25
DONT MISS FREE MAP WITH CALL SIGNS NEXT WEEK Vol. 11, No. 33 SATURDAY, JANUARY 20, 1923 Next Week SPECIAL BROAD- CASTING NUMBER (See page 64} nttd Electrics Price 3d. A r ,LM p> f AN AMATEUR'S (Mr. W. S. HUTTON'S) FOUR-VALVE SET THAT HAS GIVEN EXCELLENT RESULTS THIS WEEK'S FEATURES What Causes Fading ? More About Vario-couplers Loud-speaker for Eight Shillings Repairing a Low-frequency Transformer Notes for the Novice—Some Simple Defini- tions High-frequency Amplifiers A Variable Grid-leak 5LP: An Amateur-equipped Transmitting and Receiving Station Cigar-box Valve Panels A Simple Series-parallel Device Loose-coupler with Dead-end Switch Re-radiation Radiograms, Information Bureau. Corre- spondence. Broadcast Telephony, etc. THERE IS A SPECIAL ANNOUNCEMENT ON PAGE 64 r I DON'T MISS FREE MAP WITH GALL SIGNS NEXT WEEK Next Week SPECIAL BROAD- CASTING NUMBER (See page 64} f nnd Electrics Vol. II, No. 33 SATURDAY, JANUARY 20, l£f23 frice 3d. m d y m . I'M - AN AMATEUR'S (Mr. W. S, HUTTON'S), FOUR-VALVE SET THAT HAS GIVEN EXCELLENT RESULTS THIS WEEKS FEATURES What Cau.«es Fading ? , More About Vano-couplers Loud-speaker for Eight Shillings Repairing a Low-frequency Transformer Notes for the Novice—Some Simpk Defini- tions High-frequency Amplifiers A Variable Grid-leak 5 L P; An An ateur-equipped .Transmitting and Receiving Station Cigar-box Valve Panels A Simple Series-parallel Device Loose-coupler with Dead-end Switch Re-radiation Radiograms, Information Bureau. Corre- spondence. Broadcast Telephony, etc. THERE IS A SPECIAL ANNOUNCEMENT ON PaGE 64

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Page 1: Amateur Wireless Magazine, Weekly, Sat 20th January 1923...Amateur Wireless Magazine, Weekly, Sat 20th January 1923. DONT MISS FREE MAP WITH CALL SIGNS NEXT WEEK Vol. 11, No. 33 SATURDAY,No

DONT MISS FREE MAP WITH CALL SIGNS NEXT WEEK

Vol. 11, No. 33 SATURDAY, JANUARY 20, 1923

Next Week

SPECIAL

BROAD-

CASTING

NUMBER (See page 64}

nttd Electrics

Price 3d.

A

r,LM p>

f

AN AMATEUR'S (Mr. W. S. HUTTON'S) FOUR-VALVE SET THAT HAS GIVEN EXCELLENT RESULTS

THIS WEEK'S FEATURES

What Causes Fading ? More About Vario-couplers Loud-speaker for Eight Shillings Repairing a Low-frequency Transformer Notes for the Novice—Some Simple Defini-

tions High-frequency Amplifiers A Variable Grid-leak

5LP: An Amateur-equipped Transmitting and Receiving Station

Cigar-box Valve Panels A Simple Series-parallel Device Loose-coupler with Dead-end Switch Re-radiation Radiograms, Information Bureau. Corre-

spondence. Broadcast Telephony, etc.

THERE IS A SPECIAL ANNOUNCEMENT ON PAGE 64

r I DON'T MISS FREE MAP WITH GALL SIGNS NEXT WEEK

Next Week

SPECIAL

BROAD-

CASTING

NUMBER (See page 64}

f

nnd Electrics

Vol. II, No. 33 SATURDAY, JANUARY 20, l£f23 frice 3d.

m

d y m .

■ I'M -

AN AMATEUR'S (Mr. W. S, HUTTON'S), FOUR-VALVE SET THAT HAS GIVEN EXCELLENT RESULTS

THIS WEEKS FEATURES

What Cau.«es Fading ? , More About Vano-couplers Loud-speaker for Eight Shillings Repairing a Low-frequency Transformer Notes for the Novice—Some Simpk Defini-

tions High-frequency Amplifiers A Variable Grid-leak

5 L P; An An ateur-equipped .Transmitting and Receiving Station

Cigar-box Valve Panels A Simple Series-parallel Device Loose-coupler with Dead-end Switch Re-radiation Radiograms, Information Bureau. Corre-

spondence. Broadcast Telephony, etc.

THERE IS A SPECIAL ANNOUNCEMENT ON PaGE 64

Page 2: Amateur Wireless Magazine, Weekly, Sat 20th January 1923...Amateur Wireless Magazine, Weekly, Sat 20th January 1923. DONT MISS FREE MAP WITH CALL SIGNS NEXT WEEK Vol. 11, No. 33 SATURDAY,No

^tnateur ^WL«5

E CONOMIC LECTRI

m

9^.

CRYSTAL DETECTORS, 5/6

r Write > To-day for 40-

Pag/e WIRELESS A-lst Post Free

[4d.

HEAD RECEIVERS From 12/6

250 Illus- trations. -m® ENCLOSED CRYSTAL

DETECTOR, 12/6

INDUCTANCES 50/-

(3M

VALVE HOLDERS, 1/9

Head Office 10, FITZROY SQUARE, LONDON, W.I.

Showrooms: 303, EUSTON ROAD, N.W.f,

Telephone: MUSEUM 1055

Branch Showrooms & Works TWICKENHAM

BEGINNER'S GUIDE TO WIRELESS Fxplains in plain, everyday language, everything beginners ■wish to know about "Wireless Telegraphy.-J

HOW TO ERECT, CONNECT, AND MAKE all the apparatus required for reception of telephony or morse, and full instructions and diagrams lor making coils, tuners, and complete valve and crystal sets. 112 pages, price 1/-. post free. SAXON RADIO CO. (^t), South Shore, BLACKPOOL

32 page Catalogue of Wireless Apparatus, 2d. post free.

HERE'S REAL RADIO SERVICE 99

Telephones, best French, adjustable earpieces, 4,000 ohms ... 451 Os- Od. « m j. „ „ . 8,000 ohms ... £1 2s. od- „ genuine " Brunet " steel Headbands, 4,000 ohms ... £1 2s. 6d single earpiece with cords and handle, 4,000 ohms 11s. Od' mounted on Ebonite, ball socket joint ... 2s. 6d'

Is. 6d. and 2s. 0d' 38. 6d* lOd* 2s. Od" IS. 3d- per doz. 5s. Od' 29. 0d" ... 6d. and Gd- 4s. Od- Telephone, 2s. Od. Is. Cd, 6d.

Crystal Detectors, Hertzlte Crystals Wound Inductance, 12 in. x 4 in. wound with 22 enamel wire Brass Rod and Slider, complete with plunger (13 in. rod) Rheostat, remarkable value ... ' ... Valve Holders, each 9d. with screwed legs and nuts Batteries, 4—5 volts, suitable for H.T. ... Phosphor Bronze Aerial Wire, 1/18, 100 ft. coils ... Insulators, Reel 2, Largo Egg, 6d.; Shell Enamelled Aerial Wire, 7/22, stranded, 100 ft. Terminals, War Office type, with nuts, per doz., Is. 6d. Aluminium Pulleys, ex-Government, each... Leading-.in Cable, heavily rubber-covered wire, per yard

Coils with Tappings, Loose Couplers, etc. wound to-order. Cardboard Cylinders, Enamel, Silk and Cotton-covered Wires

WATERLOO ELECTRIC CO., Electrical and Wireles. 129, WATERLOO ROAD (/ minute Waterloo Station)

Phone : HOP 5649. PRICE LISTS FREE.

JANUARY 20, 1923

rMITCHELFONES^ ■

Are not a spasmodic production to meet a sudden demand, but haye-been on the „ market for over three months, and during this period 27,000 have been distributed to the trade, and consequently we have " not been able to offer them direct to the

retail buyer. '

1,000 per week are now available, and we announce

DELIVERY FROM STOCK ' r

You post your order, or call at our premises and get them at once. Think b what this means to you—you, perhaps, who have been waiting and are still waiting. h

Standard resistance 4,000 ohms, double headgear with couble headstraps, comfortable, highly efficient, ^ and ioolproof

25/- per pair.

Special Terms to Traders and deliveries that will surprise you. B

MITCHELLS Electrical & Wireless Ltd., „ Postal Address: McDermott Road, Peckham, S.E.IS, Retail Address: 188, Rye Lane, Peckham, S,E,15« ^

I 'Phones: New Cross 1540/1541. |

GREAT BRITAIN'S GREATEST WIRELESS STORE

Headphones

HAMMOND and KING, Wireless Specialists, 51, BERWICK STREET, W.l.

Aerials Erected, Apparatus Manufactured and Installed. A Crystal Set for 15/- KING'S FOR VALUE A Crystal set for 15/- SETS OP PARTS : ' " BrunetJ" telephones 4,000 ohms with cords, £1 Is., post Is.; 12 x 4 Inductance 24 E S.W.G 3b., post Is.; 9 x 3.i inductance 24 E.S.W.G., 2s. 6d., post Is.; Mahogany Polished grooved ends per pair, large, Is. 8d., post 6d. ; Ditto, .small, IS. Gdg, post 6d. , Mahogany Polished Base, .arge, 2s. 9d., post 6d. ; Ditto, small, 28. 6d., post 6d. ; Slides rod drilled with terminal fitted per pair, lOd., post 8d. ; Knob and Plunger, per pair. Is., post 3d.; Crystal detectors, upright type, 3s. 6d., post 6d. ; Blocking condensers, ebonite. 3x2, 2s., post 8d.; Filament resistances, vs. 4d , post 6d.; Condenser Boxes, polished mahogany, 4 x 4 x 3i. 2s. 6d., post 6d.; Aerial Wire 7/22 Base copper 100 It,, 2s. lOd., post 8d. ; 1 Valve panel detector, complete set of parts with box, 15s., post Is. 6d. ; 1 Amp. Unit with box, £1 10s., post la. 6d.

2

4,000 ohms total Resistance.

Double Headband. Guaranteed highly efficient. Complete with Cords. Ball and socket joints ; highly polished nickel cases ; best

Tungsten steel magnets.

Splendid Crystal

Detector

Mounted on Ebonite.

2 9

Beaver Complete

Crystal Sets No, 1 unassembled ... 15/- No. 2 unassembled ... 20/- No. 3 assembled, ready

for use ... 24/-

Intervalve Transformers Ratio 5 to 1. Excellent Value. 15/-

ALL GOODS SENT POST FREE

BEAVER ELECTRICAL SUPPLY CO.' 109,REGENT STREET,LONDON,W.l

Telephone : GERRARD 1900 Special Terms to Trade. All Cheques and Postal Orders to ho crossed London Joint City and Midland Bank.

^tnaUur

E CONOMIC LE CTRI

1/ -

1 t-»s

91* V CRYSTAL DETECTORS, 6/6

// ^=5 r Write >

To-tfay for 40- Page WIRELESS A-lst Post Free

L4tl.

I

A

HEAD RECEIVERS From 12/6

250 lllus- -»| ENCLOSED CRYSTAL DETECTOR, 12/6 trations.

INDUCTANCES 60/-

VALVE HOLDERS, 19 lit' Head Office 10, FiTZROY

SQUARE, LONDON, W.I. Showroomsj . I Telephone:

303, EUSTON ROAD, N.W.t. I MUSEUM 1055 Branch Showrooms &■ Works TWICKENHAM

JANUARY 20, J923

-H5

HERE'b REAL RADIO SEM1CE 55

Telephones, best French, adjustable earpieces, 4,000 ohms £1 Os. Qd. n ji 1, ,, ,, . 8,000 ohms ... £1 2s. 6d. „ genuine "Brunet " steel.Headbands, 4,000 ohms ... £1 2s. 6cl it single earpiece with" cords an.d handle-, 4,000 ohms its. OcT Crystal Detectors, mounted on Ebonite, ball socket joint ... 2s. 6d'

Hertzlte Crystals ... ... _ ... ... Is. 6d. and 2s. Od' Wound Inductance, 12 in. x;4 in. wound with 22 enamel wire ... 38. 6tr Brass Rod and Slider, complete "with pluflger"(13 in. rod) .. lod* Rheostat, remarkable value * ... ' " . ... ... 2s. 6d" Valve Holders, each Od. with screwed legs and nhts ... is. 3d* Batteries, 4—5 volts, suitable for H.T. ... ... per doz, 5s Od* Phosphor Bronze Aerial Wire, 1/18, 100 ft. coils ... ... 2a. Od- Insulators, Reel 2, Large Egg, 6d.Shell ... - ... 6d. and Sd* Enamelled Aerial Wirei 7/22, stranded, 100 ft. ... 4s. 6d- Terminals, .War Office .type, with'nuts, per'dbz., Is. 6d. Telephone, 2s. Od. Aluminium Pulleys, ex-Government, each.,. ... -... Is. Od, Leading.in Gable, heavily rubber-covered wire, per yard „. 6d]

Coifs with Tappings, Loose Couplers, etc. wound to-order, Cardboard Cylinders, Enamel, Silk and Cotton-covered Wires WATEKLOO : ELECTRIC CO Electrical and Wireless 129, WATERLOO ROAD (/ minute Waterloo Station)

Phon© s HOP 5649. PRICE LISTS FREE.

rMlTChELFONES^ o

Are not a spasmodic production to meet a sudden demand, but have-been on the „ market for over three months, and during this period 27,000 have been distributed to the trade, and consequently we have " not been able to offer them direct to the

retail buyer. "!

1,000 per tveek are now available, and we announce

DELIVERY FROM STOCK

You post your order, or call at our premises and get them at once. Think what this means to you—you, perhaps, who have been waiting and are still waiting.

Standard resistance 4,000 ohms, double headgear with double headstraps, comfortable, highly efficient, and foolproof

25/^ per pair.

Special Terms to Traders and deliveries that will surprise you. B

MITCHELLS Electrical & Wireless Ltd., m Postal Address: McDcrmott Road, Pcckham, S.E.IS, Retail Address: 188, Rye Lane, Peckham, S,E,15« ^

■ 'Ptionea! New Cross 1540/1541. |

V>-uREAT BRITAIN'S GREATEST WIRELESS STORE

-BEGINNER'S GUIDE TO WIRELESS Fsplains In plain, everyday language, everything beginners wlsn to know about "Wireless Telegraphy.-

HOW TO ERECT, CONNECT, AND MAKE all the apparatus required for reception of telephony or morse, and fuir instructions and diagrams lor making coils, tuners, and complete valve and crystal sets. 112 pages, price X/- post free. SAXON RADIO CO. South Shore, BLACKPOOL \ 82 page Catalogue of Wireless Apparatus, 2d. post free.

HAMMOND and KING, Wireless Specialists, SI, BERWICK STREET, W.l.

Aerials Erected, Apparatus Manufactured and Installed. A Crystal Set for 15/- KING'S FOR VALUE A Crystal set for 15/- . SETS OF PABTS: ■ 1

" Brunety' telephones 4,000 ohms with cords, £1 Is., post Is. ; 12 x 4 Inductance 24 E S.W.G Ss., post Is.; 9 x 3^ inductance 24 E.S.W.G., 2s. 6d., post Is.; Mahogany Polished grooved ends per pair, large, Is. 8d., post 6d.; Ditto, .small, Is. 6ds, post 6d., Mahogany Polished Base. Jarge, 2s. 9d.j post 6d. ; Ditto, small, 2s. 6d., post 6d.; Slides rod drilled with terminal fitted per pair, lOd., post 8d. ; Knob and Plunger, per pair. Is., post 3d.; Crystal detectors, upright type, 3s. 6d., post 6d. .' Blocking condensers, ebonite, 8x2, 2s., post 3d.; Filament resistances, »S. 4d , post 64 ; Condenser Boxes," polished mahogany, 4 x 4 x Sh 2s. 6d,, post 6d.; Aerial • ir,ey*® ?®:8e copper 100 ft,, 2s, lOd., post 8d.; I Valve panel detector, complete set of parts with box, 16s,, post IS!'6d: ;:-l Amp. Unit with-box, £1 10s., post Is. 6d.

Headphones

2

4,000 ohms total Resistance.

Double Headband. Guaranteed highly efficient. Complete with Cords. Ball and socket joints ; highly polished nickel cases ; best

Tungsten steel magnets.

Splendid Crystal

Detector

Mounted on Ebonite.

2/9

Beavei Complete

Crystal Sets No. 1 unassembled, ... 15/- No. 2 unassembled ... 20/- No, 3 assembled, ready

for use ...24/-

Ihtervalve Transformers Ratio 5-to I. Excellent Value. 15/-

ALU GOODS SENT POST FREE

BEAVER ELECTRICA/ SDPPLY C0.^ 109,REGENT STREET;LONDON,W. 1

Telephone i GERRARD 1900 *VWZ*riH Special Terms to Trade. All Cheques and Postal Orders to be crossed London Joint City and Midland Bank.

Page 3: Amateur Wireless Magazine, Weekly, Sat 20th January 1923...Amateur Wireless Magazine, Weekly, Sat 20th January 1923. DONT MISS FREE MAP WITH CALL SIGNS NEXT WEEK Vol. 11, No. 33 SATURDAY,No

l>

Vol. 11, No. 33

urtltS'

and Electrics

January 20, 1923

WHAT CAUSES FADING?

' pHE problem of fading is of great xn- * terest, and though no solution has as

yet been arrived at, some little progress has been made by recent investigations.

Tests Amateur tests carried out in a district

some 200 miles from the nearest bi'oadcast- ing station seem to make it clear that no blame for the trouble can be laid at the door of the transmitting stations, and the theox'ies involving that link in the chain of broadcasting communication must therefore be ruled out. This leaves the two alternatives—the receiving apparatus and the. medium through which the waves travel in their passage from the transmit- ting aerials.

The tests were made within a radius of four miles, and it was found that, while none of the experimenters reported pei'fect reception of the whole programme, there was no similarity in the experiences re- garding fading. An item would be heard excellently at one point, and serious fading trouble would be met with at another point in respect of the samp item, while a few minutes later the position would be quite reversed. On one or two occasions the

fading occurred synchronously at all the stations.

Two of the stations where the tests were made were, however, only a few hundred yards from each other, yet there was a considerable difference in the reports by the operators. While apparently absolv- ing the transmitter,, the tests cannot be said to have helped much in pointing the way to a solution.

Theories In some quarters it has been argued that

the phenomena is due to the blocking of the grid condenser, caused by the use of grid leaks of insufficient value, the idea being that an overcharge, such as atmo- spherics, paralyses the valve for the time being, and the leak can only work away to gradually relieve it. A variable condenser and leak has been tried, also shorting of the grid condenser when fading takes place, and potentiometer control of the leak, but these expedients have not been found to improve matters.

Adherents to the belief that the atmo- spheric conditions are to blame are numerous, and one of the most popular- suppositions is "that clouds of moisture

passing backwards and forwards over a district may take away part of the energy of the transmitting station. It is only right to point out, however, that in aeroplanes wireless reception from the ground has been much better when the aeroplane was above the clouds than when below them. In addition, during the amateur tests men- tioned above a white mist lay on the ground at some of the receiving stations, while at the others- the conditions were clear. The results did not bear out that the mist had any effect.

Are Our Neighbours to Blame? A rather interesting speculation is that

fading is due to the behaviour of near-by receiving stations—those who offend in the matter of oscillations. If such a station at a very short distance be oscillating, it is' conceivable that its wave will come in practically as strong as the carrier wave of the broadcasting station. Before long a' point is bound to be reached xvhen these two waves will neutralise each other, so far as listeners-in on the particular sets which are receiving both are concerned >! that neutralising would cause fading—a{t any rate, that is the theory. G. A. F.

m

CONVERTED APPARATUS

'"PHESE self-contained sets are ex-Govcrnment instru^

ments modified so. as to be suit- able for broadcast reception. That on the left was originally a B Mark II detector-amplifier, but the wavelength range is now from 300 to 1,000 metres. A variable condenser is provided for fine tuning, and duolateral coils can be plugged in.

The other photograph shows what was formerly a C.W, Mark 111 transmitting set which is now a two-valve receiving set. The coils remain exactly as before. A variable conden- ser has been added, so that the range of wavelength is from 300 to 1,500 metres. A vario- meter is embodied to render very close tuning possible.

The instruments are retailed by Leslie MacMichael, Ltd., and were exhibited at the "Model Engineer" Exhibition.

ilit Wiiffiiil

Radio Mac II Converted Set. C.W. Mark 111 Set afte»* Conversion. 5

is

Vol. 11, No. 33

wririTi^ \i\y

and EWtr«^

January 20> 1923

WHAT CAUSE FADING?

' JTHE problem of fading is of great in- * tcrest, and though no solution has as

yet been arrived at, some little progress has been made by recent investigations. Tests

Amateur tests carried out in a district some 200 miles from the nearest broadcast- ing station seem to make it clear that no blame for the trouble can be laid'at the door of the transmitting stations, and the theories involving that link in the chain of broadcasting communication must therefore be ruled out. This leaves the two alternatives—the receiving apparatus and the medium through which the waves travel in their passage from the transmit- ting aerials.

The tests were made Within a radius of four miles, and it was found that, while none of the experimenters reported perfect reception of the whole programme, there was no similarity in the experiences re- garding fading. An item would be heard excellently at one point, and serious fading trouble would be met with at another point in respect , of the samp item, while a few minutes later the position would be quite reversed. -On one or two occasions the

fading occurred synchronously at all the stations.

■ Two of the stations where the,tests were made were, however, only a few hundred yards from each other, yet there was a considerable difference in the reports by the operators. While apparently absolv- ing the transmitter^ the tests cannot be said to have helped much in pointing the way to a solution. '

Theories In some quarters it has been argued that

the phenomena is due to the blocking of the- grid condenser, caused by the use of grid leaks of insufficient value, the idea being that an overcharge, such as atmo- spherics, paralyses the valve for the time being, and the leak can only work away to gradually relieve it. A variable condenser and leak has been tried, also shorting of the grid condenser when fading takes place, and potentiometer control of the leak, but these expedients have not been found to improve matters.

Adherents to the belief that the atmo- spheric conditions are to blame are numerous, and one of the most popular- suppositions is ".that clouds of moisture

passing backwards and forwards over a district may take away part of the energy of the transmitting station. It is only right to point out, however, that in aeroplanes wireless reception from the ground has been much better when the aeroplane was above the clouds' than when below them. In addition, during the amateur tests men- tioned above a white mist lay - on the ground at some-of the receiving stations,

. while at the others, the conditions were clear. The results did not bear out that the mist had any effect.

Are Our Neighbours to Blame ? A rather interesting speculation, is that

fading is due to the behaviour of near-by receiving stations—those who offend in the matter of oscillations. If such a station at a very short distance be oscillating, it .is' conceivable that its wave will come in practically as strong as the carrier wave of the broadcasting station. Before long a' point is bound to be reached when these two waves will neutralise each other, so far as listeners-in'on the particular sets which are receiving both are concerned>! that neutralising would cause fading—aft any rate, that is the theory. G. A. F.

1

CONVERTED APPARATUS

THESE self-contained sets f are ex-Government instru^

mentSi modified so as to be suit' able for broadcast reception. That on the left was originally a B Mark II defector'amplifier, but the wavelength range is now from 300 to 1,000 metres. A variable condenser is provided for fine tuning, and duolateral coils can be plugged in.

The other photograph shows what was formerly a C.W. Mark HI transmitting set which is now a twowalve receiving set. The coils remain exactly as before. A variable conden'

■ s.er has been added, so that, the range of wavelength is from 300 to 1^500 metres. A variO' meter is embodied to render Very close tuning possible.

The instruments are retailed by Leslie MacMichael, Ltd., and were exhibited at the " Model Engineer " Exhibition.

r

Radio Mac II Gonyerted Set, C.W. Mark III Set after Conversion.

Page 4: Amateur Wireless Magazine, Weekly, Sat 20th January 1923...Amateur Wireless Magazine, Weekly, Sat 20th January 1923. DONT MISS FREE MAP WITH CALL SIGNS NEXT WEEK Vol. 11, No. 33 SATURDAY,No

^matcur

ft .

52 JANUARY 20 1923

s i 1 ft ft

More About

Vario-couplers

Types Uses Construction

ft-. , ft ft ?1 Fig. 1.—UrdF.arv Type of Yario-coupler. S i ' i QdPtjPtja^ijjPiSidr'iJPdPLlPdPiJPclPdPi^ijrijrdP^clPitpcQ]

IN this article it is intended to deal only with those arrangements which have a

secondary or reaction coil rotating inside the primary coil.

The most usual type is where the axis on which the coil turns passes through the centre of the windings (Fig. i). It is necessary with this arrangement to leave a space between the turns for the spindle to pass through, which means a loss of efficiency since the continuity of the coil is broken. This can be overcome by adopt- ing the following method of pivoting the inner coil. The axis is fixed to opposite points on opposite circumferences on the smaller coil, and rotates in bearings at similar points on the larger coil. (This will be" clearly understood from the illus- tration, Fig. 2.)

It is obvious that the continuity of the winding is unaffected since the axis does not pass through the turns on either coil. Further, the control knob has to be turned through half a revolution (180 deg.) to change the coupling from maximum to minimum—from tight to loose. This 2 tq. i ratio is" especially valuable when the degree of coupling has to be very exactly defined, as is the case with the reception of telephony. Suitable sizes for the coils (for short wave work) are :

Outer or primary coil, 3^ in. outside diameter by 2^3 in. long.

Inner or secondary coil, 2^ in. outside diameter by 2 in. long. ' These sizes give a maximum degree of coupling which is not too tight to cause self oscillation, an important considera- tion where broadcast reception is con- cerned. The illustration, Fig. 2, shows a convenient way of mounting these coils with a switch for varying the primary in- ductance on top of the containing cabinet.

If the coils are to be used as an aerial tuning inductance and closed circuit in- ductance, the "ball " type of inner coil is more suitable for two reasons. Firstly, the degree of. coupling can be made much greater than with other arrangements, a desirable feature since there are no ill effects arising from tight coupling in this

case. Also the shape of the rotating part inside the A.T.I, is such that the capacity effect it has on the outer coil is constant. Hence a variation in coupling does not affect the tuning of the aerial circuit.

This type of former can be readily turned out of any hard wood and mounted on two short spindles or one continuous spindle (Fig. 3).

It is not advisable to use the spindle as the connections for the coil, for however

T\

Fig. 3,—Ball-type Rotor (Constant Capacity).

|P=|

:t=g

Fig. 2.—Fine-coupling Device.

carefully the rubbing contacts are made noises are produced on turning the con- trol knobs.

Since the coil need only rotate through 90 deg., connections can be established by flexible wires (covered) soldered to the ends of the winding.

It is advisable to note that the wind-

ing must be put on in two parts and joined at the centre, as it is only possible to wind "up the hill." The winding should be started at each end and continued up- wards (inwards), and the two ends then soldered together and tucked inside.

H. R.

Dielectric Constant of Mica IN an article in the "Physical Review,"

J. R. Weeks, Jnr. states that for samples of mica, without visible air films, the die- lectric constant ranged from 6.4 to 9.3. For sheets having air films the values were from 2.9 to 5,6. Sheets split from the sample which had given the value 2.9 were measured and the results varied from 6.6 to 8.4. Similar experiments confirm the belief that the low results are to be attri- buted to the presence of air. This pro- bably explains the reason for the wide divergence between values of the dielectric constant of mica given in handbooks.

A Loud-speaker for Eight Shillings

\ A /HY do loud-speakers cost so much ? * " I have just constructed an instru-

ment, for the modest sum of eight shil- lings, which gives results quite equal to those obtained from factory-built loud- speakers costing three or four pounds. The basis of the apparatus is an ex-army loud-speaker which was purchased from an advertiser in Amateur WIRELESS for the sum of seven shillings and sixpence.' This is an ear-piece with extra large diaphragm, and came, I fancy, from a trench-set. It is of 200 ohms resistance. The horn, pur- chased at a second-hand store for three- pence, Is an ordinary tulip-shape alu- minium horn from an old phonograph.

The fixing of the horn to the ear-piece presented some difficulties. It is essential that there should be an air-tight connec- tion, because the action of a loud-speaker depends on setting in motion the column of air between the diaphragm and that

portion of the horn where it begins to widen out. After several trials—soldering of two aluminium surfaces being thought out of the question—a piece of rubber tube of sufficient size was slipped over the end of the horn and then rubber and horn and ear-piece were tightly bound together with bare copper wire. The result is not beauti- ful to look at, but it answers. With three stages of note magnification Paris time signals can be heard all over the house, and London, Paris, Birmingham and Man- chester broadcasting really do "flood the room with music." There is very little distortion, which is probably due to the good design of the horn. Of course there must always be some distortion in a loud- speaker, apart altogether from that due to the note-magnifiers, because as the sound- waves broaden out in the horn they them- selves are distorted. This is reduced by good design. Ernest Langmead.

^matcur ^/ircleS^ 52 JANUARY 20 1923

s i-

i -s

Fig. 1.—Ordii.ary Type of Vario-coupler.

!N this article it ,is intended to deal only with those arrangements which have a

secondary or. reaction coil rotating ingide the primary coil.

The most usual type is where the axis on which the coil turns passes through the centre of the windings (Fig. 1). If is necessary with this arrangement to leave a space between the turns for the spindle to pass through, which means' a loss of efficiency since the continuity of the coil is broken. This can be overcome by adopt- ing the following method of pivoting the inner coil., The axis is fixed to opposite points on opposite circumferences on the smaller coil, and rotates in bearings at similar points on the larger coil. '(This wiU be clearly understood from the illus- tration, Fig. 2.).

It is obvious that the continuity of the winding is unaffected since the axis does not pass through the turns on either coil. Further, the control knob has to be turned through half a revolution (180 deg.) to change the coupling from maximum to minimum—from tight to loose. This 2 to. 1 ratio is'especially valuable when the degree of coupling has to be very exactly defined, as is the case with the reception of telephony. Suitable sizes for the coils (for short wave work) are;

Outer or primary coil, 3)^ in. outside diameter by 2^ in. long.

Inner or secondary coil, 2)4 in. outside diameter by 2 in. long. ' These sizes give a maximum degree of coupling which is not too tight to cause self oscillation, an important considera- tion where broadcast reception is con- cerned. The illustration, Fig. 2, shows a convenient way of mounting these coils with a switch for varying the primary in- ductance on top of the containing cabinet.

If the coils are to be used as an aerial tuning inductance and closed circuit in- ductance, the "ball " type of inner coil is more suitable for two reasons. Firstly, the degree of. coupling can be made much greater than with- other arrangements, a desirable feature since there are no ill effects arising from tight coupling in this

More About

Varkvcouplers

Types Uses Construction

case. Also the shape of the rotating part inside the A.T.I, is such that the- capacity effect it has on the outer coil is constant. Hence a variation in coupling does not affect the tuning of the aerial circuit.

This type of former can be readily turned out of any hard wood and mounted on two short spindles or one continuous spindle (Fig. 3).

It is not advisable to use the spindle as the connections for the coil, for however

T\

37 Fig. 3.—Ball-type Rotor

(Constant Capacity).

Fig. 2.—Fine-coupling Device.

carefully the rubbing contacts are made noises are produced on turning the con- trol knobs.

Since the coil need only rotate through 90 deg., connections can be established by flexible wires (covered) soldered to the ends of the winding.

It is advisable to note that the wind-

ing must be put on in two parts and joined at the centre, as it is only possible to wind "up the hill." The winding should be started at each end and continued up- wards (inwards), and the two ends then soldered together and tucked inside.

H. R.

Dielectric Constant of Mica IN an article in the "Physical Review,"

J. R. Weeks, Jnr. states that for samples of mica, without visible air films, the die- lectric constant ranged from 6.4 to 9.3. For sheets having air films the values were from 2.9 to 5.6. Sheets split from the sample which had given the value 2.9 were measured and the results valued from 6.6 to 8.4. Similar experiments confirm the belief that the low results are to be.attri- buted to the presence of air. This pro- bably explains the" reason for the wide divergence between values of the dielectric constant of mica given in handbooks.

A Loud-speaker for Eight Shillings

WHY do loud-speakers cost so much ? I have just constructed an instru-

ment, for the modest sum of eight shil- lings, which gives results quite equal to those obtained from factory-built loud- speakers costing three or four pounds.

-The basis of the apparatus is an ex-army loud-speaker which was purchased from an advertiser in Amateur Wireless for the sum of seven shillings and sixpence.' This is an ear-piece with extra large diaphragm, and came, I fancy,- from a trench-set. It is of 200 ohms resistance. The horn, pur- chased at a second-hand store for three- pence, is an ordinary tulip-shape alu- minium horn from an old phonograph.

The" fixing of the horn to the.ear-piece presented some difficulties. It is essential that there should be an air-tight connec- tion,: because the action of a loud-speaker depends on setting in motion the column of air between the'diaphragm and that

portion of the horn where it begins to widen out. After several trials—soldering of two aluminium surfaces being thought out of the question—a piece of rubber tube of sufficient size was slipped over the end of the horn and then rubber and horn and ear-piece were tightly bound together with bare copper wire. The result is not beauti- ful to look at, but it answers. With three stages of note magnification Paris time signals can be heard all over the house, and London, Paris, Birmingham and Man- chester broadcasting really do "flood the room with music." There is very little distortion, which is probably due to the good design of the horn. Of course there must always be some distortion in a loud- speaker, apart altogether from that due to the note-magnifiers, because as the sound- waves broaden out in the horn they them- selves are distorted. This is reduced by good design. ERNEST LANGMEAD.

Page 5: Amateur Wireless Magazine, Weekly, Sat 20th January 1923...Amateur Wireless Magazine, Weekly, Sat 20th January 1923. DONT MISS FREE MAP WITH CALL SIGNS NEXT WEEK Vol. 11, No. 33 SATURDAY,No

MNUARY 20, 1923 53 ^tnoieur ^fireles^

Repairing a Low-frequency

T ransf ormer

I I OW many amateurs have thrown away ^ * low-frequency transformers as use- less after they have given out!

One day whilst working on three valves, one H.F. and one L.F., I was interrupted by a scratching noise which rapidly grew in volume, succeeded by a loud final click and—silence. In fact, my L.F- transformer had ceased to function. At first I had visions of another going on a new transformer, but I thought that I would have a look inside first just to see what could be done. First- I connected the secondary of the transformer in series with a 1.5 volt battery and a pair of phones. A click was heard in the phones and another upon disconnecting, so, I thought,

the secondary is O.K. I repeated the test with the primary, but no loud click. Sub- sequently I found that the primary wind- ings had gone where the wire was started next to the iron core. As the wire is finer than hair I did not see how I could find the break, so with a small penknife I scraped away a little insulation from the visible portion of the wire nearest to the core, and with resin-cored solder soldered a length of fine copper wire on. I then tested with the phones and battery once more, using the new piece of wire as one terminal and the outside lead of the primary as the other. A welcome click was heard, which proved that I had estab- lished connection again, despite the fact

I

t. 1 :

li svi

1

m r

li, w.

Low-frequency Transformer. (Igranic Electric Co., Ltd.).

that there were probably several dozen turns lying idle. The next thing to see was—would it work. I connected up as usual and switched on. In came the sig- nals with a roar and rattle. A, G. W.

IN the last article Da mention was made H

of the rate at which ^ electrical vibrations U are set up in a trans- S mitting aerial. This ® is commonly referred to as the "fre- quency" of the vi- brations, or of the wave which they pro- duce. This wave travels through space at the same velocity as light. There is, in fact, a great deal in common between wireless waves and light waves, although you can "see" one and not the other. One thing, for instance, which they have in common is their speed. They both travel at the enormous speed of about 186,000 miles per second ! Moreover, that speed does not vary for different kinds of light waves (giving rise to the sensation of "red" or "blue" or "green," for instance), or for different kinds of wireless waves—"long" or "short" waves as they are called.

"Vibrating " the Aerial Now it is not a very difficult thing to

imagine this wave motion being set up in the space surrounding a transmitting aerial. We know what a wave on the sea looks like : a series of hills and hollows, ups and downs, and we can depict a wire- less wave similarly. If you make a point on a sheet of paper with a pencil, and then from it draw a "waggly" line across the page, you may make these represent the transmitting aerial and the wireless wave set up by it when it is vibrated elec- trically. Now the hills or crests of this wavy line must be a certain distance apart, and this distance is usually called the wave-length. It may be defined as the distance between any two successive crests.

If the aerial is vibrated very quickly the successive crests of the resulting wave

Notes for the Novice.

Some Simple Definitions

111

S i

will be very close together—that is, the wavelength will be small. If the aerial is vibrated more slowly the crests will follow each other at longer intervals— that is, the wavelength will be longer. In other words, the greater the frequency the smaller the wave-length. This can be demonstrated quite easily. Assume that the wavy line runs from the pencil point to the edge of the paper and that there are 1,000 wave crests in this distance. If, now, you superpose on this another wavy line having only 500 crests extending over the same distance, it will be obvious that ■the distance between the latter crests must be twice the distance between the former. That is, when you halve the frequency you double the wavelength. Similarly, if you double the frequency you halve the wavelength, and so on.

Wavelength and Frequency Suppose you want to set up a wireless

wave having a wave-length of one mile. Well, since the wave, whatever its length, will travel at a speed of 186,000 miles per second, it follows that you will have to vibrate your aerial at a rate of t86,ooo times per second in order to do so. Or, again, if you want to transmit on a wave of half a mile length you will have to vibrate your aerial at twice the former rate, that is, at 372,000 times per second. This can be expressed as a general law by

186,000 saying that frequency = wave.len.gth;

In working this as a formula, of course, the wavelength must be expressed in miles. In practice, however, it is more customary to calcu- late wavelengths in metres or feet.

It is also customary in practice to speak of "oscillations" instead of "vibrations." Instead of saying that you "vibrate" the aerial at a certain "rate," the phraseology of wireless ordains that you should say that you "oscillate " it at a certain "frequency."

Maintaining Oscillations When you vibrate, or oscillate, an

ordinary violin string you must take care that it doesn't come into contact with any- thing. If you touch it with a stick, or a book, or your finger, it will cease to oscillate. You must protect or shield it from anything which would tend to pre- vent it from oscillating. The same is true with respect to an aerial in which you want to maintain oscillations; it must be shielded from anything which might pre- vent it from oscillating also. This is usually referred to as "insulating" the aerial. "Old Hand."

Whilst listening-in to an American broadcasting station, Mr. J. E. Samuel, of Aberystwyth, distinctly heard the clapping of hands of people in the room when an orchestral item was encored.

The directing of aircraft by ordinary wireless means is said to be giving better results than the system of transmitting signals from a cable laid along the line of route.

JANUARY 20. 1923 ^mokut* ^/ircleS5

Repairing a Low-frequency

Transformer

I I OW many amateurs have thrown away * ' low-frequency transformers as use- less after they have given out!

. One day whilst working on three valves, one H.F. and one L.F., I was interrupted by a scratching noise which rapidly grew in volume, succeeded by a loud final click and—silence. In fact, my L.F- transformer had ceased to function. At first I had visions of another £i going on a new transformer, but I ■ thought that I would have a look inside first just to see what could be done. First" I connected the secondary of the transformer in series with a 1.5 volt battery and a pair of phones. A click was heard in the phones and another .upon disconnecting, so, I thought,

the secondary is O.K. I repeated the test with the primary, but no loud click. Sub- sequently I found that the primary wind- ings had gone where the wire was started next to_ the iron core. As the wire is finer than hair I did not see how I could find the break, so with a small penknife I scraped away a little insulation from the visible portion of the wire nearest to the core, and with resin-cored solder soldered a length of fine copper wire on. I then tested \vith the phones and battery once more, using the new .piece of wire as one terminal and the outside lead of the primary as the other. A welcome click was heard, which proved- that I had estab- lished connection again, despite the fact

mm I

.

Msa! If c

Low-frequency Transformer. (Jgranic Electric Co., Lid.).

that there were probably several dozen turns lying idle. The next thing to see was—would it work. I connected up as usual and switched on. In came the sig- nals with a roar and rattle. A. G. W.

IN tjie last ■ article mention was made

of the rate at which electrical vibrations are set up in a trans- mitting aerial. This is commonly referred to as the "fre- —

quency" of the vi- brations, or of the wave which they pro- duce. This Wave travels through space at the same velocity as light. There is, in fact, a great deal in common between wireless waves and light waves, although you can "see" one and not the other. One thing, for instance, which they have in common is their speed. They both travel at the enormous speed ..of about 186,000 miles per second! Moreover, that speed does not vary for different kinds of light waves (giving rise to the sensation of "red" or "blue" or "green," for instance), or for different kinds of wireless waves—"long" or "short" waves as they are called.

"Vibrating " the Aerial Now it is not a very difficult thing to

imagine this wave motion being set up in the space surrounding a transmitting aerial. We, know what a wave on the sea looks like : a series of hills and hollows, ups and downs, and we can depict a wire- less wave similarly. If you make a point on a sheet of paper with a pencil, and then from it draw a "waggly" line across the page, ■ you may make these represent the transmitting aerial and the wireless wave set up by it when it is' vibrated elec- trically. Now the hills or ctests of this wavy • line must be a -certain distance apart, and this distance is usually called the wave-length. It may be defined as the distance between any two successive crests.

If the aerial is vibrated very quickly the successive crests of the resulting wave

Notes for the Novice.—Ill

Some Simple Definitions

will be very close together—that is, the wavelength will be small. If the aerial is vibrated more slowly the crests will follow each other at longer intervals— that is, the wavelength will be longer. In other words, the greater the frequency the smaller the wave-length. This can be demonstrated quite easily. Assume that the wavy line runs from the pencil point to the edge of the paper and that there are 1,000 wave crests in this distance. If, now, you superpose on this another wavy line having only 500 crests extending over the same distance, it will be obvious that the distance betwe"en tfie latter crests must be twice the distance between the former. That is, when you halve the frequency you double tjie wavelength. Similarly, if you double the frequency you halve the wavelength, and so- on.

Wavelength and Frequency Suppose you want to set up a wireless

wave having a wave-length of one mile. Well, since the wave, whatever its length, will travel at a speed of 185,000 miles per second, it follows that you will have to vibrate your aerial at a rate of 1.86,000 ■times per second in order to do so. Or, again, if you want tq -transmit on a wave of half a mile length you will have to vibrate your aerial at twice the former rate, that is, at, 372,000 times per second. This can be expressed as a general law by

186,000 saying that frequency = wave.length;

In working this as a S formula, of course, ^ the wavelength must g bq expressed in i miles. In practice, @ however, it is more Jg] customary to calcu-

late wavelengths in metres or feet.

It is also customary in practice to speak of "oscillations" instead of "vibrations." Instead of saying that you "vibrate" the aerial at a certain "rate," the phraseology' of wireless ordains that you should say that you "oscillate " it at a certain "frequency."

Maintaining Oscillations When you vibrate, or oscillate, an

ordinary violin string you must take care that it doesn't come into 'contact with any- thing. If you touch it with a stick, or a book, or your finger, it will cease to oscillate. You must protect or shield it from .anything which would tend to pre- vent it from oscillating. The same is true with respect to an aerial in which you want to maintain oscillations; it must be shielded from anything which might pre- vent it from oscillating also. This is usually referred to as "insulating" the aerial. "Old Hand."

Whilst listening-in to an American broadcasting station, Mr. J. E. Samuel, of Aberystwyth, distinctly heard the clapping of hands of people in the room when an orchestral item was encored.

The directing of aircraft by ordinary wireless means is( said to be giving better results than the system of transmitting signals from a cable laid along the line of route.

Page 6: Amateur Wireless Magazine, Weekly, Sat 20th January 1923...Amateur Wireless Magazine, Weekly, Sat 20th January 1923. DONT MISS FREE MAP WITH CALL SIGNS NEXT WEEK Vol. 11, No. 33 SATURDAY,No

^mateur ^fireks5 54 JANUARY 20, 1923

0 V

High-frequency Amplifiers - a a

a Transformer'coupled :; ' Resistance'coupled :: Reactance'capacity Coupled a a ■ a n®®®®®®®®®®®®®®®®®®®®!®®®®®®®®®®®®®®®®®®®®®®®®®®®®®®®®®®®®®®®®®®®®®®®! i

THE object of using a high-frequency amplifier in a receiver is usually to

increase the range and not the signal strength, although it does do the latter to some extent. Very weak signals may not have enough energy to make a rectifier

fix into valve holders so that they may be changed easily and quickly when listening-in.

Owing to the number of transformers required for receiving on all wavelengths this type is expensive to buy and trouble-

'-0 Fig. 1—

Connection ^ Diagram of LT

Transformer Coupling.

HI HT

T# TT

Fig. 2.—'Con- nection Diagram

of Resistance Coupling. L-j-

Fig. 3.—Con- nection Diagram R of Reactance-

capacity Coupling. LT

function, and so they are not heard at all. If by means of a high-frequency amplifier these signals are magnified before reach- ing the rectifier, then they* will have enough energy to make themselves audible.

Types There are three types of high-frequency

amplifiers in common use: (i) trans- former-coupled, (2) . resistance-coupled, and (3) reactance-capacity-coujaled. They all magnify signals before they are recti- fied, and it will therefore be understood that the magnification takes place at the frequency which corresponds to their wavelength. This is why they are some- times called " radio-frequency ampli- fiers," to distinguish them from ampli- fiers of rectified signals called " audio frequency amplifiers" or "note magni- fiers."

Transformer Coupling In the first type the magnified radio-

frequency impulses are conveyed to the next valve, which may be another high- frequency valve or a rectifier, by means of a transformer. This is connected up in the same way as a low-frequency trans- former and is shown in Fig. 1. These high-frequency transformers have no iron core.

As the frequencies of incoming signals vary so greatly over even a small band of wavelengths, one transformer will only be suitable for receiving signals be- tween certain limits of wave-length. It is therefore necessary to have a set of transformers, each wound with different amounts of wire, for receiving over a large range. They are usually made to

some to make. When properly designed, however, they give very good results. If wound with resistance 'wire the' trans- formers cover a slightly larger band of wavelengths, and signal strength is nearly as good. Some experimenters _say that these transformers do not " transform " at all, but have an entirely different action.

Resistance Coupling The second type makes use'of a resist-

ance in the anode circuit, as shown in Fig. 2. This resistance should be as large as possible for the H.T. voltage and is usually about 50,000 ohms. The con- denser may be of about .0002 mfd. capa- city and R2-about 2 megohms. This type is not quite as effifcient 'as the transformer- coupled type, and is of no use on wave- lengths below about 1,000 metres.

Reactance-capacity Coupling The reactance-capacity type is the most

effic'ient and the most popular with ex- perimenters. The connections are shown in Fig. 3. The inductance L is tuned to the exact wave-length of the incoming signals. The grid coupling condenser may be .0002 mfd. and R about 2 megohms. The advantage of this type is that a reactance from the rectifier may be coupled to the inductance L to produce beats for C.W. reception, without radia- tion.

The principle upon which it works is as follows : Although any inductance has some resistance, when tuned to a certain wavelength it has an infinitely high re- sistance to currents at that frequency, and in the case of an amplifier all the ampli- fied impulses pass to the grid-coupling condenser and do not leak away through

the anode circuit. In the resistance- coupled type these currents do leak away a little, and if the resistance is raised there is not sufficient voltage on the anode for the valve to function properly. The inductance, however, has a fairly small direct-current resistance.

Oscillation All types of high-frequency amplifiers

are liable to self-oscillation and howling, due to an excessive negative charge on the grid or grids. This can,be overcome by connecting all the grids in parallel and taking a lead to a potentiometer, so .that they may all be given a small posi- tive charge if necessary. The potentio- meter is placed across the accumulator. The inductance for a reactance-capacity type amplifier may be a basket-type coil, with a tuning condenser of not more than .0003 mfd. capacity. As with the trans- former type, different coils will be needed for different wavelengths, but they are easier and cheaper to make than trans- formers. RADION.

® \/\/\y\/\y\/v\/\/\/\/®

Variable Grid-leak

I FIE accompanying sketch shows an * idea for a variable grid leak which

works very well. As will be seen, it con- sists merely of a circular base -which may be ebonite or fibre, on which is'mounted a switch arm that is connected to one of the

© ©

Variable Grid-leak

terminals c. The leak D is an indian inl line and contact is made to it by the con- tact studs e which are screwed down tight. The farther round the switch arm i: placed the longer leak is placed in circuit. The first contact stud, of course, is con- nected to the other terminal. H. R.

Ask " Amateur Wireless " to send you a list of practical books. Sent gratis and post free.

• nvntexxt 54 JANUARY 20, 1923

■1 ; "r , : ■■ . ' ■:: : ; ^ • •• • • %

High-frequency Amplifiers

Transformer-coupled :: ' Resistance-coupled Reactance-capacity Coupled

I "HE object of using a high-frequency fix into valve hojders so that they may ' amplifier in a receiver is usually to he changed easily arid quickly when

increase the range and not the signal listening-in. strength, although it does do the .latter to Owing , to the number, of transformers some extent. Very weak signals may not required for receiving on all wavelengths have enough energy to make a rectifier this type is' expensive to buy and t'rouble-

HT NT

Fi,;. l._ Connection Diagram of LT

Transformer Coupling.

Fig; 2.—Con- nection Diagram

of Resistance Coupling. (_j

HT

tF

Fig. 3.—Con- nection Diagram R of Reactance-

capacity Coupling. LT

function, and so they are not heard at all. If by means of a high-frequency amplifier these signals are magnified before reach- ing the rectifier, then they will have enough energy to make themselves audible.

Types There are three types of high-frequency

amplifiers in common use : (i) trans- former-coupled, (2) , resistance-coupled,, and (3) reactance-capacity-coupled. They all magnify signals before they are recti- fied, and it will therefore be understood that the magnification takes place at the frequency which corresponds to their wavelength. This is why they are some- times called " radio-frequency ampli- fiers," to" distinguish them- from ampli- fiers of rectified signals called "audio frequency amplifiers" or "note inagni- ficrs."

Transformer Coupling In. the first type the magnified radio-

frequency impulses are conveyed to the next valve, which may be another high- frequency • valve or a rectifier, by means of a transformer. This is -connected up in the same way as a low-frequency trans- former and is shown in Fig. 1. These high-frequency transformers have no iron core.

■ As the frequencies of incoming signals vary so greatly over even a small band of wavelengths, one transformer will only be suitable for receiving signals be- tween certain "limits of wave-length. It is therefore necessary to have a set of transformers, each wound with different amounts of wire, for receiving over a large range. They are usually made to

some to make." When pioperl-y designed, however, they give very -good regults. If wound with resistance" "wire the* trans- formers cover a slightly larger band of wavelengths, and signal strength is nearly as good. jSome experimenters say that these transformers do" not transform " at S j • 4 > -r- ■ .st -■ ."> r- all, but have an entirely different action.

Resistance Coupling The second type makes tfse'of a resist-

ance in the anode circuit, as 'shown in Fig. 2. This resistance should be as large as possible for the' H.T. voltage and is usually about 5o;oo0 ohms. The con- denser may be oh about .0002 mfd. capa- city and R2-about 2 megohms. This type is not quite as efficient'as the transformer- coupled type, and "is of no use on wave- lengths below about 1,000 metres.

Reactance-capacity Coupling The reactance-capacity type is the most'

efficient and the most popular with ex, perimenters. The connections are shown in Fig. 3. The inductance E is tuned to- the exact wave-length of the incoming signals. , The grid coupling condenser may be .0002 mfd. and R -about 2 megohms. The advantage of this type is that a reactance from' the Tectifier may be coupled to the inductance "L to produce beats for C.W. reception, without radia- tion.

The principle upon which it works is as follows: Although any inductance has some resistance, when tuned to a certain wavelength it has an infinitely high re- •sistance to currents' at that frequency, and in the case of an amplifier all the ampli- fied impulses pass to the grid-coupling condenser and do not leak' away" through'

the anode circuit. In the resistance- coupled type these currents do leak away a little, and if the resistance is rajsed there is not sufficient voltage on the anode for the valve to function properly. The inductance, however, has a fairly small direct-current resistance.

Oscillation All types of high-frequency amplifiers

are liable to self-oscillation and howling, due to an excessive negative charge on the grid or grids. This can,he overcome by connecting all the grids in parallel and taking a lead to a potentiometer, so .that they may all be given a small posi- tive charge if necessary. The potentio- meter is placed across the accumulator. The inductance for a reactance-capacity type amplifier may be a basket-type coil, with a tuning condenser of not more than .0003 mfd. capacity. As with the trans- former type, different coils will be needed for different wavelengths, but they art easier and cheaper to make than trans- formers. Radion.

Variable Grid-leak

I HE accompanying sketch shows an * idea for a variable -grid leak which

works very well. As will be seen, it con- sists merely of a circular base -which may be ebonite or fibre, on which is mounted a switch arm fha't is connected to'-one of the

0 0

Variable Grid-leak

terminals C. Tile leak D is ari.indian inl line and contact is made to it by the con- tact studs E which are screwed down tight. The farther round the switch arm i< placed the longer leak is placed in circuit. The first contact stud, of course, is con- nected to the other terminal. H. R.

Ash " Amateur Wireless " to send you a list of practical books. Sent gratis and post free.

/

Page 7: Amateur Wireless Magazine, Weekly, Sat 20th January 1923...Amateur Wireless Magazine, Weekly, Sat 20th January 1923. DONT MISS FREE MAP WITH CALL SIGNS NEXT WEEK Vol. 11, No. 33 SATURDAY,No

JANUARY 20, 1923 55 ^mottur ^irelasj

It Speaks for itself

and in no uncertain voice

THE WORLD'S STANDARD LOUD SPEAKER

aMPUON

WIRELESS LOUD

SOUNDING RECEIVERS

are supplied in a series of

Ten Models

Suitable for every service:

The Home,

Laboratory

and the

Concert Hall

At Prices

ranging from

£2 :10 : 0

to

£15 :15 : 0

"MUSIC MASTER" HORN Type AR 13. 120 ohms £6:0:0 Type AR 15. 2.000 ohms ... £6:2:6

DAILY DEMONSTRATIONS

at the GRAHAM

SHOWROOMS The ALGRAPHONE

SALON 25-26, Savile Row, Regent Street, W.l 'Phone: Regent 1075

" Graham " Wireless Pro- ductions include "High Efficiency" Telephone Headsets of improved design and construction. The " Graham" is the best Head Gear money

can buy.

Full particulars Jor warded upon request. Ask for Folder A, W.

Patentees and Manufacturers :

ALFRED GRAHAM

AND COMPANY

St. Andrew's Works, Crofton Park LONDON 'Phone: Sydenham 952.

S.E.4 'Grams : Xavalhada, Brock, London

SCOTLAND ; Mr. F. M. Milligan, 25, Renfrew Street, GLASGOW.

IRELAND ; Mr. Alex. R. Munday, 41, Chichester St., BELFAST.

JANUARY 20, 1923 55 ^makur ^ireLes^

It Speaks for Itself ,y

and in no uncertain voice

THE WORLD'S STANDARD LOUD SPEAKER

WIRELESS LOUD

SOUNDING RECEIVERS

are supplied in a series, of

Ten Models

Suitable for every service:

The dome,

Laboratory

and the

Concert Hall

At Prices

ranging from

£2 :10 : 0 to

£15 :15 : 0

DAILY DEMONSTRATIONS

at the GRAHAM

SHOWROOMS The ALGRAPHONE

SALON 25-26, Savile Row, Regent Street, W.l 'PhoneJ Regent 1075

'•music IV1 ASTER" HORN Type AR 13. 120 ohms £6 : O : 0 Type AR 15, 2,000 ohms ... £6:2:6

" Graham " Wireless Pro- ductions include " High Efficiency" Telephone Headsets of improved design and construction. The " Graham" is the best Head Gear money

can buy. Full particulars Jor warded upon request* Ask for Folder A. JV.

Patentees and Manufacturers :

ALFRED U RAH AM

ANil COMPANY

St. Andrew's Works, Crofton Park LONDON 'Phone: Sydenham 952.

S.E.4 'Grams : Xavalhada, Brock, Londoa

, SCOTLAND: Mr. F. M. Milligan, 25, Renfrew Street, GLASGOW.

IRELAND ; Mr. Alex. R. Munday, 41, Chichester St., BELFAST,

Page 8: Amateur Wireless Magazine, Weekly, Sat 20th January 1923...Amateur Wireless Magazine, Weekly, Sat 20th January 1923. DONT MISS FREE MAP WITH CALL SIGNS NEXT WEEK Vol. 11, No. 33 SATURDAY,No

^mattur ^ircles^ 56 JANUARY 20, 1023

r -HULLO

Do YOU ICx^ow Us? If not, why not ?

UJ

COMPLETE SETS of PARTS for

MAKING VARIABLE CONDENSERS

EVERYTHING READY to ASSEMBLE and

CONSISTS of the FOLLOWING:

Accurate Aluminium" Fixed and Moving Vanes, Large and Small Spacer Washers, Centre Square Spindle (Screwed Ends, 2 B.A.), 3 Side Rods, 13 Nuts and 13 Brass Washers (2 B.A.), Pointer-scale 0-180, Terminals 3 bushes, Spring Coil Washers, Best Quality Knob with 2 B.A. Nut in Centre.

ALL HIGHEST QUALITY GOODS

REVISED PRICES, WITHOUT EBONITE Approximate Capacity

in Microfarads .0015

.OOl

.00O7S

.OOOS

.0003

.0002

.OOOl

Vernier

No. of Plates 85

57

43

29

19

13

7

3

Price 9/-

6/6

5/6

4/6

3/-

2/3

2/-

1/9

DRILLED EBONITE ENDS 1 /- pair Postage and Packing: 1 set, 1 /-; 2 sets, 1/5; 3 sets, 116

If more than 3 sets kindly include ample for packing and carriage, as the value given does not permit of my paying same.

No Connection With Any Other Advertiser

HeadphoneS

Genuine

"BRUNET" (FRENCH)

A Simply Splendid Phone for Radio

DOUBLE RECEIVERS Complete with Cords

25/- pair Post Free

SEE YOU GET THE GOODS!

/ Sell these on MERIT and RECOMMENDATION

BRITISH PHONES

4,000 ohms. Approved P.M.G. Stamped B.B.C.

21/- 22/6 25/-1

(Double) Post I/-

BRITISH PHONES (Single) 4,000 ohms

Approved P.M.G. Stamped B.B.C, Complete with Cord and Handle

12/6

ASSEMBLED CONDENSERS (Circular Discs.) Complete Sets. .OOl - - - 12/6 .0005 - - 8/6 .

Post and Packing, 1/3 Set

IL

| RIGHT OPPOSITE |

| D A L Y'S J | GALLERY DOOR |

M. RAYMOND

27, LISLE STREET, W.C.2

IBU

'Phone :

0G3C

GERRARD 4637

jyililllllllllllllllllllllllllillilllllllllllll^ = To avoid mistakes, EE = this address is close EE = to Charing X Road EE EE a n d Leicester = |E Square Tube = illlllllHIIINIilllllllllllJIIIHIIHIllllnil

DB0 DEDQ 300 30E 00

^tnaltur ^lreLes_5 56 JANUARY 20, mi

!□!

r L

Do YOU Kutow Us? I'" <»ot, wh> not ?

COMPLETE SETS of PARTS for

MAKING VARIABLE CONDENSERS

EVERYTHING READY to ASSEMBLE and

CONSISTS of the FOLLOWING:

Accurate Aluminium" Fixed and Moving Vanes, Large and Small Spacer Washers, Centre Square Spindle (Screwed Ends, 2 B.A.), 3 Side Rods, 13 Nuts and 13 Brass Washers (2 B.A.), Pointer-scale 0-180, Terminals 3 bushes, Spring Coil Washers, Best Quality Knob with 2 B.A. Nut in Centre.

ALL HIGHEST QUALITY GOODS

REVISED PRICES, WITHOUT EBONITE Approximate Capacity

in Microfarads .0015

.OOl

.00O7S

.0005

.0003

.0002

.OOOl

Vernier

No, of Plates 85

S7

43

29

"" 19

13

7

3

Price 9/-

6/6

S/6

4/6

31-

2/3

21-

1/9

DRILLED EBONITE ENDS 1 /- pair Postage and Packing: 1 set, l[-j 2 sets, 113; 3 sets, 116

!f more than 3 sets kindly include ample for packing and carriage, as the value. ■ given does not permit of my paying same.

No Connection With Any Other Advertiser

66 Genuine

BRUNET" (FRENCH)

A Simply Splendid Phone for Radio

DOUBLE RECEIVERS Complete with Cords

25/- pair FW Free

SEE YOU GET THE GOODS!

I Sell these on MERIT and RECOMMENDATION

BRITISH PHONES 4,000 ohms. Approved P.M.G.

Stamped B.B.C.

21/- 22/6 2r;- (Double) Post I/-''

r

BRITISH PHONES (Single) 4,000 ohms

Approved P.M.G. Stamped B.B.C. Complete with Cord and Handle

12/6

ASSEMBLED CONDENSERS .(Circular Discs.) Complete Sets.

.OOl - - - 12/6

.COOS - - 8/6 • Post and Packing, 1/3 Set

IL

| RIGHT OPPOSITE |

iDALYSj | GALLERY DOOR | iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiint

IHC

M. RAY M OW •

27, LISLE STREET, W.C.2

'Phone ;

UBU 0EIE

GERRARD 4637

nnp

piiiiiiiiiiiiiiiiiiiiiiiiiHiiiiiiiiiiiiiniK . To avoid mistakes, =

= this addresf is close S = to Charing X Road = Sand Leicester= S S q u a r e .TubeS niiiiiiiiiiiiiiiiiiiiiiiiiiiijiniiiiiiiiiiiini

DEE DtXi

Page 9: Amateur Wireless Magazine, Weekly, Sat 20th January 1923...Amateur Wireless Magazine, Weekly, Sat 20th January 1923. DONT MISS FREE MAP WITH CALL SIGNS NEXT WEEK Vol. 11, No. 33 SATURDAY,No

JANUARY 20, 1923 57 ^rrvatiar ^/ireles^

EVERYBODY

E=10l=

nl

We do not offer you " something for nothing," nor is this advertisement a catchpenny one. Goods supplied are value for money, both as to quality and price. We leave our customers to be the best judges. 'Naff said!

IMPORTANT NOTICE. Owing to the enormous demand for goods, and the difficulty in obtaining sufficient supplies at the

moment for postal supplies, I ask your kind indulgence re same.

ALL ORDERS DESPATCHED AT THE EARLIEST POSSIBLE DATE. All Articles Sent on Approval. No Catalogues Issued.

ALL FOLLOWING GOODS POST FREE AT THE SPECIAL POST PRICES ATTACHED Aerial Wire. Genuine 7/22 bare copper stranded. 100 ft. hanks,

daily market prices (postal supplies uncertain at present). Switches. Not common rubbish on fibre, but a real good article,

brass on ebonite. S.P.S.T., 1/6 (by post, 2/=); S.P.D.T., 2/= (by post, 2/6); D.P.S.T., 2/6 (by post, 3/=); D.P.D.T., 3/= (by post, 3/6).

Filament Resistances. I have 3 type's, all highest quality. For 1 valve, 2/6 (by post, 3/3); for 2 valves, 3/= (by post, 3/6) ; and for 3 valves, 3/6.

Insulators^ green or white, egg type, 2d, each (not sent by post). Lead in Tubes. Ebonite, with brass ends. Best quality. 6 in.,

1/=; 9 in., 1/2; 12 in., 1/4 (not sent by post). Crystal Detectors on Ebonite. Well made, two designs. 2/6 (by

post, 3/3) and 3/3 (by post, 3/9). And they are worth it! Crystal Detector. Dust proof, glass covered, horizontal type. Very

handsome design ; our own pattern. 4/6 (by post, 5/3). Detector for Two Crystals. Horizontal type, thoroughly well made.

(Some people ask 19/6 for the same design !) I am sure you will be satisfied to pay 4/= (by post, 4/9).

Grid Leak and Condenser, .0003. ^Absolutely perfect in design and qualitv. It is not cheap, but does the work. Price 3/9 (by post, 4/3). '

Our 5-pIece Terminals beat the world. Id. each (no post orders at present).

Terminals, with hole for telephone leads. Beautifully finished, com- plete with hut/and washer. 2d. each (not less than 1 doz. sent by post, price 2/6).

Ebonite Valve Holders, with 8 nuts. 1st quality, 1/3 (by post, 1/8); 2nd quality, 1/1 (by post, 1/5).

W.O. Terminals. Highly finished and polished, suit highest class • set. With nut and washer. 2d. each (not less than 1 doz. sent

by post, price 2/6). Terminals. Extra good quality, small size, 4 B.A., W.O. pattern.

8 for 1/= (by post, 1/4). Terminals. 4 B.A. Small, round pattern, pretty design, with nut

and washer. 8 for 1/= (by post, 1/4). Very Large Terminals. Superb quality. 2 B.A. Complete with 2

nuts and 2 washers. 2 for 8d. (by post, 1/=). I can supply you with Terminals, various designs, all really

good and cheap. No rubbish supplied. Intervalve Transformers, low frequency, 5-1. On approval. 14/= (by

post, 15/=). Ebonite Dials. 0-180. Bored in centre. I/= each (by post, 1/6). Knobs. Bushed 2 B.A., specially good quality, 4Kd. each (by post,

7d.). Switch Arms. 3 designs. All complete with laminated arm, bushes,

nuts, washers, etc. Prices, l!-- (by post, 1/6),1/6 (by post, 2/=), 2/= (by post, 2/6).

Fixed Condensers. First-class value, .0003, .0005, .001, .002, .003. Scientifically constructed. 1/3 each (by post, 1/6); also .004, 1/6 (by post, 1/9). These arc with terminal's on ebonite.

Slider Knobs and Plunger. 4d. (by post, 7d.). Slider, knob and plunger, with 13 in. brass rod. The lot, 7d. No post orders accepted.

Oojah Basket Coils, 7 in set, 5/= (postal supplies uncertain at present). H.T.. Batteries. 30 volt, 6/= (by post, 7/6). H.T. Batteries. 60 volt, 12/= (by post, 13/6).

XJKTSOX-ICITEIID H, S. PETTITT,

37, Robertson Road, BRIGHTON. 10/1/23. " Received Condenser .parts to-day, and they surpass all my expectations."

SAMUEL LOWE, 22, Noble Terrace, GATESHEAD-ON-TYNE. 30/12/22.

"The Condensers received by me were first class and people would not believe me when I told them the price."

R. H. FEUSTER-RUSSELL, 21, Hadlow Road, TONBRIDGE, Kent. 11/1/23.

". . . . I consider them the most remarkable Con- denser value on the market."

To CALLERS: We Sell All Component Parts CHEAP! BRASS RODS, NUTS, WASHERS, SCREWS, VALVE SOCKETS, VALVE PINS, STOP PINS, LARGE SPACERS, SMALL

SPACERS, BUSHES, etc., AT WHOLESALE PRICES. ANY QUANTITY SUPPLIED.

It is impossible to advertise everything, but you can rest assured that you cannot get quality or prices obtainable here, at any other establishment

| RIGHT OPPOSITE |

IdalvsI

I GALLERY DOOR | iiiiiiiiiiiiiiiiiiiiiiiiiimiiiiiiitiiiiiiiii

DO DEE

M. RAYMOND

27, LISLE STREET, W.C.2 |

'Phone: GERRARD 4637

30O 3SC DEO DEO

EE To avoid mistakes, = = this address is close EE = to Charing X Road EE EE a n d Leicester EE = Square Tube = FlIilHIIIIIlllllililllllillllliilllllllilllilli

DEE " I ?ir=£j DEI

JANUARY 20, 1923

\=1B\

We do not offer you "something for nothing," nor is this advertisement a -atchpenny one. Goods supplied are value for money, both as to quality and price. We leave bur customers to be the best judges. 'Naff said!

IMPOFT-VNT NOTICE. Owing to the enormous demand for goods, and the difficulty in obtaining sufficient supplies at the

moment for postal supplies, I ash your kind indulgence re same.

ALL ORDERS DESPATCHED AT THE EARLIEST POSSIBLE DATE. A.II Articles Sent on Approval. No Catalogues Issued.

ALL FOLLOWING GOODS POST FREE AT THE SPECIAL POST PRICES ATTACHED Aerial Wire. Genuine 7/22 bare copper stranded. 100 ft. hanks,

daily market prices (postal supplies uncertain at present). Switches, Not common rubbish on fibre, but a real good article, . brass on ebonite. S.P.S.T., 1/6 (by post, 2/=); S.P.D.T., 2/=

(by post, 2/6); D.P.S.T., 2/6 (by post, 3/=); D.P.D.X, 3/- (by post, 3/6).

Filament Resistances. I have 3 type's, all highest quality. For 1 valve, 2/6 (by post, 3/3); for 2 valves, 3/= (by post; 3/6); and for 3 valves, 3/6.

insulators, green or white, egg type, 2d, each (not sent by post). Leadyin Tubes. Ebonite, with brass ends. Best quality. 6 in.,

1/=; 9 in'., 1/2; 13'in.,-1/4 (not sent by post). Crystal Detectors on Ebonite. Well made, two designs. 2/6 (by

post, 3/3) and 3/3 (by post, 3/9). And they are worth it I Crystal Detector. Dust proof, glass covered, horizontal type. Very

handsome, design ; our own pattern. 4/6 (by post, 5/3), Detector for Two Crystals. Horizontal type, thoroughly well made.

(Some . people ask 19/6 for the same design!) I am sure you will be satisfied to pay 4/= (by post, 4/9).

Grid Leak and Condenser, .0003. Absolutely perfect in design and quailtvl It is not cheap, but does the work. Price 3/9 (by post, 4/3); ' . .

Our 5-piece Terminals beat the world. Id, each (no-post orders at present). ... • *

Terminals, with hole for telephone leads.' Beautifully'finished, com- plete with hiit.-ancr-washerrf 2d. each (not less than x doz. sent by post, price 2/6).

Ebonite Valve Holders, with 8 nuts, 1st quality, 1/3 (by post, 1/8); 2nd quality, 1/1 (by post, 1/5).

W.O. Terminals. Highly finished and polished, suit highest class • set. With nut,ancl washer, 2d, each (not less than 1 doz. sent

by post, price 2/6).. Terminals. Extra good quality, small size, 4 B.A., W.O. pattern.

8 for 1/= (by post, 1/4). Terminals. 4 B.A. Small, round pattern, pretty design, with nut

and washer. 8 for !/=> (by post, 1/4). Very Large Terminals. Supex-b quality. 2 B.A. Complete with 2

nuts and 2 washers. 2 for 8d. (by post, I/=). A can .supply you with Terminals, various designs, all really

good and cheap. No rmxbisli sujbpUed. Intervalve Transformers, low frequency, 5-1. On approval. 14/= (by

post, 15/=). Ebonite Dials. 0-180. Bored In centre. 1/= each (by post, 1/6). Knobs. Bushed 2 B.A., specially "good quality, 4V2d. each '(by post,

7d.). " Switch Arms. . 3 designs. All complete with laminated arm, bushes,

nuts, washers; etc. Prices, l/» (by post, 1/6), 1/6 (by post, 2/=), 2/= (by post, 2/6).

Fixed Condensers. First-class value, .0003, .0005, .001, .002, .003. Scientifically constructed, 1/3 each (by post, 1/6); also .004,' 1/6 (by post, 1/9). These are with terminals on ebonite.

Slider Knobs and Plunger. 4d. (by post, 7d.). Slider, knob and plunger, with- 13 in, brass rod. The lot, 7d, No post orders accepted.

Oojah Basket Coils, 7 in set, 5/= (postal supplies uncertain at present). H.Tc Batteries, 30 volt, 6/= (by post, 7/6). H.T. Batteries, 60 volt, 12/= (by post, 13/6).

XJ2WS03L.X03:TES3 h. s. PETTITT,

37, Robertson Road, -BRIGHTON. 10/1/23. " Received Condenser parts to-day, and they surpass

all my expectations." ' " '

SAMUEL LOWE, 22, Noble Terrace, GATES HE AD-ON-TVNE. ^ 80/12/22.

"The Condensers received by me were first class and people would not believe me when I told them the price."

R. H. FEUSTER-RUSSELL, 21, Hadlow Road,

TONBRIDGE, Kent, 11/1/23. ,c. . . . I consider them' the most remarkable Con- denser value on the market."

To CALLERS: We Sell All Component Parts CHEAP! BRASS RODS, NUTS, WASHERS, SCREWS, VALVE SOCKETS, VALVE PINS, STOP PINS, LARGE SPACERS, SMALL

SPACERS, BUSHES, etc., AT WHOLESALE "PRICES. ANY QUANTITY SUPPLIED.

It is impossible to advertise everything, but you can rest assured that you cannot get quality or prices obtainable here, at any other establishment

HiiiiiiiiiiiiiiiiiHiiiiiiiiiiiiiiiiiniiiiiiniH = | RIGHT OPPOSITE |

IdalvsI

I GALLERY DOOR | iiiiiiiiiimiiiiiimiiiiiiiiiiiiiiimiiiiii

so DSO

M. RAYMOND

27, MSLE STREET, W C.2 |

'Phone; GERRARD 4637

oso DE :

= To avoid mistakes, = = this address is close = =- to Charing X Road = E=and Leicester — == Square Tube = ililHllllilllllliliillHIIHIiHililillllflllM

OEIO ^ J nr=J mi

Page 10: Amateur Wireless Magazine, Weekly, Sat 20th January 1923...Amateur Wireless Magazine, Weekly, Sat 20th January 1923. DONT MISS FREE MAP WITH CALL SIGNS NEXT WEEK Vol. 11, No. 33 SATURDAY,No

^nuxteuf ^irelesj JANUARY 20t 1923

(57

v <v V -9- S>. s

!»5Ul

m

\ W.

f

so be sure

you dont miss N91

f JOW can I charge my Accumulator at home ? Instead of buying Coils, can I wind my own ? How can I receive louder speech

and music ?

The answer to these and scores of many other similar questions will be found in No. 1 of the new monthly " Modern Wireless." If you don't need the information at the moment, you are quite likely to want it later—therefore, if you are wise, you will keep every number handy for ready reference.

But be sure that you start with No. 1, so that your files will be complete.

Every month "Modern Wireless" will consist of over 100 pages (in No. 1 there are 112 pp.) of informative and dependable articles from the pens of the best known Radio engineers and experimenters. If you wish to keep abreast of the wonderful developments that are daily taking place—you must take care not to miss a single issue.

Owing to the huge demand, there was some little delay in getting No. 1 out to time.

MODERN WIRELESS

Edited by JOHN SCOTT-TAGGART, F.Inst.P,, assisted by E. REDPATH and PAUL D. TYERS, and published on the I5th of every month. Sold by all Booksellers and Newsagents and published by

SRartui fress-IM Publishers of authoritative wireless literature DEVEREUX COURT. STRAND. W.C.2.

10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42.

Contents of No. 1 1 Northolt." ' Receiving Radio Signals from Electric Lighting

Wires." 'The Transmission of Wireless Waves." ' A 4,000-mile Receiver." I A Two Valve Broadcast Receiver." • valve Receivers Employing Crystal Detectors." ' An Experimental Station at Gerrards Cross." II Dual Amplification." ' A Simple Winder for Wave-wound Coils." ' The Dynatron." ' Charging Accumulators at Home." 'The Sine Wave." ' A Great New Wireless Invention." ' A Conducting Cement." ' The Sinking of the ss. ' Hammonia.e" ' A Simple Wireless Telephone Transmittef•.,,•. 'The Outlines of Wireless." ' Double Reaction—A New Development." ' An Amateur Wireless Society and How to

Conduct It." ' Directional Wireless." ' How to Make a Simple Broadcast Receiver

Using a Crystal Detector." ' Digest of Current Radio Literature." 'The World's Land Stations: Their Calls and Wave-lengths." ' Choosing a Broadcast Receiver." ' Wireless Operators and Their Careers." ' 2 XB." ' Recent Additions to Our List of Expenmemal

Call-Signs." 1 Map of European Wireless Stations." ' The Construction of a Valve Panel." ' How to Make a Note-amplifying Panel." ' A Vernier Condenser and Its Construction," 1 A Home-made Telephone Transformer." ' Methods of Fixing Windings and Inductances." 1 a Simply-made Grid-leak." ' Times of Regular Transmissions." ' Greenwich Time by Wireless." ' How I Heard the American Concert."? ' Patents of the Month." ' Experimental Licences." " Book Reviews." ' With the Manufacturers." • a Page for the Absolute Beginner."

MONTHLY

MARSHA IJT- Ali.

^thoteur tyircUs3 5S JANUARY ?0 '923

(S7

f v \\ «- S-

5^

HUMl

\

f

so be s^re

you don't miss N91

TJOW can I charge my Accumulator at home ? Instead of buying Coils, can I wind my own? How can I receive louder speech

and music ?

The answer to these and scores of many other similar questions will be found in No. 1 of the new monthly "Modern Wireless." If you don't need the information at the moment, you are quite likely to want it later—therefore, if you are wise, you will keep every number handy for ready reference.

But be sure that you start with No. 1, so that your files will be complete, '

Every month " Modern Wireless" will consist of over 100 pages (in No. 1 there are 112 pp.) of informative and dependable articles from the pens of the best known Radio engineers and experimenters. If you wish to keep abreast of the wonderful developments that are daily taking place—you must take care not to miss a single issue.

Owing to the huge dem d. there was some little delay in" getting No. 1 out to time.

MODERN WIRELESS

Edited by JOHN SCOTT-TAGGART, F.Inst.P., assisted by E. REDPATH and PAUL D. TYERS, and published on the I5th of every month. Sold by v

all Booksellers and Newsagents and published by

Slcitlto f rcas.ICtd "UBUSHERS OP AUTHORITATIVE WIRELESS LITERATURE DEVEREUX COURT. STRAND.^/.C.2.

Contents of No. 1 \

10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. .

4 Northoit." ' Receiving Radio Signais from Electric Lighting

Wires." 'The Transmission of Wireless Waves." ' A 4,000-mile Receiver." • A Two Valve Broadcast Receiver." 4 Valve Receivers Employing Crystal Detectors." 4 An Experimental Station at Gerrards Cross." " Dual Amplification." ' A Simple Winder for Wave-wound Coils." ' The Dynatron." 4 Charging Accumulators at Hotne." 'The Sine Wave." ' A Great New Wireless Invention." ' a Conducting Cement." 'The Sinking of the ss. 4 Hammonia.E" 'A Simple Wireless Telephone Transmitter/! 'The Outlines* of Wireless." ' Double Reaction—A New Development." ' An Amateur Wireless Society and How to

Conduct It." 1 Directional ,Wirele5S." 4 How to Make a Simple Broadcast Receiver Using a Crystal Detector." 4 Digest of Current Radio Literature."

'The World's Land Stations: Their Calls and Wave-lengths." ' Choosing a Broadcast Receiver." 4 Wireless Operators and Their Careers." ' 2 XB." t- ^ « Recent Additions to Our List of Expenmemal

Call-Signs." ' Map of European Wireless Stations." 'The Construction of a Valve Panel." 1 How to Make a Note-amplifying Panel." 4 A Vernier Condenser and Its Construction." « a Home-made Telephone Transformer." 4 Methods of Fixing Windings and Inductances." ' A Simply-made Grid-leak." 'Times of Regular Transmissions." 4 Greenwich Time by Wireless." ' How I Heard the American Concert/! i' Patents of the Month." 4 Experimental Licences." " Book Reviews." 4 With the Manufacturers." . ^ page for the Absolute Beginner."

MONTHLY

MARSHA L-I- A I*

Page 11: Amateur Wireless Magazine, Weekly, Sat 20th January 1923...Amateur Wireless Magazine, Weekly, Sat 20th January 1923. DONT MISS FREE MAP WITH CALL SIGNS NEXT WEEK Vol. 11, No. 33 SATURDAY,No

JANUARY 20. 1923 •^/i«les5

Broadcast Opera

Amateur Telephony

Short Waves

Reports con- tinue to come

in that telephonic transmissions from America are being picked up by amateurs in all parts of the

country. The most surprising point at first sight is that these messages had never been heard until about two months ago; then one observer who was working on short waves in the small hours was amazed at hearing items of a broad- cast programme from Newark, New Jer- sey. Almost at once other wireless men began to announce that they were able to hear Transatlantic transmissions, and now they are picked up quite regularly by dozens of people. The truth is that until the possibility of hearing Uncle Sam's wireless voice was known not one owner of a wireless set in a thousand ever thought of tuning in the short wavelength at 2 ak emma. There is a certain amount of commercial and shipping work on 300 metres, but otherwise there is nothing to hear. Then until last summer the number of valve receiving sets in use in this country was a very small one indeed. It grew rapidly as the summer waned, and with the departure of the hot weather, atmospherics, which are particularly bad in America, ceased their usual spoil-sport antics. Winter nights are especially favourable for wonderful results.

But there is another point which is most remarkable—the more aerials there are in use for reception the better is our chance of picking up faint and distant transmis- sions. Even when the set is so perfectly controlled that it causes interference with no one else it is radiating weak waves which exactly correspond to the oscilla- tions that it is receiving. Hence if two sets are working on the same wavelength within a fairly short radius their aerials will influence one another just as do the secondary and reaction coils of the set, each "boosting up" the signals received by the other. This "aerial reaction," as we may call it, may become one of the most important factors in wireless, for in the future stations may be designed to take full advantage of the interaction of twin or triple aerials.

Amateurs, though eclipsed to some ex- tent by the prevalence of broadcasting, are by no means so silent as some corre- spondents imagine. If you care to tune down to about 200 metres you will find

that all our old friends are still very much in evidence ;2jZ, 2LZ, 2OD and 2 O N, for instance, transmit on most evenings, and they are by no means the only ones.

It used to be thought that short waves travelled badly, but now that telephony has crossed the Herring Pond on a carrier- wave of 360 metres, we must revise our ideas a little. Most of the London amateurs are heard regularly in Paris on quite small receiving sets, and many of them are picked up in places as far afield as Berne, Nice and Cadiz. The lower wavelengths are coming into their own, and many en- thusiasts hold that the future of wireless lies largely with them.

jia sa M fx iW p? pr A correspondent asks whether by con-

necting a potentiometer directly across the accumulator he will not be practically "shorting" it. Many people seem to have a similar doubt, and certainly the little coil of wire does look as if it would give the L.T. battery a fairly free passage for its current. Ohm's Law shows that the current passed is equal to the voltage divided by the resistance. Hence if a 200-ohm potentiometer is shunted across a 6o-volt accumulator the current passing is only 6/20oth of an ampere, or 30 milli- amperes, which is so small that we need not worry about it. At the same time a switch should be provided to cut out the battery, otherwise much of its "juice" will eventually leak away.

^4 -54 -54 -54 pk dtr PK fy The President of the Sheffield Wireless

Association, one of the most go-ahead in, the. North, has been bringing home to the members the iniquity of condition No 2 of the broadcast licence. Admittedly the new P.M.G. takes a wide view and grants experimental licences to most of the serious applicants for them; still this does not alter the fact that a monopoly has been established, and monopolies are sel- dom satisfactory things except for those that own them. Mr. Lloyd, in his address, pointed out that when 1,000,000 wireless sets were in use the Broadcasting Com- pany would have a revenue of ^250,000 a year from licences alone, to say nothing of the royalties charged on complete sets and on parts. The whole position is un- satisfactory and calls for united and de- cided action on the part of wireless asso- ciations.

It is to be hoped that we shall see ere long the promised improvement in the quality of broadcast programmes. 2 L O's

Potentiometers and the L.T. Battery

Licence Clause No. 2 The Hello Girl

orchestra, now, we believe, a perma- nent feature, is most pleasant to listen to, but some of its items do not seem well suited for broadcasting purposes. An occasional lecture on wire- less subjects by an expert would be wel- comed by thousands of enthusiasts. The gramophone and the pianola should be barred out as wireless "turns."

^4 ^4 A4 ^4 pSr iw iw PX As I write it seems as if these pious

aspirations are likely to be fulfilled, for the loud-speaker in the next room is de- livering in the most delightful manner Mozart's "Magic Flute," transmitted direct from the Royal Opera House, Covent Gar- den. There was a slight delay in starting, then 2 L O announced "switching over to Covent Garden." Came a rather indistinct sound of the scraping of fiddles mingled with toots on the flute and with other more or less pleasant noises. It was the orchestra tuning up. (This, by the way, was the only part of grand opera that appealed to the late Shah of Persia.) A sudden silence, then an outburst of applause as the conductor took his place, and next moment the overture was in full swing. The effect of a salvo of hand-claps is most extraordinary if you are close to the instrument or have the phones on your head, sounding rather like strong atmo- spherics, but at a little distance you can almost imagine yourself in the theatre and you can hardly resist adding your own enthusiastic applause. The solos and the choruses are coming through to per- fection. There was a little fading at the very outset, but no such effect is now noticed. The signal strength is only a trifle less than that of 2 L O's own trans- missions, which, considering the size of the Covent Garden stage, is remarkable. The success of this experiment in broad- casting (and it is a very real success) marks the opening of an entirely new era in wireless. The B.B.C. has promised us future operatic programmes, and there is little doubt that in the future we shall be able to hear plays from the theatres, services from the great churches, and even speeches made in both Upper and Lower Houses of Parliament.

The telephone girl was listening-in for the first time. "Hello! Hello! Hello!" called the headphones. "Number en- gaged," she said automatically, then relapsed into blushing confusion.

Thermion. ■

JANUARY 20. 1923 59 ^Imotmr ^Uulesj

Broadcast Opera

Amateur Telephony

Short Waves

Reports con- tinue to come

in that telephonic transmissions, from America are being picked up by, amateurs in all parts of the

most surprising point that these messages

country." The at first sight is had never been heard until about two months ago; then one, observer who was working on short waves in the small hours was amazed at hearing items of a broad- cast programme from Newark, New Jer- sey. Almost at once other wireless men began to announce that they were able to hear Transatlantic transmissions, and now they are picked up quite regularly by dozens of people. The truth is that until the possibility of hearing Uncle Sam's wireless voice was known not one owner of a wireless set in a thousand ever thought of tuning in the short wavelength at 2 ak emma. There is a certain amount of commercial and shipping work on .300 metres, but otherwise there is nothing to hear. Then until last summer the number of valve receiving sets in use in this country was a very small one indeed. It grew rapidly as the summer waned, and with the departure of the hot weather, atmospherics, which are particularly bad in America, ceased their usual spoil-sport antics. Winter nights are especially favourable for wonderful results.

But there is another point which is most remarkable—the more aerials there are in

. use for reception the better is our chance of picking up faint and distant transmis- sions. Even when the set is so perfectly controlled that it causes interference with no one else it is radiating weak waves which exactly correspond to the oscilla- tions that it is receiving. Hence if two sets are working on the. same wavelength within a fairly short radius their aerials will influence one another just as do the secondary and reaction coils of the set, each "boosting up" the signals received by the other. This "aerial reaction," as we may call it, may become one of the most important factors in wireless, for in the future stations may be designed to take full advantage of the interaction of twin or triple aerials.

Amateurs, though eclipsed to some ex- tent by the prevalence of broadcasting, are by no means so silent as some corre- spondents imagine. If you care to tune down to about 200 metres you will find

that all our old friends are still very much in evidence jzJZ, 2LZ, 2OD and 2 O N, for instance, transmit on most evenings, and they are by no means the only ones.

It used to be thought that short waves travelled badly, bu,t now that telephony has crossed the Herring Pond on a carrier- wave of 360 metres, we must revise our ideas a little. Most of the London amateurs are heard regularly in Paris on quite small receiving sets, and many of them are picked up'in places as far afield as Berne, Nice and Cadiz. The lower wavelengths are coming into their own, and many en- thusiasts hold that the future of wireless lies largely with them.

<54 >SA A4. JW. w fir pif fS' A correspondent asks whether by con-

necting a potentiometer directly across" the accumulator he will not be practically "shorting" it. Many people seem to have' a similar doubt, and certainly the little coil of wire does look as if it would give the L.T. battery a fairly free passage for its current. Ohm's Law shows that the current passed is equal to the voltage divided by the resistance. Hence if a 200-ohm potentiometer is shunted across a 6o-volt accumulator the current passing is only 67200th of .an ampere, or 30 milli- amperes, which is so small that we need not worry about it. At the same time a switch should be provided to cut out the battery, otherwise much of its "juice" will eventually leak away.

fV f A fir <3S The President of the Sheffield Wireless

Association, one of the most go-ahead in, the North, has been bringing home to the members the iniquity of condition No 2 of the broadcast licence. Admittedly the new P.M.G. takes a wide view and grants experimental licences to most of the serious applicants for them; still this does not alter the fact that a monopoly has been established, and monopolies are sel- dom satisfactory things except for those, that own them. Mr. Lloyd, in his address, pointed out- that when 1,000,000 wireless sets were in use the Broadcasting Com- pany would have a revenue of ,£250,000 a year from licences alone, to say nothing of the royalties charged on complete sets and on parts. The whole position is un- satisfactory and calls for united, and de- cided action on the part of wireless asso- ciations.

It is to be hoped that we shall see ere long the promised improvement in the quality of broadcast programmes. 2 L O's

Potentiometers and the L.T. Battery

Licence Clause No. 2 The Hello Girl

orchestra, now, we believe, a perma- nent feature, is most pleasant to listen to, but some of its items do not seem well suited for broadcasting purposes. An occasional lecture on wire- less subjects by an expert would be wel- comed by thousands- of enthusiasts. The gramophone and the pianola should be barred out as wireless, " turns."

As I write it seems as if these pious aspirations are 'likely to be fulfilled, for the loud-speaker in the next room is de- livering in the most delightful manner Mozart's "Magic Flute," transmitted direct from the Royal Opera House, Covent Gar- den. There was a slight delay in starting, then 2 L O announced "switching over to Covent Garden." Came a rather indistinct sound of the 'scraping of fiddles mingled with toots on 'the flute and with other more of less pleasant noises. It was the orchestra tuning up. (This, by the way, was the only part of grand opera that appealed to the late Shah of Persia.) A sudden silence, then an outburst of applause as the conductor took his place, and next moment the overture was in full swing. The effect of a salvo of hand-claps is most extraordinary if you are close to the instrument or have the phones on your head, sounding rather like strong atmo- spherics, but at a little distance you can almost imagine yourself in the theatre and you can hardly resist adding your own enthusiastic applause. The solos and the choruses are coming through , to per- fection. There was a little fading at the very 'outset, but no such effect is now noticed. The signal strength is only a trifle less than that of 2 L O's own trans- missions, which, considering the size of the Covent Garden stage, is remarkable. The success of this experiment in broad- casting (and it is a very real success) marks the opening of an entirely new era in wireless. The B.E.C. has promised us future operatic programmes, and there is little doubt that in the, future we shall be able to hear plays from the theatres, services from the great churches, and even speeches made in both Upper and Lower Houses of Parliament.

The telephone girl was listening-in for the first time. "Hello ! Hello ! Hello ! " called the headphones. "Number en- gaged," she said automatically, then relapsed into blushing confusion.

Thermion. •

\

Page 12: Amateur Wireless Magazine, Weekly, Sat 20th January 1923...Amateur Wireless Magazine, Weekly, Sat 20th January 1923. DONT MISS FREE MAP WITH CALL SIGNS NEXT WEEK Vol. 11, No. 33 SATURDAY,No

^tnaieur 60

"a

i 6 1

Eb s a a i a

a

F iwn

3>-<J h T\

IMWWVWW

Hl-

HT \_0

Fig. 1.—Circuit Diagrai of Transmitter.

i ?] i i

• § a %

5L P is the amateur station owned by Mr. L. W. Pullman, and located in Golders

Green Road, London, N.W. Its trans- missions are well known to most wireless enthusiasts in the London area, and on this account alone the photographs on this page will be of considerable interest. Mr. Pullman's interest in wireless began twelve years ago, and during the ensuing time he has built and scrapped no less than nine sets, and yet with the present apparatus he makes. no claim to-special efficiency, so who knows but that this may follow the rest, though assuredly it will be followed by another.

1 ?l &

■ fi. Ml % ■

•ft- ft ft ft

•ft ft ft ft

Transmitter The present transmitter, which is to be

seen on the top of the receiving cabinet in the protographs, is a modified ex-army C.W. Mark III instrument. The tuning coil has been rewound with fifty turns of No. 18 wire tapped at the 3rd, 5th, pth, nth, 13th, 15th, 25111, 35th and 45th turns. The ball-reaction coil is wound with

: *

m

i mm. ■

"51 'mommm

mm

*<

General View of the 5 L P "Wireless Den.

5LP

An illustrated

an amateur-eqi

mitting and rec

—that of Mr. L

of Golders Gr

—N.V T

No. 28 wire and the variometer with No. 18. The circuit, which is shown by the diagram Fig. 1, is of the ordinary choke-control type. In the figure referred to A is a variometer and B the main aerial inductance. The tuned variometer is in- dicated at C and the reactance coil at D; E and F are choke coils. The microphone transformer is shown at H, and it will be observed that in connection with this is a change-over switch and also a plug to cut the latter out. The low- and high-tension batteries are indicated by LT and HT re- spectively. A feature of the choke is that the core is movable in order to make it possible to vary the effect produced. High-tension Generator

One of the most interesting points about the transmitter is the fact that the high- tension current is obtained from a hand- driven generator, made by Evershed and Vignoles-, which produces a current of 20 milliamps. at 1,000 volts with the greatest ease. The use of this instrument

obviates the trouble and expense of a motor-generator or rectifier, and Mr. Pull- man states that it gives excellent results. Change-over Switch

Another point of interest is the change- over switch, which will be observed on the

be seen on the le the experimental cu.it. The round the lightning arre Receiver

The receiver is ;

:

m

m 1

8S.S

Close-up Photograph of the Apparatus REFERENCES 4-

1 to 5.—Valves. 6.— H. F. transformer. 7.— Three - way switch. 8. —Filament resist- ance for H.F. valve. 9.—Grid leak change- over switch. 10.—Grid condenser. 11.—L.F. transformer tappings. 12.-—Filament resist- ance . for detector. 13. -— H.F. variable tuning- condenser.

5 Ift O 0

czz □ 19 on: a 20 0 0 0 0 21

14

i 1 o

i o 8

17 10 " 13

O G)

0e

m.

Fig. 2.—Key Diagram showing- Disposition of Receivi

right of the transmitter. The switch is arranged, lo change over aerial, earth, and low- and high-tension positive and nega- tive, so that when transmitting the receiver is dead. Pressure on .the white button, to

11. F., one detector The last three va.

-of switches, can Armstrong supei from which excel 1

^maKur tyircless 60

, S a.

a i 'S

i a- a

.fi- fe

■a ■fi' a-

a i 6

Ml

3>-«

Fig. 1,—Circuit Diagram of Transrqitter.

5L P is the amateur station owned by Mr. L. W. Pullman, and located in Golders

Green Road, London, N.W. Its trans- missions are well known tp most wireless enthusiasts in the London area, and on this account alone the photographs on this page will be of considerable interest. Mr.- Pullman's interest in wireless began twelve years ago, and during the ensuing time he has built and scrapped no less than nine sets, and yet with the present apparatus he makes, no claim to special efficiency, so who knows but that this may follow the rest, though assuredly it will be followed by another. Transmitter

The present transmitter, which is to be seen on the top of the receiving cabinet In the protographs, is' a modified ex-army" C.W. Mark III instrument. The tuning coil has been rewound with fifty turns of No. iB wire tapped at the '3'rd, 5th, pth, nth,' xjth,. 1.5th, 25th, 35th and 45th turns. The ball-reaction coil is wound with

:

I

m - . * ;

r -■ M

An illustrated

an amateur-eq

mitting and re<

—that of "Mr. L

oP Golders Gr

—N.\ w

No. 28 wire and the variometer with No. 18. The circuit, which is shown by the diagram Fig. 1, is of the ordinary choke-control .type. In the figure referred to A is a variometer and B the main aerial inductance. The tuned variometer is in- dicated at C and the reactance coil at D; K and K are choke coils. The microphone transformer is shown at II,, and it will be observed that in connection with this is a change-over switch and also a plug to cut the latter out. The low- and high-tension batteries are indicated by LT and HT re- spectively. A feature of the choke is that the core is movable in order to make it possible' to vary the effect produced. TIinh'tension Generator

One of the most interesting points aboui the transmitter is the fact that the high tension current is obtained from a hand- driven generator, made by Evershed and Vignoiesy which produces a Current' of 20 . milliamp-Sr at 1,000 volts with the greatest ease. The use of this instrument

obviates the trouble and expense of a motor-generator or rectifier, and Mr. Pull- man states that it gives excellent results. Change-over Switch

Another point of interest is the change- over switch, which will be observed on the

^be seen on the le t the experimental

cu.it. The round . the lightning arre Receiver

The receiver is ;

1

I 1

% P. ; jj sm

m m gmm M 1

1 1 Close-up Photograph of the Apparatus

REFERENCES 4- 1 to 5.—Valves. 6.— H.F. transformer. 7.—f . Three - way switch. 8.—Filament resist- ance. for H.F. valve, . 9, —Grid leak change- overswitch. io.-:Gri(i condenser. 11.—E.F. transformer tappings. • 12.—Filament resist- ance .for detector, 13. — H.F. variable tuning- condenser..

5 IS O 0 0 c^: 0 19 '20 0 ■» 0 0 21

a 15

6=r. Jo t o o .'X"' o Y ; b ie O 12 O s

10 13 0 ®

0e

m. 17

-vc Fig. 2,—Key Diagram showingvDIsposition of Receivi

right w-of . the - transmitter. The ■ switch is arranged. ±0 change-over aerial, earth, and low- 'and high-tension positive and nega- tive, so"" that when transmitting the receiver is dead. Pressure on,the white button, to

H.F., one detector The last three vai

;of switches, can Armstrong, supei from which excel 1 Igj General View of the 5 L P Wireless Den.

® ■ ...

Page 13: Amateur Wireless Magazine, Weekly, Sat 20th January 1923...Amateur Wireless Magazine, Weekly, Sat 20th January 1923. DONT MISS FREE MAP WITH CALL SIGNS NEXT WEEK Vol. 11, No. 33 SATURDAY,No

60 61

H 1

f

t!

ess Den.

5LP

An illustrated description of

an amateur-equipped trans-

mitting and receiving station

—that of Mr. L. W. Pullman,

of Golders Green, London,

T -N.W.

wire and the variometer with The circuit, which is shown by

tram Fig, i, is of the ordinary mtrol type. In the figure referred

variometer and B the main aerial ice. The tuned variometer is m- at C and the reactance coil at D; are choke coils. The microphone ner is shown at H, and it will be 1 that in connection with this is a iver switch and also a plug to cut r out. The low- and high-tension are indicated by L T and H T re-

ly. A feature of the choke is that is movable in order to make it

to vary the effect produced.

obviates the trouble and expense of a motor-generator or rectifier, and Mr. Pull- man states that it gives excellent results. Change-over Switch

Another point of interest is the change- over switch, which will be observed on the

be seen on the left of the switch, places the experimental artificial aerial in cir- cuit. The round box just above contains the lightning arrester Receiver

The receiver is a 5-valve set, having one

nsion Oenerator f the most interesting points about smitter is the fact that the high- current is obtained from a hand- generator, made by Evershed and S which produces a current of iamps. at 1,000 volts with the ease. The use of this instrument

wmm.

s ......

V

Mil m ' m

Close-up Photograph of the Apparatus REFERENCES

1 to 5.—Valves. 6.— H. F. transformer. 7. — Three - way switch. 8. —Filament resist- ance for H.F. valve. 9.—Grid leak change- over switch. 10.—Grid condenser. 11.—L.F. transformer tappings. 12,—Filament resist- ance . for detector. 13. — H.F. variable tuning condenser.

IT

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az: m

® ©

REFERENCES

Key Diagram showing-Disposition of Receiving Units.

right of the transmitter. The switch is arranged to change over aerial, earth, and low- and high-tension positive and nega- tive, so that when transmitting the receiver is dead. Pressure on the white button, to

H.F., one detector, and three L.F. valves.' The last three valves, by an arrangement

.-of switches, can be converted into the Armstrong super-regenerative receiver, from which excellent results are obtained.

£3

Receiving Valves From right to left on the panel

the H.F. valve with a H.F. varial transformer, and under this is th condenser. The next valve is the and above it and slightly to the double-pole switch is fitted which various values of grid-leaks to Below the detector valve there is variable condenser, and on the rij is a 5-way switch which controls pings on the first low-frequenc former input.

Main tuning-Condenser The main-tuning condenser, is

on the right front of the panel, ar arranged so that at can be operatei junction with two vernier conde enable two telephony stations to t By the manipulation of the switel in the centre, either station can be to without , re-tuning; even thorn may be a difference of too metres wavelengths.

14.—Vollage variations on H.F. and 1). 15.—Armstrong control switch. 16. — Filam- nt resistance for L.F. valves. 17.—Reactance-vai-iometer con- . denser. 18.—Wavelength chang- ing switch. 19.—Secondary variometer. 20.— Change-over switch to enable outside tuner to be used. 21. —Plugs for outside tuner.

i

n

:

m Another

60 61

:SijpcfPdP:gijPt^cffiLpd!PigdP5g:jp[g[gi^ijPdPdPdiP:jPigigigclPElPd£EgtSi:^

pi ■H '

5 L P

An illustrated description of

an amateur'equipped trans'

mitting and receiving station

—that of Mr. L. W. Pullman,

ofA Golders Green, London,

-n- N.W.—

■o L3

wire and the variometer with The circuit, which is shown by

fram Fig. i, is of the ordinary mtrol type. In the figure referred . variometer and B the main aerial ice. The tuned variometer is th- at c and the reactance coih at D; are choke coils. The microphone ner is shown at H,, and it will Be . 1 that in connection with this is a liver switch and also a plug to cut r out. The low- and high-tension are indicated by'ltT and HT re-

ly A feature o'f the choke is that is movable in , order to make'it

to vary the effect produced.

nsion Generator f the most interesting points aboul, smitter is the fact that the high- current is obtained from a hand- generator, made by Evershed and s, which produces a Current of lamps, at 1,000 volts with the ease. The use of this instru'ment

\S ! «

'

V.......j

k

J"1

ess Den.

obviates the trouble and expense of a motor-generator or rectifier, and Mr. Pull- man states that it gives excellent results. Change-over Switch

Another point of interest is the change- over switch, which will be observed on the

be seen on the left of the switch, places the experimental artificial aerial in cir- cuit. The round box just above contains the lightning arrester. Receiver

The receiver is a 5-valve set, having one

i

4 jh VPS

iS*1-

■«

■ m 0 %

m m

% m m

Close-up Photograph of the Apparatus

REFERENCES 1 to 5.—-Valves. 6.— H.F. transformer. 7.— , Three - way switch. 8.—Filament resist- ance for H.F. valve. 9. —Grid leak change- overswitch. 10.—Grid condenser, j i.—L. F. transformer tappings. 12.—Filament resist- ance . for detector, 13. —< H.F. variable ■ tuning" condenser-

o 06 oV- o .• Y ; o

is O iz O ft 0= D ce=: a

m ® ®

^9 yOy

REFERENCES 14.—Voltage variations on H.F. and D. 15.—Armstrong control switch. 16.—Filam-nt' resistance fcr L.F. valves. 17,.—Reactance-variometer con- denser. .18.—Wavelength chang- ing switch. i g.—Secondary variometer. 20.— Change-over switch to enable putside tuner to be used* 21 f —Plugs for ■ outside tuner. .

Fig. 2.—Key Diagram showingf-Disposition of Receiving Units.

right of -the- transmitter. The switch is H.F., one detector, and three L.F. valves! arranged, io change over aerial, earth, and low- and high-tehsiofl positive" and nega- tive, so"that when transmitting the receiver is dead. Pressure on,the white button, to

The last three valves, by an arrangement of styifches, can be converted into the Armstrong, supertregenerative" receiver, from which excellent results are obtained.

Receiving Valves From right to left on the panel

the H.F. valve with a H.F. varial transformer, and under this is th condenser. The next valve is the- and aboye it and slightly to the double-pole switch is fitted whicl: various values of grid-leaks to Below the detector valve there is variable condenser, and on the ri( is a 5-way switch, which controls pings on the first low-ffequenc former input.

Main tuning-Condenser The main-tuning condenser is

on the right front of the panel, ar arranged so that at can be operatei -junction with-two vernier conde ■enable two telephony stations to t By the manipulation of the switel in the centre, either station can be to without re-tuningy even thoui may be a difference-of too metres wavelengths.

IS

m

m

Another

Page 14: Amateur Wireless Magazine, Weekly, Sat 20th January 1923...Amateur Wireless Magazine, Weekly, Sat 20th January 1923. DONT MISS FREE MAP WITH CALL SIGNS NEXT WEEK Vol. 11, No. 33 SATURDAY,No

61 ^mateur ^/ireles5

An illustrated description of

an amateur^ equipped trans-

mitting and receiving station

—that of Mr. L. W. Pullman, In of Golders Green, London,

—N.W. J

J

Vi -V 7-

• n:

4-6 6 4- 4-6 HT l*4v. 200v. 50 V 6Y. Fig. 3.—Circuit Diagram

Lj 6 4- of Receiver.

s s i i i- •a i i i i 0 1 B Lj a

of a be seen on the left of the switch, places Pull- the experimental artificial aerial in cir- sults. cuit. The round box just above contains

the lightning arrester.

ange- Receiver n the The receiver is a 5-valve set, having one

, * .

1 -; A

m 1,

Photograph of the Apparatus

3 O

• o ."Y ■■ o 12 O 8 ,0 " 13

© 0

2 °° 1 o o

06

REFERENCES 14.—Voltage variations on

H.F. and 1). 15.—Armstrong control switch. 16.—Filam-nt resistance fcr L.F. valves. 17.—Reactance-variometer con-, denser. 18.—Wavelength chang- ing switch. 19.—Secondary variometer. 20.— Change-over switch to enable p u t s i d e tuner to be used. 21. —Plugs for outside tuner.

ihowin^ TKsposition of Receiving Units.

tch is 1, and nega- ceiver on, to

H.F., one detector, and three L.F. valves. The last three valves, by an arrangement of switches, can be converted into the Armstrong super-regenerative receiver, from which excellent results are obtained.

Receiving Valves From right to left on the panel there is

the H.F. valve with a H.F. variable-range transformer, and under this is the tuning- condenser. The next valve is the detector, and aboye it and slightly to the right a double-pole switch is fitted which enables various values of grid-leaks to be used. Below the detector valve there is another variable condenser, and on the right there is a 5-way switch which controls the tap- pings on the first low-frequency trans- former input.

Main tuning'Condenser The main-tuning condenser-is in a box

on the right front of the panel, and this is arranged so that it can be operated in con- junction with two vernier condensers to enable two telephony stations to be tuned. By the manipulation of the switch, shown in the centre, either station can be listened to- without re-tuning; even though there may be a difference of too metres in their wavelengths.

Wavemeter On the (op of the receiver and at the

extreme left the wavemeter is to be seen, which is of the well-known Townsend type. In the glass-topped case, to be seen on the left in the photographs, is a stand-by set, which ordinarily is never used, being merely kept as a standard for reference.

All the wiring is carried out with 16- gauge wire, and all condensers are sheathed in metal cases with the latter earthed. Panels are coated on the back with tinfoil, the foil being cut away where necessary to clear .parts; the tinfoil is also earthed. The same system . is carried out with the low-frequency transformers,- all these being placed in metal cases and earthed. The diagram (Fig. 2) with its accompanying references will make the disposition of the apparatus clear. A cir- cuit diagram of the receiver is shown by Fig- 3- '

Mr. Pullman considers method and neatness to be essential for really success- ful results to be obtained.

i ■ sIHI _,,w

I ; M; ■4

■F

Another Photograph of the Apparatus.

1 i i i

6 0 0

. 0 0 0 i-

1 ' . ' ■ v 0

61 ^matair ^/irelesj

An illustrated description of

an amateur'equipped trans'

mitting and receiving station

—tKat of Mr. L. W. Pullman,

of^Golders Green,, London,

—Tj N.W.—

of a be seen on the left of the switch, places Pull- the experimental artificial aerial in cir- sults. cuit. The round box just above contains

the lightning arrester, '

ange- Receiver n the The receiver is a 5-valve set, having one

i m

1

I

Photograph of the Apparatus

tt TL

3 2 O f0

-1 Jr O / Y^O 12 6 8 11 10 13

1 o

0 ®

06

m.

REFERENCES 14.—VoUage variations on

H.F. and D. 15.—Armstrong control switch. 16.—Filanviit" resistance fcr L.F. valves. 17. — Reactance-variometer con- . denser. -18.—Wavelength chang- ing switch. _ 19.—Secondary variometer. 26.— Change-over switch to enable p u t s i d e tuner to be used. 21." —Plugs for * outside tuner. v°/ ? tS;

ihowin^IXsposition of Receiving Units.

fch is 1, and nega- ceiver on, to

H.F., one detector, and three L.F. valves. The last three valves, by an arrangement of sryitches, can be converted into" the Armstrong, super-regenerative receiver, from which excellent results are obtained.

V

vS ?

. rr

+ 6 0 0+ l-OHTOLT- l-4v.200v. ev. IFig. 3.—Circuit Diagran

4- of Receiver.

Receiving Valves From right to left on the panel there is

the H.F. valve with a H.F. variable-range transformer, and under this is the tuning condenser. The next valve is the-detector, and abave it and slightly to the right a double-pole switch is fitted which enables various values of grid-leaks to be used. Below the detector valve there is another variable "condenser, and on the.right there is a 5-way switch which controls the tap- pings on the first low-frequency trans- former input.

Main tuning-Condenser The main-tuning condenser is in a box

on the right front of the panel, and this is arranged so that fit can be operated in con- junction with two vernier condensers to enable two telephony stations to be tuned. By,the manipulation of the switch, shown in the centre, either statio'n can be listened to without re-tuning; even though there may be a difference of- too metres in their wavelengths.

Waveweter On the top of the. receiver and at the

extreme left the wavemeter is to be seen, which is of the well-known Townsend type. In the glass-topped case, to be seen on the left in the photographs, is a stand-by set, which ordinarily is never used, being merely kept as a standard for reference.

All the wiring is carried out with 16- gauge wire, and all condensers are sheathed in metal cases with the latter earthed. Panels are coated on the back with tinfoil, the foil being cut away where necessary to clear partsthe tinfoil is also earthed. The same - system,is carried out. with the low-frequency transformers/ all these being placed in metal cases and earthed. The diagram (Fig. 2) with its accompanying references will make .the disposition of the apparatus clear. A cir- cuit diagram of the receiver is: shown by Fig. 3- A

Mr. Pullman considers method and neatness to be-essential for really success- ful results to be obtained.

i s % i ft

i

-

■n. ■

Another Photograph of the Apparatus.

Page 15: Amateur Wireless Magazine, Weekly, Sat 20th January 1923...Amateur Wireless Magazine, Weekly, Sat 20th January 1923. DONT MISS FREE MAP WITH CALL SIGNS NEXT WEEK Vol. 11, No. 33 SATURDAY,No

^mateur ^/i«Ics5 62 JANUARY 20 1923

Cigar-box Valve Panels

I HE advantages of a three- or four- ^ valve cabinet set are compactness and

appearance, but against these there is the disadvantage of not being able to alter the connections to enable another circuit to be used.

The writer has made, and is using with great success, a series of small one-valve panels made from cigar-boxes which can be connected together, providing both high- and (or) low-frequency amplification,

A number of cigar-boxes are obtained, the "50" size being very convenient for the purpose, having dimensions of, roughly, 9 in. by 5 in. Soak off the paper with warm water, taking care that the

heating it over a gas flame or lamp. It has to be done very carefully, as the fibre easily breaks. Bend the rod to make a semicircle of about 2 in. diameter, and then near each end make a 6B.A. clearance hole. File one side of the rod flat and wind the grooves with about No. 24 re- sistance wire, securing each end to a 6 B.A. brass bolt 54 in. long. Cut out a piece of J4j-in. ebonite about 3)4 in. by lyi, in., and in the centre drill a hole just large enough to take a piece of brass tube having an inside diameter large enough to take a 2 B.A. brass rod easily. A piece of this tube ^ in. long should be pressed into the hole in the ebonite and its edges

close to the other side of the ebonite. Brass or copper washers should be placed on the rod on each side of the ebonite to ensure easy working. Connection to the moving arm is made by soldering a strip of copper foil (about 3 in. long by Yi in. wide) to the end of the brass rod; wind a couple of turns of the foil round the rod, and solder the free end to a piece of stout copper wire, which is held down to the ebonite by a 6 B.A. bolt. This makes a positive connection.

The rheostat is secured to the supports by 6 B.A. bolts as in Fig. 3, taking care that the rod does not bind in the hole in the ebonite panel. A small knurled knob

lie , ' • GL • ' 1

• 1 1 P • 1 ' 1 1 I : 1

• 1 T.i ;

1®+ i ^ • i 1 1 — 1 > L®. ?j

GL G .p

X/TT

6 BA

■HSlsA^ -noj IwpswMjafliws

Panel

Fig. 1.—Lid of Box Cut Out.

Fig. 2.—Box with Ebonite Panels Fitted.

Fig. 4.—Wiring Diagram.

Brass Strip

/ 1CT" Ik ""Fibre Rod BrassArm 1 (g) ^ J Copper Wire

Copper Foil Fig. 3.—Enlarged Detail of Filament Rheostat.

boxes are weighted during drying to pre- vent warping, and with a fretsaw cut out the lids as shown in Fig. 1. Small brass hinges (if not already fitted) should be obtained and the lids carefully hinged.

Panels A sheet of ebonite Ys in. thick should

be obtained, and a piece % in. longer and Y in. wider than the box lid cut out. This is secufed by small brass wood screws at each corner and the middle of each side as shown in Fig. 2. Holes are now drilled to take the valve socket, terminals, and for the filament rheostat rod (this should be 2 B.A. clearance). The terminals marked are the same for all panels, with the exception of the two marked G L and x. For the rectifying valve panel the terminal GL must be put in, as this-is to be connected to a grid-leak and con- denser which is placed across terminals G L and G. If desired, the grid-leak and condenser may be cut out by connecting direct to G instead of G L. The panel to which the phones are to be connected must have a terminal T and a small blocking condenser connected across P and T.

Rheostat The filament rheostat (Fig. 3) is made

by putting a /^-in. Whit worth thread on a piece of J|-in. round fibre rod (red fibre is better than the black, as it is not so brittle) and bending the threaded rod by

burred over to hold it securely. This is to make a brass bush for the rod, which otherwise would very quickly wear the ebonite. Mount the resistance coil, flat side uppermost, on to the piece of ebonite, securing it by the two 6 B.A. bolts. Firmly fix a small strip of strong, springy brass about 1% in. long on to a piece of brass rod, screwed 2 B.A. and about 2 in. long, by means of two nuts. Put this through the bushed bole so that the brass strip makes contact with the resistance wire. Secure this rod by means of another nut

should now be fixed on the projecting rod, and as an additional refinement a pointer and scale may be fitted.

Connections General connections are shown in Fig. 4.

It will be noted that in the diagram the plate lead is connected to the lower ter- minal marked T in Fig. 2, and the H.T. phones to the upper terminal. By having all connections brought out it is apparent that any number of circuits can be tried at will. - E. A. E.

A Simple Series-parallel Device

I T is surprising to find how few people ^ realise the advantages of wiring the aerial-tuning condenser in series for the reception' of short-wave telephony. If a condenser of .001 microfarads, which is about the most usual capacity for the A.T.C., is used in parallel, it is impossible to tune down even to broadcasting wave- lengths without reducing the number of turns in the primary coils of the aerial- tuning inductance to something very small indeed; and matters become worse when it is desired to listen to amateur transmis-

sions on round about 180 metres. The in- troduction of a large capacity in parallel means that weak signals and indistinct speech come in, whilst tuning has often to be so finely done that it is most difficult to keep the set from oscillating. Even when dealing with the longer waves it will often be found an improvement to throw the condenser into series and to use a larger coil. I find, for example, that when this is done both Lympne and Le Bourget come in well enough to be heard on three valves (i H.F., 1 R., 1 L.F.) with a loud-

^mateur ^/ircles^ 62 JANUARY 20 1023

Cigar^box Valve Panels

I HE advantages of a three- or four- ^ valve cabinet set are compactness and

appearance, but against these there is the disadvantage of not being able to alter the connections to enable another circuit to be used.

The writer has made, and is using with great success, a series of small one-valve panels made from cigar-boxes which can be connected together, providing both high- and (or) low-frequency amplification,

A number of cigar-boxes are obtained, the "50" size being very convenient for the purpose, ^ having dimensions of, roughly, 9 in. by 5 in. Soak off the paper with warm water, taking care that the

heating it over a gas flame or lamp. It has to be done very carefully, as the fibre easily breaks. Bend the rod to make a semicircle of about 2 in. diameter, and then near each end make a 6B.A. clearance hole. File one side of the rod flat and wind the grooves with about No. 24 re- sistance wire, securing each end to a 6 B.A. brass bolt % in. long. ' Cut out a piece of yfa-in.. ebonite about in. by 2)^ in., and in the centre drill 'a hole just large enough to take a piece of brass tube having an inside diameter large enough to take a 2 B.A. brass rod easily. A piece of this tube ^ in. long should be pressed into the hole in the ebonite and its edges

close to the other side of the ebonite. Brass or copper washers should be placed on the rod on each side of the ebonite to ensure easy working. Connection to the moving arm is made by soldering a strip of copper foil (about 3 in. long by in. wide) to the end of the brass rod;' wind a couple of turns of the foil round the rod, and solder the free end to a piece of stout copper wire, which is held down to the ebonite by a 6 B.A. bolt. This makes a positive connection.

The rheostat is secured to the supports by 6 'B.A. bolts as in Fig. 3, taking care that the rod does not bind in the hole in the ebonite panel. A small knurled knob

fo • GL

/f*

r.-i"

i ■ : 1 T*:! 1®+ ih. •! '

1 1 1 • « 1 t— 1 >

w t t — 1 t «•;; L®_ r::

^ GL

-T

'"-At

Panel

6 BA Brass Strip . ■0./V>r

•spoaiai^K*.

Fig. 1.—Lid of Box Cut Out.

Fig. 2.—Box with Ebonite Panels Fitted.

Fig. 4.—Wiring Diagram.

/ TU |L ~ "Fibre Rod Brass Arm 1 ^ ^ J Copper Wire

Copper Foil Fig. 3.—Enlarged Detail of Filament Rheostat.

boxes are weighted during drying to pre- vent warping, and with a fretsaw cut out the lids as shown in Fig. 1. Small brass hinges (if not already fitted) should be obtained and the lids carefully hinged.

Panels A sheet of ebonite Yz in. thick should

be .obtained, and a piece ^ in. longer and %■ in- ^'ider than the box lid cut out. This is secured by small brass wood screws at each corner and the middle of each side as shown m Fig. 2. Holes are now drilled to take the valve socket, terminals, and for the filament rheostat rod (this should be 2 B.A. clearance). The terminals marked are the same for all panels, with the exception of the two marked G L and T. For the rectifying valve panel the terminal ,GL must be put in, as this""is to be connected to a grid-leak and con- denser which is placed across terminals G l and G. If desired, the grid-leak and condenser may be cut out by connecting direct to G instead of G L. The panel to which the phones are to be connected must have a terminal T and a small blocking condenser connected across P and T.

Rheostat The filament rheostat (Fig. 3) is made

by putting a J^-in. Whitworth thread on a piece of '^-in. round fibre rod (red fibre is better than the black, as it, is not so brittle) and bending the threaded rod by

burred over to hold it securely. This is to make a brass bush for the rod, which otherwise would very quickly wear the ebonite. Mount the resistance coil, flat side uppermost, on to the piece of ebonite, securing it by the two 6 B.A. bolts. Firmly fix a small strip of strong, springy brass about 1% in. long on to a piece of brass rod, screwed 2 B.A. and about 2 in. long, by means of two nuts. Put this through the bushed hole so that the brass strip makes contact with the resistance wire. Secure this rod by means of another nut

should now be fixed on the projecting rod, and as an additional refinement a pointer and scale may be fitted.

Connections General connections are shown in Fig. 4.

It will be noted that in the diagram the plate lead is connected to the' lower ter- minal marked T in Fig. 2, and the H.T. phones to the upper terminal. By having all connections brought out it is apparent that any number of circuits can be tried ■at will. - E. A. E.

A Simple Series-parallel Device

T T is surprising to find how few people ^ realise the advantages of wiring the aerial-tuning condenser in series for. the reception' of short-wave telephony. If a condenser of .001 microfarads, which is about the most usual capacity for the A.T.C., is used in parallel, it is impossible to tune down even to broadcasting wave- lengths without reducing the number of turns in the primary coils of the aerial- tuning inductance to something very small indeed; and matters become worse when it is desired to listen to amateur transmis-

sions on round about 180 metres. The in- troduction of a large capacity in parallel means that weak signals and indistinct speech'come in, whilst tuning has often to be so finely done that it is most difficult to keep the set from oscillating. Even when dealing with the longer'waves it will often be found an improvement to throw the condenser into series and to use a larger coil. I find, for example, that when this is done both Lympne and Le Bourget come in well enough to be heard on three valves (t H.F., 1 R., 1 L.F.) with a loud-

Page 16: Amateur Wireless Magazine, Weekly, Sat 20th January 1923...Amateur Wireless Magazine, Weekly, Sat 20th January 1923. DONT MISS FREE MAP WITH CALL SIGNS NEXT WEEK Vol. 11, No. 33 SATURDAY,No

JANUARY 20, 1923

speaker; whilst if the condenser is in parallel a second L.F. valve must be used to make their speech plainly audible.

One of the strongest reasons for fitting some device which enables one to change over quickly from parallel to series is that it enormously increases the range of basket, slab, or honeycomb inductances.

63 A.T.C. itself, .and it costs next to nothing to make. Also, it is a job that anyone can do in little more than half an hour.

Between the existing terminals on the ebonite top of the condenser fit two more a and h (Fig. i), placing them so that the four are evenly .spaced. Now take' three straps of the shape shown in Fig. 2, using

^moteur ^/irelesj

©

©

(M)

y y

%

Fig. 1.—The A.T.C. with Extra Terminals Fitted.

0£ 3 Fig. 2.—Connecting Hook.

M

Fig. 3.—The Condenser in

Series.

Fig. 4.—The Con- denser in Parallel.

If a coil will tune from 1,000 to 2,000 metres with the condenser in parallel, its range with the condenser in series may be something like 500 to goo. metres. This means that with one small gap a single coil can be made to . cover all wavelengths from 500 to 2,600 metres. The size of the gap between series and parallel depends largely upon the capacity of the aerial. The thinner its wires and the less there are of them the smaller the " dead spot " will be. In any case, it is nothing very great, and it can be done away with alto- gether if a small vernier condenser is kept permanently wired in parallel.

The commonest way of making a series- parallel change device is to use a double- pole double-throw switch of some kind. This is a perfectly satisfactory arrange- ment, but the means outlined here of accomplishing the desired end will be found still better. It is mounted on the

sheet brass, or even tin if brass is not available. Their length will depend on the distance between the terminals.

The lead-in is taken directly to the terminal connected with the fixed plates F (Fig. 1), the earth wire goes to 6, and the primary coil is wired to the moving-plate terminal M and to a.

A glance at Figs. 3 and 4 will show how the hooked strap? are operated. If the middle one is connected up whilst the upper and lower ones are free, the con- denser will ba wired in series; the reverse of this arrangement puts it in parallel.

This change can be made in a moment, for the primary coil need not be discon- nected. The vernier condenser, if one is used, should be connected to terminals F and M. Its use will be found to facilitate considerably the critical adjustments necessary for very short-wave reception.

R. W. H.

pdp[g[tp[1p[rp[jp[jpdp[jp[ffl[g[jp[jp[tpclpcgtcg3[gj[ 1

Details of Loose-coupler with Dead-end Switch.

thereby permitting ia much better tuning arrangement with increased volume of sound. By opening the single-pole knife switch, indicated in the drawing, the un- used portion of the primary coil from the aerial circuit is disconnected.

With a coil of this kind any desired wave range may be obtained from zoo to 2,000 metres by simply varying the number of turns of wire out into the circuit with the circular disc switch. The minimum number of turns to be wound on the coil prior to tapping in the single pole switch would be fifty-five. This permits the re- ception of signals from transmitting stations of 400 metres and less. For re- ception of signals of over 400 metres wave- length, the minimum number of turns should be 150. Taps should be taken from the remainder of the coil at intervals of turns, and fastened securely to the contact points of the circular disc switch.—Radio N ews.

1 Loose-coupler with Dead-end Switch! % _ . , i

THERE is a certain amount of current cuit and signals in the receiver. By means in the unused balance of the primary of the dead-end switch, as shown in the

coil of a loose-coupler which is not in accompanying sketch, any portion of the

resonance ■ with the aerial, that is not unused coil may be cut entirely out of the only a total loss in the secondary circuit, circuit. The unused turns are ^ short-cir- but which acts to retard the secondary cir- cuited by means of the circular disc switch,

I Radiograms ii 01

QtPiSiflPijiiipdPcfpiJPdPdPdPifPdPdPdPdlPdPiiPaPdFQ SOME alterations have been effected in

the aerial of the London broadcasting- station which have considerably increased its range. Amateurs whose apparatus has heretofore been just beyond the. range of 2 L O may now be able to get some, results.

It is hoped that Cardiff broadcasting station will be ready to start work by the time this issue of AMATEUR WIRELESS is in the readers' hands. The Glasgow station, we learn, ought to be completed by Jan. 25.

BUB

We hear from the Sterling Telephone and Electric Company, Limited, that this firm has opened a branch at 14, St. Peter's Square, Manchester, for dealing with! orders from Lancashire, Yorkshire, Cheshire, and Derbyshire. Facilitiesi have been provided for daily demonstra-i, tions of wireless apparatus.

The call sign of the Birmingham broad- casting station has been altered from 2 W PJ to 5 I T.

B ■ ■ Whilst a film was being shown in.,

America explaining the working of thei three-electrode valve a lecturer accom- panied the film with a running com- mentary on it. Soon the audience discovered that the lecturer was sitting silent among them, and it was then ex-i plained that he had delivered the same lecture in New York several days before, his words being recorded by an electrical device.

JANUARY 20, 1923

sp.eaker.; wbilst; if itfie condenser is in parallel a second L.F. valve must be used to make their speech plainly audible.

One of the strongest reasons for fitting some device which enables' one to "change over quickly from parallel to series is that it enhrmbusly- increases the range of basket, slab, or honeycomb inductances.

63 A.T.C, itself, .and it costs next to nothing to make. Also, it is a job that anyone can ,do in little more than half an hour.

Between the existing terminals. on the ebonite top of the condenser fit two more a and b (Fig. 1), placing them so that the four are evenly ispaced. Now take'three straps of the shape shown in Fig. 2, using

^motcur ^/irclcs5

©

©

Fig. 1.—The A.T.G. with Extra Terminals Fitted.

Q£. J Fig. 2.—Connecting Hook.

Fig. 3.—-The Condenser in

Series.

Fig. 4.—The Con- denser in Parallel.

If a coil will tune from 1,000 to 2,000 metres with the condenser in parallel, its range with the condenser in. series may be something like 500 to goo. metres. This means that with one small gap a single coil can be made to.cover all wavelengths from 500 to 2,600 metres. The size of the_ gap'between series and "parallel depends' largely upon the capacity of the aerial. The thinner its wires and the _ less there are of them the smaller the " dead spot " will be. In any case, it is nothing very great, and it can be done away with alto- gether if a small vernier condenser is kept permanently wired in parallel.

The commonest way of making a series- parallel change, device is to use a double- pole doublehhrow switch of some kind. This is a perfectly satisfactory arrange- ment, but, the means outlined here of accomplishing , the desired end will be found still better.. It is mounted on .the

sheet brass, or even tin if brass is not available. Their length will depend on the distance between the terminals.

The lead-iri is taken directly to the terminal connected with the fixed plates F (Fig. x), the earth wire goes to bj and the primary coil is wired to the moving-plate terminal M and to a. -

A glance at Figs. 3 and 4 will show how the hooked straps are operated. If' the middle one is connected up whilst the upper and, lower ones are free, the con- denser will be wired in series; the reverse of this ari'angement puts it in parallel.

This change can be made in a moment, for the primary coil need not be discon- nected. The vernier condenser, if one is used, should be connected to terminals ,F and M. Its use will be found to facilitate considerably the critical adjustments necessary for very short-wave reception.

R. W. H.

[Loose-coupler with Dead-end Switch!

THERE is a certain amount of current cuit and signals in the receiver. By means in the unused balance of the primary of the dead-end switch, as - shown in the

coil of a loose-coupler which is not in accompanying sketch, any portion of the

resonance with the. aerial, that is not only , a totaMoss in the secondary circuit, but which acts to retard the secondary cir-

Detalls of Loose-coupler with Dead-end Switch..

unused coil may be cut entirely out . of the circuit. The .unused turns are short-cir- cuited by means of the circular disc.switch,

thereby permitting a much better tuning arrangement with increased volume of sound. By opening the single-pole knife switch, indicated in the drawing, the un- used portion of the primary coil from, the aerial circuit is disconnected.

With a coil of this kind 'any desired, wave range may be obtained from 200 to 2,000 metres by simply varying the number of turns of wire out info the circuit with the circular disc switch. The minimuiri number of turns to be wound on the coil prior to tapping, in the single pole switch would.be fifty:fiye. This permits the re-, ception of signals from transmitting stations of 400 metres and less. For re- ception of signals of over 406 metres wave- length, ' the minimum number of turns should be 150. Taps should be taken from the remainder of the coil at intervals of turns, and fastened securely to the contact points of the circular disc switch.—Radio N ews.

Radiograms

SOME alterations have been effected in the aerial of the. London broadcasting,

station which have considerably increased its range. Amateurs whose apparatus has heretofore been just beyond the,.range of 2 L O may now be. able to get some, results.

It is hoped that Cardiff broadcasting station will be ready to start work by the. time this issue of Amateur Wireless is in the readers' hands." The Glasgow station, we learn, ought to be completed by. Jan. 25.

b a a

We hear from the Sterling Telephone and Electric Company, Limited, that this' firm has opened a branch at 14, St. Peter's Square, Manchester, for dealing with! orders from Lancashire, Yoi'kshire,; Cheshire, and Derbyshire. Facilities! have been prbvided for daily demonstra-i tions of wifeless apparatus.

The call sign of the Birmingham broad- casting station has been altered from 2 W P,1 to 5 I T.

a h a

Whilst a film Was being shown in.( America explaining the working of the' three-electrode valve a lecturer accom- panied the film with a running com- mentary on it. Soon the audience discovered that the lecturer was sitting silent among them, and it was then ex- plained that he had delivered the same lecture in New York several days before, his words being recorded by an . electrical device.

Page 17: Amateur Wireless Magazine, Weekly, Sat 20th January 1923...Amateur Wireless Magazine, Weekly, Sat 20th January 1923. DONT MISS FREE MAP WITH CALL SIGNS NEXT WEEK Vol. 11, No. 33 SATURDAY,No

mateur l^irelesj

A very successful innovation was the- broadcasting of selections of the "Magic Flutey' grand opera, on the night of Jan, 8. The selections were sent from Covent Garden by means of a special cable and micropbon® placed, in front of the orchestra, to ■ Marconi House, from whence it was broadcast.

The deputation of the Empire Press Union which waited oil the P.M.G. on Jan. 8 were unable to get much satisfac- tion regarding the Empire wireless system. The P.M.G. was able to state that the Government were reconsidering the whole question, but it had not been decided where the money for the new station was to come from, or what sbte it was to be.

■ ■ a

The Canadian Marconi Company have decided to build a new station in Van- couver, the cost of which, when completed, is expected to be in the neighbourhood of 2,000,000 dollars.

The staff of the Metropolitan Water Board have decided to form a wireless club, and have planned to install a 6- valve receiving set.

A group of medium-power wireless stations employing valve transmitters has been erected by Marconi's Wireless Tele- graphy Company, Limited, at North Weald, near Ongar, Essex, for the pur- pose of conducting commercial wifeless services with F ranee, Switzerland, and Spain.

These stations have .been brought to a high state of. efficiency.; Although only designed for European communication one of them has been carrying on a Trans- atlantic service to , Canada. One of the other stations (G L O), which is used for communication with Madrid, a distance of about 720 miles, can be heard at Ban- doeng, Java, 7,50° miles distant.

An amplifier, using a 60-cycle A.C. supply for anodes and filaments, has- been developed by the Bureau of Standards, U.S.A. It has three stages of H.F. ampli- fication, a crystal rectifier, and two note magnifiers.,

BBS Dr. Franklin Leroy Satterlee, an

American X-ray specialist, has invented a non-regenerative set, which makes one detecting valve do the work of two stages of high-frequency amplification.

a n a With a two-valVe set Manchester tele-

phony has been heard so clearly in Glas- gow that the indrawing of the announcers breath was quite audible, also the open- ing and closing of switches at the trans- mitting1 'station.

64

The Italian-American Association gave a reception in Rome to Senator Marconi on Dec. 28, the twentieth anniversary of wireless telegraphy.

An American (Nebraska) is suing for an injunction to; break up an alleged monopoly of the ether by the American wireless companies.

One of the latest American productions is a receiver comprising a 2-valve set,

A Gift with Next Week's ISSUE OF

"Amateur Wireless □ ================= □ 3 " WIRELESS TRANSMITTING STATIONS 3 AND THEIR CALL SIGNALS" -)j is the title of a sheet which we shall present gratis j— M with next week's " Amateur Wireless." You will get rf =H your copy of" Amateur Wireless "—a Special Broad- H: T) casting Number by the way, containing many extra rr T] pages—and with it you will receive this special pre- r.; H sentation sheet, all for tbe usual price ot three- ff 0 pence. The sheet alone is worth twice the amount. 0 □ " Wireless Transmitting Stations and their E 0 Call Signs" will be printed in two colours on E □ special paper; the paper has been specially chosen so E □ as to ensure permanency, the Idea being that the E El sheet can be hung up on the wall alongside the E E receiver. The sheet has two .great features : one, E □ a Map showing the Positions of Most of the [• □ Transmitting Stations in England, and the other F □ the fullest possible List of Transmitting E 0 Stations—amateur and otherwise—that it has been E 0 possible to compile. The printed portion of the E 0 sheet measures no less than 22 in. by 22% in., and E 0 readers can be a sured of the extraordinary value 0 0 which we have packed tight within those limits, E 0 Editorially, next week's "Amateur Wireless" will == 0 appeal to the many thousands of people attracted by Ul the new broadcasting and desirous of becoming 0 wireless amateurs. The articles have been specially 0 wiitten to help and encourage them. Practical, in- 0 formative, up-to-date, well illustrated, we promise our 0 readers that the Special Broadcasting Number of 0 "Amateur Wireless," to be published next week, 0 will give them unstinted pleasure. 0 Will amateurs generally pass the good word along ? 0 Will they explain to any friends who contemplate be- ^ 0 coming either amateurs or merely "Hsteners-in" 0 0 that their best possible guide is " Amateur t 0 Wireless"? Next week's issue will be a splendid'-1

0 one for the new reader to start with. We trust that 0 we can rely upon the kindness of the constantly 0 growing number of our readers to put in a good 0 word for us- between now and next week. News- 0 agents and bookstalls will be carrying extra sup- 0 plies of " Amateur Wireless." (We apologise, by T] the way, for any trouble there has been in recent T] weeks in obtaining copies of this paper. Twice we 0 have been quite out of>print.)_ Will all our readers 0 register their orders with their newsagent or book- 0 stall for a regular weekly copy, and will they, in 0 addition, do us the great favour of suggesting ,E 0 to their friends that they also become^ 0 regular subscribers. 300B0BEEQBQQ0B000QB0QBHH0HE10B

frame aerial, batteries, and loud-speaker, which is all contained in a suit-case, and can bo operated anywhere.

CORRESPONDENCE.

Minus the H.T. Battery SIR,—On January 4th I received the

2 L O concert on the detector valve (Mullard "Ora") with 3.5 volts L.T. and without any high-tension supply. Is (his unusual? My set is a 4:valver made to your specifications—1 detector, 1 tuned

JANUARY 20, i923

anode, and 2 L.F. with short-wave loose- coupler tuner.—A. T. N. (Thornton Heath).

A Seven-hours' Concert and French Transmissions

Sir,—Of course seven hours of un- jammed and uninterfered-with reception is not possible every night of the week : but your correspondent G. T. (Bromley) must be very unlucky if the sample of a night he gives in the issue of January 13 is usual with him, as he seems to suggest it is. Perhaps his set is not nearly so selective as regards its tuning arrange- ments as it might be. It may be said that since the article which G. T. refers to was written the writer has beaten its record with almost untroubled receptions of nine and ten hours on a Sunday, start- ing with Radiola at 2 p.m. and ending with the amateurs when the broadcasting stations had closed down.

By the way, the correspondent who wishes to know what French transmissions he has been listening to can see by refer- ence to your list of regular transmissions. The occasional 5 p.m. to 6 p.m. transmis- sion is from Concerts Radiola, Paris. The one that ends at seven o'clock is from Eiffel Tower on 2,600 metres. Radiola always works from 9.45 p.m. to 10 p.m. or just after, and Eiffel Tower is sometimes on in the evening as well. Radiola is on 1,500 metres. If Radiola or Eiffel Towci are jammed or accompanied by much crackling, try cutting out reactance if it is being used.—E. L. (Pirbriglit).

Re-radiation Sir,—Almost every evening one hears

2 L O repeat complaints from various dis- tricts regarding the misuse of reaction and other annoyances. Suffering very much from this disease myself, I have been working on the matter for some time. Result ; Living about six miles from the Strand, I have received 2 L O each evening for the last month with » single valve and a frame aerial 13 in. square. A two-valve amplifier is attached and can be switched in if required, but the second valve of the amplifier has never been necessary. Writtle can be heard right through, and Birmingham is audible with the second amplifier valve. Users of outside aerials do not "realize what pleasure it is to re- ceive the news and concerts without the usual accompaniment of scratches, screams, etc. If any fellow sufferer is interested and can construct his own tuner I shall be very pleased to send you details. There is nothing more serious to make than a single-layer coil, so almost anyone can construct the instrument and rid them- s' elves of the nuisances caused by the many ignorant knob twisters.—F. T. C. (Streatham).

[AVe shall be' glad to have the par- ticulars offered.—Ed.]

A taxi-cab company in Paris has applied for permission to fit its vehicles with receiving apparatus.

^matcur ^irclesj 64 JANUARY 20, 1923

A very successful innovation eras, the^ broadcasting of selections of tfie "Magic Flute,1' grand opera, on the night of Jan. S. The selections' were, sent from. Cdvent Garden by means .of a special, cable and micrdphon©- placed in froht of' the orchestra, to ■ Marconi House, from whence it was broadcast.

The deputation of the Empire Press Union "which waited oil the P.M.G. on Jan. 8 were unable to get much satisfac- tion regarding the Empire wireless system. The P.M.G. was able to state that the Government were reconsiderihg the whole question, but it had not been decided where the money for the new station was to come from, or. what size it was to be.

■ ■ H

The Canadian Marconi Company have decided to build a new station in Van- couver, the cost of which, when completed, is expected to'be in" the neighbourhood of 2,000,000 dollars.

B B •

The staff of the Metropolitan Water Board have decided to form a wireless club, and have planned to install a 6- valve receiving set. , ,

A group of medium-power 'wireless stations employing valve transmitters has beeh erected by Marconi's "Wireless Tele- graphy Company, " Limited, at North Weald, near. Ongar, Essex, for the pur- pose of conducting commercial wifeless services with France, Switzerland, and Spain.

These stations have .been brought to a high state of, efficiency. Although only designed for European communication one of them has been carrying on a Trans- atlantic service to , Canada. .One of the other stations (G L O), which is used , for communication with Madrid, a distance of about 720 miles, can be heard 'at Ban- doeng, Java, 7,500 miles distant.

An amplifier, using a 60-cycle A.C. supply for anodes and filaments, has- been ■ developed by the Bui'eau of Standards, U.S.A. It has three stages of H.F. ampli- fication, a crystal rectifier, and two note magnifiers-

b a ■ Dr. Franklin Leroy Satterlee, an

American X-ray specialist, has invented a non-regenerative set, which • makes one. detecting "valve do the, work of two stages, of high-frequency .amplification.

With a two-valve set Manchester tele- phony has ■been-heard so clearly in" Glas- gow that the indrawing of the announcer's breath was quite audible, also the open- ing and closing- of switches, at the trans- mitting* 'elation:

The Italian-American Association, gave a reception in Rome to Senator Marconi On Dec. 28, - the twentieth- -anniversary of wireless, felcgraplly.

An American (Nebraska) is suing for an injunction to- break tip an- alleged monopoly of the ether by the American wireless companies.

One of the latest American productions is a receiver comprising a 2-valvc set,

300HQ00E]0l300m0H00Q0Q00[IlHH!

A Gift with Next Week s ISSUE OF-

"Amateur Wireless

3 " WIRELESS TRANSMITTING STATIONS AND THEIR CALL SIGNALS"

is the title, of a sheet which we shall present gratis with next week's " Amateur Wireless." You will get your copy of" Amateur Wireless"—a Special Broad- casting Number by the way, containing many extra pages—and with it you will receive this special pre- sentation sheet, all for the usual price of three- pence. The sheet alone is worth twice the amount.

Wireless Transmitting Stations and their 3 Call Signs" will be printed in two colours on special paper; the paper has been specially chosen so as to ensure permanency, the Idea being that the sheet can be hung up on the. wall alongside the

receiver. The sheet has two .great features : one, a Map showing the Positions of Most of the Transmitting stations in England, and the other the fullest possible List of Transmitting Stations—amateur and otherwise—that jt has been possible to compile. The printed portion of the sheet measures no less than 22 in. by 22| in., and readers can be a'sured ol the extraordinary value which we have packed tight within those limits.

Editorially, next week's "Amateur Wireless" .will =| appeal to the many_thousands of people attracted by ^ the new -broadcasting and desirous of becoming

wireless amateurs. The articles have been specially wiitten to help and encourage them. Practical,, in- r= formative,, up-to-date, well illustrated, we promise our ^ == readers that the Special Broadcasting Number of ^ " Amateur Wireless, to be published next week, will give, them unstinted pleasure.

Tj Will amateurs^generally pass the good word along? " Will they explain to any friends who contemplate be-

coming either amateurs or merely "listeners-in" that their best possible guide is " Amateur Wireless"? Next week's issue will be a splendid one for the new reader to stare with. We trust that we. can x*ely upon the kindness of. the constantly growing number of our readers to put in a good word for us* between now and next week. News- agents and bookstalls will be carrying extra sup- plies of "Amateur Wireless." (We apologise, by the way, for any trouble there has been in recent weeks in obtaining copies^ of this paper. Twice we have been quite out of print.^ Will all our readers register their orders with their newsagent or book- stall for a regular weekly copy, and will they, in addition, do us the great favour of suggesting to their friends that they also become regular subscribers.

QSBSQ00aSSQQQ00QSSQQBQE!QBI]00

frame aerial3 batteries, and loud-speaker, which is rail contained in a suit-case, and * can be operated anywhere.

CORRESPONDENCE.

Minus the H.T. Battery Sir,—On j'amiaiy 4tli I received the

2 L O concert on the detector valve (Mullard "Ora") with 3.5 volts L.T. and without any' high-tension supply. Is this unusual P ' My set is 4-valver made to • your ■ specifications—1 detector, 1 tuned

anode, and 2 L.F with short-wave loose- coupler tuner.—A. T. N. (Thornton Heath).

A Seven-hours' Concert and French Transmissions

Sir,—Of course seven hours of -un- jammed and uninterfered-with reception is not possible every night of the week : but your correspondent G. T. (Bromley) must be very unlucky if the sample of a night he gives in the issue of January 13 is usual with him, as he seems to suggest it is. Perhaps his set is not nearly so selective"1 as regards its tuning arrange- ments as it might be. It may be said that since the article which G. . T. refers to was written the writer has beaten its record With almost untroubled receptions of nine and ten hours on a Sunday, start- ing with Radiola at 2 p.m. and ending with the amateurs when the. broadcasting stations had clbsed down.

By the way, the correspondent who wishes to know what French transmissions he has been listening to can see by refer- ence to your list of regular transmission5. The occasional 5 p.m. to 6 p.m.. transmis- sion is from Concerts Radiola, Paris. The one that ends at seven o'clock is from Eiffel Tower on 2,600 metres. Radiola always works from .9)45 p.m. to to p.m. or just after, and Eiffel Tower is sometime; on in the evening as well. Radiola is on 1,500 metres. If Radiola or Eiffel Tower are jammed or accompanied by, much crackling, try cutting out reactance if it is being used.—E. L. (Pirbright).

Re-radiation Sir,—Almost every evening one hears

2 L O repeat complaints from various dis- tricts regarding the misuse of reaction and other annoyances. Suffering, very much from this disease" myself," I have been working on the matter for some time. Result : Living about six miles from the Strand, I have received 2 L O each evening for the last month with tr single valve and a frame aerial 13 iti-. square. A two-valve amplifier is attached and can be switched in if required, but the second valve of the amplifier has never been necessary. Writtle can be heard right through, and Birmingham is audible with the second amplifier valve. Users of outside aerials do" not "realize what pleasure it is to re- ceive the news and concerts without the usual accompaniment of scratches, screams, etc. If any fellow sufferer is interested and can construct his own tuner I shall be very pleased to send you details. There is nothing more serious to make than a single-layer coil, so almost anyone can construct the instrument and rid them- orelves of the nuisances caused by the- many ignorant knob twisters.—F. T. C. (Streatham).

[We shall be' glad to have the par- ticulars offered.—Ed.]

A taxi-cab company in"Paris has applied for permission to fit its" vehicles with receiving apparatus)

Page 18: Amateur Wireless Magazine, Weekly, Sat 20th January 1923...Amateur Wireless Magazine, Weekly, Sat 20th January 1923. DONT MISS FREE MAP WITH CALL SIGNS NEXT WEEK Vol. 11, No. 33 SATURDAY,No

JANUAKV 20, 1923 65 ^rrvotfcur ^irelcs^

fiS

I

Svtc^

CONTENTS

1. Crystal Detector Circuits

2. Single--Valve Circuits 3. Two-Valve Circuits 4. Three-Valve Circuits 5. Four-Valve Circuits 6. Five-Valve Circuits 7. Local Oscillators for

Heterodyne Re- ception of CW

8. Valve Transmitter and Radio Phone Circuits

^Z^^lwhich

will pass the PMC

THE use of Reaction gives almost the additional strength of another Valve, but carelessly used it is a source of great annoyance to all other re-

ceiving stations within two or three miles. Therefore the P.M.G. has rightly banned all reaction coupled to Aerial circuits on broadcast wave-lengths. No need to cut it out altogether though, for in this new book by John Scott-Taggart—that eminent authority on Thermionic Valves—several circuits are shown for the first time which permit the fullest use of Reaction which cannot cause oscillation in Jhe Aerial circuit. If you are not now using Reaction, get this book and see how easily you can alter your wiring to obtain that maxi- mum of efficiency so essential if you are to pick up those long distance broadcasting Stations. Every diagram is clearly drawn, all necessary condenser values are given—further you have the assurance that every circuit has been tried and tested, that they are not mere "paper circuits." You'll need this book to understand your Set better. Get it to-day.

Stladia Tvcss.-Cld PUBLISHERSOF AUTHORITATIVE WIRELESS LITERATURE DEVEREUX COURT. STRAND. W.C.2.

4 LnJvlMcrfiOTi

ACCUMULATORS 4 volt 20 amp. ... 14/- 6 volt 20 amp. ... 22/- < 4 „ 40 ,, ... 19. 6 „ 40 „ ...27/6 4 „ 60 „ ... 27/- 6 „ 60 „ ... 37/6 \ 4 „ 80 „ ... 33/- 6 „ 80 „ ... 52 -

(Carriage Paid) (Carriage Paid) \ These accumulators are brand new, guaranteed and j i) specially recommended. Terms Cash with Order.

;} BASTONES, 228, PENTONVIILE RD., KING'S CROSS. LONDON. Hj j

JUST PUBLISHED

THE "READY ETK00 OF EM0RISING 0RSE.

whole Alphabet can be memorised permanently in 5 MINUTES

Price 6d., or by post 6Td. R. F. ROBERTS, 3 George St., Croydon, Wholesale: Percival Marshall & Co., 66, Farringdon St., F.C.

SriFNTIFIf APPIIANfF^ Oale & Hollins). Electrical, Magnetic autrmriL ArruAhtEo 0ptical and Al4ll radio wire- less PARTS and Materials at Lowest Prices. Cail and see our immense stock or write for Information and Prices. In Centre oj London, Top of Kings-way.

SCIENTIFIC APPLIANCES, 11 and 29, Sicilian Avenue, London, W.CM.

PORTLAND'S PARTS BY POST

EBONITE

8 X i 4X4 17 X 5^ io X 6 7 X 5

s. d. & s. d. 7 12 X 10 ... 7 6 ... 1 3 17IX 8^ ... ... 9 6 ... 6 8 18 X 18 ... 12 IO ... 3 9 36 X ]8 ...1 3 O ... 2 8 7 lb. ...1 3 O

Quarter, Mat, BRITISH Postage Free— -Any Size Cut

JAMES PORTLAND, 39. SINCLAIR ROAD. OLYMPIA, W.14 N.B. Mr. Portland Stocks 200 "Wireless Parts

AT

HALL'S

PRICES THAT SPEAK

FOR THEMSELVES

BRITISH HEADPHONES 4,000 ohms. Very ' Light. Beautifully Finished. Stalloy Diaphragms. Complete with Cords. Adjust-

able Earpieces. (Sold elsewhere almost exclusively at 35/-.)

19/6 Postage 9cl. THE WELL-KNOWN French "Brunet" Headphones

22/6 POSTAGE 9d. French " Sidep " Headphones

21/- POSTAGE 9d.

GUARANTEED COODS DESPATCHED BY RETURN

VARIABLE CONDENSERS: Capacity.

.001

.0075

.0005 .0003

.0002

.0001

Parts Complete. 7/- 5/9 ... 5/- 3/3 2/3 2,'-

Assembled for Panel Mounting. ... 12/6 ... 12/- ... 10/6 ... 7/6 ... 6/-

4/9 Top and Bottom Circular Drilled Ebonite Plate, 1/6 extra. Vernier, 3/-, assembled. Intervalve Transformers, Ratio 4. to 1. finest

manufacture, 12/9; 5 to 1 14/6 Crvstal Sets from 15/- to £3 "Royal Phone" Loud Speakers, 4,000 ohms resistance, ebonite horn, giving clarity of

tone and freedom from distortion. each 30/- Orders in strict rotation. Aluminium Condenser Vanes, fixed and moving,

22/24 gauge ... pair Id- Spacers, true to .001. Small, doz. 2d.; large doz. 3dh Ebonite Knobs, tapped 2 B.A. with brass nut- Is t quality, 4d.; 2nd quality 2(\

Aerial Wire, 7/22 hard drawn copper, in 100 ft. lengths 2/5 Valve Legs, with .nuts and washers, Id. each; doz. 9d.

Two Coil Holders, solid ebonite mounted on mahogany 4/9 Three Coil Holders, solid ebonite, with long

arms to avoid capacity effects 9/6 Crystal Detectors, adjustable in every way 2/6 ditto, ditto, enclosed in glass case 4/6

Engraved Ivorine Scales, 0—180 45d. Filament Resistances, extraordinary value, velvet action ... 2/6 and 3/6 Switch Arms, complete with knob, _ collar, washers, bush nuts, etc. 1st quality, 1/6* 2nd quality _ ... 1/- Valve Holders, turned ebonite, complete with nuts, 1/3; 2nd quality 9d. Crystal Cups. Plain Id. ? one, two, or three screw _ 3d.

Large Terminals, complete with nut and washer Id. Basket Coils, set^ of 7 ... ... 5/- Contact Studs, I in. by I in., complete with nut

and washer doz. Gd. Insulators, 2-in. reels— Id. each; white egg, 3d.; green egg, 4d.; green shell each 4d.

Brass Nuts, 2,3,4,5,6 B.A., doz. 3d. Washers, doz. ... 2d. Ebonite Sheet, A, J, t Ib. til- Fixed Condensers, any capacity each 1/3 Grid Leak and Condensers combined ... each 3/6 Slider Plunger, complete each 4d. Slider Rods, 12-in. or 13-in. ^-in. square brass,

drilled both ends 4d. Hertzite, 1/6. Bornite, Carborundum, Galena 4d. Screwed Brass Lengths, 12-in. 2 or 4 B.A. each 3d. Inductances, wound 22/24 enamelled wire, each 3/3

Orders under 30/- kindly remit ample post- age. Balance refunded if excess sent. Send for Free Catalogue

TRADE IJAf 1 >0 DISPATCH SUPPLIED HALL BY RETURN ' H O 3V E : R E <3-E UXT T 12S3 71, 71a, Beak St., Regent St., London, W.l

Between Piccadilly Circus and Oxford Circus 'Buses 3, 6, 12, 13, 15, 32, 51, 59, bb, aild 88 pass

JANUARY 20, 1923 65 ^moteur ^ireley

ovBls m

CONTENTS

1. Crystal Detector Circuits

2. Singlc-'Valve Circuits 3. Two^Valve Circuits 4. Three-Valve Circuits 5- Four^Valve Circuits 6. Five'Valve Circuits 7. Local Oscillators for

Heterodyne Re' ception of CW

8. Valve Transmitter and Radio Phone Circuits

.whic/

will pass the PMC

THE use of Reaction gives almost the additional strength of another Valve, but carelessly used it is a source of great annoyance to all other re-

ceiving. stations within two or three miles. Therefore the P.M.G. has rightly banned all reaction coupled to Aerial circuits on broadcast wave-lengths. No need to cut it out altogether though, for in this new book by John Scott-Taggart—that eminent authority on Thermionic Valves—several circuits are shown for the first time which permit the fullest use-of Reaction which cannot . cause oscillation inJhe Aerial circuit. If you are not now using Reaction, get this book,and see how easily you. can alter your wiring to obtain that maxi- mum of efficiency so essential if you are to pick up those long distance broadcasting Stations. Every diagram is clearly drawn, all necessary condenser values are given—farther you have the assurance that every circuit has been tried and tested, that they- are not mere "paper circuits," You'll need this book to understand your Set better. Get it to-day.

illadia "ii'vess. Uld PUBLISHERS OF AUTHORITATIVE WIRELESS LITERATURE DEVEREUX COURT. STRAND. W.C.2.

%j> } ckfmJjcMi LnJolMation.

ACCUMULATORS 4 yolfe 20 amp. 14-/. 4 ,, 40 .. ... 19. 4 „ 60 „ ... 27/- 4 3, 80 „ ... 33/-

(Carnage Paid) , , These accumulators are brand new, guaranteed and specially recommended. ^Terms Gash with Order. 8AST0NES, 228, PEHTOHViUE RD,, KING'S CROSS. IQNDON. N.j

6 volt 20 amp. ... 22/- \ 6 40 „ ... 27/6 6 „ 60 „ , ... 37/6 , 80 „ s ... 52.-' {Carriage Paid)

JUST PUBLISHED

THE "READY" M ETK00 OF EM0RISING 0RSE.

whole Alphabet can be memorised permanently in 5 MINUTES

Price 6d., or by post 6Jd. R. F. ROBERTS, 3 George St., Croydon, Wholesale: Perdval Marshall &. Co.,- 66, Farriagdon St., FX,

SflFNTIFIf APPITANfF^ Oale & HolUng). Electrical, Magnetic iumuiriL ArrLiflntr.^ 0ptical and ALx. radio wire- LESS PARTS and Materials at Lowest Prices, Call and see our immense stock or write for Information and Prices, hi Centre o/ London, Top of Kingsway,

SCIENTIFIC APPEIANCES, II and 29, Sicilian Avenue, London, W.C.I.

PORTLAND'S PARTS BY POS7 U EBONITE

8 X i 4 X 4 i7fX 5^ to X 6 7 X 5

si" d. .; /- £ s. d. 7 12 X IO ... M. 7 6 1 3 17^ X ... 9 6 6 8 x8 X 18 ... ... 12 IO 3 9 36 X 18 ... ...1 3 O 2 8 7 lb. ... ;..i 3 0

Quarter, Mat. - BRITISH Postage Free—Any Size Cut

JAMES PORTLAND, 39. SINCLAIR ROAD, OLYMPIA, W.14 7V.B. Mr. Portland Stocks 200 Wireless Parts

AT

HALL'S

PRICES THAT SPEAK

FOR THEMSELV £S

BRITISH HEADPHONES 4,000 ohms. Very ' Light, Beautifully 1 Finished. Stalioy Diaphragms. Complete with Cords. Adjust-

able Earpieces. (Sold elsewhere almost exclusively at 35/-.) 19/6 Postage 9d.

THE WELL-KNOWN French "Brunei" Headphones

22/6 POSTAGE 9ci. French " Sidep " Headphones

2 ./- POSTAGE Sd.

GUARANTEED GO>DS DESPATCHED BY RETURN

VARIABLE CONDENSERS: Capacity. Parts Assembled for

Complete. Panel Mounting. .001 7/- ... 12/6 .0075 5/9 ... 12/- .0005 ... ... 5/- ... ... 10/6 .0003 ... 3/3 ... 7/6 .0002 ... ... 2/3 .... 6/-

. .0001 ... 2/- > ... ... 4/9 Top and Bottom Circular Drilled Ebonite Plate, 1/6 extra. Vernier, 3/-, assembled. Intervalve Transformers, Ratio 4. to 1, finest

manufacture, ... 12/9; 5 to 1 14/6 Crystal Sets ... from 15/- to £3 "Royal Phone" Loud Speakers, 4,000 ohms

resistance, ebonite horn, giving clarity of tpne and freedom from distortion. each 30/-

Orders in strict rotation. Aluminium Condenser Vanes, fixed and moving, 22/24 gauge ... pair, Id- Spacers, true to .001. Small, dozl 2d.; large doz. ... ... ^ «. ... ... Sd,. Ebonite Knobs, tapped 2 B.A. with brass nut—

1st quality, 4d.; 2nd quality 2(1 Aerial Wire, 7/22 hard drawn copper, in 100 ft. lengths ... ... ... 2/5 Valve Legs, with ^auts and washers, . Id. each;

doz. ... ... i ... ... Sd. Two Coil Holders, solid ebonite mounted on mahogany ^ ... 4 4/9 Three Coil Holders, solhT ebonite, with long i .arras to avoid, capacity effects 9/6 Crystal Detectors, adjustable in every way 2/6

ditto, ditto, enclosed in glass case ... ... 4/6 Engraved Ivorine Scales, 0—180 4Id. Filament Resistances, extraordinary value,

velvet action ... • ... 2/6 and 3/6 Switch Arms, complete with knob, a collar, washers, bixsh nuts, etc. 1st quality, 1/6;

2nd quality ... ... ... ... ... ... !/• Valve Holders, turned ebonite, complete with nuts, 1/3; 2nd quality ... ... ... Sd. Crystal Cups. Plain Id.? one, t\Vo, or three screw ... ... ... 3d.

Large Terminals, complete with nut and washer Id, Basket Coils, set^ of 7 ... 5/- Contact Studs, I in. by i in., complete with nut and washer ... ... doz. 6d. Insulators, 2-in. reels- Id. each; white egg, 3d.; green egg, 4d.; green shell. ... each 4d.

Brass Nuts, 2,5,4,5,6 B.A., doz. Sd. Washers, doz. ... 2d. Ebonite Sheet, £, | ... ... ... ... Ib. 4/-

Fixed Condensers, any capacity ... ... each 1/3 Grid Leak and Condensers combined ... each 3/6 Slider Plunger, complete ^ ... each 4d. Slider Rods, 12-in. or 13-in. l-in. square brass,

drilled both ends ... ... 4d. Hertzite, 1/6- Bornite, Carborundum, Galena 4d. Screwed Brass Lengths, 12-in. 2 or 4 B.A. each 3d. Inductances, wound 22/24 enamelled wire, each 3/3 Orders under 30/- kindly remit ample post- age. Balance refunded if excess sent. Send for Free Catalogue

TRADE UfAI f >0 DISPATCH SUPPLIED JHALlL. O BY RETURN ' I" II O IV E : R B GE UNT T las2 71,71a, Beak St., Regent St., London," W.l

Between Piccadilly Circus and Oxford Circus '.Buses 3, 6, 12, 13, 15, 32, 51, 59, 61j arid 88 pass

Page 19: Amateur Wireless Magazine, Weekly, Sat 20th January 1923...Amateur Wireless Magazine, Weekly, Sat 20th January 1923. DONT MISS FREE MAP WITH CALL SIGNS NEXT WEEK Vol. 11, No. 33 SATURDAY,No

^tnaiexif ^/ireles5 JANUARY 20, (923

OUR INFORMATION BUREAU

Expert Replies to Readers' Questions. Hundreds of Replies are sent by Post. TO ENSURE A PROMPT REPLY PLEASE OBSERVE THE FOLLOWING RULES

Write distinctly, give all necessary details and keep to the point. Ask one Question at a time—never more than two. Send a Stamped and Addressed Envelope. Send the Coupon cut from page 68,

Making a Rectifier. Q.—Please tell me if I can make a vibrating

rectifier for loo volts 50 cycles from steel strip as sample enclosed.—D.H.B.McC. (Leicester) (4,606).

A—The writer cannot recommend the use of the .vibrating type of rectifier; it is an article that is gradually going out of use owing to its various unsatisfactory features. Not only is it difficult to get the vibrating tongue to oscillate in true synchronism with the frequency of the circuit, but the inter- ruptions must be timed to occur at definite intervals before and after the zero points on the voltage wave, or the accumulators will discharge as rapidly as they are charged up. The chemical rectifier or Nodon valve pos- sesses no such disqualifications and is cheap in first cost and upkeep. Directions for its

construction and a diagram of its connections are to be found in No. 29. Other means of electrification are the tungar valve and the motor generator.—A. H. A.

Direct and Loose Coupling Q.—Will you please explain the advantages

and disadvantages of direct- and loose-coupled tuners ?—S. W. S. (Cambridge).

A.—With a direct-coupled tuner signals reaching the aerial have a direct path to earth. Any signal from a near-by station, even if " out of tune " with the receiving aerial, will probably force its path through the receiver to earth and so be a cause of interference. If a loose-coupled tuner be used, however, the signals will .still force through the. circuit, and, being out of tune or resonance with the tuned aerial circuit, will be heavily damped, and

therefore incapable of causing a large inductive effect in any inductively-coupled circuit. By loosening the.coupling between primary and secondary coils the damped signals will not be induced with any great force into the secondary coil, whereas tuned signals will still be induced into this coil and good results obtained. - By employing a loose-coupled tuner, signals may be very slightly decreased in strength, but the selectivity of reception will repay any small loss. When tuning a loose-coupler, care should be, taken that the secondary has at least twice the number of turns in use as those on the pri- mary. This is to give a transformer " step- up " effect to obtain signals at the maximum strength. Tuning of the secondary should be effected by means of a small variable con- denser.—h. C.

BROADCAST TELEPHONY Some of these transmissions are commercial

or official. Wave-lengths and times are liable to alteration without notice.

London B.B.C. Station (3 L O), 369 metres. Daily, 5 p.m. to 5.30 p.m., children's stories; 6.30 p.m. to 10 p.m., concert and news.

Manchester B.B.C. Station (2 Z Y), 385 metres. Daily, 4.30 p.m. to 5 p.m., concert; 6 p.m. and 6.15 p.m., kiddies' corner; 6.30 p.m. to 7 p.m., reproducing-piano recital; 7 p.m., news bulletin; 8 p.m. to 9.10 p.m., concert; 9.15 p.m., second news bulletin; 9.30 p.m. to 10 p.m., miscellaneous concert.

Birmingham B.B.C. Station (5 I T), 420 metres. Weekdays : 6.30 p.m., children's stories ; 7 p.m., concert; 7.30 p.m., news bulle- tin; 8.30 p.m. to 9 p.m., interval; 9 p.m., concert; 9.45 p.m., second news, bulletin; 10 D.m., final announcements. Sundays; 8 p.m., news bulletin; 8.10 p.m. to 9.45 p.m., concert; 9.45 p.m., second news bulletin ; 10 p.m., final announcements. .

Newcastle B.B.C. Station (5 N O), 400 metres. Daily, usually 6.30 p.m. to 8 p.m.

Croydon (Gt E .-D), 900 metres. Daily. Writtle (2 M T). 400 , metres. Tuesdays,

8 p.m. ' Eittel Tower (F L), 2,600 metres. Daily,

5.20 p.m. to 7'p.m. and to.10 p.m. to 10.20 p.m. (weekdays only). :

The Hague il'.C G G), 1,085 metres. Sun- days, 3. p.m. to s .p.m.. .

Paris. Concerts Radiola. 1,506 metres. Daily, 5 p.m. to~ 6 p.m., concert, Sundays, 3 p.m. to 5 p.m;, concert. -

Rome (1 C D), 3,200 metres. Daily, 10 a.m. Konigswusferhausen (L P), 2,800 metres.

Daily, 4 p.m. to 5.30 p.m. Amsterdam (P C A), 1,800 metres. Daily,

i.io p.m. Haren (O P V H), 900 metres. Daily, every

hour from 11.20 a.m. to 4.20 p.m.

A film entitled "Via Radio" has been produced by the Scientific American in conjunction with the Educational Films Corporation. If explains to the layman all about broadcasting and the working of the radio compass amongst other things.

The National Association of

Radio Manufacturers AN association has recently been formed

** under the title of The National Association of Radio Manufacturers. The association has been brought into being for the avowed purpose of prevent- ing those chaotic conditions "which might arise in a new industry if the solution of all problems is left to individual effort.

It is stated that the association will not attempt to control the selling prices of the instrument's marketed by its members, but that its main objects are to establish such fair and equitable conditions of trading as are essential fo the well-being of a new industry, and to take up from time to time any question of common interest to the trade upon which united action appears to be desirable. A condition of membership is that the applicant must be a hona-fide British manufacturer of wireless appara- tus, and must be eligible for membership of the British Broadcasting Company, Limited.

We are informed that the wifeless section of the Daily Mail Ideal Home Ex- hibition, to be held ,at Olympia from March 1 to 24 (inclusive), will be under the control of this association. In- timations have recently been issued to members, and potential members, inviting applications for stands-

Messrs. Derbyshire and Co., chartered .accountants, of 4, Southampton Row, London, W.C.i, are acting as secretaries

' to the newly formed organisation, and will be pleased to furnish further particulars to any duly qualified British manufacturers who would like to consider the question of membership.

Care and Management of Primary Batteries is the title of an article which will be of interest to wireless enthusiasts in the current issue of "Work " (3d.). Other articles include; "A Self-feeding Table Fountain," "Two Accessories for the Gramophone," "Practical Upholstery," "Making a Table for Table-tennis," "Using Gas Economically," "Piano Tuning- and Repair," "Silver Work for Amateurs," "Cleats for Use in. Cleaning Joints," "American Notes Illustrated."

We have received a handsome little catalogue from Radio Instruments, Limited, 12, Hyde Street, London, W.C.i, dealing exclusively with broadcast cabinet receivers, ranging from a small 4-valve set for table use to a handsome 7-valve Chippendale cabinet set. A copy may be obtained on request.

When the captain of the American ss. Hatter as died during the voyage to New York, the burial service was wirelessed from the ss. President Adams, 250 miles away, as the Hatter as had no clergyman on board.

The transmission of pictures by wire- less has reached the stage that it is now possible to transmit and reproduce coloured drawings.

H,C, COPPER INSTRUMENT WIRES 28 80 32 88 do i'l s.w g Enamd. 2/S 3/3 3/S 3/11 4 6 6 6 8 ■ lb. S.C.C, 2/11 3/10 4/6 — _ _ _ lb. B.S.C. 3/7 S/- 6/3 7/3 9/9 16/6 20/. lb.

H.D. Aerial, 7/22. plain. 4/-; enamd., 6/- 100 ft. Terms:—C&sh. with Order. Postage extra. H0HR0CKS&ASPIN, 12,Scliwabe St., Rhodes, Manchester.

In replying to Advertisers, please make a strong point of mentioning " Amateur Wireless. "

^makuf, ^ireks5 JANUARY 20, .1923

OUR INFORMATION BUREAU ' " '■ 1 ' VV'''r. ■' . . . -

Expert Replies to Readers' Questions. Hundreds of Replies are -ent by Post. TO ENSURE A PROMPT REPLY PLEASE OBSERVE THE FOLLOWING RULES

Write distinctly, give all necessary details and keep to the point. Ask one Question at a time—never more than two. Send a Stamped and Addressed Envelope. Send the Coupon cut from page 68.

Making a Rectifier. Q—Please tell me if I can make a' vibrating

rectifier for loo volts 50 cycles from steel strip as sample enclosed.—D.ILB.McC. (Leicester) (4,606].

A—-The writer cannot recommend the use of the .vibrating type of rectifier; it is an article that is gradually going out of use owing to its various unsatisfactory features. Not only is it difficult to get the vibrating tongue to oscillate in true synchronism with the frequency, of the circuit, but the inter- ruptions must be timed to occur at definite intervals before and after th'e zero points on the voltage wave, or the' accumulators will discharge as rapidly as' they are charged up. The chemical rectifier or Nodon valve pos- sesses no,such disqualifications and is cheap in first cost and upkeep. Directions' for its

construction and a diagram of its connections ■ are to be found in No. 29. Other means of

electrification are the tungar valve and the motor generator.—A. PI. A.

Direct and Loose Coupling Q.—Will you please explain the advantages

, and disadvantages of direct- and loose-coupled tuners?—S. W. S. (Cambridge).

A.—With a direct-coupled tuner signals reaching the aerial have a direct path to earth. Any' signal "from a near-by statipn, even if " out of tune ""with the receiving aerial, will probably force its path through the receiver to earth and so-be a cause of interference. If a loose-coupled tuner be used, however the signals will still force through the. circuit, and, being out of tune or resonance with the tuned aerial circuit, will be heavily damped, and

therefore incapable of causing a large inductive effect in any inductively-coupled circuit. By loosening the ^coupling between prinjary and secondary coils the damped signals will not be induced with any great force into the secondary coil, whereas tuned signals will 'still -be induced into this coil and good, results obtamed.—Uy employing a loose-coupled tuner, signals may be. very slightly decreased in strength, but the selectivity of reception will repay any small loss. When tuning a loose-coupler, care shoiild be. taken that the secondary has at least twice the number of turns in use as those on the pri- mary. This is to give a transformer " step- up " effect to obtain signals at the maximum strength. Tuning of the secondary should be effected by means of a small variable con- denser.—I,. C.

BROADCAST TELEPHONY Some of these transmissions are commercial

or officials • Wave-lengths' and times are liable to alteration without notice.

London B.B.C. Station (2 L O), 369 metres. Daily, s .p.m. to 5.'3Q p;m., children's stories; 6.30 p.m. to 10 p.m.,-coricert'.flnd news.

Manchester B.B.C. Station (2 Z Y), 385 metres. Daily, '4.30 p.m. to 5 p.m.,- concert; 6 p.m. and 6.15 p.m., kiddies' corner; 6.30 p.m. to 7 p.m., reproducing-piano recital; 7 p.m., news bulletin; 8 p.m. to 9.10" p.m., concert; 9.15 p.m.,"second news bulletin; 9.30 p.m. to ro p.m., miscellaneous concert.

Birmingham B.B.C. Station (5 I T), 420 metres. Weekdays: 6.30 p.m., children's stories; 7 p.m., concert; 7.30 p.m., news bulle- tin; 8.30 p.m. to 9 p.m., interval; 9_ p.m., concert; 9.45 p.m., second news, bulletin; 10, u.m., final announcements. Sundays r 8 p.m., news bulletin; 8.10 p.m. to 9.4S p.m., concert; 9.45 p,m,, second news.bulletin ; 10 p.m.,' final anhounceiuents. • ;' "r1 :: • • V*- .

Newcastle B.B.C. Station (5 N O), 400 metres, . Daily',"usually Ci'.'jo p.rn'. to 8 p.m.

Croydon (tL EsD), .900 metres.- Daily. Writtle ■ (2 M T); 400., metres. Tuesdays,

8 p.m. ' Eiffel rojyer iF L),, 2,600 metres. Daily,

6.20 p.m.' toy 'p.m.^knd io.io p.m. .to 10.20 p.m. (weekdays oiily).

Thi Hague (P C ,G G), 1,085 metres. Sun- days, ,'3 .p.m.' to 5 .p.m.. .

Paris. 'Concerts Radibla.'.". 1,566 hyctfes. Daily, S,, pfm.];fd - 6'; p.m.;'concert. ^ Sundays, 2 p.m.'<.td"s?p.m;, . concert., ; ' ^ •f';,

Rome'(LC D), 3 ,200 metres. Daily, 10 a.m. Konigsw'usferhaiisen (L P), 2,800 metres.

Daily, 4 p.m. to 5.30 p.m. Amsterdam (P C A), 1,800 metres. Daily,

1.10 p.m. Haren (O P V H), 900 metres. Daily, every

hour from 11.20 a.m. to 4.20 p.m.

A film -entitled "Via Radio" has been produced by the Scientific American in conjunction with the Educational .'Films Corporation. If, explains' to the layman all about broadcasting and the working, of the radio compass amongpt other things.

The National Association of

Radio Manufacturers AN association has recently been formed

under the title of The National Association of Radio Manufacturers. The association has been brought into being for the avowed 'purpose of prevent- ing those chaotic coriditfons which might arise in a new industry if the solution of all problems is left to individual effort.

If is stated'fhat the association will not atteinpt to cb'ntrol the selling prices of the instrument's marketed by , its members, but that its main objects are to establish such fair and equitable conditions of trading as are essential fo the well-being of a new industry, and to take up from time to time any question of common interest to the trade upon which united action appears1 to be desirable. A condition of membership is that the applicant must be a bona-fde British manufacturer of wireless appara- tus, and must be eligible for membership of the ■ British Broadcasting Company, L'ipited.

W e are informed that the wireless section of the Daily Mail Ideal Hofno-Ex- hibition, to be held at Olympia from March 1 to 24 (inclusive), will be under the control of this association. In- timations have recently-, been issued to members, and potential members, inviting applications for stands.

Messrs. Derbyshire and Co., chartered accountants, of 4, Southampton Row, Lbndpn, WiC 1, are acting as secretaries to the newly formed organisation, and will be pleased to furnislt further particulars to any duly qualified .British manufacturers who would like to consider the question of membership.

Care and Management of Primary Batteries is the title of an article which will' be of interest to wireless enthusiasts in . the current issue of, "Work " (3d.). Other articles ' include A Self-feeding Table Fountain," "Two Accessories for the Gramophone," "Practical Upholstery," "Making a Table for .Table-tennis," "Using Gas Economically," "Piano Tuning and Repair," '"'Silv'er Work for Amateurs," "Cleats for Use in. Cleaning, Joints," "American Notes Illustrated."

We have received a handsome little catalogue from Radio Instruments, Limited, 12, Hyde Street, London, W.G.i, dealing exclusively with broadcast cabinet receivers, ranging from a smail 4-valve set for table use to a, handsome 7-valve Chippendale cabinet set. A copy may be obtained on request.

When the captain of the American ss. Halteras died during the voyage to New York, the burial service was wirelessed from the ss. President, Adams, ,250 miles away, as the Hatleras had no clergyman on board.

The transmission of pictures by wire- less has reached the stage that it is now possible to transmit and reproduce coloured drawings.

H.C. COPPER JNSTRUMENT WIRES Hi 28 80 52 86 40 (tas.wg Etiamd. 2/8 3/3 3/8 3/11 4/6 6/6 8/- lb. S.C.O. 2/11 3/10 4/6 — — — — lb. B.S.C. 3/7 S'- 6/3 7/3 9/9 1B/S 20/. lb.

H.D. Aerial, 7/22, plain, 4/-enamd., 6/- 100 ft. Terms.'—-Cash with Order. Postage extra. HORROCKS & ASP1N, 4fc,Sehmbe St., Rliodea, Manchester.

In replying to Advertisers, please make a strong point of mentioning " Amateur Wireless.

Page 20: Amateur Wireless Magazine, Weekly, Sat 20th January 1923...Amateur Wireless Magazine, Weekly, Sat 20th January 1923. DONT MISS FREE MAP WITH CALL SIGNS NEXT WEEK Vol. 11, No. 33 SATURDAY,No

JANUARY 20, 1923 67

I 4 BROWN STREET ONEDODR FROM MARKFT S7 MANCHESTER

G.P.O, BOX NO. 6X9. OUR

Single Valve

panel AT

Gives Remark- ably Good Results.

Full particulars, together with other sizes, will be found in our

FILAMENT RHEOSTAT. Double Head RECEIVERS. British Made. Complete with cords. 4.000 ohms, 28/"j post i -

Make Yosr Own WiffiwA H.T. BATTERIES. Terminals, which can be ywuMpr easily and securelj' attached ^4. \ to Pocket Lamp Batteries l\ * in a few minutes. 2d. each, Broadcasting post free m doz. lots. . extra

Expert knowledg

your Set twice

CONSTRUCTION OF WIRELESS APPARATUS Shows how to make every component necessary without the aid of special tools.

WIRELESS VALVES SIMPLY EXPLAINED Over 130 pages of sound explanation telling exactly how the Valve works and how to get the best results from it.

RADIO PRESS DIRECTORY 20,000 Call signs with names of Stations (commercial and amateur).

WIRELESS FOR ALL Read this before buying your Set. Tells you exactly what Radio is and the Set you'll need,

SIMPLIFIED WIRELESS A practical Book showing how to build Crystal Sets, and explaining full theory of Radio in everyday language.

1/6

2/6

2/6

6d.

H-

^jmoteur

e will make

as sensitive

KNOW hou) it works and you can easily correct any faults and tune it up to a high

state of efficiency. The requisite knowledge for this can be gained from books issued by the Radio Press. Here are some of them—all can be relied upon for dependable information. From all Bookseller; or direct from the Publishers,

Sadio freaa.ldd PUBLISHERS OF AUTHOR.ITATIVE WIRELESS LITERATURE DEVEREUX COURT, STRAND. W.C.2,

SIMPUFi®2> WIRELESS VALVu* WIR

V*:

i

VARIABLE CONDENSERS 0005 for panel mounting complete with knob, scale and • - cabinet 15/-. Rectifying Crystals. Chry- I-T I T.• F „ . f n "Rrvv /"vf pointer 8/-, in staged, the super Hertzite 6 Crystals, 1/-.

2/-. Hertzite, 1/3. Box of Post Free. WEATHERALL & CO.

ESTABLISHED 23 YEARS 28, Woodbridgc Street, LONDON, E.C.I

SOLIO EBONITE J' Sheet—18'X18", 12/-: 12"xl2", 5/6; 12"X 9", 4/-: 0" x 6", 3/:; 4" X 4", lOd, Any Size Cut. Knobs, 2 B.A., 4d, eacli; Vatve Holders and 8 Nuts, 1/- each ; Coil Holders, 1/3 each ; Rod and Tube ; i" and y Sheet; Cheap Accumulators :

Phonss: H.T. Batteries: Loud Speakers, Carkiage Paid Over 10/- BAILEY & ROBINSON 9, Esplanade, REDCAR

RADIO

COMPONENTS

All Component Parts offered by the Cheapest Firm in England.

Condensers for Panel Mounting. Capacity Assembled Unassembled

14/- 001 •0005 •0003 •0001 Vernier

10/6 6/- 51- 3/6 21-

9- 8/3 6/6 51-

Ebonite plates 2/- pair.

WRITE FOR OUR LISTS.

BOWER ELECTRIC LTD. 15, Grape Street, Shaftesbury Avenue,

'Phone : Reg. 3636. Also at 15, Kingston Road, Wimbledon, S.W.19.

'Phone : Wimbledon 1030.

BATTERIES

H.T.

Batteries

for

Valve Sets

24v. 28v. 32v.

Type B.K.

V r;

Owing to the domand [or these batteries, all orders will be dealt with in strict rotation. Prices approximately one shilling a volt.

Ask for Leaflet 4030

ELECTRICAL STORAGE COAIPANY LIMITED.

219/229, SHAFTESBURY AVENUE, W.C.2.

PRICES AND PARTICULARS ON APPLICATION.

CLIFTON JUNCTION, Nr MANCHESTER.

JANUARY 20, 1923 67

alElectricS TeZepfione.t \ Hogcrry I

O.F.O. Box No. 619 OUR

Single Valve

panel AT

Gives 1 EtemarK

ably Good Results •

FILAMENT RHEOSTAT Double Head RECEIVERS. British Made. Complete with cords. 4,000 ohms, 28/-, post x -

Make Votfr Own WaKStr H.T. BATTERIES. V| yjjgjgf/ Terminals, which can be ynBra^ easily and securely attached X. \ I/I to Pocket Lamp Batteries l\ \ III in a few minutes, 2d. each, Broadcasting Fee 6d. extra post nee m doz. lots.

Expert knowledg

your Set twice

CONSTRUCTION OF WIRELESS APPARATUS Shows how to make every component necessary without the aid of special tools.

WIRELESS VALVES SIMPLY EXPLAINED Over 130 pages of sound explanation telling exactly how the Valve works and how to get the best results from it,

RADIO PRESS DIRECTORY 20,000 Call signs with names of Stations (commercial and amateur).

WIRELESS FOR ALL Read this before buying your Set. Tells you exactly what Radio is and the Set you'll need,

SIMPLIFIED WIRELESS A practical Book showing how to build Crystal Sets, and explaining full theory of Radio in everyday language.

1/6

2/6

2/6

6d.

1/-

^mateur

e will make

as sensitive

KNOW how it works and you can easily correct any faults and tune it up to a high

state of efficiency. The requisite knowledge for this can be gained from books issued by the Radio Press. Here are some of them—all can be relied upon for dependable information. From all Booksellers or direct from the Publishers,

Hadifl ffess.lttd PUBLISHERS OF AUTHOR-ITATIVE WIRELESS HTERATURl DEVEREUX COURT, STRAND. W.C.2;

SIM* WIRE , -nr 1. J .•

/AcncAi vtstim AlVC CIRCUITS W4

9-*

VARIABLE CONDENSERS ooos for panel mounting complete with knob, scale and pointer 8/-, in cabinet 15/-, K.ectifying_ Crystals. Chry-

SOLID EBONITE

.tagod, the super Hertzite, 6 Crystals, 1/-. a

Hertzite, 1/3. Box of Post Free. CO. WEATHERALL &

ESTABLISHED 23 YEARS 28, Woodbridge Street, LONDON, E.C.I

i" Sheet—18"X18", 12/-; 12"xl2'/, 5/6: 12" X 9", 4/-; 9" x 6", 3/:; 4" x 4", ibd. Any Size Cot. Knobs. 2 B.A., 4d, each; Valve Holders and

8 Nuts, I/- each ; Coil Holders, 1/3 each ; Red and Tube ; t" and Sheet; Cheap Accumulators : Phonss; H.T. Batteries; Loud Speakers, Carriage1 Paid Over 10/- BAILEY & ROBINSON 9, Esplanade, REDCAR

RADIO

COMPONENTS

All Component Parts] offered by the Cheapest , Firm in England.

Condensers for Panel Mounting. Capacity Assembled Unassembled

14/- 10/6 001 •0005 •0003 •0001 Vernier

6/- 5/- 3/6 2/-

9- 8 3 6/6 5/-

Ebonite plates 2/- pair.

Write for our lists.

BOWER ELECTRIC LTD. 15, Grape Street, Shaftesbury Avenue,

'Phone: Regr. 3636. Also at 15, Kingston Road, Wimbledon, S.W.19.

'Phone! Wimbledon 1030.

Exifec

BA7 TERIES

H.T.

Batteries

for

Valve Sets

24v. 28v 32v.

Type B.K.

f

Owing to the demand (or these batteries, all orders will be dealt with in strict rotation. Prices approximately one shilling a volt.

Ask for Leaflet 4030

<01 ELECTRKAL STORAGE COMPANY LIMITED.

CLIFTON JUNCTION, ] 219/22^ SHAFTESBURY Nr MANCHESTER. | AVENUE, W.C.2.

PRICES AND PARTICULARS ON APPLICATION.

Page 21: Amateur Wireless Magazine, Weekly, Sat 20th January 1923...Amateur Wireless Magazine, Weekly, Sat 20th January 1923. DONT MISS FREE MAP WITH CALL SIGNS NEXT WEEK Vol. 11, No. 33 SATURDAY,No

I

fltnatmr

CLUB DOINGS

Leeds and District Amateur Wireless Society. Hon. Sec.—D. E. Pkttigrew, .37, ' Mcxborough Avenue, Chapeltown Road, Leeds. Ox Jan. 5 the chairman called upon Mr. T. Brown, Thomson to lecture upon the " Transmission of Photographs by Wireless." The lecturer sketched the methods that have been used since 1847, paying particular attention to the efforts of Knudsen in 1908. Mr. Thomson expressed his belief that it would soon prove to be possible to transmit an ordi- nary negative without the use of special plates, and advocated the use of undamped waves for , such a transmission. Various method^ of transmission, using spark, arc or valve," were briefly considered, and arrangements,of receiving apparatus examined. The great problem of synchronisation between the transmitter and receiver was closely considered.

Wandsworth Wireless Society. Hon. Set.—F. V. Copperwheat, 9, Birdhurst Rd,, Wandsworth, S.W.18. By the courtesy of Captain E. S. Davis members of the above society were accorded an interesting evening on Wednesday, Dec. 20, at "The Pavilion," Marble Arch, better known probably as 2 B Z. On arrival the party were ushered into the private theatre and several films of an educational charac- ter were shown, these being interspersed with broad- cast music. During the changing of one of the films the opportunity-was taken of recording wireless telephony and music on- a dictaphone, ancT the re- production was amazing for its clarity. The an- nouncement that loud-speakers could be made out of tooth-powder tins' caused no small comment, but upon producing the instrument so named and sub- jecting it to isevere working conditions those present had to admit that this was possible where ZKL was concerned. After partaking of some re- freshment kindly provided by the host, the party

.proceeded to the power house. This was a very "extensive one .with1 several generators, main dis- tribution panels, air compressors and battery rooms.

Battersea and District Radio Society. Hon. Sec.—F. J. Lisney, 66, Ncwland Terrace, Queen's Road, S.W.8. # # Ai.l amateurs in the district are invited to join the above society. Particulars can be obtained from the secretary.

58 Tottenham Wireless Society

If on. Sec.—R. A. Barker, 22, Broadwater Road, Bruce Grove, Tottenham, N'.17. Ox Jan. 3 Mr. H. Winter gave a ve'ry excellent vlecture, his subjecf" being "Telephone Receivers." ■ All persons interested in the above society should apply immediately to the secretary for particulars.,

Bournemouth Radio and Electrical Society. Hon. Sec.—h. O. Sparks, s" Maranoa," 3, Cotlands Road, Bournemouth'. The above society has now been formed, and all those interested in . wireless or any electrical mat-

. ters are invited to communicate with the secretary, who will be pleased to supply them with any,in- formation required.

Croydon Wireless and Physical Society. Hoji. Sec.—B. Clapp, Mcadmoor, Brighton Road, Parley. A meeting of the Croydon Wireless and Physical Society was'held On Jan. 6, at which Lieut. D. Sin- clair delivered a lecture entitled "The Signals Organisation of Our Airways." Lieut. Sinclair ex- plained very fully the methods by which the machines on-the ,air routes are controlled and their positions determined by wireless telephony. He said that the wavelength of 900 metres was now used exclusively for communication with aircraft. Any messages required to be sent from one aerodrome to another are transmitted either by wireless tele- graphy via the Air Ministry (G.F.A.) on a wave- length of 1,400 metres or by private, landline, whilst weather reports are sent by the Air Ministry on a 1,680 wavelength. Some very excellent lantern slides were shown illustrating the aerials and apparatus at the W/T stations* at several of the aerodromes in England.

Ipswich and District Wireless Club. Hon. Sec.—H. E. Barbrook, 46, Foundation Street, Ipswich. On Jan. 8 a very successful and interesting evening was spent, when a good number enjoyed what will be known as the first demonstration of broadcasting grand opera by wireless. The club set was used on this occasion, with the addition of a two-valve note magnifier, a microphone amplifier and loud- ispeakcr, thus enabling all present to " listen-in " without the trouble of headphones. Mr. Bird was the operator for the evening, and having tuned in 2 L O was picked up, the reception being very clear. The opera transmitted was the " Magic Flute," and the tuning of the orchestra was clearly heard, as was also" the tapping of the conductor's baton. The music and singing came through with very little distortion, although the words of the singers were rather difficult to follow.

JANUARY 20 " 1923

Stoke-on-Trent Wireless and Experimenta'i Society. Hon. Sec.—F. T. Jones, 560, Cobridge Road, Haxilcy. A meeting, of the ,above society was held on Jan. 4, a lecture, -being delivered by Mr. R. W. Steel on " Sources of Electrical " Current." In the opening portion of his address he explained the nature, of electricity Ey means of the electron theory. ; He then went' on to describe the various methods of producing electricity, classifying_ them under four main . headings—electrical, chemical, thermal and dynamical. , .

Thames Valley Radio and Physical Association. Hon. Sec.—E. A. Rogers, 17, Leinster Avenue, East Sheen, S.W.I4. On Jan. 4 Mr.. Jocclyn lectured on "Induction." With a series of experiments and, liberal blackboard sketches .the lecturer proved both interesting and instructive.

ANNOUNCEMENTS •• Amateur Wireless and Electrics.*1 Edited by

Pcrnard E. Jones. Price Threepence. Published on Thursdays and bearing the date of Saturday imme- diately following. It will be sent post free to any part of the world—3 months, 4s. 6d.; 6 months, ts. gd , 12 months, 17s. 6d. Postal Orders, Post Office Orders, or Cheques should be made payable 10 the Proprietors, Cassell & Co. Ltd.

General Cdrrespondence is to be brief and written on one side of the paper only. All sketches and drawings to be on separate sheets.

Contributions are always welcome^ will be promptly considered, and if used will be paid for.

Communications should be addressed, according to their nature, to The Editor, The Advertisement ,Manager or The Publisher, "Amateur Wireless/* La Belle Sauvage, London, E.C.4'

otote*^

£Ind Electrics

Querist's CouponAvailable until Saturday, Jan. 27, 1923

IMPORTANT

WE HAVE OPENED VERY COMMODIOUS PREMISES AT

54, Gracechurch Street, E.C.3

for the demonstration and sale of all types of Wireless Receiving Sets and "Claritone" Loud Speakers.

Amateurs and Experimenters will for any type of Set including ;

Transformers, L.F. and H.F. Headphones, all types, all resistances Condensers, variable and fixed, all capacities Varlo-couplers and Variometers Coil-holders and Coils Anti-capacity Switches, all types Rheostats, all types Radial Switches, 3-, 10- and 15-way Ebonite Valve Holders, Dials, Scales, other

parts and in sheet PRICE LIST FREE

be able to obtain every part required

Valves, M.O. and Mullard's Brass W.O. and Telephone type Terminals,

Nuts, Washers, Contact Studs and all other parts Accumulators Dry Batteries Aerial Wire Insulators Hertzile and Galena Crystals Cotton and other Tubings, all colours

Etc. etc. ON APPLICATION

PETTIOREW & MERRIMAN, Ltd., 122=124, Tooley Street, London, S.E.f Note: Gracechurch Street is a few minutes from Monument, Eastcheap, Bank, Cannon Street & London Bridge

TELE.: HOP 134

^inateur ^/ireles5

CLUB DOINGS

Leeds and District Amateur Wireiess Society. Hon. Sec.—D. E. Pettigkew, ' ,37,; ' Mexborough Avenue, Chapeltown • Road, Leed?. . - - ' On. JaU, 5 the chairman called'upon Mr,. T. Brown^ Thomson' to lecture upon . the ■** Transmission of Photographs' by Wireless." The lecturer sketched the-metliods that have been used since 1847, paying particular attention to the efforts of Knudsen m 1908- Mr. Thomson expressed his belief that it would soon prove to be possible! to transmit an ordi- nary negative, without, the u^e of special plates, and advocated the use of undamped waves for , such a transmission. Various . method^ of transmission, using spark,' arc or' valvewere briefly considered,' and arrangements .of rcccjviflg ^apparatus; examined. The great, problem of synchronisation between the transmitter and receiver was closely considered.

Wandsworth Wireless Society. Hon. SeC.—l?. V. Copperwheat, 9, Birdhurst Rd,, Wands worth, S.W.18. By the courtesy of Captain E. S, Davis members of the above so&iety were accorded an interesting evening on Wednesday, Dec.. 20, at " The Pavilion," Marble Arch, better known probably, as 2-BZ. _ On arrival the party were ushered into the private theatre and several films of .an educational charac- ter were shown,,these being interspersed with broad- cast music. During the changing of one of the films, the opportunity-was taken of recording wireless telephony and •music on. a dictaphone, and" the . re- production >w.a£ amazing for its clarity. The an- nouncement that loud-speakers could be made out of tooth-powdCr tins'" caused no small comment, but upon producing" the instrument so named and sub- jecting it to .Isevere, , working conditions those present had to admit that this was possible where ZKL was concerned. After partaking of some re- freshment kindly provided by the host, the party

.proceeded to the power house. This was a' very \ extensive " one with v several generators, main dis- tribution panels, air compres.sors and battery rooms.

Battersea and District Radio Society, Hon. Sec.—V. J. Lisney, 66, Newland. Terrace,.: Queen's Rbad, S.W,:8- , ...... All amateurs in the district are invited to join the/ above society. Particulars can be obtained from the secretary.

68 Tottenham Wireless Society

Hon. .SVC.—R. A. .Barker,' 22, Broadwater Road, Bruce-Grove, Tottenham, N.'.17. -

Jan. 3 Mr. H. Winter gave a- ve?ry excellent ■vlecture,- his subjeqTbeing ^'Telephone Receivers.." All persons .interested in 'the above society should

apply immediately to the secretary for particulars.j j- Bournemouth Radio and Electrical Society.

Hotp. Sec.—-Is. O. Sparks, x" Maranoa," 3, ■Cotlands. Road, Bournemouth* The above society has now been formed, and all those-interested in wireless or any electrical mat-'

. ters are invited to communicate, with the secretary;- who ...will be pleased to supply thera with . any ,vin- fonnation required. ... ,

Croydon Wireless and Physical Society. Hon. Sec.—B. Clapp, Meaclmoor, Brighton Road, Purley. " ■ s ' A meeting of the Croydon Wireless and Physical So'ciefy was "held on J a n. 6, a t wh i ch Li e u t. D; Si n - clair> delivered' a lecture entitieel "The Signals. Organisation of Our ^Airways." Lieut. Sinclair, ex- plained very fully.. the methods by which : the" in a chines on - the -air routes are controlled and their positions determined by wireless telephony, lie. said that the. wavelength of 900 metres was now used exclusively , for communication . with aircraft. Any messages./required to be sent •from one aerodrome to another are transmitted either by wireless tele- graphy via the Air Ministry (G.F.A.) on a wave- length of 1,400 metres or by private,landline, whilst weather reports are sent by the Air Ministry on a 1,680 wavelength; Some very excellent lantern slides were shown illustrating the aerials and apparatus at the W/T stations* at several of the aerodromes in England.

Ipswich and District Wireless Club. Hon. Sec.-—H. E. Barbrook, 46, Foundation Street, Ipswich. On. Jan. 8 a very. successful and interesting evening was spent, wlifeu a good number enjoyed what will be know it- as the first demonstration of broadcasting grand opera' by wireless. The club set was used on this occasion, with the addition .of a two-valve note magnifier, a microphone amplifier and loud- ispeaker, thus enabling all present to "listen-in" without the trouble of headphones. Mr^ Bird was the "operator for the evening, and having tuned in 2 L O was picked up, the reception. being very clear. The opera transmitted was the " Magic Flute," and the tuning 'of the orchestra was clearly heard, as was als.o" the tapping of the conductor's baton. The music and singing came through with very little distortion, although the words of the singers were rather difficult to follow. - " -

JANUARY 2r 1923

Stoke-on-Trent Wireless and Experimenta'i Society. Hon. Sec.—IS. T. Jones, 360, Cobridge Road, Haiflifey/ A meeting of the ,above society was held on Jan, 4, a decture, -being delivered .by Mr. R. W Steep on

'' " Sources of Electrical" Current.^ In the opening portion of bis address he • explained the nature; of electricity sjby, nicans ', of , the -electron theory. ' He

.then went' on to "describe 'the 'various methods of producing electricity, classifying . them under four main headings—electrical, chemical, , thermal •and

' dynamical. - " " .. • ' h: > - 'f-. Thames .Valley Radio and Physical Association.

Hon. Sec.—E.- A. Rogers,' 17, Leinstcr AVcnue, Khst Sheen, .S.W. 14.-. . , On Jan. 4 Mr,,. Jocelyn Idcturcd on " Induction." With >series;..of experiments' aiid'riiberal■ bla-ekbodrd sketches.^the lecturer proved • both interesting . and instructive. ' V -'\ : - j . ' . _

ANNOUNCEMENTS ••Amateur Wireless and Electrics." Edited by

Pcrnard E. Jones. Price Threepence. Published on Thursdays and bearing the date of Saturday imme- diately following. It will be sent post free to any Tart of the world—3 months, 45. 6d. ; 6 months, fcs. gd ; 12 months, 17s. 6d. Postal Orders, Post Office Orders, or Cheques should be made payable to the Proprietors, Cassell & Co. Ltd.

General Cdrrespondence is to be brief and written cn one side of the paper only. All sketches and drawings to be on separate sheets.

Contributions are always welcome^ will be promptly considered, and if used will be paid for.

Communications should be addressed, according to their nature, to The Editor, The Advertisement „Manager or The Publisher, "Amateur Wireless/*

'La Belie Sauvage, London, B.C.*.

otid Electrics

Querist's Coupon Avui I able until Saturday, Jan. 27, 1923

IMPORT ANT

WE HAVE OPENED VERY COMMODIOUS PREMISES AT

54, Gracechurch Street, E C .3

for the demonstration and sale of all types of Wireless Receiving Sets and " Claritone" Loud Speakers.

Amateurs and Experimenters will be able to obtain every part required for any type of Set including;

Transformers, L.F. and H.F, Headphones, all types, all resistances Condensers, variable and fixed, all capacities Vario-couplers and Variometers Coil-holders and Colls Anti-capacily Switches, all types Rheostats, all types Radial Switches, 5-, 10- and 15-way Ebonite Valve Holders, Dials, Scales, other

parts and in sheet

Valves, M.O. and Mallard's Brass W.O. and Telephone type Terminals,

Nuts, Washers, Contact Studs and all other parts Accumulators Dry Batteries Aerial Wire Insulators Hertzite and Galena Crystals Cotton and other Tubings, all colours

Etc.' etc. PRICE LIST FREE ON APPLICATION

PETT1GREW & MERRIMAN, Ltd., 122=124, Tooley Street, London, S.E.I Note: Cracechurch Street is a few minutes from Monument, Eastcheap, Bank, Cannon Streets London Bridge

TELE.; HOP 134

Page 22: Amateur Wireless Magazine, Weekly, Sat 20th January 1923...Amateur Wireless Magazine, Weekly, Sat 20th January 1923. DONT MISS FREE MAP WITH CALL SIGNS NEXT WEEK Vol. 11, No. 33 SATURDAY,No

JANUARY 20, 1923

BROADCASTING RECBPT10N SETS

One-Valve Set Complete for Working, £7 10s.

Passed for Broadcasting Licence G.P.O.

No. 1038.

SEND FOR CATALOGUE

Agents Wanted.

DESCRIPTION : Single Valve, mounted on polished J-in. Ebonite Panel with Variable

Condenser, smooth acting resistance, grid leak and condenser and all terminals clearly engraved in white, in a Mahogany Polished Cabinet 9 in. by 5 in. by 5 in. £3 15 0 A TAPPED COIL for wave-lengths up to 900 metres with 2 ter- minals for coils for any higher wave - lengths.

The coil is enclosed and the tappings are brought out to an 8-way switch mounted in the front of the cabinet.

i s

ACCESSORIES INCLUDED: Siemens' 54-volt high-tension Battery with plugs

for altering the voltage 4-volt so-amp.-hour low-tension Accumulator in

case with carrying strap One pair of Sensitive Headphones of 4,000 ohms

resistance One Detecting Valve

15 0

14 0

1 1 15

Total £7 10 O Plus B.B.C. Royalties.

WIRELESS INSTALLATIONS Ltd. IS, Aldersgate St., London, E.G.

We are now in the

position to supply

ED1SWAN A.R. 6 volt VALVES

from Stock at

FULL MAKERS' DISCOUNT

WIRELESS INSTALLATIONS Ltd. 15, Aldersgate St., London, E.G.

| DO YOU READ PRACTICAL BOOKS? |

EE See Cassell's List of Technical, Practical and Money-saving EE EE Books. A p.c. will ensure your receiving it. =

i CASSELL & Co., La Belle Sauvage, LONDON, E.C.4. | siliiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiniiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiliiiiiiiiiiil

METROPOLE GARAGE, Showrooms, Opposite HOTEL METROPOLE, BLACKPOOL.

FOR ALL RADIO REQUISITES Ask for Our List. We Can Save You Pounds. The Finest Stock of Qualify Wireless Accessories in the North. Astounding Prices & Real Service.

SHEET EBONITE, i in. & A in. ... 3/9 per lb.! !

69 ^moUur l^uxless

WAXES' CRYSTAL RECEIVING

SET Costs but £5—Receives

Broadcasting within 30 miles,

CUPPLIES up to three head- ^ phones with music or speech from a Broadcasting station 30 miles away.

The movement of one switch arm will enable to receive Tele- phony or Telegraphy with re- markable clarity.

Dimensions 9 in. by 9 in. and 82 in.high. Complete in highly polished mahogany case, with Sterling Headphones, 100 ft. 7/22 Aerial, 2 Econ Aerol Insu- lators, I Aluminium Pulley.

Price £5-0-0

including all Royalties and Taxes. NO EXTRAS.

First cost is all—no batteries to need recharging.

Send at once for list or call for demonstration.

We supply complete Receiving Sets (Crystal or Valve) also all component parts, of which the following is an abbreviated list: "Ideal" Va've Accumu- lat.r, 4 volt 50 amp. 24/- per set (Carriage, 2/- ) "IdealV Valve Accumu- lator, 6 volt 50 amp. 35/- per set (Carriage. 3/-.) Filament Resistances Variable Condensers (of various capacities.) from Fixed Condensers, from Pyramid H.T. Battery, 15 volt .. Pyramid H.T, Batterv, 30 volt wit 1 variable ping connection Three-coil Holder, com- plete unit

5/- each 6/- each 2,6 each 3/6 each 7/- each

20/- each

Wates Bros. 13/14, Great Queen Street, KINGSWAY, LONDON, W.C.2.

iThe "BROWN"!

LOUD SPEAKERS

H, 2 (small size).

Height 12 in.

Illustrated Catalogue of Head- phones, Loud Speakers and

Amplifiers, post free.

with new improved Curved Horns

rpHE requisites of a Loud Speaker are pure tone, clear articulation,

and good volume of sound. The. BROWN Loud Speaker possesses all! these qualities in a marked degree.) Type H. 2 has been designed to meet home requirements, both as to volume

of sound and price. PRICES

H. 2 (Small), Low Resistance. 120 ohms, height 12 in. £3 O O

H. 1 (Large), Low Resistance. 120 ohms, height 21 in. £6 5 0

(High Resistances for either size,2/6 to 5/- extra.) THE BROWN MICROPHONE

AMPLIFIER. !

This amplifier gives a magnification much greater' than that obtained from a two-valve amplifier, | Prices

Low Resistance (120 ohms input), £6 0 0! High Resistance (2,000 ohms input), £6 2 5; Our apparatus can "be obtained from all

wireless dealers* Sole Manufacturers :

S. G. BROWN, LTD, London Showrooms:

19, MORTIMER STREET, LONDON, W.l Head Office and Works; Victoria Road, North Acton, W.3

JANUARY-20, 1923

BROADCASTING RECBPTION SETS

One-Valve Set Complete for Working, £7 10s.

Passed for Broadcasting Licence G.P.O.

No. 1038.

SEND FDR | CATALOGUE I

DESCRIPTION: Single Valve, mounted on polished J-in. Ebonite Panel with Variable

Condenser, smooth |isi> ' acting resistance, grid SKuSit, leak and condenser and

all terminals clearly engraved in white, in a Mahogany Polished Cabinet 9 in. by 5 in. by 5 in. £3 ,15 0 A TAPPED COIL for wave-lengths up to 900 metres with 2 ter- minals for coils for any higher wave - lengths.

The coil is enclosed and_ the tappings are brought out to an 8-way switch mounted in the front of the cabinet.

m Agents Wanted.

ACCESSORIES INCLUDED: Siemens' 54-volt high-tension Battery with plugs

for altering the voltage 4-volt jo-amp.-hour low-tension Accumulator in

case with carrying strap One pair of Sensitive Headphones of 4,000 ohms

resistance One Detecting Valve

15 0

1 $ 0

1 1 15

Total £7 10 0 Plus B.B.C. Royalties.

WIRELESS INSTALLATIONS Ltd. IfJ, Aldersgate St., London, E.C.

We are now in the

position to supply

EDlSWAN A.R. 6 volt VALVES

from Stock at

FULL MAKERS' DISCOUNT

WIRELESS INSTALLATIONS Ltd. 15, Aldersgate St., London, E.C.

69 ^moUur ^ircks^j

WAXES' CRYSTAL RECEIVING

SET Costs but £5—Receives

Broadcasting within 30 miles.

SUPPLIES up to three head- phones with music or speech

from a Broadcasting station 30 miles away.

The movement of one switch arm will enable to receive Tele- phony or Telegraphy with re- markable clarity.

Dimensions 9 in. bj 9 in. and 8| in.higb. Complete in highly polished mahogany case, with Sterling Headphones, 100 ft. 7/22 Aerial, 2 Econ Aerol Insu- lators, 1 Aluminium Pulley.

Price £5-0-0

including all Royalties and Taxes. NO EXTRAS. i

First cost is all—no batteries to need recharging.

Send at once for list or call for demonstration.

DO YOU READ PRACTICAL BOOKS?

EE See Cassell's List of Technical, Practical and Money-saving == Books. A p.c. will ensure your receiving it. =

1 CASSELL & Co., la Belle Sauvage, LONDON, E.C.4. 1

METROPOLE GARAGE, Showrooms, Opposite HOTEL METROPOLE. BLACKPOOL.

FOR ALL RADIO REQUISITES Ask for Our List. We Can Save You Pounds. The Finest Stock of Quality Wireless Accessories in the North. Astounding Prices & Real Service.

SHEET EBONITE, 1 in. & A in. ... 3/9 per lb.! !

We supply complete Receiving | ; Sets (Crystal or Valve) also all ;

component parts, of which the ; following is an abbreviated list: • "Ideal" Va've Accumu- • lat.r, 4 volt 50 amp. 24/- per set : . (Carriage, 2/-) • " IdealV Valve Accumu- : lator, 6 volt 50 amp. 35/- per set j (Carriage. 3/-.) Filament Resistances Variable Condensers (of various capacities) from .. Fixed Condensers, from Pyramid H.T. Battery, 15 volt .. Pyramid H.T. Batterv, 30 volt wit 1 variable plhg connection Three-coil Holder, com- plete unit .. ..

5/- each 6/- each 2.6 each 3/6 each , 7/- each

20/- each

Wales Bros. 13/14, Great Queen Street, H1NGSWAY; LONDON, W.C.2.

iThe "BROWN"!

LOUD SPEAKERS

with new improved Curved Horns

rpHE requisites of a Loud Speaker are pure tone, clear articulation,i

and- good volume of sound. Thei BROWN Loud Speaker possesses. all; these qualities in a marked degree/ Type H. 2 has been designed to nieet; home requirements, both as to volume

of sound and price. PRICES

H. 2 (Small), Low Resistance., 120 ohms, height 12 in. £3 0 0.

H. X (Large), Low Resistance. 120 ohms, height 21 in. £6 5 O

(High Resistances for either size,2/6 to 5/- extra.) THE BROWN MICROPHONE

AMPLIFIER. ' This amplifier gives a magnification much greater1

than that obtained from a two-valve amplifier.^ Prices

Low Resistance (120 ohms input), £6 0 01 High Resistance (2,000 ohms input), £6 2 5|

Our apparatus can he ohiained from all wireless dealers* y Sole Afanu/acfurers :

S. G. BROWN, LTD, London S/iouirooms r

19, MORTIMER STREET, LONDON, W.l Head Office and Works: Victoria Road, North Acton, W.3

H. 2 (small size).

Height 12 in.

Illustrated Catalogue of Head- phones, Loud Speakers and

Amplifiers, post free.

Page 23: Amateur Wireless Magazine, Weekly, Sat 20th January 1923...Amateur Wireless Magazine, Weekly, Sat 20th January 1923. DONT MISS FREE MAP WITH CALL SIGNS NEXT WEEK Vol. 11, No. 33 SATURDAY,No

^Irruxkur ^ireles5 70

X, O. BUSS

SCIENTIFIC INSTRUMENT

MAKER

77, CLERKENWELL ROAD, LONDON, E.C.I. ESTABLISHED 1850. E^'bibltiOU Hwai'pg—London, 1862. Sydney. 1879. Melbourne. 1880.

HEADPHONES Genuine French Telephones, most sensitive obtainable, 6 Tungsten poles in each earpiece. 4,000 ohms with cords (Double Receivers) ... post free

19'6

CONDENSERS. Complete Sets of Parts.

Assembled Complete for Cabinet Mounting,

Approx. Capacity Microf'ds. No. of Plates. Price.

Approx. Capacity Microfds.

Price,

•001 •0007s •0005 •0003 •0002 •000 i

57 43 SO 19 13 7

7/6 6/9 5/6 A6 3/6 3/-

•001 •0003 •0003 •00003

16/. 12/6 11/6 6/6

Postage 11- per set extra.

WIRELESS PARTS AND ACCESSORIES

"EBONITE"

thick Postage Free, A ny Size cut.

:: Malt surface

French " Brunei " Headphones 4,000 ohms 22/6 POSTAGE 9d.

s. d. £ s. d. 8 X 1 7 12 x 10 ... 7 6 4 X 4 1 3 mx 85 ... ... 9 6 7 X 53 ... 2 8 18 x 18 ... ... 12 10

10 X 6 ... 3 9 36 x 18 ... ... 1 3 0 17 X 5 ... 5 3 7 lb. ... 1 30

Variable Condensers Instrument Wires

British Made Copper Wires. Per lb.

yds. ohms S.W.G. per lb. per x.ooo S.C.C. D.C.C. S.S.C. D.S.C. Enmld.

yds. 22 140 39 2/9 3/- 4/- 5/- 2/7 24 230 63 3/- 3/6 4/6 6/- 2/8 26 340 95 3/7 4/1 5/- SI- 3/2 28 530 140 4/4 4/8 6/- 9/- 3/6 30 716 200 5/- 5/8 7/- 10/- 3/10 32 950 262 6/- 7/3 8/- 12/6 till 34 1,300 362 71- 8/3 9/- 13/6 4/4 36 2,000 550 8/8 10/- 12/- 15/6 4/8

Wireless Crystals

5/-

2d. 4d.

each 5d. each 45^. each 4d. each 3^d.

each 3d. By post,

Aerial Wire, 7/22 bare copper, stranded. Price per 100 ft., 3/-. By post, 4/6. Aluminium Vanes, 2 doz., 1/-. By post, 1,6. gross; by post, 6/-. t Basket Coils, 7 in set, 5/- set. By post, 5/6.

Brass Washers, 2, 3, 4 or 5 B.A dozen „ Nuts, 2, 3, 4 or 5 B.A. dozen Brass Rod (screwed)—

2 B.A., in 12-in. lengths ... 3 B.A., in 12-5n. lengths ... 4 B.A., in 12-in. lengths ... 5 B.A., in 12-in. lengths ...

Copper Foil Sheets, uniform thickness, 12 in. bv 3 in ••• Crystal Detectors on Ebonite. Each 2/6. 3/-. Also 3/3; by post, 3/9. . , 1 ,

Crystal Detector, cup enclosed with glass cover, dust proof, 4/6. By post, 5/3. , Ebonite Dials, with engraved scale 0180, 1/- each.

By post, 1/6. Egg Insulators, 4 for lid.; 2/6 per doz. By post, 3/6 doz. Filament Resistances. Each 2/6 and 3/6. By post,

3/- and 4/-. Filament Resistance Suitable for one, two or three valve sets 4/-. By post, 4/6-

Fixed Condensers, with terminals on ebonite, .0003, .0005, .001. .002, .003, 1/6; by post, 1/9; 004, 1/9; by post, 2/-.

Grid Leak and Condenser, .0003, high quality, 3/9. By post, 4/3. Inductance Coils Wound Enamel Wire, 12 by 4, 3/-. By post, 5/-. Insulating Sleeving, 6 yds. for 2/2. By post, 2/6. 12 yds. for 4/-. By post, 4/6. Intervalve Transformers (low frequency), tested and guaranteed 5-1, 14/- each. By post, 15/-. ,

Knobs, with brass nut (2 B.A.), 4^1. each. By post, 7d., 6 for 2/- By post, 2/6. Large Spacer Washers, 3 doz., 9d. By post, 1/-. Lead-in Tubes, ebonite with brass terminals, 9 in., 1/2. By post, 1/6. 12 in., 1/4. By post, 1/8. Reel Insulators, Id. each. By post, 2/- doz. Slider and Plunger, 5d. By post, 7d.

Slider Knob, Plunger and 13 in. rod, 8d. the set. Cannot be sent by post. Small Spacer Washers, 6 doz. 1/-. By post, 1/4. Switch Arms, with polished knob, bushed 2 B.A. nui:,

laminated blade, spring coil washer, nuts and bush, 1/-, 1/6, 2/- each. By post, 1/3, 1/9, 2/-. Terminals, telephone, with nut and washer, 2/- doz.

. By post, 2/6. Terminals (large), aerial and earth, complete with

2 nuts arid 2 washers (2'B.A.), 2 for 8d. By Jpst; 1/^ ■ ' Tin Foil, free from • lead, Sheets 26 in. by 13 in. ... each 4d. War Office Pattern Terminals, with nut and washer, 2/- doz. By post, 2/6.

" Hertzite " Is. Gd Z incite Gd Silicon Gd Bornite Gd Copper Pyrites Gd Wood's Metal 2s.

• Post free -

Carborundum 6d Molybdenite 6ci Iron Pyrites 6d Galena 6d Graphite 6d

Dram Tellurium 2s 6d

Intervalve Transformers

15/- Ratio 5 to 1

Post Free,

Celluloid Accumulators We are introducing a new model consisting of Jindividual two volt units. This MODEL to be known as T.g has an actual capacity of 18 ampere hours, and an intermittent capacity of 34 ampere hours.

PRICE AS FOLLOWS 2 volt 6/- each 4-volt ... ... 11/9,, 6 volt 17/6 „

H.T. Batteries, 30 volt, 6/- (by post, 7/6). H.T. Batteries, Co volt, 12/- (by post, 13/6).

Inductance Tubes Cardboard

12 in. by 4 in., 8d each. Posted.

Mahogany Boxes Polished 4i x 4i x 32 in. 4i x 4i x 5 in. Of x 0/ x 4 in. 13x64x4 in.

3/- 3/6

Post 3d 6d

4/8 1/- 8/- x/-

JANUARY 20. 1923

Notice to Advertisers

ADVERTISEMENT* INSTRUCTIONS and copy for " Amateur Wireless" should be at the office by First Post on FRIDAY morn- ing at the latest.

PREPAID ADVERTISEMENTS. B.A. Screws, Nuts, and Washers, assorted gross,

as.; list, 2d.—J. H. Bennett, Station Road, Willesden Junction. i^r

Working Drawings for wiring sketches supplied.— Puckle, Buckhurst Hill, Essex. Telephone, Wood- ford 400. . i4s

Wireless Goods Cheap—Ex-Army transmitters, 15s. ; 1 in. spark coils, 8s. ; 80-metre sets, transmit- ting, 10s. ; mine exploder dynamos, 17s. 6d.—Below. New Goods.—Low-frequency intervalve trans- formers, 16s. ; filament resistance, 23, 6d. ; valve- holders, Is. ; crystal detectors, 2s. 6d. ; switch arms, is. 9d. ; contact studs, 9d. doz. ; terminals, Id. and 2d. each; block condensers, Is. 6d. each; variable condensers, .0003, 7s. 6d; .0005. 9s.; 001, 12s. ; vernier, .00005, 5s. ; condenser vanes, Is. doz. pairs. Please call and inspect showrooms. Three days' approval against cash.—E. J. Galpin, 16, Loampit Hill, Lewisham, S.E.13, London. [2 s Potentiometers—Invaluable for grid control and crystals, adapt an ex-naval rheostat, 260 ohms, 16 stud. Price, Is. 6d., post free; excellent value.— Monk, 4, Alma Road, Plymouth. [3 s "Work" Short Wave Receiver, ,^2. Two-slide coil. Perikon, 9s. Or exchange valve accessories.— 14, Scoutbottom, Mythoimroyd. [1 s Telephone Receivers Rewound up to 1,000 ohms, 5s. ; 2,000 ohms, 7s. 6d. ; cash with order.—M. E. Hampshire, 139, Sydenham Road, S.E.26. [6r

Trafford No. 2 Crystal Set, without phones, £2. —Kerr, 62, Farleigh Road, Stoke Newington. [5 s

EASY TERMS OR CASH Startling Advertisement Offer, for fourteen days on'y- Complete Single Valve Set of parts for 90/-, 33/- with order, balance XI/- a .fortnight. Specification:—Ebonite Panel xo • 8 drilled, Milliard Ora Valve, Variable Condenser *0003, Filament Resistance, Grid Leak and Con- denser, Two Honeycomb Colls No. 35 and 50 and Holders, Variable •IT. T. Battery 30 volt, Accumulator 4 volt 30 amps, One pair Milliard's Double Headphones 4.000 ohms, iqo ft. Aerial Wire, Lead In Tube, 4 Insulators, Wire for wiring and sleeving, Terminals, V'alve-holder and diagram. Delivered Carriage Paid. Money returned in full, if you are not completely satisfied, within seven days after delivery; full allowance made for parts not required.

G. BUSH, 119, Sutherland Avenue, London, W.9.

POST ORDERS OUR SPECIALITY Satisfaction Guaranteed or Money Refunded PRICE LIST SENT POST FREE

AERIAL WIRE, 100 ft. 7/22 Copper 2'9 HERTZITE CRYSTAL DETECTOR, complete 3/9 BASKET COILS. Seven in Set 4/9 CRYSTAL RECEIVING SET. Entirely enclosed

in Mahogany Cabinet. B.B.C. Royalty paid. Fnlly Tested and Guaranteed. Carriage paid ...32/6 HEADPHONES, Accumulators, Resistances,

Insulators, Vanes, Terminals, Ebonite Parts. Many Other Accessories

CARRIAGE PAID ON 20/= ORDERS

DE LUXE COMMODIT ES 151A. OXt-ORD STREET, LONDON, W.l

>♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦<

ELECTRADIX RADIOS.

IMMEDIATE DELIVERY FROM OVR HUGE STOCKS

Everything from a Recorder to an Earlh Clip. The best equipped City depot.

COME AND SEE US 9, COLONIAL AVENUE is

first opening on left in the Minories, nr. Aldgate Station, Metropolitan Railway.

LESLIE DIXON & CO.,^U 9.COLONIAL AVENUE, MINORIES. E.l.

^Imatcur \yirelas5 70

T. O.

SCIENTIFIC. INSTRUMENT

MAKER

U, GLERKENWELL ROAD, LONDON, E.C.I. ESTABLISHED I8S0. jEX'bibltiOn ZUVatQg—Loi 1862. Sydney. 1879.. Melbourne, 1880.

HMD ■'HONES (ienuine French Telephones, most sensitive obtainable, 6 Tungsten poles in each earpiece. 4,000 ohms with cords (Double Receivers) ... post free

19'6

French " Brunei ■ Headphones 22/c POSTAGE 9d. 4,000 ohms

Variable Condensers CONDENSERS.

Complete Sets of Parts. Assembled Complete" for

Cabinet Mounting. Approx. Capacity Microf'ds.

No. of " Plates, ■ Price.

Approx. Capacity Microfds. Price.

•OOI •00075 •C0O3 •0003 •0002 •odoi

57 ■ 43" 30 19 13 7

7/6 6/9 3,6 4.6 3/6 3/-

•ooi ■0005 •0003 •OOO05

16/. 12/6 11/6 5/6

Postage if- per set extra.

each Bd. each 43d. each 4d. each 3£d. _each 3d.

WIRELESS PARTS AND ACCESSORIES

Aerial Wire, 7/22 bare copper, strandeiJ. Price pet 100 ft., 3/-. By post, 4/6. Aluminium Vanes, 2 doz., 1/-. By post, 1/6. 5/- gross; by post, 6/-. ^ t . .. Basket Coils, 7 iu set, 5/- set. By post, 5/6.

Brass Washers, 2, 3, 4 or 5 B.A. ... ... dozen 2d. „ Nuts, 2, 3, 4 or 5 B.A. ... ... dozen 4d. Brass Rod (Screwed)— 2 B.A., in 12-in. lengths ...

3 B.A/, iu 12-in. lengths - ... ... 4 B.A., in 12-in. lengths ... 5 B.A., in 12-im lengths ...

Copper Foil Sheets, uniform thickness, 12 in. by 3 in ... ... Crystal Detectors on Ebonite. Bach 2/6. By post, 3/-. Also 3/3J by post, 3/9. Crystal Detector, cup enclosed with glass cover, dust ' proof, 4/6. By post, 5/3. ,

Ebonite Dials, with engraved scale 0180, 1/- each. By post, 1/6- . , « Egg Insulators, 4 for 11 d.; 2/6 per doz. By post, 3/6

Filament Resistances. Each 2/6 and 3/6. By post, ' 3/- and 4/-. Filament Resistance.—Suitable for one, two or three

valve sets 4/-. By post, 4/6. A Fixed Condensers, with terminals on ebonite, .0003,

.0005, .001, .002, .005, 1/6; by post, 1/9; 004, 1/9; • by post, 2/-- . . ■ Grid Leak and Condenser, .0003, high quality, 3/9.

By post, 4/3. inductance Coils Wound Enamel Wire, 12 by-4, 3/-. By post, 5/-. i% insulating Sieevingr, 6 yds, for 2/2. By post, 2/6. 12 yds. for 4/-. By post, 4/6. intervalve Transformers (low frequency), tested and guaranteed 5-1, 14/- each. By post, 15/-. , Knobs, with brass nut (2 B.A."), 4^1. each. By post, 7d., 6 for 2/- By post,-2/6. Large. Spacer Washers, 3 doz., 9d. By post, 1/-,

Lead-in Tubes, ebonite, with brass terminals, 9'in., 1/2. By" post, 1/6. 12, in., 1/4. By post) 1/8. Reel Insulators, Id. each. By post. 2/- doz. Slider and-Plunger, 5d. By post, 7d.

Slider Knob, Plunger and, 13 in. rod, 8d. the set. 'Cannot be sent by post.

Small Spacer Washers, 6 doz. 1/-. By post, 1/4. Switch Arms, with, polished knoh,.bushed 2 .B. A. nui:, laminated blade, spring coil washer, nuts and ■bush, 1/-, 1/6, ty- each. By post, 1/3, 1/9, .2/-. Terminals, telephone, with nut and washer, 21- doz.

at By post, 2/6^ Terminals (large).,, aerial and earth, complete with

^2 huts and S washers' (2"B/A'.), 2 for:8d. By Tin- Foil, -free from • lead,-Sheets'26 in.

by 13 in. .,v, .... , ... ^each 4d. War Office Pattern Terminals, vviths hut/and-washed 2/- , doz. By post, 2/6-

66

r thick

EBONITE" Postage Free, Any Size cut.

:: Malt surface s. d. £ s. d.

8x1 7 12 x 10 ... ... 7 6 4x4 ... 1 3 m* si ... ... 9 6 7 x sh ... 2 8 18 X 18 ... ... 12 10

10 x 6 ... 3 9 36 X 18 ... ... 1 30 17 x 5 ... 5 3 7 lb. ... 1 30

Instrument Wires British Made Copper Wires,

Per lb.

S.W. 22

yds. G. per lb. 140

ohms per 1,000 yds. 39

S.C.C. D.C.C. S.S.C. D.S.C. Enmld. 2/9 3/- • 4/- 5/- 2/7

24 230 63 3/- 3/8 4/6 6/- 2/8 26 340 95 3/7 4/1 5/- 8/- 3/2 28 530 140 4/4 4/8 6/- 9/- 3/6 30 716 200 5/- 5/6 7/- 10/- 3/10 32 950 262 6/- 7/3 8/- 12/6 4/2 34 1,300 362 7/- 8/3 9/- 13/6 4/4 36 2,000 530 8/8 10/- 12/- 15/6 4/8

Wireless Crystals " Hertiite " Is. Sd Z incite 6d Silicon Cd Bornite 6d Copper Pyrites 6d Wood's Metal 2s.

— Post free —

Carborundum 6d Molybdenite 6d Iron Pyrites 6d Galena fid Graphite fid

Dram Tellurium 2s fid

Inter valve T ransf ormers

15/- Ratio 5 to 1

Post Free,

Celluloid Accumulators We are introducing a new model consisting jf Jindividual two volt units.. This MODEL to be known as T.g has an actual capacity of. 18 ampere hours, and an intermittent capacity of 34 ampere hours.

PRICE AS FOLLOWS " 2 volt ... 6/-eacfr 4-volt 11/9,, 6 volt 17/6,,

H.T. Batteries, 30 volt, 6/- (by post, 7/6). H.T. Batteries, Co volt, 12/- (by post, 13/6).

Inductance uties Cardboard

12 in. by 4 in., fid each, Posted,

Mahogany Boxes Polished

4i x 4i x Sf ia-, 4l x 4i x 5 in.

. 6J x 6} x 4 " in, 13 x 6 j x 4 in.

Post 3/- 3d 3/6 6d 4/8 1/- 8/- !/-

JANUARY 20. 1923

Notice to Advertisers

ADVERTISEMENT* INSTRUCTIONS find copy for " Ariiateur Wireless" should be at the office by First Post on FRIDAY morn- ing at the latest.

PREPAID ADVERTISEMENTS. B.A. Screws, • Nuts, and Washers, assorted gross,

2s.; list, 2di—J. H. Beniiett, Station Road, WiUesden Junction. ■ t2r

Working Drawings for wiring sketches suppiiea.—- Puckle, Buckhurst Hill, Essex. Telephone, Wood- ford 400. _ [4 s Wireless Goods Cheap .^-Ex-Army transmitters, 15s.; 1 in. spark coils, 8s.; 80-metre sets, transmit- ting, 10s.; mine exploder dynamos, 17s. 6d,—Below. New Goods.—Low-frequency intervalve trans- formers, 16s.; filament resistance, 2s, 6d.; valve- holders, is.; crystal detectors, 2s. 6d. ; switch arms, Is. 9d.; contact studs, 9d. doz.; terminals, Id. and 2d. each; block condensers, Is. 6d. each; variable condensers, .0005, 7s. fid; .0005, 9s.; -001, 12s.; vernier, .00005, 5s.; condenser vanes, Is. doz. pairs. Please call and inspect showrooms. Three days' approyhl against cash.—E, J. Galpin, 16, Loampit Hill, Lewisham, S.E-13, London.- [2 s Potentiometei^-r-Invaluable for- grid control and crystals, adapt an ex-naval rheostat, 260 ohms, 16 stud. Price, Is. 6d., post free; excellent value,— Monk, 4, Alma Road, Plymouth. [3 s "Work" Short Wave ' Receiver, ,£2. Two-slide coiL Perikoii, 9s;' Or exchange valve accessories.— 14, Scoutbottom, Mytholmroyd. [1 s Telephone Receivers Rewound up to 1,000 ohms, 5s.; 2,000 ohms, 7s. 6d. ; cash With order.—M. E. Hamp shire j 139, Sydenham Road, S.E,26. [6r.

Trafford No. 2 Crystal Set, without phones, £2. —Kerr, 62, Farleigh Road, Stoke Newingtph. [5 s

EASY TERMS OR CASH Startling Advertisement Offer, for fourteen days on'y-* Complete Single Valve Set of parts for 99/"« 33/- with order, balance XI/- a •fortnight. " Specification;—Ebonite Panel 10 - 8 drilled, Mullard Ora Valve, Variable Condenser '0005, Filrment Resistance,.Grid Leak-and Con- denser, Two HoneycombColis No. 35 and 30 and Holders, Variable, TT. T. Battery 30 volt, Accumulator 4 volt 30 amps, One pair Mullard's Double Headpnones 4,000 ohms, 100 ft. Aerial Wire, Lead In Tube, 4 Insulators, Wire for wiring and sleeving, Terminals, Valve-holder and diagram. Delivered Carriage Paid. Money returned in full, if you are not completely satisfied, within seven days after-delivery; full allowance made for parts not required.

G. BUSH, 119, Sutherland Avenue, London, W.9.

POST ORDERS OUR SPECIALITY Satisfaction Guaranteed or Money Refunded PRICE LIST SENT POST FREE

AERIAL WIRE, 100 ft. 7/22 Copper 2,9 HERTZITE CRYSTAL DETECTOR, complete 3/9 BASKET COILS. Seven in Set ... ... 4/9 CRYSTAL RECEIVING SET. Entirely enclosed

in Mahogany Cabinet. B.B.C. Royalty paid. Pally Tested and Guaranteed, Carriage paid ... 32/6 HEADPHONES, Accumulators, Resistances.

Insulators, Vanes, Terminals, Ebonite Parts, Many Other Accessories

CARRIAGE PAID ON 20/- ORDERS

DE LUXE COMMODITIES 151 A, OXFORD STREET, LONDON. W.l

EIECTRAD1X RADIOS.

IMMEDIATE DELIVERY FROM OUR HUGE STOCKS

Everything from a Recorder to an Earth Clip. The best equipped City depot.

COME AND SEE US 9, COLONIAL AVENUE is

first opening on .eft in the' Minories, nr. 11 Igate Station, Metropolitan Railway.

LESj .IE DIXON & CO.fAt™Us 9,COLONIAL AVENUE. MINORIES. E.l.

Page 24: Amateur Wireless Magazine, Weekly, Sat 20th January 1923...Amateur Wireless Magazine, Weekly, Sat 20th January 1923. DONT MISS FREE MAP WITH CALL SIGNS NEXT WEEK Vol. 11, No. 33 SATURDAY,No

JANUARY 20. 1923 71 ^moteur ^i«les5

Jutkeflfam Qenaidvke tkePwUm

Use a stage or two of H.F. with

a Frame Aerial and you'll get the

long-distance Stations just as well.

The man who cannot erect an outside Aeriai or who wants to move his Set from room to room need not despair. A good Frame Aerial of the type illustrated will give loud and clear telephony when used with sufficient H.F. amplification from all Stations within a wide area. Further, because it is directional, it cuts out a lot of interference from near-by Stations together with most of the atmospherics. The Peto-Scott standardised Unit System provides the only sensible way of adding just as many stages of PI.F. as you need at the least possible expense.

Our illustrated Booklet, "Radio," describes the whole System and shows how each Unit is built up—price Cd., post free.

PRICE LIST of Sets of Parts

^o. i. Tuner Unit 27/6 •no. 2. Condenser Unit 42/-

No. 3. H.F. Amp. Unit 13/6 No. 4, Detector Unit 17/6 No. 5. L. F. Amp, Unit 33/6

Mahogany Cabinets to fit Nos. x, 3, 4 and 5, 3/6. To fit No. 2, 7/-.

Postage gd. per unit extra, hit paid on all orders over £2.

The PETO-SCOTT Co

64. HIGH HOLBORN W.C.I

MARSHALL AD

Wireless is attracting all men. ■ The Amateur is entering the field in great numbers, and be wants to know all about it. He will require Materials, Parts, Tools. He will also want to sell surplus material.

u AMATEUR WIRELESS" is out to cater for this class of reader, who will be eager for knowledge and bargains. To meet him, use the Sale and Exchange columns, which he is sure to search. Rate 3d. per word, 3s. minimum, prepaid, Latest date Friday mornings.

Address .* The Advertisement Manager, "Amateur Wireless," La Belle Sauvage, Ludgate Hill, London, E.C.4.

GENTS'

RADIO FITMENTS STURDY, SOUND AND RELIABLE

SEND for LA TEST PRICES OF Gents' " TANGENT " Filament Rheostat Gents' " TANGENT" L.F. Transformer Gents' " D1SC0L " H.F. Transformer

and other Ctments. Radio Dept.,

"FARADAY WORKS," GENT & CO., LTD., London: 2b, victoria^t., s.wl NEWCASTLE-ON-TYNE ; " TANGENT HOUSE, ' BUAOKETT ST,

LEICESTER

.WvXXILAVWj

m

PHENOMENAL/ VALUE

TRANSFORMERS—Telephone, 15/-; L.F. Intervalve, £1 H.F. INTERVALVE TRANSFORMERS—

Terminal Pin Unmounted Unmounted Wave Length 800— 700 M. 600—1300 51. 900—1900 M. 1800—3500. M. 3000—5000 M.

Type 3/9 4/- 5/- 5/6 6/6

Type 4/6 4/6 5/6 6/- 71-

Slab Basket 1/3 ... 1/3 i/6 ... 1/6 2/- ... 2/6 2/6 ... 3/- 3/6 ... 4/-

FILAMENT RESISTANCES—Specially good quality, 2/6 CONDENSERS FIXED—All Capacities, 1/6 GRID LEAKS, 1/-. GRID LEAK AND CONDENSER—Best quality, 3/9 VALVE HOLDERS, 1/- ENAMELLED AERIAL WIRE—Per 100 ft., 4/9

Charge your own Accumulators from A.C. Mains— NO DANGER! NO VALVES! HIGH EFFICIENCY!

OUR ECONOMICAL ROTARY BATTERY CHARGER RECTIFIES A.C. TO D.C. Complete with Starting Switch and Auto Transformer to run off 100/250 volt 50/60 cycle single phase mains. Output—8/15 volts 3 amps.

Special Price O O COMPLETE LIST of all Kadio Essentials in preparation. Meanwhile

let us have your inquiries. Nothing too small; nothing too large ! Orders of £1 and over post paid; below include postage

All Post Orders: Dept. A, 10, MANOR GARDENS, PURLEY, Surrey

Off ICES' J0-MAMoR GARDENS' BRIGhUn R0AD • * PUHLEV iRiMiir («N» CR^rDPN:-

JANUARY 20. 1023 71 ^nujteuf ^fiwUss

MCtkSh'me. QawCtefaetke'PwIjlm

Use a stage or two of H.F. with

a Frame Aerial anc yoiTll get the

long-distance Stations just as well.

The man who cannot erect an outside Aeriai or who wants to move his Set from room to room need not despair. A good Frame Aerial of the type illustrated will give loud and clear telephony when used with sufficient H.F. amplification from all Stations within a wide area. Further, because it is directional, it cuts out a lot of interference from near-by Stations together with most of the atmospherics. The Peto-Scott standardised Unit System provides the only sensible way of adding just as many stages of H.F. as you need at the least possible expense.

Our illustrated Booklet, *' Radio," .describes the;whole System and shows how, each Unit is built up—price 6d., post free.

PRICE LIST of Sets of Parts

Jo. i. Tuner Unit 27/6 no. 2. Condenser Unit 42/-

No. 3. H.F. Amp. Unit 13/6 No. 4, Detector Unit 17/6 No. 5. L.F. Amp. Unit 33/6

Mahogany Cabinets to fit Nos. i, 3, 4 and 5, 3/6. To fit No. 2, 7/-.

Postage gd. per unit extra, but paid on all orders over £2.

The PETO-SCOTT Co., 64, HIGH HOLBORN,

W.C.I

Wireless is attracting all men. ■ The Amateur is entering the field in great numbers, and he wants to know all about it. He will require Materials, Parts, Tools, He will also want to sell surplus material.

u AMATEUR WIRELESS " is out to cater for this class of reader, who will be eager for knowledge and bargains. To meet him, use the Sale and Exchange columns, which he is sure to search. Rate 3d. per word, 3s, minimum, prepaid. Latest date Friday mornings.

Address .* The Advertisement Manager, "Amateur Wireless,'1

La Be Me Sauvage, Ludgate Hill, London, F.C.4.

V-XAXILAVW 44j-VLrW,

PHENOMENAL/ VAi^CJE

GENTS'

RADIO FITMENTS STURDY, SOUND AND RELIABLE

SEND jot LA TEST PRICES OF Tents' ' TANGENT " Filament Rheostat Gents'" TANGENT " L.F. Transformer Cents' '* DISCOL " H.F. Transformer

and ether Giments. ttadio Dept..

" FARADAY WO_v SS." GENT & CO., LTD., London as, .victoria ^sr., s.wl >>- NEWCASTLE-ON-TYNE ! TANGENT HOUSE, Bt-AOKETT ST,

LEICESTER

TRANSFORMERS—Telephone, 15/-; L.F. Intervalve, £1 H.F. 1NTERVALVE TRANSFORMERS—

Wave Length 300— 700 M. 600—1300 Jr. 900-1900 M. 1800—3500. M. 3000—5000 M.

Pin Type 4/6 3/9 4/6 5/- 5/6 S/G 6/G 71-

Unmounted Unmounted Slab Basket 1/3 ... 1/3 1/6 ... 1/6 2/- ... 2/6 2/6 ... 3/- 3/6 ... 4/-

FILAMENT RESISTANCES—Specially good quality, 2/6 CONDENSERS FIXED—All Capacities, 1/6 GRID LEAKS, 1/-. GRID LEAK AND CONDENSER—Best quality, 3/9 VALVE HOLDERS, 1/- ENAMELLED AERIAL WIRE—Per 100 ft., 4/9

Charge your own Accumulators from A.C, Mains— NO DANGER! NO VALVES! HIGH EFFICIENCY!

OUR ECONOMICAL ROTARY BATTEfiY CHARGER RECTIFIES A.C. TO D.C. Complete with Starting Switch and Anto Transformer to run off 100/250 volt 50/60 cycle single phase mains. Output—8/15 volts 3 amps.

Special Price £7 .O O COMPLETE LIST of. all Radio Essentials in preparation. Meanwhile

let us have your inqriirxes. Nothing too small; nothing too large! ~ Orders of £1 and over post paid; beloto include postage

All Post Orders: Dept. A, 10, MANOR GARDENS, PURLEY, Surrey

Offices < BRfcHtTt R'AO* • » PURLEV' IMIU mum

CR-YDPfV f •

wMv>^/vbX ^

Page 25: Amateur Wireless Magazine, Weekly, Sat 20th January 1923...Amateur Wireless Magazine, Weekly, Sat 20th January 1923. DONT MISS FREE MAP WITH CALL SIGNS NEXT WEEK Vol. 11, No. 33 SATURDAY,No

^mabiur 72 JANUARY 20. 1923

No. R. 1238. ■ Manufactured, under Erowii I'ate'nt o. : 34303/1,3 by Sole Licence.)

DEPENDABLE HEAD 'PHONES

Write for literature and prices of these instruments and of the wide range of other radio apparatus

which we offer.

YOU can always hear well with Sterling Head 'Phones. They are constructed on

highly scientific principles and embody the very best workmanship and finish.

The ear pieces have swivel and trunnion movement, which provides a comfortable fit to the ear of the user.

The Ladies' Hand 'Phone illustrated has been designed to give the greatest ease and con- venience and enables ladies to listen-in without disarranging their coiffure.

To he obtained from all Dealers or direct from:

STERLING TFLF.PHONE & ELECTRIC CO. LTD. Telephone House,

210-212, TOTTENHAM COURT ROAD, LONDON, W.l Telephone: Museum*1144 (7 lines). Telegrams: "Cucurais. Wesdo, London."

MANCHESTER: 14, St. Peter's Square CARDIFF : 8, Park Place NEWGASTLE-ON-TYNE:

9, Clavering Place WORKS: Dagenham, Essex,,

1

No. 1281. RADIO

LADIES' HAND 'PHONE (Manufactured under Brown's Patent No. 134353/18 by Sole Licence)

We guarantee that all Broadcast Radio Apparatus sold by us conforms with the conditions of the Broadcaster's licence issued by the Postmaster-General,

jtninnnnTTHiiTnrmtumni'.urnTnnmiu niivrntTTuirrt

{pifkoui QM-

The " Ducon" does away with the Aerial. Plug one into an ordinary electric lamp holder or wall socket, connect to your wireless receiver and you will receive the broadcasting perfectly. The Ducon" can be used with complete safety—each one is tested to 2,500 volts, ■it consumes no current, and does not affect the electric light in any way.

is obtainable from leading wireless dealers, electrical contractors, and stores, or direct : from the makers.

Over 50,000 in use. Dealers not yet stocking are invited to write ; for trade terms.

THE DUBILIER CONDENSER CO. (1921) LTD., | Ducon Works, Goldhawk Kd., Shepherd's Bush, London. ;

Telephone: Ilavnnersfnith 1 Telegrams: Hwollcon, Phone London, M n M i t . n n n U U u.l 1 pm I iU.i HU U n U UM l> I n > M r

!.»

yii 1

ST 5 ' ^

A T s ' gl!

Printed and Published in England by Cassell & Company, Limited, Lud gate Hill, London, E.C.4. Sole Agents for South Africa, Central News Agency. Limited. Saturday, January 20, 1923

Httuutur ^/uules^ 72 jaNUARY 20. 1923

DfiPEHDABL^ HEAD 'PHONES

No. R. 1238. Manufactured, under .Urowii^ Patent o. 134353/13 by Sole Licence.)

Write for literature and prices of these instruments and of the wide range of ether radio apparatus

which we offer.

YOU can always hear well witn Sterling Head 'Phones. They are construded on

highly scientific principles' and embody •• the very best workmanship and finish.

The ear pieces have swivel and trunrnon movement, which provides a comfortable "fit to the ear of the .user.

The Ladies' Hand 'Phone illustrated has been designed to give the greatest ease and con- venience and enables ladies to listen-in without disarranging their coiffure.

To be obtained from all Dealers or direct from:

STERLING Tr LEPHONE & ELECTRIC CO. LTD. Telephone House,

• 210-212, TOTTENHAM COURT ROAD, LONDON, W.l Telephone: Museum 1144 (7 lines). Telegrams: "Gucumis, Wesdo, London."

MANCHESTER; 14, St, Peter's Square GARDIFE: S, Park Place

NEWCASTLE-ON-TYNE: 9, Glavering Place

WORKS: Dagenham, Essex.,

No, U, 1281 RADIO

LADIES' HAND 'PHONE (Manufactured under Brown's Patent Ko. 134353/18 by Sole Licence) 1

We guarantee that all Broadcast Radio Apparatus sold by us conforms with the conditions of the Broadcaster's licence issued by the Postmaster-General*

jiiiiiiMiiiiiuiuiininiiiiiiiiiiimiiiniiiiii iiiiiiiiiirui.iii.

JsHxeiaS#

mfkouC ok.

The "Ducon" does away witlv the Aerial. : Plug one_ into an ordinary electric lamp : holder " or wall socket, connect to your : wireless receiver and you will receive th broadcasting perfectly. The ""Duconcan be used with complete Y safetjt—each one is tested to 2,500 volts, : it consumes no current, and does not affect : the electric light in airy wa}^.

^ ©y (g@K] o@/=

is obtainable from leading wireless dealers, electrical contractors and stores, or direct : from the .makers.

Oner 50,000 in use. Dealers not yet stocking are invited to write ; for trade term's

THE DUBII sER CONDENSER CO. (1921) LTD., i Ducon Works, Goldhawk Rd., Shepherd's Bush, London, :

fj : ^ 'x-

Telephone : H'ammerhnith 1 - ^ ^ Telegrams: HivoUcott) Fhone London.

t,/;'

,1 1 ■ n . 11111 ■ 11 n n : 1 :TtJ:i 111111111 n 111: i n 111 ■:. ■. r

51- !

Printed, and Published in England by Cassell & Company, Limited, Lud gate Hill, London, E.C.-f. Sole Agents for South Africa, CfiNTSAL News Agency. Limited.. Saturday, January so, 1923