N THIS ISSUE - worldradiohistory.com · satisfies customers and brings them back for more, year after yfar, the reason is simple. "It's quality. Quality and value that stand out

;.;

N THIS ISSUE:

ervicing Sound I -F Stages in

Modern Electronic VOM

TV Truck Solves Installation

Servicing Phot ctric Equi

T

and FM R

DECEMBER1949

-FM-TV-SOU

r

Discover a Newand Richer Market

with...

The Mallory MidgetrolThe first "As" diameteReplacement Control Lin

How much business did you let slip through your fingers last year? Goodbusiness! Big business! All because you couldn't get controls small enough toservice personals, portables and auto radios!

This year, discover how profitable these jobs can be. Stock up on the 1W'Mallory Midgetrol and discover more business with a lower inventory!

WIDER APPLICATION-The small size lets you service portables, auto radiosand small AC -DC receivers requiring controls.

SIMPLER INSTALLATION-The new and unique flat shaft design of the MalloryMidgetrol saves installation time with all types of knobs.

LESS INVENTORY-Electrical characteristics allow you to use the MalloryMidgetrol to replace 1N" as well as %" controls. Since no special shafts are required,you carry fewer controls in stock.

NEW FEATURES NEW FEATURES!NEW SIZENEW DESIGN

NEW SHAFT NEW SWITCHNEW EXTENSION NEW ELEMENT

NEW TWO -POINT SUSPENSION

NEW CONTACTNEW TERMINAL

Don't Miss the Mallory Television Service Encyclopedia.Get Your Copy From Your Mallory Distributor . . . Only 35c!

MALLORCAPACITORS . . . CONTROLS . . . VIBRATORS . .

SWITCHES . . . RESISTORS . . . RECTIFIERSVIBRAPACK* POWER SUPPLIES... FILTERS

*Reg. U. S. Pot. Off.

APPROVED IPREcISION PRODUCTS.P. R. MALLORY & CO., Inc., INDIANAPOLIS 6, INDIANA

Television Arithmetic

$200 Television Set $5 Antenna = $5 Picture$200 Television Set + $25 Antenna = $225 Picture

Yes ... it's as simple and basic as that. Just like 2 plus 2 equals 4. Let allof us square up our thinking and recognize OPENLY that in a great,great majority of cases, the television buyer can get the full value fromhis set ONLY with a good outdoor antenna properly installed.

Certainly, there is great value for the indoor antenna. We make themourselves, and good ones, too, BUT ...

We'll be the first to admit that the best indoor antenna cannot comparewith even the poorest outdoor antenna for picture quality. In certain"ideal" conditions, an indoor antenna will perform satisfactorily, BUT...

Let us not abuse this "condition" by recommending indoor or "built-in" antennas where they will not give the customer his full dollar'sworth. It is up to the Television Industry to see that the AmericanPublic gets its money's worth in television and that means simply ... AGOOD OUTDOOR ANTENNA SHOULD BE INSTALLEDWHEREVER POSSIBLE.

The indoor antenna is a good short cut to quick consumer sales, BUTDOES NOT GIVE THE CUSTOMER THE PICTURE HE ISPAYING FOR! This is the truth about television antennas ... asrelated to picture quality. Tell it to your customers, let them decidefor themselves.

THE MAKERS OF THE COMPLETE LINE OF GOOD TELEVISION ANTENNAS

THAT MAKE GOOD TV SETS EVEN BETTER!

THE RADIART CORPORATION CLEVELAND 2, OHIO1%20

Reprints of this advertisementavailable upon request.

RADIO SERVICE DEALER DECEMBER, 1949

TWO STANDOUTSfrom the

OUTSTA DING LINE

CHANNEL MASTER'SFAN -ELECTOR

This sensationalnew preassembled antenna,

the Fan-Flector, a development ofChannel Master's research laboratories,

is the most sensitive all -channel antennadeveloped to date.

No high band attachments.No multiple lead in wires.No wasted assembly time.

Dealer after dealer has made his most difficultfringe installations stick

with the Fan-Flector,America's fastest selling antenna.

ListBM312 Fan-Flector 13.75BM312X2 Stacked Fan-Flector 29.30BM312X4 Double Stacked Fan-Flector 63.25

S ACKED FAWN CTORCONVENTIONAL STACKED CON CAL

crukraNit 2 3 4 5 6 7 8 9 10 11 12 1350 60 70 80 90 180 190 200 210FREQUENCY-NM

HORIZONTAL POLAR DIAGRAMS GAIN CURVESLow band front -to -back ratios between 3 and 4 to 1. "Most popular" conventional stacked conical antennaLobe width decreases on high band for ghost -free (broken lines) compared to the stacked Fan-Flectorreception. Vee-Beam engineering minimizes side lobes. (solid lines).

TO: CHANNEL MASTER CORP., ELLENVILLE, N. Y.Please send me:

Name of nearest Channel Master DistributorLi Technical data and literature

YOUR NAME

COMPANY NAMEADDRESS

CITY STATE

DEPT. D-12

2 RADIO SERVICE DEALER DECEMBER, 1949

CHANNEL MASTER'SHIDEAWAYTHE DISAPPEARANCEOF A BUILT-IN ANTENNA

withTHE PERFORMANCE OFAN OUT -DOOR ANTENNA

Channel Master's exclusive Multiflex Action*enables this antenna to be hiddenaway behind the set when not in use.The elements can be arranged toform a horizontal Vee for any channel inany direction thus increasing the gain.

The hand rubbed hardwood surfaces,nickel plated metal components and smartdesign makes the Hideawaythe most attractive indoor antennaon the market today.

LIST 975available in blond,mahogany andwalnut

*Pat. Pend.

RADIO SERVICE DEALER DECEMBER, 1949 3

EDITORIALby S. H. lOWANi

Beware of BargautsThe Deceie, de of McCall's Reabook

has an article "How Cheap Can It C,that teaches a worthwhile lesson. Too n,,of u, try to buy things beeause a fncan --get it wholesale" or we pewee,"discount" houses that seem to offer bettervalues than regular supply channels.

Genuine bargains art seldom, if eyer.offered by discount houses. There's a bigdifference between what seems to be abargain and a genuine one. Take radiotubes and parts for example. Common-sense should forewarn us that the so-called"bargains" being offered through advertis-ing in the newstand type radio magazinescannot be, in most cases, all that is claimedfor them. There never was a truer adagethan that oldy "Cheap is Cheap." If youwant to play safe (and good businessmenalways try to do so), stick to standard,nationally advertised brands obtained fromyour regular legitimate supply house. Allstandard merchandise whether it be tubes.replacement parts, accessories or test equip-ment, has manufacturer's warranty, con-formity to specifications and dependability.Experience will prove standard merchandice to he better buys than "bargains."Business Trends

Business conditions and earnings in theradio -TV field are, according to latestindices, holding steadily on a slightly upward plane. Dumping has dropped toalmost zero; price -cutting amongst retail-/ -

is less rampant; service -fees are quistabilizing at profitable levels. Thefusion caused by different speed phonorecord makers has passed further into thebackground and now people are buying orare having repaired in ever-increasingquantities radios and record players andplayer attachments. It appears as thouel,1950 will be a good year, better than 194or 1949, and both were pretty good. don'tyou agree? And now, before I forge,"Happy Holiday and a ProsperousYear" to you all.Looking Ahead

The f ,,munications Comm,hearings on LID and color TV are stilt 1,

progress. The general concensus of thosewho are "in the know" is that because thesubject is so complex FCC will hold toconservative status quo position for 111J.

months.Full details regarding New York sr,

Pennsylvania's two -state Preventive Radi,Maintenance Month Campaign, held i,October, are still too meager to warrarreporting, other than that radio servicin.'business and earnings in the two states werewell ahead of normal. In fact, the ranipaign was successful enough to justify in,mediate planning for another on a nationalbasis for 1950. To get the ball rolling itthis regard it seems advisable for all independent service firms to arrange immediately for closer tie-ups with servicemen -

associations. Stated another way, if You ar.not already a member of some radioman'-ass.eciation, join one pronto.

Sanford R. (mianEDI I on P1111_11411:111

Samuel L. MarshallNIAN AGING EDITOR

MI/ 1. PI III 1111111\111. 4 it -p.34_ \i 1!\1

NEW YORK 17, N Y.

ft 4,1. 10 N.. 1

111 I I It 19 4'1

Editorial

Trade Flashes

Servicing Sound I -F Stages in TV and F -MReceivers, by Matthew Mandl

A description of various types of scunJi-f stages and servicing techniques.

Modern Electronic VOM, by Allan LytelA popular electronic vom is explainedtogether with its applications.

Servicing Photo -Electric Equipment, Part 2, byWilliam R Wellman

Con. wawg ,r1,tal?ment of this article. Servicinginformation and adjustments, are presented.

TV Truck Solves Installation Problems, by I. Shyke''yn interesting example of how a dealer exploiteda good idea with an attractive truck.

Circuit CourtPhilco Model 49-1606, Masco Model MA 2k._

Shop NotesCleaning condensers. Westinghouse Model H -217 -ground connection to Aquadag. Repair loosenedtubes. Utility heater. Bendix a -c d -c chassistube failures. Admiral 49C8-2 tuners-frequencydrift. Motorola VT 71 repair. G. E.-exchangincistylus. Admiral Model 30-interference. Tube-ba--connectors. Delco a-c5d-c portables-hum.

New Products

Association News

SANFORD L. CAHNNational Advertising Sales Manager

JEAN M WHEELER Circulation ManagarBRANCH: J. C GALLOWAY 816 W. 5th St.,

18

IV

20

7 ?

HARRY N. REIZESAdvertising Manager

DAVID SALTMAN Production ManageLot Angeles 13, Calif., Mutual

RADIO SERVICE DEALER is published monthly by Cowan Publishing Corp., 342 Madison .-N. Y. 17. N.Y. Subscription price: 32 per year in the united States, U.S. Possessions & CkL.6.1elsewhere 13. Single copies: Ebe Entered as second class matter Dee. 18 1948 at the Po,c York, N.Y. Lrl.,- AI


"NO BETTER TUBES SOLD

id THAN KEN-RAD TUBES

-SALES PROVE IT!"

0. 8. CONLEY and H. T. CONLEY, ConleyRadio and Electrical Shop, Corinth, Miss., likethousands of servicemen, have increased turn-over, boosted profit by pushing high -qualityKen-Rad Tubes.

"NO BETTER TUBES MADE

THAN KEN-RAD TUBES

-TESTS PROVE IT!""I help make Ken-Rad Tubes. And I know-there areno better tubes made!"Ken-Rad Tubes have to prove their quality over andover again at every stage of production."On the right, a Ken-Rad Tube is receiving the micro -phonic and noise check, with the aid of an amplifierhaving a known response and a specified gain. Thetube is tapped by a motor -driven tapper, and theresulting audio output is checked on a standard VUmeter."This is only one of the numerous quality tests Ken-Rad Tubes must pass before being shipped to you."Good? They've got to be good!"

KENRADPRODUCT OF GENERAL ELECTRIC COMPANY

Schenectady 5, New York


"Ken-Rad Tubes have been a steadyseller for us ever since we started inbusiness."Now, I don't pretend to be a mer-chandising expert-but when an itemsatisfies customers and brings themback for more, year after yfar, thereason is simple."It's quality. Quality and value thatstand out."Ken-Rad Tubes sell fast, stay sold be-cause you can't beat them on eithercount."

MOB_ERT f. MQE, Division Engineer,en- ad plants, is one of many experts

who help direct the testing of Ken-RadTubes. Besides noise and microphonics,these quality tubes are checked forstatic characteristics, life, shorts, appear-ance, gas, air and hum.

THE SERVICEMAN'S TUBE... backed by profit -mak-ing sales aids which yourKen-Rad distributor will beglad to show you. Phone orwrite him today!

5

For YOUfrikn.-410,ilE

YOU:

Monty s Worth

is GOODRADIO AND1E1.6 VISION

Servica

Gives customers a newappreciation of yourservice facilities

Helps you avoid "cut-throat" price competition

"Your Money's Worth in GoodRadio and Television Service" isthe title of this new 16 -page book-let now made available by the mak-ers of Sprague Capacitors andKoolohm Resistors for distribu-tion to your service customers andprospects under your own name!

Profusely illustrated, finely lith-ographed in two colors, the book-let will help you win customers,justify fair service prices and meet"cut throat" competition that isspringing up on all sides. It tellsset owners about the complexitiesof today's radio and televisionequipment and about the extensiveservice facilities needed to keep re-ceivers in first class working order.

In short, it is a book designedto win confidence for you by show-ing customers how complicatedthe work really is and by provingto them exactlyhow and whygood servicework com-mands a fairprice,.

rMINI Mill MIN MN

I

I

I

I

I1.

Write for

FREESAMPLE

Dept. RSD-129, Sprague Products Co.North Adams, Mass.

Please rush free sample of the new booklet"Your Money's Worth in Good Radio and Tele-vision Service" and tell me how I can obtainadditional copies for distribution to my servicecustomers.

Nome

Address

City, Zone, State

TRADEFLASHESA "press -time" digest of production,distribution & merchandising activities

TV ShipmentsWashington, Nov. 25-RMA mem-

ber -companies reported shipments of503,352 television receivers to 49 citiesand a few unspecified areas during thethird quarter of 1949, the Radio Man-ufacturers Association reported recent-ly. At the beginning of October2,209,724 television receivers had beenshipped to these same areas.

Sylvania Promotes Servicemen-Public Goodwill

Sylvania Electric Products, Inc.,radio division, will continue to pro-mote radio and television servicemenduring 1950 in a new series of nationalads in the Saturday Evening Post,Life, Look, Collier's, and RadioTelevision Best, scheduled to start illJanuary.

Sylvania will supplement the adswith a cooperative campaign kit forservicemen and dealers which includesfour-color window posters based onthe monthly ad, two-color streamers,three -color postal cards, free mats forlocal newspaper advertising, and radiospot announcements.

RCA Multiple Outlet TVAntenna System

RCA announced recently the sign-ing of three separate contracts forthe installation of multiple outlet TVantenna systems in three large NewYork apartment projects, with an ag-gregate of 1,000 apartment units. Thecontracts for the RCA TelevisionAntenaplex Systems were placed withthe Commercial Radio Sound Corp.,RCA's sound products representativein the New York Area.

New Needle PackageDuotone Company, Inc., 799 B'way,

N. Y. 3, N. Y., announces the avail-ability of replacement needles for mostof the popular cartridges. Introduc-tion of this new addition to the Duo-tone Line is being made through aspecial Service -Aid -Kit which containson each of fourteen (14) differenttypes of needles enclosed in a metalstorage case.

Rider Receives Educational AwardJohn F. Rider, president of the pub-

lishing company bearing his name,was the recipient of an award tenderedby the Empire State Federation ofElectronic Technicians Associations.Samuel 1.. Ed uc:i ti Diree-

for and Managing Editor of RadioService Dealer, made the presentationon November 12, 1949, at the RadioTechnicians' Guild of Rochester, N.Y.,banquet held at Locust Lawn, Ionia,New York.

Aerovox Acquires Elec. Reactance Co.The purchase of the entire outstand-

ing stock of Electrical ReactanceCompany by Aerovox Corporation ofNew Bedford, Mass., is announced byW. Myron Owen, Aerovox president.

Town Meetings ProgressProgress in education of radio and

television technicians has been ad-vanced five year by "Town Meetings"of Radio Technicians, R. C. Sprague,chairman of the Radio ManufacturersAssociation's "Town Meetings" Com-mittee, told a Washington "TownMeeting" recently in the U. S. Cham-ber of Commerce.

The Washington "Town Meeting,"the seventh to be held in two years,was sponsored jointly by RMA andthe Washington Electric Institutewith the cooperation of local set and


SYLVANIA RADIO TUBES.inherited Dealer

LOOK FOR NIS

SIGN OF DEPINDABIE

RADIO SOME

Does your radio give out with squeals and grunts? Thencall the serviceman who displays the Sylvania sign. Becauseyour radio needs expert care, the kind this fellow is trainedto give. He has Sylvania test equipment to root out troublespots ... high -quality Sylvania radio tubes to bring you thecrystal-clear reception you want. Hear your old set performas it did the day you bought it. Get it fixed at the Sylvaniasign of dependable service.

SYLVANIARADIO TUBESPRODUCT OF SYLVANIA ELECTRIC PRODUCTS INC,

STLVADIA RADIO TUBES'',Authoiized Dealer.

...and YOU cando the same byACTING NOM

Another of Sylvania's famous profit -building campaigns is getting under way!The campaign runs through the months of January, February, March andApril-with half -page ads like this in LIFE, THE SATURDAY EVENING POST,LOOK, COLLIER'S, and RADIO AND TELEVISION BEST. The ads tell your cus-tomers and prospects to come to you for radio and television service.

But that's just the start! THEN ... you tie in with this national advertisingby using Sylvania's complete kit of display and direct mail material-all builtaround the ads-designed for you-and ready for you now!

Sylvania's previous campaigns paid off in a big way for thousands of dealersand servicemen. Be ready to cash in on this latest big push!

HERE'S WHAT YOU GET IN THE SYLVANIA KIT:

T

O POST CARDS. You get 4 sets ofPostal Card Mailings-one foreach month in the campaign.They're in 3 colors-imprintedwith your name and address!You pay only the governmentpostage on each card-that'sall you pay for the entire kit!EVERYTHING ELSE IS FREE.

0 AD MATS. You get 4 NewspaperAd Mats-two sizes for each 2 -month period. Sizes are oneand two columns wide, 7 inchesdeep. Easy way to tie your localnewspaper advertising in withSylvania's national ads!

DECALS. You get as manyDecals as you need-in 8or 12 inch diameter.Your choice of wording-RADIO SERVICE orRADIO TELEVISIONSERVICE. Sylvania's adsmake these Decals na-tionally known-cash inon their familiarity!

,,,,.._;-,,your tads

'needs

flair

CAinit

r -

We use and

recommend SYLVANIA

Radio and TelevisionTubes

@WINDOW DISPLAYS. You get 2 WindowDisplays-featuring the same illustra-tions as the Sylvania national ads. 3 -dimensional -4 colors -2 by 3 feet. 2COUNTER CARDS, too, 12 by 18 inches.

0 STREAMERS. You get 2 Window Stream-ers-in 2 colors -11 by 26 inches. Likethe other items in the campaign,Streamers feature both radio and tele-vision service.

0 RADIO SPOT ANNOUNCEMENTS. You get 4 booklets of Radio SpotAnnouncements-one for each of the 4 months in the cam-paign. When you've planned your schedule, just hand thespots to your local radio station-they're all ready to use!

Mail coupon today for full details on the complete campaign!

Sylvania Electric Products Inc.Advertising Dept. R-1812, Emporium, Pa.

Please send full details of your new 1950 January, February,March and April Service Dealer Campaigns.

NAME

COMPANY

ADDRESS

CITY ZONE.... STATi

YLVANIM/ELECTRICRADIO TUBES; CATHODE RAY TUBES; ELECTRONIC DEVICES; FLUORESCENT LAMPS, FIXTURES, WIRING DEVICES, SIGN TUBING; LIGHT BULBS; PHOTOLAMPS


r

Ole 4MENEM MMMID

means more business for youRCA 195-A STANDARD VOLTOHMYST*

C-Ruheita SlopTV, FM, AM, and PA service require themodern features designed into the RCA195-A Standard VoltOhmyst.

The 195-A measures dc and RMS acvoltages up to 1000 volts, resistancevalues from 0.1 ohm to 1000 megohms,and decibel values (db, vu, or dbm) from-20 to +52.

Its dc input resistance is 10 megohmson all ranges. Zero -center indication isavailable for FM work. The ac inputresistance is 200,000 ohms.

An isolating resistor in the dc probepermits dc voltages to be measured with-out disturbance of high -impedance high -frequency ac circuits.

When the 195-A is used with theaccessory RCA Crystal Probe WG-263, rfvoltages can be measured up to 100 Mc.With accessory RCA High -Voltage ProbeWG-288, de voltage can be measured upto 30,000 volts.

An electronic bridge circuit protectsthe meter movement against burnout.

I 0 1

RCA WV -65A BATTERY VOLTOHMYST*

54-"Pcpwv.d. tite74teekHere is a portable electronic meter whichmeasures dc and RMS ac voltages up to1000 volts, dc current from 0.3 ma to 10amps, and resistance values from 0.1ohm to 1000 megohms.

The self-contained battery power sup-ply lasts up to 10 months in normalservice.

The WV -65A is supplied with an isolat-ing resistor in the de probe, and can beused with accessory RCA Crystal ProbeWG-263, or with accessory RCA High -Voltage Probe WG-284.

The dc input resistance is 11 megohmson all ranges. This instrument will meas-ure avc voltages, detect leaky couplingcapacitors, and can be used to trace syncand deflection voltages in TV receivers.

At the sensational price of $59.50, theRCA WV -65A is your best buy for serviceof two-way car radios, farm sets, marine,airplane, railway, bus, and theatresound equipment.*Trade Mark "VoltOhmyst" Reg. U. S. Pat. Office

See your RCA distributor for further details about these famous electronicmeters, or write RCA, Commercial Engineering, Section 55LX, Harrison, N. J.

See Your RCA Distributor For Test Equipment You Can Trust

RAD/0 CORPORATION of AMERICATEST AND MEASURING EQUIPMENT HARRISON. N.

parts distributors. Each of the threenight sessions - Tuesday throughThursday-was attended by 800 ormore service technicians-the largestsuch assembly ever held in the nation'scapital.

Astatic Reaches Public DirectAnother company might have known

what to expect, but Astatic was takencompletely by surprise when lettersstarted recently to pour in from thepublic, from all sections of the coun-try. Reason for the sudden friendlyattitude from "just plain folks" isAstatic's introduction of its ChannelChief, Model AT -1 Television Booster-a product that not only marksAstatic's first entry in the Televisionfield, but the first Astatic product ofgeneral application to hit the marketwith the company name in plain sight,visible to the user at all times.Oxford Appoints Jobbers

Oxford Electric Corporation, 3911So. Michigan Avenue, Chicago, Ill.,manufacturers of the well knownOxford Speakers, have announcedtheir entry into the jobber speaker re-placement field. A complete packagedline of P.M. and E.M. speakers willbe available to the Jobber Trade on orabout January 1, 1950.RCA Pict -o -Guide No. 2

A second volume of the RCA Tele-vision Pict -O -Guide, containing trou-ble -shooting photographs which enablethe serviceman to locate television -receiver troubles by the "picture anal-ysis" method, has been announced bythe RCA Tube Department.G. E. Shows Lab Equipment

General Electric's full line of lab-oratory equipment, including powersupplies, oscilloscopes, sweep andmarker generators and tube analyzerswas displayed and demonstrated re-cently at Sun Radio and Electronics,Inc., or New York City, for a fullweek.

Philco TV JigsConsistent reliable alignment of TV

sets requires the use of alignment jigs.A group of alignment jigs has beendesigned for Philco television receiv-ers, to be used with practically anymake of test equipment, which permitthe serviceman to do a much betterand faster job, thus reducing call-backs which usually result in consid-erable customer dissatisfaction and aloss of profit to the serviceman.Rider TV 3 Available

John F. Rider Publisher, Inc., 480Canal Street, New York 13, N. Y.,announces the availability of the newTV Manual Volume 3 at all Riderdistributors. Also announced as avail-able for Jan. 1950, is Manual No. 20.

8RADIO SERVICE DEALER DECEMBER, 1949

"The Professional Radioman's Magazine"-

published monthly. All articles are exclusive

and timely. Practically every issue is worth

what an entire I year subscription costs.

Service DealersForm A Group,

Subscribe to "RSD"-

SAVE Up to $1.00 each.

* The more in a group the bigger the savings.6 men in a group save $1.00 each; 4 men groupssave $ .75 per man. Present "RSD" subscribersmay participate in or form a group with co-workers, or even competitors. Still active sub-scriptions are automatically extended I year.

Start a Group today! The timely and exclusivetechnical data appearing in future ssues of

"RSD" will make this the best investment youever made. The special Group Rate offer maybe withdrawn at any time-so hurry.

Use This Coupon For Convenience(The coupon below can be used for from I to 6 subscription orders. Use it today!)

TEAR OUT ® MAIL TODAY!

RADIO SERVICE -DEALER MAGAZINE342 Madison Ave., New York 17, N. Y.

Please enter I year subscription orders for the namesgiven below. Our remittance is enclosed.

NOTE: If you do not wish to tear this order blank out, just print ortype the information on a single sheet of paper, following the stylegiven. Each subscriber's occupation must be clearly described.

NameAddress

Describe Title or Position and Type of Business..

State whether a New Subscriber or Renewal Order

NameAddress

Describe Title or Position and Type of Business


NameAddress

Describe Title or Position and Type of Business.........


One I -year subscription Two I -year subscriptions, each Three I -year subscriptions, "

In U.S.A.& Canada

$2.001.75.50

ForeignRates$3.00

2.752.50

Four I -year subscriptions, .25 2.25 Five 1 -year subscriptions, .10 2.00 Six I -year subscriptions, .00 1.50

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"We don't propose to let even one customer walk out of ourplace. If it's a TV, AM or FM set that needs servicing, we'remaking sure that we can handle the job satisfactorily. Andone way of making sure is by constantly using our referencelibrary of Rider Manuals."-Says Mr. I. ZwickelSignal Radio HospitalBrooklyn, New York

For Greater Efficiency...For More Information...For More Value For Your MoneyPlace Your Order Now for the NEW RIDER Tlf MANUAL voL3

Larger Page Size! 12" x 15"! All Pages in Place!

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New RIDER MANUALVOL. XX

New Material! More Material!

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tage of text and double spreads assembled in

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A very clever Rider DisplayIdea, 14 x 17 inches,

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NOTE: Are you receiving your copy of "Successful

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to every Serviceman.Write for it . . it's FREE!

Here is accurate, authentic, reliable servicinginformation direct from 74 TV receiver manu-facturers. New, enlarged page size, 12 x 15inches, with all pages filed in position. Giantpages have been retained... but now haveonly one fold for greater convenience anddurability. There's more ease in using, too,because there are fewer pages to turn andbecause diagrams and related text are moreclosely positioned. Order now from your jobber.

Equivalent of Approximately 2032Pages (81/2 x II"), Plus Cumula-tive Index Volumes I, 2 and 3, Plusthe Famous "How It Works" Book

Complete

Volume VIAbridged Manuals I to V

(one volume) $19.80Record Changers and Recorders $ 9.00Master Index, Covering Manuals,

Vols. I to XV $ 1.50PA Equipment Manual, Vol. I $18.00

11"RIDER MANUALS

Television Manual Volume 3 (Plus"How It Works" Book and Index) $21.00Television Manual Volume 2 (Plus"How It Works" Book and Index) $18.00Television Manual Volume 1 (Plus"How It Works" Book and Index) $18.00Volume XIX $19.80Volume XVII I $19.80Volume XVI I $16.50Volume XVI $ 8.40Volume XV $19.80Volume XIV to VII (each volume) $16.50

$12.50

JOHN F. RIDER PUBLISHER, Inc., 480 Canal Street, New York 13, N. Y. Export Agent: Rocke

R DER

Easier to Use!

FM TRANSMISSIONand

RECEPTIONby John F. Rider and Seymour

D. UslanA "must" book for the radio servicemanwh

looks to FM and televisionan

nt portof his future earnings.

Covers alltypesPolice,ta of fre-

oquency modulationystems employed

in TV,

radio, amateurradio, railroad,

aviation, marine,police, point-to-oint

and mobile re-ceivers

416 Pages, Profuselyillustrated. ;360

TV PICTUREPROJECTION

andENLARGEMENTby Allan LytelTimely .. Compiefe .. AuthoritativeCombines

theory with practice,and offers a clear

and wellorganizedexplanation

of the fundamentots of light, optics and optical

systemsas

employedin home television

receivers,with eras

n projectiontypes and front lens enlarge

-

charts

*

ment. 192Pages; 119 illustrations,

BUSINESSHELPERby Leslie C. Rucker (Rucker

Radio Wholesalers)Written by a successfulbusiness

man who startedfrom scratch

and workedhis way up to a chain of

3 stores.Any one of his many worthwhile

ideascan mean fifty times

the cost of this bookie 'leasin Your pocket. 144pages; 22 chapters.,

Corp., 13 E. 40th St., N.Y.C., Cable, ARLAB.MANUALS koteapt SUCCESSFUL:RVICING

NOTE: The Mallory TV Service Encyclopedia, 1st TV Edition, makes reference to only one source of TV receiver schematics-Rider TV Manuals.NOTE: The Mallory Radio Service Encyclopedia, 6th Edition, makes reference to only one source of radio receiver schematics-Rider Manuals.NOTE: The C -D Capacitor Manual for Radio Servicing, 1948 Edition No. 4, makes reference to only one source of receiver schematics-Rider Manuals.10RADIO SERVICE DEALER DECEMBER, 1949

International

5R/wiring

SOUND F STAGESin U and 3911 dikaivithil

OF great importance in the servic-ing of television and frequency

modulation i-f stages is considerationof loss factors. Failure to observe cer-tain precautions will invariably resultin a weak signal-particularly in thehigher frequency range of the receiver.This, of course, applies to the r -f, mix-er and oscillator stages as well as thei-f stages, for in all high frequencycircuits the manufacturer takes nu-merous precautions to keep lossesdown. Such losses vary, and includethose due to stray capacitance toground, lead inductance, inter -elec-trode capacity, insulation losses andskin effect. Coils and capacitors aremounted on forms which are knownto have low loss for high frequencies,and such materials include Isolantite,Polyethelene, Lucite, Plexiglass andother high frequency insulators.

Tubes are chosen which have lowinter -electrode capacity so that theshunting effect of such capacity willbe small. Wiring is kept away fromground and adjacent leads so thatthe capacity formed between two suchsections will not provide a low react-ance path for the signal energy. Hook-up wire between parts is kept as shortas possible so that it will not act asan inductance for the very high fre-quencies and thus behave as a chokeinstead of a conductor. Skin effect,the tendency of high frequency cur-rents to flow on the outside (skin) ofthe wire, is minimized by using largediameter wire in coils and other con-ductors of signal energy.

The technician must take the sameprecautions detailed above when serv-icing TV and FM receivers so thathe will not unknowingly undo themanufacturer's high frequency designconstruction. When any capacitor, re-sistor or coil is found defective caremust be taken that the leads on such

by MATTHEW MANDLTechnical Institute, Temple University

Servicing high frequency i-f stages requires an under-standing of the behavior of high frequency components andconstruction. In this article the author deals with practicalservice problems relating to h - f sound i -f circuits.

Fig. I. Sound pick -off in R. C. A.81241-81242 TV receivers.

new units are as short as the oneswhich were on the original compo-nents. Lead dress must also be ob-served carefully, for bunching wiretoo closely together during servicing,or running them along the chassis,will contribute seriously to losses andwill decrease the receiver gain farbelow than what it should be.

I -F Input Methods

In regular FM receivers, the coupl-ing between mixer and i-f stage isconventional, but in the FM (sound)section of television receivers, various


methods will be encountered. Onepopular method is that shown in Fig.1. used by RCA in their 8T241 -8T242,etc. series of receivers. Here, thesound is picked off a transformer ar-rangement between the 2nd pix i-fstage and the 3rd pix i.f. The circuitis a transformer for the sound only,because the picture i.f. is coupled tothe 3rd i-f stage through a seriescoupling capacitor. The primary ofthis transformer is resonant to oneof several frequencies used for thestagger -tuned picture i-f system. Thesecondary has two functions-one isto trap the sound out of the picturei-f stages so that it will not put soundbars on the picture tube face-andthe other function is to act as a pick-up coil for the sound i-f. (21.25) whichis then applied to the grid of the 1stsound i-f stage.

Other receivers, including Emerson,Admiral, DeWald, etc. use a similarsystem though some take the soundafter the 1st picture i.f. instead of thesecond. When the inter -carrier systemis used, sound i-f is procured from the2nd video detector, and sometimesfrom the output of the 1st video am-plifier. The two signals, video andsound, are mixed in the detector toproduce 4.5 me for the i.f. of thesound stages.

Other variations of input to thesound i.f. will, of course, be encoun-tered, and the receiver schematicshould be consulted when in doubtduring trouble -shooting. Some useseries traps instead of the type trapshown in Fig. 1. Figure 2 indicates

II

the method employed in Zenith tele-vision receivers.

The sound i.f. frequency as pro-duced in the output of the mixer is21.3 mc for the Zenith models usingChassis 28F20. This signal is coupledto the 1st sound i.f. by utilizing aseries tuned trap. As with all seriestuned circuits, the impedance is lowat the resonant frequency and maxi-mum current flows. This means, ofcourse, that this series circuit willpass a maximum signal current forthe frequency to which it is tuned -21.3 mc in this case.

Inasmuch as a series circuit presentsa high impedance to frequencies aboveor below resonance, this series circuitin the Zenith thus traps out the pic-ture frequencies. The small inductanceshown in Fig. 2 between points marked2 and 5 of T2 provides common coupl-ing between the L15 series resonanttrap and the sound input coil at thegrid.

FM I -F StagesThe intermediate frequency stages

of an FM receiver or the sound por-tion of a television set, must havewide band characteristics in order topass the necessary carrier and side -band components present during mod-ulation. In standard FM each stationis allocated a 200 kc bandwidth, ofwhich 75 kc each side of the carrierrepresents maximum carrier swing.An ideal response curve in the i-famplifiers would be as pictured at Ain Fig. 8. Here the response curvewould have steep, vertical sides, andhave a uniform flat top. Such an ideal,however, is virtually impossible toachieve in our receivers and compro-mise measures must be resorted to. Anordinary response curve, such as atB gives good gain, but has too sharpa peak to be generally useful. Thecurve shown at C more nearly ap-proaches the type generally found intypical receivers and this is the com-promise referred to.

Over -coupling will broaden the re-sponse of an amplifier stage, but will,of course, also reduce gain since the

Q of the circuit if affected. Loadingdown a tuned circuit with resistancewill also lower the Q and increaseband -width. The curve shown at C,while not fiat over the entire 200 kcrange, does, nevertheless, give im-proved gain and better adjacent chan-nel selectivity and represents the band-pass usually encountered.

In the television sound i-f stages,wide bands are again employed, andin this instance a band-pass as largeas that in standard FM is used so thatthe sound i.f. does not drift out ofrange when the local oscillator drifts.A 50 kc band-pass would normally beadequate, and would bring in all thesound information necessary. Since,however, present-day oscillators of tel-evision receivers are prone to drift,the sound i.f. bandpass is made 200

z-A-

-B- z.t(.0

-C-

-100 KC. +100 KC

-100 KC. +100 KC

1

0 +100 KC.

Fig. 3. Ideal, ordinary and preferredi-f response curves.

or more kc wide, so that the 50 kcspread of the FM signal would havesufficient room to drift without lossof sound. Picture drift is not ascritical because of the 4 mc band-pass in the picture i.f. stages. A 50 kcdrift in the sound would be serious,

Fig. 2. Sound pick -off in Zenith 28F20 TV receivers.

Fig. 4. A typical combination AF andFM i-f arrangement.

while a 50 kc drift in a 4 me band-pass (4,000 kc) would be relativelysmall.

Double -Tuned I -F StagesWhen standard FM (88-108 mc)

is used in radio receivers which alsoincorporate AM, the arrangement asshown in Fig. 4 is often used. Boththe FM coils (10.7 mc) and the AMcoils (455 kc) are enclosed in the samei-f shield. Powdered metal core slugsare utilized to tune individually thevarious transformer primaries andsecondaries. Separate coil forms maybe used for the FM and AM, or bothmay be wound on the same form. Ineither case, the FM coils are so ar-ranged that the leads from them gointo the tube terminals first.

When the set is turned on the FMband, and a 10.7 mc i.f. appears inthese circuits, it will find a resonantfrequency in the top coils shown inthe figure. A parallel resonant circuitis present which offers a high im-pedance and thus develops a largesignal voltage for the desired frequen-cy (10.7 mc).

During this time the coils whichare tuned to 455 kc are not at reso-nance, and for this reason present alow impedance to the 10.7 me fre-quency present in these circuits. Thus,they appear as a short circuit tothe 10.7 me signal.

During the time the receiver is setfor AM, and a 455 kc signal appearsin the amplifier circuits, the lowercoils are at parallel resonance andpresent a high impedance to the 455kc signal. This means, then, that therewill appear a large signal voltageacross these coils. The 10.7 me coils,not encountering a resonant frequen-cy, will offer a low impedance and willact as a short circuit to the- 155 kcsignals. In this fashion each coil is

[Continued on page 30]


MODERNELECTRONIC VOM

by ALLAN LYTEL

Author of TV Projection and Enlargement

Describing the design, operation, and applications of a modern electronic VOM

OLTAGE and resistance meas-urements play an important part

in the servicing technique of any wellequipped radio and television repairshop. As far as voltage is concerned,there are many points in televisionand radio circuits where electronicvacuum tube voltmeters alone canprovide reliable readings. One of thesepoints of special interest is the gridleak of an oscillator. The voltage read-ing measured on the d -c scale obtainedacross the grid leak resistor is an im-portant indication of the operatingcondition of an oscillator. However,voltmeters with insufficient input re-sistance on the voltage scale, cancause a severe enough loading effectto make the oscillator inoperative.Furthermore, it is essential that themeasuring instrument place no load,resistive or capacitive, upon the cir-cuit to be measured, otherwise thenormal operation of the circuit willbe impeded by the measuring device,and an inaccurate reading will be ob-tained.

The testing of an audio couplingcapacitor is an example of where theelectronic meter is needed for its ex-tremely high resistance scale. Becausethe grid resistor used in an audioamplifier stage is usually of a highvalue, severe distortion will be pro-duced by a leaky coupling capacitorhaving a shunt resistance of manymegohms. Only a high resistance ohm-meter can be used to measure theshunt resistance of this coupling ca-pacitor with any degree of accuracy.

These electronic meters do not al-ways have their full capabilities rea-lized by the servicemen. The modelillustrated (RCA WV75-A Voltohm-ist) is an example of modern up -to -

WASHER

HEX NUT

6 AL5DIODE

RESISTOR

RING

CAP

BAKELITECOVER

PROBE BODY(REAR HALF)

ILL-BUSHING

BUSHING

DIODEWr-SOCKET

CAPACITOR

PROBE BODY(FRONT HALF)

924J,=7 12 0

date design in a meter. Among itsfeatures, is a Zero -Center Readingscale which is useful in aligning dis-criminators whose output may beeither plus or minus, depending uponthe frequency input during alignment.

R.M.S. vs. Peak -To -Peak Values

This meter will measure d -c volt-ages from 0.3 to 1000, a -c voltagesfrom 0.3 r.m.s. to 1000 r.m.s. andresistance measurements from 0.1ohms to 1000 megohms. The r -m -s.(Root Mean Square) values aregiven for sine wave voltages whichis an indication of 0.345 of the actualpeak -to -peak value on which the read-ing is based. Complex waves or pulsesmay also be measured in terms of

Exploded view of special diodeprobe which is used in conjunc-tion with electronic VOM to meas-

ure r -f and a -f voltages.

peak -to -peak values, where r-iu-s read-.ings do not convey useful information.In order to convert from r -m -s volt-ages to peak -to -peak voltages the chartshown in Fig. 1 is quite helpful. Bymeans of this conversion chart, thescale reading which is in r.m.s. voltsmay be changed into peak -to -peakreadings without any calculations.Using this chart, the actual peak -to-peak value of pulses may be founddirectly. Figure 2 illustrate the rela-tionship between the r -m -s and peak -to -peak value of a sine wave, as wellas a comparison of other waveformsthat may be encountered. This repre-sents one of the ramifications of theuse of a vacuum tube voltmeter. This


the method employed in Zenith tele-vision receivers.

The sound i.f. frequency as pro-duced in the output of the mixer is21.3 mc for the Zenith models usingChassis 28F20. This signal is coupledto the 1st sound i.f. by utilizing aseries tuned trap. As with all seriestuned circuits, the impedance is lowat the resonant frequency and maxi-mum current flows. This means, ofcourse, that this series circuit willpass a maximum signal current forthe frequency to which it is tuned -21.3 mc in this case.

Inasmuch as a series circuit presentsa high impedance to frequencies aboveor below resonance, this series circuitin the Zenith thus traps out the pic-ture frequencies. The small inductanceshown in Fig. 2 between points marked2 and 5 of T2 provides common coupl-ing between the L15 series resonanttrap and the sound input coil at thegrid.

FM I -F StagesThe intermediate frequency stages

of an FM receiver or the sound por-tion of a television set, must havewide band characteristics in order topass the necessary carrier and side -band components present during mod-ulation. In standard FM each stationis allocated a 200 kc bandwidth, ofwhich 75 kc each side of the carrierrepresents maximum carrier swing.An ideal response curve in the i-famplifiers would be as pictured at Ain Fig. 3. Here the response curvewould have steep, vertical sides, andhave a uniform flat top. Such an ideal,however, is virtually impossible toachieve in our receivers and compro-mise measures must be resorted to. Anordinary response curve, such as atB gives good gain, but has too sharpa peak to be generally useful. Thecurve shown at C more nearly ap-proaches the type generally found intypical receivers and this is the com-promise referred to.

Over -coupling will broaden the re-sponse of an amplifier stage, but will,of course, also reduce gain since the

Q of the circuit if affected. Loadingdown a tuned circuit with resistancewill also lower the Q and increaseband -width. The curve shown at C,while not flat over the entire 200 kcrange, does, nevertheless, give im-proved gain and better adjacent chan-nel selectivity and represents the band-pass usually encountered.

In the television sound i-f stages,wide bands are again employed, andin this instance a band-pass as largeas that in standard FM is used so thatthe sound i.f. does not drift out ofrange when the local oscillator drifts.A 50 kc band-pass would normally beadequate, and would bring in all thesound information necessary. Since,however, present-day oscillators of tel-evision receivers are prone to drift,the sound i.f. bandpass is made 200

z-A- :Ec

-B- 7.1

-C- z0

L

-100 KC +100 KC

-100 KC +100 KC

-100 KC. 0 +100 KC.

Fig. 3. Ideal, ordinary and preferredi-f response curves.

or more kc wide, so that the 50 kcspread of the FM signal would havesufficient room to drift without lossof sound. Picture drift is not ascritical because of the 4 mc band-pass in the picture i.f. stages. A 50 kcdrift in the sound would be serious,

Fig. 2. Sound pick -off in Zenith 28F20 TV receivers.

Fig. 4. A typical combination AF andFM i-f arrangement.

while a 50 kc drift in a 4 mc band-pass (4,000 kc) would be relativelysmall.

Double -Tuned I -F StagesWhen standard FM (88-108 mc)

is used in radio receivers which alsoincorporate AM, the arrangement asshown in Fig. 4 is often used. Boththe FM coils (10.7 mc) and the AMcoils (455 kc) are enclosed in the samei-f shield. Powdered metal core slugsare utilized to tune individually thevarious transformer primaries andsecondaries. Separate coil forms maybe used for the FM and AM, or bothmay be wound on the same form. Ineither case, the FM coils are so ar-ranged that the leads from them gointo the tube terminals first.

When the set is turned on the FMband, and a 10.7 mc i.f. appears inthese circuits, it will find a resonantfrequency in the top coils shown inthe figure. A parallel resonant circuitis present which offers a high im-pedance and thus develops a largesignal voltage for the desired frequen-cy (10.7 mc).

During this time the coils whichare tuned to 455 kc are not at reso-nance, and for this reason present alow impedance to the 10.7 mc fre-quency present in these circuits. Thus,they appear as a short circuit tothe 10.7 mc signal.

During the time the receiver is setfor AM, and a 455 kc signal appearsin the amplifier circuits, the lowercoils are at parallel resonance andpresent a high impedance to the 455ke signal. This means, then, that therewill appear a large signal voltageacross these coils. The 10.7 mc coils,not encountering a resonant frequen-cy, will offer a low impedance and willact as a short circuit to the- 155 kcsignals. In this fashion each coil is



MODERNELECTRONIC VOM

by ALLAN LYTEL

Author of TV Projection and Enlargement

Describing the design, operation, and applications of a modern electronic VOM

OLTAGE and resistance meas-urements play an important part

in the servicing technique of any wellequipped radio and television repairshop. As far as voltage is concerned,there are many points in televisionand radio circuits where electronicvacuum tube voltmeters alone canprovide reliable readings. One of thesepoints of special interest is the gridleak of an oscillator. The voltage read-ing measured on the d -c scale obtainedacross the grid leak resistor is an im-portant indication of the operatingcondition of an oscillator. However,voltmeters with insufficient input re-sistance on the voltage scale, cancause a severe enough loading effectto make the oscillator inoperative.Furthermore, it is essential that themeasuring instrument place no load,resistive or capacitive, upon the cir-cuit to be measured, otherwise thenormal operation of the circuit willbe impeded by the measuring device,and an inaccurate reading will be ob-tained.

The testing of an audio couplingcapacitor is an example of where theelectronic meter is needed for its ex-tremely high resistance scale. Becausethe grid resistor used in an audioamplifier stage is usually of a highvalue, severe distortion will be pro-duced by a leaky coupling capacitorhaving a shunt resistance of manymegohms. Only a high resistance ohm-meter can be used to measure theshunt resistance of this coupling ca-pacitor with any degree of accuracy.

These electronic meters do not al-ways have their full capabilities rea-lized by the servicemen. The modelillustrated (RCA WV75-A Voltohm-ist) is an example of modern up -to -

WASHER

HEX NUT

6AL5DIODE

RESISTOR

RING

BAKELITECOVER

PROBE BODY(REAR HALF)

BUSHING

BUSHING

DIODESOCKET

CAPACITOR

PROBE BODY(FRONT HALF)

92C -7120

date design in a meter. Among itsfeatures, is a Zero -Center Readingscale which is useful in aligning dis-criminators whose output may beeither plus or minus, depending uponthe frequency input during alignment.

R.M.S. vs. Peak -To -Peak ValuesThis meter will measure d -c volt-

ages from 0.3 to 1000, a -c voltagesfrom 0.3 r.m.s. to 1000 r.m.s. andresistance measurements from 0.1ohms to 1000 megohms. The r -m -s.(Root Mean Square) values aregiven for sine wave voltages whichis an indication of 0.345 of the actualpeak -to -peak value on which the read-ing is based. Complex waves or pulsesmay also be measured in terms of

Exploded view of special diodeprobe which is used in conjunc-tion with electronic VOM to meas-

ure r -f and a -f voltages.

peak -to -peak values, where r -m -sings do not convey useful information.In order to convert from r -m -s volt-ages to peak -to -peak voltages the chartshown in Fig. 1 is quite helpful. Bymeans of this conversion chart, thescale reading which is in r.m.s. voltsmay be changed into peak -to -peakreadings without any calculations.Using this chart, the actual peak -to -peak value of pulses may be founddirectly. Figure 2 illustrate the rela-tionship between the r -m -s and peak -to -peak value of a sine wave, as wellas a comparison of other waveformsthat may be encountered. This repre-sents one of the ramifications of theuse of a vacuum tube voltmeter. This.


technique is becoming increasinglyimportant in television servicing andrepair.

Circuit Operation

The measuring circuit (see Fig. 3)of this electronic voltmeter uses 26K6 GT tubes in a balanced bridgecircuit providing a very high degreeof stability and input impedance. Asseen in the schematic, resistor R-29(39K) is a cathode resistor which iscommon to the two circuits. Depend-ing upon the function the control gridof one tube is at a fixed potentialwhile the voltage to be measured isplaced upon the grid of the other tube.The varying potential applied to thefirst grid will cause a change of theplate current of the first tube; sincethe grid of the other tube is at a fixedpotential, the plate current of the firsttube will cause an opposite effect onthe grid of the second tube. Thus,there will be an unbalance betweenthe plate circuits of the two tubes. Achanging plate voltage in V-/ willcause the opposite change in platevoltage in V-2 because of the commoncathode resistor. This unbalance isread on the 200 microampere metermovement and the scale is calibratedto read either volts or ohms.

A 6AL5 tube is used as a full -waverectifier in the diode probe and thecontact potential of this tube is bal-anced out against a similar 6AL5tube located in the meter case. In thismanner the zero scale setting is un-changed when the range switch ischanged from one position to another.

As a d -c voltmeter, there are ranges1,000. The input resistance is 11 meg-

40EtTIO

BLACK LEAD `R

.3,

OPT

1* -v*HE tiIER0 CENTER

OWLSAC

OOP( PROBE

EC

POO

- 1 ENTER

L/r a..Ar

RMS(RED SCALE) 0 0.3 0.6 0.9 12 1.5 1.8 2.1 2.4 2.7 3.0

PK-PK 111%S*Wet1(100)%*11,11q??1,11%S\'M .1r?(Olillk 113-V RANGE 0 0.9 1.8 . 23 3.6 4.5 5.4 6.3 7.2 8.1

PK-PK 010-V RANGE

RMS 0(RED SCALE)

RMS(BLACK SCALE) 0

PK-PK30-V RANGE 0

PK-PK300-V RANGE 0

12 .15 18 21 24 27

0.3 0.6 0.9

10

12 1.5 1.8 2.1 2.4 2.7 3.0

9 18 27 36 45 54 63 72 81

PK-PK 01000-V RANGE I

PK-PK 0100-V RANGE L.

I I I I I II1 I, 1 I '90 180 270

300 600

30 60

360 450itiiiI I, 1.1

540 630 720 810

900 1200 1500 1800 2100 2400

90 120 150

2700

180 210 240 270RMS 0

(BLACK SCALE) 9 10

92CM-7121Fig. I. Conversion chart for r -m -s to peak -to -peak voltages.

from zero to 3, 10, 30, 100, 300, andohms on all ranges, which amountsto 3.7 megohms per volt on the 3 voltrange. As an a -c voltmeter, there areranges from 0 to 3, 10, 30, and 100,r.m.s. volts directly to the diode probe.

E -ITVPLAT TO I LT

PEAR

.TERVOTJ

WASINE

VESOVA.RE C01.11,LITWAVE T -.LSE WAVE

----- READI. PROPORTIONAL TO CAR TO- TEAK VOLTAGE AT PROBENETER SCALE. CALIBRATED IN RAO VALVE OP A 3INE

spo-NAT

Fig. 2. Relationship between r -m -s val-ue and peak -to -peak values of a sinewave. Note values of other waves.

An audio frequency multiplier isavailable which has an attenuationratio of 10 to 1. This provides 2 scales,0 to 300 and 0 to 1000 r.m.s. volts upto a frequency of 15 kc.

The frequency response when thediode probe is used directly is from

e.SEREAVDRIvETT ADJUSTMENT4 L.NATTAGRO ARROW INDICATES CLOCToret ROTATION

Fig. 3. Circuit diagram of R.C.A. WV75-A VoltOhmyst.

*SCA -1.23

30 cps to 250 mc. When the diodeprobe is used with the leads supplied,the frequency response drops to 30cps to 30 mc and with the diode probeand audio frequency multiplier, thefrequency response is 30 cps to 15 kc.See Fig. 4 for values of effective inputresistance and capacitance of diodeprobe versus frequency.

Operation

The electronic voltmeter is set inoperation by plugging in the powercord and using the Zero Adjustmentto bring the pointer to zero. The se-lector Switch is thrown to plus voltsand the zero adjust is rotated to ob-tain zero reading. Selector Switch isthen thrown to Ohms and Ohms Ad-just is used to bring the meter to thelast line on the ohm scale. When meas-uring d -c volts, the meter is used aswith any voltmeter except for the factthat there are two positions on theselector switch which may be used;one is for positive volts and the otherfor negative volts. This allows thetest leads to stay in position evenif the polarity of the voltage changes.The ground lead should be kept atchassis potential whenever possible.If the selector switch is thrown toZero Center position the needle willmove to the center of the scale. Thisis convenient for special applicationssuch as discriminator voltage align-ment for FM and TV receivers. Asmay be seen from the scale of themeter, the zero center position will notgive true scale indication unless it isused with care. As an example on' a 10volt range, zero center isl located at 5volts. A reading of 8 volts is an in-dication of 3 volts positive while areading of 2 volts is an indication of3 volts negative.

The special diode probe is used tomeasure a.c. which may be either

[Continued on pake 29]


Savicing

PHOTO -ELECTRICequiPmf2n-t

One or two comments seem appro-priate before leaving the subject ofadjustment. While we are likely to re-gard the type of equipment underdiscussion as an "on -off" device,this is not strictly true. The openingor closing of the relay contacts de-pends not merely on the absence orpresence of light at the phototube,but rather on the change in the totalamount of light reaching it. Extrane-ous light must, therefore, be takeninto account, and very often adjust-ments must be made with a consider-able amount of light reaching thetube from a source other than thatof the actuating lamp. Under suchconditions some trial and error ad-justment must be made before thedesired operation is obtained. Anotherimportant factor is the current re-quired to close the relay contactscompared with that necessary to holdit in operation once it is energized.As an illustration, suppose we assumethat a given relay takes 15 milliam-peres for full closure of its contacts,but once closed they will remain closedwith only 10 milliamperes flowingthrough the coil. If we were now toadjust the sensitivity control so thatthe amplifier plate current at fullillumination and at zero illuminationvaried between 12 and 20 milliam-peres, we would find that we will notobtain correct operation; the 20 mil-liampere current at full illuminationof the phototube is ample to energizethe relay, but when the light is cutoff the plate current drops to 12milliamperes (more than enough tohold the relay in operation once en-ergized) and the relay will not dropout properly.

by WILLIAM R. WELLMA1

PART 2

Final installment of this article began in the October R.S.D.Further servicing techniques, special types discussed..

CORE --

COILTERMINAL

COIL"'

FRAME

----ARMATURE

PIVOT

k NORMALLYOPEN

CONTACTS

NORMALLYCLOSED

CONTACTS

Fig. 4. Typical relay used in photo-electric apparatus.

Conditions Causing Lack of Sensitivity

By lack of sensitivity we mean acondition in which the, relay will notoperate properly with normal illumi-nation and darkening of the photo -tube, and in which no setting of thecontrol accomplishes 'the desired re-sults. It is one of the more commoncomplaints associated with this typeof apparatus, and may arise from avariety of causes. If you encountertrouble of this nature, it is suggestedthat you go over the material con-tained in the preceding section.

A listing of some of the causes ofpoor sensitivity would include thefollowing: defective phototube or am-plifier tube, defective lamp or improp-er focusing, damaged or improperlyadjusted relay, serious changes in

plate or screen voltages, and possiblya change in the value of the grid re-sistor, although this is not too likely.

Suppose we take up the possibledefects listed above. Many units usea standard automobile lamp as alight source. The filament of sucha lamp affords a concentrated spotor strip of light. It is important thatwhen replacement is made the correcttype of lamp be installed. It has beennoted that in some types the maker'strademark or monogram on the bulbhas a tendency to interfere with cor-rect focusing at the distances com-monly used in photoelectric work. Ofcourse, it is understood that both thelamp and the lens must be clean; thiscan best be done with an alcohol swab.followed by polishing with lens tissue.Incidentally, the new silicone -im-pregnated tissues are excellent forthis purpose. Proper focusing hasalready been taken up as well as thematter of the distance between thelamp and the phototube.

The majority of commerciallybuilt units are so designed that thetubes are operated at very conserva-tive voltages and therefore their lifeis lengthened, but failure is a dis-tinct possibility and cannot be over-looked. Replacement of amplifiertubes is a routine matter since inmost cases they are standard radiotypes. Of course, the number of pho-totube types made is far smaller thanin the case of general purpose tubes,yet it is a good idea to keep at handa copy of the RCA bulletin describing


such tubes; Westinghouse and Gen-eral Electric publish similar material.

Concerning the electrode voltagesappljed to the tubes, it should be notedthat it is common practice to use nohigher than 90 to 100 volts on theplate of a gas type phototube, andnot more than 250 on the plate of ahigh vacuum type. Remember that inmeasuring the electrode voltages oftubes used in a -c operated equipmentan a -c voltmeter range must be used.

Since relays are not used to anygreat extent in ordinary radio equip-ment, a few words concerning theoperation and adjustment of thesecomponents may be appropriate. Fig-ure 4 shows a relay of the type com-mon to photoelectric apparatus. Ex-cept in cases where a thyratron tubeis used, the coil resistance of suchrelays is likely to be somewhere be-tween 2,000 and 10,000 ohms. Con-tact arrangements vary between asimple pair of normally open contacts(meaning that the contacts are openwhen the relay is not energized) andfour, six or even more contacts, de-pending upon the work that the deviceis expected to do. Very often thereis a combination of normally openand normally closed contacts. As canbe seen from the illustration, the ten-sion or force which holds the arma-ture in a normal position is suppliedby the contacts themselves. Damageto the contacts due to rough handlingor other cause might possibly changethe amount of current needed to makeor break the contacts. Adjustmentshould never be attempted unless it isdefinitely known that the relay isout of order, and then only with thegreatest of care. A piece of steelabout 1/8 inch wide and having aslot in the end which is slightly widerthan the thickness of the contact

Ry1

Ry

Rya

TO EXTERNALCIRCUIT

Fig. 5. System of safeguarding work-er against machine failure using three

separate relays.

spring is the best type of tool to use,although adjustments might be madewith a pair of long nose pliers. Youwill notice that the armature carriesa projecting tongue or lever whichbears against the movable contact.Bending the moving contact towardthe armature lever will increase thetension and thus more current willbe needed to fully close the contacts.On the other hand, bending the con-tact in the opposite direction willhave the effect of making the relaymore sensitive. All bending shouldbe done at the upper end of thespring; that is, at the end oppositethe contact. Adjusting contact springsis a rather delicate operation. At notime should the bending be sufficientto produce a kink or visible bend inthe spring. Relay adjustment shouldbe attempted only in emergencies, forunless data is available concerningthe operating current of the relay,and unless means is at hand for meas-uring and controlling the currentwhile adjustments are made, it islikely to be largely guess work.

Causes of Non -operation of Unit

Very often the complete failure ofa unit may be traced to causes whichare the same as those listed above. Itis quite obvious that a defective pho-totube or amplifier tube, an improp-erly adjusted relay, reduced electrodevoltages or a complete lack of voltages,a light source which is too far awayor not properly focused on the photo -tube, are each capable of preventingthe unit from functioning. Then,there are the usual power supply fail-ures common to all electronic equip-ment, such as a defective transformer,rectifier tube or filter condenser.Shorting of the condenser C connectedacross the relay coil or an open wind-ing will, of course, prevent the relayfrom operating. Many failures may betraced to tarnished, pitted or burnedrelay contacts; the latter two causesare especially likely in cases where thecontacts open and close circuits car-rying considerable current. Cleaningcontacts is best done with crocuscloth. It should be noted that read-justment is sometimes necessary aftercleaning.

In line with modern methods oftrouble isolation and diagnosis, a verysimple procedure for localizing troublemay be used. This is the measure-ment of the voltage change acrossthe grid resistor, R. Of course, sincethe resistor is usually very high, theuse of a high resistance voltmeter (avacuum tube voltmeter, preferably)

Fig. 6. Typical smoke detector.

is mandatory. Connect the meteracross the resistor and note the volt-age with the lamp turned on; thenturn the lamp off or cover the photo -tube and observe the new reading.The difference between the two isa measure of the current developed bythe phototube. If the voltage changeis great enough to vary the amplifierplate current over wide enough limitsto result in opening and closing ofthe relay contacts under normal cir-cumstances, the trouble then lies inthe amplifier or the relay. On theother hand, if the voltage changeseems too small, the light source, thephototube or possibly the resistor it-self is at fault.

Before leaving the subject of troublelocation, mention should be made of acommon defect which does not fit intoeither of the classifications just dis-cussed. This is chattering or buzzingof the relay; and is most likely tooccur in equipment using an a -cthe relay coil, and will be found tobe caused by opening of the condenserC connected in parallel with the coil.

Special Types of PhotoelectricEquipment

Many types of phototube apparatusdiffer materially from those alreadydescribed. First of all, there are sometypes in which the amplifier does notterminate in a relay. In equipmentused for measurement and compari-son purposes, some type of currentmeasuring instrument is used instead,and this instrument will be calibratedin appropriate units. One such deviceis used for matching and comparingthe colors of such materials as tex-tiles, paints, paper, dyes, etc. In use,a calibrated potentiometer is adjusteduntil the light reflected from thestandard sample gives a predeterminedreading on the meter scale. Thesample to be compare';is then insertedand the potentiometer readjusted un-

[Continued'on page 28]


TV TRUCKSoivs2.4 gnAtattation Otabfizmit

THE problems were how to savetime, money and labor in televi-

sion servicing. The firm concernedwith the solutions is the L & S RadioSales Company, 132-134 North Street,Middletown, New York. Merchandis-ing was actually being retarded be-cause customers and potential buyerscould not be given the right amountof attenion at regular convenient pe-riods for themselves and for L & S.

Mr. Earl Lounsbury and Mr. DaveShohet, the two partners of the com-pany, began to think that televisionselling was going to become some-what of a burden. They had twelveyears radio experience behind them.Today they can look back at twoyears of television business. Withdemands coming to them steadilythey saw, not long ago, that someimprovement in servicing was nec-essary at once.

Solution of Problem"What we wanted was accurate

engineered television installation,"Mr. Lounsbury explained. "It seemssimple now but before we hit uponthe right answer we spent many anx-ious months trying to figure out whatwas then a very tough problem. Thesolution came with a special onehalf ton panel Ford truck. It isrigged with two ladders. One is al-uminum. The other is wood. Theyare both double sectioned. Whenjointed the aluminum ladder reachesa height of 80 feet. The wooden lad-der goes as high as 60 feet. The truckis fully equipped with testing ap-paratus. We are now able to giveour customers not only complete sat-isfaction but constant rapid service."

The result is an increase in tele-vision business volume of twenty-fivepercent. Time and labor saving isestimated at fifty percent.

The L. L. Peters Company of Al-lentown, Pennsylvania, supplied thetowers. This cost was $450.00. Thetruck was bought for $2,200.00. Ithas paid for itself many times over,

by I. SIIYKE

how a Radio Service Dealer solved his problems of locatingthe most effective heights and locations of TV antennas infringe area installations, where these factors arc critical.

This attractive truck, and the adjustable extension ladder shown mounted onthe roof of the truck, has resulted in increased business, as well as quicker

and better installations.

Mr. Lounsbury said. The Ford isabout seventeen feet long and aboutseven feet wide. It is around sevenand one half feet high. The laddersrest on frames on either side ormiddle of the top of the truck. Ithas an all white enamel body withblack lettering with the company'sname, address and telephone number.The Fada emblem is on the door of themachine. Thus far it is the onlytruck of this type and used for tele-vision in the area. The L & S firmwas so enthusiastic about the port-able towers that it accepted agencysales for them. So far L & S hassold them in Poughkeepsie, Kingston,Newburgh, Monroe, Port Jervis, Mil-ford and other near -by cities andtowns.

Test panel RCA equipment in thetruck consists of a vacuum tube volt

meter, sweep generator, scope, cali-brator, tube tester and a regularsignal FM and AM generator.

"By having this new truck we arebusy daily with it," Mr. Lounsburywent on to say. "We continually arerevising new installations. Beforethis we had to throw up jobs hap-hazardly. It was all guess -work asto height. Now we can go to thevarious heights until we get theright picture."

The only local competition thatL & S could get with the new portabletower is from the Middletown FireDepartment's new hook and ladderwhich can attain a height of seventyfeet. Until the L & S tower the FireDepartment was the only one thatcould go that high. Of course usageof the hook and ladder as a television



CIRCUIT COURT

Philco Model 49-1606

The development of dry -disc typerectifiers in a number of current rat-ings and small size have made possiblethe design of instruments with spaceand weight saving qualities whichmust be very pleasing to the cabinetdesign groups. In addition, it islikely that cost factors may profitfrom the move. While most compactinstruments use the line voltage ap-plied directly to a single bank ofrectifier plates, ending up with somevalue of d.c. below 100 volts, it ispossible to achieve more nearly nor-mal operating voltages for the tubes.Increased performance from all anglescan then be obtained, in fact the com-parison with transformer operatedinstruments becomes favorable.

The instrument under discussion isa good example of the present trendin such design. A console radio-phonocombination, it has seven tubes, ofwhich three are multi -purpose, andoperates on both AM and FM broad-cast bands. A schematic of the powercircuits is shown and details of itsfunction may be of interest. Keep inmind that one side of the power lineis common to the returns of allcircuits within the set. This point isthe negative end of the d -c supplycircuit.

Beginning at the power plug, we findboth r -f and a -f by-pass capacitors.The pilot light operates from the fullline voltage, as does the phono motor.Then comes a protective resistor of50 ohms to limit the charging currentof the large filters. The first filtercondenser, a 40 g unit, is connectedso that it charges up on each halfcycle when the top plate of the firstrectifier stack is positive. A positivevoltage is thus developed at point A.An additional protective resistor isconnected in the negative side of therectifier.

The surges of voltage are alsorectified in the second rectifier andadd their potential to that developedat point A. The result is that at pointB we find a potential equal to some-thing like twice the line voltage. This

A a180 c

25

PLATE5005

180

+ 200 V.

40 40 SCREEN

T 5005+170 V.

40

40

2200

+150 V.ALL

OTHER8+

Partial schematic of

voltage is stored in the second 40 /Ifcapacitor. Filtering begins at thispoint and the first section has 180ohms and another 40 Af. Potential forthe plate of the 5006 output tube istaken off at this point. The value is200 volts.

Another section of 180 ohms and40 Af drops the voltage to 170 for theoutput tube screen and further re-duces hum. The remainder of thetubes are supplied after a final sectionof filter with 2200 ohms and 10 id.The potential here is 150 volts.

The tube heaters are, of course,series connected across the line.

Philco Model 49-1606

ing variations on the usual PA sys-tem. The advent of the low impedance,moving coil and variable reluctancephono pick-up devices has made high-gain hum -free input stages manda-tory. Improved speakers and interestin wide -range sound has called forthimproved circuitry and layout.

The amplifier under discussion in-corporates many recent developments.Two have to do with the reductionof hum, particularly in the high-gain input stages, of which thereare two. One stage, using a 12SJ7pentode, accepts high impedancedevices. The other, utilizing a 12507

Partial schematic of Masco Model MA-25HF

Masco Model MA -25H1The current interest in high fidelity

reproduction of sound, particularlyrecorded music, has brought to themarket amplifiers containing interest -

dual triode, has a switch which per-mits connection of either high or lowimpedance' iources.,


1$ RADIO SERVICE DEALER DECEMBER, 1949

SHOP NOTESWrite up any "tricks -of -the -trade" in radio servicing that you have discovered.We pay from S1 to SS for such previously unpublished "SHOP NOTES" found

acceptable. Send your data to "Shop Notes Editor".

Gleaning CondensersWe often have occasion to clean

out dust lodged in variable condenserswhere ordinary pipe cleaners cannotbe inserted. For this use we havedevised the resonant high voltage,low current unit shown in Fig. 1.

which not only burns out every par-ticle of dust but also locates minuteshorts or tendencies in that direction.

Submitted by:Jack D. Garkim

Horicon, -Wisconsin

15H., 90 Ma.Depends on use

2

30 H. Limiter Choketo prevent throwing out

of resonance

0.5 Mfd., 1200 V. D.C.or more,

H.V. Cond.

Fig. I. Circuit of condenser cleaner

Westinghouse Model H-217-GroundConnection to Aquadag

Wear or vibration may sometimesdevelop a poor connection between theoutside coating- of the cathode raytube and its grounding springs. Theattendant arcing at that point canresult in tearing of the picture andinsufficient picture width.

To insure a permanent groundcontact, a piece of aluminum foil isinserted between the aquadag and thegrounding springs on later produc-tion models. This foil, one side ofwhich is coated with adhesive, is firstcut to a size of 1" x 11/2". One edgeis then folded 1/4" over the adhesiveside of the foil. Finally, the foil isplaced between the aquadag and thegrounding spring in such a mannerthat adhesive holds the foil to theaquadag, the spring bears againstthe uncoated side of the foil, and theuncoated side of the 1/4" fold bearstightly against the aquadag.

The foil is stocked in rolls of 20feet and can be ordered by part num-ber V-6237-2.

Repair Loosened Radio TubesA sure way to repair glass radio

tubes which have loosened from theirbases is shown in the accompanyingdrawing. Tie a piece of dial cord (orordinary string) tightly around thebase of the bulb where it enters thebase see Fig. 2. Then paint the cordthoroughly with coil dope, speakerdope, or collodion, allowing the dopeto run a sixteenth of an inch or soeach side of the cord onto the bulband base.

This makes such a tight seal thatthe bulb subsequently may be twistedwithout breaking its adherence tothe base.

This method may be applied withequal success to GT tubes, as well asto older style glass tubes. It workssatisfactorily with bakeilte, ceramic,and the other materials used for tubebases.

Submitted by:Rufus P. Turner,

919 East 116th, Pl.Los Angeles 2, Calif.

Tightly -tiedstring or cord

Fig, 2. Repairing glass tubes

Utility Heater

In order to heat plastic for bend-ing, and for drying parts that mayhave become water soaked or damp;as well as for other quick drying jobsaround the shop the item shown inFig. 3 works very well. It consistsof a 10 qt. pail with the handle legscut off, and an infra red bulb mountedas shown.

Submitted byMarion L. RhodesKnightstown, Ind.

PorcelainSocket

Infra -redBulb

1-Cut handle lugs off

Cord and Plug

10 -Quart' Pail

-Platform

Fig. 3. Utility heater details

Bendix, A -C D -C Chassis tubefailures

Some reports have been receivedconcerning tube failure in Bendixa-c/d-c 5 and 6 tube receivers.These reports come mainly from areasserved by the =LIZA or other powersources unable to maintain a reason-able stable line voltage. Since thetube filaments of a-c/d-c receiversare connected in series directly acrossthe 110 volt line, any great increasein line voltage may increase the volt-age across the individual filamentbeyond the rated maximum. This mayeither burn out one or more tubesimmediately, or, at least, seriouslyshorten the life of all the tubes.

To reduce this hazard a 75 ohm,3 to 5 watt resistor may be inserted inseries with the filament string. Aconvenient location in the Bendixfive tube chassis for this resistor isbetween pin 7 of the 12SA7 and pin7 of the 12SQ7. On the six tubechassis, this resistor may be insertedbetween the 14A7 and the 14Q7 byremoving the filament lead from pin8 of the r -f, 14A7, tube and mountingthe 75 ohm resistor directly on thetube socket lug.

Admiral 49C8-2 Tuners-FrequencyDrift

High ambient temperatures en-countered under certain operatingconditions may result in excessiveoscillator frequency drift in some9408-2 tuners. Under such condi-tions, frequent readjustment of thesharp tuning control will be neces-sary. In some cases, oscillator driftmay even go beyond the normal tim-ing range of the sharp tuning control.

This condition is most probablein 30D1 (16") chassis due to higheroperating temperatures in this model.

When excessive oscillator frequencydrift is encountered in a 94C8-2



NEW PRODUCTSNEW FM -TV TUBE

A new miniature tube (6BC5) designedprimarily for use as a radio -frequency andintermediate frequency amplifier in televisionand FM receivers is now in production at theOwensboro, Ky. plant of the General ElectricCompany.

According to J. M. Lang, Manager of theTube Divisions here, the 6BC5 represents an

improved version of General Electric's 6AG5and is interchangeable with that tube. Thechief difference is an increased transcon-ductance.

CONICAL ANTENNATricraft Products Company, manufacturers

of television antenna, has just announcedtheir new "300" Hi -Lo Conical Type X Antennaseries. These newly designed antennas are

pre -assembled at the factory, ready to install(no loose parts). They match 72, 150 and 300ohm impedance ; are all -wave, high gain onall channels ; and are durably constructed ofthe finest aluminum (will not rust).

CONTROLS MAY NOW BE GANGEDThe technician can now assemble his own

ganged controls in a matter of moments. Thereason is a completely new development incontrol units, pioneered by International Re-sistance Company. Known at Multisections,

these new IRC units are complete controlsections that can be added to any of the re-cently announced IRC miniature Q, PQ or1iQ Volume Controls, just as switches areattached.

NEW TV COMPONENTSSeven new picture i-f components giving

improved sensitivity, selectivity, and responsehave been announced by the Tube Department,Radio Coma of America, Harrison, N. J.

These new components are as follows: Con-verter Transformer, Type 202K5 ; 1st PictureIF Transformer, Type 202K6 ; 2nd Picture IF

2020

Transformer, Type 202K7 ; 3rd Picture IFTransformer, Type 202K8 ; 4th Picture IFTransformer, Type 202K9 ; 5th Picture IFTransformer, Type 202K10 ; and cathode -cir-cuit trap, Type 202K11.

NEW SYLVANIA TUBESThree new receivingtube types including

an audio frequency amplifier ; an r -f amplifierfor television ; and a horizontal deflection am-plifier for televison have been announced bySylvania Electric Products Inc., according toC. W. Shaw, general sales manager, RadioTube Division.

The audio amplifier, type 12AY7, is a T6%miniature, medium -mu duotriode particularlysuitable for use in the first stage of a -f am-plifiers where absence of noise and microphon-ism is desirable. The tube is supplied witha center -tap heater for use with 6.3 volt or12.6 volt source.

The r -f amplifier, type 6BC5, is a T5%mutual conductance, designed for r -f and i-f

amplifier applications in television receivers.The tube is listed as an equivalent of type6AG5 but it provides higher gain.

The horizontal deflection amplifier for tele-vision receivers, type 6BQ6GT, has been de-signed and processed for transformer operatedsets where high peak interelectrode voltagesare encountered.

RECTANGULAR 16 -INCH TUBEHytron Radio & Electronics Corp. announces

their new Hytron type 16RP4, a directly -viewed, 16 -inch picture tube with a rectangular

screen. Hytron claims it to be the shortest16 -inch picture tube on the market. The picture,with standard 3 to 4 aspect ratio, ha's ausable screen area of 138.7 square inches.No high -voltage isolation of the tube is re-quired. Magnetic focus and deflection are em-ployed. Complete technical data are availablefrom Hytron Radio & Electronics Corp.,Salem, Massachusetts.

YAGI ANTENNAA new Yagi, all highly efficient double folded

dipole television antenna has just been an-nounced by the Trio Manufacturing Companyof Griggsville, Illinois.

Its flexibility permits mountng of morethan one bay on mast with independent orien-tation of each. The new yagi is available onchannels 2 to 6 with mast and mounting hard-war'd, 'and for the high bands, less mast. De-scriptive folder is available from the manu-facturer.


CAPACITORSThe growing demand for a tubular capacitor

approaching the performance of a plastic -molded type yet available at a price closer tothat of conventional paper tubulars, is metby the Type '87 capacitor just announced by

Aerovox Corporation of New Bedford, Mass.This modified paper tubular features, Aeroleneand Duranite new impregnating and sealingmaterials developed by Aerovox research engi-neers and already the basis of the Duranitemolded tubula'rs in general use.

ROLLER BEARING GUY RINGCrown Controls Company, Inc., New Bremen,

Ohio announces the new Crown Roller BearingGuy Ring. This unit has been designed sothat the masts of antenna can be rotatedwithout loosening the guy wires.

TWIN -DRIVEN YAGIA new antenna design is realized in the

new Twin -Driven Yagi introduced by Tech-

nical Appliance Corporation, Sherburne, N. Y.Tests have proved the gain of this antennato be greater than any other antenna tested

line we ever stocked!Jobbers everywhere find demand for TelrexAntennas growing by leaps and bounds. Telrex-the conical "V" beam - is the one antenna thatguarantees your customers better, brighter pic-tures, longer service and no service call-backsdue to antenna failure. You can sell more an-tennas and your customers will sell more TVreceivers if you stock, sell and recommendTelrex, exclusively!

Lperfofimance6? Ogepprofits

ww"- /0/2,9tep se/VceTHE ONE ANTENNA LINE WE CAN RELY ONTO SOLVE EVERY INSTALLATION PROBLEM

That's the typical comment on Telrex Conical "V" Beamsfrom dealer and service man, alike. Special Series or De-luxe, every genuine Telrex Conical Antennais engineered and field-tested for better re-ception and durability in all TV areas.

ALL TELREX ELEMENTS ARE I

MADE OF HI -STRENGTH DURAL

PATENTS PENDINGCOPYRIGHT 1949

CONICAL

INC.

ANTENNAS

Telephone-ASBURY PARK 2-7252

AMERICA'S TiFirOUTSTANDING

TEI.EVISIONBEAM

ASBURY PARK 5, N. J.


at the Taco field and laboratory testinggrounds.

Ta'co claims to have designed and developedthis new type low -band antenna to overcomethe detrimental effects of parasitic elementsthat are used in all Yagi type antennas. Inthe usual type Yagi the mutual impedance ofthe parasitic elements reduce the impedanceof the array to a very low value.

CAPACITOR INDICATORA new capacitor code indicator just intro-

duced by the Sprague Products Company, '71Marshall St., North Adams, Mass. makes iteasy to decipher molded paper tubular capaci-tor color codings The Sprague Capacitor In-dicator consists of a pocket-size plastic device

with rotating dials printed in full and accuratecolors. When flicked to the proper color bands,the dials instantly indicate capacitance, toler-ance, and rated working voltage.

TELEVISION SELLSAlliance Tenna-RotorRphre4;fp /loge/

"50n:6e/re's-the, answerClearer pictures...

more stationsALLIANCE TENNA-ROTOR!"

4,500,000 ViewersAround 40 TV Stations

See TENNA-ROTOR in Action -Each week!Every TV set owner wants more distance-less interference-clearerpictures! Alliance Tenna-Rotor means faster antenna installations-fewer call-backs-happier customers! Guaranteed for one year!

ALLIANCE MANUFACTURING COMPANY Alliance, OhioExport Department: 401 Broadway, New York, N. Y., U. S. A.

ASSOCIATIONNEWS

Radio Technicians Guild of NewEngland

Whaling City Chapter,New Bedford, Mass.

The following is a copy of a news-paper clipping :

"Regulations governing the instal-altion of television antennae in NewBedford were drafted yesterday after-noon by the special committee onbuilding codes.

"Believed to be the first attempt ofa city to list specific requirements for

"(1

Group photograph of Whaling CityChapter members.

such installations in Massachusetts,the regulations were prepared by thecommittee, meeting with representa-tives of the Radio Technicians Guildfo New Bedford."

Our thought in attending this meet-ing to propose TV Antenna Code wasthat it would be better to take partin drawing it up, rather than com-plain about it after it was in force.

Dallas Radio S ales & S ervice Ass'n.,Inc,.Dallas, Texas

Dallas reports preparations for a TVAntenna Installation Clinic. This in-cludes a round table forum concerningproblems encountered in this area.TV set distributor reps have beeninvited to reveal how their particular-

receivers operate with different kinds-

of aerials. This is a good stunt andshould be emulated by other groups.

Lackawanna Radio Technicians Ass'n.Carbondale, Pa.

Michael Csigi was installed as presi-dent of the Lackawanna Radio Tech-nicians Association at a meeting re-cently in the Chamber of Commerce

-

Building. Leon J. Helk, past presi-d,;--t, was in charge.

Other officers inducted were: AugustCianchetti, first vice-president; Mer-


rill Greene, second vice-president;James Jerome, treasurer; Howard E.Greene, secretary; Homer Kinback,assisting secretary; Louis Perna,Stephen Csigi and John Riegel,trustees.

Robert A. Stang, executive of theJackson Instrument Co., New York,spoke on "Television Test Equipmentand Application."

Associated Radio -TV Servicemen ofNew York

The sixth lecture of the TV series,the title of which is, "Detector andVideo Amplifiers," was delivered inthe New York City Area by JohnMeagher of R.C.A., on Nov. 16, 1949.

RCA, Radio Service Dealer,and ARSNY group at lecture.

As usual, whenever Johnny speaks,the boys- were enthusiastic in theirpraise of his efforts.

Shown in the photo are (left toright) : Arthur Silverberg, Sec.; Ger-ard Nierenberg, Att'y ; Hal Bersche,R.C.A.; Max Leibowitz, Pres.; John

Meagher, R.C.A.; Sam Marshall, RadioService Dealer Magazine; and NoelPayne, Corr. Sec.

New Organizations FormedRadio Technicians' Assn.Station A, Box 1096Fort Smith, Arkansas.Mr. LeRoy RagsdaleConnecticut Television Technicians'Association29 Grenhart RoadStamford, Conn.Mr. Joe Di PretaFederation of Radio Servicemen'sAssociations of Pennsylvania

The Federation of Radio Service-men's Association of Pa. is setting uptheir Speakers Schedule for the entireyear of 1950. Leading manufacturerswill be contacted, requesting them toprovide a speaker on some subjectallied to their product. Any manu-

facturer desiring to have representa-tion by providing a speaker shouldwrite to :

Paul Smith, Program Chairman,306 Chestnut St., Harrisburg, Pa.

Dallas Radio Sales & Service Ass'n,Inc. Dallas 1, Texas

The third TV station for the Dallas -Fort Worth area will make its debuton Dec. 3, 1949.

Our brethren from the heart ofTexas claim that their prexy, E.Pflughaupt, is an old spook-his birth-day is on Halloween.

They also claim that June 7th, 1929,was the date of the first successful

TV telecasts in color, being done byold Ma Bell. Explain yourselves, pod-ners.

Longview Radio Sales & Service Ass'n.Longview, Texas

All of the service shops in Long-view, Texas, came together and agreedthat it was now time for them to havetheir own local organization. Theytherefore extended an invitation tothe Sec'y-Treasurer of the DallasRadio Sales & Service Ass'n., Inc.., tocome to Longview and set up anorganization for them. An organiza-

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to the famous GI phonomotor line today is being used in a widerange of portables, table models and console radio -phonographs.

Outstanding features: standard narrow -flange turntable for easy,

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TECHNICIANS AVAILABLECarefully selected group of trained men, grad-

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tion meeting was held on the eveningof Sept. 22, 1949 at the Hilton Hotelin their community. All shops wererepresented and a splendid spirit ofcooperation was evident. The organ-ization structure of the Dallas Ass'nwas fully explained and its many ac -

"X" ANTENNAS(Hi -Lo Conical Type)

e PRE -ASSEMBLED AT FACTORY,READY TO INSTALL (no loose parts)

Matches 72, 150 and 300 ohmimpedance All -wave, high gain on allchannels

Durable construction of finestaluminum (will not rust)

Quality at the right priceO Excellent all-around performanceeliminates constant servicing and maintenance

Tricraft "X" ANTENNAS are furnished in single,double or quad element assembly, with orwithout masts.

Model3200

Unique clomp simpli-fies installation-justpush in and tighten.

Available at leading jobbers.

Write for technical information, literature and prices.

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Manufacturers Is/complete line; of Television, FM and AM antennas and accessories

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Modern plan) built by Industrial Con-denser Corn., for manufacture ofCapacitors only.

complishments were recounted. Fol-lowing this the Longview Radio Sales& Service Association was organizedwith Mr. James Henry as Presidentand Mr. W. L. Beasley as Sec'y-Treas.They are already planning to extendinvitations to several nearby towns tobecome a part of their organization.It might be interesting to note thatthey voted to use the Code of Ethicsof the Dallas Ass'n in full. We cer-tainly congratulate them on their or-ganization and wish for them the verybest of luck.

SHOP NOTES[from page 19]

tuner, the following part change willcorrect this condition:Replace old part: C109, part #98A45-

28 (10 mmfd., -300 temp. coef.,ceramic capacitor).

With new part: 0109, part #65B6-33(10 mmfd., -750 temp. coef., cera-mic capacitor).

Capacitor C109 is accessible by re-moving the cover plate located on theside of the chassis pan, next to thetuner. Capacitor 0109 is connectedbetween the second turret contactblock terminal (from front of chas-sis) and ground.

After replacement of C109, theoscillator must be realigned by meansof trimmer i110. Realignment shouldbe made either with a TV signal onthe highest available channel in yourarea or on channel 13 with a signalgenerator whichever is more con-venient.

Motorola VT 71 RepairCustomer brought in this new 7"

electrostatic ac/dc model, complain-ing that after a week of excellentoperation, suddenly, during a pro-gram, the picture went out. Soundcontinued normal. This eliminatedthe low -voltage rectifier, sound andcommon r -f circuits. A quick check ofthe voltages on the other circuitsshowed them to be normal. Yet therewas no picture.

That started me to thinking. Asa routine check I had already touchedthe rectifier cap with an insulatedscrewdriver and drawn a nice bluespark. But, that, I realized, was noth-ing more than an r -f spark. Howcould I find out if there was d -chigh -voltage? The voltage chartsaid "DO NOT MEASURE" underthe 1B3GT. The 1B3GT couldn'tbe checked in the tube tester because

-; )here was the feedback gimmickaround it. (See drawing of H.V.Feedback Coil Fig. 4. Once I had the

it


drawing carefully ,made I removedthe coil and checked the 'rectifiertube. The filament was open!

It was just a few minutes' work tohook up a new 1B3GT, following thedrawing and the instruction data onlocation of the coil. That fixed it. If

Ir tat

1433GT

HIGH -VOLTAGEFEEDBACK COIL

----Tape around tube

"-Bottom edge of spring3/4" from tube base.

Spring coil cemented on.

Spring gimmick

H.V.05C.25L6GT

150 K

1 B3 GT

++

HIGH -VOLTAGE GIMMICK

Fig. 4. Motorola VT7I high voltagecircuit.

you're interested in just how thegimmick works, see the schematicdrawn for only the feedback sectionHigh Voltage Gimmick above.

Submitted by:David Gnessin

Columbus, Ohio

G. E. -Exchanging StylusThese are the two main steps neces-

sary to exchange the stylus of theGeneral Electric replaceable stylusvariable reluctance phonograph car-tridge. The upper picture shows howthe stylus can, be pushed out with a

Fig. 5. Exchanging styluscartridge.

RADIO SERVICE DEALER

in G.E.

paper clip, and the lower one showshow a new one can be pushed intoplace with only the fingers. Severaldifferent size stylii are available insapphire and diamond for use withall types of recordings, including thelong-playing records. Cartridges andstylii are being made at G.E.'s Elec-tronics Park at Syracuse, N. Y.

Admiral "30" - InterferenceBulletin TV -37 describes a remedy

for an interference pattern caused onChannel 5 from the sound carrier ofChannel 7.

In weak signal areas, there may berotating black bars on Channel 5

where Chanel 7 does not operate. Thisis caused by feedback from the lastvideo IF stage to the RF tuner input.The last vido IF stage generates astrong third harmonic of the videoIF frequency of 25.75 mc. This har-monic is 77.25 mc which falls rightin the Channel 5 frequency band. Thefeedback is caused by the piece oftransmission line in the set betweenthe antenna terminals and the tunerinput, being close to the last videoIF stage.

The remedy for this difficulty is toremove the piece of transmision linefrom the set, and run it down fromthe front of the chassis through the

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25

hole in the cabinet which is used forthe audio load. It can then be splicedto the antenna leadin somewheredown near the bottom of the cabinet.

We suggest that this remedy beused wherever this type of interfer-ence is present on Channel 5. Themethod outlined in TV -37 should beuser in those cases where the inter-ference is coming from Channel 7.In some cases, both types of inter-ference may be present so that bothremedies will be needed.Tube Base Connectors

The serviceman who has to gothrough a TV alignment often finds

Fig. 6. Tube -base connector.

it easier to do his aligning from thetop side of the chassis. For this reasonhe should provide himself with anumber of tube base adapters of thetype illustrated in Fig. 6. The illustra-

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tion shown refers to an octal tube.However, connectors may easily bemade for any tube.DeIcoA-C D -C Portables-Hum

A kink on the Delco a-c/d-cportables is as follows: Complaint iscontinuous a -c hum even after the setis turned off. Tracing the circuit Ifound that B- is above chassis. Theset uses a PM speaker with one sideof the voice cell going to chassis andto the secondary of the output trans-former. To correct this condition re-move these leads from chassis andconnect direct to a common terminalpoint insulated from chassis.

Submitted by;Al PratesiWhite Plains, N. Y.

CIRCUIT COURT[from page 18]

Whatever steps are taken to reducehum later in the circuit, it is alwaysa big problem to limit the generationof hum in the first stage. One of thesources which plagues designers is thea -c voltage appearing across theheater, and between the heater andcathode, of the input stage. Onemethod of holding this source of trou-ble to a low value is to use d.c. on theheaters or filament.

In the amplifier at hand, as shownin the partial schematic, a d -c sourceis used for the two input stage heaters.They are in series and across a 750ohm resistor from the cathodes of the6L6 output tubes to ground. Paral-leled with, them is a 50 Id electrolyticcondenser to maintain a very lowimpedance path for audio frequencies.

Another feature of the circuit whichwill permit some variation in com-ponents and tubes, and still make lowhum possible, is the variable resistoracross the heaters. The arm of thiscontrol is, connected to the cathodesof the 6L6 stage, thus placing all theheaters to limit the total voltagepotential above ground. This schemeis frequently helpful in removing anotherwise obstinate source of hum.

It should be noted that there is aresistor in series with the input tubeheaters to limit the total voltageacross them to 13 volts. The fullemission of the tubes is not needed inthe application at hand and tube lifeis increased many times by such areduction.

Although not shown, voltage feed -I -21k is used around the last twostages to give improved response andfurther reduce hum.


TV TRUCK

[from page 17]

installation medium is strictly pro-hibited.

Service Methods

L & S service is given in the fol-lowing way. Customers select thecabinet style at the store. Beforethere is any payment Mr. HulletShipman, the firm's TV technician,goes to the place of installation. Mr.Shipman has had extensive UnitedStates Navy training in radio, tele-vision and radar. Also arriving atthe home or office or store where thetelevision is to be placed is the Fordtruck. This is taken care of by Mr.Ralph Riggs and Mr. Tony Santos.

Within a half hour to forty-fiveminutes Mr. Shipman knows theright height. He directs the two menin the Ford at the task of raisingthe portable tower. One moves thetower up while the other watchespicture reception. A correct installa-tion can be made in three hours.This is a saving of eight hours byformer and more antiquated methods.

In the event that there is no pictureup to 70 feet the location is classifiedas a "dead spot." No charge is madefor the test unless it is outside of atwenty-five mile radius of Middle-town. Then a small service cost iscollected.

In the erection of about 175 setsonly 3 "dead spots" have been en-countered. In only a few instanceshave people objected to paying thecost of a tower that would have to beas high as 70 feet.

Middletown receives seven NewYork City stations on channels 2,4,5,7,9,11 and 13. Reception is called goodon the average. The surnnier drought,with lack of humidity, weakenedsignals to a slight extent. Foliagehas not cut down reception to thepoint where pictures could not belooked at.

Before the Ford truck and porta-ble tower were employed it was nec-essary to have three installationcrews. The new system finds L & Sattending to one job in a half hourtest with accuracy instead of theprevious method of taking four hours,or longer, for a rough guess. Imme-diately after the half hour findingsare made the Ford goes to anothertask. It can thus make a number ofcalls in a single day.

The L & S store is located on oneof the main business streets of the

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ImpedancePower Handling 8 watts

CapacityDispersion,

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Width, less screen51/4 in.

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HFT-100 with attached mounting screenfor 12" cone speaker $24.50 List Price

HFT-100 with attached mounting screenfor 15" cone speaker $26.50 List Price

Write to factory for Catalog RD -12

MARK SIMPSON MANUFACTURING CO., Inc.32-28 49th Street, Long Island City 3, N.Y.

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city. Television sales have been pro-gressive in the community which hasa population of around 22,000 people.Middletown is situated about 70 milesnorth of New York City. In OrangeCounty of the Mid Hudson ValleyMiddletown is the hub of the wellknown fruit belt and milk shedregion. Middletown is often spokenof as the typical small city of theEmpire State. By the end of 1949the retail sales volume is being es-timated at approximately $30,000,000compared to $25,000,000 in 1948. Tele-vision is definitely helping withthis above average little city busi-ness.

PHOTO -ELECTRIC

[from page 16]

til the same meter reading is obtained.The two samples are then comparedby noting the difference in the set-tings of the potentiometer. In thiscase, as in some others, color filtersare used so that light of only onecolor reaches the tube.

Sometimes it is necessary that fail-ure of the unit be guarded against.An example of this is seen in a deviceused to protect workers against in-jury in the operation of machinessuch as power shears, saws, etc. Abeam of light thrown across thedanger area of the machine is brokenwhen any part of the operator's bodyis in this area, and prevents the ma-chine from operating. Failure of somepart of the photoelectric safeguardmight leave the worker unprotected,probably without warning that he isnot protected. Just how such an oc-currence can be prevented will beseen in the illustration of Fig. 5.Three relays are used in this arrange-ment, Rya being the one which causesthe device to fail on the safe side ifa failure does occur. The circuit forRya is completed through the con-tacts of Ryi and Rye. One of theseis the usual relay which is energizedwhenever the light bean is broken,the other is a type which will dropout if the amplifier plate current isreduced or is interrupted. Notice thatfailure of the light source, phototube,amplifier tube or power supply isguarded against.

A smoke detector is shown in Fig.6. We have here an example ofequipment in which a change in lightintensity due to line voltage varia-tions is compensated for. Two photo-tubes are used and are connected sothat the current produced by onecancels that developed by the sec-ond. Since the unit is intended to

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detect the presence of smoke in aventilating shaft or duct, such a

provision is quite important, other-wise line voltage variations might re-sult in reduced lamp brilliance andso set off an alarm. Light from thelamp is focused on the mirror at theother side of the duct, whence it isreflected back to phototube A. At thesame time, light reaches phototube Bby way of the variable aperture inthe lamp housing. The size of thisaperture is adjusted until the lightreaching both tubes is the same. Thephototube currents are then balanced,and only a reduction in the amountof light reaching A (which would becaused by smoke in the duct) willcause the unit to function.

ELECTRONIC VOM

[from page 14]

audio frequency or radio frequency.The multiplier is necessary whenmeasuring an a -f voltage between 100and 1000 r.m.s. volts. The a -c voltagesbelow 10 r.m.s. are read on either ofthe two lower scales-the 3 or the 10volt scale. Voltages between 10 and 100r.m.s. are read on the scale marked"ac above 10". The audio frequencyvoltages between 100 and 1000-which

EIBIEEMEBBLIBEIREBIBBIIIEBB.11:11sommonismimuummilmummu Emu=====1:

Emponinummq ismimpummouiIan 11111111 owl l 7111111111NINIONEHRINNINEPINEPPIDIIRmIBINNI!!sraransomaniwasiweimmoraannonmilimuumimmintsumunimiumsniimmunimpjuguNimmilampoom

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to°

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Fig. 4. Effective input resistance andcapacitance of diode probe versus

frequency.

require the use of the multiplier, arealso read on this scale.

Applications

An electronic voltmeter of this typehas many specialized applicationswhich ordinary measuring instru-ments cannot adequately measure. Os-cillator grid bias may be measuredby virtue of the high input impedanceof this meter and it is a well-knownradio fact that the amplitude of theoscillation output is proportional tothe oscillator grid bias. Automaticvolume control (a -v -c) voltage mayalso be measured because the highinput impedance of the instrumentdoes not affect the circuit. As an out-put meter, the WV -75 A may be con-nected across the load resistor of the

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second detector in the TV receiveror across the limiter load resistor inthe FM receiver. Only a slight loadingeffect will be noticed, which permitsnormal operation of the receiver whilethe alignment is proceding.

Peak -to -peak voltage measurementsmay be made by multiplying the scalereading by 2.83 as shown in the illus-tration. This will allow the actualpeak voltage of a complex wave shapeor pulse to be read directly on themeter which is an extremely usefulfeature in television servicing. To-gether with r -m -s a -c voltage measure-ments, the dbm values (the numberof decibels above or below a referencelevel of 1 milliwatt in 600 ohms at1000 cycles) may also be read directlyfrom the meter.

SOUND I -F[from page 12]

electronically and automatically elim-inated from the circuit when its useis not needed.

Coupling MethodsCoupling methods in both standard

FM receivers and TV -FM sectionsconsists primarily of transformercoupling between the stages. Typicalones are shown in Figs. 1 and 2. Thecapacitors which make up the reso-nant circuit are usually fixed, andtuning-when necessary during align-ment-is done by adjusting the slugs.

Fig. 5. Capacity coupling in DuMontRA -I05

The small arrows indicate that thecoils are tuned by means of slugswithin the coil instead of capacitors.Figure 1 shows the small arrows point-ing either up or down. Many manu-facturers use this method to indicatewhether the coil is tuned from abovethe chassis or from underneath.

Some manufacturers (Such as Du -\font in the RA -105 TV receivers)use capacitor instead of transformercoupling. Figure 5 indicates thismethod. The plate coil and the grid


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coil are tunable by adjusting the metalslug, while the two capacitors, witha center common ground, give thedesired coupling. This method assuredover -coupling for wide -band response.

In the plate side of all the circuitsshown, a decoupling network is in-serted below the plate resonant cir-cuit. This resistor and capacitor ef-fectively isolates the stages fromothers, and thus prevents signal en-ergy feedback which would set theseamplifiers into oscillation. This iscommon practice with all i-f amplifiersas well as high gain audio stages.

Common I -F TroublesAs with most amplifiers, common

troubles fall into several categories.In the absence of sound, the tubesshould be checked first. Once the tubefactor has been eliminated, voltageand resistance measurements shouldbe undertaken, and signal tracing re-sorted to if necessary. Severe mis-alignment would, of course, also pre-vent the signal from getting through.Unless, however, the receiver has beentampered with, alignment should notbe necessary because the percentagedrift of i-f stages in broad band workis negligible. If the set had been play-ing well and suddenly stopped, thetrouble would not be with alignment.

A common trouble in i-f stages is adefective screen by-pass capacitor.Take, for instance, the capacitor atthe screen of the 1st sound i.f. ofFig. 1. If this capacitor opens, the1st sound i-f stage will go into oscilla-tion. In a wide band stage oscillationvirtually kills all signal, because whilein the oscillatory state the circuit Qrises. The high selectivity, and thesustained oscillations, will usually givezero sound output. Occasionally apartially defective capacitor will notreduce the sound to total zero, butwill bring it to such a low level thatthe sound is heard only faintly withthe volume control turned on full.

When this stage oscillates in a tele-vision receiver, it will feed back thisr -f oscillation into the picture i-fstages. The result then appears onthe screen as a pronounced herring-bone pattern with a reduction of pic-ture contrast. If this capacitor shouldshort instead of open, it would causeexcessive heating of the screen drop-ping resistor, for the shorted capaci-tor will raise to a high level the cur-rent flowing through the resistor. Anover -heated or burned out screen re-sistor should result in an immediatecheck of the screen by-pass capacitor.

Another capacitor which givestrouble is the decoupler capacitor pre-viously mentioned. When this capaci-tor shorts, the series resistor throughwhich plate current normally flows

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PHILADELPHIA, PA.-"Anchor Booster's consistency, its highgain and its perfdrmance in outer fringe areas have builtfor it a reputation which canna.t be beat in our area. Theexcellency of this product has opened up many televisionareas and many additional soles in Television Receivers,their component parts and accessories."RADIO ELECTRIC SERVICE COMPANY OF PENNSYLVANIA

Albert N. Kass, Sales Manager

;has establishedgeneral acceptance and good willfor all good boosters through its own

top-notch performance!Unanimous proven verdict of users. Anchor's engi-neering -nor will it ever be.The ANCHOR BOOSTER is built to help you makethe best TV installations possible for your customers.

Why then be satisfied with the ordinary? Anchorbuilds demand for reliable boosters-making moresales-adding good will. Tie Anchor Booster intoevery television sale.Here is dependability with instant sales appeal -21/2 times average gain (Voltage Ratio), guaran-teed coverage of low and high band - precisionwith beauty-pride in having the best!

Get in touch with your jobber-or write ANCHOR

"ANCHOR ENGINEERING ALWAYS A YEAR AHEAD"

ANCHORRADIO CORP.

2215 S. St. Louis Ave.Chicago 23,

NEED

HELP?

TRAINEDMEN

AVAILABLESolve your trained man-power shortage by em-ploying C.T.I. gradu-

ates. These men have completed a rigidcourse of training. What they've learnedhas been PRACTICAL, because most oftheir training period was spent IN THESHOP. We probably have graduates fromyour area. Write for prospectus on Avail-able men. (No employment fees).

COMMERCIAL TRADES INSTITUTE1400 Greenleaf Dept. P 105-12 Chicago 26

RADIO SERVICE DEALER s DECEMBER, 1949 31

MOLDED TUBULAR PAPER

CIE

PAM ORS

11

11

NEW BEDFORD MASSACHUSETTS

DURANITE1600 t""c.

Initial -equipment Duranite -RMA color-coded-values im-mediately read on the wallchart. Replacement Duranite avail-

able through jobbers-valuesstamped on units for directreading.

Save time, trouble, mistakes! Thiswall chart gives direct readings for thoseinitial -equipment RMA color -coded mold-ed tubulars - capacitance, tolerance,voltage - at a glance. Handsomelyprinted in full color. And it's FREE! Getyours from your Aerovox jobber.Order the corresponding Duranites forprofitable servicing.

AIROY413 CORP.,NEW BEDFORD,MASS.,U.S.A.

bport:13 E. 40th St, New York16. N.Y. Cable: 'AHAB'

b Canada: AIROYOX CANADA lit, Namlites. Oil

will overheat or burn out. Here again,an overheated or defective resistorcalls for an immediate check of theby-pass associated with it.

Poorly soldered joints on coils, oftencause loss of plate current and signal.The i-f transformers in FM sectionshave few turns on them, because thehigh frequency at which they workrequires little inductance. The mostcommon trouble encountered is anopen circuit where the hook-up wireis supposedly soldered to the coilproper. All terminal connectionsshould be checked before replacementis attempted, for often repairs can bemade and the cost of the i-f trans-former saved.

A shorted cathode resistor by-passcapacitor (See Fig. 1, 1st sound i.f.stage) will result in loss of bias. Thiswill cause distortion of the sound out-put, and will manifest itself in ex-cessive plate current. A voltmeterplaced across the cathode resistorshould show a voltage with the polar-ity as indicated in Fig. 1. A voltmeterplaced from grid to cathode, shouldshow a minus potential on the gridof the tube. Zero potential, or plus,indicates a shorted cathode section, ora gassy tube, unless the value of thecathode resistor is extremely small, asoccurs in some circuits.

AD INDEXAerovox Corporation 32Alliance Manufacturing Co 22American Television & Radio Co 29Anchor Radio Corp 31

Astatic Corp., The 30

Channel Master Corp 2, 3Commercial Trades Institute 31

Drake Electric Works, Inc 31Duotone Co., Inc 26

Eastern Technical School 24

General Industries Co., The 23

Heath Company 30Hytron Radio & Elec. Corp Cover 3

Industrial Condenser Corp 24International Resistance Co 25

Ken Rad Tube Div. of G.E. Co 5

Mallory & Co., Inc., P. R Cover 2Mark Simpson Mfg. Co., Inc 27

Ohmite Mfg. Co 29

Radiart Corporation, The 1

RCA (Electron Tubes) Cover 4RCA (Test Equipment) 8

Rider Publisher, Inc., John F 10, ......Sonotone Corp 28Sprague Products Co 6Strand Hotel 32Sylvania Elec. Prods., Inc 7

Technical Appliance Corp 27Telrex, Inc 21

Tricraft Products Co 24

Western Coil & Elec. Co 28

14."' ATLANTIC CITY'S

IDEAL CONVENTION HOTEL

Exceptional Convention Facilities adap-table to small, medium or large groups.Ample Meeting, Banquet and ExhibitionRooms. Wonderful location Boardwalkopposite Steel Pier. Write ConventionManager TODAY.

The Strand features Spacious ColorfulLounges-Open and Inclosed Solaria-Salt Water Bath in rooms-Garage onpremises. Courteous Personnel.

When in Atlantic City visit

Famous Fiesta LoungeFood for Epicures

Exclusive Penna. Avenue and Boardwalk.


ANOTHER HYTRON FIRST YOU'LL BE BUYING SOON

NEW HYTRON

RECTANGULARall -glass 16RP4

Meet Hytron's space and money saver. The new Hytron 10.1)1Revolutionary 16 -inch rectangular picture tube. Takes approximatelysame cabinet space as 12LP4. Automatically sets the pace for morecompact and economical TV set design. You'll be seeing it ... buyingit . .. soon.

The new 16RP4 is latest in a long series of Hytron firsts. Including:The GT tube. Over 50 GT types. The subminiature. Many new minia-tures. Special low-cost TV deflection -circuit tubes: 1X2, 6BQ6GT,6U4GT, 25BQ6GT. Check the 16RP4's many features. Watch for it.Buy the best by the leader. Buy Hytron!

MAIN OFFICE: SALEM, MASSACHUSETTS

-"IttlartiPW'With old-style round tube,you lose the corners.

With Hytron 16RP4, yousee the picture just astransmitted.

Features of HYTRON 16RP4

Rectangular shape permits smaller, less costlycabinets.

Also just as short as 1211'4

3 Weight is approximately two-thirds that of 16 -inch, all -glass round tube.

Easy to mount. Can't roll or twist.

No high -voltage isolation of tube required.

Neutral gray face ... increases contrast ratio.

Large viewing screen. You get the entire trans-mitted picture; no lost corners. Gives picture (withstandard 3 by 4 aspect ratio) 101/4 inches by131/2 inches.

7,

Good aveeT. voa vezew voa vTok\ks

these aTe ow- vi\snes yo.), kox

Ov\smas and tne. NoN Ners.

RADIO CORPOIRATIONof AMERICA

HARRISON,.;

460,

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N THIS ISSUE - worldradiohistory.com · satisfies customers and brings them back for more, year after yfar, the reason is simple. "It's quality. Quality and value that stand out