1 AyalLeye . £5.00

AVAILABLE SOON NEW MODELSYAESU FT 726 6-2-70 TRANSCEIVER + BAND WORKING FACILITY PRICE T B A + TRIO/KENWOOD.

TR7930/795025/50W FH MOBILES TR3500 70VMS PORTABLE R2000 RECEIVOR. TS430 HF TX/RX GEN COVER.

I ICOM ECM ECM TRIO/KENWOODIC740 HE 100WIC720 RHF 100W GrC1C730 Ff 1000/1C210. Erma,

1C2KLPSPSU

£660.00£883.00C586.00£829.000211.00

1C2E 2nar Irn portable

C4E 70cm to portableC15G ant 15w Nit

230 aret 10* Mist,02512r9116lmcwrsswbase

£159.00£199.00£235.00066.00£495.00

AoccssonesICLC 123 casetONM9 SP Mt;103F2 6V pad,ICBP3 W pad(

C 4.25f 12.00f 29.50C 20.00

I5930 General Coerce RX15830 ICON ieTS530 100W lf15130 101:6941S130 25W Prrs FM SS9

29/E hior Elite OA

£995 000650.000475 00E495 000090 00£245 00PS15 P S U f 99.00 C451 70crn 10* InIceds.stutese £630.00 ICBP4 empty pad( f 6.95 15796045W 0761 FM POA 0300 00

PS10 PSUAT500 A T U

10(70 RamerRSISPSU

£130.000299.00£469.00f 99.00

0490 7030 InVssb modeCSP3 SperaerCSM5 Mc

£445.00C 29.00f 29.00

IC8P5 1211 pad(

ICCP1 charting WOICDC1 12E/ ca parkLC8 Whet raseBC30 Base Choge

£ 39.50£ 3.75£ 9.75£ 18.98

45.00

182500 2rtel Porta*1R3500 Mans187730230* FMAT730

SKIMDWI GOO

0200 000.220 000145 00£11000

34 0060 00

PEO3 Fire*. INA SI3.111,

C190 000360.0011101 FRV7700A 118 150 £ 60.00

F1 ore cen comer" 1X RI.Ello2150/110miiile:mir8707 ICON 5 lam1170734150FC707 010

01295.000590.00

P 0 A.P OAP OA

FT29E19 min mods

F148013 2m1r =WeFT78014 70cm 76 omitFT780F1 70on 1 6 waft

FM 'SSA £245.00FWSS8 C365.00

Styli £400.00SUB £440.00

FFN77008 50 60 118 150FRv7700C 140 170F9V7700() 70 81118 150FRT7700 Penal Tunes

f 75.00f 65.00f 72.00f 37.00

DIAWA

55520 1 8-b0 MHZCN540 50-150 MHZ

£ 32.00£ 34.00F11071.19 bere 1054 P.OA FT2:8 ?It portable FM £195.00 FRA1700 Ache Anlema £36.00 C6161114 18150 MHZ f 52.00FP107 PSU

F1101ZD160-101,0190201A160-1Orre AM FMSP301 SparFC902 A1UR.21037 1 24W PEP Anear

P.OAt 30.00£136.95£425 CO

F1703 70Cfri pixttieFT130 2ne FM mobileFRG7700 new AM, FhASS8FRG7700 memory

,14 Mum

FM £205.00£120.001295.00C 80.00£290.00

FF5 FineMMI311FT290 Ca MountNC11C Crag,NCB Base Cnaiger(1208'208 108

C 9.95f 22.00f 8.00

f 44.00

D4630 140-150 MHZCNW518 3-30 MHZ ATUCNA1001A AUTO ATU

ROTATORS

7A875008 3 ELE BEAM MF

f 74.00£170.00

£150

£105.00FC102Ste3keFC102ATUFV102 VI 0

P 0 A.P 0.71P 0 A.

)87500X 3 ELE BEAM MF7600H HEAVY DUTY 2 Elf HOLM BEAM

307600% HEAVY DUTY 2 ELE 1401119 BEAM

95.00£148.00C138.00

DATONG

£ 56.35ASP Alto agapeD75 Manta capper

82.80£ 56.35573 Morse Tutor

Morse Readers PC1 Gen cov comelier £137.00 PFC Speach drape £ 29.90NEA *dem r105e6600Journorse P771 0610

1190.00 FL 1 Agle 5860

FL2 Actne Idlerf 79.35£09.70

AD2701rOoor Ow antAD370 Outdoor acne ant

£ 47.15£ 64.40 SONY

VOL4Ner &Baal we peers £650.00 FL3 Ave lee 8 not& £129.37 RI A Vice nand AMP 33.92 iCF2001 mane 140.00IASCO 610 Ccoanaste £169.95

Microwave modulesMML 144 30 1 3* dnw £ 9.95MEI MORSE KEYS POWER SUPPLIES

SP200 1 8 160MMZ 20 200 1KW £59.00 MML144100LSt3wdue C159.95SP300 1 8 500MMZ 20 200 1KW £ 79.00 Morse treys &ketch brass key C 49.00 Al.nco EP 2500 25 amp I c MML 144 100 S 10E/ dive C139.95SP400 1 30 500O4MI 5 10 150 C 59.00 Holculd HK706 £ 11.00 regulated with sic MMC 435 600 AfV convener 27.90SP250 1 6 60OAMZ 20 200 1K f 4100 Hirn0u01111(706 £ 20.00 protection £89.00 mm2031 RTTY recener £189.00SP15 I 08 160MMI 520200 £29.95 Hound H1(7012 £ T2.50 MM4030 RTTY trancenet £269.00OTIS° 150 40CFAIDErrrry Load £ 31.00 Kw° soLove key 100 Also EP 3000 15 amp metred MM1000 KB lei hoard - trancenet £299.00AC38 3 5 30MMZ A TU £ 59.00 electranX key £ 57.00 version voltage adjustable MM128 144 £109.95SP1OX 108 150MMZ 20 20n f 19.95 Dana DK210 Electron( lee f 41.00 6-15 volts £89.00 MM0050 Irepuency coulter 75.00C7300 Ourgly Load ALL MODELS STOCKELi

TETHB33T £189.00HB34T £102.00H835T P.OA

111335C £280.00 --N5022144 f 55.00S0220X144X4 1 90.00S0007 70cm P.O.A.

TONO TONNA

2M 5071 Linear amp 1-3Wm £ 62.00264 7CTN Imo amp 101Ain £ 90.002M 10014 Linea afro 1010An £115.008 500 CW RTTY Terminal £299.00

44 AELE £12.00432/440 21 Eli (19.001 44 9ELE 432/435 11 ELE AN f27 00144 9ELE =sea 30 0 144 435 9 19ELE £31.00144 9ELE portade 300 144 1SELEX £30.00 JAYBEAM

SCANNING RECEIVER 144 16ELE f33.00 1296 23FLE £17.00144 13ELE portable £29.00 Pissing Roes

TB3 HE 3 lot`,,R3 tared vender

£189.00f 46.00

8XY2M £35.0010002M £45.00

Scano.ng Recever SE200N C249.00 430440 I9FLE crowd lelescopc masts 052M mono f 54.00 04 244 £29.00Drawn SR IMO f 70.00 435 19ELE £19 00 5Y2M 5ELEYAGI £ 14.00 06/2M £39.00

872M 8ELEYAGI E 17.00 082M £44.00ROTATORS144MHZ 431MHZ 1250-129E,

10Y2M 10 10786)I £ 24.00 MBM5413/70cm C35.00Wpm KR 250 C 44.95 4ELE £12.00 19ELE £18.00 23ELE £25.00 PBM1010EPARABE AM C 44.00 MBM813/70cm £48.00Harshmann HR /50 f 50.00 9ELE Fix £15.00 19ELD1 126.00 reiescobc Masts PBM1414EPARABE AM f 55.00 8XY 70cm £42.00Knot° KRADZIIC £100.00 9ELE Pan £17.00 21ELE AN £28.00 4,1M £15.00

5092M f 28.17 1207 70cm £52.00Kiwi° merlon Four" f 85.00 9ELE E MOO 144'435 9+ 19ELE MOO 4x244 £28.00

13ELE Pal £26.00 3E2M D9.00 HOXINDx1 Osage TX TX 04.00:.'n Or urn NuirtiinC5800 kI ' -i ,v 25W SSB FM CW 2rro

GP5 ant, carearPow spellers et avanabie 411500 BO 40 20 15 10 mIr

k..._ £359.00 6408 £33.00 vertv.al £84.00 .../

ALL ACCESSORIES AVAILABLE PLUGS SKTS CO AX 2IVITR COLINEAR £31 50 70CIVI COLINEAR £31 50

PRICES INCLUDE VAT AT THE PRESENT RATE OF 15%OPEN MON FRIDAY 9 00 5 30 SATURDAY 10 00 3 00 INSTANT HP FACILITY AVAILABLE

EASY ACCESS M2 M11 M1 NORTH CIRCULAR ROAD EASY PARKING VISA


The Factsand Fiction of

AerialsAmateur radio has distinct similarities with the pursuit of a better hi-fi

system. Give or take a fraction of dB, all audio amplifiers are thesame. The way to better audio lies in the choice of loudspeaker system

and signal source. When it comes to RF, there is little to choosebetween the various Japanese black boxes except the price. The most

important thing that you can have is a decent aerial system.

When buying an amateur radio sta-tion off the shelf, as much as half thetotal purchase price should gotowards provision of the aerialsystem: a 10 watt two metremultimode costs, say, £350. A basicaerial system will add another £50.You want to put out a better signal soyou invest a further £300+ on one ofthose magnificent Dressler linearamplifiers. The power goes up to200W, the price goes up to £700+and received reports should showanother 21/2 S points on everybodyelses' S meters. Your meter,however, will still be giving thesame reports as it always did.

Going back to square one youbuy your lOW transceiver, spend£150 on a rotator (cheap ones arefalse economy) vertically stack four8 -element Yagis (£100) and dividethe remainder of the investmentbetween the purchase of Westlake'sH100 feeder (much lower loss thanUR67) and some strong aeriallashings. The result of this approachwould be to collect an extra two tothree S points on received reports

By Frank Ogden G4JST, EditorHAM RADIO TODAY

while having improvements of thesame order on your reception .. allwith a basic 10W set. If you then addone of Lexton's amplifiers, you willhave a potent station indeed.

Aerials and feeder systems areimportant because there is no otheraspect of a station which acts toimprove both send and receivesimultaneously (except perhapsmoving house to a better locationbut that is expensive). Even the bestin GaAsFET receive preamps willgenerally do less for your receivenoise figure than just a very modestYagi.

A general point

The performance of any aerialsystem is determined almost entirelyby the amount of metal interceptingthe incoming radio wave. The wayin which a radio signal is convertedto an RF voltage at the aerial socketis dependent on laws of physics, notadvertising claims.

The corollary to this is that anaerial system having the same

number and arrangement ofelements will perform as well as asimilar aerial system from any othermanufacturer. When you choosebetween aerial manufacturers for aspecific aerial type, for instance 2m10 -element X/Y, you must look fordurability, wind loading and price,not the specified aerial gain. Therewill be minor differences such asslight variations in bandwidth frommanufacturer to manufactureralthough the perceived differenceswill be minimal or non-existent.More on the topic later.

Going mobile

All the points made in the lastcouple of paragraphs apply evenmore thoroughly to simple aerialsystems than complex ones. A 5/8boot mount is a 5/8 boot mountregardless of who makes it, a 2 x 5/8base station co -linear has electri-cally the same characteristics as asimilar arrangement of co-linearsfrom any other manufacturer youcare to name. Likewise with quarter -


waves, halos and rubber ducks.The only differences between

types is in manufactured quality. Acase in point, the ever popular 2mmobile 5/8 wavelength whip. I'vehad a number of these things on mycar over the years and confirm thatthey all work equally well whennew. However, the cheap typeswhich use the integral loading coilsuffer badly from internal corrosionof the loading coil guts after acouple of years' service. The rainand Winter salt spray gets in and thecopper plated steel coil literally rotsaway. Against this, the expensivetypes with demountable aerial whipsand coils sealed against theelements have always been nickedfrom the car before I've ever had a

chance to see whether theydeteriorate any slower.

There are pronounced dif-ferences between the aerial types.1/4 wave aerial whips mounted cen-trally on the car roof perform betteraround town - where there arestrong multiple reflections - thangain systems: 5/8, 7/8, etc. Shortaerial whips produce less mobileflutter than the longer ones althoughin open countryside, the strongersignals of the big aerials offer a con-siderable advantage. In my opinion,the 5/8 system offers the best com-promise between mobile flutter andsignal strength.

Juggling figuresManufactured quality, rather

than specified performance, is thething to look for in base station co-linears. In any case, the specifi-cations themselves are verymisleading. Virtually all beam typeaerial systems are referred to asimple dipole when it comes tocalculating dB of gain. For somereason, the reference used to judgethe performance of omni-verticals isthe quarterwave groundplane. Thisgives most vertical aerials types 3dBmore gain than they actually havewhen compared to a dipole. Putanother way, a simple dipole ex-hibits 3dB of gain when comparedwith a quarterwave groundplanesystem.

Putting the record straightabout mobile aerials, in comparisonto a dipole (OdB) the 5/8 has OdBgain, a halfwave exhibits OdB asdoes a Slim Jim while the 7/8 showsall of 1.5dB real gain. The classicdouble 5/8 co -linear weighs in ataround 2.5dB over a dipole. By con-trast, the most basic 2 -element beamreturns roughly 3.5dB of gain over adipole.

Hand portableHanditalkies used as such are

remarkably inefficient radiators.The body has to provide the groundimage, the other side of the dipole.Since some rubber duck type aerialsonly have a radiation resistance ofbetween five to ten ohms andacknowledging that the body is alossy, high impedance radiator,very little RF actually gets out, or isreceived.

The answer is to use a half wave

ELECTR GAILY

TURNS1/4 DIAMETER

TAPPED 1Y, TURNS18 mg

BASE LOADINGSTEP UP COIL

1

10 TURNSIii"A DIAMETERCOILL18 mg

Fig. 1.Improvedhanditalkie aerialfor two metres

fria.ONG PLUG

2-


20

18

16

14

12

10

8

6

4

2

QUAD TYPE AERIAL zYAGI TYPE A E IAL

Fig. 2. 0 2

Comparislon of aerial gain as afunction of typo and number ofelements (source GUST)

3 4 5 6 7 8 9 10

NUMBER OF ELEMENTS

20 30

aerial, a system which provides itsown ground image. Fig. 1 describessuch a system. The bottom tappedloading coil steps up the resistancefrom the 50 ohms characteristic ofthe handitalkie to the several thou-sand ohms of the centre loadedhalf wave dipole. Since the circu-lating currents into the handitalkiecasing - and hence into the body- have been reduced by an order ofmagnitude, the arereduced to minimal proportions.The perceived portable perfor-mance boost is dramatic. You canpurchase ready made half waveaerials for 70cm, but you willprobably have to make your own for2m use.

Beam Aerials

There are usually only twocriteria for people who are putting

Fig. 3.Typicalradiationpattern for six -element Yagi. Thispattern would be typical for both thevertical and horizontal (beam elevation andbeam heading) directions

"S.

up a beam aerial system for the firsttime: how much gain for how littlemoney. It is a perfectly respectableattitude but there are other factors totake into account. For instance,what kind of gain do I want? Will myrotator take the weight and thewindloading? Will the thing fall tobits in the first Autumn gale?

Kind of gain

It goes without saying thateveryone wants the most gain thatmoney can buy and I am not goingto go against that view. Fig. 2 showsa plot of aerial gain against thenumber of elements for both simpleYagi and quad aerials. When itcomes to assessing performance, theprecise method of manufacture isrelatively unimportant. It is thenumber of elements that counts.However there are other ways of

VIEW

Fig. 4.Typicalradiation patternfor two vericallystacked three -element Yagi would show an identical patternexcept that all lobes would be 3dB less in amplitude

GAIN OfOD FEAT NC!cIFOLf

111.4DOW1.I GAOf STACKED41111/kv- C

achieving gain which have distinctperformance advantages.

Stacking of aerial arrays leadsto increased gain at the rate of 3dBfor each doubling of the number ofaerial arrays. Dependent on howthey are stacked (either side by sideor on top of each other) the resultingradiation polar diagram can showdistinct advantages over a single bigYagi or quad of the same nominalgain.

Fig. 3 shows the polar plot of atypical 6 -element Yagi. The maxi-mum forward gain will be around9dB but the beam width - typically.in the region of 40° - will besubstantially the same in both thehorizontal and vertical planes. Withthis pencil type of beam, you have topoint the aerial fairly accurately torealise the system gain. This is fineproviding that you know exactlywhere to look for a station. However,

r=RFO.C WEI

al... lf.4Mir" -.14

GAM OffIWIEN.

SIDE WOLFV EW

Fig. 5.Typicalverticalradiation pattern

dual three -element Yagi arrayof vertically stacked


if you are monitoring the calling fre-quency, you might not hear weakstations that are not exactly on yourbeam heading and thus miss a lot ofthe action.

A typical three element Yagihas a gain of 6:1B. If you connect twotogether - with a suitable matchingharness of course - the forwardgain rises to 9dB, the same as for thesingle 6 -element case. It might seempointless to go to the trouble ofphasing and mounting two aerialswhere the same gain can beachieved with one but there are realadvantages.

Fig. 4 shows the polar plot oftwo vertically stacked 3 -elementYagis. There are two points to note.Firstly, the horizontal plane radia-tion pattern indicates a beam widthof at least double that of a single6 -element Yagi even though therealisable gain is the same. In prac-tical terms, the array is not nearly socritical of beam heading. The otherpoint is that the horizontal lobecharacteristic does not differmarkedly from a single 3 -elementarray. The same is true of four ormore tier systems. Fig. 5 shows thatthe beam narrowing occurs in the

vertical direction only. This isrelatively unimportant since thearray elevation will nearly always beparallel with the horizon. In otherwords the vertical stacking changesthe beam from the pencil form of thesingle Yagi to a fan shape.

Yagi v quad

It is possible to treat these twopopular types of aerial in much thesame way. The only real differenceis the extra 1.5dB of gain that a quadsystem will have over a Yagi array ofthe same number of elements.Against this, the quad aerial, ele-ment for element, has almost twicethe metal of a Yagi. This increasesthe wind loading and weight.However, there are compensations.Long quads are supposed to beeasier to match than long Yagis. Themain point about quads though isthat they give more gain for a givenboom length.

There is one proviso to all thesequests for gain. It is important to getoptimum matching and phasing. Itis very easy to lose hard won perfor-mance. Home built aerial designsare prone to this but little trouble

should be encountered with goodquality professional units. Providedthat the input SWR to the aerial isbelow 1.5:1 no significant perfor-mance shortfall will occur. Evensystem SWR's of 2:1 will not degradeperformance particularly.Remember too that long feeders arelossy. UR67 or better should be usedfor all runs over about 20ft on 2m.70cm requires UR67 for all runsover 8ft. I would personally recom-mend the new H-100 coax from W HWestlake. It has a much lower lossthan UR67 yet costs just 90p/metre.

"Me and your mother are getting a bitworried about you son. Shut in here,night after night - get out and talk topeople!"

SLIMLINE MASTS or LATTICE TOWERSFIXED TOWERS or MOBILE TRAILERS

THE WAY AHEAD

PORTABLE MASTS or WINDOW MOUNTINGYOU NAME IT! WE PROBABLY MAKE IT!

SOME TYPICAL DESIGN FEATURES VERSATILE MOUNTING, POST, WALL OR TRAILER UNIQUE 15FT SECTIONS FOR MINIMUM LOWERED

HEIGHT AND EASY TRANSPORT PURPOSE DESIGNED AND ENGINEERED TO B.S.I.

STANDARDS. WIND LOADS TO CP3 CHAP. PT. 2 ROBUSTLY CONSTRUCTED IN QUALITY STEEL ITO BS

1775 BS 980. BS 43601 OPTIONAL HEAD UNITS (Extra).

WELDED BY ELECTRONICALLY CONTROLLED M.I.G.FOREXTRA STRENGTH TO BS 4872,

MORE THAN 50 TYPES OF MAST OR TOWER FROM 3011TO OVER 100FT.

TELESCOPIC TILTOVER FOR EASY ACCESS. SAFETY LATCH TO RELIEVE CABLE SIMPLE WINCH OPERATION iSingle and Double,. HOT DIP GALVANIZED FOR PROTECTION IBS 729).

A FEW POPULAR MODELS FROM OUR WIDE RANGESLIMLINE MAST SM30. Unobtrusive. Telescopic. Tihover,up to 31h. SM3OWM tWall Mount) £230.00. SM3OPM (PostMounting) £241,00. Optional Reducer Tube RT1 E12.50 RotorHead RH1 E30.50. Ground Socket GS1 £23.50..

LATTICE TOWERS - TELESCOPIC - TILTOVERSeries 1 32AT AT32PM for £363.00. AT32WM £348.00Series 2 Heavy duty 44ft AT42PM £481,50. AT42WM£445.00. 5611 AT52PM E599.50 AT52WM £579.00.Prices include all winches, luffing gear, brackets, head unitetc. As applicable. Mainland carriage (door to door). AndVAT @ 15%. Terms C.W.O. Send for details. Prices may alter.Please allow 28 days for delivery

We design - we make - we supply direct. At manufacturers prices. You get best value andservice. No middle men. We offer no gimmicks. No free gifts. Just competitively priced

quality and reliability. We have been doing it for over 12 years.Callers welcome. /Samples on display. Opening hours: Mon-FrI 9 am -5 pm.

Sat. 9 am -12.45 pm.

ALL ALTRON PRODUCTS ARE EXCLUSIVELY MANUFACTURED IN THE U.K. BY

ALLWELD ENGINEERINGUNIT 6, 232 SELSDON ROAD, SOUTH CROYDON, SURREY CR2 6PL

Telephone:01-680 2995 (24 hr) 01-681 6734

HAW- , rk,nut.


Eleven to TenTo the comparative old timers; thatis the early G8 s and laterG3 s the present multitude ofblack, grey and blue boxes mustoften cause nostalgic reflectionsback to the good old days of theiramateur beginnings. In the late &CSand early 70s the normal way of get-ting on the air was either by rollingyour own or modifying governmentsurplus gear or ex -commercialequipment. The early days of two -metre expansion (when 144MHz wasopened to the Class B brigade)meant that the majority of rigs wereex-PMR, Pye, Storno, Cossor etc.Nowadays an all singing and danc-ing rig capable of working at leastsix repeaters via a linear and multi -element beam seems an essential re-quirement of the newly licensedG6 , and the state of two -metre operating confirms this fact.Many operators must have longingsfor the good old days and those whohave moved on to Class A have suchan escape open to them, namelymobile FM on 29MHz.

With the advent of CB, equip-ment capable of easy modification to29MHz is available cheaply. Someof the transceivers around are of areasonably high standard, givingscope for modification to good per-formance at very low cost. Cheapmobile aerials are also readilyavailable.

40 channelsA typical block diagram of a 40

channel (10kHz spacing) CB setwould be as in Fig. 1. For simplicityan AM set is chosen. Details on con-verting an AM set to FM (with a per-formance typical of 145MHz gear)will be given later.

The basic transmitter andreceiver circuits are fairly conven-tional in that a low power PA isdriven by a simple driver, bothstages being modulated. The pre -driver stage is excited by a frequen-cy synthesiser which also includes asafety circuit. This cuts the transmit-ter off if the synthesiser goes out oflock. The synthesiser consists of avoltage controlled oscillatoroperating (in this case) at the output

Converting 27MHz CBsets to the 10 metre

amateur band

by Bill Sparks G8FRX

frequency minus the first IF(generally 10.695MHz). The syn-thesiser is locked to a multiple of10kHz, derived from 10.240MHzcrystal. This 10.240MHz oscillatorcircuit also drives the secondreceiver mixer, giving a second IFof 455kHz. The VCO frequency ismixed with the 10.695MHz oscillatorto transmit on the same spot as theRX input frequency. Suitable T/Rswitching is provided and the rigoperates like just about any othertransceiver. The main differencebetween the conventional amateurarrangement and the one discussedabove is that the injection frequencyto the first RX mixer is lower than thereceived channel, whereas it is nor-mal amateur practice to operatereceiver oscillators on the high sideof the signal frequency. The varietyof CB equipment is extremely widebut certain basic similarities are

found. The major variations are inthe frequency synthesisers. Sinceour aim is to transfer the operatingfrequency to a point some 2MHzhigher we will consider the syn-thesiser stages first.

Basically, there are three maintechniques used in synthesiser cir-cuitry in CB sets although certainother oddball circuits exist. Thethree methods are as follows:

a) To prevent any form of conver-sion to additional frequencies a formof Read Only Memory is incor-porated in the PLL whch isdedicated to giving only the fortychannels recognised by the FCC inAmerica. Typical devices are the(see Appendix 1) 7137, 7130 and7131. These devices are invariablyoperated by programmed inputlines usually by a 6 bit code.b) Another form of pre-programmeddevice uses a so called 'random'code which is a variation of the 7 bitBCD code, eg. 9106 & 9109.c) The major proportion of the setsused phase locked loop circuits con-trolled by a straight binary inputand these are comparatively simpleto re -tune. A brief explanation ofbinary arithmetic is given in Appen-dix 4.

Dedicated v binaryIn type (a) & (b) the device is

Receiver

1st mixer 2nd mixer 455 kHz DemodulatorR F amp 27-10.695 10 695MHz main I.F squelch

MHz - 455kHz stages andAGC

16 27-16 71MHz 10 240MHz

Frequency synthesiser zMH MIc oAudiand

reow-1Audio output

midriverc and AML +VC Oetcl pre amp modulator

27MHzL5

1627-1671MHz

Low pass R F power RF RE Transmitfilter .11.01114.11.

amplifier111..

driver predriver MOW

Fig. 1. Basic TCVR

Transm tter 10 695MHz


usually loaded with forty discreteoperations and these are called upby the input logic variation, but intype (c) the number of operationscarried out by the device is controll-ed only by the binary number rangethe device will accept. In manycases as many as nine inputs or pro-gram lines are available, thus giv-ing 2' variations, ie. 511 differentlines. Since we originally stated thatthe channelling was at 10kHz inter-vals this gives a tuning range of5.11MHz.

The simple operation of a syn-

covering 29+MHz it is necessary toalter VCO to give 29.5-11.695MHzas the operating range.

In the example quoted the chan-nel switch on channel 1 gives anoutput code of 136, so our new fre-quency on 29MHz at the lowest endof the range should be controlled bya 136 programmed input to the PLLto be used. By substituting a 17.245crystal for the 14.910 crystal in theoriginal circuit our transmit fre-quency should now be between29.300 and 29.700. However, due toFCC regulations, the original FCC

frPhase detector

pLow pass utter

o

Voltagecontrolledoscillator

to

Fig. 2. Simplified phase lock loop.

[0]

thesiser PLL circuit is shown in Fig.2. When the reference frequency f,and the VCO frequency f are ap-plied to the phase detector, thephase difference is measured in thephase detector and converted into aDC output which is applied to theVCO via the low pass filter. Sincethe comparison is made every cyclethere will be harmonics and noise atthe output P, hence the need for thelow pass filter. The integrated DCvoltage applied to the VCO causes afrequency change to occur, theVCO output being returned to thephase detector. The closed loop willcontinue to operate until there is nophase difference between thevoltage generated in the VCO andthat of the reference. The VCO isthen locked on to the reference fre-quency and the VCO output (f.) isin phase lock with the reference.

To apply this technique in realterms some additional sophisticationis required. Since variable frequen-cy dividers used in these circuitshave a fairly low frequency max-imum count limit and we require a10kHz channel spacing we have toaccept that we are referring to a10kHz reference and that our VCOfrequency of approximately 17MHzhas to be divided by some 1700. Toovercome this problem the VCO fre-quency is mixed with an offsetoscillator, to give a lower variablefrequency which does not requiresuch a high division ratio. Figure 3indicates a fully operational ar-rangement.

In order to achieve a range

frequency allocation to CB had cer-tain discrete gaps at 50kHz inter-vals. The channel switches weredesigned to skip these numbers intheir output; so a typical outputsequence from the switch used inour example would be 136, 137,138, 140, 141, 142, 143, 145, 146,147, 148, 150 and so on up to chan-nel 20, where normal sequentialcounting took over up to channel22. Channel 23 required a count of165, whereas channel 22 was 162.The sequence at this point was chan-nels 22 - 24 -23 - 26; then nor-mal counting up to level 44 or in ourinstance 180.

By interrupting the programlines from the switch and feedingthem via a suitably programmed

EPROM the necessary correctionscan be made to the coding, so thatthe switch reading 1-40 gives a pro-gressive binary input to the PLL,enabling a true 10kHz channel se-quence.

In some instances the VCO coilmay not tune to the new frequen-cies. This can be changed fairlyeasily either by reducing the lengthof the coil or by reducing the coilpadding capacitor.

Where it is necessary to replacethe synthesiser due to it being adedicated device, the simplestmethod is to introduce a compositeboard containing the EPROM andthe alternative synthesiser. Asuitable board is shown in Fig. 4together with the circuit and layoutin Figs. 5 & 6. As the circuit in-dicates the program lines are fed tothe EPROM and the modified pro-gram is then fed to the synthesiser.The details of operation and installa-tion will be dealt with later in the ar-ticle.

PCB drawings Figs. 4, 6 and 9 willappear in a future issue.Unfortunately there were mistakesin the original artwork - Ed.

Another technique was often us-ed to cut the number of crystals. Bytaking the 10.240MHz signal anddividing it by two, a 5. 12MHz signalwas derived. This frequency wasmultiplied by three to give15.36MHz which was then mixedwith the VCO. This was then submit-ted to the divide -by -N module, giv-

Mixer

tL

14 910MHzoffset

oscillatortL

Programmabledivider-N

VCO-tLN

16-17MHz

Iv VCO

Low passfiller

Unsmoothedcorrectionvoltage

Phasedetector

10kHz

To mixer1T

Tx offsetoscil ator10 695MHz

f IL

Command switchgiving channel

selection inbinary number N

Fig. 3. Typical synthesiser arrangement

Referenceoscillator

and divider10 240MHz

Rx 1stmixer

Outputappro.27MHz

10 240 outto Rx and 2nd mixer


ing a count range similar to the onesdiscussed previously.

From the discussions so far itwould appear that the majority ofsets around could be converted tooperate on 29MHz FM.The use of the 10.240MHz crystal asthe reference oscillator permits avariety of functions.a) The division by 2° gives 10kHzsince 210 is 1024.b) Division by two and multiplica-tion by three gives 15.36MHz whichis a handy offset frequency, alsomultiplication by two gives20.480MHz, also a handy offset fre-quency.c) The technique adopted in nearlyall the units is to operate the VCO ateither (input frequency +10.695MHz) or (input frequencyminus 10.695MHz), 10.695MHz be-ing the value chosen for the first IF.By mixing this 10.695MHz with10.240 in the second oscillator thestandard 455kHz IF is produced.

Referring back to our originalcomment on (b) above, the devicechosen for the alternative syn-thesiser was a Motorola deviceMC145106. This operation of thisdevice is shown diagramatically inFig.8. The particular device usedhas an effective counting range of109 (2 ° - 2 8) or some 512+ inbinary steps. The technique finallyadopted is to count in units of two,ie. 2, 4, 6, etc. and to utilise the5kHz split so that each step is 10kHz(ie. 2 x 5kHz). However by swit-ching internally the device cancount in even pairs, ie. 2, 4, 6, 8etc., or in odd pairs, 1, 3, 5, 7 etc.This technique allows for the

with the 10.240 frequency toachieve the required output in theT/R switching.ie. VCO + 455kHz + 10.240MHz =TX frequency

In practical terms the VCO out-put is fed to a simple transistor mixerwhich is hard switched by the15.36MHz derived as shown in thecircuit diagram for the board, Fig.4.

The two devices shown at the in-put to the dividers are Schmitt trig-gers, which assist in preventing ran-dom noise from operating thecounters, by squaring the shape ofthe input pulses. In the case of con-version to MPT1320 the 5kHz techni-que permits a frequency shift of astraight 64 in count (27.605 -26.965) and then 5kHz correction ofthe 27.605 to bring it to 27.600. A

Fixedfrequencydivider

Referencefrequency

Phasediet

Low passfilter 1-11W-1

Divide by Nprogranwnable

divider

Voltagecontrolledoscillator

Pray ammo linesf ern channel

switchFig. 7. Characteristics of straight synthesiser.

Down mixerto establishcount onge

Down mixoffset

frequency

455kHz receiver IF. This is nowderived by programming the deviceto read 91 steps which at 5kHz inter-vals is 455kHz and then mixing this

slight tweak to the 10.240 crystalthen brings the resultant frequencyto within 1-200 cycles of 27.60125.Similar techniques will permit the

10240

11I1024

Down mix

15 3 6

x3

5.12

Tx mix

Fixed refdivider

N counter

VCO

Loop niter

T/ R

A it A

Switch

Fig. 8. Technique used in circuit adopted (MC145106)

x

x


circuit to operate at any requiredfrequency within the capabilities ofthe counter and the VCO. Toremove the gaps on the FCC sets,suitably programmed EPROMscould be used as follows. In the caseof the sets using the straight binaryinput PLL where the original syn-thesiser can remain in situ, thetechnique adopted is to cut thetracks from the switch to the device,and feed the program lines from theswitch to the input lines of theEPROM via the address lines,remembering to keep the lines in thecorrect order. See Fig. 9.

In the EPROM used on theboard shown in Fig.4 the least

significant digit is fed to addressline 8 and the most significant to ad-dress line 3 in the case of 6 bit BCD.Address line 2 is used as the T/R line

to introduce the offset of 455kHz inthe specific program on this EPROMbut in the case of straight binary,address lines 8 - 1 are used as in-puts. A suitable board layout for thecode transfer is shown (Fig.9). Thisprovides a facility for introducing a5V regulated supply. It will be foundin many cases that the leakage at theinput of the EPROM address lines is

so low that static charges can buildup. It is therefore advisable to installpull -down resistors (50K - 500K 1/8watt), across the wide earth line inthe centre of the board. (Shown inFig.9.

The loop filter shown in thediagram of the 145106 devices is im-portant and due to its criticalnature, when the system is being us-ed as an alternative to dedicateddevice it is important to completelyisolate the original loop filter toavoid incompatibility problems.

In order to explain the techni-que still further perhaps a look at atypical binary indication wouldhelp. In view of space restrictionsonly certain channels will be shownbut the sequence, being additiveshould be easily followed as in-dicated in Table 1. (For further in-formation on binary codes see ap-pendix 3).

In the first example a differenceoffset frequency in which the VCOwould be operating in the 36MHzregion is shown. The offset frequen-cy could be derived from a crystaloscillator operating around 37MHzor the circuit could use a 17MHzVCO with the 10.240 crystaloscillator being doubled to20.48MHz if mixed with the 17MHzVCO this would Dive a down countfor an increase in VCO frequency.Both techniques are used.

Table 1

Code 256 128 64 32 16 8 4 2 1 Powers of 2Frequency Sum 7 8 9 10 11 12 13 14 15 Pin Number

27.601 74 0 0 1 0 0 1 0 1 0 Using pins9-15 only with27.701technique

64 0 0 1 0 0 0 0 0 0 down count

27.801 54 0 0 0 1 1 0 1 1 0

256 1 0 0 0 0 0 0 0 0 Using allpins 7-15

257 1 0 0 0 0 0 0 0 0 and up count

260 1 0 0 0 0 0 0 0 0

511 1 1 1 1 1 1 1 1 1

26.965 136 0 1 0 0 0 1 0 0 0 Pins 8-15

27.605 2(X) 0 1 1 0 0 1 0 0 0

27.995 239 0 1 1 1 0 1 1 1 1

29.605 400 1 1 0 0 1 0 0 0 0 Pins 7-15


The interesting point is that the40 positions on the channel switchcan be placed at any point betweenthe count of 1 and 511, this giving afrequency coverage of over 5MHzwith a 10kHz channelling or2.5MHz + with 5kHz channelling.The important feature to recogniseis that the code lines from the switchshould not over -range the availableprogram range. In other words theuse of six program lines will onlypermit a count range between 63and 0 so if the switch gives out 136

- 174, the range must include eightinput lines. A simple device couldbe shown as in Fig.10.

By closing switch 6 we have apre -loaded count of 224 already inthe line, using switches 1 -5 givesus a count range of 31, so we havenow an effective range of 224 -255. By closing switch 7 and open-ing all the other switches we nowhave 256 count. By progressingthrough switches 1 - 5 gain with 7closed we can now count to 287 sothat in effect using the above techni-que we have a count range of 224 -287, so 64 positions are open to us inthis instance from the combinationsof switches 1 - 7, and the 64 posi-tions can be seen anywhere up to511, ie. the 640kHz swing can be atany point in a 5MHz range. As canbe seen we have pre -loaded 224 sothat it becomes obvious that by pre -

loading any quantity up to 256 wecan set our operating range to suit,but in order to cover certain areaswe may have to arrange an in-termediate switching of the loadedpoint.

The practical operations involv-ed are relatively simple and by us-ing EPROMs to carry out themechanical operation just describ-ed the techniques are well within the

skill of the average amateur. Themain problem is in the programm-ing of the EPROMs. The importantfeature is to establish the programalready being fed to the EPROM bypreparing a truth table on the pat-tern shown for the MC 145106. It isonly necessary to check the code atchannel 1 and channel 40, the restcan be calculated. The techniquefor establishing the code pattern isto check the voltage level on each ofthe program lines in turn at theselected channel switch position. Avoltage of some five volts indicates alogic 1, and any voltage less than0.5 indicated logic zero. It is ad-visable in these cases to use ananalogue meter of some 20,000ohms per volt to present a suitableload otherwise random staticvoltages may affect the readings.

In discussing the practicaloperation probably the mostsuitable manner would be to use oneof the most common circuits. Theone chosen is used by a variety ofmanufacturers and is given inFig.11. The VCO control voltage isderived from pin 17 and goes viaR201, C203 and R204 to the varicapdiode D201 which is across the coilL203. C304 serves as the DCisolating cap and has a loading ef-fect on frequency range, so being inseries with the varicap controls theVCO operating range. The KC7310device acts as the transmit mixerand VCO. The VCO output is tap-ped off at pin 2 of the 7310 and fedvia C305 to the PLL, in this case a7131. The VCO return via C305 isred to pin 19 of the PLL and in thePLL is fed to the programmabledivider. This is controlled by an in-ternal ROM and this ROM acceptsthe input lines from the channelswitch (pins 1 -6 incl. ).

The T/R line instructs the inter-nal ROM to read the offset and con-sequently moves the VCO frequen-cy, as discussed previously. A cer-tain amount of the RF is fed back tothe PLL via pin 14 as a lock checkand an out -of -lock indication causesthe device to inhibit, this preventingany off -frequency transmission.

The channel switch controls thedigital information to the device andat the same time this information isfed to the digital display.

The techniques required tooverride the synthesiser shown andto vary the output frequency to apreviously determined range are allaccomplished on one board. (Fig.4)

This board accepts the incoming in-formation and takes over control ofthe VCO in the following manner.

The program information is fedto the EPROM and this transforms itto an acceptable code for the PLLused. The control functions aretaken over as per the layout shownfor the device and the actual circuitused is shown in Fig.4.

The physical operations involv-ed are to lift the end of R201 adja-cent to TP1 and clear it from theboard. Run a wire from Pin 7 on thenew board (shown as output ondiagram) to this resistor. The 10.240crystal is removed and soldered onto the new board together with the-)61IF capacitor. The other capacitoris replaced on the new board by a33pF cap. The program lines areremoved from pins 1 -6 on the oldboard and inserted in pins 8 -3 onthe new board. A T/R line point istaken from the junction of R316 anddiode MA 150 (D209) and fed to pin2 on the new board. The 12V point isfed from the set side of the on/offswitch and a suitable earth connec-tion made. The VCO return is takenfrom pin 2 of the 7310 mixer by firstremoving C305 and taking the wirefrom the 7310 side to the new board.The inhibit line is disabled by cut-ting the track at pin 14 on the 7130.

By connecting a voltmeter bet-ween pin 8 of the new board andearth the conversion should be com-plete. Initially set the channelswitch to channel 20, then adjust theVCO coil until a voltage of some 5Vappears at pin 8. This voltageshould stay at 5 volts when the chan-nel switch is moved from 1 - 40.This indicates that the circuit is inlock throughout the new frequencyrange. In the case of difficulty thecheck points are as follows: -

a) Check on pins 2 & 3 of the 145106to ensure that the 10.240 oscilator isworking.b) Check pin 5 for 5.12MHz output.c) Check at mixer transistor for15.36MHz, if not present adjusttripler coil to give a maximum of15.36MHz output (core flush withtop of can).d) Ensure that EPROM is receiving 5volts and no more.e) Check that T/R line is switching.f) Ensure that VCO return is pre-sent.

The actual RF voltages as shownon a scope should be in excess of 0.6volts in case of the RF return from


OM

OM

00,

1142

61C

1 22

C e

n00

11.0

04 0

11.5

2014

0 2

3C22

3W

S 10

9.14

2600

TIC

023

0201

/220

0 02

02 0

3110

340.

012S

C/3

3M

OO

102

1240

121.

21S

C5O

0202

.111

0201

24 2

5040

30*

004

200C

2 23

0211

02.

0102

-002

052

EC

T20

1,22

002.

0302

2063

06, 2

0005

NO

RA

WL

TS

AT

T11

.111

11T

CO

MM

*A

LL

WO

WS

tAL

OW

PEO

MO

M C

WO

O00

2.1

20 D

C D

T W

A A

T 0

0 So

ul20

to e

t, PO

PPE

R s

orto

004

.1.0

0002

0022

012D

442

ft02

232

Oe

*Or

02.1

Dom

HA

IM 0

.000

.ro

otpr

f211

100/

100T

20C

0011

6220

r WC

172

2010

1T

OL

Ida

2./.3

02

1SC

O C

002

40C

H S

w

FOR

LE

O W

M

LiIl

LE

O A

WL

S

WW

2

DE

VIC

OW

I1C

T00

121

0242

/ CO

MIC

/ 001

C

DW

I PM

*5

102

022

061

vw C

CC

t0C

Iel

1300

296

002

23C

222

4 H

51

0141

1171

771

=E

NI

II

II

II

II

II

200

2212

1M

I02

01C

OO

N

2a20

402

20.

140

012C

O21

220

0271

0424

1e-4

200

°H,

g0* '3

7_

z),1

3vc,

c, 111.

0101

11.

110

IF M

P

DC

.. 3P

5-41

00 I

RO

--10

1101

--2

MV

Cr

200

4

I

aiI

0..v

I, I

2006

,w

720

110

IC 2

01

CR

O O

OP

MI

4,..

ir,

r1V

CO

O u

p.

......

.v.c

r.rf

AD

JUST

1221

0320

021

war

822

125

CR

I 00

0100

I

RI

2102

0 00

00R

P Po

sa, N

M

Fig.

11.

27M

Hz

AM

CB

cir

cuit

used

by

seve

ral m

anuf

actu

rers

C9

Sto

24

CH

A21

111

GO

ON

Q T

ow m

iAT

Iv2

1011

0LE

0CO

NT

RO

LN

OT

516

110

102

801

J2SP

WY

I I"M

O 0

.08

SOO

1 1-

17"1

-1J

I-.

-

20

0c.

T S

P21

0

C2.

0-C

O.1

N55

240

0424

i1---71

rh

CN

WC

0042

02

nc-'1

r77

C34

4-2

117]

.C

340-

12C

344-

01C

341

- 30

1/C

50-

20P

rt

ca. o

ou

the VCO viaC 306/C 307.

The pre -emphasis achieved issome 6dB per octave and the firstlow pass filter give a roll -off of some6dB per octave after about 2,930Hz.The other filters give an additionalroll -off of some 12dB per octave sothe audio response is as in Fig.13.

The effect of using an adjustablegain stage in the initial part of thecircuit followed by an amplitudelimiter is to give a sensibly constantaudio output over a range of inputs

the VCO and the 15.36MHz injec-tion to the mixer on the board asshown in the appendix.

Various techniques areavailable for a variety of circuits butall follow the basic arrangement asoutlined above. The stability at-tainable is well within required stan-dards and is more than adequate fornormal requirements.

To convert the AM to FM opera-tion is again a straightforward task.A small FM modulator circuit is in-troduced in which the microphoneinput line is lifted from the board atpoint 2 and inserted into themodulator/discriminator board. Themodulator used consists of a quadoperational amplifier in which thefirst stage includes an adjustablegain stage followed by a diode clip-per and a filter network using oneactive and two passive filters. Thecircuit and board layout for themodulator is given in the appendixand the output from the varicappoint is applied to pin 2 of the 7310when it is in effect in parallel with

the bridge of

6db/octave

\,18dboctave

300Hz 2800Hz

Fig. 13. Tailored audio response to achieve optimum value ofmodulation index at nominal 3.5kHz deviation max.

from some 20mV to 200mV. In effectthe design operates as a very effi-cient speech processor with a highdegree of distortion reduction at theoutput, and the audio quality ob-tained is of a very high standard in-deed. The design is based upon aMotorola concept drawn aroundtheir MC3401 device, whichoperates very effectively at 9 volts.

The low capacitance added tothe VCO by the varicap is compen-sated for by the control voltage sothat at resting frequency the desiredfrequency is not pulled and audiovariations across the diode cause agood quality FM signal to becreated. The only setting up re-quired is to advance the input pot to,

just below clipping level and to setthe output pot to the required devia-tion level. In some circuits theamount of VCO swing may not besufficient and in this case the outputfrom the deviation control may befed by a 1,u F electrolytic to the TP1connection at R201. In this case thedeviation will require steppingdown on the pot since it is now possi-ble to get up to 15kHz deviation.The signal sounds very loud butcould be frowned upon! Alter-natively the 100k resistor in the in-put could be by passed.

An audio oscillator of some50mV output at 1500Hz connected tothe mic input line acts as a suitablecheck for setting the deviation. Nor-

Mic in

100n

11 low mic output,may be omitted

1-200k

1M Check audio level

in 50k

2M2 2M2

Could bereduced to 1M

Vcc Vcc

Pin? GndPin14 +9VVcc +9V

Fig. 12. Modulator circuit used.

CR1. CR2 4148

4u7

IC MC3401

+9V

10k

....Compare audiolevels

(TD

VCO out

30p

1M

Vcc

50k resistors may be variedin ratio to give more o/p level

ITT -210

270k

600p

IVcc

750k

20k


mally it is not necessary to removethe modulation transformer but ifdesired C225 should be changed to200uF, and a bridge taken fromC223 to C29-5. The 12V line can thenbe taken across the original pins ofthe transformer from the 12V line tothe diode D207.

In the receiver the IF output istaken from the base of Q104 (secon-dary of the IF transformer) direct tothe board via a screened lead, thescreen acting as the earth return.The audio output is then taken to thetop of the volume control after liftingthe wire from the C 121/C 122 func-tion. This removes the AM detectorfrom the circuit but allows the AG Cand squelch to operate and keepsthe signal meter in circuit.

The device used in thediscriminator is the Plessey 6691, ahigh quality quadrature detectorwith its own built-in pre -amp andaudio circuit. The audio output isadequate to drive the normal AFamplifier devices found in the setscommonly used and gives an ex-tremely good performance with ahigh degree of AM rejection.

The use of a modulator anddiscriminator on the one board re-quires a degree of separation on T/Rsince the modulator can createaudio oscillation if allowed tooperate on receive. Accordingly, aT/R switching network which swit-ches the modulator on and thediscriminator off during transmit

put to the board ensures that at least3V must appear before the circuitswitches.

Prior to this the residual voltagewas capable of leaving themodulator on during receive.

For anyone wishing to convertan AM to set to the HO MPT 1320condition, the above conversionsare acceptable to the HO and pro-viding a Customs clearance form isfilled in and the relevant fee paid aset infinitely superior to the majorityof the so-called FM sets on themarket today can be produced. It iseasy to recognise a properly con-verted set since the audio quality isso superior to the normal 'muppetbox'.

The discriminator shown canonly operate at IF values up to1.5MHz or so and a suitable circuitand board layout for a higher IF us-ing a Plessey 6600 is shown inFig.14. In this instance the use oftracking oscillator techniques givesa superb AM rejection and verygood interference suppression sinceonly frequency variations arerecognised. By reducing the IF to100kHz a good audio output levelcan be achieved.

The AM rejection of thediscriminator normally used is verygood and the only adjustment re-quired is to adjust the core of thequad transformer for maximumreadability on the FM signal. Thisautomatically gives the best AM re

0 6-7 volts

10n

In 0-111710.7MHz

16

Fig. 14.

17

lOOOn

16 15

-IF300p

11. 13

. 2n 2

6k233k

12 111 10

10 595MHz

SL 6600

3

= =100n 33p 100n

VCO treqadjust

L.70 k

1.7k

Squelchcontrol100

k

4 k 7

Audioout

o Squelch

T4 n7

and vice -versa on receive is used.The T/R line operating this functionis derived from the coil side of R325.Due to circuit conditions a certainresidual voltage is present on thisline in the off position so the 3Vzener in series with the line at the in-

jection. Final adjustments are topeak the RX front end to 29MHz andretune the TX stages to the new fre-quencies.

The only other consideration isthe poor front end and early IFstages performance of the usual

receiver. By changing the front endRF transistor for a more suitabletype (choose one suitable for use upto 150MHz) with a slightly lowergain the cross modulation perfor-mance can be substantially improv-ed. The normal ceramic 10.7MHzfilter installed can also be changedfor a crystal filter (costing from £3 -.1.6) with marked effect on adjacentchannel performance. The crystalfilters have centre frequencies of10.695MHz. Appendix 1 shows thebreakdown into types of most of thePLL devices commonly used. Insome cases combinations of devicesare used as in the Sharps series,where a divider is separate from thephase detector. In the Sharps(probably the best of the older CBsets) the mixing technique uses two11MHz crystals for transmit andreceive offset. When the count con-version is carried out by simply lif-ting the grounded 64 pin and put-ting it to logic 1 the frequencyautomatically moves up 640kHz. Inorder to bring the 4.75kHz requiredto meet MPT 1320 into operation,simply cut the track alongside eachcrystal and place a 27pF cap acrossthe break. This shifts the crystals byabout 4.75kHz.

The codes used in three dif-ferent devices are shown in Fig.15.Only channels 1, 10, 20 and 40 areshown to illustrate the code se-quences but the patterns should beobvious from the sequence shown.

2" -... 64 32 16 8 4 2 1

0eric Channel Cod* IC pin NoNo Sum 9 10 11 12 13 14 15

PLLO2Apins718

high

1

10

2040

746301111115030

I

01100100

7 bit

0

0

straight

0

1

1

1

binary

0

1

1

1

0

0

Powers of 2" 4 2 1 8 4 2 1

Pin No 13 14 IS 2 3 4 5

M5042502pin12high

1

10

2040

0.11225010010145

7

0

0

1

bit binary

00

0

0

'

0

coded

00

0

00

1

decimal

0I

0

1

0

1

Powers of 2"

Pin No

2

6

1

5

8

4

4

3

2

2

1

1

LC7120

1

10

2040

0 11.02000

6 bit

0

01

0

binary

01

00

coded

000

0

000

0

decimal

0

000

I

00

0

Powers ofPin No -

2 not used17 16

in logical15 14

sequence13 12 11 10

TC9109

1

10

2040

111111111

1

0

8

1

01

bit

3

1

U

random

00

0

cod*

00

0

1

1

1

000

000

Showing code distribution in ditterent modes

Fig. 15. Powers of 2

And attempt has been made tobring about three objectives:a) To stimulate interest in buildingsomething yourself at low cost.


b) To create activity on 29MHzbefore someone moves in because oflack of operation on the band.c) To find a use of discarded CB setsnow that new reforms are being in-troduced more stringently.

With minor variation the abovetechniques have been applied toSSB rigs in an effort to simulate

mobile activity on 10 metre SSB.Many CB aerials can be retuned

to 28-29MHz with little difficulty anda host of reasonable test gear at verycheap prices is also available.

To date some 2 - 3000 conver-sions to 27MHz FM have been madeto a variety of sets and basically thesame technique applies to 29MHz.

Appendix 4

Binary ArithmeticBinary arithmetic is an arrange-

ment of numbers in ascendingpowers of two.

The standard arrangement is asshown in the table across the page(below).

Power of 2 0 1 2 3 4 5 6 7 8 9 10 11 12 2'

Binary No. 1 2 4 8 16 32 64 128 256 512 1024 2028 4056 Code sum

Sample 0 1 0 1 1 1 0 0 1 1 0 0 0 826

Appendix 1

Codes UsedBinaryInputs

CC 13001CC 13002LC 7113MC 58472'MC 58473PMB 8719MB 8734MC 145104MM 55104MM 55114MM 55124MN 6040 ASM 5104MC 145106MM 55106MM 55116MM 55126MM 55108SM 5118MC 145107MM 55107SM 5107MC 14568MC 14526MC 145109PLLO2A /AGSM 5109TC 9100PMSM 5807MSM 5907MDC 40013NIS 7261ANIS 7264BPLLO1APLLO3AREC 86345TC 5080PTC 9102PTC 9103PPLLO8A

Binary inInternalROM

LC 7110

in VariouBCD inBCDCodeConvertor

LC 7120UPD 861CUPD 2810CUPD 2812CUPD 2814CUPD 2816CLC7137

RequireSynthesiserReplacement

s P.L.L. DevicesRandom

ProgrammeInputs Code

LC 7130 TC 9106PMSC 42502P TC 9109PUPD 858C

LC 7131LC 7135

RequireSynthesiserReplacement

As can be seen if each levelcould be selected and shown as be-ing used by indicating as 1 whereasunused lines were indicated as 0then any number between 0 and8111' could be shown by using theabove sequence. A typical arrange-ment showing a count of 826 isshown, ie the sum total of 512, 256,32, 16, 8 and 2.*8111 = sum of all values shownfrom 4056-1.This system is known as straightbinary. One other form is used inthe systems discussed in the articleie. Binary Coded decimal or BCD.In this case only symbols up to 23 areused as number indicators, eithertwo or three additional channels areused as decimal point indicators,and multipliers.

Rec

VAnt 0104

26 965 10 695 0 455RF amp Con V1 Con V 2 MHz IF amp Oct AntMHz MHz

0101 0102 010501030101. D105 0106

Rx.VCO 16 27 to16 71

PL,. ICIC202

Channal sw

LED sw

1 I

1 I I I

/ 1_1 0

AGC

+e

oRx

-eW.10 24MHz

VCO

1/2 IC203

16 725MHz Mixer

1/2 IC203

26 965MHz RF amp

0301

Mic

Filter

SQL

0201

RF drive

Q302

ALC

C1202Filter

RF power

0303

Audiopower

IC201

Leveldetector0203

LC filter

Appendix. 2. Showing circuit path of tranceiver chosen as sample

Rect0302

Sp

To anti-


Power of 2 3 2 1 3 2 1 0 2°

Binary No. Codesums

4 2 1 8 4 2 1 Code sum

Sample 0.6 0 0 0 0 1 1 0 6

numbers 1.6 0 0 1 0 1 1 016

shown 2.6 0 1 0 0 1 1 0 26

3.6 0 1 1 0 1 1 0 36

4.6 1 0 0 0 1 1 0 46

The BCD format shown is a 7 bitcode but obviously by using two col-umns only in the left hand group* a6 bit code counting 0-1, 10-19,20-29, and 30-39 could be used ie atotal of 40 lines using 0 as a signalline ie absence of all signals or a No.

Many other forms of binary codeare in use but the ones shown aremost commonly used. The so-calledRandom Code is a selective code us-ed in certain devices only as asignalling technique rather than asignificator technique and is actual-

ly only semi random.From the above it is apparent

that signalling is either by an on oroff situation and can be effected bysimple switching techniques. This isthe principle by which the program-med instructions are issued to thephase lock loop devices.

For similicity of explanation thefirst table above is shown as readingleft to right. It is more conventionalto present the table reading right toleft as shown in the second table andin Fig. 15.

Appendix 3. Basic block diagramof dedicated device.

Appendix 5. 5V regulator

PROP A L BAILEY G3WPO WPO COMMUNICATIONS

''" '80metreDSB80107 included

pNLY £31.46 incCopy of HRT article

3W + BOMBPROOF PA 12V OPERATION VFO CONTROL IDEAL FOR BEGINNERS/CLUB STRAIGHT FORWARD ASSEMBLY

COMPLETE BOARD KIT with d/s drilled board, ALL components (exceptoptional meter), VFO cap, slow motion (6:1) drive, wire, etc, etc. Needsonly Hi -Z mike, speaker and + 12V to get YOU on HF. Experience theworld of QRP with this excellent little project, capable of DX results witha reasonable aerial.ALSO:A READY -PUNCHED SCREENED case,with all hardware inc knobs, sockets,screws etc (no speaker) * the meter foronly 08.66 inc.

"160M version now availableDSB160 - SAME PRICE

AS FEATURED INMARCH 1983 HAM

RADIO TODAYAll our prices include VAT and p&p.Allow 1-3 weeks for delivery.

MAIL ORDER ONLY.

LARGE SAE brings more info anddetails of other kits:2M FM 6 CH Monitor RX Kit £30.65IAMBIC Keyer Module (Built) £20.65RX80 ATU (Kit) £24.92VHF Prescaler (Kit) £5.49Capacity measuring add-on for

DFM's (kit) £12.65

We also manufacture equipmentfor blind operators including a

Talking DFM and automatic VSWR/power meter. Write for full details.

20 FARNHAM AVENUE HASSOCKS WEST SUSSEX BN6 8NS

RATEC 83Radio Rally22nd May

South ManchesterRATEC announce this NEW venue for

ManchesterLocated on the A5102 in Woodford, it is withinthree miles of the M56/63 motorways. Situated ina rural setting just off the A34.Up to eighty traders have been invited to attend,offering the widest range of interest to the ama-teur, and micro enthusiast.Opening from 11.00 am, and closing at 5 pm, therally will have the following facilities.* Talk in on 145.550MHz FM.* On site catering, and bar.* Overnight camping, and caravans by

arrangement.* Large parking areas.* Professional security guards.* Attractions for wives and children.

Admission 50p (Children under 16 Free)For further details of this prestigious event.

contact:David G3VFP, on 061-439 2377.

Or sae to:17 Laleham Green, Stockport SK7 3U.


ELECTRONICP IIVIL SERVICES2 ALEXANDER DRIVE. HESWALL . WIRRAL. MERSEYSIDE. L61 6XT

Teiephoric 051 342 4443 Telex 627371

PRICES EXCLUDE VAT - U. K. CUSTOMERS PLEASE ADD 15% VAT

CRYSTALS MANUFACTURED TO ORDER TO AMATEUR SPECIFICATION6 to 9.9999kHz HC13/1.110 to 19.99kHz HC13/1/20 to 29 99kHz HC 13/U30 to 59.99kHz HC13-U60 to 79 99kHz1-1013 U50%, 99 99kuc HC13 U10010 ' 41? alC13150 HCE* u150 399 5,1.: ..ce L.4:20 :.: 4995C'Z' -99

-ze

£32.80£31 00£23.08£21.73£15.69£13.08£11.32£11.32£7.83£7.00£7.83

£11.01£11.25

1.5 to 2.59MHz (fund) HC6/U2.6 to 21 MHz (fund) HC6/U3.4 to 3.99MHz (fund) HC18 & 25/U4 to 5.99MHz (fund) HC18 & 25/U6 to 21 MHz (fund) HC6. 18 & 25/U21 to 25MHz (fund) HC6. 18 & 25/U25 to 28MHz (fund) HC6. 18 & 25/U181c63MHZ(30/1)HC6.181125/U6010105MHz(50/1)1-1C6.18825/Uip5to 25MHzt5OrT1HC18825/U'25to147MHzt7011HC15625/U50tc179MHzi90 TIHC18825/U

-5to:50f0H:zi90 TIHC18825/U

£5.38£4.87£8.75£5.36£4.87£7.31£9.00£4.87£5.81£8.44

£11.25£12.88£13.50

TOLERANCES:.:.ea-se = -.L. 00V.- C +T0 C.e = = 300pn, -10 C to +60 C

Unless otherwise specified fundamentals will be supplied to 30pf circuit conditionsand overtones to series resonance.DELIVERY: es- S AetkS Prices ShOwn are

c -e . s_ e: ss: : :se a^:es asadaele. Pleasesera -S :' EZ.

COMMERCIAL AND PROFESShill ,z4S-Ez

s:: .-

to60MH: "s -a z_s-:an even faSte' E PRESS SE=. .7.*E::-amecommerc.a: :a: c -s e; ::: 'your neeas ancl se^z a za:-.e a. a,Engineer Mr NcrC.Pe a- s -c -a - -e . :e6.30 p.m

IONAL CRYSTALS

_ :a: :-s t -e rarve MHz\-7--.1C -3835 Nea,sonase

:e" .%e :a- a sz zls:als for.e-, : .2 :7' CeS kne....

:e e:-:-e: :e :- Saese -z_ es ce:e.ee- 4.30 anc

DOUBLE BALANCED MIXERWe are nowstocking two nea .e, a -E e AMD108 we used to stock and also Me SBC c...! â .e

-s-ce sce.: ' -g

500 kHz. to 500 MHz The M8 .s ê -"et ca sea ec - f7 83 '."e s ^:^sealed ,;1 £6.09.

4 METRE, 2 METRE AND 70 CENTIMETRE STOCK CRYSTALSWe stock crystals for 7026MHz on 4m On 2m .e stock RC -_S18 thru S24. For 70cm we have RBO thru R815 pas SI.:5 5..SU20. For full details of the above stock crystals plus oefa, 5Converter, Marker and Alternative IF crystals crystal sockets a -cAERIAL RANGE see May 1983 Ham Radio Today. page 65 or se,c SAEthe above address.

Intermedial Ltd'3 Beech Avenue. Easlcote Ruislip Middy HA 4 8UG Tel 01 8664641

PLL TRANSCEIVEV.F.O.

Converts any surplus radio telephone into a continuously variable F.M. transceiver. Microphoneis connected to unit and a stable 2 metre F.Msignal is available for driving the amplifierstages. On receive the unit produces a local

PRECISION LOCATORSET

With the accuracy of a computer program(tolerance less than .5%1, this map and rulercannot be compared with ordinary locatormaps.

Ruler can be fixed at 0TH Size 30 x 42%inches, scale 1:3 million *Printed in 4 colourson washable plastic *Metal top and bottomstrips *Approved for contests Full directionsDispatched in sturdy cylinder. £9.90

oscillator signal 10.7MHz below signal frequency.600KHz repeater shift Suitable for other I. F.'sExtension for digital display Kit includes allcomponents (exc 3 Xtals and xercol 8 pagesof directions. E14.90 (directions only £0.95)

XTALS 46.56MHz 46.36MHz 43.00MHz £17.15

C WO All prices incl VAT p&p (within U K

THE Co CENTRE10 MERTON PARK PARADE,

KINGSTON ROAD, LONDON SW19(JUNCT. MERTON HALL RD)TEL 01-543 5150

LONDON'S NEWEST AND BRIGHTEST EMPORIUMNEW

PRODUCT30 foot mast

telescopicideal for

portable use£28.00

TRIOYAESU-ICOMStandard-FDK

Azden-JaybeamWelz-DaiwaTono-SMC

KDK

SLIM JIM2 metres70 cms

Complete with4 metres co -ax

£8.50Inc. P PY

INSTANTCREDIT NOWAVAILABLEup to £1000

throughLombard

Tricity

NEWRANGE

JUST ARRIVEDDaiwa Cross

pointer metersantenna tuners

etc.

THE NEWG4HXZ

MORSE TAPEInc. 2 simulated

Morse Tests£5.50

Inc. Ps -P

GOODSELECTIONof R.S.G.B.Publications

Now In Stock

URGENTLYREQUIRED

Working or notall s/hand eqpt.

Try us lastwhen selling

your gear

NEWPRODUCT

23cms A.T.V.Receive converter

just plug intoyour home TV.

£29.50Inc. P +-P

HB9-CV2 element2 metre or

70cms BeamNow available

Mail Order£9.50

LARGESELECTIONof lashing kitPoles -ClampsRotators -CableJaybeam-Tet

Tonna-etc.

THENEW SX-200N

VHF UHF Scanner£265.00 also the

new MagnumVHF Receiver

Lo -hi Band£99 Inc.

THEFULL RANGE

of theMicrowave Module

ProductsAvailable

BARCLAYACCESS

ETC.MAIL AND

TELEPHONESERVICE


Taking to the

They say that history repeats itself. Itcertainly did so in my case withwhat, to me, were surprising results.About fifteen years ago I was intro-duced to a guy with a peculiar hob-by. He spent all his spare time and anot inconsiderable amount of hisspare cash in talking to people. Notmerely to the neighbours. Not evenjust to those he knew. Oh no! Thisguy delighted in talking tostrangers. Not merely to thestrangers he met in the street but tostrangers all over the world. Hisexplanation that he was a radio'ham' having produced instant men-tal images of the late, great TonyHancock, I was greatly intrigued tolearn more of the rites and mysteriespractised by the devotees of thisstrange cult.

Taking the plunge

The result of this gentleman'sbest efforts was that one bright Mayevening found me lining up withabout a hundred other hopefuls,prepared to do battle with the evilgenie from the City and Guilds.having sailed merrily through partone, Welsh caravans and all, I satdown to part two, happy in the beliefthat I could cope easily with almostanything which my inquisitors mightdream up . . A belief which greweven stronger as I realised that I wasable to answer the first few questionsat a glance.

My balloon burst with one hellof a bang! Suddenly, from aboutquestion seven I was faced with along string of questions whichappeared either ambiguous orimpossible and which had me grop-

ing for the right answers. in a stateof advanced shock I even attemptedto discover the total resistance in aparallel circuit by adding togetherthe individual component values.Somewhat dazed, I emerged fromthe exam room at the appointedhour and lost no time in joining anumber of fellow sufferers in aheadlong dash for the nearest tavernin a vain attempt to wash away thememories of the last few hours.

Even worse

Worse was to come. Undauntedby his efforts to impart a basicunderstanding of radio theory andfar more confident of my successthan I felt, my erstwhile instructorconned me into accepting yetanother challenge. Exhibiting con-siderably more confidence than I

really felt, I accepted his assurancesand embarked upon the task oflearning Morse before the examresults were published. Again to mysurprise his abilities matched hisbelief and my pleasure knew nobounds when, within a few days oflearning that I was indeed entitled toapply for an amateur's licence I

received a Morse test pass slip.Besotted with my new-found

power, I decided to spend a fewquid, then, armed with my allsinging, all dancing, FT48OR I

discovered the next pitfall. It seemsthat the Home Office did not sharemy eagerness for the world to hearmy dulcet tones, with the result thata very frustrating ten weeks were topass before my ambitions wererealised. Ten weeks during which Iand many of my former classmates

by Keith Townsend G4PZA

were to develop an entirely newdisease which affected the musclesin the thumb whenever it was placedwithin touching distance of amicrophone. All in all I reckon that Ispent more time in waiting for theresults and then the licence than Idid in studying to become a radioamateur.

At long last it happened. I

arrived home one lunchtime to findmy new licence waiting for me. Inthe ensuing confusion it took me agood five minutes to find thecallsign, which I then repeatedsilently to myself a few hundredtimes, just to make sure that it cameout right on the air. Since I spendmost of the working day in my car Ihad fitted the rig to it long ago so,lunch forgotten, I returned to thecar, plugged in the mike and mademy first, very hesitant call. Uttersilence! Either the band wasdeserted during the lunch hour,(was there any thing in the licence .

conditions to this effect?) or theseamateurs were a damned unfriendlybunch. My second and thirdattempts having met with an equallack of response I returned, disap-pointed, to a now cold lunch.

First contact

Fed and rested, I decided togive it one more try before decidingwhether to sell the whole issue andbuy an exercise bike. Whether I wasmore cautious this time, or simplyless eager I don't know. Anyway Idecided to check over the rig beforekeying the mike. There, right infront of me, was the cause of my


earlier disappointment. In the midstof my self-congratulation I had leftthe damned repeater offset in.Having rectified this error, which Ifreely admit to having repeated on afew occasions since, I soon foundmyself in conversation with twofellow novices and we were alldelighted by the friendly receptionand encouragement which wereceived for a few older hands dur-ing the course of our chat. Probablythe strongest single impression I

have gained during my first fewweeks on the air is of the strongcameraderie which exists amongradio amateurs and the lengths towhich they will go to extend a warmwelcome to a newcomer.

The next task was to constructand erect a suitable antenna systemfor use at home. Armed with whatseemed like miles of aluminiumtubing, a rotator and an odd assort-ment of tools it was not long before Iwas finally in a position to attemptsomething more ambitious than themobile contacts which were all thatmy log contained up to now.

A quick CQ call on two metresideband met with instant response.At last I had my first real oppor-tunity to work DX as all the LEDsbegan to dance at once and a voicecame blasting through the speaker.If you regard two miles as DX thenmaybe I had achieved my objective.Undaunted, I tried again. This timethe result was far more encouragingand I found myself in conversationwith an experienced sidebanderover a hundred miles away. What'smore I did so without the half -expected howls of protest from theXYL, watching the box in the nextroom.

HF near disaster

My first visit to the HF bandswas a near disaster. Hearing aRussian station calling CQ on tenmetres I waited for a pause then,eagerly attempted to answer hiscall. So nervous was I and soanxious to pronounce both of ourcallsigns accurately, that it took mea few moments to realise that,despite the pressure of my thumb onthe PTT, my Russian had beguncalling CQ yet again and what wasmore I could clearly hear him.

A quick dash for the solderingiron and we were soon back inbusiness, faulty microphone lead

reconnected just in time for a fur-ther break in transmission from theUK7 station. My answering call wasreturned immediately, accom-panied by an irate delegation ofavid commercial watchers from thefront room. Promising to look intothe TVI as soon as my contact wasfinished I called my Russian again.Within seconds of his coming backto me the entire ten metre band fellflatter than my chances of winningthe pools. I can only assume that theKGB did not want an innocent com-rade to be corrupted by talking to atrouble -maker like me.

don't you think it would help,dear, to switch it out of repeater shift"

At this stage I had not attemptedto use CW on the air, though, like anumber of my colleagues I had con-tinued to attend the local Morseclasses in the hope of increasingboth my speed and confidence. Itrather surprised me to learn that Iwas not alone in my reticence toappear on the key for real and so asmall group of us decided to try afew short QSOs among ourselves. itis one thing to read and send simplemessages in plain language andquite another to understand theshorthand of the airwaves, so wekept our messages short and simpleto begin with, venturing into moredetail only as our confidence begainto grow. These simple experimentswere perhaps the most valuableform of self -instruction we couldhave devised and certainly did agreat deal to ensure that when wefinally took our courage into ourown hands and joined the rest of theCW fans we would not simply clutter

up the bands with a load ofunintelligible rubbish. it is a methodwhich I would recommend toanyone interested in CW, perhapsthe most rewarding of all modes oftransmission. To those who see theMorse test as some kind of hurdle Ioffer the observation that it is fareasier to pass than you might think.Nobody could be less certain oftheir abilities than was I when Iarrived at the test centre, only tofind yet again clear evidence of thegenuine friendship which existsamong radio amateurs. Those con-ducting the tests do everything intheir power to create a friendly,relaxed atmosphere, in which thetest is far less of an ordeal than I hadimagined possible.

Repeaters are not really myscene though, since I use the roadsa lot I have made use of them on afew occasions. A trip into the heartof London brought me considerableamusement, as the inhabitants ofGB3WL guided me through un-familiar streets, ably assisted by oneor two squeakies who, upon hearingthat I needed some assistance,promptly stood aside until I reachedmy destination. They even had thecheek to ask 'Ave yer dun?' as I

signed. My thanks go out to all con-cerned.

One of my rare visits to my localrepeater, GB3BM, in search of afriend who could not be located onS20, found me talking briefly to aDutch station. Though this iscertainly not what repeaters are allabout, I was very pleased by theoccurence, since at the time I hadspoken to nobody outside my owntown, much less overseas.

First impressions

So what are my first impressionsafter only a few weeks as anamateur? Frankly, I reckon I wastedfifteen years. I should have becomean amateur at my first encounterwith the hobby. I have not yet fullygrasped the range and the scopewhich my licence has put at mydisposal and each attempt to use anew mode of transmission brings itsown fascination. I have yet to tryeither RTTY or ATV but I seeamateur radio as a hobby which Ican develop over the next thirtyyears. My station will develop as myfinances permit and as myknowledge increases. 41


RADIOYESTERDAYTWO -LETTER CALLSIGNS ONTHE TARMAC

.7,

By Jack Hum G5UM

One of the famed two -letter call -signs of the Nineteen Twentieswas 2FG, that of the late LeslieMcMichael, founder of the firmbearing his name. This historic53 -year old picture (it sums upthe sartorial elega'nce of the age)shows 2FG fourth from right.Fourth from left is the McMichaelsales manager, the late GusAllen, whose callsign G8IG wasfamed throughout the DX corners

of the world. The photographwas taken on Boat Race Day,1930, on the concrete apron atCroydon Aerodrome (the newfangled term 'airport' was barelyknown this side of the Atlantic inthose days). As an enterprisingpublicity man G8IG would hirean Imperial Airways 'Argosy' air-craft every Boat Race Day andfill it with radio trade notabilitiesand pressmen generally, plus a

There wasa time whenthey were alltwo -lettercallsigns

..ustkw.

selection of McMichael portable'wireless sets' to enable all onboard to hear the BBC Boat Racecommentary while they wereskyborne over the Thames, at thesame time watching the progressof the University boats belowthem. The wood -and -canvasairliner chartered on such occa-sions can just be seen in thebackground.

"Is that yet another of them?". WifeGrace's voice came wafting up thestairway. In her kitchen below theradio room she hears through thefloorboards much of what goes onduring the G5UM operating ses-sions.

It was indeed "another one ofthem", probably the sixth that week,who was mystified by the two -lettercallsign which was calling him.

"Go on, tell him you're not aforeign body!" came the voice upthe stairway with a light chuckle.Upon which G SUM turned the

transmission back to the personwaiting at the other end of the 2mlink and patiently explained that,yes, there were only two letters afterthe numeral, and that, no, it wasn't avisitor's licence: the reciprocal hadthree letters after the numeral, nottwo. Did not the person at the otherend have a Callbook in the house?No, he did not, clearly one of manyhundreds of new licence holderswho had still to learn that TheCallbook is perhaps the second mostimportant document in a metrewaveman's kit after his logbook.

Politely the distant communi-cator replied that he had thoughtabout getting a callbook when hisown callsign was likely to appear init (inviting the riposte, hastilysmothered, that it's not your callsignyou want to look up: it's the otherparty's, all several Liousand ofthem).

"Oh, well, when you do getyourself a callbook you will find thatthere are still a few G -Five-plus-twos listed in it (not to forget a fewG -Six and G -Eights who are notClass B licensees) plus quite a few


G -Twos, G -Threes and G -Fours, allwith two letters after their respectivenumerals".

The story in more detail wouldhave taken the better part of an hourto explain to Polite Communicatoron Two. If there had been time andfewer operators clamouring to usethe frequency on which all this wasgoing on (or if Polite Communicatorhad had 433MHz where more timeand space exist) the story wouldhave gone something like this:

At the very dawn of amateurradio in Britain the few hundredenthusiasts playing dangerouslywith spark -gap transmitters and lessdangerously with crystal receiversused three -letter callsigns whichwere often self -assigned. AfterWorld War 1 when amateur radioenjoyed a second dawn the alloca-tion of callsigns was put on to a moresystematic basis. From the Twentiesonwards British callsigns consistedof a numeral plus two letters, eg,2L0, 5XX or 6BM (the 'Twos', the'Fives' and the 'Sixes' were issuedcompletely at random). This processwas expected to yield almost twothousand callsigns, which in theview of the Licensing Authoritywould last into the indeterminatefuture.

j. H. HUM,

o

How wrong they were becameevident from the fact that within 16years nearly all of the G 2 -plus -two,5 -plus -2 and 6 -plus -2 assignmentshad been exhausted. The next call -sign block to be issued - and thiswas in 1936 - was the G8 -plus -2 -not a Class B licence: that particularconcept was still 28 years into thefuture and World War 2 was yet tointervene.

Back then in the mid Thirtieseven the G8 -plus -two series was tobecome rapidly completed for thegood reason that radio communica-tion technology was by then trulyforging ahead, inter -Continentalcontacts were common - and therewere even people using the esotericmetre -wavelengths with the aid ofself-excited oscillators and super -regen receivers! It was evenrumoured that television was com-ing along. And so as the G8 -plus -twos ran out the G3 -plus -two serieswas initiated followed soon by theG4 -plus -two, a callsign block nevercompleted: the start of World War 2cut it short.

Holders of the earlier 2, 5 and 6permits (yes, it was a Permit in thosedays, not a Licence) were not allow-ed to use the national prefix of 'G'except by express authority from on

(

17,EASTWCV RD., LONDON,

HIRT

N.10.,

N"

ENG.

To Rad i.ct r. .......... i-o r ...... .... . .. ...... role via. Ittwe .... .. . t-. .............

-

1 ...............N...

.....................

ARK, .....................

. ....... .........

t c c r : st 7 a ig It

Transmitter :at..1/..0 .... . . vo/ts

Aerial :- two

ftentarks ........

Pso QS LIL, Tnx Hoi CUAGN.

.......................... tvcits input

tit../ ......igh.

.... ......................................

73 ...................... ................................

No national prefix of 'G' on thisearly QSL card used by G5UM(strictly 5UM) from his originallocation in north London, wheregas mains were the rule, electricpower came much later, and

your HT power source was a str-ing of dry batteries. You went offthe air while your LT powersource, a 2V accumulator, wasaway at the local garage to becharged.

high, and then only if they statedthat they proposed to use wave-lengths capable of reaching outsidethe home country. Gradually, thisrestriction was eased. Stations inEngland were allowed to use theirnational prefix of 'G' and in Nor-thern Ireland 'GI'. For someobscure reason Scotland initially us-ed 'GC', possibly for 'Caledonia'.All other components of the UnitedKingdom were expected to use 'G';it was not until much later thattoday's variants of GW, GD et alwere to be heard.

Readers with long memories willhave detected some significance inthe callsigns of 2L0, 5XX and 6BMquoted above: they belonged to theBBC, who until the British Broad-casting Company became the 'Cor-poration' in 1927 were assignedamateur -style 'idents'. Very few ofthese have been reallocated toprivate radio amateurs. An il-lustrious exception is 5XX, the call -sign of the mid -Twenties radiated by'Daventry long wave' and today fin-ding new expression as G 5XX, thecallsign of the Daventry Ariel RadioClub.

Echoes from the past

Many other callsigns of yester-decade are tending to find newleases of life, often in a collectiveidentity with radio clubs: G2XV, thecallsign of a famous Cambridgepioneer of the Twenties, GeraldJeapes, now belongs to the Cam-bridge club, and G 6CW, once own-ed by the late John Curnow, hasbeen taken up by his local club inNottingham.

Another NottingHAM who hasrevivified an old callsign is MikeMansfield, who upon passing hisMorse test relinquished his identityof G8RXU and took up his grand-father's callsign, G2SP. Down inHertfordshire much the same thinghappened when G2PA reappearedtwo generations after the notedpioneer components firm of G.Z.Auckland & Co originally 'aired' itfrom their City of London premisesback in the Twenties - and G2PA isstill an Auckland.

There is a sprinkling of others.Their numbers will increase as old-timers quit the callbooks and theirdescendants pick up their two -lettercallsigns to breathe new life intothem once more.


Taking apartthe

FTDismantling the FT101

Some circuit boards and partsare easily accessible once the lidand bottom covers have beenremoved. When servicing in themore difficult to get at sections, it isnot worth struggling and risking do-ing damage, as it is very easy toremove the complete cabinet. To dothis, proceed as follows:1. Completely disconnect the

FT101 from the mains, aerial andall other equipment and place onbench in an inverted position.

2. Remove bottom cover andrelease hexagonal screws andtwo star -headed screws (four atthe front and one at the rear)holding cabinet in place.

4. Gently slide cabinet off over rearof FT101 ensuring that the lidcatches do not foul the audioboard or the metalic labels iden-tifying this board's preset con-trols.

Faults and modifications

Mains fuse blows. If a replacement3 amp fuse fails do not fit a larger

Troubleshooting and repair

by Harry Leeming G3LLL

one: there is a fault. The most likelycause of mains fuse failure is a shortcircuit in the HT rectifiers, andthese should be checked with anohm meter. A suitable replacementis the BY127 television type HT rec-tifier, and it is advisable to replaceall eight rectifiers in the HT bridgeeven if only a couple are faulty.Note that early FT101 Mk Is usedonly four HT rectifiers, but forreliability these should be replacedwith eight rectifiers fitted with the470k equalising resistors as in Fig.1.

Set works on receive, butwon't transmit, or vice versa. Acommon cause of this is that thejunior operator has had his fingerson and has left the INT/EX/CHswitch in the wrong position. ManyFT1Ols have been returned for this.

No transmit, no PA current,receive OK. Check that poweramplifier valve heaters are lit. The11 -pin plug at the rear must be fittedand must have a link between pinsone and two before the poweramplifier stage will function.

No SSB transmit, three or moreS -points down on receive, finalamplifier resting current OK at 50to 60 mA. CW and tune gives fulloutput. This fault is occasionallycaused by Q1 on the IF board hav-ing blown. You can replace this FETwith almost any RF FET such as theMPF102, provided that you get thepin connections correct.

Any weird fault, particularlyif intermittent. High resistancecontacts on the plug-in circuitboards can cause some very odd ef-fects. Standard service procedure isto remove the plug-in circuitboards, squirt the contacts with con-tact cleaner, and plug them in andout half a dozen times to clean theconnections.


240V AC

480V

240V AC

4n7

470k

470k

470k

470k

470k

470k

0 +600V

470k

470k

4n7

5R6

Fig. 1. HT rectifier circuit in most FTIOls

Fuse blowing but HT rectifiers OK.Try operating the rig with the poweramplifier valves removed. If all isOK, leave the valves out andmeasure the bias voltage at the gridconnection of the power amplifiervalves. This should be about - 50Von transmit or -65V on recieve.Turn the band change switch and ifthe voltage falls below this, or evengoes positive on any band, replacethe relevant coupling capacitorfrom the anode of the driver valve.Note that a coupling capacitor of 80or 100pF goes direct to the anode,whilst other capacitors are switchedin parallel with this on 160m and80m in some models. A short circuithere will have ruined the PA valvesso once this fault has been cleared itwill be necessary to fit new ones.

Fuse still blows, but PA andHT rectifiers OH. Sometimes theDC/DC inverter ('chopper') tran-sistors go short circuit even if the rigis never used on a 12V supply, andcause fuse blowing. The FT101 willwork perfectly on an AC supply withthe chopper transistors discon-nected, hence the easiest way to testthese is to disconnect them and try anew fuse. If these transistors arefaulty, the cost of replacement is inthe region of i.20 to AO a pair. If youdo not anticipate DC operationsimply remove them.

Fuse still blows! If all the sug-gested tests come to nothing tryoperating the FT101 from a 24V ACsupply. At such a low voltage even abad short is unlikely to blow the fuseand every output of the rig's powersupply should give one tenth of itsrated voltage. Find the power supp-ly output that is less than this andyou are in with a fighting chance ofdiscovering the cause.

ALC faults

Valves operating in class AB1 do notpass grid current until they areslightly overdriven. In the FT101any grid current caused by over-driving is rectified and fed back as anegative ALC voltage, rather likeautomatic gain control on a

receiver, and so turns down the gainof a previous stage. In practiceslightly over -driving a class AB1amplifier does not do any harm andthis system is used in much amateurequipment and works well.

No ALC indications. This isalmost always a result of low drive tothe power amplifier valves, and iscommonly caused by an agingdriver valve or misalignment.

ALC too active on one or morebands on some FT101's. The trou-ble here is usually caused by theradio frequency choke L12 pickingup RF from the PA coil. The simplecure is to replace the choke with a2.2K resistor. Only a limitednumber of FT101Es used this extrachoke L12. Later FT101Es revertedback to the original circuit, see Fig.2.

No transmit, ALC meter 'pings'hard over and is not adjustable.This fault is caused by a short circuitALC transistor (Q1 on mod andoscillator board FT101 Mkl, Mk2,B, EE, EX and E Mark 1; or Q6 onprocessor on FT101 Mk2 and Mk 3).This fault may have been caused bya flashing PA valve or a leaky ALCcoupling capacitor. As a replace-ment FET, an MPF102 will do if youget the connections right, or youcan fit the 'spare' FET in the fixoscillator circuit which you areunlikely to use.

Set intermittently dead on oneband, often 15m. This fault is usual-ly caused by the first conversioncrystal oscillator refusing to start.Slightly adjusting the relevant trim-mer (see manual 'heterodyne crystaloscillator alignment') will usuallybring it back to life again. Themanual suggests adjusting using a

TO GRID CIRCUITOF PA VALVES

BIAS

(a) The troublesome ALCcircuit used onsome FT101Es

ALCOUT

TO GRID CIRCUITOF PA VALVES

(b) Circuit used onGRID other models & most 'E'sCHOKE

BIAS

Fig. 2 ALC Circuits

2n0ALCOUT


diode probe volt meter, but in prac-tice turning the trimmer theminimum amount needed to givereliable operation of the oscillator isall that is required.

Receive signals and calibratorvery weak but sounds lively andtransmits OK. This fault usually in-dicates that Q1 on the RF board hasblown. It can be replaced with anRCA 40673 or 3N201 etc. If thereplacement blows suspect that the12BY7A driver valve is flashing overand damaging it.

Receive audio quality slightlybelow par - a bit 'gritty' FT101BMk2 - FTIOIE. If you suspect thereceive audio quality, try adding anextra earth wire to the audio IC asshown in Fig. 3. If there is an im-mediate improvement leave thiswire in position.

Fig. 3 'Gritty' audio: add extraearth wire from printed circuitto screw as shown

Preselector peaks at differentpoints on receive and transmit.This could be an alignment fault,but it also occurs if the wrong makeof 12BY7A driver valve is fitted. Usea Toshiba or an NEC valve in thisstage.

Drive slightly low on 10 and15m even with new valves andafter full alignment. This faultsometimes happens when theoriginal Toshiba valves have beenreplaced by NEC, as these usuallygive a fraction less gain. ReplaceR22 in the RF unit (was 56 ohms)with a 22 ohm resistor. Thismodification is introduced by Yaesuin the last production batch ofFT101Es. A little extra drive canalso be obtained by turning VR1 onthe RF unit the minimum amountthat is needed to produce maximumoutput.

Transmit and receive frequen-cies not coinciding. This is a simplealignment problem. Set VFO in ap-proximately mid -position and con-nect a general coverage receiver toa short length of aerial wire, andpoke its insulated end through thecentre of the eight pin VFO socketon the rear of the FT101. Tune thegeneral coverage receiver around9MHz and you will pick up the VFOof the FT101. Adjust the position ofthe length of pick up wire until thesignal is about S9, and in the CW orSSB position of the generalcoverage receiver tune in a steadybeat note. With the heaters of theF7'101 switched off wait until thingsstabilise and any drift stops, andwith the clarifier in the off positionswitch from PTT to MOX and thebeat note should not change. If thenote does change adjust the zerocontrol on the regulator board untilthe note is the same on transmit as itis on receive. When this has beenachieved switch the FT101 toreceive and adjust the preset controlmounted at the rear of the clarifierunderneath the chassis until thenote is the same with the clarifier offas it is in the central position. Theseadjustments should be repeated un-til the note does not change with therig switched to transmit or recieve,with the clarifier on or off.

Main tuning very lumpy orloose. The main gear box seldomgives trouble but the 6/1 epicyclicdrive does wear or dry out after con-siderable use. This bit of the FT101is available quite cheaply, as(believe it or not) it is made forYaesu in the UK. Whilst no doubt itcould be cleaned and regreased it ismuch less trouble to swop it. Lay theset on its rear with the tuning knobpointed vertically and the bottomcover removed. Once the main tun-ing knob has been removed, how toremove the drive is self evident, butnote the order of the variouswashers as you remove them. Other-wise, putting it back together againmight not be as simple! While youare at it put a little grease or oil onthe gears in the main gear box.

VOX operation - all models.The VOX has a tendency to 'hangon', especially if you talk too longwithout a breath! Much less criticaloperation will result if D3 and DIare shunted with resistors of about 2or 3 Megohms and C21 (in the Mkl

or C23 in the Mk2 or MkB) isshunted with an additional capacitorof about 1(X) or 200nF and the con-trols are reset.

Reduction in receive gainwhen operating mobile with lowbattery voltage FT101 Mkl. This iscaused by the voltage on the low -frequency IF unit varying. To curethis defect, operate the FT101 from amains supply, tune in to the crystalcalibrator, and note the S -meterreading. Disconnect the unit fromthe mains and connect an 11 -voltZener diode in parallel with C36(this will be found at the top left-hand corner of the circuit on page15 of FT101 Mkt manual. When theZener diode has been fitted, connectthe unit to the mains and note thatthe S -meter reading will have fallen.The gain can now be brought to nor-mal by adjusting the value of R15 inthe base bias circuit of Q2. Usuallyabout 4.3k is correct, but the exactvalue will depend on thecharacteristics of the transistors.Once this modification has beencarried out, the gain of the receiverwill be much less affected by varia-tion of battery voltage.

RF gain onlyone third of rotation. This effect iscommon and many hams haveordered new RF gain potentiometersonly to find that no improvement en-sues. The problem is one of com-patibility between the RF/FET/Q1on the RF board and the IC andtransistor fitted in the IF amplifier. Ifthe effect worries you try a few dif-ferent 40673s or 3N2O1s asreplacements for Ql;

No signals on receive butcrystal calibrator at normalstrength - FT101 Mk2 FTIOIE.This fault indicates a blown aerialprotection lamp. This is mountedunder a plastic cover adjacent to theaerial socket. A pilot lamp can beused as an emergency replacementhere.

Intermittent non -operation offan and transmit function on DCsupply particularly when coldFT101 Mk2E. This is caused by thechopper/inverter transistors refus-ing to oscillate due to lack of gain.The cheap cure is to reduce thevalue of R3 to about 100 ohms.


Faulty heater switch. Intermit-tent operation of the heater supply isusually due to high resistance con-tacts on the heater switch. Thisswitch is a double pole type, onepole for switching the sidetoneoscillator on and off, the other poleswitching the heater supply. Aquick cure here is to clean theswitch and swop the wires over asthe slightly faulty contacts willusually handle the sidetoneoscillator, and the original sidetonecontacts will be as good as new.

Plugging phones in does notcut out speaker. This is usuallycaused by the use of the wrong typeof jack plug. Stereo jack plugs or'Post Office' types with small tips arenot suitable, round tipped monoplugs being the order of the day. Ifthis does not cure the trouble notethat quite a few FT101's seem tohave escaped with the phone jacksocket wrongly wired, so if the inter-nal speaker still does not cut out,consult Fig. 4 and rewire if

necessary.

Plenty of PA current but poorPA dip and RF output low. Thecauses of this effect can be manyand have included a faulty 600Vfeed choke, faulty pi -tank couplingcapacitor, or a blob of solder on thePA coil.

Oscillation or distortion asmike gain advanced at some fre-quencies on the 160m band. Thetrouble here is that the RF choke onthe patch input socket is resonant.This can either be disconnected en-tirely if the socket is not used, or thechoke can be replaced by one with aferrite core. This fault seems to

mainly occur on FT101B's, and pro-bably later units are already fittedwith a different choke.

Workshop manual. A verygood operating and maintenancemanual is supplied with the FT101.These notes - whilst it is hoped theywill be of general interest -presume that this is available.Owners wishing to delve further intotheir rigs might like to know that afull workshop manual is alsoavailable via Yaesu dealers.

Safety. The on/cff switch is asingle pole type and does not isolatethe FT101 from the mains supply.You must therefore remove themains plug from the wall socketbefore attempting service work. TheFT101 contains large capacitors andhigh voltages. Some points such asthe top caps of the power amplifiervalves remain live at 700V for some

considerable time after the set hasbeen switched off. Never touch anypoint in the PA cage without firstshorting the top caps of the PAvalves to chassis (leave the rig tostand for 1 minute after disconnec-ting mains supply before doing this,or use a resistor of a few hundredohms to avoid an excessivedischarge current.)

Fuses. The fuse should be a 3amp quick blow type for use on220/240 volt supplies.

Swopping the pilot lamps.Several owners have damaged theirFT101 by causing a short circuitwhen replacing the pilot lamps.These are run from the rectified DCsupply, and a short circuit will burnout the rectifiers in the power supp-ly. Do not try and swop them whenthe rig is switched on, or fit themwrongly so that the wire shorts to thechassis. Equipment which has beenimported by the approved importeris normally stamped on the rear"234V". Many unofficial imports,and some Sommerkamp equipmentis set on 220V and should be re-wired as per the instructions in themanual. Operation at UK mainsvoltages on the 220 volt setting willconsiderably reduce the life of com-ponents in the FT101.

Valves. The FT101 is designedto function with Japanese valves andNEC or Toshiba are recommendedby Yaesu. Some other brands willgive poor results, refuse toneutralise, or even oscillate in thereceive mode and cause damage.

Fig. 4 rear view of headphone jack socket


Test generator. Pull the aerialout of the FT101, switch on thecrystal calibrator and note the max-imum reading which can be obtain-ed with the pre -selector peaked,and set tuned to 14.2MHz. Thisshould normally be between S9 andS9+ 20dB. Keep a note of thisreading as it will be a most valuableguide when later making com-parisons if there is any doubt as towhether or not the receiver is up toscratch.

Field effect transistors. TheFT101 contains a fair quantity offield effect transistors which canvery easily be damaged by heat orvoltage. Plugging the FT101 into themains supply - whether switchedon or not - will usually guarantee apotential difference between the tipof your soldering iron and the cir-cuitry. Touch the soldering iron oncertain points and the nearest FEThas gone for the chop! Your only safeway to solder on the FT101 is to com-pletely detatch it from the mains,aerial, earth, and any other equip-ment, and then to use an iron whichis earthed to the chassis of theFT101. Familiarity with the normal

bipolar transistors can lead one tobecome careless, but heat shuntsreally are essential when solderingFETs. A piece of cotton wool soakedin water provides ideal heat andstatic protection if stuffed betweenthe four legs of MOSFETs whensoldering. An elastic band and apair of snipe nosed pliers provide athird hand and a heat shunt whenworking on the three legged varietyof FET.

Harry Leeming asks us to pointout that while he is happy to answerbrief queries on the FT101 series,correspondence must contain astamped, addressed envelope to ob-tain a reply.Harry Leeming will be coveringmodifications in future articles.

Alignment and fitting 10, 18 Si 24MHz will be covered, together withAGC and modifications and otherreceiver and transmitter im-provements. But what about you?

Bright ideas' and servicing ex-periences should be shared aroundso let us know what you have donewith your FT101 - please type (orprint CLEARLY) and send your con-tributions to the editor for possibleinclusion in part 4 of the series. Thebest contribution will receive 12months' subscription to Ham RadioToday.

NB In our April issue (p.21) theparagraph beginning "1976 FT101Mark 2" should have been "1976FT101E Mark 2".

FORTOP LTD, FIRST AND BESTFOR FAST SCAN TV.

.0 FilliiO4. Lii

r11436

The TVT 435/R TV transceiver allows transmission and recep-tion of 70cms Amateur TV signals. Features: IS watts mm PeakSynch RF output. Bandwidth limiting filter, switchable modulationsense, video inputs and carrier frequencies. High performanceRX converter built in. Requires aerial. 12 volts power, videosource (camera etc) and stand UHF TV set to complete fast scanAmateur TV station £169.50 plus £2.50 P&P.

For further details please write or ring to:FORTOP LTD, 13 Cotehill Road, Warrington, Stoke on Trent, tel

Ash Bank (078 130) 2607

GET BINDINGTake a subscription out for £12.80, and getyourself a FREE binder worth £4.25 to keepyour favourite magazine in mint condition.

Back issues of Ham Radio Today are availableat £1.25 per isue. Send your cheque/PO to:

Ham Radio Today513 London RoadThornton HeathSurrey CR4 6AR

THE CW/RTTY COMMUNICATIONS TERMINAL

miurru

MOP

£381.74 inc. carriageStandard unit cost - VAT not included)

Forget all those messy wires, theMICRODOT now offers a totallyintegrated communications system.

Write for full details to . . .

POLEMARK LtdLower Gower RoadRoyston, Herts SG8 5EATel. Royston (0763) 47874

STANDARD FEATURES INCLUDE Integral high resolution video monitor Professional keyboard with many special functions Real-time clock (constantly displayed) Transmit and receive both CW (morsel and RTTY

(teleprinter)Users callsign programmed in

Receive CW speed tracking and displaySelf checking facility

Char. by char. or 'page' transmission modes Stylish two tone metal cabinet

OPTIONAL FEATURESPrinter interface board (Centronics compatible)

On -board 40 column printer (12V) External 80 column printer (SEIKOSHA GP100A)


G Line for theGigahertz Men

By A dy Emme on G8PTH

Ask your friends at the local clubwhat G -line or G-string is and you'llprobably get a bemused grin follow-ed by a blank stare. Yet G -line(named after its 'inventor' Gobau) isa remarkable form of RF feederwhich uses a single wire fortransmission. What's more, it offersvery low loss at UHF, comparablewith the best hardline feeder. For allthis, G -line has never found muchfavour and this article is an attemptto clear away some of the mysterysurrounding Gobau's brainchild.

Finding information on G -line isnot an easy task. My first encounterwith it was in the October 1965 issueof Practical Television, which con-tained a description of the amateurTV station G6CTS/T located at Nor-wood Technical College, south Lon-don. This station was conceivedback in 1947 by the EngineeringGroup Royal TelevisionSociety as an experimental stationfor UHF TV. A few years later itwent on the air (vision frequncy was

,427 MHz - those were the days of a70cm band 30MHz wide!), and pro-vided test transmissions with visionand sound for the London area. Twostudents at the college were involv-ed with a research project relatingto the transmission characteristics ofsurface wave feeders. This surfacewave feeder was G -line, andphotographs accompanying the arti-cle showed the G -line feeding the70cm aerials and some strange look-ing cones. No further details weregiven, and it took me a while to trackdown more information.

An article by K6LK in the June1974 issue of QST (the USAequivalent of Radcom) and somenotes in microwave textbooks subse-quently supplied the missing data,and fact turned out to be strangerthan fiction. A bare metal wire mayact as a waveguide for propagatingelectromagnetic waves, with lossessmaller than most grades of coaxialcable. Virtually no radiation occursfrom the wire and well-nigh all theenergy is carried in a circular fieldclose to the wire. Cone shaped laun-

ching and receiving devices are us-ed to match the G -line to conven-tional coaxial feeder, with the resultthat G -line can be used for longruns, reserving the use of coax forthe more complex connections atthe transceiver and aerial ends.

No doubt this sounds likescience fiction to some readers andwhile it is not, it must be admittedthat there are some snags whichrestrict the utility of G -line. The linemust be kept fairly straight, other-wise radiation will be lost at bends.G -line must be kept clear of metallicobjects and standing waves are aserious problem. Nonetheless,workers who persevered have hadsuccess with G -line and after I havedisposed of the theory I'll give somepractical dimensions and details.Gobau, who popularised G -line,showed that for a bare copper wireof 2mm diameter stretched in airand excited at 3000MHz the attenua-tion was a mere 0.023dB per metre,and the extent of the field was suchthat 75 per cent of the transmitted

energy was conveyed within a circle36cm in diameter around the wire.A demonstration system is shown inFig. 1. The inner conductor of thecoax is joined to the G -line while theouter conductor is soldered to thelaunching horn. The angle of flaremust be kept small to keepundesired transmission modes to aminimum. Calculated results aregiven in Fig. 2 and in experimentsthe measured total loss has com-pared well with the calculatedvalues.

George Hatherell, K6LK, madehis experiments at 1296MHz with anumber of types of wire. An accep-table compromise was with a 100 ftlength of 14 SWG wire, which gavethe following results:Enamel coated wire . . loss 3.87dBDitto sleeved with Teflon loss 2, 53dBPlastic insulated household

wire (white) loss 3.62dBDitto (black) loss 3.87dB

Transmitted power was 10 watts.While these results were encourag-ing, subsequent 'souping up' of the

COAXIALCABLE

HORN

120 ft

ENAMELLED COPPER WIRE0.2 cm

Fig. 1 Experimental surface -wave transmission systemHORN

2

dielectric

1000

Ow -

2000 3000 4000 5000

Mc

Fig. 2 Transmission losses forthe 120 -foot surface -wave guideshown in Fig. 1

system brought the total loss of theG -line and launchers and receiversto well under 2dB. His article givesall the constructional details of thelaunching and collecting horns andhis method of suspending the G -linefrom tightly stretched monofilamentfishing line.

REFERENCESHatherell, QST, June 1974, pp11-15, 152, 154.Gobau, Proceedings of the IRE, 39,pp 619-624 (1951)

Journal of Applied Physics,21, pp 1119-1128 (1950).


* 30MHz down to 150kHz (and below).* 12 Channel memory option with fine tune.* SSB ILSB/USBI, CW. AM, FM* 2.7kHz, 6kHz, 12kHz, 15kHz, @ -6dB.* 3 Selectivities on AM. Squelch on FM.* Up conversion. 48MHz first IF.* 1kHz digital, plus analogue, display.* Inbuilt quartz clodUtimer.* No preselector, auto selected LPF's.* Advanced noise blanker fitted.* Antenna 500 ohms to 1.5MHz. 50 ohms to 30MHz.* 20dB pad plus continuous attenuator.* Switchable A.G.C. Variable tone.

'7700 THE ONE WITH FM!NON -MEMORY VERSION £335

COMMUNICATION RECEIVER:30MHz to 100 KHz or lower, 100Hz stepsPLL digital VFO, outstanding (50Hz AWU) stabilityBacklash free, 10KHz rev, 500Hz analogue calib.Fast tuno up/down switch, dial lockout.SSB (USB/L.SBI, CW, AM, RTTY.6 and 2.4KHz, 600' and 300' Hz @-6dB.Passband tuning ± 2KHz on SSB and CW.Variable BFO on CW for preferred tone.Modular plug in design with mother boar.High reliability - low power schottky & CMOS.Designed for maximum ease of operation.Noise blanker 0-10-20dB attenuator.Small (140 a 340 x 300mm) light 7; Kg, rugged.Up conversion, 70.455 MHz and 455 KHz.

PROFESSIONAL MONITOR

FT726R MULTIMODE VAT @ 15%TRANSCEIVER £6489 inc. &SECURICOR

MULTI -BAND VHF/UHF'Option

* 2M. 1 2VDC compact 2 2/16" x 6'a" x 7 3/16" transceiver.* 25W I+ adjustable low power). 12'-, kHz steps.* 10 "year long" ememones for "crystal control".* Display reads 100's of Hz or channel number.* Sensitivity < 0.2uV for 1 2dB SINAD (0.14uV typical).* Single knob frequency selection. 20 steps revolution.* Rapid OSY button, end to end in a single turn.* Digital RIT 1 kHz steps. adjusted from main tuning.* 2, 5 slot memories, simplex, cross or 600kHz split.* Memories entered by pushing main tuning knob.* 600kHz split. Instant repeater input monitor.* Band scan between font panel selectable, limits.* Scan stop requires squelch open and centre zero.* Scanning and up/down tuning on the microphones.* Reprogrammable, Steps. tone, splits. and coverage.* C/W mic. "Easy out" mobile mount end handbook

- -... .... ....v.v....!... ...... ...... "'S. .......

...-......- -- --- --- ---;:-. ----

\ \ \ \ i 1 / ).... -- ''/..,.\. -----..- - --- ---_,---z---- - --- -.....---

South MidlandsSMC YOUR SINGLE STOP SOURCE FOR RECEIVERS,

RECEIVER WITH 12 MEMORIES: FRG7700M £399 inc. VAT 15%& SECURICOR

* 110 and 240Vac. 12Vdc option.* Signal meter calibrated in "S" and SIMPO.* Acc: Tuners, Converters, LPF, Memory.* FRT7700; 150kHz-30MFiz, Switch, etc.* FRV7700A; 118-130, 130-140, 140-150MHz.* FRV77008; 118-130, 140-150, 50-59MHz.* FRV7700C; 140-150, 150-160, 160-170MHz* FRV77000; 118-130, 140-150, 70-80MHz.* FRV7700E; 118-130, 140-150, 150-160MHz* FRV7700F; 118-130, 150-160, 170-180MHz.* FF5; 500KHz (for improved VLF reception).* MEMGR7700; 12 Channels (internal fining).* FRA7700; Active Antenna.

VAT 5%NRD515 £985 inc. & SEC U1RICOR

* No R.F. amplifier balance U310 mixer.* Crystal filter before first IF amplifier.* Transceiver provision: VFO !trout. sidetone. mute.,trip etc.* Frequency data input/output port.

NHD518 96 14 a 24) channel memory unitNCM515 Remote keypad controller. LCD readout.

Up/down step tuning. 4 channel memoryCOE515 Junction unit INCM515 to NHD518)NVA515 External 3W speaker 130 x 140 200mmCFL260 600Hz mechanical filterCFL230 300Hz crystal filter

* 3 Bendel 2 metres. 70cms (10MHz) & 6M' plug -ins.* Full Duplex'! Cross band Tx & Rx simultaneously.* SSB-CW-FM! All optimumly catered for.* Variable bandwidth and IF shift! SSB & ON.* Processor! Front panel mic gain and drive.* Two main VFO's! A & B with 20Hz steps.* Separate channelised VFO! (for FM operation).* Scanning' Over the band, 10 memories. between memory limits* Repeater splits' programmable and preset.* Instant reverse' and a & - splits and A/B.* Twin meters; PO/DISC, S/ALC. Duplex switchable.* Switchable; AGC, CW bandwidth, dial lock.* Noise blanker; impulse interference tuned. 'option.FT726R(2) Transceiver c/w 144 MHz f649.004301726 430-440MHz module £208.90501726 Six meter module £157.15SAT726 Full duplex unit £82.80

MAIL ORDER; AS NEAR AS YOUR 'PHONE OR PENSMC SERVICE

Free Securicor delivery on major equipment.Access and Barclaycard over the phone.Biggest branch agent and dealer network.Securicor 'B' Service contract at £4.49.Biggest stockist of amateur equipment.

FREE FINANCEOn many regular priced items SMC offersFree Finance (on invoice over £100).20% down and the balance over 6 months or50% down and the balance over a year.You pay no more Man the cash price"

GUARANTEEImporter warranty on Yaesu Musen products.Ably staffed and equipped Service Department.Daily contact with yaesu Musen factory.Tens of thousands of spares and test equipment.Twenty-four years of professional experience.

S.M. HOUSE, RUMBRIDGE STREET, TOTTON, SOUTHAMPTON, SO44DP, ENGLAND.Tel: Totton (0703) 867333, Telex: 477351 SMCOMM G, Telegram: "Aerial" Southampton


Communications Ltd. '(I,\\\\TRANSCEIVERS, ANTENNAS, TOWERS, MASTS, CABLES, ETC.

- =.- .."

'ii)

* 80.10 metres including WARC allocations* Multimode LSB-USB-CW (W)-CW (N1' and FM* 100W PEP output. (10W "S" version).* No tune design - inbuilt SWR meter.* Only VA" x 91/2" - Less than a foot deep!* Dual selectable pulse width noise blanker.FT77 Transceiver 100W outputFT77S Transceiver 10W outputMARK 7 Crystal Marker boardFMU77 FM UnitXF8.9HC(N) 600Hz or 300Hz (N)FV707DM Digital Memory VFOFC707 Antenna TunerFP707 Mains P.S.U.FTV707 Transvertor. frame only

Modules:

£475.00£399.00

£7.65£23.75£24.90

£203.15£85.10

£112.50£90.00

432 £185, 144 . £100, 70 £80.00 ALL BAND MULTIMODE

v FT77 MOBILE RECEIVER£475 inc. VAT 15"

& SECURICOR

160-10 metres including new allocations.Variable IF bandwidth 2.4kHz down to 300Hz.Audio Peak and independent notch controls.AM, FSK, USB, LSB, CW, FM, (Tx and Rx).'Semi -break in, inbuilt Curtis IC Keyer included.Digital plus analogue frequency displays.VOX built-in and adjustable.Instant write in memory channel.Tune up button 110 sec, of full power).Switchable AGC and RF attenuator.Optional 350 or 600Hz CW, 6kHz AM filters included.Clarifier (RIT) switchable on Tx, Rx or both.Plug in modular, computer style constructor.Fully adjustable RF Speech processor.Ergonomically designed with necessary LEDS.Incredible range of matching accessories.Universal power supply 110-234V AC and 12V DC.'

0110\--c°'"osc),"c\s

*.svt\o\-\c,\.\30

4!'FT902DM BASE STATION

£885 inc. VAT @ 15%& SECURICOR

D & DE MODELS AVAILABLE

4 FT102 £785 inc. & SECURICORVAT @ 15% * 1.8-3.5-7-10-14-18-21-24.5.28MHZ

* All modes:- LSB. USB. CW, AM t. FM i (f Option board)* Front end: extra high level, operates on 24V DC.* RF stage bypassable boosts dynamic range over 100 dB!* Variable bandwidth 2.7KHz - 500HZ and IF Shift.* Fixed bandwidth filters. parallel or cascade configurations.* IF notch (455KHz) and independent audio peak.* Noise blanker adjustable for pulse width, (Woodpecker).* External Rx and separate Rx antenna provisions.* Three 61468 in special configuration - 40 dB IMO!* Extra product detector for checking Tx IF signal.* Dual meter. peak hold ALC system.* Mic amp with tunable audio network.* SP102:- Speaker, Hi and Lo AF filters, 12 responses!* FV102:- VFO. 10Hz steps and readout. scanning, OSY.* FC102:- ATU. 1.2KW, 20/200/1200 W FSD PEP, wire.* FAS-1-4R:- 4 way remote waterproof antenna selector.

FT980 £1115 inc. &vstrcilRiaR* Rx 150kHz-30MHz.* Tx 160-10m, 9 bands x 3 x 500kHz Aux bands.* All modes AM. CW, LSB, USB, AFSK & FM (inc.)* IF shift & variable bandwidth 2.6kHz-300Hz.* Inbuilt keyboard operation + scanning.* Switchable attenuator 10.20. 30dB.* Audio peak + notch filter - 40d8* RF processor and Auto mic gain control.* 3rd order IMD - 40dB at 100W PEP.* AFSK shift 170. 425, 850Hz selectable.* Multi channel memory + programmable scan limits.* Optional computer interface available.* Notch filter in IF (AGC immune to hetrodynes).* Full break in keying. 500/600/700Hz beat.* Unique analogue scale of digital type.* Comprehensive twin meter metering.* Memory retains mode information.

SHOWROOMS: SPANNING THE UK-TO SERVE YOUSOUTHAMPTON LEEDS CHESTERFIELD BUCKLEY STOKE GRIMSBY JERSEYSMC Ltd SMC (Leeds) SMC (Jack Twendyl Ltd SMC (7MP) SMC (Stoke) SMC (Grimsby) SMC (Jersey)36-38 Rumbridge Street 257 Otley Road 102 High Street Unit 27. Pinfold Lane 76 High Street 247A Freemen Street 1 Belmont GardensTotton, Southampton Leeds 16. Yorkshire New Whittington, Chesterfield Buckley, Clwyd Talke Pits, Stoke Grimsby. Linos St. Helier, JerseySouthampton (0703) 867333 Leeds (0532)782326 Chesterfield (0246) 453340 Buckley (0244) 549563 Kidsgrove (07816) 72644 Grimsby (0472) 59388 Jersey (0534) 77067-5.30 Mon -Sat 9-5.30 Mon -Sat 9-5 Tues-Sat 9,30-5.30 Tues-Sat 9-5.30 Tues-Sat 9.30-5.30 Mon -Sat 10.7 Mon -Sat

SMC STOCK CARRYING AGENTS WITH DEMONSTRATION FACILITIESEdinburgh Jack GM8GEC (031-857) 2430 Day

1031-665) 2420 EveBangor JohnTandragee Mervyn

G13KDR (0247) 55162 Heath John GW4F01 (0639) 52374 DayG13WWY (0782) 840656 (0639) 2942 Eve


Tel: -G2Ii7v7 - 6e2u2sa4r;:g0 or219435

YAESUFT 77 New ni,delFT 700 New modelFT 726 New modelFT 980 New modelFT 730 New modelFC 102 ATUSP 102 SpeakerFT 102 160 10M 9 Band TransceiverFT ONE Gen Coverage TransceiverFT 790R 70cm all mode portableFT 101ZDFM 160 10m 9 Band TransceiverDCT 1012 DC AdaptorFV 101Z Remote vfoFV 10IDMFT 902DMFC 902FTV 901R430 TV144 TV70 TVFV 9010MSP 901FL 2100ZFT 107DMSFT 707FP 707FC 707MMB 2FRG 7700MEM 7700FRV 7700AFRV 77008FRV 7700CFRV 7700DFRV 7700EFRV 7700F

FRT 7700FT 480RFP 80AFP 80AFT 780RFT 2908NC 11CMMB I i

FT 208RNC 9CFT 708RFT 2308

9 Band AM FM Transceiver9 Band atu, swr pwr etcTransverter fitted 2m module70cm module for above701 module for Transverter4m module for TransverterRemote vfo for 901External speaker9 Band 1200W linearwith memory Et FP 1078 -Band solid state 100W230 volts AC power supplyAerial tunerMobile mounting bracketSSB AM FM recvrMemory unit for above118 150 MHz Converter50 60MHz Es 118 150MHz140 170MHz70 80MHz & 118 150MHz140 160MHz b 118 130MHz150 160MHz, 118 130MHz Et170 180MHzReceiver aerial tuner21, all mode transceiver230V AC power supply230V AC power supply70, all mode UK rpt shift2. .01 mode portableAC chargerMobile mounting bracket2in synthesized portable FMAC charger70i ill hand held2ni FM mobile

0515.00P.O.A.699.00

1215 00299.00225.0049.00

839 001450.00

349 00599 0042.50

112.00249 00895.00135.00285.00185.00100.0080.00

260 0031.00

485.00699.00509.00112 5085.0016 00

299.0089.0069.7575.5065 9572.4571 30

All Yaesu Ws available mostly ex stock

TRIO-KENWOODTR 7930 2iir XCVRR 2000 Ri..TR 3500 gh ii HandyTS 930 ovilageTS 830S 160 10in transceiver 9 bandsAT 230 All bang ATU power meterTR 2500 2iii F M synthes ed handheldDM 801 Dip meterR 600 Gen , oOverage receiverAll Trio Ken aik essories available

TS 280FMFT 78FT 277ZDFT 902DM

SOMMERKAMP2in Mobile 50W FMHF Ild115C1.11/1.1HF Transceiver FMHF Transceiver FM AM SSB

71 3037 85

365 0063 0063 00

449 00285 00

80022 25

199 00800

209 00255 00

NEW P 0 ANEW P 0 ANEW P.O.A

1155 00650 00110 00207.0060.00

199,00

ROTATORSKR 250 Kernpro Lightweight 1 1'; mast9502B Colorator IMed VHF IKR 400RC KenproKR 600RC Kenpro

199 00399 00710 00885 00

44 9555 0099.95

139 95

ICOMIC 740 Multimode H F traitscerver 769 00IC 720A HF transceiver and gen coy rec 799 00IC 730 HF mobile transceiver 8 band 586 00ICR 70 Multimode receiver NEW 469.00PS 15 Power supply for 720A 99.00IC 251E 2m multimode base station 499 00IC 25E 2m synth compact 25W mobile 259.00

-ARROW7 Coptfold Road, Brentwood, Essex CM14 4BNTel: 0277 226470 or 219435 Ansafone on 219435 Telex: 995801 (REF: A5(

C 290E 2m multimode mobile 433.00 ALINCOC 2E 2m FM synthesised handheld 1 79.00 AL 230 2n 30W Linear 1 3W inn FT 2908C 4E 70cm handheld 199 00 etc 39.00CL1 :2 /3 Soft cases 350 AL 710 70cm lOW Linear 65.00C HM9 Speaker microphone 12 00 AL 730 70cm 30W Linear 79 00Car chargingead 3.20C BP2 6V Nicad pack for IC 2E 22.00 SAGANTC BP3 9V Nicad pack for IC 2E 17 70 MT 240X HF 80 10m Win array 49 50C BP4 Empty case for 6 X AA Nrcads 580 MTE 40X 80m 40m array 45 00C 8PS 11 5V Nicad pack for IC 2E 30 50 BL 40X 1 1 Salon SO 239 13.80C DC1 12V adaptor pack for IC 2E 8.40

TRIO FRITZELLCI 303G Communication scope 170 00 D 4 Windom Arras HF bands 31 50PF 810 Power SWR meter 85.00 FB 16 1 6 Baluit for DIY 17 45Catalogue of Trio instruments send SAE Send for details NEW RANGE

TONNA HALBAR2011 7 2m 17 element 35 19 LIN 5 70c,,,5 el y,ig, 79920505 50MHz 5 ele 31.74 ST R 5 2in 5 el Vag. 99920104 2rn 4 ele 12.99 FOLDI 21115 el Foldop 13 0020109 2rn 9 ele 15.44 TWIN 2111 Vert 14 9520209 2m 9 ele port 17.46 TWIN 70 70cth Vertitai 7 9920118 2m 2 9 el cross 28.51 DIP 2 211, Dipole 39520113 2rtl 13 el port 27.20 HALO 211, Halo 55020116 2m 16 el 29 95 L PA Log periods /0, it 15 0020419 70cm 19 el 18.12 QUAD 6 2,116 el Omni 25 0020438 70cm 2 9 el cross 30 05 QUAD 4 2114 el Otiati 17 5020421 70cm 21 el 25.9820422 21 el. ATV 25 9820199 2m 70 Oscar 30 05 DAIWAFull range of Tonna accessories stocked DR 7500X rib Ili 3 I tit his.. ;al..,

98 00

G -WHIP MOBILE ANTENNA RANGE DR 75008 107 95DR 7600X 141 00Tribander helical for 10 15 20 rneteres 25 80 DR 7600R .s abi bt . ii 152 00Base mount single hole fixing 3m cable 6.30 KSO 65 Stin, 18 50coil for above aerial 6.55 CS 201 2 Was .vvitt 11 98LE 80m coil for above aerial 655 CS 2011. abovrA N .et. 19 00LF 160w coil for above aerial 6.55 CS 401 4 was A SO 239 34 95LF telescopic resonator whip 4.25 HM 947 infra Rest 1111. 45 00We also stock flexiwhip Et multirnobile G whips Ch 527 I 60MH, SC. R 32 50crx 540 50 150MHz SWR 35 00

WELZ RX 110L+ 2m 6.9S NEW 39 00RX 430G 10, n (;..S NEW 63 00SP 10X Mini meter 1 8 160MHz 200W 19.95 RE 677 RE h NEW 44 00SP 15M 1 8 150MHz 2 5W 200W 29.95 D 301S . AP, . Fill. 11 50SP 45M 2n 70cni 100W 45.00 0 30M t P Faun HD 19 50SP 200 8 160MHz 20W 200W IkW 59.95 PS300 Variable PSU 135.00SP 300 8 500MHz 20W 200W I kW 79.95

SP 350 8 500MHz 200W 49.95 MISCELLANEOUSSP 400 30 500MHz 5W 20W 150W 59.95 14 95SP 250 6 60MHz 2kW 45,00 ARRO,.*. All! ii11./ 82 00SP 380 8 500MHz 20W 200W 49 95.PS.

;OA X I., I 'ION I d$1,1111S1AC 38M 8 band ATU 59,00 Aran., 20p lootCH 20A 450MHz coax switch 15 95 SWEDISH KEN Ifltly, 1..ik o .1 il/ 49 00CT 150 150 400W D load 31 00 EX ,.r .nu. I, nes kiik k 64MHzCT 300 300 IkW 250MHzO load 43 00 ,o, 80 00

TONO NI NPR() KP Ill. K.... 69 00

THETA 9000E R1 TY CVVASC1 1 650 00THETA 550 The latest a winner 299 00

TETTASCO 33S,' go, H. MI' 189 00

TeieReadei CWR 685 RT TY CW ASC 1 I 699.00 `.IL 38 40 25TeleReader CWR 670E As above RX only 259.00 514, 71 25MorseMaster CWR 600 As above basic unit 189 00 st) 118 1 48 96

CARRIAGE b VATPRICES L uOt VA I t Ms 0018 ISO 00 VALUE

ADONIS MICROPHONES .)R 101AL ORDERS OVER lab ARE CARRIAGE FREEMM 2025 Soleilit IVUe 20.95 St CURICOR OUR OPTION lUH MAJOR ITEMS ALLMM 202HD Safety 1111C head band 29 00 lESPAICHES ARE NSUHED 111. S NO RISKS TO YOUMM 202HM Headphone b mac 39.00 , OS! OR !)AMA,,ED

NEW INCT1000 Com-puter ControlledRotatorFT77 New YaesuMintFT980 Stock nowIn

SP980 Speakerfor FT One/980

PHONE YOUR ORDER FOR TODAY'S DESPATCH ALL WE NEED ISYOURkl.Pr1.7 OR i NUMBERSMALLSPARES PLUGS AERIALSPHONE FOR A QUOTE FOR THATNEW RIG,

OPEN 5 DAYS A WEEK CLOSED THURSDAYS


../3 MI

08

L,34 (PB-1515 AF UNIT) MJ (4)249101 OF-MIC AMP 02 MIC AMP 03-E --,F 04 --N/FiX AMP-

rj/9-r-cN) i 2tSKI9GR 2SC372Y 2SC372Y TA -7042M(2SC828P) (2SC828P)

RS or

41,

Hi -41 "r

,x2 ERNI":1

NOTES

I AI L RESISTORS ARE IN I/4W

UNLESS OTHERWISE NOTED.

2. ALL CAPACITORS ARE IN u FUNLESS OTHRWISE NOTED.

3 ALL ELECTROLYTIC CAPACITORARE I6WVUNLESS OTHRWISE NOTED.

4 X VALUE IS NOMINAL.

FT-10IE1 CIRCUIT DIAGRAM

C.4 R.

9 Co4.7K

J"I 4a470F /N1S-1T

C220.0/

12,t+.04 /S/555

IC

08 AN -214

BUFFV 0SC __ SU

Cib I 2SKI9GR 02 2SKI9GR (2SC 8P)D

Ic.

c., .4 zzkr II

4.'ili CiliP13 44 Cir.A

)4VI'

III /0K

05 RELAY CC2SKI9Y

2SC

SP!SP

.T11

GINO

5 RELAY CONT.2SKI9Y

a

4

re

fir Or

062SC373

J.7^Rae 2:2K

-

00

4c sop eta

.e.,---tirlil104(.,slitirttomiL-ka-40

- L 7caa

-4 L'

VS0/ , -.6 Llamas%

0 0"\---- ig' .I os Ds ..C-___> I F

.4,r ,p4 4i012SKI9 Y'.77,4), Ir. _t

I ,,,, ea01410 IA/It Vs4 1I.tl- joAct

1 1

1 k PT Z.;

fe"Wo 01-04 /8407

MJ (5)st 121.1*4.AMQD ILOS_C ITL.R

Z5504 2SC828P BUFF 5.

I>C414

0.1.C.18,7.

ti

I-6

f4 71

/4 RUK

AM I MOD/CW BUFF02 2SC372Y(2SC828P)

c3421.3op

06 2SC372YAM/CW

;"

xtr:4") 2141

. '=1at 8i; 408i nriir

5P1 t 4n

aP,,

L8 215250/W

I032SC372Yuse

N

777

is

40457

05 2SC372YLS8 .;4$

II

14

273:872

CI

rrI F

?Pr

01 2SKI9GR

Xi.3,86

;43Lt ^L4

asztoot

L

AGC04 25C8280

lOOK /ow 06 05

052503280

%k ad

RN,,,,e4

U.4431

711

Ref) 47

*-1C333r11-103249/ 40/

870IC

0ILEL/47.._1

vh# VR3b

0--

O

a

-49°

s z a

/5/555

itiaMA

n

4:

iTLR-104

PLS

4

ev a

825 777"

32406

5 0

414!142,

(P8-1292 N B UNIT) -02 2SKI9GR 01 2SC372Y

H-

rr1 F

01 2SKI 9GR

R 701.1

Yr-//6

C936P

LS HRH -rtD3

/S/556

10.7C42 AT/047CP"

1 F

02 2SC784R

00I 470P

zr-azAXF -I

3100KHZ

As, D7-am hsm07 03 CA 3 53

VR36 10K841

r -e19

LEVEL CON 7-

-o -P8 -153 4

FIX 8.1 RF PROCESSERUNIT

I Sit rio 1

I o's /S/5.55 I

I I

RIO ZZK Hi 1

11.!4, 3

012 -0-40-#6-

MJ (2) MJ (I)(F 8-1180B P8-10828 MIXER UNIT / P8-1166 ( P13-118113 F_

0 I 2SC372Y R.5. , 03 2SC784, FA TRANS 2nd I

CZ 477P

01 D9 ISI5S6

VR2

a,

ri: Ri4 03 4.

54d

REGULATE

04 MFC6034A

CH /00P

7,7

02 2S1

o R9

C7A

R

tLOCAL RSC

6ItC372Y'

1219 470'"

VR4 Ike 1

4

41

Cl3.1 3P C 2 470

MJ (I)VIT/PB1166 (PB-118113 RF UNIT)

k 1-0,E2a784RTRANS 2nd MIXC// loop

I'>_2_141I

'o.

0f;7.)

g4,

rra

fa.s9

TT:

0

) esfz

L.- _LOCAL OSC

Q2 2SKI9GR

4n11

ce:

C9 4O'

k oVICt.."/_i t2,41_.

1 2wtHcl. Re 1)15--- RF22K

0 I4.,

1:

3SK40

40`4,

A t 47

.1 m/AO& r 01

E.F2SC373

.1,710

ii-

M

-v

I11#1:i 1.3

W1V

4-009

Volo.j,1105 led ,

r1.

Si'

A3..4

.4

VI I BY7ArorDRIVEJ.,

0. , L

fez 3.J K 7/2W SI e r ----

es.ro,rc SOP -'-rcs /op IC, TNrem 4a7P - -

P13 -1187A ,Z 1/4)

C.AO7SHOP /

it Si,

ir Akiu AID

Wll1+0 rCe.

re7-7L1rCA9 420P PB-I092

as/ VOX'

rJr

V2 V3 PA6JS6Cx2

7T27Nefr 0/55

AXIP IAIVV

gSKVAr g

44

Fad09I 6cvav

It.4

-4 It

V 40O

250,44 II Ii4

8401.5%SW

,J

N

F-1

P

n 02131555

4.)

/-C4,r /

v2 V3 / %

,\c,/;C73#1,

to.

0

[SC372

RPPRIP0 00

144=3 r..o %2'&'.g Vs

1013

I S/s,

in,

.1

' 7., PA/A

2

(PB-11B8 RF TRIMMER), 7i4 I

L_1

o kI

1%

,:. 1

itl .i ' f

i_

Sib

rC/I, TC is SOP (MAX)

?vasrc29

142oP(M.0)

7-' zekbi asA

L-/56)7A

r_LA4

Sid Sic

t

1

j I I

-F-

1/4

_

331E

7- - C..

as

ts133,5Dt3

'IMO

i: 54Z " f .:.4 Elle 4

0 ../.....4/ 4)

O t

0 0 0 CD 0tit a°

MR,9 470

XIvc,//ev *off CSer

kr WI

SAP

6=i;4

PLZ/6 V SWAN

251412 MULTIQ2 MFC6020

c? 'roe

[rfa/J 49

6.0C1 at1-4-0-

1.&

4-40

I

_ _ _QL2SC372Y100KHz OSC

03 2SC735Y I_ _BUFF

l

C1601147 ira49V

01.02

2N4280

- - -

P

a -.4: 16:4

4N

LIZ

P - L

O

P8 -10768. .

CA

R 0

4i s

idw

r

I/er

14M

47

Vir

4.41

tieC

111.

30

4 10

4- il

l+ .

soriy

sw

ine

cs a

we,

t ?

-04

9.as

Dr_

sR

i_48

#0.0

10R

// V

O

-0°7

11

01I

Di D

a D

2O

r

R9

CD

nggg

I 44,

i_n_

J11

-J'

IAPi

31

C.-

ileriP

P1/

4471

820

j2)

141.

4---

-h

F -

. . 01

-II

iif

ie?

P i.)

I4-

--1

,,

0 0

2.'4

O

0 0

ufn

1410

0 0 F.

0

Fl

mat

no

v. /I

rv. O

N10

044

ZZ

oV. 2

34V

(3A

)

LJ

XI

tC

1.1

of

L

riff

r

L_

01 .0

4.1 1

1

slsJ

o?D

oo 2

0P

0

I /000

PC

L/0

4; `

.ItC

3I.0

111

yy7.

"1-

.1/4

PiN

2.4

c

AM

/24

-0I.

ozn

,S8

IL3

5 I/56

0.1

IdO

VT

R30

41I

Cto

ol,

c36

0.01

I CZ

6 67

0."

;IO

N ZZ

wY

Rs'

or.4

i11.

2y

-:4

R-1

7

CI

11

C 1

".-1

r-lo

sA

r--

:

V3R

£3

-25

0301

C16

V

/555

56e

og%

0:

C.1

0.0

t18

42

Hes

?ep

ee'

7....

1..1

1.4

Mt

jtio

trzS

a"V

s41/

0t

C36

WO

1.."

-....

,..1q

61I

36

1

th

0410

6?

. 40r-

an 5

6

Ls /0/

.a

IT' 1

11...

fit

13

s 46.1

1

rn In

-SIP

PO

J -"

an

r:0

mow 0S

,

P

4" 4

,056 il

Ls

;::

*

Z Id

,:,*4

0 IM

P

3.5.

14-0T

- -

-A

---1

1.5K

Vit0

-410

7i

CD

I_L

A--

, -t,,

-,

ii, la

tiV

,Lp

La

7.1

ff a

ir -43

.17

Olo

'1%

L89

ti

5482

20

L9 3

00.a

N

ktb*

ah

I lir

I 1

110

.04

SPECIAL PROJECTALL BAND, ALL MODE HF TRANSCEIVER

No compromise performance from high dynamic range circuitry Modular construction: choice of features and complexity Transceiver building blocks can be used to update existing equipment Ultimate design can feature FM/AM/SSB/CW, noise blanking and woodpecker killer, full CW break-in, etc Complete kits of parts and PCBs will be readily available Brand new design by G4J ST/G3WPO Save around f700 on the equivalent commercial Japanese box

APPROVEIZINTRIO

DEALER

THE TRIO TS430 IS NOW AVAILABLEEX STOCK Price £736 - inc VAT &SECURICOR.

ALL B.N.O.S. products available fromappointed MAIN MIDLANDS AGENT

DEWSBURY ELECTRONICS - A FULL TIME SPECIALIST AMATEUR RADIORETAILER WITH A WIDE RANGE OF EQUIPMENT TO SUIT THE MOST DISCERNINGTASTES. ALL THAT IS GOOD IN RADIO - FROM TRIO to JAPAN RADIOCOMPANY.

Dewsbury Electronics otter a full range of Trio Equipment always in stock.We are also stockists of DAIWA - WELTZ - DAVTREND - TASCO TELEREADERS - MICROWAVE MODULES -

ICS AMTOR - AEA PRODUCTS - DRAE

Dewsbury Electronics, 176 Lower High Street, Stourbridge, West Midlands.Telephone: Stourbridge (0384) 390063. After Hours: Kidderminster (0562) 851255

Closed Thursday


A Plainman'sGuide to

s & TowersPart S InstallationThe final step is to decide where tosite the aerial mast or tower youwant, and prepare the foundationsfor it. However, very often, the pro-cess of choosing a suitable site andthen laying the necessary founda-tions can present as many problemsas selecting the mast or tower. So itis advisable not to rush this finalstage, but spend a little time in plan-ning your operation beforehand tosave time and energy later on.

Hiding the thing

If you are fortunate enough tohave a fairly large garden screenedby trees the choice of a suitable sitebecomes a little easier. However, inthe average suburban garden thingsmay not be so easy, space could beat a premium and the choice of asuitable site limited. In general,masts or towers of the telescopic,tiltover type with an extendedheight of 30 to 60 feet would bepracticable, and probably accep-table, in most urban locations wherespace is restricted. Masts and towerswith a retracted height of about 21feet or less can be ideal for suchlocations, because their lowretracted height will enable theaerial to be effectively hidden by theridge of the house, and so reduceany 'skylining' which could be aproblem where appearance is a ma-jor factor (see Fig. 1.) In addition, alow retracted height enables thewhole structure to be tilted over in arelativly small area. Where there

By A S Barraclough G3UDO*

are objections from the neighboursor the local authority against latticetowers then an unobtrusive tubularsection telescopic mast could bemore acceptable. Where a mast ortower can be wall -mounted againstthe side or end of a house, its struc-ture can be masked to some extent.

It will tend to 'blend' in with thehouse. However, the aerial would beclose to the house and may sufferslight detuning, particularly in thelowered position. The amount of anydetuning is not predictable but itshould not be sufficient to cause anymajor problem.

16.

24H TYPICAL

AERIAL HEIGHTRAISED WILOWERED 2211.

AVERAGE TWO STOREYHOUS BUILT 1920,30MORE MODERN HOUSESCAN BE A LITTLE LOWER23 TO 251, TYPICAL

AERIAL HEIGHTRAISED AmLOWERED 311111.

AERIAL HEIGHTRAISED 3611LOWERED 2311

AERIAL HEIGHTRAISED NHLOWERED 26h

RIDGE LINE

A

S

RIDGE LINE

OMIMPOM BIWOVI r 11.11,0071. and RV, V..,

Fig. 1 Typical post mounted mast and towersshowing 'skylining"

42Allweld Engineering

HAM RADIO TODAY JUNE 1983

Post mounted masts or towersneed not be too near any buildingand any detuning would beminimal, but their structures wouldbe more exposed to view. Again if'skylining' is kept to a minimum,with a low retracted height when theaerial is not in use, then the struc-ture may not be too noticable. Whendeciding how far to position thetower or mast from the house, bearin mind the length of feeder androtator cable needed. Long feedercables mean higher losses. Merelyplacing the whole lot as far awayfrom the house as possible may notbe the most economical solution. Asa general guide, keeping the aerialsat a distance equal to at least a half -wavelength (at the lowest frequencyto be used) should be practical.However, as is often the case, localconditions may dictate otherwise.

BOLTTHROUGHWALL

WALL BRACKET

REINFORCINGLATE

WALL&RACKET

Fig. 2 Typical 9" wall section

The other limiting factor is theheight above the hinge point thesupporting bracket up the wall. Asmentioned earlier in part 4, whichconcerned loadings, the higher upthe wall bracket is fixed, the lowerthe the loads on the wall will be.However, it is not possible the fix thebracket to the very top of a wall andhope for the best, because the toppart of the wall is not as strong aslower sections, so some sort of com-promise height has to be found.Generally the wall bracket shouldbe more than three courses ofbrickwork down from the top of thewall but it may have to be lower fora large tower. (See Fig. 2) From thisit is clear that large towers and lowwalls are not compatible withoutsome additional reinforcement be-ing used. The wall bracket is usuallyanchored to the wall either with

Rawall or Para bolts (Fig. 3.), orwith studs going through the wallstructure as in Fig.2. Para bolts areuseful because they require a holethat is only slightly larger indiameter than the actual bolt, so thatthe wall can be drilled through thebracket itself, which saves having tomark the holes out seperately. Wheninstalling the ground hinge and wallbracket always use a spirit level tocheck that they are level and cor-rectly aligned. The manufacturersinstructions should be followedthroughout.

Post mountingWith post -mounted masts and

towers, the stucture is hinged partway up its outermost section andpivoted on a post that is either im-bedded in, or anchored to, a con-crete foundation. Using a winch andcable system, the structure can betilted to the horizontal while it is inthe fully retracted position. The sizeof the concrete base depends on thetype of post and tower to be sup-ported. The manufacturersspecifications will usually state thedimension of the base needed. Dig-ging out the foundation and filling itwith concrete can be a tedious task,but one that cannot be hurried if it isto be done correctly. If you haveany doubts then it may be advisableto get the job done by a localbuilder. Before any concrete is fill-ed, the ground post should be posi-tioned in the hole and held vertical-ly in situ by four guy ropes orsuitable lengths of timber as in Fig.4. Check that it is vertical on allsides with a spirit level, and checkthat only the correct depth of post isbeing buried. Digging out an incor-rectly placed post could be difficultto say the least! Where surfacemounted posts (Fig.5) such as a baseor frame post, are to be mounted,suitable ragged bolts (Fig. 3) areusually called for. A simple way to

ensure that these are correctly spac-ed is to make up a timber patternthat corresponds to the fixing holeson the base. (Fig.6). Fix the raggedbolts onto the pattern and then, us-ing lengths of timber, position thepattern over the hole with the ragshanging down into it. Use a spiritlevel to check that the pattern islevel in all directions before fillingin any concrete. Once the concretehas set, the pattern can be removedleaving the threaded ends of the ragbolts sticking up ready for the baseto be bolted down. Concrete shouldbe allowed to set for at least threedays before handling and a week atleast before any loads can be placedon it. Where a GROUND socket is tobe used (Fig. 7) then the simplestway to bury it is to slip it on to thepost and then set the post up asbefore. It may be a good idea to ar-range some suitable drainage forthe bottom of the socket to prevent itfilling up with water. A simple wayof providing some drainage for thesocket is to stand it on a suitablenumber of engineering bricks plac-ed at the bottom of the hole for thebase. Engineering bricks are thesort that have a number of holes run-ning through them. Bear in mindthat waterlogged ground may not befirm enough for post mounted in-stallations, and this sort of drainagewill not help. If you have any doubtsthen again seek professional advice.Once a post -mounted mast or towerhas been installed, there may besome slight settlement of the con-crete base which, depending on thesoil conditions, may tilt the structuremounted on it.

If you are going to carry out theconcreting yourself you will need toknow roughly what volume of

4. GUYS HOLDINGPOST VERTICALFOR CONCRETING

A S,

Fig. 4 Ground post

MAKE SURE POSTIS PLUMBED USINGSPIRIT LEVEL


material is required. To find thevolume of the base simply multiplythe area of the bottom of the hole byits depth. Thus:

Volume = A x A xBcubic feet or metres. (See Fig.

4.)The weight of concrete in the

base can be found by multiplyingthe volume base by the weight ofconcrete per cubic foot/metre. Theapproximate weight of concrete is1441b per cubic ft, or 230kg percubic metre. Buying the concreteready mixed or having it mixed onyour premises by a contractor isprobably the cheapest and quickestmethod. If you are going to makeyour own then a mixture in the pro-portions 2:4:6 of cement:sand:coarse aggregate/broken-brick-filling should do the job pro-viding the mix is not too dry and thehole is properly filled with it. Insome circumstances, where thespace available for the base is a littlerestricted, or when the soil is a littleloose, it may be necessary to in-crease the resistance of the soil byspreading the loads over a largerarea. This can be done easily bydriving suitable lengths of steelangle or 11/2 to 2 inch diameter pipeinto the soil near the bottom of thehole, leaving a foot or so of the steelreinforcing sticking into the holeitself so that it will become embedd-ed in the concrete when the hole isfilled (See Fig. 7.) But remember,this is not a subsititute for a properconcrete base. The manufacturersspecified dimensions should befollowed.

EarthingA conductive metal structure

such as a mast or tower can be af-

fected by the RF being transmittedat the aerial as well as by static elec-tricity in the air and lightning.

In order to minimise these ef-fects and eliminate the possiblitiesof getting an accidental staticdischarge, or the tower beingdamaged by a lightning strike, it isadvisable to ground the structure toa suitable 'Earth' point. This can bedone by burying up to 3 or 4 feet ofcopper rod (about 3/8" diameter) ora similar length of copper waterpipe and then bonding the base ofthe mast or tower to it, using a flatstrip of copper about 1" wide at least1/16" thick (16 or 14 SWG). Ear-thing the tower in this way will alsoreduce the likelihood of any RFpick-up being reradiated, causingthe inevitable TVI.

EXTRAREINFORCINGBARS IN SOIL

TYPICALa,- GROUNDSOCKET

11111110.

ENGINEERING BRICKSSUPPORTING SOCKET HOLES

Fig. 7 Ground socket

SafetyLike all mechanical devices, a

mast or tower can be dangerous if itis incorrectly used, poorly maintain-ed or overloaded. Remember thatsafety and performance will dependto a large extent or correct usageand regular maintenance. Most of

the problems that arise with mastand tower installations are due toone or both of these factors being ig-nored. When you are decidingwhere to position the tower, bear inmind its full retracted length, in-cluding the aerial array, and markout where exactly it will come whenlowered down.

Some do's and don'tsDo read all the manufacturer's in-structions before carrying out anyoperation.Do observe the manufacturer'sspecified loadings.Do inspect regularly for wear andtear.Do lubricate such things as pulleysand cables regularly.Do support the weight of the struc-ture when it is horizontal.Do check that cables are seated intheir pulleys before any winchingoperation.Don't overload the structure.Don't tilt over with the mast or towerextended.Don't allow anyone to stand in its'line of fall' where tilting down.Don't rush the operation or let an in-experienced person carry it out.Don't heave and pull on the end ofthe structure while it is tilted overand unsupported.Don't leave the mast or tower fullyraised when you go on holiday.Lower it and immobilize it or lock it.Don't leave yourself uncovered byinsurance.

That's about it then, with a cor-rectly installed mast or tower pro-perly used and well maintained, youshould be able to keep your aerialsin tip-top condition and enjoy manyyears of happy amateur radiooperating.

TIMBER PATTERN FRAMEHOLDING RAG BOLTS INPOSITION FOR CONCRETING


By Richard Lamont G4DYAAssistant Editor. Ham RadioT

After being bitten by the amateurradio bug, the newcomer is often ata loss to know how to start. At first itmay seem that all that can be done

is to bone up on the RAE and theMorse test needed to get a Home

Office licence.

Although the idea of just listening toradio amateurs may seem a bit bor-ing compared to actually talking tothem, it really can be a fascinatinghobby in itself. I spent a couple ofyears (not all of it!) glued to a shortwave receiver before getting alicence, with never a dull moment,because there is always somethingnew to discover. Like the transmit-ting amateur, you can explore themysteries of the ionosphere as itcontinually changes in the way itbends radio signals around theEarth's surface - sometimes slowlyand subtly, sometimes so suddenlythat you think a fuse has gone. Thispropagation of radio signals is onearea of fascination. Another such isaerials - there is an infinite varietyof aerials for different jobs, andendless scope for building, modi-fying and testing out your ideas andlearning by experiment.

There are countless morereasons why SWLs the world overare content to just listen and not

talk. They're willing to leave a'ticket' until they've solved thechallenges and answered the ques-tions that SWLing inevitably brings.

If you've got this far and notdecided that I'm honkers then stickwith us. The purpose of this article isto show the complete novice aroundthe controls of a typical, reasonablymodern, receiver or transceiver.Yes, while we're at it we might aswell deal with the transmitting bits- they're easy. Let's find our wayround the receiver first.

The first thing is to set thereceiver to the right frequency, ie.somewhere in our chosen amateurband. (The bands allocated foramateur use are listed in Table 1. )There is always some kind of band -switch which is marked in eitherfrequency, measured in Megahertz(MHz), or wavelength (measured inmetres). The table shows how thetwo quantities are related. note thatas the frequency gets higher, thewavelength gets shorter.

Some bandswitches have a posi-tion marked WWV or JJY. This isusually a 10MHz band for listeningto 'standard frequency' transmis-sions to check the receiver cali-bration.

Having chosen which band tolisten on, the next step is to masterthe main tuning dial. There is ahuge variety of these, but the easiestto read are the digital ones. Theseare included on virtually everymodern rig. Older receivers oftenrely on a combination of two'analogue', mechanical indications-a 'course' indication, usually on adial behind a plastic window, and a'fine' indication, often on a 'skirt' onthe tuning knob itself. The skirt canusually be moved independently ofthe knob, enabling exact calibra-tion. These dials reached nearperfection in the Seventies, just intime to be ditched by digitals.

Crystal calibrator

Although these 'analogue' tun-ing dials can be set accurately, anaccurate reference is needed to setthem with. A crystal calibrator is theusual answer. This is a very accu-rate crystal -controlled oscillatorthat produces an output at severalfrequencies across the short wavespectrum, typically 100kHz apart.The trick is to switch the calibratoron and 'tune it in for zero -beat'; ie.adjust the dial until the pitch of thetone coming from the loudspeaker isso low that you can't hear it. Thenadjust the skirt to the '0' position,without moving the main control.The receiver is now calibrated - at

Frequencyrange(MHz)

Approximatewavelength(metres)

1.810-2.000 1603.500-3.800 807.000-7.100 4010.100-10.150 3014.000-14.350 2018.068-18.168 1721.000-21.450 1524.890-24.990 1228.000-29.700 10

Table 1: HF amateur bands (in UK)

least for that band. Try checking thecalibration up and down the band tosee if it's OK at other 100kHz points.

Another commonly found con-trol connected with setting the fre-quency is a preselector knob. This


simply 'peaks' certain parts of thereceiver for best performance at thechosen frequency. Simply adjust formaximum volume.

Intermediate frequencyAll receivers, except direct

conversion ones, change the fre-quency of the incoming signal to anintermediate frequency (IF) fairlyearly on. This is because it is easierto amplify and process a signal at asingle frequency than over a wholerange of frequencies. The inter-mediate frequency signal is even-tually demodulated into audio.

ModesThere are several different ways

of transmitting speech. On the HFbands Single Sideband (SSB) isused almost exclusively. There aretwo sorts of sideband - upper andlower (USB and LSB). On amateurbands below 9MHz it is usual to useLSB, whereas USB is the normabove 9MHz.

AM is rarely used by amateursnow, but it's useful to have it if youwant to listen to broadcast stations.FM is very valuable if you envisagelistening to the VHF and UHFbands, either on a VHF/UHFreceiver or on an HF receiver with aconverter.

CW stands for continuous wave,a rather inaccurate and old-fashioned term for Morse Code.(How can it be continuous if it's be-ing keyed on and off?) The only dif-ference to the receiver, compared toSSB, is that the filter used has a nar-rower bandwidth. The bandwidth isthe difference between the lowestand highest frequencies it will letthrough. Morse consists of a tone ofconstant frequency that is keyed onand off (whereas speech uses a con-tinuous range of frequencies) so anarrower filter will do.

When you discover how manysignals are squashed into the shortwave spectrum you will understandhow important bandwidth is. Youcan minimise interference to the sta-tion you're trying to listen to byminimising the strength of stationson neighbouring frequencies. Inother words you minimise thebandwidth.

Older receivers had switchedfilters, with bandwidths to suit themode in use - typically 12kHz foramateur FM, 6kHz for AM, 2.71(Hzfor SSB and 600Hz for CW.

Modern receivers often have IF

shift and IF width controls whichallow continuous variation of thefilter's response. Figure 1 shows theeffect of these controls. A typicalcrystal filter for SSB reception mightbe, say, 2.7kHz wide, symmetricalabout the intermediate frequency(IF). Turning down the IF widthmight reduce this to, say, 1.8kHz.This would spoil the audio quality abit, but it would certainly cut out'adjacent -channel' interference.

The IF shift control doesn'taffect the bandwidth, but moves theresponse up and down. It sounds abit like turning the 'bass' down andthe 'treble' up, or vice -versa.Again, this control can be used toget rid of interference on a close (oreven overlapping) frequency.

Some rigs, eg. the Trio/Kenwood TS930 transceiver, do nothave IF shift and width controls, butseparate controls to move each sideof the filter's response up and downin frequency.

the RF gain, which controls theamplification of the earliest stages ofthe receiver. The drop in volumecan be offset by turning up the AFgain, which controls the amount ofgain in the last stages of thereceiver. If, however, you turn theRF gain down too low and the AFgain up too high, the signal in mostof the receiver's stages will be toolow, and it will reward you with hiss.

For SSB reception it is advisableto keep the RF gain set lowish forgood audio quality.

Automatic gain control(AGC)The range of signal strengths on

the short wave band varies enor-mously from one transmission toanother, so it's desirable to reducethe receiver's gain automatically onstrong signals. This reduces risk ofoverloading, and prevents you fromdeafening yourself when a strongsignal appears.

Filter lossdB 0

6

20

40

60

Normal filter response

Effectof IFpsirft control

I Effect of IF width controls

1

1

1

1

-2 +2Frequency kHz

Fig. 1. Effect of IF shift and IF width controls on filter response.

-1 IF

Gain controls'Gain' means the amount of

amplification in the receiver. Thevarious stages inside the set will,among other things, graduallyamplify the signal bit by bit until it'sstrong enough to drive theloudspeaker. However it is impor-tant that the signal in each stage isof about the right voltage. If it's toostrong, the stage will overload andproduce cross -modulation. Thismeans that you will hear inter-ference from stations on differentfrequencies to the one you're tunedto. This can be avoided by reducing

A good AGC system has a fastattack and slow decay. The fast att-tack means that when a strong signalappears, the AGC will cut thereceiver's gain down very fast in-deed - typically in a thousandth ofa second. The slow decay meansthat when the strong signal goes, thegain is wound up slowly, so that ifthe signal reappears after a briefpause (such as the pause betweenwords) the gain is only slighly toohigh and can be corrected easily.

Many receivers have a fast andslow AGC switch. Slow is normallythe best for SSB reception, because

46 HAM RADIO TODAY TUNE 1983

the background noise is not broughtup as much in the pauses betweenwords. If, however, the signal is suf-fering from 'flutter fading', whichsometimes happens, the faster posi-tion can help the AGC cancel outthe variations in signal strength.

Noise blankerThere are all sorts of both

natural and man-made interferenceon the short wave bands. Noiseblankers are designed to get rid ofinterference that consists of short,strong pulses. Interference from acar's ignition system is like this. Theeffectiveness of noise blankersvaries enormously from receiver toreceiver and from one type of in-terference to another. The only ad-vice I can give is try them out.

Clarifier/ RIT/ IRTThese are all names for the same

thing. The allow you to move areceiver's frequency a few kHzrelative to the main dial. This is veryvaluable for listening to SSB con-versations, where two stations may(for a variety of reasons) not be onexactly the same frequency.

SquelchThis isn't as disgusting as it

sounds. It is simply a gadget thatcuts off a receiver's audio if there isno signal at the input. This cuts outthe irritating hiss. Squelch controlsare universal on FM receivers butrare for SSB.

Transmitter controlsSo far we've dealt exclusively

with a receiver, or the receiving

section of a transceiver. Thetransmitting parts are, perhaps sur-prisingly, simpler. The main trick tolearn is 'tuning -up', and even thishas been eliminated by the latestsolid-state designs.

Tuning up is the process of mat-ching the power amplifier, ie. thefinal stage of transmitter, to theaerial feeder cable. Matching isnecessary to ensure the most effi-cient delivery of power from the PAto the feeder - if any power isn'ttransferred it does not just disap-pear, it heats up the PA com-ponents. With a severe mismatch, aPA can suffer serious damage.

Most rigs have two PA tuningcontrols. The first is marked tune,tuning, anode or plate. The secondis marked loading. To tune up setthe controls to the position recom-mended in the instructions. Make

sure that the aerial, or better still adummy load if it's the first time youhave attempted this, is connected tothe rig's aerial socket.

Turn the mic gain/carrier/drivecontrol fully anticlockwise andswitch the mode switch to CW /tune.Switch to transmit. Measure the PAanode current on the meter - thereis often a meter switch to select dif-ferent measurements. Adjust thecarrier and preselector controls toincrease the current, but not toomuch! If necessary back off the car-rier, then peak the preselector formaximum.

Having got a bit of drive to thePA the next step is to resonate theanode circuit. Adjust the anodecontrol of minimum current.

After this stage the PA shouldbe 'fine-tuned' to optimise the out-put power. The loading and anodetuning controls should be alternate-ly adjusted for maximum RF. Thisshould be done at maximum drive.

Having tuned up the PA the on-ly other important adjustment is toset the mic gain or carrier control(depending on whether you're usingSSB or Morse). The manufacturerusually gives instructions on how toset this. The important thing is toavoid tuning the mic gain to high onSSB, because 'flat -topping' can oc-cur, causing your signal to 'splatter'onto adjacent channels. This wouldnot make you popular!

Driving a transmitter is easy; it'sthe receiver that takes the skill. It'swell worth SWLing before getting alicence to learn how to operate one.What's more in the process you'llpick up a lot of tips that'll help youthrough the RAE.

RIT - allows you to move a receiver's frequency a few kHz, 4., K., .),(4-

3 i USB

k

WO.

(0---7-o---...

*............, ,,,-...

..;-,.2.N,o \\

RIT0

\ I ,/SQUELCH

.cALop4

BAND

AFGA IN


A Simple AmateurTelevision Station

Adding a keyboard tothe character

generator.

So far in this series of articles I haveshown you how to build a video testsignal and sync pulse generator(Part 1), and how to display yourcallsign or QRA etc. electronically(Part 2).

In Part 3 I would like to showyou how to add on electronickeyboard to the character generatordescribed in Part 2. This uses analternative module to the diode pro-gramme unit. The charactergenerator in Part 2 was made up oftwo printed circuit boards mountedone above the other, with the diodematrix card being the uppermost, soas to facilitate plug-in modules pre -wired for different messages. Whenworking portable (as in a contest)this system is ideal. All you need todisplay is one four -figure group ofdigits, which remain unchanged forthe entire contest.

When we use our TV station inless strenuous conditions, eg. aquiet evening amusing three or fourlocal stations, then our supply ofpre-programmed messages will soonbecome exhausted. The moduledescribed in this article is pin -compatible with the diode matrixmodule and will simply plug-in inplace of it. A standard ASCIIkeyboard can then be connected tothe new module's input and it isready to type directly onto thescreen. The new module also has apage switch to facilitate up to eightpages of text so messages can bepreset and 'brought on line' at theflick of a switch.

The pins J, K, L, M, carry a 4 -bitaddress code from the charactergenerator which changes every timeit scans a different character. Thiscode was used to address a differentlocation in the diode matrix and br-

ing on line to the data bus (B, C, D,E, F, G, H,) the information that wasset by the diode programme in thatlocation.

By Trevor Brown G8CJS, GeneralSecretary, British Amateur

Television Club

In the new module this 4 -bitaddress code selects a location inRAM (Random Access Memory).When the memory is addressed the

Fig. 1. Block diagram of keyboard add-on unit.


information in that particular loca-tion is available to the data bus, injust the same way as the diodematrix.

The next stage is to be able towrite to the RAM. To do this we needto bring the keyboard onto the databus. An ASCII keyboard has sevendata outputs, and supplies a code tothese outputs dependent on whichletter is selected. The keyboard alsosupplies a short pulse called'strobe', every time we press a key.This strobe pulse could be 'activehigh' or 'active low'. Most keyboardsprovide both.cnDur circuit requiresactive low, often called ST. Whenthis signal occurs the outputs of IC 1,(74L5244) which arg normallyfloating, assume the same state asthe inputs and thus feed thekeyboard output to the data bus.The strobe pulse also passes to theRAM where pin 10 of our memorychips (2114) are driven low. Thisputs them into a 'write mode' so thekeyboard data is stored.

The next problem is to controlwhere the keyboard data is stored.By inserting IC4 in the address linesto the RAM we can switch the ad-dress lines in the write mode. IC4(74LS157) is a 4 -bit data selectorand functions just like a 4 -poledouble -throw switch, in that whenpin 1 is driven low the RAM addresslines are fed from the QA, QB, QC,QD outputs of our counter chip ICS.

IC5 is a counter which countsup to 16 and then resets. By usingthe strobe pulse to advance it, itscount will increase by one everytime we press a key, ensuring thatthe selected letter is stored in thenext location in memory. When IC5has been clocked to location 16 itwill automatically reset to characterlocation 1.

The next stage is to display a'cursor' so that we can see the nextlocation to be typed into on thescreen. To do this we compare the'read' and 'write' addresses in the4 -bit magnitude comparator IC6(74LS85). When the two addressesare the same ie. the charactergenerator is scanning the locationwhich we will next type into, thenthe output of the comparator, pin 6,goes high. This high state is con-nected to pin 8 of our RAM which isthe chip enable pin (active low), sowhen our two addresses are thesame the RAM is disabled, causingthe data bus to be pulled high by the10k pull-up resistors. This ensures

Fig. 2. Wiring side of double sided PCB

O

0 0 0 0 0 0 0 00%0

0

0

0-O

O0

0

o-

O 0,0,

0

00-0

CO --0

Fig. 3. Component side of double sided PCB

N

MC R

UN

L ) SK T

RILINK

G

F

D

B

A

C

Fig. 4. Component layout

C

C

C

C

C

ALL RESISTORS 10kALL DIODES 1N914CAPACITOR 100u

\INK

KEY-

BOARD

INPUT

SEE

TEXT

the data bus assumes a high state inthe absence of RAM data.

If the diode programme moduleis operating erratically then the ad-

dition of these pull-up resistors tothe diode module may be theanswer. It depends upon the diodesused.


Fig. 5. Circuit of keyboard unit+0

5V

7.106

741.5244

1

1

le

Bo

Co

51

7

16

Go121

91

No-17.5.

1 o IPao.witch

5.5017

711)

3.10k

13 129',44.

IC 2

2114

NI

3 Ic 12 II

2 3 6 f7

1C3

21 4

1 2 3

17

r9

figCur.., on

.5.1106

1N914

11 I4

61W9

10

4 ICB

II 13 I

7 1.5115

9

14 IS 10

ICs74.1..5191

6 3 2

71.4500

3 1

1is!

171

Its 91

1151

14

74E030

ICI IC7

10

5.

fig-1IL--J

If all the data bus bits are highthen our character generator willgenerate a white block, whichmakes an excellent cursor.

The full ASCII code providesmany things besides characters in-cluding cursor functions such asCURSOR HOME, BACK SPACE,DELETE etc. In order that this cir-cuit is kept simple I have not decod-ed or used these functions, exceptcode 7F (or keyboard outputs equalto 1, 1, 1, 1, 1, 1, 1, if you prefer).This is the DELETE code. IC7(74LS30) is a 8 -input NAND gatewith 7 of its inputs looking at thekeyboard output, so when the delete

code is presented by the keyboard,the output of IC7 will be low. Thissignal is inverted and fed into ourcounter which has the following ef-fect: when our counter is clocked bythe strobe pulse it will count downinstead of up. The output of 1C7 isalso used to inhibit and write signalto our RAM so the cursor will stepback and the information in theRAM remains unchanged. In effectwe have created a 'backspace' func-tion; probably the most useful cur-sor function for a small charactergenerator. The use of the DELETEkey for this function instead of thebackspace key simplifies our circuit

Fig. 6. Component overlay. Unused holes should be linked through

N

M

K

j

14

G

F

E

D

C

B

A

KE YBuARD

INPUT

S5 E

TEXT

and does not cause too muchoperator confusion as keys like thisare rarely used in a touch typemode.

Si is used to remove the cursor.Closing it inhibits the chip enableinput of the RAM from going high,the state that generated the cursor.

The page switch is optional andif not required pins 1, 2, 3, of theRAM should be connected toground. Note provision is not made(on the PCB) for the 3 x 10k pull-upresistors associated with this switch.These are best fitted directly to theback of the switch.

The only problem left is in con-necting up a keyboard. I used anRCA CP601. The output is via a PCBmounted socket, which takes a 3Mconnector No. 3421-6020. I haveshown how to connect that par-ticular keyboard to my circuit by in-dicating pin numbers.

Those of you with otherkeyboards the strobe required is ac-tive low. The data outputs connect topins 11, 8, 4, 13, 15, 2, 6 of the74LS244 in that order, wtih pin 11being the least significant bit.

If you want to avoid buying akeyboard the Amateur TelevisionHandbook Vol. 2 gives details ofhow to build your own, or how tocontrol ASCII codes by using BCDswitches.

The book is available fromBATC Publications, c/o G 31QUQTHR.


TechnicalitiesFerrite based transformers offer one of themost powerful design tools available tothe radio amateur. They can both isolateand match lumps of circuitry over thecomplete HF spectrum with virtually noloss. It is almost unthinkable to build apiece of gear without using them in someform or other so I make no apologies forpresenting them in the Technicalitiescolumn.

Although RF transformers aremanufactured from ferrite or dust ironcores, they use exactly the sameprinciples as transformers operating atany other frequency. A current flowing inthe primary coil induces a magnetic fluxin the core. A second coil interceptingthis flux, ie. wound on top of the first one,produces a voltage proportional to theapplied AC voltage and the ratio of theturns between the two coils.

As with 50Hz mains transformers,there are limits. The primary representsan inductance in parallel with theapplied voltage. If the inductance is toolow, the circulating current will causesuch intense magnetisation of the corethat it will saturate it, and the losses willincrease dramatically. Many people willhave heard and smelt the distress of amains transformer inadvertentlyconnected to its 115V tapping. RF trans-formers can saturate in precisely thesame way, but more about this later.

Small signal, widebandwidth

Regardless of the operatingfrequency or core material, thetransformer law, as shown in Fig. 1

applies. The turns ratio (between primary

Fig. 1. The turns ratio is thesquare root of the impedanceratio.and secondary) is the square root of theimpedance ratio. Put another way, theimpedance ratio is the square of the turnsratio. If you wind nine turns on a ferritebead (excellent for small RF transformers)and then a further winding of three turns,a load of 50 ohms attached to the threeturn winding will be transformed to a 450ohm load as seen across the terminals ofthe nine turn winding. For those with apractical view, three turns on a ferritebead in parallel with a 50 ohm source willhandle up to about 100mW of power -

Broadband transformerdesign by Frank Ogden G4JST,

Editor Ham Radio Today

transformed to an impedance dictated bythe number of secondary turns - acrossthe range 2 to 70MHz. Precisecharacteristics though will depend on theferrite material from which the bead wasmade. An alternative statement oftransformer law is shown in Fig. 2.

Where x - number of turns onprimary and y number ofturns on secondary

Fig. 2. If you know the turns ratioof a transformer and theimpedance connected to one sideof it, you can calculate theimpedance 'seen' at the otherside of the transformer.

Figure 3 offers a very practicalapplication of simple widebandtransformer design. This grounded gateJFET preamp provides about 14dB of verylow noise gain right across the range 1 to30MHz. Above 30MHz, there is a gentlefalloff in gain; the unity figure is reachedaround 100MHz. Strangely, the gainslope has almost nothing to do with theferrite transformer and everything to doabout circuit parasitics. The transformeris shown wound with a ratio of 5:1. Thistransforms the 50 ohm output load to

Fig. 3. A broadband low noise RFpre -amp

1250 ohms at the JFET drain. The deviceoutput capacitance is about 5pF. Theupper computer graph shows thepredicted response due to the loadingeffect of 5pF across 1250 ohms. The realplot would show slight ripple due to theleakage inductance of the transformerresonating with this capacitance.

The effect of capacity loading insmall signal broadband transformers isclearly shown in the second plot. Theturns ratio has been increased to 10:1.Although the circuit gain now rises to20dB, the frequency rolloff is much moremarked. In this, there is a profound truthfor the circuit designer: the bandwidth ofa circuit is inversely proportional to itsgain. The parasitic components whichdetermine the gain of the circuit shown inFig. 3 are brought out in Fig. 4. Thesample holds one more lesson which isdirectly related to the ferrite material.The transformed load resistance, Rp ifFig. 4, is directly in parallel with theprimary inductance of the transformer.The lowest operating frequency will bedetermined when the inductivereactance of the primary winding has thesame value as the transformed loadresistance. Since the transformer primaryinductance will be a function of the corematerial, the LF frequency response istotally dependent on the grade ofmaterial used in the core. Furthermore,the core is most likely to saturate at thebottom end of the range.

OUTPUT TO 50R LOAD

P 10 TURNSS = 2 TURNS

C -r-

/7k7

Rp - 1250RC = OUTPUT

CAPACITANCE- 5p0 FOR J310

Fig. 4. The unseen components ofFig. 3. It is these, and not thecharacteristics of the ferritewhich largely determine thefrequency response of abroadband circuit.

Leakage inductanceThe earlier circuit example showed

that high impedance, transformercoupled broadband circuits exhibited abandwidth determined mostly byexternal loading capacitance. Ittherefore came as quite a shock to me


T1

C1

Vs*12V

V bias

Fig. 5. Output circuit of a typical

12

C2

L1

I O

100W HF transistor PA

when I saw high power transistor circuitswith extra capacitance added in parallelwith the windings. It struck me as veryodd indeed.

Figure 5 is just such a circuitexample. It depicts the standard 12V100W broadband HF PA stage usingstacked ferrite rings as the basis for theinput and output transformers. Thetransistor input and output resistancesare very similar at this level of power andsupply voltage. Without going into toomany details, please accept as fact thatthe ratio between primary and secondaryon T1 should be 4: I , and 1:4 on T2. Why isCl across the primary of T1 (typical value150pF) and C2/L2 across T2 (typicalvalues 220pF, 100nH)?

The answer is leakage inductance. IfT1 and T2 were perfect transformers, theextra components would not benecessary. In the real world, the total fluxinduced by the primary circuit does notcompletely encompass the secondarywinding with the result that some of thismagnetic path 'gets lost'. This is likeadding a low value inductance in serieswith both the primary and secondarywindings. This has all sorts ofimplications.

High power

In high impedance circuits, such asthe preamp of Fig. 3, leakage inductancedoesn't matter too much. As I said earlier,the most that it will normally do is to causea ripple in the frequency response. With atypical value of a few nanohenries for asmall transformer, this series reactance isvery low compared with the loadimpedance, even at the highest operatingfrequency. In the circuit example of Fig. 5the load impedances are in the region of acouple of ohms at most. It only takes atouch of stray inductance to insertunacceptably high reactances in serieswith the load. The effect of these is toreduce the current swing available in theRF signal. In uncompensated circuits, thehigh frequency falloff in output power(and gain) is very marked. A design which

delivers 100W at 3.5MHz may only givearound 40W at 29MHz. Similarly, theavailable gain may fall from 20dB to 8dBor less. Unfortunately, the falloff due toleakage inductance in the transformerslooks almost identical to the rolloff curveof poor quality PA transistors. It is nowonder that many people are leftscratching their heads aboutdisappointing performance.

The answer lies in the arrangementsshown in Figs. 6 and 7. You can't design abroadband transformer which doesn'thave leakage inductance. You have tofind a way of living with it. Like all thesethings, there is almost a conspiracyagainst the RF designer. To buildpowerful amplifiers you must usecomponents, ie. ferrite transformers,which are man enough to handle theexpected power. This means that theymust be large. The larger they are, themore leakage inductance they mustexhibit therefore the worse the problemis. You have to treat the leakageinductance as if it was a separatecomponent. In Fig. 6, a schematicrepresentation of the input circuitry, the

stary inductance is resonated with thecapacitor C 1 . In theory, C1 could beconnected in series with the primary toform a series resonant circuit. However,this would provide cancellation at onefrequency only. Connecting Cl as shownproduces a less complete, but adequatecancellation over a much widerfrequency range. On the LF side, C 1 has ahigh reactance and T1 performs its job inthe normal manner. As CI starts toresonate with the leakage inductancetowards the HF end, the impedance at theinput rises although not excessivelybecause the Q is low. The equivalent of2:1 SWRs can easily be tolerated at theinput which is the sort of value that mightbe expected across the range 1 to30MHz. A more complete conpensation isrequired on the output transformer.

The output circuit

Figure 7 shows the schematicdetails. If a transistor output stage is todeliver a specified output power over theHF spectrum, the load resistance whichthe devices actually see needs to be keptto within around 10 per cent variation onthe mean value. In this case, leakageinductance is accomodated by making itpart of a T filter arrangement with a rolloffdesigned for just above the operatingrange. The stray inductance provides onearm and LI provides the other. C2 acts asthe bottom of the T. In practice the onlyway to find a value for LI and C2 isempirically. There are people who saythat this type of network can becalculated but, frankly, I don't believe it.In a 100W design, insert about 80nH forLI and around 100pF for C2 as ballparkvalues. Chop and change until you obtainthe most level response. The precisevalues will depend completely on thecharacteristics of the transformer, so thatshould be designed first. (I suppose thatgoes without saying.)

INPUT

LEAKAGE INDUCTANCE OF TRANSFORMER

T1

Fig. 6. Tuning out the leakage inductance. Capacitor Cl is chosento resonate with the leakage inductance at the highest frequencywhich the transformer is required to match.


RF power transformerdesign

This is a pretty complex business andI propose to deal with the 'how' ratherthan 'why'. You need, at minimum, toknow the following things about theferrite material. I have assumed the use offerrite rings typical of the power designsusually published. I have also assumedthat one winding of the transformer willoperate to or from a 50 ohm load. Theother winding is dictated purely by thetransformation requirements. You mustknow:The outer diameter of the ring: Do (mm)The inner diameter of the ring: d(mm)The height of the ring: h (mm)The relative permeability: yrThe turns ratio of the transformers: n(this assumes that the secondary, thecollector or base winding, will comprisea single turn made out of copper orbrass tube, and that n will be thenumber of turns on the primary forconnection to a 50 ohm load)The minimum operating frequency:Fmin (MHz)The power to be transformed: Po (Watts)The power loss per cubic cm of ferritematerial at a given frequency andspecified magnetic induction: Ploss(mW)The last two quantities need only beknown if loss calculations are to be made.Other quantities: yo (permeability offree space) = 4 x Pi x 10-7First calculate the cross sectional area ofan individual core: s (m2 )s = h x (Do -d)/2 x 10-6 square metres

Ll

Fig. 7. If a transistor PA is to develop its full power over the range1.8 to 30MHz, the transformer leakage inductance must be carefullycancelled out over the same frequency span. The inductance ismade to form part of a 'T' filter arrangement with a characteristiccut-off frequency just above 30MHz.

Next, calculate the magnetic pathlength: 11 = (Do -((Do -d)/2)) x Pi mmNow you need to know the minimuminductance which the circuit design cantolerate. Generally, a minimumreactance of 150 ohms will be adequatefor a 50 ohm system.Lp -= 150/2 x Pi x Fmin tAFIThe number of ferrite cores, Nc, requiredto achieve the desired performance is:Nc = (Lp x 1 x 10-9)/ (yo x µr x n2 x s)Round the value Nc up to the nearestwhole even number.To work out the system lossesv, the maximum peak voltage across theprimary (50 ohms) is calculated:v = square root of (Pox 100)

Work out the maximum induction withinthe core: B (mT)B= 10 x(v/(2 xPixFminx103xnxNcxs)) mT . . nifflaeslia

Next work out the volume of the core incm3Vol = Pi/4 x (Do2 - d2) x h x Nc x 10-3The total power lost in the core = vol x

Ploss mWI have devised a computer programsuitable for the Sinclair Spectrum whichtakes the chore out of transformer design.The listings and program output havebeen included. For guidance, the typicalloss figure for ferrite materials with a pr inthe region of 100 to 200 is 200mW/cm3 ata maximum induction of 12mT at1.8MHz.

5 REM -Broadband-10 PRINT "Enter details of tor

old cores"15 PRINT "Fill dimensiOns to be

in ma -20 INPUT "Specify outer diamet

er ;Do30 CL540 INPUT .dialeeter -;450 CL560 INPUT "Rod the height ":h70 INPUT -Specify relative pe

rmeability .ur80 PRINT "Next; the turns rati90 INPUT "How many turns on pr

imary? -;0100 CL5110 LET uo=4*PI*10t-7120 LET s.hie(tDo-d)/2)e40i-6130 LET tDo -ttDo -di .,2)) eP/140 PRINT -Primary inductance"145 PRINT "This assures reactarce".-is equal to three times ":operating impedance normalised","to 50 ohms -150 INPUT "Specify lowest frequ

encg mHz -,Fmin155 CL5160 LET Lp.INT (150/l2*PI*Frini

): PRINT "Primary inductance = '

X.

uM-170 LET Nc=INT ((l-Pel*I0T-9)/(u

°mut-et-11'2'5)4..5)175 PRINT_120 PRINT -15 PRINT186 PRINT "Outer diameter ';Do;

187 PRINT188 PRINT "Inside diameter -;d.;189 PRINT190 PRINT191 PRINT192 PRINT "Relative permeabilit"r193u PRINT194 PRINT -Minimum frequency

Fmin; "MHz"195 PRINT200 PRINT -Number of primaryrns = "r1

"Height -;P';'-ca"

205 PRINT220 PRINT "Number of cores = ";

Nc225 PRINT230 INPUT "Enter transferred pc,

wer tU)",-assuming a 50 Ohio matched -,"load ";Po240 LET v.SOR famPom50)250 LET 5=INT (10m(v.,12ePIeFmin*10t3eneNces))),10: PRINT "Max i

nduction = ';B;"aT"260 INPUT "Power loss density o

f ferrite";"material at the maximum flux","induction level and the minimum -;-frequency: teUfcal3";Ploss270 LET vol=PI,4*(Dot2-d12)mheN

cit.10t-3280 PRINT290 PRINT "Power loss in cora i

s -;INT (Plossmvoi.).:"sif","at -;Po;-) transferred power Lave.t-

Fig. 8. Sinclair Spectrumtransformer design program.

Outer diameter 12.7maInside diameter 6.35msHeight 8.35mm

Relative perseabitity 220Minimum frequency 1.8MHzNumber of primary turns =

Number of cores = 8

MaX andUCtiOn = 12.9UTPower Loss in core SS 246SmiJat 50u transferred Power iEWCk

tL Fig. 9. Program output (above)

d8/div

1

r

arder

Fig. 10. The two computer plots(above) show the effect of outputresistance changes on frequencyresponse for the circuit shown inFig. 3.


RADIO TOMORROW7-8 May 432/1296/2320MHz Contest (rules in March

Radcom)CQ M Contest (rules in April Radcom)

8 May 144MHz Low Power ContestLincoln Hamfest, Lincolnshire Showground,11 am-5.30pm, talk -in S22 & SU8.Mid -Ulster Amateur Radio Club Rally,Parkanaur House, opens 12 noon.

11-14 May Nu Piscids meteor shower (max 12 May)14 May GB2WEC special event station at the Old

Power Station, Bargates, Christchurch,Dorset. (Home of Wedgewood ElectricalCollection.) On air 10am-5pm, 2m FM &80/20/15/10m SSB/CW. Special QSL card.

15 May WAB LF Phone Contest (rules in AprilRadcom)Region Round -up Contest (rules in AprilRadcom)Swindon Radio & Electronics Rally, 10am,Park School, Marlowe Avenue, Swindon.Talk -in S22 & SU8.Northern Mobile Rally, The Great YorkshireShowground, Harrogate; opens 1 lam(10.45am for disabled visitors), talk -in.

16 May Radio Amateurs' Exam21-22 May 144MHz Contest

22 May British Amateur Television Club Exhibition,Post House, Leicester.432MHz CW Contest (rules in MarchRadcom)RATEC 83 Rally, South Manchester, 11am-5pm, talk -in S22.

22 May(contd.)

29 May

Barry College of Further Education RadioSociety - Welsh Amateur Mobile Rally,Memorial Hall, Barry, 1 lam-5pm, talk -inS22.East Suffolk Wireless Revival: rally at CivilService Sportsground, Bucklesham, Ipswich.Plymouth Radio Club Rally: 10am, TamarHigh School, Paradise Rd., Stoke, Plymouth.Talk -in S22 & SU8.

Arietids Meteor Shower (max 8 June)Zeta Perseids meteor shower (max 8 June)National Field Day (rules in FebruaryRadcom)Phase IIIB satellite launch on Arlene 7

5 June Spalding Rally, at Springfields, Spalding,Lincs. Talk -in S22 & SU8. Opens 1 lam.

12 June 70MHz ContestRNARS Mobile Rally, HMS Mercury, Nr.PetersfieldElvaston Castle Mobile Rally, ElvastonCastle Country Park, near Derby, 10am,talk -in.

19 June Denby Dale Amateur Radio Society mobilerally. Shelley High School, Shelley, Nr.Huddersfield. l lam-5pm (open 10.30am forRAIBC)

22-30 June June Perseids meteor shower (max 26 June)25-26 June Summer 1.8MHz Contest

26 June WAB 2m/70cm Phone ContestLongleat Mobile Rally, Longleat Park, Nr.Warminster, Wilts. Opens 10am.

If you would like your event publicising in this column then send details at leasttwo months in advance of the cover date to Richard Lamont G4DYA, Ham RadioToday, 145 Charing Cross Road, London WC2H OEE.

30 May -18 June

1-16 June4-5 June

HAM RADIO TODAY MORSE COURSE offers the mosteffective route yet to your Class A amateur licence

Professionally produced for HAM RADIO TODAY by ShirleyHesketh G4HES and Ron Ray G3NCL, this advanced interactivelearning system makes use of the stereo cassette format toprovide tuition to the 12wpm test standard

With its carefully designed structure, we think that theHRT MORSE COURSE is more effective than either morseclasses or electronic morse generators

Based on TWO C-60 cassettes, it offers the controlled promptingso necessary for the initial stages of morse tuition, followed bycarefully paced test material to bring the student up to speed.Full tuition notes are provided with the cassettes

To receive your MORSE COURSE simply senda cheque or P/0 for £11.45 (inclusive of VAT and P&P) payableto Argus Specialist Publications Ltd, 145 Charing Cross Road,London WC2 OEE. Mark the envelope 'HRT MORSE COURSE'.


wescomFACTORY APPOINTED YAESU MUSEN MAIN DEALER

FT980 Full RangeFT77 Full RangeFT101ZD, Mk. 3 (real

bargain)FT230/730FT480/780FT290/790

All Accessories

Frequency Counters byYaesu

Let your Spares andService problemsbecome ours.

625 Line FSTV

BEARCAT Main Dealer

TONE Equipment

Self-support TOWERS

E.I.R.P.B.'s

TAMAYA

ROYAL

MASCOT PowerSupplies

CAR TELEPHONES

WESTERN COMMUNICATIONS (GALWAY) LTD.Unit 1, I.D.A. Cluster Development,Tuam Rbad,Galway, IRELAND

Phone: (091) 65166/65268U.K./N.1.100091 65166/65206International Dial - Int. (353I/I91/65166/65208

Telex: 28933 MHTC Ei

SELECTRONIC SERVICESTHE FINEST ANTENNAS IN THE WORLD

ARE NOW AVAILABLENo hi-fi specifications here, Just antennas that are stronger, last longer and workbetter than any other antenna available today.HF Antennas10MHz Broadside, similar to classic bobtail array (10/BDA): gain 5dBd with this wirearray at only £41.25. 14MHz Broadside. same specifications as 10/BDA, (14/BDA):E36.25.4in Quads4 Ele quad (4/4E0): gain 7dBd, £58.50; 6 Ele quad (4/6E0): gain 9dBd. £60.502m Quads4 Ele quad (2/4E0): gain 7dBd, £45.25; 8 Ele quad 12/8Eq): gain 12dBd, long yagispacing 1126 boom), £62.50All quad antennas have glass fibre booms and supports for strength and less corro-sion and less effect on performance.Had. range70cms, 6 turn 16/701-1): gain 12dBd, £4285; 12 turn (12/70H): gain 16dBd, £46.85.23cms. 6 turn 16/23H): gain 12dBd, £34.50- 12 turn 112/23H): gain 16dBd. £35.50; 20turn (20/23H): gain 17dBd. 137.50.Helix range uses glass fibre booms and comes complete with "N" plug and socket.All helix antennas have a 50 I feed impedance suitable for satellites, tropo, FMrepeaters and AN.Stacked coWnesar arrays70cms, 16 Ele (70/SC16): gain 14dBd, £45.20; 20 Ele 170/SC20): gain 16413d, £49.20.23cms, 16 Ele (23/SC16): gain 13c113d, £43.50; 20 Ele (23/SC20): gain 14.5dEid,E38.50.Continuation to be placed after stacked collinear array specifications.

COMMING SOONIDue to the massive response to our previous advertisements and many pleas for anHF minibeam "at a reasonable price that works and is not a rotatable dummy loadon 20m"! We are pleased to say that the research and development of a very highperformance minibeam is well advanced. The price will be considerably lower thanit's competitors and constructional techniques we use will ensure that they will lastfor years.Thanks for the interest you have shown. Any suggestions? Please ring (As long asthey are decent) We hope to visit most rallys and exhibitions during 1983

OVER 40 NEW ANTENNAS TO COMEThe most comprehensive range of anntenas to suit every operator and every clima-tic condition.Please enclose a stamped addressed envelope with all enquiries.

For further information contact

SELECTRONIC SERVICESUnit BT5O/55B, Perry Avonue,

Teesside Industrial Estate, Thornaby,Stockton-on-Tees, Cleveland TS17 9LN.

Tel: (0642) 760093

1

fow 9

6MTR - 2MTR - 70CMCONVERSIONS//TRANSVERTERS

FOR CB RADIOS2 MTR TRANSVERTER KIT £68.95RX UNIT KIT ONLY £38.95HARDWARE FOR ABOVE

(i.e.: case, switches, etc) £9.95COMPLETE ASSEMBLED UNIT £98.95TX UNIT ONLY FOR RX UNIT £30.006 MTR CONVERSION KIT £59.80ASSEMBLED UNIT inc. RADIO £129.9570cm TX UNIT £48.9570cm RX UNIT £45.95

Coming Soon - Repeater ShiftAbove equipment works on all models ie: AM,FM, SSB&

cwHOT LINE PROBLEM SERVICE (Technical)

Northampton (0604) 38202TUESDAY & THURSDAY 14,00 hrs. to 17.00 hrs.

ASK FOR: EVAN G8 KHC or COLLIN G3 VMUTrade enquiries by headed letter only please

Attn. G. Austin G6 NYHAll TX Kits above are sold subject to purchaser holding

current Amateur Radio TX Licence.Please allow 21 days for delivery. P + P 50p for kits

Northampton Communications Limited76 Earl Street, Northampton

Telephone: (0604) 33936

Advertising copy datesJuly issue 3rd MayAugust issue 31st MaySeptember issue 5th JulyPhone Lynn Collis on (01) 437 1002 todiscuss your copy details.

HAM RADIO TODAY the onlyamateur radio magazine that youdon't have to have a degree inelectronics to decipher.

RMTR0111Cf iTONBRIDGE)

NEW AMATEUR RADIO SPECIALIST IN KENTNow is the time to think about Antennas, Clamps, Poles

Calbe Lashings. Rotators from £40. All in stock.29 mHz LC L FM mobile Moded to cover 29.310 to 29 700 in10kc steps with 100kc shill 5 watt output. Price £5225 Watt Linear £15 95 70 Watt Linear £39.95

Send S.A.E.phone or call in for details(or see you at the Maidstone Rally.)

AZDEN 2M FM and 10M FM mobiles (NEW)WELZ "DIAMOND" antennas now in stock

FDK YAESU KENWOOD ICOM JAYBEAM B.N.O.S. DATONG DRAE EtcFortop 70cm AN RX. TX. Full range

Come in and see what we have to offer Open to 7pni Friday Closed

FINANCE AVAILABLE Wr=17334WRITE FOR DETAILS

8 TOLLGATE BUILDINGS HADLOW ROAD, TONBRIDGETelephone: Tonbridge (0732) 361850


NEW PRODUCTS

VHF/ UHFmultimodemultiband rigThe Yaesu FT726R offers FM,SSB and CW on the 50, 144 and432MHz bands, by usingseparate plug-in RF modules foreach band. An optional satelliteunit allows crossband full duplexworking, making it possible tohear your own signal comingback from an Oscar without theneed for a separate receiver.

The VFO A/B system has tenprogrammable memories, andcan be tuned in 20Hz steps onSSB/CW, or selectable steps (ona separate knob) for FM.

The basic unit, covering the144MHz band only, costs £649inc. VAT and is imported byboth SMC and AmateurElectronics UK.

10,18 & 24MHz onthe FT101 Mk. lEHarry Leeming (G3.LL) isproducing a modification kit toput all three new HF bands onthe FT101 Mk. 1E, using the CBand WWV positions, togetherwith a relay in the 21MHzposition. The kit will producefull output, but it isrecommended that power is keptto 50W or less for maximumreliability.

This modification will bedescribed in a later part of theHam Radio Today series on theFT101. We are, however, askedto point out that the kit is for thismodel only, and that it will notbe produced for any other Yaesurigs. The kit costs £15.75 inc.VAT and carriage, and isavailable from Holdings PhotoAudio Centre, Mincing Lane,Darwen Street, Blackburn,Lancs., BB2 2AF.

Dipole tuningchartThe maker of the Slinky Dipoleaerial is offering a free tuningchart to owners who want to usethe aerial on the 1CMHz band.No extra attachments arenecessary, but the maker saysthis extra information is needed.

If you want a copy of thechart then send two IRCs to theBlacksburg Group, Inc., POBox 242, Blacksburg, Virginia24060, USA.

Locator mapThe Intermedial Locatorset is anew map of Europe suppliedwith a transparent plastic rulerto enable rapid measurement ofthe distance between stations. Italso offers a quick method ofworking out QTH/QRA locators.

The map has a scale of1:3,000,000 and a claimedaccuracy of 0.5%, which iswithin contest tolerances.

It is available fromIntermedial Ltd., 3 BeechAvenue, Eastcote, Ruislip,Middlesex HA4 8MG.

Auto notch filterModel ANF from Datong is anew automatic notch filterdesigned to remove 'tune-upwhistles' and heterodyneinterference automatically. Itconnects in series with thereceiver's speaker.

The ANF has two interestingnew features - firstly ahorizontal LED bar graphdisplay to show the notchfrequency. Secondly, a speechcompander (compressor/expander) is used to ensure thefilter is operating at the optimumlevel no matter where thereceiver's volume control is set.

The ANF scans the audiorange from 270 to 3500Hz, and

BOOK: A GuideTo AmateurRadioThis new and expanded (19th)edition of the Guide seems tooffer something for every radioamateur and listener. Thebeginner will find anintroduction to amateur radio;for the listener there are tips onstarting as an SWL, with a list ofQ -codes and prefixes etc; theRAE candidate should find thetechnical explanations of manyradio topics useful; while thelicensed amateur may find thebook a useful reference.

The chapter titles are: This is

locks onto and notches out awhistle in about a second.Datong says the notch is"typically better than 40dB at3.5kHz."

The notch can also be movedmanually if desired, but withAFC to 'lock it on' once it is setwithin lath of the unwantedsignal.

The filter can also be used ina 'peak' mode to provide anarrow CW filter, with a 3dBbandwidth of 60Hz at afrequency of 800Hz.

The ANF costs £67.85 inc.VAT and is available from eitherDatong stockists or DatongElectronics Ltd., Spence Mills,Mill Lane, Bramley, Leeds LS13314E.

amateur radio; Fundamentals ofelectronics; Getting started;Amateur radio equipment;Communication receivers;Transmitters; The antenna;Workshop practice; The licenceexaminations; Operating anamateur radio station; TheRSGB and the radio amateur;International amateur radioorganisations. There are threeappendices - 1962-85 RAEsyllabus and objectives; SampleRAE questions; Safety pointers.

The book is a 160 pagepaperback, and costs £2.75 (or£3.44 by post) from the RSGB,Alma House, Cranborne Road,Potters Bar, HertfordshireEN6 3JW


T5430REVIEWTrio TS 430S Multimode HF TransceiverBy Angus McKenzie MBE, C.Eng, FIERE, G3OSS

Many readers will have used Trio's earlierTS120 and 130 SSB/CW LF and HF bandtransceivers, and will probably haveadmired them for their simplicity ofoperation coupled with good ergonomicsand reasonable performance. Despiteconstant criticism over the years, Triohave never incorporated an FM facility ontheir HF rigs before, but at last we have inthe 430 one in which an FM transmit andreceive capability is complemented byAM, upper and lower single sidebandand CW. Most unfortunately, the FMfacility together with narrow SSB and CWfilters are optional extras, at £31 to £35each, but this review sample was loanedto the magazine by Ham International,who could not supply accessories at thetime.

Facilities andErgonomicsThe TS430 is basically a 13V DC rig

which draws up to around 16A peakcurrent on transmit. It will work equallysatisfactorily as a home station with asuitable external power supply (around£100) or in the car. On receive the rigcovers from 150kHz up to 30MHz,stepping up or down in 1MHz steps orfrom one amateur band to the next,dependent on the position of a switchlabelled 'lMHz'. Two rates of tuning areprovided, with 10 or 100Hz per step, butunfortunately the 'kHz per rev' is not quiteconstant across each 1MHz band. Forexample, we measured anywherebetween 8.5 and 9.5kHz per revolution

on the smaller step position, despite Trio'sclaim in the manual that it should be10kHz. To the left of the main tuning knobis a row of five push buttons selecting LSB,USB, CW, AM and FM modes. On the lefthand side is the 13V on/off switch androckers for TX/RX, VOX controlled TX,processor on/off, ALC or currentmetering, narrow/wide IF filter (only widesupplied for review). The normal multipinTrio microphone socket is on the bottomleft, and a Trio hand mic with PTT and 'upand down' buttons was supplied with thereview sample. On the left side is also 1/4"headphone jack (plenty of volume here)and concentrically mounted rotary gaincontrols for mic and carrier insertionlevels. A fluorescent green digitalfrequency readout above the timing knobdisplays the nearest 100Hz, (or to thenearest 10Hz if an internal jumper is cut).To the left is the meter which on receive isa normal S meter but on TX reads totalcurrent of ALC. Behind another window,to the right, is the display showing theselected memory channel.

Unlike Trio's earlier models, thislatest TS430 has very many push buttonsto the right of centre, as well as somerotary switches, which can provide somemost useful facilities, but perhaps also afew that you may well never use. The mainmemory switch selects any one of eightmemory channels, insertion of anyfrequency into these requiring just thetouch of the MEMORY IN button. The 6thand 7th memory positions also serve aselect start and stop frequencies forcontinuous scanning, another buttonputting the box into the scanning mode,with an accompanying button to hold thescan. Two seperate VFOs are provided, afour -position rotary switch selectingeither of these of a criss-crossarrangement allowing you to transmit onone and receive on the other, or viceversa.

Poor documentation

Additional buttons provide facilitiesfor inserting VFO B's frequency into A,frequency lock, small or large frequencysteps, memory recall (this sets the chosenVFO to the selected memory frequencyfrom which the VFO can then move),fixed memory channel, and memory scan.Large up and down buttons shift the bandeither to the next amateur band, or to thenext 1MHz band, determined by anotherswitch. Further switches select receiverincremental tuning (the pot for this isconcentrically mounted with the 1F shiftcontrol which has a centre indent), noiseblanker, 20dB antenna attenuator andfinally a very good notch filter, the pot forwhich is concentrically mounted with asquelch control which acts on all modes.The only other controls on the front panelare concentrically mounted rotaries forRF and audio gain.

On the top of the rig are four very


small slide faders allowing adjustment ofVOX gain, VOX delay, anti -VOX andscanning speed (this is also controlled bythe 10/100Hz step switch). Theloudspeaker is mounted in the top, andwhilst this will usually be convenient, itcould be a nuisance in some positions in acar. You might have to plug in an externalspeaker. Underneath the front of the rig isa level tilt bar which lifts the front of therig up when it is resting on a table, andthis was rather nice. On the back of the rigis a heavy duty 13V power socket (leadsupplied with heavy duty fuse), 1/4" keyjack, external speaker 3.5mm jack, anS0239 RF in/output socket and a largewing nut terminal for earth connection.Three multi -pin standard Trio DIN typesockets are provided. The REMOTEsocket has seven pins with inter-connections for external ALC,loudspeaker output, a pin which shorts todeck on TX for controlling an externallinear (for example) and an external PTTline. The ACCESSORY socket had eightpins, and this can be connected toexternal equipment requiring logicinformation from the TS430 regardingthe band in use. A 12V DC voltage on TXonly id available on one of the pins, andanother pin, when grounded externally,reduces the rig's output power to about50W. Amongst the eight pins on theTRANSVERTER socket are provisions forinput/output and controlling an externaltransverter.

At this point I would like to criticiserather heavily the unhelpful manual sinceit is very difficult to find out more detailsof these pin connections and there seemsto be generally a considerable lack ofbasic information as compared withYaesu and Icom instruction books. On theback panel of the rig is an enormous heatsink, and built into this is quite a powerfulfan which comes on as and when thetemperature of the heat sink demands it.

The rig is reasonably compact, andcontains a remarkable number offacilities and has room for many options

when one considers its size and weight.(275 X 105 X 335mm abd 6.5 kg).

Subjective comments

I used the rig on SSB, and briefly onCW, over a period of two weeks on anumber of bands, and found it very easyto use, although it took some time to workout how to operate all the facilities.Transmitted audio quality frequentlyreceived favourable comments, thecompressor being liked as well. Thetransmission seemed to have a good dealof punch to it, and was very clean, alllisteners finding the transmission quitenarrow even when the processor was inuse. It was such a pity that HamInternational could not supply the FMboard because I would have liked to havetried the rig on 29.6 MHz, theinternational 10m FM calling frequency.The three new bands, in the 10, 18 and24MHz segments were not supplied'enabled', although ones supplied byLowe electronics normally have thisprovision.

Although I was concerned that thetuning rate was not exactly 10/100kHzper rev, the tuning ergonomics were verygood indeed. The scan buttons on themicrophone operated in the same way asusual, again the scanning speed beingcontrolled by the slider on the top of therig, and the step switch. Even when therig is in the 'amateur bands only' mode,rather than the general coverage 1MHzup/down steps mode, complete receivecoverage is possible by continuing tuningbelow or above the appropriate amateurband. I tuned all the way from 30MHzdown to 0Hz to check on this, not quitewearing out my finger in the process.However, the absence of a slip ringaround the finger hole, (such as on theTS830) is a pity. This makes it possible towhizz up and down very rapidly. On myscan across the frequency coverage of therig I noticed a large number of minorsprogs, and one extremely bad major one,

Rear view showing heatsink and quiet cooling fan

this check being carried out with ascreened dummy load screwed onto theaerial socket, and even with a ferrite ringclose to the set on the 13V lead. The badsprog was audibly over S9 at21.562MHz, although the meter onlyread S3 on it. The minor 'birdies' wouldnot be disturbing on lower frequencies,but you might be very slightly disturbedby one or two which were equivalent to anaudible S3 to S5 or so on the 10m band,which did not, however, register on the Smeter. The worst ones were on 28.888,and 28.921MHz.

I checked the performance audiblyon 160, 80 and 40 metres, both duringthe day and at various times in theevening, and I was impressed with theclean reproduction of DX and localstations, with no apparent cross mod orRFIM problems, the 20dB attenuatortaking good care of this when signalstrengths were way up well after dark.The RF sensitivity appeared to beadequate even on 10 metres, althoughthe IC740, for example, is slightly better.Selectivity seemed to be good, butrejection of extremely strong CW well offchannel did not seem to be as good as thaton one or two competitive rigs. TheT -notch filter was extremely good, indeedone of the best that I have measured insome time.

It is unfortunate that only one AGCspeed is available, and I felt that this wassometimes rather fast, particularly onstrong 80 metre stations. If, however, youconsider putting in the attenuator duringthe daytime on 80 metres, then even fairlystrong signals will become a little hissywith the attenuator in. Turning the RFgain control down (with attenuator out)improved the sound quality. What upsetsme a little about an AGC that acts a littletoo quickly is that voices tend to pump,and background noise in the shack,including reverberation, becomes tooaudible. I cannot remember a receiverbuilt specifically for amateur use that hadan AGC facility that I would haveregarded as too slow. I do like the optionof twiddling with the recovery speed,which is what is lacking here. I also notethat there is no apparent way of turningthe AGC off, a useful facility for CWreception sometimes.

The IF shift control, which is usefullycentre indented, and thus marking anominal centre position, was very useful.Sometimes this facility is termed'bandpass tuning', and basically altersthe position of the filter with reference towhere an injected carrier would have tobe correctly inserted to demodulate theSSB at the right pitch. It can, for example,give you the pass band from say 100Hz to2.5kHz, or from 500Hz to 2.9kHz if youprefer male voices to change sex! It canalso be used more seriously to filter out, orat least to reject more efficiently, carriersor interference just off frequency. As thenarrow SSB filter and CW filters were not


supplied, I cannot comment on theirperformance.

Memory function

Squelch action on SSB signalsoperated well, provided the signals werereasonably strong, and no problems wereexperienced with the RIT. Memorisingfrequencies and recalling them,particularly when I wanted to move theVFO either way from a memoryfrequency, operated superbly well. Thisfacility is most useful, although I cannotsee that there would be much use forpunching in the memory channel buttonand operating exactly on a memoryfrequency without the facility forVFO'ing, unless you were using the FMoption on fixed lOmetre channels.Memory 8 will be useful here, for it allowsthe memorising of separate TX and RXfrequencies for 10m repeater operation.The scanning, defined by memories 6 and7, would probably be found when youwant to scan relatively small frequencyareas continuously, but I don't expectmany would want to use the scanning forcontinuously monitoring large chunks ofspectrum other than to leave the receiverrunning on a large section of 10 or 15Mwhen the bands is closed to indicate thefirst signal that pops through after bandopening.

What cost?

The VOX control workedsatisfactorily on transmit, and the settingof gain, delay and anti -trip was verysimple. One strange feature provided bythe rig is the ability to transmit on oneband and receive on another, which Isuppose could be useful to the oddperson, but certainly not to me. I cannothelp but feel that despite the excellentgeneral ergonomics of this rig, Trio havemade it too complicated, and thus the

VOX and Scan controls mounted on top panel

price is higher than it need have been. Iwould have preferred, to have had FMplus the filter options in with the price,but some of the esoteric microprocessorfunctions perhaps available as options,but I do realise that this suggestion ratherdefeats the design idea. Let's put mysuggestion another way, then, that Trioought to release a rig with identicalspecifications, including FM, CW andSSB, but without general coveragereceive, and microprocessor functions,which overall would be regarded as aninexpensive successor to the TS130, at alower price than the present rig, which,with options, will be typically around£800. Even if the average user does notwant to use FM on 10m, and mostcertainly not on any of the lower bands, heis very likely to use a transverter with therig up to 2metres for example, and in thiscase it will be very simple to cope with

'repeaters, although you would have toeither whistle your way in, or use anexternal tone burst generator. We werenot able to try the rig into a transverterbecause of inadequate instructions, andtime, but if the transverter feed is similarto that from the TS830, the level would bevery low.

Incidentally Microwave Modulestransverters can be supplied with extrasensitivity to work with modern lowtransverter feed level outputs, althoughyou may have to modify older models.

Feelings

To sum up my own feelings for the rig,I can report that I was impressed with itsgeneral performance, but would prefersomething simpler for mobile use, but alittle more comprehensive for fixedstation use. Whilst Trio's provision of DIN

1.7; Us6 ZS -6 MAr. I kits bee* noteIL-iir_rrn

q lema tl!i,uci.Je Zi. I ocUi6 srizips, F 2me

-_s_._If_r" BrOel &Kiser

- --v)- -- lire41, ..- r.,"wwor.rrwww_

-1--- r

of AGC action.RF input

The graph shows AF outputreductions in 10dB steps.

Effectagainst

T5- 4-30 op 11 02 ---41. 3. /s 1...g: spied s-oo...../s


type sockets for many of the externalfacilities may lead to a tidier shack, Imuch prefer lots of phone sockets becauseI am, and always have been, rather afiddler, liking to try all sorts of externalcombinations in a hurry. If I can avoid thenexessity of soldering wires onto a DINsocket, at almost any cost, I will do so, butI must admit to being very prejudicedagainst them for longstanding andpersonal reasons! I used to like the largerold 'Granny -type' 8 -pin octal auxiliarysockets, but terminals or phonos are evenbetter.

I could find no actual snags in eitherthe receive or transmit side which wouldstop me recommending at least a goodlook at the rig, which is thereforecertainly worth consideration. Don'tforget to ask about accessories and aftersales service facilities before you commityourself to purchase, for this mayinfluence where you buy the rig, as well asperhaps minor differences of price.

Lab test

Having had a play with the rig forseveral days we applied some veryextensive tests to check performance inmany areas, and probably the best way tocomment on the test results is to firstfollow a received signal through fromaerial input to loudspeaker out, and thenin the same way have a look at thetransmitter results.

The RF input sensitivity varied from

10m sensivity unfortunately being one ofthe poorest, although completelyacceptable, equivalent to a noise figureof around 8dB or so. Ironically, the mostsensitive band was 14MHz, on which youdon't really need ultimate sensitivity. RFintermodulation performance waschecked with two carriers 10 and 20kHzoff channel at three levels, the twocarriers always being at the same levelrelative to each other. The first level wasthat required to develop a third order lmproduct of 12dB SINAD, whilst thesecond and third levels producedproducts reading S5 and S9 respectively.Our choice of such close in tones spacedonly 10 and 20kHz is a difficult testindeed, and my interpretation of theresults is that the TS430 comes out prettywell. The reciprocal mixing test involvedchecks on the local oscillator sidebandnoise at 20 and 100kHz off channel, andwhilst the 100kHz test result was verygood, the 20kHz one was average, somerigs being better by quite a few dB. Thisclose -in noise was quite possibly acontributory factor to the disappointingselectivity measurement for -60db,although the filter was good down toaround -40dB, and thus the shape factorwhich works out at around 2.9 is not good.During the selectivity test we heard aseries of small whistles etc. while we weremeasuring the -60dB point, which we

ParameterRX Measurements

Comment

Sens. for 12dB SINAD SSB @28.6/21.3/14.25 MHz (µV p.d).

0.17/0.14/0.12

Good/V.good/excellent

Sens. for 12dB SINAD SSB @ 7.05/3.65/1.9 MHz (1.4V p.d.)

0.17/0.14/0.14

Easily goodenough

S meter: Levels for S1/S5/S9 +20dB SSB @ 28.6 MHZ (1.4V p.d.)

1.2/1169/400 Excellent

S meter: Levels for S9 SSB @ 21.3/14.25/7.05/3.65/1.9 MHZ (kAV p.d.)

65/56/8268/59

Selectivity: SSB 3dB bandwidth/60dB bandwith (KHz)

2.316.6

Fair

Selectivity: SSB shape factor 2.9 FairRFIM: Listening at 28.6 MHz.Sending + 10 and + 20 KHz 1.6/7.1/14 GoodLevel from each for 12dB SINAD/S5/S9 product (mV p.d.)

Reciprocal mixing: Level @ + 20and + 100 KHz for 3dB degrad. in15db SINAD Signal (mV p.d.)

2.2120

Fairly good

T -notch: Max rejection of 1.4 KHzrel. 1 KHz beat (dB)

33 Excellent

T -notch: Max rejection of 1 KHz rel.1.4 KHz beat (dB)

32 Excellent

Audio output distortion @ 125mWinto 8 Q ( %)

0.5 Excellent

Audio output power in @ 10%THD 8 2 (W)

1.7 Slightlyrestrictive

Frequency accuracy of readout (Hz) within 20 V. good.Current @ 13.8 V D.C. supplyaudio gain min. (A) 1

TX Measurements CommentCW output power: 13.8 V.D.C.Supply 1.9/3.6517.05 MHz (W)

85/100/100 Good

CW 0/P power @ 14.25/21.3/28.6MHz (W)

100/90/85 V. good

SSB 0/P power @ 1.9/3.65/7.05MHz (W P.E.P.)

140/140/140

SSB 0/P power @ 14.25/21.3/28.6MHz (W P.E.P.)

150/140/140

Current drawn on full powerCW. 13.8 V supply (A)

16 Veryefficient

Current drawn on SSB, mic gainmin. (A)

2 Good

Harmonic 0/P, CW@ 1.9/3.65/7.05 MHz(2nd/3rd) (dBc)

(-60/ -58)/(-66/ -54)

/(< -68/ -49)

Good/Fairly good/Fair

Harmonic 0/P, SSB@ 14.25/21.3/28.6 MHz(2nd/3rd) (dBc)

(-64/< -53)/(-64/< -65)

/(< -65/< -65)

Fairly good/excellent/excell6nt

SSB Carrier rejection relative to fullCW power: 28.6 MHz (dB)

-62 Superb!

Transmit freq. error on CW@ 28.6 MHz (Hz)

-160 Adequate

Table of Lab test results

assume to be synthesiser modulationcomponents on the local oscillator.Selectivity was checked at two separateRF levels about 15dB apart with the sameresult. I must particularly praise theexcellent S meter, characteristic of many

Trio rigs, for its far better than usual lawfrom low to very high levels. As can beseen from the chart, there is 35dBdifference between Si and S9, S5 beingreasonably half way in dynamic rangebetween these two points. S9 however, at


Graph of audio level and10 CCIR weighted noise against RF

0

-10

-20

-30

-40

..., ..--,.....-- ---.....-- -- ...."----"" , -.."'"------ .. ".....""----'`.....

level

TRI043022/3/83

-140 -130 -120 -110 -100

Audio level

CCIR weighted noise

".

1 I L-

-90 -80 -70 -60

RF level / dBm

around 7007 right across all the amateurbands, is perhaps a little insensitive, and Iwould have preferred it to have been atthe more usual 50i.N. The T -notch filtergave a remarkable maximum notch withhardly any reduction of signal level400Hz away, which is splendid. The AGCcharacteristics can be seen very clearlyin the pen chart recording in which weknock down the RF level in 10dB stepsfrom a very high to a very low level. Notethe recovery time at the various levels,together with the fact that normal level isnot restored on lower level signals. Mycolleague, Simon G8UQX, thought of arather nice computer test to apply, inwhich computerised test equipmentmonitored the audio output level whilststepping up the RF input levelautomatically from a Marconi 2019signal generator, finally plotting theresult.

Additionally, the CCIR/ARMweighted noise was plotted with unitygain held at 2kHz, this being the audiooutput noise at the test gain controlsetting for no RF input, It can be seen thatfull audio output is reached at around2,1V input, above which the level is fairlyconstant, with just a gradual slope. Atvery low levels indeed there was slightcomputer noise breakthrough, but evenso I would ideally have preferred full levelto have been reached at a much lower RF

level, particularly for 10m where bandnoise can be so extremely low relatively.

I have already commentedfavourably on the good audio quality,and so it was not quite so surprising to seethe very low distortion measurement at125mW output from a carrier giving a1kHz beat in the product detector. Theloudspeaker was fairly sensitive, which isfortunate for the maximum availableoutput into 8 ohms was slightly limited.The only other receiver measurementwhich seems very relevant is the highcurrent drawn, which is easily suficient toflatten a car battery if the rig is left oninadvertantly for more than a day. I wouldhave thought that with modern circuitdesign the standing current could havebeen a mere fraction of what it was.

The transmitter took around 16Apeak which is very reasonable indeed,showing a high efficiency PA. The currentdrawn by the entire transmitter ontransmit, but with mic gain at minimum,was considered quite low, only doublethat of the receiver, and so the averageconsumption from a car battery will besurprisingly low, unless speechcompression is selected, which will, ofcourse, greatly increase the DC dutycycle. Frequency accuracy on transmitwas checked on CW, such that the outputfrequency measured 160Hz below thatindicated, and this is perhaps just a little

bit further out than I might haveexpected, although the receiver wasexceptionally accurate. Maximum poweroutput on CW was either at, or only verymarginally below, the legal limit, so youcertainly can't grumble, and SSB peakswere well in excess of the CW output,which is very useful. No drift problemswere noted, either on TX or RX, after awarm up period. We checked harmonicand spurious outputs on a spectrumanalyser on all bands from top band to 10meters, and must particularly praise theharmonic suppression on the latter. Theworst band was 40 meters with 3rdharmonic just a little high, but fortunatelythe harmonic was in another amateurband! SSB carrier suppression wasfantastically low, showing a very welldesigned balanced modulator. Themicrophone circuits seemed to have agood overload margin, and no problemswere noted with the transmitter, which ispraiseworthy.

Equipment used by Angus McKenzieLaboratories Ltd. for this review.

Two programmable Marconi 2019 signal generators.Marconi 995 generator, coaxial attenuators by Greenpar,Marconi, Rhode and Schwartz and Narda: hybrid transformerby Elcom: power meters by Racal and Bird, analysisequipment, including Hewlett Packard 8903 audio analyser.and MO spectrum analyser, an RF specrum analyser: HewlettPackard 8558B, a Takeda Riken eight digit frequnecy counter(four parts in 109 accuracy). a Bruel and Ktaer and HP pencharting/plotting equipment, and computer control wereappropriate was with a Hewlett Packard 9816 computer with8.2901 dual disc drive.


MON-FRI 9-5.30

24 BUCKLAND RDLEICESTER

HAMINTERNATIONAL (U.K.)

SAT 9-12.15

TEL 0533-761731TLX 341928

TS930. Superb high performance, all solidstate HF transceiver, capable of operating in theSSB, CW, FSK and AM modes, on all amateur bands(160 to 10 metres). Incorporating a generalcoverage receiver.Optional extras:-Built in A.T.U.SP 930 - Extension speaker with filters

TS430. The latest 'state of the art' HF transceiverfrom Trio-Kenwood. This new set has full amateur bandcoverage, including the three new bands and alsoincoporates a general coverage receiver. SSB, CW, AMand also FM modes are available (FM with optionalboard). Fitted with twin VFOs and all the usual filters youhave come to expect from Trio-Kenwood transceivers.Optional extras:-PS 430 Matching power supplySP 430 Matching extension speaker

FT102. Represents significant strides in theadvancement of amateur transmitter signal quality, pre-viously restricted to top of the line transmitters. For theamateur who wants a truly professional quality signal theanswer is the Yaesu FT 102.Optional extras:-FC102 Antenna tonerSP 102 Matching extension speaker

FT77. This new full feature mobile transceiver fromYaesu has 100 watts of RF power on all amateur bands from 3.5to 30 mhz (including new bands) and has FM as an option. Itsunbelievable small size and lightness coupled with its low pricewill make this set a firm favourite as a first time rig or a handysecond set to use anywhere.

FDK 750A. Offers VHF operation on FM,SSB, CW. Excellent value for the new operatorlooking for SSB facility on VHF. Also fitted withdual VFO. The set has the facility to use theoptional 'Expander 430' giving full coverage onthe 70cms band.


HAM INTERNATIONAL are no strangers to the com-munication business, having been involved on the Continent andin the UKforseveralyears.An enviable reputation has been gainedfor producing some of the finest quality communications equip-ment available. Ham International are now proud to bring you theleading names in the field of amateur communications. Yaesu,Trio-Kenwood, FDK, Daiwa and Tonna to name but a few. They areall backed by our name for service and reliability. Information isonly a phone call or SAE away. All items have full warranty and ourfully equipped workshop is on hand should any problems arise.Speedy and reliable delivery is guaranteed by Securicor at noextra cost on all orders over £250.

CICOM . COMPLETE RANGE AVAILABLE SOON

All Ham International Products and the range of amateur equip-ment we import are available from our stockists countrywide.

Redlands Amateur RadioClyst St MaryExeterDevon039-287-3040

Southdown Radio Supplies40 Terminus RoadEastbourneSussex0323-639351G6 LSO -G6 TIO

Midland Tuning30/32 Leicester RoadLoughboroughLeicestershire0533-212371G4 AMN

LIIIK1AICA119

VISA

TON N A (F9FT)144 MHz9 Element fixed £15.459 Element portable £17.459 Element crossed £28.5513 Element portable £27.2516 Element fixed £34.9517 Element fixed £34.95430 MHz19 Element £18.2519 Element crossed £31.0021 Element £26.0021 Element ATV £26.00144/430 MHz9 + 19 Element £30.00

Tridentstar LtdUnit 30Century StreetSheffieldYorkshire0742 442486G6 RIL

Enfield Lmporium281 Hartford RoadEdmontonLondon N901-804 0128G8 SYG G6LHL

Kettering HIFIStamford RoadKetteringNorthants0536 515266G6 PAK

S.M. Spain Ltd2A New RoadBromsgroveWorcestershire0527-72460G4AAL G4RUX G4LVKG8YAJ

Telecom189 London RoadNorth EndPortsmouthHampshire0705 698118G2DZT G3SED G4PYS

AVAILABLE SOONCommercial PMR Equipment

Full Range Available for Supply and InstallationWE RESERVE THE RIGHT TO ALTER OR AMEND PRICES OR SPECIFICATIONS WITHOUT NOTICE )


C5800By Peter MetcalfeG8DCZ REVIEWWhat's that I hear you say -'another 2m multimode'! YesSTANDARD COMMUNICATIONSCORP. of Japan (where else) releas-ed their answer to the 25W 2mmultimode market in England aboutfour months ago, following on fromtheir C8800 FM only model and ac-companying the CS8 portable ver-sion. Standard's attack onYaesu/Trio/Icom has reputedly beendelayed by "six months of fieldtesting to get it right". Withstatements like this abounding I amsure that you will forgive a littlescepticism. Have they got it right oris this just another standard(forgive the pun!) rig?

Documentation

The rig comes complete with avery comprehensive manual whichhas only a couple of strange transla-tion quirks (eg. in the description ofthe SSB TX amplifier, reference ismade to a "younger amplifer" - isthis some new technique I haven'theard of ?). The operating instruc-tions, especially of the synthesiserfunctions, are well laid out and easyto follow. The circuit diagrams,board layout and instructions onhow to take the rig apart are verygood and there is a particularly nicesection on TX and RX adjustments.The part of RF circuit operation is alittle sketchy, but adequate for thosewith previous knowledge of commontechniques. However, the five pagesdevoted to the PLL and digital sideof things, while being verythorough, takes some reading.

Circuit

There is nothing very earth shat-

111,

tering here; the now conventionalfinal power module (M57727A), pro-tected against high VSWR by an LCcoupling circuit sensing reflectedsignals and hence shutting downdrive to the unit. There is a doublesuperhet plus quadrature detectoron FM receive and a vari-cap tunedVCO on transmit. For SSB opera-tion, Standard employ a techniquesimilar to the Icom 1C290 forgenerating the two sidebands; ie.only one crystal is used, rather thanthe more usual two, and the dif-ferent frequencies are diode switch-ed by adding or subtracting L and Ctuned circuits. While I'm not toohappy with this method of sidebandgeneration, it seems to work fairlywell, so don't knock it! The rest ofthe SSB side is fairly straightforwardwith single conversion on receive, adouble balanced modulator, etc.

A CW side tone facility exists,

which should help with morse prac-tice, and on the display side abargraph type LED power/signalmeter is employed. One surprisingfeature is the external meter socketon the rear panel which allows oneto connect a conventional ( ICOuA)moving coil meter to supplement thepower/signal display. If, like me,you don't like LED meters, take note.The extensive use of LSI devices inthe synthesiser and control sectionalong with "a large capacity 4Kmicro -processor never before usedin a mobile transceiver" provideenough functions to keep the digitalfreak going for months.

Visual Impressions

The first thing that strikes oneabout the 5800 is just how small it is(about 51/2 " by 8" by 2"). In fact it isbarely bigger than the C58 portable


and one begins wonder how Stan-dard cram it all in. The second pointto notice is the angled front panel,which makes the display and con-trols nicely accessible, with certainprovisos, when the rig is mountedlow down in a car. However, here iswhere a problem arises, for thereare four function switches mountednear the front but on top of the unit.This means that the rig cannot bemounted flush with the dash or,when used as a base station, used ona shelf higher than eye level. A nicetouch is the fold back bench stand(how many times has this part beenlost when transferring other rigsfrom car to shack ?). The mobilemount was adequate but the reviewmodel's was a little stiff to use(perhaps it will loosen up). As men-tioned before, the main problemwith mounting is that the unit mustprotrude from any vertical surfaceand therefore the mount must be fix-ed quite a long way behind the rig'scentre of gravity. This producedconsiderable vibration of thetransceiver when using theavailable bolt holes in my vehicle,which can't be good for it.

The microphone fits neatly intothe hand but the PTT button is a lit-tle small for my liking and couldcause quite a bit of finger cramp onlong QSOs. The general impression


of the 5900 is one of a very well puttogether, neat and tidy rig (and ohso small!).

Inside

When the top and bottom panelsare removed it soon becomes ap-parent how Standard gets it all in.The lower board, which looks likepaxolin ( yeuk ), is quite frankly amess. There is no real attempt atmicro -miniature components and sothe inside is obviously very crowd-ed. However, what really spoils it isthe profusion of wires linking partsof the same board and coming fromthe panel controls. OK, so it's asmall rig with nowhere to hide thesewires, as in different models, butsurely they could have made moreextensive use of ribbon cables orflexible PCB's (as in the IC2E). Arather better plan would have beento spend more time designing thePCB itself to eliminate the need forall these flying leads. I feel that ifmodification or servicing is needed,it would be very difficult on thisboard. Not surprisingly, the speakeris a mere 2" in diameter, however, itdoes a remarkable job consideringit's size but I would still recommedan external device wherever possi-ble (10% distortion in a noisy vehi-cle is rather difficult to listen to for

long periods).The top board looks more ac-

ceptable; agreed it is still verycrowded, but more plug/sockets areused and there is an attempt to routecables round the sides. This meansthat at least you can see where youare. Being dedicated to the PLL anddigital circuitry, this board looksmore professional (fibreglass,shadow masked etc.). The inclusionof a small piggy -back board con-taining the toneburst circuitry in-dicates the European version of therig.

The final board making up thetransceiver is the power module andits associated drive circuitry. This ismounted at the back in a metalenclosure and with a little dismantl-ing should be fairly easy to get at.

Generally, this is not the type ofrig to play around with unless youhave experience of fitting quarts in-to pint pots.

Operating Impressions

With such a small front panel,the controls are necessarily packedin tight. This presents a few pro-blems when operating; for instance,the mode switch is very awkward,being concentric with the RIT con-trol. The squelch control is evenworse and has to be adjusted fromunderneath, if one is not to alter thevolume setting (it was very difficultto use when mobile). A little moreroom between volume/squelch andthe main tuning dial control wouldhave helped here. While on the sub-ject of mobile operation, again wehave a rig with a profusion of similarlooking, multi -function buttonswhich require very little travel tooperate them. This makes the rigconfusing, not to say dangerous, touse in the car. The microphone plugobscures many of the push buttonswhen the set is mounted to the left ofthe operator and I feel that, for truemobile use, many of the features ofthis rig must remain unused; cer-tainly any change of mode is risky.The five digit, green, fluorescentdisplay in rather dim and difficult toread on a sunny day (yes, there wasone in December!). Also there is anannoying multiplexing flicker pre-sent.

Generally, I was not terribly im-pressed by the layout of the controlsfrom a mobile point of view. As abase station or /P, it is a different

65

matter for then one can put up with afew hardships and it is the functionsthat matter. Indeed, the 5800 hassome very nice facilities but alsosome very confusing ones. The sizeof the frequency step depends onthe setting of three controls in addi-tion to the mode. The exact effect is aniterative process of trial and error . Aswell as this, there is also available,from one of the keyboard buttons,1MHz (FM) and 100 kHz (SSB/CW)up/down steps. I found this featurerather useful, especially as the righas the annoying quirk of coming upon 14EiMHz when first switched on.A useful addition, especially formobile work, is the inclusion of afrequency lock button whichdisables most of the keyboard andthe up/down microphone switch,but does not affect the "Call" but-

ton. This "Call" facility seems arather pointless addition, especiallyas the sax) has auto-toneburst. Infact, being positioned near one ofthe most used keyboard buttons(Clear), it is a positive disadvantageand can cause some embarassingmoments.

Listening on FM showed that the5800 is quite a sensitive rig althoughthe rather 'toppy' audio made it dif-ficult to pick out weak signals fromthe general noise level and madeworking 'DX' on FM a bit of a strainon the ears. The two position RFgain switch, "DX/LOC", seemed tobehave in a particularly odd fashionwith strong S9 signals being reduc-ed to around S2 but weaker signals(eg. Si) hardly being attenuated atall. The usefullness of this switchwas therefore nullified as in-

OISPLV

KL'BOAL

ROTALTSW

DIGFTS[RIVE

SEGMENTSCP VE

0 06,PA57C

OLO4TA 76

SCAMOO

01_05TC4 05.13

TX

ULO3To 76

47010 SW

SDK_P T

CH o/6,G

OPT MODE

/IL .330140.68

FAST

0,20c

uP/ DOWMIC JAC

-I MODE S

u D

MIC

0101

P- COM

TX.5.6.00

SO L

SAM00011TA/612OP

terference could still occur betweenlocal and distant stations on thesame frequency. The usual problemassociated with led signal strengthmeters was experienced ie. weak,but Q5, signals caused no indicationon the display. However, the exter-nal meter socket could be used bythose who like to see something hap-pening. (It seems psychologicallyreassuring to have some indicationof just how weak a signal is!)

SSB listening also showed upthe sensitive front end of the 58Wand the audio in this mode was quitepleasant to listen to. The RIT controlgives ± 1.2KHz shift and surpris-ingly this also operates in the FMmode. Possibly due to its sensitivity,the rig was very susceptible to staticnoise and the noise blanker, whilenot being particularly effective,

TRACKING

BE

Oi.MC.40110

!To 82ATRIA S

PLL BLOCK

RX OUT

TX OUT

PTT TONE BURST TONE

0 SC OUT PUT SW 10003 000s 1

MCI4093 2SC136,11II

FM AEG +El

00 MOD

5513 DET08114040701-3R

SSB OF AMP

0E02250842F

45C DET

_4i ORO° 0091

S58 SM.

0E119 0091

r- Tis7 -I

OPOI90M455130

SSB SOL AMP

0001 59 -TI1M45580 -

RESET SO

01.10

25C 336F

RESET SR

01.092 SC 536E

RESET S

OLO8Ma 522 IC AMP

FM CH STEP

.4/250 0.

.200/20%

F NALrto AUOIO Too-COM

COM Re

POPE SW0503T1_

496C

BACKUPS.

fosocosoaoo

254,6*R2SC 368Z4ALL

Rog

J 0510

ME TER Reg

SW

2t:945

SW RogTo PA.

O5113756

BSSB S

05.325[945

FM OX RegTo RX

FM SW R 9%I'LL 00

05 52506 3

FM TX Rog SW TX RogTO TX PLL To TX

254673 2506'3I 05210517

USB/CW RXTo RX

0022506 3

0501NJAMS3135

1/2181

CW TX 550 RogTO TX SW Reg Ton, SSB RX

a

052925067 3

0514083 756

0S3204673

T /R SW

053425C945

SUB CARRIRE SW

OTO, OTO4ISISS5

_L

10 69930ov106993.042LOB 7015MmxFM 1.57000MH z

MIC AMP

SUB CARRIRE

OTOS

2SC 460I131

FM RE

0T062SC9450

AMP

ÒNE BURS' TO TONE BURS'


needed to be on all the time. A se-cond problem noticed, concerningthis aspect, was the excessively long"hang" time on the AGC. Themanual does, however, indicate therelevant R/C components andperhaps a useful mod would be toreduce this time constant to preventhuge chunks of the QSO being miss-ed.

Reports received from FMtransmission were of quite goodaudio quality and modulation levelbut the large dynamic range of therig, while giving excellent signalslocally, was not too good at cuttingthrough the noise for DX work. Thiswas particularly noticeable whenused by a female operator soperhaps some tailoring is called for.(I wonder why manufacturershaven't woken up to the fact that

IF AMP

OROS

3SK, 0 tGR

there are many more YL operatorsnowadays!) Obviously due to thephysical size of the rig, and henceits correspondingly small heatsink,I found that the set became very hotindeed during long FM QSOs andso Standard's warning about moun-ting the rig in a well ventilated posi-tion be taken seriously if disaster isnot to follow!

Repeaters

Repeater operation shows uptwo very awkward features. Firstly,the toneburst is activatedautomatically if the PTT is pressed,released and then pressed again inquick succession. Now while thiscould be useful for mobile opera-

AGC

2820C9450

AMP

US REG

OP062052

2?cR940

0P03254711

DOT

480.0.04.05

151555

55B SCAN

OR2225C945

NB

0907MPS4,3

NO AMP

NB AGC

ONOB259450

NB AMP

FM enSOL

METER AMP ME TER AMP

0180 04022SK3041.,

FM METER AMP FM

MIXDE,

AMP AMP

OR 5C33510

0 TO7 01082SC46018H 2SC460,BI

BUFF MPOTiO

2SKIRIGR

SOL

AF AMP

OBIT25CIB42

A

IR; Am, BP;

NB

090125I 5356

AMP

TER AMP OF r

003200330A 99

AF VOL.AMP SISAL

4-

BM0109

9048 MI -314

CW S

013125C945

TRACKING

0 II25K161GR1 - I OPF

MIX

CITi6250161581

SIDE TONE OSC

0006250450

I

.1OT 17

35110158

CM SW

201C ,35 15

Bit SW0114CZ,2

ACC AMP

SW T5REG 6

0722210536

0 19

ZSC 2053

ACC DE I

0120,0T2._0499 .

SW.13

0822RA, %R.

0E1022552538

FAINAL

08061/5,121A

APC Sw API. AMP

LOW

tion, the fact that it cannot be swit-ched off forsimplexFM work, coupl-ed with the small PTT button, cancause some odd tones to appearwhen not wanted. Also, as withmany rigs, the tone is rather long,but this could easily be modified.Secondly, the three positionS/R1/R2 switch takes some gettingused to. "S" is the normal TX/RX onthe displayed frequency. "Rl" gives- 600 kHz repeater shift from thedisplayed frequency which meansthat switching from simplex torepeater operation is time consum-ing, as one has to switch to RI andthen retune to the desired repeateroutput. The "R2" setting gives truereverse repeater operation and TX is600kHz up from the display frequen-cy. As the set covers the full144-148MHz range and there is noout of band switching above145.999, there could be problems ifyou don't keep your wits about you!Out of band protection below144MHz takes the form of a ratherblunt "OFF" message on the display(one or two suggestions were for-thcoming as to a more pointeddisplay here!). Strangely, this doesnot protect one from transmitting(surely a little extra logic could havebeen employed). A good point isthat "listen on input" is instantlyrealiseable by switching from "R 1"to either "S" or "R2" and that thetoneburst and call facilities aredefeated on SSB/CW operation.However, the repeater shift is notswitched out on sideband and as thisswitch is one of those on top of therig, it can easily be forgotten (redfaces all round!). Odd repeatershifts are not catered for by the 5800and so using it with a transvertercould cause problems.

Reports from SSB contacts in-dicatd a very nice "full, rich sound"and, apart from confusion over fre-quency step size, the 5800 was plea-sant to operate in this mode. Being aregular horizontal FM/SSBoperator, I found the absence of asecond VFO troublesome whenmoving from sideband up to FM fre-quencies, but the 100kHz up/downfunction, with practice, came inuseful here. Yet again, Standardadopt the strange habit of having25/1W settings on FM but only 25Won SSB, which could cause pro-blems when using linears requiringeg. 10W of drive; I'm sure amodification will arise.


STANDARD C5800 LABORATORY TEST RESULTS

Test frequencies 145.000MHz (FM mode) 144300 (SSB/CW)Power supply voltage 13.8V unless otherwise statedDeviation 3kHz (5kHz for selectivity measurements)

RECEIVER SECTION

FM sensitivity for 12dB SINAD (measured as PD) 0 18u V

SSB sensitivity for 12dB SINAD 0.15 uV

FM selectivity 12.5kHz either side of test frequency -64dB/61dB

FM selectivity 25kHz either side of test frequency 72dB/73dB

RF intermodulation performance, two generators25khz and 50kHz away from RX frequency for 12dBSINAD on IM product, FM mode 0 7/0.4mV PD

SSB selectivity at -6dB and -60dB 2.5kHz/5.6kHz bandwidth

RF intermodulation (SSB +50kHz, +100kHz) for S5IM product (equivalent to 4.5uV PD) 7 9mV

S Meter calibration characteristic FM modeS1/S5/S9/S9+20dB 0 35/2.0/3.2/4.5uV

S Meter calibration characteristic SSB modeS1/S5/S9/59+20dB 2 2/4.5/7.9/14.1uV

Generator frequency shift for best SINAD at 145MHz 0 8kHz

TRANSMITTER SECTION

FM power output (high low setting) 23.7W/0.9W

FM power output (12V supply) 19.8W/0.9W

Maximum current consumption 5A

2nd and 3rd order harmonic products , full powerFM mode --63dB/-70dB re. carrier power

PEP SSB output power 35W PEPAs above but 12V 30W PEP

Dial calibration accuracy -200Hz

FM deviation (peak transient/average peak) 6.4/5.2kHz

1750Hz toneburst accuracy +20Hz

AF THD at 125mW audio output 3.2%

Audio power output, 8ohms at 10% THD 2 . 9W

Misuse survival. Infinite VSWR forl Os total(Ss open circuit, 5s short circuit) Satisfactory

OUR CONCLUSIONS

I had an opportunity to play around withthe Standard C5800 before its despatch tothe testing house and can confirm that itis a desirable little box.lt compares equitablywith the 2m multimodes from Yaesu(FT -480R) Trio (9130) and Icom (IC -290E).At f359 the price is on par and, with 35Wof SSB on tap, the C5800 is the most power-ful 2m multimode that we have tested to

date. Furthermore, the receiver sensitivityis just a nose ahead of the competitionalthough I feel that the difference here is

not significant.There is of course a minus side. The strong

signal handling characteristics were notoutstanding and the Trio 9130 still comesout best in this respect. The shortfall in res-pect of the C5800 would not be noticed inday to day operation of the set and wouldonly have real importance when operating

The review sample was loaned by LeeElectronics Ltd of Edgware Road, London.

The engineering section of the review wascarried out at Angus McKenzie Laboratories

OUR OBSERVATIONS

At least as good as every other 2 m multi -mode that we have tested. Top class

Once again, top of the pile although intheory, there is still room for improvement

Adequate but not stunning

As above

Dynamic range 90 dB. pretty good

OK, but doesn't compare with a decent HFtransceiver

Dynamic range 6 5 dB in SSB mode. Notgood but better than some

This S meter characteristic is a joke. Stickto audio reporting

The joke is wearing a bit thin

Satisfactory

Good

Excellent.Excellent

Excellent

A bit on the high side

A bit off. Might not access some boxes

a contest from a crowded hilltop, or if an-other amateur sets up a station next door toyou.

The SSB operating bandwidth is anotherdetraction but unfortunately seems to befairly general with VHF gear. Either themanufacturer cuts corners by specifyinga cheap filter unit or, as is more likely,the manufacturer still has not come to gripswith synthesiser design producing machineswith noise sidehands all over the place.However, this must be put into perspect-ive. Thankfully, the VHF bands are not ascrowded as the HF ones and any shortfallwill not he noticed in day to day operation.

G4)ST


PLL BLOCK

L

0103 TC5082PL

REF

OSC 1/1024

_L_= 10 24MHz

W N'600-799E 14.600-999

TC50131AP- 1 LPF

0102

LN

LPF

0101TC9.22P

AMP AMP

0107 id 01062SC46012 2SC4601B1

0L02

TM51025NULL

UN LOCKOFT

016025A 7331R

0/A

A 0550NJ M2902

BUFF

ACO

0203

TRACKING

BUFF MIX

256125141-4'0204

200535181

W 191.22-193 21 MHZ

E 191 22-.195 21MHz

JUN LOCK SW

1H25291645210125009611510

X BUFF

02502SK24i0R

B

BPF AMP

02513SK101GR

AMP

025225C2349

0105 01042SC535181 250535113

0421200530481

LOCALOSC 3T IMES

1E 61 7400MHz-T-

D/A 0/A

0550NJM29021bikHNJAV9021ar.-

Dia

0550NJ M29021,1

ROLL OFF0301

NJ 1.405580I/2D

LIMIT TER0301

41- NJP4455813I/ 20

LPF 0253-441---0 RX OUT

-4-i4-0 TX OUT

0254

000 37 IMES 13PF

0402252:2131BI-4\

= 19 3033MHz

SHIFT0501

NJM45585/2 a

57 92000- 57 9100114Hz

TX RX S

05062SC94510

RIO 5 R1T SW

0510 05112SC94540 250945101

FM Reg

USEI/CW Roy

LSO Reg

RIO

0\5 RI T SW

W 133 3-.135 29999

MHz

E 133 3-.13729999

MHz

O FM MOO

0 TONE

Memories andSynthesiser Functions

The 5800 has ten memories inall, with five for each of FM andSSB. I found the display very goodwhen entering memories, a flashingled tells you if that memory is empty,and one is reminded of the mode byother leds. The only awkward part ofmemory entry and recall is that onehas to step sequentially through allfive memories to get to number five.The manual states that if the "RCL"(recall memory) button is keptdepressed, then the unit stepsthrough all the memories sequen-tially. However, I found this not bethe case. A multi -way switch would.have been nicer, but there is hardlyroom for that on the panel! The loud"bleep" which accompanies manyfunction settings is useful for mobileoperation especially. A very nicetouch is that if one recalls amemory, it is possible to tune fromthat frequency using the dial.

Memory and frequency scann-ing on the 5800 are very versatilewith the option of scanning all oc-cupied memories of the selectedmode or complete sections of theband (1MHz blocks for FM andeither 1MHz or 100KHz blocks forSSB/CW). The type of scanningdepends on the position of a three-way switch on the top panel in-dicating when, if at all, the rig is tostop scanning. The options are tostop on Busy, Vacant or Free chan-nels. This last option means that itdoesn't stop but continues thepreselected scan taking no accountof any signals present. The scanspeed in this mode is slower than inany other mode and gives one ampletime to listen for a familiar voice onthe band! The "Fast" button doublesthe speed of the scan and whenscanning the memories for a "Busy"channel with this button depressed,it zooms through the frequencies atquite a rate.

Generally, the synthesiser func-tions on the 5800 are very useful andpractice one can set up the rig to

fend for itself quite happily, whileone gets on with something useful(like working out all the mods. re-quired to bring the set up to an idealstandard!).

Perhaps because of the use ofLSI devices, the quoted currentconsumption on this rig is surpris-ingly low with 3.7A for 25W TX and450mA for receive standby. This be-ing the case, it should help give anextra hour or two of /P operation;always a useful point.

Summary

In conclusion, although thereare many minor irritations presentin the 5800, and it is hardly the bestchoice for mobile use, I feel that it isa nice rig to use containing somevery useful functions and generallygood RF design. There seem to bemany modifications that one couldthink of and here problems couldarise due to the internal layout. I

wouldn't say that Standard have gotit completely "right" but it's close.


AVON

6 GOLF CLUBLANE,

SALTFORD,BRISTOL

Tel: 02217 2402Open Toes Sat 9am 9pm

Close Mondays

5773siosTo,

Radio CommunicationsAmateur P M R Marne

12 IL PENIOVWFLL ROAD BRISTOL. RS5 OTJ

CAMBRIDGESHIRE

WISBECH AMATEURRADIO

The Chase, Chapel Road, WisbechTelephone: 0945 581099

Open. Mon -Sat 9-6. ICOM, HALBARAERIALS, REVCO AERIALS, SALES - SERVICEACCESS - VISA, PART EXCHANGE WELCOME

CHESHIRE

58-62 Lower Hillgate, StockportTeL 061-480 4872 Open: Mon 8 Wed 941late nights Tue.& Fri 9-7pm. Sat 9-5.30.

Closed ThursYaesu, Sommerkamp, Diawa, Jaybeam, Kenpro,

Weitz, Datong

HAMPSHIRE

FARNBOROUGHCOMMUNICATIONS97 Osborne Rd, North Camp.

Farnborough. Tel. 0252-518009Open: 6 days 10-6

Yaesu, icorn, FDKs, Mosley aerials, Jaybeams,G Whips

189 London Rd., North End,Portsmouth. Tel (0705) 682145

Stockist of YAESU, TRIO, TONNA, ICOM,FDK, JAYBEAM

Barclaycard & Access. HP & PX welcome

FOR YOUR BUSINESS TO BEINCLUDED, CALL

SHEILA OR JAN ON01-437 1002

KENT

ThaVir.dc.ICEICCAT

143 Recular Rd., Herne BayTel. 02273-63859

Open: Mon -Fri 9-5.30, Sat 9-12.30(Closed for lunch 1-2)

LANCASHIRE

BETA 0.1111ACOMM

231 Chorley Rd., Swinton,Greater Manchester.Tel: 061-793-1010

Open: 7 days a week.TRIO, YAESU, ICOM, GWHIP.

AERIAL BOOSTERSTrebles incoming weak signal

B11 - for VHF/FM radio; B45 - for UHFtelevision

Next to the set fitting. SAE for leaflets. E7Electronic Mail Order Ltd,

62 Bridge Street, Ramsbottom, Lancs BLO9AGH

THE YAESU EXPERTS CONSULTGALLSales Dems & Repairs + Mod Kits

HOLDINGS LTD:t9-41 Mincing La, BlackburnTel: (0254) 59595

CLOSED THURSDAYS

ISHERWOODSELECTRONICSHover Street, Blackburn

Tel. 0254-57616Open: Mon -Fri 9.5, Sat 10-1

An Aladdin's Cave of Components

LEICESTERSHIRE

26-28 BRAUNSTON GATE,LEICESTER. TEL: 553293

Open: Mon -Sat 9.00am to 5.30pm

LONDON

THE CENTRE10 MERTON PARK PARADE,

KINGSTON ROAD, SW19Tel: 01-543 5150

Open: 6 days 9am-6pm llate night Weds until 8pm)

DAVEMICK

The Enfield Emporium

G8SYGG6LHL

AMATEUR RADIOHours. Mon to Sat 9-6, Late Friday 9-8. Sun morn 10-1

281 Hertford Road, Edmonton N9Tel: 01-804 0128

THE MARINE ELECTRONIC CO LTD1-4 Swan Mead, SE1 4SY. Tel 01-237 3474

Open: Mon -Fri 10am-5pmCommunications Equipment for the

Professional and EnthusiastCallers by appointment only

W. MIDLANDSDEWSBURY ELECTRONICS +

176 Lower High St, STOURBRIDGETel: (0384) 390063

Open: 9.30-5.15. Closed Thurs. & Sun.ACCESS/BARCLAYCARD

HEWARD'S HOMESTORES LTD. (Est. 1963)822/4 Kingstanding Rd., Birmingham

B44 9RT. Tel. 021-354 2083G4RJM with 38 years in The Radio Trade

Ham Equipment urgently wanted!Open: Mon -Sat 9-6

r Please include my business details in the next available issue of Ham Radio Today

Business Name:#111111

.11/

Address:

016°Tel. No.Open Hrs:

Contact (Office Use Only):Post to: Emporium Guide, Ham Radio Today, 145 Charing Cross Rd., London WC2H OEE

L-

70

J.10111111110110 J


NORFOLK

36 Cattle Market Street

NORWICH(0603)667189

NOTTINGHAMSHIRER.A.S. (NOTTINGHAM)

P Owen G8UUS3 FARNDON GREEN; WOLLATON PARK

NOTTINGHAM: TEL 0602 280267Oven Tues-Fn 10-5.30.Sat 9-5

YASSU: FM* ICON: SOIMINENILUM: TOONAMUM: WELL ANTEMIAS 8 OWN OVA H.F.

SCOTLAND

AXDON32 Atholl Street, Perth

Tel. 0738-23753. Open: 6 daysICOm, TONA, TONG RSGB Books. Maps &

log books. Full range of componentsMail order available - send for price list

LOOKING FOR TRANSEIVERS!AERIALS! AMATEUR RADIOACCESSORIES! TRY YOURLOCAL LISTED STOCKIST

JAYCEE ELECTRONICSJOHN GM3OPW "'"ut&r-20 Woodside Way, Glenrothes Fife KY7 5DF

Tel: 0592 758982Open Toes -Sat 9-5

Quality secondhand equipment in stock Fun range of TRIOgoodies. Jaybeam - Microwave Nodules - LAR

SUSSEXSOLI

FiPilEK140 TERMINUS RD . °pp.EASTBOURNE RailwayTel: 10323) 639351 Stn.)

Open: Mon -Sat 10-6 (Closed Tues)Stockists of: Yaesu, Trio, Tonna, FDK etc +secondhand and ex -Government equipment in

stock

MAIL ORDER PROTECTION SCHEMEIf you order goods from Mail Order Advertisers in thismagazine and pay by post in advance of delivery, thispublication will consider you for compensation if theadvertiser should become insolvent or bankrupt,provided:

1. You have not received the goods or had your moneyreturned; and

2 You write to the publisher of this publication explain-ing the position not earlier than 28 days from the dayyou sent your order and not later than 2 months fromthat day.

Please do not wait until the last moment to inform us.When you write, we will tell you how to make your claimand what evidence of payment is required.We guarantee to meet claims from readers made inaccordance with the above procedure as soon aspossible after the advertiser has been declared bankruptor insolvent to a limit of £1,800 per annum for any oneadvertiser, so affected, and up to £5,400 p.a. in respect ofall insolvent advertisers. Claims may be paid for higheramounts, or when the above procedures have not beencomplied with, at the discretion of this publication, butwe do not guarantee to do so in view of the need to setsome limit to this commitment and to learn qu'ickly ofreader's difficulties.This guarantee covers only advance payment sent indirect response to an advertisement in this magazine(not, for example, payments made in response to cata-logues, etc, received as a result of answering such

advertisements):

CLASSIFIED ADVERTISEMENTS ARE EXCLUDED.

TYNE Et WEAR

RLY TIYONICS Pia Aftl"El I iCs6M1

Dorler Stock

129 Chillingham Rd, Newcastle-upon-TyneTel: 0632 761002

Open: rites -Sat 10am-6pm

YORKSHIRE4 Cross Church St, Huddersfield Tel:

Open 6 days 9.5.30.0404 20774Closed Weds. Thurs 9am-8pm

G4MH Mini Beam4tways a good selection of new & 2nd na,, .. 'nent in stock'

Amateur Radio Shop

decovsn TIE wauD W3TM AmATERRADK:Si

LEEDS 452657..PIKKISSIONAL

TRIO ICOM YAESUSILOS ANIATE, P0130 Mal 00.0(11/1.St.veCf DLO! OPEN YON -F.,SO(InIFNPOPO ,AFNvolOOLf (DS 'I. 'An,. I 10. - SpaBRITISH MADE 11E3. LAR PRODUCTS

HAM RADIO TODAY - MAYADVERTISERS INDEX

Allweld EngineeringAmateurRadioExchangeAmtronicsAmcommArrowElectronicsC.Q. CentreDewsburyElectronicsFortop Ltd.Ham InternationalIntermedialH. LextonMobile Figures CoMyers ElectronicsNorthamptonCommunicatio021 Radio&ElectricalPMComponentsPM ElectronicsPolemarkLtd.RATECS.M.C.SelectronicsWPOCommunicationsWesternConimunications

12IFC

55,72IBC36234132

62/6323

87273

n 55OBC

5233222

34/35552255


HAM RADIO TODAY CLASSIFIEDLineage:30p per word (minimum 15 words)Semi Display (min 2 cms)1- 3 insertions £5.50 per cm6-11 insertions £5.00 per cm12+ insertions £4.50 per cmAll advertisements in this section must be prepaid.Advertisements are accepted subject to the terms andconditions printed on the advertisement rate card (available on request)

EQUIPMENTRTTV CREED 444 As New.595 hours use from new. STSterminal unit dual machineautostat. Professionally built.The pair £175. Might split. Trio2200 GX Nicads charger £80o.n.o. DAIWA LNA 1001 autoATV as new in box £110 o.n.o.G65YZ-QTH R-(Cornwall)(020)888 738.

AMATEUR RADIO EQUIPMENTToggle switches, cables, test metersetc. Send s.a.e for price list to M.J.Seaward, 7 St. Olafs Road StrattonNr. Bude, Cornwall EX23 9AF Tel(0288 4179).

ALUMIUM DIPOLES - 4m, 6m, 10m,£7.95 ea.. 12m, 15m, 17m, 20m, £9.95 ea.,CABLES - RG58 19p/m, RG8 49p/m,30031-T.F. 12p/m., CONNECTORS -PL259/6 49p, PL259/9 49p SWRMETERS - 5W H.F. £5.95, 100W H.F.£15.95, 10W 2m/70cm £19.95, P.S.U. -13.8v 3/5A £14.95. 5/7A £16.95. HAL BARAERIALS. Barclaycard/Access. All pricesinclude P&P and VAT. Electronic Facil-ities, 3 High Street. Sandy, Beds.(07671 81494

ONE SUMMER CAMPFT/2772D. Mint condition£595 and one Kenwood 2400portable 2 metre £165.Gobowen CB Centre, TheCross Gobowen, Shropshire.Tel: 0691-661397.

IK-1 CMOS/VMOS Iambic keyer. An electronic morse keyer with sidetone andinternal PP3 battery. VMOS technology allows our keyer to key the rigs other

keyers cannot! Positive or negative versions.£19.95 & 50p P&P

MPA-2 144MHz Masthead preamplifier. Our advance design with selectivehelical filter can switch up to 500W pep.Ideal for DX or Contest WorkCmos morse practice oscillatorPiptone/Roger bleepK bleep £6.00 & 25p p&pOur CM1000 HF Transceiver is currently under development. Send SAE or phone

for information on this and our other products.Please note 12 months guarantee on all our products.

CHRIS MOULDING RADIO SERVICES, 276 HULTON LANE, BOLTON,BL3 4LE 0204-651348

£33.50 & 50p p&p£6.50 & 50p p&p£4.50 & 25p p&p

ELECTRONIC BARGAINSUPPLIES

VERSATILE BEN H POWER 'UPPLY UNITSContains high quality transformer made to exacting specificationsgiving one 40v output and one 20-0-20v output. All outputs 3amps.D.C. input 110/250v c/s. Bridge rectification. Contained on metalchassis with robust compact case size 7"x51/2 "x41/2". Easily modifiedto give 40 or 60v output. Makes an ideal variable power supply. Nor-mally costs around £60.00. OUR PRICE AS NEW with circuits £8.50.Carr. £3. 2 untis for £20 carr. free.AMPLIVOX ULTRA LIGHTWEIGHT TRANSDUCER EARPHONES.Impedence 300ohms. Made to fit inside protective and crash helmetsor can be used as pillow earphones. A new £4 per pair. PP £1. 2 pairs£8. Post free. 4 pairs £15. Post free.MINIATURE TRANSISTORISED BFO UNIT. EnablesyoutoreceiveC.W. and S.S.B. transmission. Fully transistorised (turntable). Verycompact. fits anywhere. Single hole fixing. Brand new with fittinginstructions. £6.95. PP. 50p.GENUINE AFV TANK HEADSETS AND MIKE. £3.50 per pair. PP.£1.50. 2 pairs 1.50 post free. All headphones fitted with ex -ministryplug. Standard jack plugs available 25p each. 2 for 40p. Headphoneextension sockets available at 25p each. 2 for 40p. Impedance °Hirsttwo items 600ohms. All headphones in .00d condition.

THE GOVERNMENT SURPLUSWIRELESS EQUIPMENT HANDBOOK

Gives detailed information and circuit diagrams for British andAmerican Government Surplus receivers, transmitters, test equip-ment etc. Also suggested modification details and improvements forsurplus equipment. Incorporated is a surplus/commercial crossreferenced valve ONLY £7.50. PP. £1.50. No VAT on books.PYE POCKET PHONE PFI DATA AND INSTRUCTIONS. Contains,circuits, layouts, operating and modification details for amateur useetc. £1.50 post free.GENUINE TRANSFORMER BARGAIN. Brand new Westool 15v. 1amp transformers. Mains input. £2.75 each. PP. 75p. Or 2 for £5.50.PP. £1.HIGH QUALITY 17-0-17 TRANSFORMER made to exacting specifi-cations. 3 ampoutput. Mains input. £2.95. PP. 60p. Two for MOO postfree.GENUINE EX -GOVT COLLAPSIBLE AERIALS. A fully adjustablehighly efficient whip aerial in 5 sections. Length 1'2 metres. Closed300mm. Copper plated sections. As used on EX -Govt manpacks.Brand new in make3rs boxes. £2.50 each. PP. 75p. 2 for £5 postfree.HAVE YOU SEEN THE GREEN CAT. 1,000's of new components,radio, electronic, audio and unbelievably low prices. Send 50p forcatalogue. (Refundable on purchase).PLEASE ADD 15% VAT to all orders including carriage and PP.

AllDept HR 1112/ 14 Harper Street Leeds LS2 ILATel (0532) 452045 Retail premises at above address(opposite Corals) 9 to 5 Mon to Sat Sunday 1010 1 byappointment Govt. Surplus Items always in stock.

=Ring for information on series

bookings/discounts

lv

01-437 1002EXT 204Send your requirements to:Jo James,ASP Ltd.,145 Charing Cross Road,London WC2H OEF

AERIAL PARTS14 swg Hard Drawn Copper AerialWire 20p per m (post 2'/s p per ml:Strong PVC covered stranded AerialWire 6p per m (post 2'/2p per m):300 ohm Twin Ribbon Feeder 1 2pper m (post 2p per m); 75 ohm TwinFeeder 18p per m (post 2p per m);UR43 50 ohm COAX 20p per(post3p per m); UR70 50 ohm COAX 20pper m (post 3p per m); UR67 50 ohmLOW LOSS COAX 50p per m (post

5p per m)W.H.WEST LAKE, G8MWWClawton, Holsworthy, Devon.

B.N.O.S.

Manufacturers of PowerSupply Units and V.H.F

linear amplifiers.B.N.O.S. Electronics

Dept. HRTC, Greenarbour,Duton Hill, Gt. Dunmow,

Essex CM6 3PTTel: (037 184) 767

TRANSMITTERS RECEIVERS ETC.All frequencies, well known makes.ICOM, FDK, AZDEN, LOWE, STAN-DARD, etc. etc. Power supplies, wave -meters, test meters, frequency count-ers, Welz SWR and Power meters. Mic-rowave modules, linear amps. RTTYetc. Quality equipment for am-ateur,PMR and Marine use. Aerials, Co -axcable, plugs. See our advert underEmporium Guide. £1000 INSTANT HPavailable and ACCESS -Booth Hold-ings Bath, 6 Golf Club Lane, SaltfordBristol BS183AA. Tel (02217) 2402.Staff includes G3N XLW, G3X0D,G8DPH.

ANYTHING TOSELL?

Then sell it quicklyand cheaply

Phone ASP Classified01-437-1002 ext. 204

Special prices on surplus equipmentEddystone Receivers 77OR(/11F) 770U(Lllirl 1.133 Model 830 £170 730/45001e14..31.MHz in 5 bands. ALI in excellent Carr £15.Murphy MOD Receivers £65. Carr 1.15Pye Bantams High band AM untested less xtal and batt f22With xtal and batt tested £30 Avo Valve Tester £25New 28 Range Digital Multimeters £40.25. PCR Receivers LW /MW /SWwith built-in mains PSU tested £45 Untested less PSU £25.Advanced E2 Signal Generators 100KHz- 100MHz £40 P&P £3 Taylor 67ASignal Generators 100KHz-240MHz £45. P&P £312ft Whip Aerials £4, P&P £1.50. Various: Single and Double BeamOscilloscopes, Signal Generators, Valve Testers, Output Meters etc, instockSurplus Circuits new book containing many circuits and notes on varioussurplus receivers, transceivers, etc £6.50 Sned 50p for fully illustratedcatalogue (includes £l voucher). Over 500 sets in stock Avos, amateur rigswanted for cash.

Weirmead Limited,129 St Albans Rd, Watford, Her ts lA1011RA

Telephone: Watford 49456. Access Visa cards welcome

KEEP YOUR HANDS ON THE WHEELwith the . iii-neice/ safety microphone system

Pre -amp + Timer + Electret Condenser MicNo extra connections to transceiver tila ne

L,16Send for a leaflet

.74(Fully inckniye)

R &A \SUDRON LTDTel (0532) Ferndale, Colliers Lane737120/435711 Shadwell, Leeds LS17 8LP

VALVES

VALVES VALVES VALVESThe following valves in matched pairs 6JS6/C 6KD6, 6JB6/A6HF5 6146A 6146B YES the 6JS6/C is Japanese and works inthe FT101. Most amateur radio valves including difficult toobtain EX STOCK. Quotations without obligation. If we don'tstock your type we may be able to import for you. Please enquire.Remember, over 200 types EX STOCK. Phone for assistance retypes suitable for your equipment. USA and Jap manufacture ofpopular types available.Don't Delay Phone Today 04575 611 4 D4A2M. Free Postagewith this advertisement.Wilson Peel Cottage, Lees Road, Mossley, Tameside, Man-chester.


ANTENNA

AMTRONICSNew amateur radio specialists inKent. Jaybeam Tonna: Welz "Dia-mond". Hoxin. Antennas now in stock.Finance available. Access, Visa. Writefor details. Tollgate Buildings. HadlowRoad, Tonbridge. Telephone: Ton -bridge (0732) 361850

RESTRICTED SPACE HF QTH's.

A G2DYM UNI-POLEWILL BE YOUR ANSWER, TX

OR SWLDATA SHEETS LARGE SAE,

AERIAL GUIDE 75pCallers WelcomeTel: 03986-215

G2DYM,UPLOWMAN

TIVERTON, DEVON

Ant Products, All SaintsIndustrial Estate, BaghillLane, Pontefract, West York-shire. Telephone 0977

700949AMATEUR ANTENNA

Silver 70-70 cms 16 dbdGain Beam £31.95Tiger LY6 9 dbd2 Meter Beam £12.95Tiger LY8 11 dbd2 Meter Beam £19.50Tiger LY10 14 dbd'2 Meter Beam £32.95

TWO YEAR GUARANTEE ON ABOVEZL12 Mk 2 13 dbd

'Gain Beam Antenna £32.95ZL8 Mk 2 9 dbd

'Gain 5'-7" Long Boom £19.95ALL ABOVE HAVE STAINLESS STEEL

PARASITIC ELEMENTSNorcone 512 Wide Band

'Discone Antenna £25.95

((Extra)Delivery

(Extra) £4.00-Send cheque or money order today. made!payable to Ant Products or write enclosing

S.A.E. for full details.

30 FOOT STEEL and alloy maststillover £100 For details P.O. Box16, Redruth, Cornwall.

ANTENNES TONNA (F9FT)YOUR NUMBER ONE CHOICE FOR 6m, 2m, 70, 24 8 23cm ANTENNAS

50MHz5 element'144MHz4 element9 element fixed9 element portable9 element crossed'13 element portable'NEW 17 element fixed436MHz19 element19 element crossed'21 element 432MHz21 element ATV144/436MHzOscar Special9 Er 19 element'

1250MHz or 1296MHz23 element' £25.9131b)4 x 23 element antennas - power splitter - stackingframe f140.001e1Telescopic Portable Masts4 x I m E15.961e1 3 x 2m f19.15I814 .2m £28.751a1ANDREW HELIAX LDF4-50 COAXIAL CABLEAttenuation per 100ft 144MHz - 0.8dB435MHz - 1.6dB 1296MHz - 2.9dB£3.20 per metrele) 'N' type connectors for LDF4-50male or female 00.35

MICROWAVE MODULES - ROTATORS -COAXIAL CABLES ETC.POWER SPLITTERS AVAILABLE FOR 2. OR 4

f30.051a1 ANTENNAS

£31.74181

(13.011e)(15.441e)E17.461a)£28.521e11727.211e)f35.191e)

£18.141e)f30.051e)£26.0010E26.001a)

'Denotes 500 ONLY - all others 500 OR 750PLEASE ADD CARRIAGE AS SHOWN le) £4.00; (bI £1.80.

Terms:Cash with order. ACCESS - VISA - telephone your card number.ALL PRICESINCLUDE VAT AT 15%. For full specification of our range send 30p for Catalogue.

Callers welcome, but by telephone appointment only please.

RAN DAM ELECTRONICS (H)12 CONDUIT ROAD, ABINGDON, OXON OX14 108. Tel: 102351 230030 124 hours)

SPIDERLIGHT 4,

Rot proof ABS latticed masts and antennas. No metal parts exceptconnectors on antennas.Masts: up to 15ft. single stage £182; 20ft. two stage £303; 30ft.

three stage £385; 40ft. four stage £495. All ready construc-ted, not kit

Antennas: VHF 14 element £42; UHF 24 element £43. Uniquedesign allows horizontal, vertical or circular polarisation.

All masts will take standard types of antenna. Also black box mastand antenna service, we supply and erect, just plug in Tx/ Rx. Askfor quote.Prices inc. VAT at 15% and carriage, mainland only. C.W.O., Visaor Access. Just telephone anytime.

The Mobile Figures Co Ltd, Unit 7, SawmillIndustrial Estate, Alnwick. Tel: 0665 711005

G2BAR HAM BAND AERIALS62 METRES HF. BEAMS GAMMA MATCH5/FD Element ,, £1 1.78 10 METRES8/FD 8 Element £14.58 2Element Array £40.501/JP 'J' Pole £11.78 3Element Array £52.0070 CMS 15 METRES7/FD 7Element £11.20 2Element Array £46.5011/FD 11 Element 814.58 3Element Array £61.00

Prices inc. VAT & Postage - Road Line Extras H/F Beams

YAESU MUSEN STOCKISTHF and VHF ranges available & readily demonstrated

Microwave Modules - Toyo - Hansen - SWR BridgesFor descriptive leaflets send 30p stamps

12 14 PENNYWELL ROAD BRISTOL BS5 OTJTelephone. Bristol (0272) 557732

AERIAL GEARWe supply the best aerial equipment in the UK. Specialists in TV,FM equipment, DXing. Aerial masts, components, amplifiers,filters.'One-off' aerials made toyour needs eg UOSAT,Airband,etc. SAEleaflets.Hirschmann R0250 rotor, control consul £43.50; SL100 align-ment bearing for same £16.50; TVI? In -line bandstop filters for27,144 or 453M HZ,fits in TV feeder-+30dB stop, 1 dB elsewhere,£9.50 (45 filters listed!): Revco Discone £24.95.All prices incl. VAT/post. Catalogue 54p. Barclaycard/Accesswelcome.The best costs less at

South West Aerial Systems,10 Old Boundary Road. Shaftesbury. Dorset SP7 8ND.

Componentsto sell?

Phone ASPClassified

01-437-1002ext. 204

COURSES

COURSES - RADIO AMATEURSEXAMINATION City & Guilds.Pass this important examinationand obtain your licence, with anyRRC Home Study Course, Fordetails of this and other courses(GCE, professional examination,etc.) write or phone - THE RAPIDRESULTS COLLEGE, Dept. JX1,Tuition House, London SW194DS.Tel: 10-947 7272 (9am-5pm) oruse our 24 hr Recordacall Service:01-946 1102 quoting Dept. JX2.

MORSE CODE REPARATIONReceiving: Cassette A: 1 -12wpm for amateur radio examina-tion. Cassette B: 12-25 wpm forprofessional examination pre-paration. Each cassette is typeC90. Price each cassette (in-cluding booklets) £4.75. Send-ing: Morse key with separatebattery (PP3)- driven solid-stateoscillator and sound transducerproduces clear tone for sendingpractice. Price of key with oscil-lator £10.50. Prices include pos-tage etc. Europe only. MH Elec.tronics (Dept. H), 12, LongshoreWay, Milton. Portsmouth PO48LS.

LEQ MORSE CODELESSONS

This renowned 7xC90 cas-sette course comprisingapprox. 10 hours of instruc-tion from basics to 14 wpmand sample Morse tests forHam licence including notesonly £24.50. Additional HamMorse procedure C60 cas-sette £3.50. Send cash withorder or S.A.E. for more de-tails to: LEOtronics, Pre-ference House, Old MarketPlace, King Street, Knuts-ford, Cheshire WA16 6E0.

NEW!! Scientifically preparedfive-day courses to get youthrough the R.A.E. examina-tion: 01-346-8597.

MORSE CODE CASSETES C908-13 WPM in groups of five. Plainlanguage 3 minutes sectionsnumbers exam pieces etc. withreadback inclusive price £3.20S.M. Spain (Bromsgrove) Ltd, 2New Road, Bromsgrove Worcs.Phone 72460.

CARDS, STICKERS, BADGES

ENGRAVED LAPEL BADGESLapel badges with electrically weldedsafety clip, most colours available.Example Club Badge. club name, per-sonal name, callsign, with or withoutRSGB logo - 1 to 10 badges 85peach. 10 and above 80p each inc P&P.Please use block capitals for all orders,cash with order, orders dispatched byreturn first class post.Club Secretaries please send for sample

DARFIELD ENGRAVING SERVICES39 Cliff Road, Darfield, Barnsley,

S. Yorks S73 9HRTel: Barnsley (0226) 752106

CALL SIGN LABEL BADGESprofessionally engraved, by re-turn of post. £1.50 cash withorder (state name & call sign)Aylmer -Kelly - H, 2 PickwickRoad, CORSHAM, Wilts., SN139 BJ.

LISTENER & OSL CARDSQuality printing on Coloured andWhite Gloss Card at competitveprices. SAE for samples S.M.Tatham "Woodside", OrchardWay, Fontwell, Arundell, WestSussex.

WANTED

WANTEDAll types of marine. electronic, radioand radar equipment. The MarineElectronic Co. Ltd, 1-4 Swan Mead.London SE1 4SY. Tel: 01-237-3474Open Mon -Fn. 10am-5pm. Callers byappointment only

SECOND HAND Yaesu and allgood transceivers wanted Guil-ford CB 0483 574434.

HAM EQUIPMENT URGENT-LY WANTED! Heward's HomeStores Ltd (est. 1963). 822/4Kingstanding Rd., BirminghamB44 9RT. Tel: 021-354-2083.G4RJM.

KITS

RTTY TERMINAL UNITS forcomputer interface P.C.Bs, wiredmodules, boxed units, modernactive filter Design excellent forBBC Computer S.A.E. J. Melvin0632 843028


APPOINTMENTS FOR SALE Save money on drawer sets with

DesignEngineers

Satellite CommunicationsMajor expansion of our SpaCe Division has creatednumerous opportunities for engineers to be involved insome of the most technologically challenging work onmeteorological and communications satellitesQualified Hardware and Software Design Engineers ofvarious levels of experience are required for posts whichvary from Engineering Manager/Group Leader tomembership of a Design Team Disciplines include

Spacecraft SystemsCommunications Systems

Microwave Systems and EquipmentRadar and Signal Processing

Electronic Circuit DesignMechanical, Thermal and Dynamics Design

Power Supplies Switch -ModeSalaries and benefits will reflect the importance weattach to the positions and relocation assistance isavailable if requiredPlease write or telephone stating your qualifi-cations, recent experience and area of interest toJack Burnie, Marconi Space 8. Defence SystemsLimited, Browns Lane, The Airport, Portsmouth,Hants. Tel (07051 674019 Ref: BL 34.(All posts are open to men and women)

Marconi )""Space & Defence Symms

AVOID WASTED RESPONSETo fill your vacancy cost effectively and

quickly. Reach over 60,000 people in theradio field.

To place your recruitment advertisement.01-437-1002ext 204 now.

elMle MINIM

YASEV FT207 2 metre hand-held manual charger. 2 Nicads£100. R107 receiver £20. Wok-ing 62809 (work no.) attnPeter.

ORIC BBC programs RTTV£7.50. Morse tutor £4.50.Distance £3.50. S.A.E. Listcheques to Vomek Software,11 The Dell, Stevenage,Herts.

2 METER SSB transceiversfrom £138. Full range includingTrio, Yaesu Asden etc. creditfacilities. Guilford CB 0483

574434.

the BITSABOX

12 &awe,wideoerdlooardbench mefor yourbd. andpieces

Drawer .w140 x 50

370,0

YI Soo* Rood Landon El?P,op P E Dcmcloon

PERSONAL CALLERS & TRADE ENQUIRIES WELCOME

THE INSTANT WAY TOADVERTISE USEDEQUIPMENT!!

If you are Selling/Wanting amateur Radio EquipmentLIST -A -RIG is a must.

Send large s.a.e. for current list and full details FREE!!

SEND TODAY TO LIST -A -RIG (HR) 65, CECIL AVENUE,HORNCHURCH. ESSEX, RM11 2NA

C3111CC2 Eliec t _Tonics R.A.O.T.A

TOP QUALITY USED AMATEUR TEL: HORNCHURCHRADIO EQUIPMENT BOUGHT,SOLD EXCHANGED. 55733 (6-0pm)

PUBLICATIONS

WORLDWIDE MARITIMERADIO STATION LIST DX/UK. Approx 1000 frequencies£2.75 BJP publications. 64Bryn Awelon, Mold, Clwyd.

AVIATION FREQUENCIESThroughout Europe

As used by BA and other majorAirlines

384 Pages £5.75 inc p&pOrder by phone. Access and Visa

welcome.Other lists available.

AOS (HRT) West LondonBuilding,

White Waltham Aerodrome,Maidenhead SL6 3NJTel: (0628 82) 5362

COMPONENTS

COPPER AERIAL WIRE 14 swghard drawn, 70' coils, £5.50, 140'£8.90 inc postage. T.M.P. Elec-tronic Supplies, Unit 27, PinfoldWorkshops, Pinfold Lane, Buc-kley, Clwyd, N. Wales SH7 3PLTelephone: Buckley (0244)549563

AERIAL WIRE Hard Drawn Cop-per 140ft 14SWG £6.90, 50 met-res 16 SWG £5.90 includingpostage. S.M. Tatham, 1 OrchardWay Fontwell, Arundell, WestSussex.

BF981 VHF LOW NOISEMOSFETS. Limited quantityavailable. Brand new. £1 each.Tel: 0304 853089 evenings.

HAM RADIO TODAYCLASSIFIED ADVERTISEMENT - ORDER FORM

Rates of charge: 30p per word per issue (minimum of 15 words). Box Nos. £2.50p per issueand post to HAM RADIO TODAY, CLASSIFIED DEPT.,

1

Advertise nationally in these Columns to over 60,000 readers foronly 30p per word (minimum charge 15 words). Simply print yourmessage In the coupon and send with your cheque or postal ordermade payable to Argus Specialist Publications Ltd. to:CLASSIFIED DEPT. HAM RADIO TODAY145 Charing Cross Rd, London WC2H OEE.Tel. 01437 1002Please indicate classification required.

NameAddress

Tsl.No.IDay)IPlease place my advert in Ham Radio Today for 0 months. Please indicate number of insertions required.

OR Debit my Access/Barclaycard(Delete as necessary)

I

I

I

I

I

J74 HAM RADIO TODAY JUNE 1983

MAIL ORDERCALL MAIL ORDER 01-422 9585 (3 lines)

TET ANTENNASAX210N 10 ale. yagi for 2m crossed 74.95HBIOF2T 2 ale. 10m mono band beam 51.50HBI OF3T 3 ale. 10m mono band beam 74.95HBI5F2T 2 eta 15n, mono band beam 60.66HBI5F3T 3 ele. 15m mono band beam 93.46HBI5M2SP VP mini size 15m 2 ale. 69.50HB15M2SP VP mini size 15m 3 ele. 102.30HB34D 4 ele. to band beam 10/15/20rn 222.90HB33SP 3 ele.tn band beam 10/15/20m 192.50HB35C To band array 10/15/20m 283.95H6357 5 ele. 10/15/20m 278.50MV3BH Vertical for 10/15/20m 37.99MV4BH Vertical for 10/15/20/40m 48.90MV5BH Vertical for 10/15/20/40/80m 63.95MLM Loop antenna 10/15/40/80m 105.60S022 Phased 2 ele. swiss quad 2m 58.95SOY06 6 ale. quay 2m 45.75SOY08 8 ale. quagi 2m 52.75HB2105 10 ele. dual driven yagi 2m 47.991E214 14 ale. long yagi 2m 74.40SSL720 9 x 2 ale. (18) slot fed 70cm 77.20HB23SP 2 ele. to band beam 10/15/20m 135.60SSL318 9 x 2 ale. 118) slot fed 2m 144.79TPH2 Phasing harness 2m 17.25OYUI0 10 ale. gimp. 70cm 67.9050007 70cm 2 ale. phased swiss quad 66.99S010 Swiss quad 10m 97.50S015 Swiss quad 15m 106.90The prices above Include V.A.T. and delivery.

YAESU RANGEFT1 General coverage transceiver POAFT102 Price on applicationFV101Z Remote vlo POAFANT101 Fab for 101 series POAFT902DM 9 band AM/FM transceiver POAF19020 9 band transceiver POAFC902 9 band atu. swr/pwr etc. POAFIV90IR Transverter fitted 2m module POA430N 70cm module for above POA144TV 2m module for transverter POA707V 4m module for transverter POASPOT External speaker POAEl..21002 9 band 1200W linear POAFT77 New HF Mobile POAFP77 Power Supply Unit POAFC77 Antenna Tuner Unit POAFRG7700 SSB/AM/FM recvr. dig readout POAMEM7700 Memory unit for above PO*ConvertersFRV7700A 118-150MHz POAFRV7700B 60-60MHz 8 118-150MHz POAFRV7700C 140.170MHz POAFRV7700D 70-80MHz & 118.150MHz POA

FRT7700 Receiver aenal tuner POAFF5 LF filter for above POAFT480R 2m all -mode transceiver POAFP80A 230V AC power supply POAFT8OR 70cm all -mode transceiver POAFT290R 2m all -mode portable POANCI IC AC charger POACSC -1 Carrying Case POAMMB-11 Mobile mounting bracket POAFT208R 2m synthesized portable FM POANC9C AC charger POAFT708R 70cm hand-held POAYPI50Z 150W dummy load power meter POAYH55 Standard 8 ohm headphones POAYH77 Lightweight headphones POAOTR24D World Ham clock POAYM34 600/50k ohm base m lc 8 pin plug POAYM35 600 ohm hand mic up/down 8 pin p. POAYM36 600 ohm as above (no up/down) POAYE7A 600 ohm hand mic. 4 pin plug PO*

TONO and TASCOFull range ex. stock. Call 01-422 9585 13 lines) NOW.

ANTENNA SWITCHESSA 450 one in two out SO 239 9.99SA 450N one in two out N Connectors 13.20All Items VAT and carriage paid.

The prices above Include V.A.T. end delivery.

OPPOSITE SOUTH HARROWTUBE STATION ON THEPICCADILLY LINE

VHF - UHF LINEAR AMPSTONO 2M50W 2m 50w linear I/P 3watts 69.00TONO 2M100W 2m 100w linear/preamp

VP 10w 129.00TONO MR150 2m 130-150watts linear

amp/preamp 169.00MML 144/30LS 2m linear amp 3w in

30w out 69.95MML 144/100LS 2m linear amp 10w in

100w out 139.95MML 432/70 70cms linear amp 3w in

20w out 85.00MML 432/100 70cms linear amp lOw in

100w out 228.65AL INCO 230 2m linear amp 1-3w in

30w out 39.00MIRAGE 2m linear amp 10w in

80-100w out 120.75MIRAGE B 1016 2m linear amp 10w in

160w out 189.75YAESU 2010 to match FT290R 10w out 54.00YAESU 2050 to match FT 290R 50w out 115.00YAESU 7010 to match FT 790 I Ow out 90.00TOKYO HP 2m linear amp 1-3w inHL32V 30w out 53.50TOKYO HP 2m linear amp with preampHL82V and output meter 2 in 12 out

35 in 85 out 144.50TOKYO HP 2m linear amp DreamyHL 1 80V output meter 10 in 160 out 242.00The prices above include V.A.T. and delivery.

ROTATORSKR 400RC constant readout round meter

11/2.21/2 masts 114.90KR 800RC 200Kg 11/2-21/2 masts 163.30KR 500 180' elevation rotor 114-21/2 masts 112.10AR 40 medium duty HF 90.85CD 45 constant readout - armature

breaks 81/2sq.ft. ant 136.85HAM IV constant readout wedge solenoid

breaks 15sq.ft. 258.7072X THE BIG DADDY up to 30sq.d.

of ant. 327.75RO 250 Light duty suitable most VHF/UHF 45.00SKYKING medium duty HF constantSU 4000 readout 83.00The prices above include V.A.T. end delivery.

YAESU HF MOBILE ANTENNAESRSL 3.5 3.5Mhz resonator and whip 12.50RSL 70 7.0Mhz resonator and whip 12.10RSL 14.0 14.0Mhz resonator and whip 11.70RSL 21.0 21.0Mhz resonator and whip 11.60RSL 28.0 28.0Mhz resonator and whip 11.40RSL 2A Mast for above 5.25RSM 2 Gutter mount -feeder and

connector 11.50

The prices above include V.A.T. and delivery.

MORSE KEYSHK 707 Straight Manual keyer 14.50BK 100 Semi -automatic mechanical bug 22.99MK 702 Manual keyer on marble base 26.99MK 702 Manipulator 22.99MK 705 Squeeze paddle on marble base 21.72EKM I A Morse code practice oscillator 10.50The prices above include V.A.T. end delivery.

DESK MICROPHONESSHUPE 444D Dua. ,mpec/ance 49.50S.-/U0E 526T Mk ii Power M/c/o66one 59.50ADONIS 0U502 Comp/4431, Mic I 0/1. 39.0.3ADONIS AM601 Compress/on ....c Meter I 01P 48.00ADONIS AM/302 Cornor434.0n 3.3.4 -/- Meier 3 0/P wooThe prices above include V.A.T. end delivery.

INFORMATIONFOR TRIO R1000 OWNERS

We don't have to tell you how good the receiver is -neither do we have to tell it is missing one essentialfeature- FM! No longedAmcomm have specially deigneda unit to complete your listening pleasure. It is small andwill fit with minimal effort and time. It comes with reallysimple and concise instructions which can be read andused by the most non -technical users. The FM1000 isavailable now post freeetC15.99 inc. VAT from AMCOMM.

Amcomm Services,194, Northolt Road, South Harrow,Middlesex HAO 2EN.Telephone: 01-422 9585. Telex: 24263

( SHOWROOM OPENING HOURS ) ASK FOR DETAILSTUESDAY TO SATURDAY OF ATTRACTIVE LOW DEPOSIT

10.00 - 6.00 CONTINUOUS EASY TERMS

All items advertised in stockat time of going to press.

AMTECHNew Improved range - Made In EnglandAmtech 300111- To suit all coaxial and random wireantennas - 160-10 metres. 300w PEP.£49.95 including VAT end carriage.Amtech 2008- Random wire ATU rated 200w PEP,will tune virtually any wire over 180-10 metres -excellent for base, mobile or temporary 0TH.£32.95 including VAT and carriage.Amtech 100111- Miniature mobile impedance match,ideal for that difficult matching when mobile - rated180w PIP and has switched positions.£17.95 including VAT and carriageAmtech FM 1000 - suitable for conversion of TrioR 1000, see details on lower part of page£15.99 including VAT and carriage.

ANTENNA PARTS AND KITSincludes the world's finest traps - REYCO. which areguaranteed for five years no condenser used - noblow up possible. Precision moulded coil forms withstainless hardware - aluminium irridite finish - fullywaterproofed and suitable for wire, vertical and beamantennas. rated at 2.5Kw and weigh only 4oz per trap- available for 7Mhz (KW40) 14 Mhz IKW20) 21 Mhz(1(W15) and 28 Mhz (KW10).E16.99 including VAT and carriageThe BALUN - The Unadille W2AU is famous becauseits the best, same rating as the traps and has a built-inlightning arrestor - available 1.1 and 4:1 - get it rightfirst time with W2AU Belun - guaranteed for five years.£16.99 including VAT and carriage.THE KITS - AMCOMM 40- 1 pair KW 40 Traps.1 PL 259. 1 W2AU Balun. 1 pair insulators and ofcourse 120ft soft drawn copper wire - coverage 80.10metres (Includes 10 Mhz). Full instructions included.£41.50 including VAT and carriage.AMCOMM 20- 1 pair KW 20 Traps, 1 W2AU Belun,L PL259. 1 pair insulators and 65ft soft drawn copperwire - coverage 40-10 metres. full instructions included.E37.50 including VAT and carriage.AMCOMM 35- 1 pair KW 10 Traps. I pair KW 15 Traps.

1 Pi. 259. I W2AU Salon, 1 pair of insulators and 30ftsoft drawn copper wire - coverage 20m, 15m and 10m.Full instructions included.E47.50 including VAT and carriage.New WARC Traps- KW 12. KW 17 and KW 30 nowavailable from stock.Et 8.99 including VAT and carriage.

ICOM HF EQUIPMENTC 720A Gen. Coverage Tcvr.C 720A Gen. Coverage Tcvr. with FMC 730 Base/Mobile 8 band HF TcvrC 740 WARC 9 Band HF Tcvr. P.O.A.C PS 15 For above rigsC 2KL Linear Amp. inc PSUC AT 500 Auto antenna couplerC R70 Gen. Coverage Receiver

ICOM VHF- UHF EQUIPMENTC 251E 2m base multimodeC 25E 2m 25w mobileC 290E 2m multimode lOwC 290H 2m multimode 25w P.O.A.C 2E 2m handheldC 4E 70cms handheld

L I soft cases

Full rang. of accessories available from tock.

SWR-POWER METERSHANSEN FS 710 1.8 - 60Mhz - 2Kw PEPwith time constant 89.70HANSEN FS 801 1.8 - 60Mhz - 2Kw PEP 51.35HANSEN FS 5E 3.5 - 150Mhz 3 rangesto 1Kw (HF) 37.20HANSEN SWR 50B 3.5 to 150Mhz 1Kw IHF) 26.45YAESU VS 200 2001 to 1Kw 52.90YAESU VS 2000 PEP meter 2Kw 69.75RF 2000 twin meter 3.5 - 150Mhz 2Kw 18.60YM1X twin meter 3.5 - 150Mhz 12 and 120w 15.50

V.A.T. Included, but add 75p for carriage.

E SO. E

(1

Amcomm Services,Freepost, Harrow, Middlesex HA2 OBR.

)1

Please send meI at enclosed cheque/P.O. for 1

1

or charge my VISA/ACCESSII No

I NameAddress

t HR6post code )

A new ramie of antennas -/for those vihomust haveonly the best.

Ask for themat your localamateur radioshop

DEALER

Documents

L,11 fs'A iTL-A3 fiction of VHF/VHF aerial systems€¦ · KR250 Kenpro Lightweight 1-1r mast 46.00 1370 Morse Tutor 950213 Colorotor (Med. VHF) 56.60 AD270 Indoor Active Filter (inc