Distribution of This Issue 50,000 Copies

JANUARY, 1950 cau.t.sy WOR-TV

CIRCUIT LOSS IN SIMPLE CENTER -FEO TV ANTENNASBy ARNOLD B. BAILEY

In television receiving antenna practice,it is imperative to cover a wide band offrequencies far exceeding the normalcapabilities of any one simple center -fedantenna. The TV channels when rep-resented on a frequency -ratio basis bringthis out clearly. Table 1 shows presentchannels on the basis of the nominalcenter frequency and the appropriatelimits to be covered by the proposed vhfchannels. Even if a separate simple anten-na is used for each of the three bands,the problem, although vastly simpler, isstill formidable. For the present, we shallconsider only the circuit problem, andevaluate the mismatch loss which directlyaffects the magnitude of the received TV

signal, and which will probably be presentwhen one simple center -fed antenna isoperated over a wide frequency band.Another distinctly separate factor relatesto the directional response changes whichoccur over a wide frequency band. Thesedirectional response changes will be treatedlater.

Editors Note: This material is anabridged excerpt of the same sub-ject as found in "Theory and Prac-tice of 30-1,000 Mc Receiving An-tennas' a forthcoming book whichhas been written by the author ofthis article and will soon be publish-ed by John F. Rider Publisher, Inc.

The receiving antenna as a circuitelement can be considered as a generator.This generator tries to pump power intothe antenna load and can only do sowhen the load is properly matched to theantenna. We can fix the load resistanceby proper selection of the TV receiverinput circuit constants and choosing atransmission line to correspond to thisreceiver input resistance. This fixed loadresistance can be made the same valuefor all TV channel frequencies.

The simple antenna, however, has a dif-ferent value of resistance at each fre-

quency, which will prevent a perfect matchat more than one frequency. At its res-onance frequencies the antenna is "in tune"and its Q (ratio of reactance to resistance)is zero. At other frequencies, the antennais out of tune; the Q is finite and willcause further mismatch losses. Thus wesee that we can only have a perfect matchat one frequency, and this frequency must,for simplicity, be one of the antenna's res-onant frequencies.

This brings about at least three possibleways of selecting load values for a simpleantenna. One way is to use a low -loadresistance value which equals the antennaresistance at the half -wave resonant fre-quency. Another way is to use a high-

load resistance value which equals the an-tenna resistance at the full -wave resonantfrequency. A third possibility is to usean intermediate -load resistance value, thegeometric mean of the other two values.

Fins. 1, 2, and 3 show these three casesfor four simple center -fed antennas. The

(Please turn to page 12)

Successful Servicing, January, 1950

TeIwidio#z etaGeneral Electric 811

The Model 811 chassis is similar to thatof the 810, which appears on pages 2-22through 2-43 of Rider's TV Manual Vol-ume 2, except for the changes describedin the following paragraphs.

When making video i -f alignment, adjustthe signal input to each stage to develop4 -volt peak at the video detector (junc-tion of L16 and C27), as measured witha calibrated oscilloscope, with a contrastbias of -4 volts.

When making audio i -f alignment, adjustthe signal input to each stage to give14 -volt peak at the limiter grid (junctionof R104 and C100), as measured by acalibrated oscilloscope, with a contrast biasof -4 volts.

Two types of ion traps were used onthis model. One is a single assembly, theother is a rubber sleeve with two magnetrings. Both types should be adjusted togive maximum brightness on the screen.To adjust the first type, it is necessaryto put the trap around the neck of thetube with the arrow pointing toward theface of the tube. The assembly shouldthen be rotated and moved forward orbackward to give maximum brightness. Ifthe illuminated area gets too bright, reducethe brightness control and readjust theion trap for maximum brightness. Thesecond type of ion trap is a rubber sleevewith two magnet rings, one large and onesmall. The trap should be mounted onthe tube neck between the focus coil andthe tube base, with the smaller magnetring toward the focus coil and the largermagnet ring toward the tube base. Theapproximate adjustment requires that thegaps in the two magnets be lined up withthe break in the rubber sleeve.1 With brightness control advanced, turn

ion trap assembly so that the gap inthe rubber holder is faced up or downand lined up with either pin no. 6

or pin no. 12. Whichever way givessome illumination is the correct ap-proximate orientation of assembly. Ifthe tube. V12, is removed, it will befound much easier to adjust formaximum illumination since the result-ant thin line will show illuminationeven though the magnets are con-siderably out of adjustment.

2. Move the assembly back and forth, androtate it while viewing the screen formaximum brightness.

3. If illuminated area gets very bright,reduce brightness control and repeatStep 2. If tube V12 was removed,replace it before proceeding with Step4.

4. If any shadowing of the tube neck ispresent after completing Step 3, rotatethe small front magnet to correct theshadow, and repeat Steps 2 and 3.

Early production used a ten -inch speaker,while late production uses an eight -inchAlnico PM speaker.

Early production used a coil L5 in thegrid circuit of V17. This was changed to

a transformer 1'21 with tap 1 connectedto R101 and capacitor C106, 5,000 µµf(which is connected to ground), tap 2

connected to the plate of V22, tap 3 toground, and tap 4 to grid 1 of V17.

Bias voltage was added to the grid ofV2 -B converter, by a circuit consisting ofR120, 1 megohm, R121, 1 megohm, C113,5,000 µµf, and R4, to prevent the videocarrier from modulating the audio carrierand causing a buzzing sound in the audio.R121 and C113 are connected in parallelto ground and the junction of R4 andR120, which goes to the junction of RSand C19.

A circuit consisting of R118, C109, C110,and C104 has been added to improveblanking of the vertical retrace. This isshown in the accompanying diagram.

A[(+I]r..RAnI

111. C

A

12BLACK

R91IMEG

YEL

KM) 61092.7K T.oeMFa

R112270K

Circuit changes for General Electric 811.

An R -C filter, R38 and C46, 20 µf, wasadded to the primary of the vertical out-put transformer T15, to remove the ver-tical sawtooth wave from the B+ linewhich in some cases caused buzzing inaudio.

Ciii, a 5,000-µµf capacitor has been ad-ded to the filament of V10 to remove abuzzing sound in the audio.

Model 811 Replacement Parts List is

identical to that listed for Model 810,except for the following changes.

These items listed in the parts list for810 are not used on 811:Cat. No. Symbol DescriptionCat. No. Symbol DescriptionUOP-577 Speaker -51/4 -inch PM

speakerRAB-077 Back-cabinet back coverRAV-059 Cabinet-model 810 cabinetRCE-071 C59,60, Capacitor-electrolytic

61,63RDW-010RJC-008

RJS-119RMM-081

RRW-029RTO-054RTP-062

Safety glass-cabinet glassConnector-picture tube

anode, connector assemblySocket-picture tube socketCushion-rubber cushion for

picture tubeR97 Resistor -0.65 ohm, 4 w, wwT17 Transformer-hor. sweepT 1 Transformer-power

transformer, 60 cycles.

These items are used on 811, and are notlisted for 810:

RAB-084RAV-072

RAV-084

RCE-093RDE-041RDW-017RET-002RHX-014RHX-015

UOP-867 Speaker-eight-inch PMspeaker, used on lateproduction 811

URF-047 R38 Resistor -820 ohms, 2 w,carbon

Back-cabinet back for 811Cabinet-for 811, using 10 -

inch speaker, ROP-018Cabinet-for 811, using 8 -inch

speaker, UOP-867RCE-084 C59,60, Capacitor-electrolytic

61,63C46 Capacitor-electrolytic

Escutcheon-knob escutcheonSafety glassIon trapLead damper and springCable-picture tube mounting

ring and spring assemblyRJC-002 Contacts-speaker contact

clips

RJC-011 Anode connector assembly-for picture tube

RJC-014 Connector-single female plugto connect yoke assemblyto chassis

RJC-015 °Connector-single male plug

connects yoke assembly tochassis

RJP-027 Plug-eight-prong male plugconnects yoke assembly tochassis

RJS-114 Socket-female socket con-nects to RJP-027 on yokeassembly

RJS-128 Socket-for picture tubeRMM-086 Cushion-for escutcheonRMM-087 Cushion-for safety glassRMM-099 Bracket-used with RMM-100

and RMX-126 for mount-ing yoke assembly

RMM-l00 Adjusting plate-with twotapped holes

Bracket-for adjusting andclamping deflection yoke

Spring-for mounting picturetube

Speaker-ten-inch speaker,used on early production

RTL-090 T2I Transformer-lst audio i -fRTO-067 T17 Transformer-horizontal sweep

transformerRTP-300 T18 Transformer-power

transformer.

RMX-1 26

RMS-I65

ROP-018

RIDER TV MANUALS VOLUMES1, 2,

Sentinel 401, 402, 406These models appear on pages 3-8

through 3-17 of Rider's TV Manual Vol-ume 3. Glass breakage and prematurefailure of the 6AR5 tube may occur. Thishappens because the tube shield used overthe 6AR5 tube fits very snugly and ifthere are any minute flaws in the glassenvelope, the envelope will break due tothe expansion caused by the heat of thetube. When replacing 6AR5 tubes, do notreinstall the tube shield. This shield wasused solely to prevent the tube from drop-ping out of its tube socket during ship-ment.

Successful Servicing, January, 1950 3

Sentinel 400, 401, 402, 405, 406Models 400 and 405 appear on pages 2-1

through 2-13 of Rider's TV Manual Vol-ume 2 and on pages 3-1 through 3-7 ofRider's TV Manual Volume 3. Models101, 402, and 406 appear on pages 3-8through 3-17 of Rider's TV Manual Vol-ume 3. If tearing and picture breakup(noise streaks) occur when the set is jar-red, on early models 400, 401, 402, 405,and 406 television receivers using a 12AT7oscillator tube, it is probably due to aoose padder trimmer slug screw in C-11.The loose fit between padder trimmerscrew and the threaded sleeve prevent afirm grounding contact and result in abreaking up of the picture, noise streaks,and possible detaining of the receivedpicture. The installation of a locknut bush -mg, part number PST 500, on the paddertrimmer screw will hold the trimmer screwfirmly and provide a proper ground.

Slide the locknut bushing on a thinbladed screwdriver with the nut endtoward the handle and insert the screw-driver into the trimmer screw slot asshown in the accompanying diagram.While holding the padder trimmer screwso that it will not turn, slide the locknutbushing on the padder trimmer and turnit down by hand until it is tight againstthe front of the r -f tuner unit chassis.

Adjustment for the Sentinel 400, 401, 402,405, 406.

Industrial Television IT -35RThis chassis appears on pages 3-1

through 3-8 of Rider's TV Manual Vol-ume 3. The following changes are sug-gested to improve the video response:

Change the value of R42 from 10,000ohms, 1/E w to 3,900 ohms, Y2 w.

Add L30, a 470-4 peaking coil, betweenR42 and the junction of CR1 and C54.

All current production models of the35R -control chassis will have Standard Coiltuners instead of the G. I. tuners. Thephono-jack audio output and four -pinvideo and control -voltage plug will bereplaced by one octal plug.

TeIeitziion eitaff9esMuntz M169

This model appears on page 3-4 ofRider's TV Manual Volume 3.

The four 30,000 -ohm, 2 -watt resistorslocated in the horizontal hold circuit havebeen replaced by one 20,000 -ohm, 10 -wattresistor, number RW-2002-210.

General Electric 805, 806, 807, 809These models appear on pages 3-1

through 3-15 of Rider's TV Manual Vol-ume 3. Insufficient horizontal sweep widthmay be caused by a parasitic oscillationin the type 19BG6 horizontal sweep outputtube, V13. To correct this, connect a47-µµf, 500-v, mica capacitor, Stock No.UCU-1020, from pin 7 of the 19BG6 tubeto a ground lug of an existing terminalboard on the adjacent side apron.

RIDER MANUALS KEEP UP TO DATEFILL IN THE GAPS

CorrectionOn changes page 3-2 of Rider's TV Man-

ual Volume 3, General Electric 802 islisted as appearing on pages 1-28 through1-49,50 of Rider's TV Manual Volume 1.This should read "This model appears onpages 1-52 through of Rider's TVManual Volume 1."

Sears Service HintSince the failure of capacitor, C92,

0.01 µf, 400 volts, in some television chas-sis has resulted in the destruction ofseveral other parts, it is expedient toreplace it with a 600 -volt capacitor, be-fore turning the receiver on for its initialtest, as shown in the data for Model9119, which appears on pages 3-23,24through 3.32 of Rider's TV Manual Vol-ume 3, and for Model 9122, which ap-pears on pages 3-12 through 3-21,22 of thesame Volume. This change has been incor-porated in all chassis above serial numberB09 -T51016 for Model 9119, and aboveserial number B09 -T310002 for Model 9122.

It is not necessary to remove the chas-sis from the cabinet when making thischange. Remove the bottom plate fromthe cabinet on either the console or tablemodels with the cabinet on the side orupside down on protective pads. Thecapacitor C92 is mounted between pins 3and 5 on the 7AF7 horizontal oscillatordischarge tube. Unsolder the original partand solder in a good 0.01-4 600 -volt,tubular paper capacitor.

General Electric 801This model appears on pages 1-28

through 1-51 of Rider's TV Manual Vol-ume 1. Add a 13 -volt, bezel -indicator pilotlamp, catalog number UDI,-019, to thereplacement parts list.

"Did over $5,000 additional business installingESPEY chassis"

De Young, Ithaca, N. Y.

THERE ARE THOUSANDS OF OUT-MODEDRADIOS IN YOUR "BACK YARD" JUST WAITINGTO BE REPLACED ... AT YOUR SUGGESTION

Here is the custom-built AM -FM chassisthat means BIGGER PROFITS for you!

SPECIFICATIONSSupplied ready to operate, complete with tubes,antennas, speaker and all necessary hardware formounting in a table cabinet or console, includingescutcheon. Power requirements 105/125 volts AC,50/60 cycles. Power consumption -85 watts.Chassis Dimensions: 13/2" wide x 81/2" high x 10"deep.Carton Dimensions: (2 units) 20 x 14/2 x 103inches.Net Weight: 161/2 pounds each.Sold through your favorite parts distributor.

WRITE FOR CATALOGUE KDI2 CONTAININGCOMPLETE SPECIFICATIONS ON THIS

AND OTHER MODELS

The NEW ESPEY model 511FEATURES

I. AC Superheterodyne AM -FM Receiver.2. Improved Frequency Modulation Circuit, Drift

Compensated.3. 12 tubes plus rectifier and electronic Tuning

Indicator.4. 3 dual purpose tubes.5. Treble Tone control.6. 6 -gang tuning condenser.7. Full -range bass tone control.8. High Fidelity AM -FM Reception.9. Automatic volume control.0. 13 watts (max.) Push -Pull Audio Output.I. 12 -inch PM speaker with Alnico V Magnet,

25 watts rating.2. Indirectly illuminated Slide Rule Dial.3. Smooth, flywheel tuning.4. Antenna for AM and folded dipole antenna

for FM Reception.5. Provision for external antennas.6. Wired for phonograph operation.7. Multi -tap output trans., 4-8-500 ohms.8. Licensed by RCA.9. Subject to RMA warranty, registered code

symbol #174.

Makers of line radios since 1928.

TEL. TR,f,Igar 9-7000

MANUFACTURING COMPANY, INC.528 EAST 72nd STREET, NEW YORK 21. N. Y.

4 Successful Servicing, January, 1950

Heat is noProblem,

ate« gale l

MALLORYCAPACITORSCa.i Take It!

Mallory FP Capacitors are built to withstand continuous high

temperatures. Tests show they perform consistently during2000 hours of operation at a temperature of 185°F. At lower

temperatures, even longer !

Proof of this performance is found in the experience of onetelevision manufacturer, who kept records of field failures

for six months. Of 385,000 Mallory FP Capacitors in service

only six failed ! Special design and meticulous production

care make such records possible ... by eliminating the majorsource of interr al corrosion.

Mallory Capacitors have set new long -life standards for theindustry, yet cost no more. You will find it pays to rely onthe complete Mallory Capacitor line - paper -ceramics -FP Electrolytics.

See Your Distributor for Mallory Precision Quality Parts at Regular Prices

P R. MALLORY 8 CO Inc.

MALLORYCAPACITORS CONTROLS VIBRATORS SWITCHES RESISTORS

RECTIFIERS VIBRAPACK* POWER SUPPLIES FILTERS`Reg. U. S. Pat. Off.

APPROVED PRECISION PRODUCTSP. R. MALLORY & CO., Inc., INDIANAPOLIS 6, INDIANA

Successful Servicing, January, 19505

Vol. 11Dedicated to

480 Canal Street

uc'1cr.rtlfuL

SERVICINGREG. U. S. PAT. OFF.

JANUARY, 1950

the financial and technical advancement of theElectronic Maintenance Personnel

No. 3

Published byJOHN F. RIDER PUBLISHER, INC.

New York 13, N. Y.

JOHN F. RIDER, Editor

Copyright 1950, by John F. RiderNo portion of this publication may be reproducedwithout the written permission of the publisher.

CURTAIN TIMETVI And The Serviceman

For the benefit of those servicemen whoneed the information, TVI means televi-sion interference from a ham station. Thespread of television poses many problemsfor the operating amateur. Judging byreports from different parts of the countrywhere both hams and TV receivers are inuse, all operating frequencies used by theamateur station may produce interference.The conditions under which such inter-ference develops, and how they may becured are varied. We shall discuss someof these in this editorial, but the primarypurpose of this brief discourse is to bringto the attention of the serviceman thatthere is more to the solution of TVI thanthe simple advice to the TV receiverowner, "write to the FCC". The principleinvolved is: live and let live.

It would be ridiculous to deny that haminterference can prove annoying to theTV serviceman, and it is also true thatone cannot expect the television servicingindustry to serve as a liason between theset owner and the ham. It is, however,

equally true that when a TV antenna isbeing installed, it does seem silly to locateit within a few feet of a ham beam,especially when there is adequate roomelsewhere for the antenna. We recognizethat changing a position of a TV antennalaterally on a roof can materially alterthe character of the received picture, butwe repeat, that such changes will notalways destroy received picture clarity. Itmay mean a slight loss in signal strength,but in many large centers it can betolerated. Frequently, a very unhappysituation is created, because a ham whois operating his transmitter in accordancewith all of the FCC requirements finds itimpossible to go on the air during TVhours because the close proximity betweenhis and the TV antenna results in shockexcitation of the latter. Sometimes afundamental frequency (ham) trap at theTV receiver antenna terminals is a greathelp, but why create a situation if it canbe avoided.

We think that it is the responsibility ofthe television servicing industry to be as

familiar with the problems of ham inter-ference as it is for them to be familiarwith the various conditions which controlproper reception from a TV station - as-suming all other detrimental influencesabsent.

Neglecting for the moment the matterof justice, the rights of the ham cannotbe denied. They are not any more orany less than that right of the public toreceive a television picture without anyinterference. The television servicemanshould realize that both parties haverights, and that it is the responsibility ofthe serviceman to give proper advice tothe complaining receiver owner. It isneither just nor technically correct to dis-miss such interference conditions byrecommending a letter to the FCC.

Without question, numerous ham trans-mitters located in TV areas are emittingharmonics which are frequently the causefor TVI. The FCC has decreed that suchharmonic emission would be cleaned up;and in many cases, when this was done,TVI ceased. One manufacturer of hamtransmitters has designed his equipmentwith the elimination of TVI in mind, andthere is no doubt that others will do like-wise. However, it is also very significantto know that in some instances - andthese must be recognized - televisioninterference has reappeared; and uponinvestigation, it was found to be in noway connected with the ham transmitter,nor with the TV receiver itself. Thetrouble issued from corroded joints orpoor contacts in the TV antenna system.In it was not a ham problem,but rather a service problem.

We know only too well that the publicat large wishes to get the most for theleast - that people are not overanxiousto recompense a serviceman for anyspecial precautions which he may take ordesire to take to assure good TV recep-tion. Yet it cannot be denied that whenthe locale is such that a ham transmitteris in the proximity of a TV receiver, itis necessary to take the presence of that

(Please turn to page 15)

A -M AL AND TV HARRY AGREE .. .

Someñvq+ rr,ay faa!beret ewe

fb`beseirofrw4RA DIO,McTELEVI SIONSERVICING wrY.lf(,[NUINEAwo mar ott1ED

RIDER MANUALS

WHO SAID THERESNYArc( AM -

FM BUSINESSAROUND? l THATS RIGHT/THERE'LL

ALWAYS BEAM -FMBUST NESS -WOMEN (ANTCOOKAND CLEAN ANDWATCH TV TOOrln9

DID YOU SEE THE NOTICEFROM OUR JOBBER THATTHE NEW RIDER AM -FMMANUAL VOLUME 20 WILLBE OUT IN FEBRUARY?

YEAH, IDID-I UNDERSTANDIT WILL BE JAM-PACKEDWITH FACTORY -AUTHORIZED

DATA OF 74 MANUFACTURERS,COVERAGE UPTO THE END OF1949- - AND GET THIS -ALL PAGES

FILED IN THEIR PROPER PLACESWHAT A TIME SAVER THATS

GONNA BE!

7VHARRY

DO YOU KNOW AL,OURRIDER MAMMUALS

HAVE BEEN THE LIFE -LINE OFOUR-BUSINESSFORTHE PAST 2.1 YEARS -WED BE LOST IF WE DIDN'T NAVE ACOMPLETESET, INCLUDINGTHETVANDPA MANUALS!

YOU'RE DARN RIGHT HARRY, WE'VEKNOWN THIS FORA LONG TIME -

THAT'S WHY WE KEEPOUR RI DERMANUALS UP-1O-DATE,SOTHAT WE

HAVE IT WHEN WE NEED IT --

PPLACED OURORDER TODAY WITHOURJOBBER RDR RIDERS

VOLUME 20!

rl,

Successful Servicing, January, 1950

Sears 9123, 9124, 9126These models appear on pages 3-1

through 3-11 of Rider's TV Manual Vol-ume 3. If one of these sets cannot bemade to focus properly, the type of focuscoil used should be checked carefully andpossibly replaced. In original production,the horizontal output transformer producedan anode potential of approximately 7,500volts. This same transformer had a ten-dency toward short horizontal scan which,in many cases, was corrected by the ad-dition of a capacitor across part of thetransformer wiring. As soon as it was pos-sible, a horizontal output transformer wasincorporated which produced an anodepotential of 10,000 volts and developedmore than adequate scan. The higher -anode potential made it necessary to adopta new focus coil since the originalfocus coil would not produce proper focuswith potentials higher than about 8,000volts. A new focus coil can be identifiedby the fact that the back aluminum coveris not embossed the same as the frontcover. In addition, this focus coil, whichis an I.T.E. product, has four rivets hold-ing the two aluminum cover plates inposition and has six ears. The originalfocus coil, manufactured by G.E., has only

for OUTDOOR -INDOOR USE

SAFE I 1 I r/GUARDTwin Lead

Lightning ArresterProtects Television Sets Against $225Lightning and Static Charges

LIST

The ONLY Twin Lead LightningArrester Approved by UL for Out-door -Indoor Installation.

SIMPLE TO INSTALL ... attaches to any grounded ob-ject-pipe, radiator, roof, wall-at any position betweenantenna and the set, indoor or outdoor.

NO WIRE STRIPPING or CUTTING or SPREADING oflines necessary. 300 ohm impedance ... does notunbalance line.

One Dozen To Pack- Advertised in Conage with FREE Self- sumer PublicationsSelling Display Card. To Help Your SalesNo. AT102.12 01950, 1FD MFG. CO., Inc.

MANUFACTURING CO., Inc.6119 16th AvenueBrooklyn 4, N. Y.

FIRST /N rflfVISION ANTENNAS AND ACCESSORIES

four ears and the securing rivets arelocated in the ears. It is important tonote that the G.E. coil will focus over asecond -anode potential of 7 to 8,000 volts,whereas the I.T.E. focus coil will focusover a second -anode potential range of 8to 10,000 volts.

HIWYNI Have It WhenYou Need It

General Electric 801, 802, 803Model 801 appears on pages 1-28 through

1-51 of Rider's TV Manual Volume 1,and Model 802 appears on pages 1-52through 1-72 of the same Volume. Model803 appears on pages 2.1 through 2.21 ofRider's TV Manual Volume 2. The originalmolded horizontal sweep output transform-er listed for these models has beenreplaced by a new ceramic core sweeptransformer, Stock No. RTO-071. It hasseveral electrical design improvementsover the original specified transformer;among them are higher efficiency and bet-ter high -voltage insulation. The trans-former is equipped with a 470,000 -ohmresistor in shunt with a 0.0022-µf capacitor,connected between the primary and bywindings. In order to provide identicalelectrical characteristics to the originaltransformer, a few circuit revisions arenecessary when the substitution is made.The accompanying diagram shows the sixsteps required to adapt the circuit for thenew transformer. The numbers in thesquares correspond to the steps in theprocedure. Because the 801 schematicsymbol numbers are different from the802-803, the 801 numbers are shown inbrackets.

The procedure is as follows:

1. Disconnect leads of the old sweep out-put transformer and remove it fromthe chassis. Remove and discard the

'(NOT USED INMODEL 801)

C97(C 58)

4701 C95(C57)

C155

R85(R 42)

V 22(V 12)

V25(V13)

470K

/ItIl_ __1q-R114 {T25 6 /

(R 46) / (T9) 4701000

V

following parts: on Model 801-R107and width control, L7; on Models 802and 803-R126 and width control, L23.Mount new transformer on the chassisand connect it as shown to existingcomponents. In some Models 802 and803 a decoupling choke and capacitor,L2 and C154, were used between B+and primary of transformer T25. Leavethese in the circuit.

2. Change C95 (C57) from a 1,000-µµfcapacitor to a 470-µµf, 500 -volt micacapacitor. This is in the plate return,pin 5 of V21 (V11).

3. Add new width control and connect asshown. A secondary winding (leads-orange and black) is added to providethe necessary afc feedback voltage forthese receivers, which was originallysupplied by a tap on the transformer.It is very important to observe colorcoding when wiring in the control;otherwise the feedback voltage willhave improper phase.

4. Add a 470-µµf, 1,000 -volt, mica capac-itor between terminals 6 and 8 of thesweep transformer. Two 1,000-µµf, 500 -

volt mica capacitors in series may besubstituted.

5. Add a 10,000 -ohm, 1/ -watt, carbonresistor across R90 (R48).

6. Add a 68 -ohm, 2 -watt, carbon resistorin series with the cathode resistor, R123(R50) of V23 (V14).

7. Change C93 (C56) from 150 µµf to180 µµf. This is to assure that all re-ceivers will sync within horizontal hold -

control range.The new parts required are as follows:

Part No.RTO-071

RLD-017

UCU-1544URD-073

DescriptionCeramic iron horizontal sweepoutput transformer

Horizontal width control (includessecondary for afc feedback vol-tage)470 µµf, mica -C95 (C57)10,000 ohm, tit w, carbon

URF-021 68 ohm, 2 w, carbon(see substitute) 470 µµf, 1,000 v, mica (subs-

titute two 1,000 µµf, 500 v, StockNo. UCU-1052, in series)

UCU-2534 180 µµf.

8+ AFC FEEDBACK

R113(R97)

C 118T (C 66)

H. V.

V23(V14)

R121(R51)

(C31c1

Circuit changes for General Electric 801, 802, and 803. Circuit symbols in parenthesisdenote reference numbers for Model 801. A single resistor R45 replaces the paral-

lel resistor, R89 and R127 in Model 801.

Successful Servicing, January, 19507

In Fair weather

Not just a fair-weatherantenna but a year-round,all-weather Conical!

TA 161 ...Double "D-Xer" All -BandConical. y. wave -lengthstacked. Provides exception-ally high DB gain on bothbands. Channels 2 to 13.

TA 162...same as TA -161, but 1/2

wave -length stacked.

TA 160..."D-Xer" All -Band Conical,channels 2 to 13 and FM.Good front -to -back ratio onall TV frequencies.

TA 164..."Super D-Xer" DoubleStacked Conical, channels2 to 13 and FM. Completewith mast -supported alumi-num jt.mper harness. Unsur-passed for bringing in weaksignals over long distances.

Copyright, 1950, JFD Mfg. Co., Inc.

BUY YOUR TV ANTENNAS

AND ACCESSORIES FROM

ONE SINGLE DEPENDABLE

SOURCE OF SUPPLY

-JFD

r

The Sensational OD "D4er"All -Aluminum Conical Antennas

are STRONGER!Rugged construction. The only Conicals with reinforced elements. Will not bend, sag,sway or whip. Withstand all kinds of rough weather - wind, snow, rain, hail, etc.

MORE ECONOMICAUFeature -for -feature, quality -for -quality, performance -for -performance, JFD "D-Xer"All -aluminum Conicals give more for the money than any other antenna. The smart

serviceman looks for the reinforced element.

FASTER SEWNG IThe proof of a product's popularity is in the reorder. Daily, our list of reordersgrows longer and longer.

MORE PROF! TA8LE/"D-Xer" Conicals sell faster - more easily. They require minimum servicing. Once

put up, they stay put up - and they stay sold!

Write for FREE BULLETINSNow...right now...put your name on the 1FD listto receive informative bulletins of JFD "D-Xer"Conicals, and all other fast-moving, profitable JFDproducts.

MANUFACTURING Co., Inc.6119 16th AVENUE, BROOKLYN 4, N. Y.

FIRST In Television Antennas and A ones

8 Successful Servicing, January, 1950

WHAT MEDICAL TEXTSARE TO THE PHYSICIAN

RIDER BOOKSARE TO THE

ELECTRONIC TECHNICIAN

RADIO OPERATOR'S LICENSEQ AND A MANUALby Milton Kaufman

This book is a most complete and com-prehensive treatment of the subject andshould prove especially valuable as aquick review of essential theory, as wellas a refresher for advancement in thefield. It lists all the QUESTIONS andANSWERS for the FCC examinations.However, the outstanding feature of thisvolume is its thorough FOLLOW-THROUGH... a carefully simplified dis-cussion of the answer to the technicalquestion ... so necessary for a completeand absolute understanding of the ques-tion. Useful appendices, which includeSmall Vessel Direction Finders and Auto-matic Alarm, not ordinarily available ina book of this type, provide a valuable"extra". An indispensable reference vol-ume for the student and operator. 608pages. 193 explanatory diagrams.

$6.00FM TRANSMISSION and RECEPTION

by John F. Rider and Seymour D. UslanA "must" book for the radio serviceman wholooks to FM and television os an important partof his future earnings. Covers all types ofquency modulation systems employed in TV,radio, amateur radio, railroad, aviation, marine,police, point-to-point and mobile receivers. 416pages, profusely illustrated $3.60

TV PICTURE PROJECTIONand ENLARGEMENT

by Allan LytelTimely... Complete... Authoritative

Combines theory with practice, and offers aclear and well -organized explanation of thefundamentals of light, optics and optical sys-tems as employed in home television receivers,with emphasis on projection types and frontlens enlargement. 192 pages; 119 illustra-tions, charts. $3.30

BUSINESS HELPERby Leslie C. Rucker

(Rucker Radio Wholesalers)Written by a successful business man whostarted from scratch and worked his way up too chain of 3 stores. Any one of his manyworthwhile ideas can mean fifty times the costof this book in your pocket. 144 pages; 22chapters. $2.00

OTHER RIDER BOOKSThe Oscillator at Work. 254 pages $2.50B roadcast Operator's Handbook

278 pages $3.30Inside the Vacuum Tube. 420 pages $4.50Servicing by Signal Tracing. 370 poges $4.00Understanding Microwaves. 396 pages $6.00A -C Calculation Charts. 168 pages $7.50Vacuum Tube Voltmeters. 188 pages $2.50Radio Amateur's Beam Pointer Guide

32 pages $1.00Automatic Frequency Control

Systems. 154 pages $1.75Installation and Servicing of Low

Power Public Address Systems208 pages $1.89

Understanding Vectors and Phase158 pages Cloth Cover $1.89

Paper Cover $ .99Radar -What It Is. 80 pages $1.00

RIDER BOOKSJOHN F. RIDER PUBLISHER, INC.480 Canal Street, New York 13, N.Y.

Radàz G'lsanyetRCA 8V91

This model appears on pages 19-16through 19-25 of Rider's Manual VolumeXIX. The following changes in parts listhave been made:

Change:73753 Pull -

to read:73753 Pull -Door pull (2 required) for

mahogany instruments.Add:

74626 Pull -Door pull (2 required) forblonde instruments.

Philco M -12CThis model appears on pages RCD.

CH. 19-55 through RCD. CH. 19-74 ofRider's Manual Volume XIX. The threeparts referred to below were listed twiceín the parts list, and should be deletedas indicated.

Part No. Description56-464756-575376.4008

Retainer springPush -off saddleBase plate assembly

DeleteDeleteDelete.

Hoffman C503 and C513, Ch. 108These models are identical with Models

B503 and B513, which appear on pages17-8 through 17-13 of Rider's Manual Vol-ume XVII, except for the followingchanges:1. Push-pull parallel 6K6's are used in the

output stage instead of push-pull 6V6's.This is shown in the accompanyingdiagram.

Circuit changes for Hoffman C503 andC513.

2. On the recorder amplifier the screendropping resistor R11 has been changedfrom 0.1 megohm to 22 megohms. Thecathode resistor, Rl, for this stage hasbeen changed from 2,200 ohms to 4,700ohms. This allows the screen current ofthe 6SJ7 tube to be self-regulating andto eliminate variations in gain betweenvarious 6SJ7's.

3. R31 and C49 have been added in paral-lel to the Sl-sec 2, rear, wafer lead thatgoes to the phonograph receptacle.

4. Capacitor 030 is now connected to thevariable resistor, R20, instead of toground.

Farnsworth P-10This a -m -f -m radio chassis used in

Model 100-M, is identical to the P-10 chas-sis which appears on pages 19-19 through19-33 of Rider's Manual Volume XIX,with the exception of the phono-inputcircuit.

In Model 1001-M, the P-10 chassis em-ploys a 680,000 -ohm resistor, from phono-input to chassis ground, instead of a 100,-000 -ohm resistor, ref. no. 15.

Following is a list of parts which applyto Model 1001-M. These parts are dif-ferent from those shown in the Manualfor the P-10 chassis.

Part No.650183A -G1

750114B-1650189A -G1650186A-4650186A-2650186A-1650186A-3

Dc.ccriplionSpeaker, 10" PM, outputtrans. assy.Glass escutcheonLoop antenna assy.On -off volume knobTuning knobBand switch knobTone control knob.

RIDER MANUALS 2/(424 Sc FNU¿

SERVICNG

United Motors 984296Model 984296, Pontiac, appears on pages

19-60 through 19-64 of Rider's Manual Vol-ume XIX. The following change has beenmade in all sets above serial number691137 and B39-54401:

Illus. Production Service DescriptionNo. Part No. Part No.43 1213220 A 151 150 ohms, 1/2 w,

insulated.

General Electric 115, 115WThese models appear on page 18-13 of

Rider's Manual Volume XVIII. The fol-lowing changes have been made in theparts list.

Delete catalogue numbers and parts RDK-121 and RDK-122.

Add the following:RAG -019 Grille, for Model 115 and

115WRDK-150 Knob and bezel, brown, for

Model 115RDK-151 Knob and bezel, white, for

Model 115W.

Westinghouse H-203This model appears on pages 19.29

through 19-32 of Rider's Manual VolumeXIX. If bass response is objectionable, itcan be decreased by changing C29 from0.05 µf to 0.005 µf.

Successful Servicing, January, 1950 9

National Service HintsThe NC -183 appears on pages 19-11

through 19-35 of Rider's Manual VolumeXIX. Following is a list of troubles andsuggestions for correcting them:1. Oscillation in the E band at twice and

three times the i.f.a. Look for loose screws on sides of coil

compartment.b. Be sure second i -f and avc amp.

plate leads are down near the chassis.c. Be sure the diode leads of the 6116

are down near the chassis.d. Check ground leads on side of coil

compartment.e. Be sure that the first r -f grid lead

is down near the chassis.f. Cheek ground at the end of the

shield on the bfo lead near the 6116det. tube.

2. Oscillation at low end of the B band.a. Check ground on main tuning capac-

itor and the ground brushes on band -change switch shaft.

b. Be sure first i -f plate lead is downnear the chassis.

3. Pulling of signal with antenna trimmeron the A band.a. Check ground on band -change switch

shaft.b. Cheek ground from tie rod on tuning

capacitor to chassis.4. Motorboating with both r -f and audio

gains at zero.a. Check value of inverse feedback

resistor R47. This resistor should be4,700 ohms. A lower value than thiswill cause the motorboating.

5. Audio oscillation.a. Output transformer may be wired

wrong.b. Connecting leads to the transformer

may be reversed.6. Hum with limiter on.

a. Change limiter tube.7. Back lash in main tuning or bandspread

dials.a. Check end bearings of main tuning

and bandspread capacitors.b. Check tension of spring on antiback-

lash gears.

HIWYNI Have It WhenYou Need It

Zenith 8H832, Ch. 8E20This chassis appears on pages 19-16

through 1941 of Rider's Manual VolumeXIX. If replacement of one of thespeakers is required, care should be takenwhen connecting the new speaker in thecircuit so that the speakers are properlyphased. If the speakers are out of phase,all bass notes will be absent and distor-tion will be dominant. This condition canbe corrected by reversing the voice coilwires on the newly replaced speaker.

RCA 8X71, 8X72, Ch. RC -1070These models appear on pages 19-80

through 19-34 of Rider's Manual VolumeXIX. The driver tube (12AÚ6) cathoderesistor, Rll, has been changed from 180ohms to 330 ohms. .

WHAT A BASIC MEDICAL REFERENCELIBRARY IS TO THE PHYSICIAN...

RIDER MANUALSARE To THE ELECTRONIC TECHNICIAN

And, should you ask any Doctor-"What does your medical ref-erence library mean to you?"

His answer probably would be-"Medical science grows more com-plex every day. And while no mancan be expected to retain the mil-lions of details in his mind, he

MUST have them AT HIS FINGER-TIPS. My library furnishes me withCOMPLETE, ACCURATE andAUTHENTIC DATA. It gives me ollof the factual information that I

want... WHEN I NEED IT."

c11

x

{1t'1

And now, ask yourself-"WhatDo RIDER MANUALS mean tome?"Your answer probably would be-"Electronic science grows more com-plex each day. And while no mancan be expected to retain the mil-lions of details in his mind, he

MUST have them AT HIS FINGER-TIPS. My RIDER MANUALS furnishme with COMPLETE, ACCURATEand AUTHORIZED MANUFAC-TURER'S DATA. They give me allof the factual information that I

want ...WHEN I NEED IT."

RIDER MANUALSARE EQUALLY IMPORTANT TO YOU IN YOUR WORK!

TV MANUAL

VOL. 3* Larger Page Size, 12" x 15"!

All Pages In Place!

* Easier To Use!* Complete, Accurate, Authentic Data

Direct From TheManufacturers Themselves!

74 manufacturers. 441 models. 243 chassis.Easier to use than ever before. Diagrams andrelated text are more closely positioned. Giantpages have been retained, but now have onlyone fold for greater convenience and dura-bility. For greater efficiency, for more infor-mation, for more value for your money, orderRIDER TV MANUAL Vol. 3 from your Jobber!

Equivalent of 2032 Pages (81/2 x 11) Plus

RIDER MANUAL XAvailable Soon at Your Jobber's. Reliable, au-thentic, factory -authorized servicing informa-tion covering the latest AM -FM Radio, AutoReceivers, Record Changers, etc. Complete inevery respect, but with the added advantage oftext and double spreads assembled in position.More than 1700 pages. More than 70 manufac-turers. Price $18.00. Publication February 1950.

PLACE YOUR ORDER TODAY/ NOW?

RIDER MANUALSTelevision 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) $18.00

Volume XIX $19.80Volume XVIII $19.80Volume XVII $16.50

Volume XVI 8.40Volume XV $19.80Volume XIV to VII (each volume) $16.50Volume VI $12.50Abridged Manuals I to V (one volume) $19.80Master Index, Covering Manuals,

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

Cumulative Index Volumes 1, 2 and 3, NOTE: Are you receiving your copy of "SuccessfulPlus theBook

famous Rider "HowComplete

It Works"

$21.00Servicing"? It's Rider's own publication of interestto every Serviceman. Write for it ... it's FREE!

JOHN F. RIDER PUBLISHER, Inc., 480 Canal Street, New York 13, N. Y.Export Agents: Rorke Internotional Corp., 13 E. 40th St., N. Y. C. Cable ARIA6.

RIDER MANUALS mea« SUCCESSFULSERVICING

NOTE: The Mallory TV Service Encyclopedia, 1st TV Edition, makes reference to only one source of TV receiverschematics - Rider TV Manuals.

NOTE: The Mallory Radio Service Encyclopedia, 6th Edition, makes reference to only one source of radioreceiver schematics - Rider Manuals.

NOTE: The C.D Capacitor Manual for Radio Servicing. 1948 Edition No. 4, makes reference to only one sourceof receiver schematics - Rider Manuals.

io Successful Servicing, January, 1950

For TELEVISION, FM. and A.M.

RI

f.a

Zero Centeron ALL

VTVM rangesLarge

meter

demand aMODERN

lal/M-McBobmmeter

PRECISIONSERIES EVA

1O

Self-contained tAmPÓºo 60 volt -

- 2000 Megs -

Voltageranges to 60,000 V.

Vo TV Superwh- with Serie Test Probewhen used visionHlOh V olto9e

T ele

PLUS completetondard

sensitivity

51""aohms Per volt

functions

EV-10 is a WIDE -RANGE ZERO -CENTER ELECTRONIC INSTRUMENT.stressing the utmost in performance and ease of manipulation. ApplicationEngineered for rapid check of modern A.M.. F.M., and TV networks.

IMPORTANT FEATURES* VOLTAGE REGULATED-BRIDGE * MOISTURE RESISTANT, plastic insu-

TYPE CIRCUIT fated wiring assures performance* ZERO -CENTER VTVM-no polarity under adverse conditions.

switching or reversal of test prods. * DUO -BALANCED ELECTRONIC-* SHIELDED COAXIAL TEST PROBES. BRIDGE OHMMETER* 1% wire and metallized resistors. * 7" RECTANGULAR METER

RANGE SPECIFICATIONS* Eight Zero -Center VTVM Ranges, from * Eight A.C.-D.C. and Output Voltage

±3 to ±6000 V.D.C. Ranges at 1000 ohms per volt:* Input Resistance- from 0-3 to 6000 volts.

131/2 megs. constant to 600 volts. * Six Circuit Probing, Zero -Center,1331/2 megs. at 6000 volts. VTVM Ranges:

* Seven D.C. Current Ranges: from ;-3 to ±600 volts D.C.from 0-600 microamperes to 12 amps. * Eight DB Ranges. - 26 to 70 DB.

* Six Ohmmeter-Megohmmeter Ranges. * VTVM Ranges to 60,000 volts avail -self -contained to 2000 megohms. able via use of Series TV Test Probe.

SEE SeriesE-400 Wide

ASK TOSweep Signal Generator

Range 500 HighSensitivity 5"

Oscilloscope.tlries ES

catalogOscilloscope w 1949WRITE for THE PRESS) describing

OUSTaomplete "Precision" for allof

the test instrumentsphases of AM -FM -TV

service and

test.

SERIES RF-10 HIGH FREQUENCY PROBEAn accessory item to Series EV-10, the RF-10Probe provides direct voltage test facility toapprox. 200 MC. Connects directly to EV-10panel. Employs type 9002 tube. Net Price: $14.40

EV-10 MCP (illustrated) In open face portable steelcase. Complete with tubes, battery, and testprobes $89 95EV-10-P In closed portable case. $92.70EV-10-PM For standard rack mount __.$92.70

E- SERIES ES -500 -20 MV. High Sensitivity,Wide Range 5 inch C.R. OSCILLOGRAPH.

V. Amp. Response to I MCI Low C, High R input StepAttenuatorl Z axis modulation terminals? 9 tubes incl. V.R.and 2 rectifiers! Complete with light shield and mask.Heavy steel case 81/4 x 141/2 x 18" Net Price: $149.50

SERIES E-400Wide Range H.F.

SWEEP SIGNAL GENERATORDirect Reading

from 2 to 480 MC.

Narrow and Wide BandSweep for F.M. and TV

1500 pt. vernier calibrating scale MultipleCrystal Marker 8 tubes including V.R. andrectifier RG/62U Coaxial Terminated Output.Complete with 2 crystals. In heavy copper -plated case 101/2 x 12 x 6"___._Net Price: $124.70

PRECISION APPARATUS CO., INC92-27 Horace Harding Boulevard, Elmhurst 14, New York

Export Division: 458 eroodwoy, New York, U.S A Cables-Morhone

CIRCUIT PROBING WITH THE VTVM

Experienced television technicians know that theefficient way to run down sectional defects in atelevision chassis is to PROBE for the trouble.Such circuit probing is usually done with avacuum -tube voltmeter, and the measured valuesare checked against the mfr's. service data.

Circuit probing must frequently be performedunder dynamic (signal carrying) conditions and inaddition, numerous polarity reversals are alsomet in modern television circuits. For example.five positive terminals, and six negative terminalsappear in the typical sync network shown in Fig. 1.

-6.5

-2.1

FIG. I

-30

V2

i90

3

At first glance, it might be thought that polar-ity reversals could be taken care of by reversingthe test leads of the VTVM. Actually, this prac.tice can cause incorrect measurements, becausethe isolating probe of the VTVM is ineffectivewhen test leads are reversed.

For example, the -30 dc volts of signaldeveloped bias at the grid of V3 cannot be meas-ured by reversing the test leads. This bias iscaused by high -frequency pulses and flow of gridcurrent, - and the pulses are "killed" unless theIsolating probe is used at the grid of V3.

The return (ground) test lead of a VTVM doesnot contain an isolating resistor, but instead is adirect connection to the case of the instrument.It is easy to see that if the instrument case isconnected to the grid of V3, the heavy shuntcapacitance will "kill" (and/or short) the stage.

Signal -developed bias voltages can be meas-ured if the VTVM has a polarity -reversing switch,because the Isolating probe is then always inthe "hot" side of the measuring circuit. Suchswitches, however, are wasteful of both time andtempers. Note that five polarity reversals wouldbe required when probing the network of Fig. 1.

TIME IS MONEY IN THE BUSY SHOP, and it isvery important to use the right instruments forthe job.

The right answer to the television (as well asgeneral) circuit -probing problems is the ALLDirect -reading zero -center -scale as shown in Fig. 2.

y FIG.2e ass

When the VTVM is provided with such direct -reading zero -center scales, no polarity switch isused, and it is never necessary to reverse the testleads. Correct measurements will be obtained inall circuits, and no "figuring" is required.Polarity and magnitude are indicated simultane-ously In only one operation.

The direct -reading zero -center scale puts extrahours into every service day, and is one of thekeys to high-speed profitable servicing.

Engineering Division

Successful Servicing, January, 1950 11

a ad¿a ergZenith 7H822Z, Ch. 7E02Z

Chassis 7E02Z is similar to the 7E02which appears on pages 18-21,22 through18-25 of Rider's Manual Volume XVIII.On the 7E02Z receiver a tone control hasbeen added and a neon bulb on -offindicator. The accompanying figure showsthe tone -control circuit. The followingparts list shows the new componentsincluded in this receiver:Part No. Description

12-1546 Indicator socket brkt.14-857 Model 822Z plastic cab.22-1025 0.15 µf, 200 it, capacitor22-1511 50 µµf, ceramic 500 v, capacitor26-419 Dial scale46-769 Tuning & vol. con. knob46-770 Band -switch knob46-780 Tone -control knob46-781 Tone -control knob63-1744 100 ohms, ins. resistor, 20%, tfs w63-1884 220,000 ohms, ins. resistor, 20%,

tfa w63-2008 Tone control78-585 Indicator socket80-402 Dial cord tension spring83-1593 Felt strip (2 used)83-1595 Spacer strip93-961 Ins. shoulder washer

100-105 Neon indicator bulb199-35 Dial scale202-687 Instruction bookS-15325 Cab. back & plug cover assy.

The 220,000 -ohm resistor, R22, and theneon bulb on -off indicator have beeninserted from pin 4 of the 35B5 poweramplifier to ground.

Circuit

820 TONE CONTROL510%

changes for the ZenithChassis 7E02Z.

7H822Z,

RIDER MANUALS KEE UP TO DATEFILL PIN THE GAPS

National Service HintsThe NC -57 appears on pages 18-1 through

18-16 of Rider's Manual Volume XVIII.Following is a list of troubles common tothe NC -57 and suggestions for correctingthem:1. Audio oscillation with automatic noise

limiter (ANL) on and a -f gain on full.a. Dress the primary leads to the out-

put transformer under the ANLswitch. Pull the excess length ofleads through the hole to the top ofthe chassis.

2. Hum with ANL on and a -f gain onfull.a. Change the 6H6.

3.

4.

5.

6.

7.

Oscillation on B and C bands.Check C19 h -f ose. grid coupling capac-itor. This should be 100 µµF. A highervalue than this will produce oscillation.Also change the oscillator grid resistorfrom 47,000 to 22,000 ohms.Parasitic oscillation on A band above50 Mc.a. Check the ground lead of the r -f

amp. screen bypass capacitor. Thisshould be as short as possible andsoldered to the lug on the socketmounting ring adjacent to pin 4. Ther -f amp cathode bias resistor shouldbe 220 ohms.

Noisy band switch.a. Poor contacts in the switch, and poor

contact between the switch shaft andthe ground brushes on ER 210 coils.

b. Ground brushes on switch shaft rub-bing on the coil partition of the ER210 coils.

c. Coil partition mounting screws nottightened down.

Noisy trimmer control.a. Shorted plates.b. Poor rotor brush contact or rotor

brush not grounded to the mountingbracket.

c. Rotor shaft grounding spring on frontend of chassis is loose or missing.

Oscillation on E band at twice the i.f.a. Check to see that there is a metal

shield mounted on the trimmercontrol bracket.

RIDER'SVolume XX

Now on the press

more than 11700 pages all pages filed in place up to November 1949 a -m receivers f -m receivers record changers auto -radio receivers over 70 manufacturers

Net Price $18.00

Publication in February 1950

Order From Your Jobber

DEMAND FORASTATIC

Here's whatmakes the

CHANNEL

CHIEFTHE TOP

PERFORMER

AND THE TOP

SELLER

as EnthusiasticUsers Tell Others

USERS of the new Astatic Channel ChiefTelevision Booster are its most enthusiasticsalesmen. They are so delighted with the

highly improved reception they obtain that theyimmediately want their friends who own receivers to

enjoy the same new perfection. Result-demand hasmultiplied beyond all expectations, virtually overnight.Astatic's Channel Chief is a radically improved new type of booster,which brings amazing new quality of reception in "good" areas,good reception in previously "unsatisfactory" areas. It providesextremely high gain on all channels. Its dual controls allow separatetuning of picture and sound, with no sacrifice of one for the other.A variable gain control permits reduction of signal strength to preventpicture distortion when the signal input is greater than that requiredfor good definition. The selectivity of any receiver is increased, whichreduces drastically, or eliminates, interference from outside sources.Write for additional details.

The ASTATIC CORPORATION Conneaut, OhioIn Canada: Canadian Astatie, Ltd., Toronto, Ont.

Leading Manufacturers of Microphones, PhonographPickup Cartridges and Related Equipment

12 Successful Servicing, January, 1950

Circuit Loss in SimpleCenter -Fed TV Antennas

(Continued from page 1)four simple antennas differ from eachother only with respect to their thickness(or diameter). The factor P is arbitrarilyused to describe this thickness factor andrepresents the periphery, or circumference,of the antenna rod cross section expressedas a fraction of the free -space wavelength.Table 2 gives a physical picture of whatthe diameter of the four antennas wouldbe at 200 Mc where, as an example, wewill assume the antenna is operating as ahalf -wave antenna.

Table 2: 200 Mc Half -Wave Antenna

rrDf DP

11,800 18.8where P is in fraction of wavelength, Dis in inches, and f is in megacycles.

P Antenna Diameter(fraction of wavelength) (inches)

1. 0.00001 0.00022. 0.005 0.0943. 0.04 0.754. 020 3.76

The first case (Fig. 1) is only of theoreticalinterest, since its diameter is physically im-practical to use.

If we match these four antennas at 200Mc (the half -wave resonant frequency)the respective load values required willbe 72 ohms, 63 ohms, 46 ohms, and 35ohms. By inspection of Fig. 1, we see

this point is labeled f° - 1.0, where

f° is the standard half -wave frequency andfa, the signal frequency, which we will

vary. The loss at this point is 0 db, sincewe have chosen a perfect match at thehalf -wave resonant frequency.

Now if we depart from 200 Mc andexamine the antenna mismatch loss at anyother frequency, we can obtain the fre-quency ratio with respect to 200 Mcand note the corresponding loss insignal strength in db. It reaches highvalues at frequencies which are betweenodd resonant frequencies, as we wouldexpect. The losses are higher for thin thanfor thick antennas.

When we choose to match the sameantennas at the full -wave point (Fig. 2),the respective load values become 9,200ohms, 2,400 ohms, 960 ohms, and 290ohms. Except for the last case, thisprecludes the use of normal transmissionlines. It is of interest, however, to notethe broad simplicity in the results.

The third case, where the load is selectedto be the geometric mean of the half -waveand full -wave value (Fig. 3), requires loadresistances of 820 ohms, 370 ohms, 220ohms, and 110 ohms. By choosing thesemean values, the mismatch loss curve isquite constant with frequency ratios aboveunity. It must be admitted, however, thatthis third case does not fully match atany frequency and we can expect that thiswill give rise to the possibility of assistingsome reflections (line ghosts) at all fre-quencies. These reflections in the firstand second case were completely elim-inated at the matched frequency points,but became very serious at most otherfrequencies. The following approximationsin Figs. 1, 2, and 3 have been made:

TABLE 1. CHANNEL -TO -CHANNEL FREQUENCY RATIO

ChannelNumber 2 3 4 5 6 7 8 9 10 11 12 13 VHF'

Freq.Mc 57.5 63.5 69.5 79.5 85.5 177.5 183.5 139.5 195.5 201.5 207.5 213.5 500 600 700 800 900

2 57.5 1.0 1.1 1.2 1.4. 1.5 3.1 3.2 3.3 3.4 3.5 3.6 3.7 8.8 10.5 12.3 14.0 15.8

3 63.5 0.9 1.0 1.1 1.25 1.35 2.8 2.9 3.0 3.1 3.2 3.3 3.4 8.0 9.5 11.1 12.7 14.3

4 69.5 0.83 0.92 1.0 1.15 1.23 2.6 2.66 2.74 2.8 2.9 3.0 3.1 7.3 8.7 10.1 11.6 13.0

5 79.5 0.72 0.8 0.88 1.0 1.08 2.24 2.32. 2.4 2.47 2.54 2.62 2.7 6.35 7.6 8.9 10.3 11.4

6 85.5 0.67 0.74 0.81 0.93 1.0 2.08 2.15 2.22 2.3 2.36 2.43 2.5 5.9 7.1 8.2 9.4 10.6

7 177.5 0.32 0.36 0.39 0.45 0.48 1.0 1.04 1.07 1.10 1.14 1.17 1.21 2.8 3.4 4.0 4.5 5.1

8 183.5 0.31 0.34 0.38 0.43 0.47 0.97 1.0 1.03 1.06 1.10 1.13 1.16 2.7 3.3 3.8 4.4 4.9

9 139.5 0.30 0.33 0.36 0.42 0.45 0.94 0.97 1.0 1.03 1.06 1.09 1.13 2.6 3.2 3.7 4.2 4.8

10 195.5 0.29 0.32 0.35 0.41 0.44 0.91 0.94 0.97 1.0 1.03 1.06 1.09 2.6 3.1 3.6 4.1 4.6

11 201.5 0.28 0.31 0.34 0.39 0.42 0.88 0.91 0.94 0.97 1.0 1.03 1.06 2.5 3.0 3.5 4.0 4.5

12 207.5 0.28 0.30 0.33 0.38 0.41 0.86 0.89 0.91 0.94 0.97 1.0 1.03 2.4 2.9 3.4 3.9 4.4

13 213.5 0.27 0.30 0.32 0.37 0.40 0.83 0.86 0.89 0.92 0.95 0.97 1.0 2.3 2.8 3.3 3.8 4.2

V

H

F

500 0.11 0.13 0.14 0.16 0.17 0.35 0.37 0.38 0.39 0.40 0.42 0.43 1.0 1.2 1.4 1.6 1.8

600 0.10 0.11 0.12 0.13 0.14 0.30 0.31 0.32 0.33 0.34 0.35 0.36 0.83 1.0 1.2 1.3 1.5

700 0.08 0.09 0.10 0.11 0.12 0.25 0.26 0.27 0.28 0.29 0.30 0.31 0.72 0.86 1.0 1.1 1.3

800 0.07 0.08 0.09 0.10 0.11 0.22 0.23 0.24 0.24 0.25 0.26 0.27 0.63 0.75 0.88 1.0 1.1

900 0.06 0.07 0.08 0.09 0.10 0.20 0.20 0.21 0.22 0.22 0.23 0.24 0.56 0.67 0.78 0.89 1.0

Individual channels not shown.

a. Frequency ratios are plotted as if res-onances occurred at integral frequencyratios. (In practice, even resonancesmay be lowered due to the "physicalmismatch"; odd resonances may be

modified by smaller amounts. "Physicalmismatches" at even resonances wherethe wave energy is not highly localizedare due to the inability of this energyon the antenna to be "funneled" ef-

00

2

4

6

ó 8Ñ10

91214

Ñ 16 18

20

22

24

26

f X APPROXIMATE FREQUENCY RATIOf02 3 4 5 6 7 8

e

9 10

MNiN idib © /ilk .%1`N

IijIrI111/11uriiivii

/ 1 /

© ir' \IInr.

O©P=.005

©LOADO(p=.20

1

LO=AD02

LOAD

P=A4

LOAD1

=

=46

=1

THICKNESS

AT63

AT

AT35

1

OHfS/f0fx/Co

OHMS

fx/f0OHMS

fx/f0OHMS

1

-

=

1

FAC

=1

= 1

1

1

1

T ORP -ANTENNA

II

I

AS

fx=f0,A HALF

ANTENNA-WAVE ANTENNA

OPERATESI WHEN

I

1

Fig. 1. The mismatch loss of a center -fed antenna over a frequency band is shown for thecase where the load is selected to match the antenna resistance at the half -wave point.

Successful Servicing, January, 195013

0 0

2

4

6

8

Ñ 10OJ

12

Ñ 16

5 18

20

22

24

1

fx APPROXIMATE FREQUENCY RATIO

fo2 3 4 5 6 7 .8 9 10

\\h.,fiÁk © iÍ

oIv/ P = ANTENNA THICKNESS FACTOR

AT fxifo=1O'P=.00001LOAD = 9200 OHMS

=1P=.005 AT fx /fa 1©LOAD = 2400 OHMS

P=.04 AT fx/fa= 1© = 960 OHMSLOAD

OP =.20 AT fx /fo = 1LOAD ='290 OHMS

Fig. 2. The mismatch loss is shown for the case where the load is selected to match the

antenna resistance at the full -wave point.

ficiently into the physically small trans-mission line over the right-angle bendbetween antenna conductor and line.The voltage maximum occuring for evenresonances at the load terminals willtend to exaggerate stray capacitance ef-fects in the presence of "physical mis-matches".

b. Minor variations in Fig. 3, which mayoccur in practice, are not shown. Thesemay cause the flat portion of thegraph to exhibit cyclic dips of 1 db

to 2 db between integral frequency

ratios.c. The antenna feed point is assumed to

be free of stray capacitance effects dueto "physical mismatch".

o

2

4

6

8

10

12

14

16

18

20

These approximations do not impair theutility of the graphs. The losses indicatedmay be considered as minimum values,which may be exceeded in practice, butare rarely less than indicated. There will,however, be slight shifts to lower fre-quencies at the higher orders of resonance.Figs. 1, 2, and 3 may then be consideredto be about the best possible simple ap-proximation to the actual situation.

Let us note some important conclusionsfrom these graphs. If we match an antenna at any resonance point, we find thatthe maximum loss at other frequenciesmay be relatively high. If we permit asmall constant mismatch, the third case(Fig. 3), we get a loss at all frequencies,

f APPROXIMATE FREQUENCY RATIOfo

2 3 4 5 6 7 8 9 10

rsO O O O

P-ANTENNA

©©P=.04

OP

?PLOAD

[PLOAD

LOAD

LOAD

=

- .005

= .20

THICKNESS

- 800001

= 370

AT= 220

AT=110

AT20

ATOHMS

fx/f0

fxOHMS

OHMSfx

fx /'f0

OHMS

if()=

FACTOR

/f0 =

-1

= 1

1

1

II

1

Fig. 3. The mismatch loss is shown for an intermediate case where the load matchesneither the full- or half -wave point, but is equal to

Rmax Rmin = 0.59 ZA.

but it is much less than the maximum

loss for the first case (Fig. 1), or thesecond case (Fig. 2). Furthermore, themaximum losses of the first case and thesecond case are approximately equal.

A further precaution is in order. Theloss figures of Figs. 1, 2, and 3 take intoaccount only losses produced by circuitconditions at the antenna load, as the fre-quency is changed. We will see presentlythat we must also evaluate the signal loss(or gain) due to the variation in direc-tional response of the antenna with fre-quency.

This completes the determination of theamount of power absorbed by the antennaload for various types of center-fed anten-nas having uniform cross section, whenoperated close to the half -wave point orover a band of frequencies.

The practical necessity of consideringantenna loads which are not a pure resis-

tance, as may be the case when the antennais connected to the transmission line, willbe considered later. When the far end ofthe transmission line (at the radio re-

ceiver) is terminated in a matching resis-tance equal to the characteristic impedanceof the line, the antenna itself will alsosee a resistance load equal at all fre-

quencies to the transmission-line surge orcharacteristic impedance. When the lineis not properly terminated, the antennawill see a load consisting of a resistanceand a reactance, each varying with fre-quency. This case may give rise to dif-

ferent loss values, some higher, some lowerthan those shown on Figs. 1, 2, and 3,but in no case will the over-all trend ofthese graphs be improved. Essentially, theloss graphs will be modified by substantial"wiggles" or variations around the valuesindicated. The number of wiggles per unitchange in frequency will be small if theline is short in terms of wavelengths. Ifthe line is long, the number of wigglesper unit frequency change will be great.The amplitude of the wiggles will dependon the line loss and the degree of mis-match at the receiver end of the line.This condition will be treated later as at-tributable to the line and receiver, andshould not be considered as a defect ofthe antenna.

By proper realization of the values ofmismatch loss for simple TV antennas,we shall better appreciate the action forthe more complicated forms of TV anten-nas. It is important to note that whathas been said about the mismatch lossfor the simple center -fed antenna does notdirectly apply to the conventional simplefolded -type dipole. The two differ sub-stantially from each other.

Thus it is evident that the choice ofantenna diameter and the choice of anten-na load resistance both serve either toaccentuate or to smooth out the matchinglosses of an antenna over a wide fre-

quency band. It is not surprising, there-fore, that the present TV channels are notall equally well received by TV receivingantennas. It is well to note that optimumresults for one particular channel maypreclude obtaining a good signal at someother channels, solely because of the cir-cuit losses between the antenna properand the antenna load.

14Successful Servicing, January, 1950

Coming soon-and worthwhile waiting for!The New

CATHODE-RAY TUBE AT WORKby Rider et al

More than 900 pages Completely rewritten from start to finish 81/2 x I I inches $9.00The NEW "Cathode -Ray Tube At Work" is about five times the size of the old standby which hasbeen the standard for almost 15 years. Almost 500,000 words and about 3,000 illustrations havegone into this new edition. Never has there been a book on this subject like this one!

EXAMINE THESE CHAPTER HEADINGS1. INTRODUCTION2. PRINCIPLES OF ELECTROSTATIC

DEFLECTION AND FOCUSING3. PRINCIPLES OF ELECTROMAGNETIC

DEFLECTION AND FOCUSING4. MECHANICAL CHARACTERISTICS5. THE ELECTRON GUN6. DEFLECTION SYSTEMS7. SCREENS8. SPOT DISPLACEMENT9. LINEAR TIME BASES (SWEEP CIRCUITS)

10. THE BASIC OSCILLOSCOPE11. SYNCHRONIZATION12. PHASE AND FREQUENCY MEASUREMENTS13. NONLINEAR TIME BASES

14. AUXILIARY EQUIPMENT15. TESTING AUDIO -FREQUENCY CIRCUITS16. AM, FM, AND TV ALIGNMENT17. TELEVISION RECEIVER SERVICING18. AM, FM, AND TV TRANSMITTER TESTING19. ELECTRICAL MEASUREMENTS, SCIENTIFIC AND

ENGINEERING APPLICATIONS20. COMPLEX WAVEFORM PATTERNS21. SPECIAL. PURPOSE CATHODE-RAY TUBES22. COMMERCIAL OSCILLOSCOPESAPPENDIX

I - CHARACTERISTICS OF CATHODE-RAYTUBES

II - CATHODE -RAY -TUBE BASES AND SOCKETSIII - PHOTOGRAPHY

The greatest, most complete reference book ever written on the cathode-ray tube! It is a practical,right -down-to-earth volume which will repay its buyer many times over.Place your order today. NOW! Make certain that you will receive your copy from the first print-ing. You will not want to be without this book.

And-

THE THEORY AND PRACTICE OF 30-1000 MC RECEIVING ANTENNASby Arnold B. Bailey

JMore Than 500 Pages Cloth Bound $4.50

The radio and television industry - the schoolsteaching electronics - antenna design engineers -all personnel interested in antennas have long feltthe need for a book which reflects world-wide know-ledge of the antenna art. This is a book, which not

I-Definition and Terminology2-The Television Signal3-Problems of TV Reception4-The Electromagnetic Wave5-The Radio Path6-The Theory of Signal Interception

only is practical in every sense of the word, butalso has that rare quality of clearly explaining thetheory behind the performance of every type of30-1000 Mc receiving antenna - it will enjoy yearsand years of use.

EXAMINE THESE CHAPTER HEADINGS7-The Center -Fed Zero DB Half -Wave Antenna8-Comparison of Zero DB Half -Wave Antenna9-Parasitic Element Antennas

10-Special Horizontally Polarized AntennasII-Vertically Polarized Antennas12-Practical Aspects of 30-1000 Mc Receiving Antennas

Here is that book - written by an individual with21 years of designing experience and closest asso-ciation with the practical aspects of the subject aswell. It is a book which will teach - a bookwhich every person interested in antennas will useevery day because of the facts and figures it con-tains. Well planned and clearly written - it is areal gem among texts and reference books.

In the main, it is oriented toward the televisionart, to serve all the men whose livelihood dependson getting the most out of an antenna system. It is,however, equally important to the antenna engineer,to every student who is studying electronics, toevery school where electronics is being taught, andto every ham. It is a singular book, the like of whichhas never before been written.

ORDER FROM YOUR JOBBER OR DIRECTLY FROM US.

Successful Servicing, January, 19501

Curtain Time(Continued from page 5)

installation into account when installingthe receiver. It would not do the servic-ing industry any harm to contact suchhams and to ascertain their operatingfrequencies, and even go so far as to add

a filter, which is comparatively inex-pensive, across the antenna terminals ofthe TV receiver, or to recommend to the

set owner that it be done. Who cantell how many more TV receivers will beinstalled in the same area? It may bethe easier path to ignore the existence ofthe ham transmitter, and to simply saythat it is the interference which issuesfrom the ham station, and let it go atthat, but that is not the soundest businesspractice. The only trouble with that lineof thinking is that quite frequently theham, in his defense - knowing that he isoperating his transmitter in accordancewith the regulations - will malign theservice organization and may even go sofar as to place the service organizationin a bad light by adding such a filter. Inmaking these comments, we are not ex-pecting the servicing industry to bearevery burden, but it is not stretching theimagination too far to visualize an instal-lation service organization doing every-thing in their power - naturally, every-thing within reason - to satisfy a cus-

tomer.Despite many expressions to the con-

trary, hams in the United States are notwillfully interfering with TV reception;they are cognizant of their responsibilityto the public and to the rights of thepublic, which is why in many parts ofthis nation, hams are conspicuous by theirabsence during TV hours. Every day moreand more hams are spending money toeliminate harmonic radiation and thusclean up TVI. This does not call forthanks on the part of anyone, but doescall for a little more consideration on thepart of the TV serviceman. In sayingthis, we are not whitewashing the entireham field because there are many whoare flagrant in their violations, and un-fortunately, the FCC neither has the manpower nor the funds to spot these stationsas rapidly as all might desire. Eventuallythey are caught up with, but in the mean-time, the servicing industry cannot indictthe entire ham activity because of a fewun -co-operative individuals.

Considering the legal status of the hamfield, there is much to be said for theapproach toward accomplishing an end.There is no harm in telling a TV setowner that his picture is being destroyedby a ham, and that as a servicing facility,little if anything, can be done by thatfacility to remedy the situation. This,of course, presupposes that corrodedjoints and poor contacts are absent inthe antenna system. However, it is wrong,no matter how you look at it, to arousethe ire of the set owner by condemningthe ham. It is just as easy to explain thesituation and if possible, to ask the setowner to get in touch with the ham.Nine times out of ten, they will arriveat an amicable solution, and no one'sprestige or reputation will be hurt.

What we are leading up to is that itbehooves the TV servicing industry to be -

conic more familiar with a ham transmit-ter, the manner in which harmonic radia-tion affects a TV receiver, and the meansof recognizing ham interference in contrastto other types of interference. It woulddo no harm if servicing organizationscontacted hams so as to learn more aboutI hem, especially the various means of cor-recting TVI at the receiver end. It is

important for the servicing industry tounderstand that the FCC, when respond-

ing to a complaint, invariably advises thecomplainant to communicate with the of-fending ham, and the recommendation isalso made that the receiver owner call

his serviceman to apply whatever cor-

rective remedies are possible at the re-

ceiver site. The ham is called upon to

clean up his transmitter but he is notordered by the FCC to take any cor-

rective steps at the receiving end. Some

hams, in their desire to co-operate, doinstall filters on receivers, but have beendiscouraged from so doing because in al-

together too many cases, a subsequentfailure in the receiver was wrongly at-tributed to the addition of such a simplething as a trap across the antenna ter-minals.

These remarks do not imply that simpleintercourse between people leads to anunderstanding and a resolution of all

problems. Personalities frequently conflict,

and where suspicion abounds or wheresome previous experience may have proved

(Please turn to next page)

"SERVICE?"(8inthedictionary...ad at yourTU1'JG'SOL.

PISTIBUTOR

Sure, when you place an order with a dis-

tributor you want it delivered promptly.That's service! And there's a distributorright near you to whom that word "service"means just that ... plus a lot more that ismighty valuable to you.

He's your Tung -Sol distributor and inaddition to getting your order to youquickly, service means keeping abreast oftechnical developments in radio and tele-

vision . . . being informed of the bestvalues in sets and components . .. know-

ing the requirements of his dealers andreflecting that knowledge in a full and

balanced stock of supplies ... keeping up

TUNG-SOLTELEVISION TUBES

RADIO TUBESDIAL LAMPS

with manufacturers merchandising plansso that you can take fullest advantage oftheir profit -making possibilities.

It is because of these service stand-ards that that distributor has his Tung-Sol

franchise. He carries a full line of Tung -Sol "vibration -tested" Radio and Televi-sion Tubes. They are made to higheststandards of quality which includes 77individual manufacturing tests. Give yourorders to your Tung -Sol distributor. You'll

like his service.

TUNG-SOL LAMP WORKS INC.Newark 4, N. J. SALES OFFICES:ATLANTA CHICAGO DALLAS DENVER

DETROIT LOS ANGELES NEWARK

ALSO AUTO LAMPS, ALL -GLASS SEALED BEAM LAMPS & FLASHERS

Successful Servicing, January, 1950

Curtain Time(Continued from page 15)

distasteful, the attainment of co-operationis difficult. Be that as it may, it does notdeny the continuation of attempts to co-operate. Such co-operation between a hamactivity and the servicing activity is mostimportant. Since the serviceman is inmuch more intimate contact with the TVreceiver, it seems only logical that the sug-gestion for greater co-operation be aimedat him. Ham activity is not apart fromthe radio industry - it is part and parcelof that activity and it must be recognizedas such by the servicing group. It can bea headache at times, especially, when aham refuses to co-operate. Such instan-ces, however, are infrequent rather thanfrequent, because every ham is anxious todo whatever he can to enable him to beon the air whenever he so desires.

It is silly for the serviceman. to malignhim - to disparage his usefulness or hishobby. While it is not our desire to laudthe ham on the basis of his best ac-complishments, the fact remains that muchscientific knowledge is still being ac-quired from ham activities. Maybe allthe hams do not contribute to it, butmany do. Their unselfish efforts duringemergencies cannot pass unnoticed - theirservice as a communication link betweenmilitary personnel all over the world andtheir families here in the United Statesmerits approbation - in other words, theactivity as a whole serves a purpose.

Hams and servicemen have been at log-gerheads for a long time, exclusive ofthose who perform both roles. The pos-sibility of ham activity being legally ban-ned as a result of TV receiver pressureis very remote. The possibility of televi-sion channels being changed or the hambands being changed is likewise remote, atleast for quite a few years to come. Thepossibility of TV receivers being designedin such manner as to preclude completelythe possibility of ham interference is like-wise a comparatively long way off. Inother words, the ham, the serviceman, andthe public will have to learn to livetogether. It can be done and it is beingdone. It may not be achieved successfullyin every single instance, but by and large,all can work together.

Admittedly, the magnitude of the televi-sion receiver industry overwhelms ham ac-tivity, but we cannot ignore the fact thatthe majority of ham installations in thecountry represent investments from fivehundred to many thousands of dollars. Itis not inconceivable that servicemen mightbe invited to attend ham club meetings

RIDER BOOKS IN PREPARATIONTELEVISION INSTALLATION TECHNIQUESIlere is a book written by an individual who has been in very close touch withthe problems of television antenna and receiver installation. As such, he isfamiliar with the theoretical and practical aspects of every phase of thisactivity. Ile has taken particular pains to present the mechanical, as wellas the electrical solutions, to numerous problems which may arise in con-nection with installations near transmitters and in fringe areas.

It is the only book of all those written which will give every installer of areceiving system the information pertaining to the antennas, transmissionlines, receiver adjustment, and above all, the mechanical requirements,whether they be for a short mast which must be attached to a chimney, orfor the installation of a tower including the foundation.Many installations have failed because of winds or ice loads. Here is thebook which describes the many details necessary for consideration in orderto assure ample safety and a good installation from the top -most element ofthe antenna, even though it is 100 feet above the ground, to the groundconnection on the receiver terminal board.

VACUUM -TUBE VOLTMETERSThis book has been rewritten and enlarged. Commercial vacuum -tube volt-meters are fully described as well as the basic theory of these meters. Em-phasis is on application and theory.

SERVICING A -M, F -M, AND TV RECEIVERS(Replacing Servicing Superheterodynes)

Written in the easy -to -understand Rider style. Describes troubles usually en-countered and the way they can be cured. Unique circuits are also discussed.

THE OSCILLATOR AT WORKDescribes oscillator circuits used in a -m, f -m, and television receivers and alsothe test oscillators and generators used in the servicing of these receivers.Emphasis is placed on the test procedures required and commercial oscillatorsare discussed in detail.

Watch For Publication Dates And Further Details

and become acquainted, or that recog-nized hams be invited to address service-mens' associations so that they can hearabout the ways and means of curing tel-evision interference from ham stations.

To bring these comments to an end, letit be said that these two branches of theradio industry might do well to co-operatewith each other and cease fighting eachother. Day by day, the hams are tryingto do more and more to lick TVI. Dayby day, the servicemen should learn moreabout TVI. In the end, everybody, in-cluding the public, will be happier.

JOHN F. RIDER

CoverThe photograph on the cover shows two

WOR-TV engineers seated in WOR-TV'sNorth Bergen transmitter building at theequipment that enables them to controlthe picture and sound transmitted by

WOR-TV on Channel 9. The engineer atthe left is making an adjustment to thepicture quality at the operating transmit-ter control console. The engineer at thethe right is stationed at the "mixingdesk", which synchronizes picture andsound transmission. In the foreground isa sound desk for playing records or mak-ing announcements from the transmitter.Wall units in the background housetransmitting equipment.

RIDER MANUALS ',r a S[ºVICING

AdditionsYork Radio and Refrigeration Parts,

York, Pa., Almo Radio Company, Wil-mington, Del., and Belmont Radio Supply,Chicago, Ill., should have been included inthe Jobber List that was published in theDecember, 1949, issue of SuccEssrur. SER-VICING.

LIPS 'GN .LIYSK3dA "N "NtIOA M314

alli'd3DV.LSOd -s -n

'fl 9 '7 'd "I9S "3eS

WI?1H3HeZr

SSIn `Ohf18s3Il.ib'x

'IS I.QHdH LIBI.00 23IAIi3S

OlQtii3peenuaaano ebaiaod %anney

A N'CI xxOA M3N -IS TVNVO 09P'3%I "133HSI7g11d FI3QII1 '3 NHOI

mo:3