How to Service Electronic Organs Rad Io- Eléctronics HUGO GERN: BACK, Editor

How to Service Electronic Organs Rad io- Eléctronics HUGO GERN: BACK, Editor

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WHAT GRADUATES DO AN D SAY NEED FOR TECHNICIANS INCREASING Chief Engineer "I am Chief Engineer Fast Growing Field Offers Good Pay, Bright Future of Station KGCU in field is do. So now to into -TV. Mandan, N. D. I also Today's OPPORTUNITY Radio- Televi- and can plan get Radio have my own spare time sion. Over 125 million home Radios plus 30 Keep your job while training with N.R.I. You business servicing high million sets in cars and 40,000,000 Television learn at home in your spare time. N.R.I. is frequency two -way com- sets mean big money for trained Radio -TV oldest and largest home study Radio -TV School. munications systems." Technicians. More than 4,000 Radio and TV Our methods have proved successful for more R. BARNETT, Bis- Broadcasting stations offer interesting and im- than 40 years, provide practical experience. marck, North Dakota. portant positions for technicians, operators. Soon after enrolling, many N.R.I. students start Paid for Co'.or television, portable TV sets, Hi -Fi, other to earn $10, $15 a week extra in spare time Instruments developments assure future growth. fixing sets. Many open their own full time It's the trained man who gets ahead. The fellow Radio -TV shops after getting N.R.I. Diploma. "I am doing very well who uses his spare time to develop knowledge and Find out more. Mail Coupon. Cost is low, terms in spare time TV and Radio. Sometimes have skill gets the better job, drives a better car, lives easy; includes all equipment. Address: National three TV jobs waiting in a better home, is respected for what he knows Radio Institute, Dept.9H F, Washington 16, D.C. and also fix car Radios for garages. I paid for Send for instruments out of earn- MAIL COUPON NOW ings." G. F. SEAMAN, New York, N. Y. LESSON NATIONAL RADIO INSTITUTE Has Own and CATALOG Dept.9HF, Washington 16, D. C. Cateet TV Business Job ana Mail me Sample Lesson and 64 -Page Catalog, "We have an appliance Qppotlunilies FREE. (No Salesman will call. Please write plainly.) store with our Radio FREE Sot and TV servicing, and Name_ Age__ _ get TV repairs. During RADIp-TV my Army service, NRI VETERANS ItCHNICIANS Address. training helped get me a top rated job." W. M. Available under City Zone_ _ _State WEIDNER, Fairfax, G.I. Bills South Dakota. ACCREDITED MEMBER, NATIONAL HOME STUDY COUNCIL!

AUGUST, 1959 3

www.americanradiohistory.com AUGUST, 1959

. R 5O YEARS Of MORONIC PUBLISHING í I Radio -Electronics

Formerly RADIO -CRAFT Incorporating SHORT WAVE CRAFT TELEVISION NEWS RADIO & TELEVISION

EDITORIAL ON THE COVER 29 Lethal Radio Waves -Hugo Gernsback Istory on page 46) First transistorized TV fo AUDIO -HIGH FIDELITY reach the market, the Philco 30 Servicing Electronic Organs Jaski projection receiver has a -Tom picture optically equivalent 35 Finishing Your Him Fi Cabinet -Jeff Markell to a 12 -inch tube, is view- 38 I Like Audio Work -John A. Comstock able outdoors in bright day- 39 All About the Reflex Enclosure, Part VI -P. G. A. H. Voigt light. The projection tube is 41 New Discs and Tapes -Reviewed by Chester Santon seen between set and case. Color original by Philco Corp. TELEVISION 43 Picture- Quality Control -A. V. J. Martin 46 Transistor TV Portable (Cover Feature) -Allan R. Curll and Paul V. Simpson 50 Those Internal TV Ghosts -James A. McRoberts 52 TV Service Clinic -Conducted by Robert G. Middleton Hugo Gernsback Editor and Publisher

M. Harvey Gernsback WHAT'S NEW Editorial Director Fred Shunaman 54 Pictorial Reports of New Developments Managing Editor

Robert F. Scott ...._W2PWG, Technical Editor Larry Steckler RADIO Associate Editor

55 Converter Puts FM in Your Car -Larry Steckler I. Queen Editorial Associate 56 Transistors . . . Fact and Fiction, Part II -Louis E. Garner, Jr. Robert G. Middleton 58 Citizens' Band Converter -J. H. Thomas = Television Consuttant 68 ABC's of Mobile Radio, Part VII-Leo G. Sands Elizabeth Stalcup 74 Transistor Headphone Radio -Homer L. Davidson Production Manager Cathy Steckler Advertising Production

Wm. Lyon McLaughlin ELECTRONICS ...Tech. Illustration Director Sol Ehrlich 75 Should I Choose a Home Study Course ? -Benjamin W. Tallman Art Director 80 Diodes Can Oscillate -I. Queen Fred Neinast Staff Artist

Lee Robinson TEST INSTRUMENTS ....Director, Advertising Sales Jahn J. Lamson 86 Oscilloscope Comforts -T. J. Bopkins Eastern Sales Manager,. G. Aliquo 88 Measure Capacitance with a Vtvm -John L. Janning, W8QCN Cirailatian Manager 89 Many Sockets Speed Tube Checking-William Kelvin Adam J. Smith ....Director; Newsstand Sales Robert Fallath Promotion Manager 120 Books 110 Noteworthy Circuits 117 Business and People 103 On the Market 20 Correspondence 115 Patents 122 Literature 95 Technicians' News 101 New Tubes and Semi- 113 Technotes Average Paid Circulation conductors 108 Try This One Over 187,000 6 News Briefs 109 50 Years Ago

RADIO -ELECTRONICS is indexed in Applied Science & Technology Index (Formerly Industrial Arts Index)

RADIO-ELECTRON ICS, August, 1959, vol. XXX, No. R. Published monthly at Mt. Morris, 111., by Iternsbactc Publications, Inc. Second -class postage paid at Mt. Morris, III. Copyright 1959 by Gernsback Publications, Inc. A11 rights reserved under Universal, International and Pan -American Copyright Conventions. SUBSCRIPTION RATES: U.S., U.S. possessions and Canada, $4.00 for one year; $7.00 for two years; $10.00 for three years. Pan- American countries $5.00 for one year; $0.00 for two years; $13.00 for three years. All other countries $5.50 a year; $10.00 for two years; $14.511 for three years. SUBSCRIPTIONS: Address correspondence to Radio- Electronics, Subscription Dept., 154 West 14th St., New York 11, N.Y. When requesting a change of address, please furnish an address label from a recent issue. Allow one month for change of address. GERNSBACK PUBLICATIONS. INC. Executive, Editorial and Advertising Offices, 154 West 14th St., New York 11, N.Y. Telephone Algonquin 5 -7755. Hugo Gernsback, Chairman of the Board; M. Harvey Gernsback. l'resident; G. Alipuo, Secretary. BRANCH ADVERTISING OFFICES and FOREIGN AGENTS listed on page 123 POSTMASTER: If undeliverable, send Form 3579 to: RADIO -ELECTRONICS, 154 West 14th St., New York 11, N.Y. .Trademark registered U. S. Pat. Office.

4 RADIO -ELECTRONICS

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www.americanradiohistory.com -J J J NEWS BRIEFS J J J J J JJ J J J--i J J J J

TAPE CARTRIDGE PLAYERS for 3% inch - HYDROGEN ENTRY OXYGEN ENTRY per- second 4 -track tape are now on the Calendar of Events market. RCA has shipped production GASKET Hoosier Electronic Conference, Aug. 9- 12, French Lick Sheraton Resort Hotel, units of its first model, priced at $300. FACE PLATE French Lick, Ind. Bell Sound, selling standard tape decks National Ultrasonics Symposium, Aug. and recorders through audio compo- 17, San Francisco, Calif. nents dealers for several years, fol- Western Electronic Show and Conven- lowed suit with an announcement that tion, (WESCON), Aug. 18 -21, Cow Pal- ace, San Francisco, Calif. it will offer six models to play the slow - MEMBRANE German Radio TV & Phono Exposition, speed 4 -track cartridges. These models Aug. 14 -23, Frankfurt am Main, Ger- start with a simple tape deck minus many. electronics, for use with high -fidelity National Alliance of Television & Elec- amplifiers, range up through a unit ELECTRODES tronic Service Assocs. (NATESA) Con- vention, Aug 20-23, Congress Hotel, including complete electronics. Chicago. Meanwhile, Magnetic GAS CHAMBERS the Recording British Radio Show, Aug. 26 -Sept. 5, Industry Association (MRIA) said that Earls Court, London, England. its recent announcement of industry National Exhibition of Radio, Televi- agreement to push sales of 4- track, sion and Records, Sept. 10 -21, Exhibi- 71/2 reel -to -reel stereo tape would tion Park, Porte de Versailles, Paris, -inch, France. not be affected by RCA's finally market- High- Fidelity Music Show, Sept. 11 -13, ing the long- awaited magazine players. Hotel Pfister, Milwaukee, Wis. MRIA officials echoed Bell Sound's Heart of America Rep Conference, Sept. position that 4 -track tapes at 71/2 inches 12 -13, Excelsior Springs, Mo. will provide high -fidelity stereo whereas Upper Midwest Electronic Exposition, the slower -speed magazine tapes will Sept. 15 -17, Minneapolis Municipal provide tape for the mass market. VENTS (NORMALLY Auditorium, Minneapolis, Minn. CLOSED) High -Fidelity Show, Sept. 18 -20, Palmer CELL STRUCTURE House, Chicago, Ill. ELECTRICITY DIRECT FROM GAS is now Instrument- Automation Conference & a reality in a new "fuel cell" developed other (or oxygen in the air can be Exhibit, Sept. 21 -25, International Am- by G -E scientists which creates low - used). At one electrode, the hydrogen phitheatre, Chicago, Ill. voltage do directly from combining molecules break up into electrons and EIA Fall Conference, Sept. 22-24, Tray - Atlantic City, N. J. hydrogen and oxygen. The fuel cell, positively charged hydrogen. The elec- more Hotel, Conference on Non -Linear Magnetics according to Drs. W. Thomas Grubb trons travel through an external load and Magnetic Amplifiers, Sept. 23 -25, and Leonard W. Niedrach of the G -E circuit to the other electrode, thus Shoreham Hotel, Washington, D. C. research laboratory, consists of a round creating an electric current. The posi- High -Fidelity Music Show, Sept. 25 -27, plastic disc about 1/2 inch thick and 3 tively charged hydrogen moves through Hotel Sheraton, Rochester, N. Y. inches in diameter. Its hollow interior the membrane to the other electrode, National Symposium on Telemetering, Sept. 28 -30, Civic Auditorium & Whit- is divided into two chambers by a where it combines with oxygen and the comb Hotel, San Francisco, Calif. special plastic membrane, which has an electrons from the external circuit to Industrial Electronics Symposium, Sept. electrode in contact with each of its form water. The fuel cell generates 30-Oct. 1, Mellon Institute, Pittsburgh, sides (see diagram). Hydrogen is fed electricity by a chemical reaction. In Pa. into one chamber, and oxygen into the the present version, hydrogen and oxygen produce an electric current, with water as a byproduct. Current densities as high as 30 ma to the square centimeter have been achieved with an open -circuit voltage of approximately 1 volt per cell. Thermal efficiency of 60% has been reached. COLOR TV GAINS on all fronts this fall predicted in many quarters. RCA carried the ball almost alone for the past 2 years; now Admiral has announced a full color receiver line. All networks are planning increased color - casting. Leader in this effort appears to be NBC, with 169 affiliated color - equipped stations set. NBC's fall color schedule will be almost one -third heavier G -E's Leonard Neidrach (left) than last year's, with color every night, and Thomas 2 hours on Saturday daytime and in- Grubb with their creased sports coverage. CBS now has "fuel cell." (Continued on page 10) 6 RADIO -ELECTRONICS

www.americanradiohistory.com Men 11.55 READ THESE AMAZING FACTS ABOUT A MAN Are l' One of WHO COULD BE the men who could pre'are for a cob that Du, 4YS. RFA. L MONEY in TELEVISION RADIO ec tonics 'rit WM0/eiMeM ARE YOU PASSING UP THE PAYCHECK -THE SOLID FUTURE ONLY DeVRY OFFERS -THE REAL BREAK -YOU'VE ALWAYS DREAMED OF? ALL THESE FEATURES! Only DeVry Tech provides Training Movies to You meet them almost every day ... the men who want to advance NO make the basic principles of Electronics crys- out of humdrum, low -pay, or no-future jobs. Some are men who had PREVIOUS tal clear! DeVry's explanations and illustrations to quit school too soon; men just out of school with no idea of what to TECHNICAL are a pleasure to follow. Over 300 practical ex- EXPERIENCE do; or men looking far help in Elanning a better future. Yet, many periments with actual Electronic parts are included NEEDED to give you on-the -job type know -how. You even build of them could-can, if they're 17-55-train at home, in their spare your own test equipment. time, for an exciting career with real money and an inspiring future in the field of Electronic:. And the tragedy of it is they don't know it! EMPLOYMENT SERVICE They think they need an advancers education. or some special experi- The Industry knows the quality of DeVry training. ence, or a lot of money, to start -but what they need most is the That's why our Employment Service usually has will to win. Maybe you're a man like that. Well, here's great news! more demands for graduates than we can fill. Its not too late' Electronic. offers men like you, when trained, dozens We can also help you get started in your of different job opportunities guided missile control to run- own shop. -from ning your own radio -television service shop. Get the full story of the

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8 RADIO -ELECTRONICS

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p_ ..., Address

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www.americanradiohistory.com NEWS BRIEFS (Continued from p. 6) A QUARTER -CENTURY OF PRECISION KNOW -HOW IS YOURS IN 155 stations with color equipment; ABC 138. ARTIFICIAL VOICE for the 2,500 people P c 0 in the US who lose their own through surgical removal of the larynx QUALITY ELECTRON! each tom.. rt year is a small unit (1% x 314 inches) EQUIPMENT with variable pitch and self -contained ' power supply. Speech quality is far IN better than that of previous artificial KITM 14-it 2.7K 2N169-A TRANSDUCER ose FOR: MODEL B -10 MODEL S -55 ON- 1.5K electronic hobbyists Battery Eliminator Kit Wideband 5" Oscilloscope less than 0.3% ripple output response DC to 5 Mc OFF and amateur radio PITCH CONI Ell no external filters required push -pull V and H amplifiers SW Kit Net Price: $41.95 Kit 2N174 Net Price: $87.50 OUTPUT hi -fi custom building factory Wired: $49.50 Factory Wired: $139.50 250 K and service .35 680!1 I N 137 -A _ 200µf _a science education and osc schools 10V technical BATT 2N 188-A 510 A industrial testing and quality control MODEL T -60 MODEL C -20 Tube Checker Kit Res- Cap -Ratio Bridge Kit full free -point lever PACO is the only line of 10 mmfd to 2000 mid selector system test instrument r/2 ohm to 200 megs kits engi- Kit Net Price: $20.95 built -in roll chart Factory Wired: $31.50 Nit Net Price: $38.75 neered and produced Factory Wired: $54.50 under the auspices of a leading test equipment and meter manufacturer. and, you pay nothing extra for the convenience . MODEL T -65 of buying PACO kits di- MODEL G -30 Transistor and Crystal Diode rectly from your own RF Signal Generator Kit Tester Kit 160 Kc to 240 Mc in 8 bands tests bobo, gain, leakage, etc. local parts distributor. 120 Mc fundamental output tests both p -n -p and n -p -n types Kit Net Price: $28.50 Kit Net Price: $39.95 larynxes, though still a little buzzy COMPARE PACO against Factory Wired: $39.95 Factory Wired: $59.50 The unit is pressed against one's throat any other kits for per- and the pitch is varied by a finger pres- formance, appearance, sure. Volume is the same as a normal ruggedness, ease of op- conversational voice. eration and simplicity Transistors in a relaxation oscillator of generate large pulses sent to a power assembly and wiring. transistor which drives a transducer similar to an ordinary telephone re- COMPARE PACO's su- MODEL M-40 MODEL V -70 High Sensitivity V -0 -M Kit Vacuum Tube Voltmeter Kit ceiver. Pitch is varied between 100 and perbly detailed, step -by- 20,000 ohms /volt DC wide -range 200 cycles by a rheostat (range is set 10,000 ohms /volt AC peak -to -peak step instruction manuals Kit Net Price: $31.50 Kit Net Price: $31.50 for 200 -400 cycles for women users). and giant size wiring dia- Factory Wired: $37.50 Factory Wired: $47.50 Bell Laboratories scientists H. L. grams, against any you Barney and F. E. Haworth developed have ever seen. the device. (See also "Electronics Yelp f a the Mute to Speak," RADIO -ELEC- SEE HOW PACO sets an TRONICS, June, page 48.) entirely new standard in 3 TV STATIONS have left the air since electronic instrument kit our July report: design and kit assembly MODEL S -50 MODEL Z -80 5" Cathode Ray Oscilloscope Kit RF -AF Signal Tracer Kit KDPS -TV, Des Moines, Iowa 11 instruction. push -pull vertical and high gain RF and AF amplifier KULR, Kalispell, Mont, 9 horizontal amplifiers visual and audible indicator WNED -TV, Buffalo, N. Y 17 t Available and on display at Kit Net Price: $49.50 Kit Net Price: $29.50 leading electronic parts distributors. Factory Wired: $84.50 Factory Wired. $42.50 KDPS -TV and KULR, both educa- in Write for latest, complete catalog. tional, are calling summer recesses, KDPS -TV until Sept. 14 and KULR for 120 days. C.. t r C. t- Our new figures are 554 US operat- P r211111111.11115gt IAI fl F61 ing stations, including 467 vhf and 87 Electronics Co, Inc., MODEL SA -40 uhf. The temporary loss of KDPS -TV 40 -Watt Stereo Preamp -Amplifier COMING SOON! and KULR drops the noncommercial 70 -31 84th St., Glendale 27, L. I., N. Y. silicon diode, low impedance power supply MODEL ST -45 total to 41. Export: 458 e'way, N .Y. 13, U.S.A., - 14 controls for AM /FM Stereo Tuner Kit Canada: Atlas Radio Corp., Toronto 19. optimum flexibility Matching companion for the SA -40 FCC MARKS QUARTER CENTURY of A DIVISION OF Kit Net Price: $ 79.95 Factory Wired: $129.95 regulating communications through al- PREC /S /ONAPPARATUS CO., INC. most 2,500,000 radio authorizations. Of these 1,600,000 are commercial licenses such as marine, aviation, public safety, industrial and land transportation; P A C 0 185,000 are amateurs. (Continued on page 16) 10 RADIO -ELECTRONICS

www.americanradiohistory.com Opportunities Clectronics

Do you know how you can convert your Radar present electronics knowledge into a Guided Missiles profitable and interesting career in Broadcasting any of the fields listed here? Aeronautical Electronics Thousands of interesting well paid jobs in elec- Computers tronics must be filled. To fill such jobs, you need sound technical training. An FCC license Automation is convincing proof of technical skill. Send for Industrial Electronics the three Cleveland Institute booklets offered here. They explain how you can prepare for an Home Electronics interesting and profitable career in electronics. Mail the coupon today -no obligation.

Find out how modern technical training and a Government License (FCC) can lead to profitable employment in any branch of electronics.

good training doesn't cost -it pays! Send for these 3 FREE Booklets Cleveland Institute of Radio Electronics Desk RE -32A 4900 Euclid Ave. Accredited by Cleveland 3, Ohio

the National In what kind of work In what branch !.f Elec- Please send FREE Booklets prepared to help me are you now engaged? tropics are you inter- Home get ahead in Electronics. I have had training or Study ested? Council experience in Electronics as indicated below: Military Home Experimenting Radio -TV Servicing Name Age Manufacturing Telephone Address Company Amateur Radio City Zone.. ._.State _. Broadcasting Fi? Other RE-32A 1 AUGUST, 1959 11

www.americanradiohistory.com TV Technician Bing Longton says .. . "We Can't Gamble With Customer

Bing Longton, co -owner of Longton Bros. TV in Wyan- dotte, Michigan, has had an active interest in electronics since his childhood. A graduate of Detroit's Electronics Institute, Bing and his brother started their own TV sales and service business in 1948. In slightly more than 10 years, business has expanded greatly.

The Longton business philoso- phy has always been that every customer deserves the utmost in service. This, coupled with a keen interest in new developments which allow better service, has enabled Longton Bros. TV to become one of the most successful TV service organizations in the Detroit area.

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GEMS RMC DISCAPSâ FP ELECTROLYTICS 5 rugged, moistureproof, Mallory "Gem" Are a product of the world's largest The Mallory FP -the original 85`C. tubular capacitors in an easy -to -use producer of ceramic disc capacitors. capacitor -now has improved shock - dispenser that keeps your stock fresh Long the original equipment standard, resistant construction and leakproof and clean -easy to find -no more kinks Mallory RMC Discaps are now avail- seal. Its etched cathode construction - in lead wires. They're your best bet for able for replacement. They come in a standard in all FP's- assures hum -free outstanding service in buffer, by -pass handy á" x 5" file card package . . . performance. High ripple current rat- or coupling applications. easy to stock, simple to use. ings fit the toughest filter circuits. ®A registered trade mark of Radio Materials Company, a division of P. R. Mallory & Co. Int. 12 RADIO- ELECTRONICS

www.americanradiohistory.com Satisfaction ...We Use Mallory Components for Replacement"

"Customers demand quality repair serv- we can always depend on MALLORY." ice, and at Longton TV the customer is Whether you need capacitors, conking. We figure the best way to keep him trols, resistors, silicon rectifiers or bat- happy ... and protect our own profits, teries, you get the highest quality too ... is to prevent complaints before components at sensible prices. The they happen. So we give him the best in Mallory line is the widest in the industry, service and the best in replacement and Mallory "service -engineering" assures parts -that means MALLORY compo- you fewer call -backs and more satisfied nents. We've used them ever since we customers. See your Mallory distributor started in business, because we know for a full selection of the parts you need.

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AUGUST, 1959 13

www.americanradiohistory.com GET BEHIND THE SYLVANIA s2.Combination

America's biggest magazines deliver this business -building offer to over

4Q011 Wlll S\1CCe!.RMxlyioc' 100 million readers! QOPiW shirley m..,i,. 1r*>."0"4" On June 20th Sylvania launches the dramatic combination coupon offer appearing in Amer- or ar`rl ica's biggest weekly magazine, TV Guide, and ,dd't, America's biggest monthly magazine, Reader's t1o.' ..,. valu` Digest -plus Sunday and Parade newspaper to Ibr ,.5°;,;:' supplement magazines. Your Service shares the spotlight with top - quality Sylvania picture tubes and receiving tubes in a three -point program to make your customer's old TV set better than when it was new. Month after month, more set owners will be saving the $2.00 coupon. Many will attach it to the back of their TV set so it's there for you to see. You can identify yourself with this program by featuring Silver Screen 85 and Sylvania receiving tubes. Get behind the biggest, most practical, business -building offer ever made to the Service industry.

Look for this ad in these leading national magazines.

14 RADIO -ELECTRONICS

www.americanradiohistory.com ß FOR MONTHS. 'This OOD rJlllJlllj certificate llll16 /lll/ß or more s wo rt' ¡ Sylvania $2.00 against n comb; mall s receiving purchase of natty .. tubes To the Installed set owlet. S 8 when card Picture and the tube. Products carton Inc., Box 87 ani3 sma' Screen This tube(s) t 85 warrarr, coupe n void You if pro wil' receive Sylvania Electric Offer limited $2 to continental or res Motel. DO by return U S.A. and Cash value ma L N wail- 1 /20th of may be 'withdrawn 1 cent. without noiice. Coupon Offer f Sells your service and Sylvania receiving tubes in combination with every Silver screen 85 you install

Here's an action -packed offer that can add an average of $3.00 to $6.00 in receiving tube business every time you install a Silver Screen 85 picture tube: Sylvania urges your customers to have their receiving tubes checked to make sure they get full performance from their new Silver Screen 85. And, to emphasize the importance of replacing weak tubes, Sylvania offers to pay $2.00 toward the cost of Sylvania receiving tubes installed in combination with a Silver Screen 85. Your customers mail the $2.00 certificate directly to Sylvania with the picture -tube warranty card and receiving -tube carton end. Nothing for you to sign or send. The Sylvania coupon Stock up on Sylvania. Be prepared for taped to your customer's 'I V set means more receiving greater- than -ever consumer demand for t.ibe business and greater America's Number One picture tube and picture tube profits for you. receiving tubes. SYLVANIA Subsidiary of GENERAL GENERAL TELEPHONE & ELECTRONICS í7)

AUGUST, 1959 15

www.americanradiohistory.com New H.H. Scott NEWS BRIEFS (Continued from p. 10) There are now 3,300 AM broadcast stations on the air, 600 FM and 435 vhf -TV, 75 uhf -TV. There are also over 200 legal translator stations work- Stereo Amplifier has ing. Two -thirds of the world's receiving sets (150,000,000 FM and AM, 50,000,- 0(10 TV), are in the United States. features never before TRENDS IN TV SETS are beginning to be seen in the new 1960 lines. In addition to the renewed push on color from Ad- miral and RCA, the 23 -inch screen is set for at least three major lines. Ad- offered at $139.9'* miral, Sylvania and Hoffman. Zenith is promoting the 24 -inch tube, and RCA and others have said they'll stick with The new H.H. Scott 24 watt stereophonic amplifier, Model 222, 21 inches until they see which of the new larger sizes new -set buyers prefer. puts top quality within the reach of all. This new amplifier has many Admiral joined Philco in showing a transistor portable TV receiver, but, features never before available for less than $200. It is backed by unlike Philco, announced no plans for marketing such a set in the near future. H.H. Scott's fine reputation. Check the features below and you JAPANESE VACUUM TUBES join the see why you should build growing list of "Made in Japan" prod- your new stereo system around th ucts on the American market. A line of H.H. Scott Model 222. over 150 types of receiving tubes made by the Hitachi Co. is listed at about 25 under US prices. Another line made by the Nippon Electric Co. will sell at US prices through Channel - Master distributors. Already being imported in limited quantities are capacitors, resistors, hi -fi and other electronic equipment, in addition, of course, to widely sold transistor radios. PARAMETRIC AMPLIFIERS are beginning to be commercially available. These low - noise high -frequency devices (described in detail in February, RADIO -ELEC- TRONICS, page 78) are now being supplied by Motorola's Military Electronics Div. in models for 220 and 450 mc. INTERCONTINENTAL COMMUNICATION will be stepped up by the trans -Atlantic cable now being laid from Newfound- land to France. Two cables are being Equalization switch lets Separate Bass and Effective scratch filter Channel balance con- Master volume control you choose between Treble controls on improves performance trol adjusts for dif- adjusts volume of both put down by a ship which proceeds at RIAA compensation for each channel let you on older worn records ferent speaker effi- channels simultane- 8 miles an hour, paying out the 11/4 - monophonic and stereo adjust for differences and improves recep- ciencies and brings ously. Also functions as records; NARTB, for in room acoustics and tion on noisy radio channel volumes into automatic loudness inch cables over its stern. The cable tape different speaker sys- broadcasts. balance quickly and control whenever de- has electronic repeaters every 44 miles, tems. / easily. sired. and the sections of 250 miles each must Special switch posi- This position lets you Exclusive center - be spliced at sea during laying operations for accurate bal- play a monophonic channel output lets you ancing, for playing source such as an FM use your present amp- tions. The 2,400 -mile run will cost $40,- stereo, reverse stereo tuner or a tape re- lifier for 3- channel 000,000. and for using mono- corder through both stereo or for driving phonic records with power stiges and extension speakers. HUGO GERNSBACK AWARD your stereo pickup. speakers. Separate stereo tape - for 1959- recorder outputs. 60 to an electrical engineering student of outstanding ability and promise of SPECIFICATIONS: Dual 12 watt channels ; 0.3% IM dis- success in electronics was made to Pat- tortion; 0.8% harmonic distortion; frequency response 20 to 30,000 cps; extremely low hum level (- 80db); DC operated preamplifiers heaters; Inputs for rick John Marino of Elmhurst, N. Y. stereo or monophonic recorders, tuners, phono cartridges and tape heads. Mr. Marino will he a senior at New Phono sensitivity 3 mv. Sub -sonic rumble filter prevents overload from noisy changers or turntables. Price $139.95* York University, College of Engineer- ing, next September. He is working H.H. SCOTT INC. Dept. RE -8.111 Powdermill Road, Maynard, Mass. International Export: Telesco Corp., 36 W. 40th St., N.Y.C. during the summer as a junior engineer Insist on genuine H.H. Scott components at the Sylvania Research Laboratories. His interest in electronics stems from *West of Rockies .$1.4.7.35. Accessory case extra. training he received in the U.S. Navy, from which he was discharged as an electronics technician, 1st class in 1956. Later he worked as a technician in- specting military gear for the Arma SEND NOW FOR Rush me complete details on your new Model 2 ) ) and Corp. before your complete 1959 Hi Fi Guide & Catalog. Dept. RE -8 entering NYU. FREE HI -FI GUIDE Mr. Marino experiments on his own a good deal, most recently having con- AND CATALOG structed an unique nonvacuum triode Name (Continued on page 18) Address City State RADIO -ELECTRONICS

www.americanradiohistory.com What Does F.C.C. Mean To You?

course is designed specifically What is the F. C. C.? not the general practice.) The first class radio- The Grantham telephone examination consists of F. C. C. Ele- to prepare you to pass FCC examinations. All F. C. C. stands for Federal Communications ment IV. It is mostly technical covering ad- the instruction is presented with the FCC exami- Commission. This is an agency of the Federal vanced radiotelephone theory and basic tele- nations in mind. In every lesson test and pre - Government, created by Congress to regulate vision theory. This examination covers generally examination you are given constant practice in all wire and radio communication and radio and the same subject matter as the second class ex- answering FCC -type questions, presented in the television broadcasting in the United States. amination, but the questions are more difficult same manner as the questions you will have to and involve more mathematics. answer on your FCC examinations. What is an F. C. C. Operator License? The F. C. C. requires that only qualified per- Which License Qualifies for Which Jobs? sons be allowed to install, maintain, and operate The THIRD CLASS radiotelephone license is Why Choose Grantham Training? electronic communications equipment, including of value primarily in that it qualifies you to take The Grantham Communications Electronics radio and television broadcast transmitters. To the second class examination. The scope of Course is planned primarily to lead to an F.C.C. determine who is qualified to take on such re- authority covered by a third class license is license, but it does this by TEACHING elec- sponsibility, the F. C. C. gives technical exami- extremely limited. tronics. This course can prepare you quickly to nations. Operator licenses are awarded to those The SECOND CLASS radiotelephone license pass F. C. C. examinations because it presents who pass these examinations. There are different qualifies you to install, maintain, and operate the necessary principles of electronics in a types and classes of operator licenses, based on most all radiotelephone equipment except com- simple "easy to grasp" manner. Each new idea the type and difficulty of the examination passed. mercial broadcast station equipment. is tied in with familiar ideas. Each new principle guage. Different Types The FIRST CLASS radiotelephone license is presented first in simple, everyday lar What are the qualifies you to install, maintain, and operate Then after you understand the "what ant: why" of Operator Licenses? every type of radiotelephone equipment (except of a certain principle, you are taught the tech- The F. C. C. grants three different types (or amateur, of course) including all radio and tele- nical language associated with that ;principle. groups) of operator licenses-commercial radio - vision stations in the United States, and in its You learn more electronics in less time, because telePHONE, commercial radioteleGRAPH, and Territories and Possessions. This is the highest we make the subject easy and interesting. amateur. class of radiotelephone license available. COMMERCIAL RADIOTELEPHONE operator licenses are those required of technicians How Long Does it Take to Prepare Is the Grantham Course a "Memory Coarse "? and engineers responsible for the proper opera- for F. C. C. Exams? of equipment involved in the No doubt you've heard rumors about "mem- tion electronic The time required to prepare for FCC exami- ory courses" or "cram courses" offering "all the transmission of voice, music, or pictures. For de- who has an example, a person who installs or maintains two - nations naturally varies with the individual, exact FCC questions ". Ask anyone radio systems or radio and television pending on his background and aptitude. Grant- FCC license if the necessary material can be way mobile ham training prepares the student to pass FCC memorized. Even if you had the exact exam broadcast equipment must hold a radiotele- much more PHONE license. (A knowledge of Morse code is exams in a minimum of time. questions and answers, it would be required to such a license.) difficult to memorize this "meaningless' mate- NOT obtain In the Grantham correspondence course, the rial than to learn to understand the subject. COMMERCIAL RADIOTELEGRAPH opera- should prepare for his second tor licenses are those required of the operators average beginner Choose the school that teaches you to thoroughly working with communica- class radiotelephone license after from 200 to understand - choose Grantham Schaal of Elec- and maintenance men 250 hours of study. This same student should tronics. tions equipment which involves the use of Morse then prepare for his first class license in approxi- code. For example, a radio operator on board a 75 additional hours of study. merchant ship must hold a radioteleGRAPH mately In the Grantham resident course, the time Is the Grantham Course Merely a license. (The ability to send and receive Morse course and a normally required to complete the "Coaching Service "? is required to obtain such license.) get your license is as follows: AMATEUR operator licenses are those re- individuals offer a "coach- quired of radio hams"- people who are radio In the DAY course (5 days a week) you should Some schools and get your second class license at the end of the ing service" in FCC license preparation. The hobbyists and experimenters. (A knowledge of the service" method is Morse code is necessary to be a "ham ".) first 9 weeks of classes, and your first class weakness of "coaching license at the end of 3 additional weeks of that it presumes the student already has a know- What are the Different Classes of classes. This makes a total of 12 weeks (just a ledge of technical radio and approaches the the on a and answer" basis. On licenses? little less than 3 months) required to cover subject "question RadiotelePHONE whole course, from "scratch" through first class. the other hand, the Grantham course 'begins at in logical order Each type (or group) of license is divided into (3 nights a week) the beginning" and progresses different classes. There are three classes of radio- In the EVENING course from one point to another. Every subject is you should get your second class license at the emphasis is on telephone licenses, as follows: week of classes and your first covered simply and in detail. Tfie (1) Third Class Radiotelephone License. No end of the 15th making the subject easy to understand. With class license at the end of 5 additional weeks of test so you previous license or on- the-job experience is re- total of less than 5 months each lesson, you receive an FCC -type quired to qualify for the examination for this classes. This makes a can discover daily just which points Sou do not required to cover the whole course, from 'scratch" along. license. The examination consists of F.C.C. Ele- class, in the evening course. understand and clear them up as you go ments I and II covering radio laws, F.C.C. through first regulations, and basic operating practices. (2) Second Class Radiotelephone License. No HERE'S PROOF that Grantham Students prepare for F. C. C. examinations in a minimum of rime. Here on -the -job experience is required for this exami- is a list of a few of our recent graduates, the class of license they got, and how long it Sock them: nation. However, the applicant must have Weeks already passed examination Elements I and II. License St., Chambersburg, Pa. 1st 12 The second class radiotelephone examination Ron Taylor, 29 S. Franklin 15 consists of F. C. C. Element III. It is mostly Beni Moore, P.O. Box 169, Opp, Alabama 1st technical and covers basic radiotelephone theory Donald R. Titus, 270 Park Terrace, Hartford 6, Conn. 1st 12 (including electrical calculations), vacuum tubes, Robin O. Okinishi, P.O. Box 375, Hanapepe, Kauai, Hawaii 1st 12 Route Smithfield, N. C. 1st 9 transistors, amplifiers, oscillators, power supplies, Billy R. Kirby, #3, 1st 12 amplitude modulation, frequency modulation, J. H. Reeves, 10621 Ruthelen, Los Angeles 47, Calif. measuring instruments, transmitters, receivers, Donald H. Ford, Hyannis Rd. (Cape Cod), Barnstable, Mass. 1st 12 antennas and transmission lines, etc. James D. Hough, 400 S. Church St., East Troy, Wisc. 1st 12 (3) First Class Radiotelephone License. No on -the -job experience is required to qualify. for FOUR COMPLETE SCHOOLS this examination. However, the applicant must the entire country, Grantham Schools of Electronics I, II, To better serve our many students throughout have already passed examination Elements maintains four separate Divisions -- Hollywood, Calif.; Seattle, Wash.; Kansas City, Mo.; and Wash- and III. (If the applicant wishes, he may take in license preparation, either home study or is ington, D.C. --all offering the same courses F.C.C. all four elements at the same sitting, but this resident classes. For further details concerning F.C.C. licenses and our training, send for our FREE booklet, "Careers in Electronics ". Clip the coupon below and mail it to the School nearest you.

Get your First Class Commercial F.C.C. License Quickly MAIL TO SCHOOL NEAREST YOU by training at To: GRANTHAM SCHOOL OF ELECTRONICS

1505 N. Western 408 Marion 3123 Gillham Rd. 821.- 19th St., N.W. GRANTHAM HOLLYWOOD SEATTLE KANSAS CIT! WADDINGTON Gentlemen: Please send me your free booklet telling 'vnw T can OF ELECTRONICS get my commercial F.C.C. license quickly. I understand SCHOOL there is no obligation and no salesman will call.

1505 N. Western Ave. 408 Marion Street 3123 Gillham Road 821 19th Street, N.W. Naine Acte Hollywood 27, Calif. Seattle 4, Wash. Kansas City 9, Mo. Washington 6, D.C. (Phone: HO 7-7727) (Phone: MA 2-7227) (Phone: JE 1.6320) (Phone: ST 3-3614) Address

City State Resident Classes MAIL COUPON NOW -NO SALESMAN WILL CALL L Interested in: Home Study, 94M 17 AUGUST, 1 9 5 9

www.americanradiohistory.com NEWS BRIEFS (Continued) PICTURE POWER

BLONDER -TONGUE

B -24 which worked in water. This "planoir triode" produced frequency doubling and even a slight amount of gain. He POW- R is a member of the engineering frater- nities of Tau Beta Pi and Eta Kappa Nu, and also of the IRE and AIEE. Awarded each year by the faculty of BOOSTER the College of Electrical Engineering, the Hugo Gernsback Scholarship has a cash value of $1,000.

EDUCATIONAL TV now has a total of 4:3 stations on the air. Many of these program only 2 to 4 hours a day at present but their audiences are / expanding and programs improving. / The coordinating group for educational television, / ll # National Educational Tele- vision and Radio Center, recently moved f ! its main office from Ann Arbor, Mich., /' tl to New York City. It received a grant , of $5,000,000 from the Ford Founda- $2495 tion to strengthen educational TV, which bids fair to grow into a fourth network within a few years.

it's a powerful booster® FIRST STEP TO INTERCONTINENTAL TV was the sending of a movie over the trans -Atlantic telephone cable. It was ...or an amplified coupler! hailed as the first experimental transmission of "TV pictures" across the ocean. The British and Canadian provides sharp, clear TV pictures on Broadcasting networks cooperated with 1, 2 1 NBC to rush two 1- minute movies to the or more TV sets with only antenna US audience of NBC. The 180 feet of SE movie film was shot as Queen Eliza- `straight -thru' circuit provides up to 10 db beth left London to join President Ei- gain as a powerful one -set booster senhower in opening the St. Lawrence seaway. The film was processed. Then every `couple -two' circuit provides up to 5 db gain second frame was scanned by a method 0 00 0 e 001 developed by the BBC and NBC. Then (per set) as an amplified two -set coupler it was sent over the 4,500 -cycle intercontinental cable. Scanning and trans- ANT mission took about 3 hours. `straight -thru' circuit and B -T 4 -set coupler Although not quite true trans- Atlan- 0© eQM St 0.1 provide no -loss 4 -set distribution system tic television, the system is 100 times as fast as present facsimile techniques. Employs new frame -grid tube 6DJ8 new circuitry to achieve highest signal APACHES RAN FAST to FCC with first gain and "lower- than -cascode" noise factor. Provides full broadband ampli- reported application for vhf booster fication covering low and high VHF channels. May also be used as FM -TV station. The Jicarilla tribe of Dulce, coupler. Features "NO- STRIP" 300 ohm terminals for positive, electrical N. M., had its booster picking up and contact in seconds. Has "on /off" switch. rebroadcasting on channel 4 the pro- Improve TV reception today on 1, 2 or more TV sets with a single antenna. grams of KOB -TV, Albuquerque. The FCC replied that it's too early for Available at parts distributors. For details write RE -8 booster applications. Indians also asked BLONDER -TONGUE LABORATORIES, INC. if they could send a representative to 9 Ailing Street Newark 2, N. J. Washington for help with some of the In Canada: Telequipment Mfg. Co., Ltd., London, Ont. Export: Morhan Export Corp., N. Y. 13, N. Y. problems they've been running into with hi-fi components UHF converters master TV systems industrial TV cameras FM-AM radios monitoring and frequency control. END 18 RADIO -ELECTRONICS

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CITY ZONE STATE. -I---- MON ---4/MMIIMII---- - AUGUST, 1954 19

www.americanradiohistory.com Tung -Sol audio tubes 411111.4 dynamically balanced and twin -packed in matched pairs C orresponclenceI' by the manufacturer

POLARIZED PLUGS are usually placed in the center of the Dear Editor: stage, not at one side ... I suspect that "Capt. Graham" is Re "Polarized Plugs," on page 33 a booby trap, that of the editor your June issue: I remember that a wants to see who's paying at- while back one of the electronic maga- tention! zines [This one! -Editor] had an arti- W. C. WARE cle about soldering a paper clip around Chicago, Ill. the edge of one blade of an ordinary Dear attachment plug to make it wider. This Editor: fixes the plug so it can be inserted only In answer to Capt. Graham . . . one way. I tried it and it works fine. recording and playing stereo as he But don't forget to check with a neon suggests by spreading the orchestra in or other tester to make sure the wider two rooms . . would lose the third slot is the grounded one! Very impor- dimension which is the great value of tant! stereo. This is what is called depth. GEORGE HRISCHENKO And depth comes from using two or Maidstone, Ont. more microphones in the same room. A singer at stage right is picked up (The two -prong polarized plug has directly by the right microphone, and a other weaknesses. Many pieces of few micro seconds later by the left equipment have the switch in the microphone. These two signals, later ground lead, for example. In such cases, re- created by speakers spaced similarly, a set may be safe when turned on and 5881 For service in 6550 For service in gives us the depth. Obviously even more hot when turned off. For further de- channels would sound better. amplifiers of up to 50 amplifiers and commer- tails on two- and three -prong polarized watts. equipment RICHARD LASIUK cial audio of plugs and general set safety, see "Death up to 100 watts. Thorp, Wis. Rides the Hot Chassis," page 100, Octo- ber, 1957, RADIO -ELECTRONICS. -Editor) PRO -COOPER'S EARS you can come as close to Dear Editor: N oNowfaultless sound reproduc- MORE ON GRAHAM'S THEORY tion as the design and circuitry Dear Editor: George Cooper's excellent article on of your hi -fi equipment will I've long been curious Golden Ears could have been even as to the true stronger if the author had realized permit. Tung-Sol 5881 and 6550 identity of Mohammed Ulysses Fips, and beam -power amplifier tubes are but Capt. mentioned the fact that no music exists Graham's letter in your June which has audible dynamically balanced and fac- issue has finally let the out overtones above 9,408 cat of the cycles, as Dr. Fritz Kuttner pointed out tory- matched to very tight per- bag! Surely the redoubtable M. U. F. is formance limits to help you none in The High Fidelity Reader (edited by other than Capt. Graham! Roy Hoopes). achieve lowest distortion at all His suggestion that dead silence Tests showing hearing from 15,000 volume levels. should come from the speaker opposite the to 20,000 cycles refer to sound at the Use of Tung -Sol 5881 and singer's position on stage implies level of both the threshold of pain, not to 6550 tubes has long been asso- that speakers must be silent when music at actual listening levels. with of the singer is in the middle ciated amplifiers the (a condition NORMAN ARLINGTON very finest design. These tubes devoutely to be desired in the case of Gulfport, Fla. have always been produced to sonie singers!!), or that there be an closest possible tolerances with infinity of speakers used to match every cathode current ranges held to possible intermediate placement on 8AP4's ANYONE? an absolute minimum. stage. Dear Editor: Now, in twin -packed pairs, RICHARD A. WALL I wonder if any of your readers has they assure the hi -fi enthusiast Riverside, Calif. an 8AP4 cathode -ray tube in working and the commercial sound en- condition lying around his shop? Or an (There is a real Capt. R. F. Graham Arvin deflection yoke with the gineer of replacement tubes that whose numbers letter on page 18 of our June C -24283 in the junkbox? Drop me a will provide new standards of issue came to us unsolicited.- Editor) performance -a feature of card and I'll buy.... Thanks. special importance with the Dear Editor: WALTER A. KOEHLER newest amplifiers and loud- 1.31 Drive Captain Graham must have a tin ear. Stratford speakers, particularly binaural Houghton Lake 12, Mich. See your Does he always sit fifth row center in sound equipment. the concert hall? Or does he have only parts supplier. one ear? If he has two, let him alter- ATWATER KENTS AND PARTS Tung -Sol Electric Inc., nately cover and uncover one while Dear Editor: Newark 4, New Jersey. listening to his wife, to see that sound I have an Atwater Kent model 36, actually does appear at the other ear, serial 2606628, and a model 20, serial and must therefore be recorded at that 311801, both in top condition -the 20 volume and phase and reproduced in is in its carton and has never been TUN GSO L the corresponding speaker . . . Solists used. Can you tell me what tubes it 20 RADIO- ELECTRONICS

www.americanradiohistory.com SIGNAL INJECTION POINT-TO-POINT - DIRECT VIEWING

MODEL 1075 TELEVISION ANALYST

Solve Rough Sweep Output Problems New Technique Makes TV Servicing Easier, Faster, More Profitable NEW Model A107 Thousands of service technicians already save thousands of hours every day with the amazing DYNA- SWEEP B&K TELEVISION ANALYST. Enables you to inject CIRCUIT ANALYZER your own TV signal at any point and watch the resulting test pattern on the picture tube itself. Saves many hours of service work. Makes it quick and easy to isolate, pin -point, and Provides vertical and horizontal correct TV trouble in any stage throughout the sync and driving pulses that enable video, audio, r.f., i.f., sync, and sweep sections of you more easily and quickly to black & white and color television sets- including check out every stage in the sync intermittents. Makes external scope or wave -form and sweep sections of a televüsion interpretation unnecessary. Enables any serviceman receiver. to cut servicing time in half, service more TV sets in less time, really satisfy more customers, and make more money. Color generator provides Tracks down troubles in he horizontal and vertical output c rcuit both rainbow pattern and color bars. including defective output transformer and yoke; checks for shorted turns, leakage, opens, short circuits, and continuity. Includes unique MODEL 1075 TELEVISION ANALYST. Complete with standard high -voltage indication. Eliminates trial and error replacements. test pattern, white dot, white line, and color -bar slide transparencies, and one clear acetate. Net, $25995 Model A1O7 Dyna -Sweep. Companion unit for use only with B&K Model 1075 Television Analyst for driving source. See your B &K Distributor or Write for Bulletin ST24 -E Net, $49.95 Model 1070 Dyna- Sweep. Same os Model A107 Lut has B & K MANUFACTURING ;CO. its own horizontal and werti:al driving pulse, and is used inde- 3726 N. Southport Ave. Chicago 13, Illinois pendently of the Model 1075. Net, $69.95 Canada: Atlas Radio Corp., 50 Wingold, Toronto I 0, Ont. Export: Empire Exporters, 458 Broadway, New York! 3, U.S. A.

AUGUST, 1959 21

www.americanradiohistory.com CORRESPONDENCE (Continued)

uses, when these sets were made, and if they're worth anything as collectors' items? Also, I have several hundred parts for Atwater Kents of the 1920's, many in original cartons; coils, dials, tubes, tuning condensers, switches, controls, cases, hardware and power supplies. Also some metal -cased A -K's. Any market for these? JAMES STEGNER R.D. 1, Mount Zion Clearfield, Pa. (Mr. Stegner's query regarding the tubes has been answered. Do any of our readers know when the sets were built? Or want any of his Atwater Kent power supplies, parts or sets? -Editor.) SOLDERING NOTES Dear Editor: I have been trying to find time to comment on Mr. Darwin H. Harris' article "Notes on Soldering" which appeared on page 58 Of RADIO- ELECTRON- ICS, November, 1958. Most interesting was the writer's using his head and trying something different instead of following the time - honored rule of making the joint mechanically sound before soldering. Mr. Harris would be gratified to read with this an article titled "Reliable Soldered Con- nections Without Mechanical Joints" by J. Roy Smith, Head, Reliability and Standards Branch, US Navy Electronics Laboratory, San Diego, Calif. The article starts on page 143 of the Sep- tember, 1956, issue of "Electrical Manu- facturing." The article is a report on an ex- haustive investigation of soldered con- AUDIO AMPLIFIER KIT nections where pigtails were only poked through the hole of a lug or bent part Get your share of the hot market in converting monaural hi -fi way around a turret terminal - just enough to keep them from falling off. sets to popular stereo. Erie "PAC" Audio Amplifier Kits give The board wired up with a number of you a second profit on your assembly time. Embossed circuit components in this manner, poorly supported mechanically but well soldered, board and plug -in components require little assembly time to was put through all the military tests build this high-quality for vibration, shock, acceleration, heat, four-tube push-pull audio amplifier. humidity, etc., and not one soldered connection failed. However, some of the See your Erie Distributor for the heavy components like paper capacitors complete -in- one -box Erie "PAC" tore loose under the punishment, leaving their pigtails behind, still securely Kit. Also ask him to show you the soldered. new Erie single - element ceramic Then they tried the same test with the component pigtails laid across the stereo cartridge with the simplest tips of vertical wires and soldered with A construction and the highest - a bare minimum of solder. few joints broke loose but the majority held. Sev- fidelity characteristics. eral different grades of solder were also tried without noting very much of any difference. I too have learned quite a lot about For the name of your nearest Erie Distributor, write to: soldering in the 35 years which have passed since I wired my first 3 -tube set with acid -core solder. I was demon- strating it and just about had the name on the dotted line when it quit. I have ERIE Electronics Distributor Division never forgotten what a job it was to redo all those corroded connections. ERIE RESISTOR CORPORATION H. B. CONANT Erie, Pennsylvania Conant Laboratories END Lincoln, Neb.

22 RADIO -ELECTRONICS

www.americanradiohistory.com build this great new knight kit A PRODUCTOFALLIED RADIO stereo hi -fi amplifi ..save up to 50%

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tremendous value at only knight -kit 20 -watt stereo hi -fi amplifier Newest complete Stereo high -fidelity ampli- than 11/2 % distortion). Response, 20- 20,000 fier at an amazing low $44.50. Incomparable cps, ± 1.5 db. Hum and noise better than 444"only $4.45 down value: Includes two built -in preamps for 85 db below full output. Has four pairs of switch selects stereo inputs: magnetic cartridge, ceramic never before such performance... magnetic cartridges. Single stereo phono, tuner or auxiliary inputs, plus cartridge, tuner, auxiliary. RIAA equalized such quality... such styling stereo reverse on each; also switches mono- for stereo discs. Expertly designed push -pull so a price... at low phonic inputs to both amplifier channels. output circuitry. Beautiful custom -styled Bass and treble controls boost and atten- case, 41 x 1314 x 9 ". With case, tubes, all I dnre volume parts, wire, solder and instructions. Shpg. 6 fl III 4uu41!nrlh'14'hl'fi uate. Special clutch -type concentric I I!It1lU4rt N tl!111100 permits individual channel balanc- wt., 27 lbs. knight-kit control EXCLU SIVE ing, plus overall volume control. Total out- Model Y -773. Knight -Kit Stereo GUARANTEE put is 20 watts (10 watts per channel at less Amplifier, F.O.B. Chicago 54450 MONEY -BACK meets or ex- KNIGHT -KIT Every specifications, published any ceeds money. Buy see over 50 other fine write for catalog or we refund your must % knight -kits ... -KIT! Build it! It KNIGHT as claimed-or HI -FI KITS HOBBY KITS INSTRUMENT KITS perform exactly is refunded Stereo Amplifiers Short -Wave Radios VTVM Cap. Checker your money Stereo Preamp AC-DC Table Radios VOM's R/C Tester, etc. iil,I,t14V 4Q9.14` nnnndp Stereo Control Clock -Radio Tube Checkers 11Q¡q,ivr' QVYxL'VYVVSViiWil f!.Odí10,11iP1111rti Hi -Fi Tuners Radio- Intercom Oscilloscopes HAM KITS Hi -Fi Amplifiers Transistor Radios Signal Tracer Receiver ONLY ARE knight -kits Speaker Systems, Electronic Lab Kits Audio Generator Transmitter CONVENTE.. Ei. IEERED and others and many others Sweep Generator VFO, etc. foreasiestbuilding -no previous elec- EASY TERMS ON ORDERS AS LOW AS $20 tronic experience needed. "Conven- ience engineering" means special attention to every detail: resistors are carded and numbered for easy selec- FREE ALLIED RADIO, Dept. 159 -H9 -1 tion; parts and hardwareare packaged 100 N.Western Ave., Chicago 80, III. in clear plastic bags for quick identi- 1959 ALLIED is stripped and fication; wire pre -cut. CATALOG Ship Model Y -773 Knight -Kit Stereo Amplifier. color- coded; finally I4NIGHT -KIT $ enclosed. step -by -step instructions and wall - sized diagrams make assembly a mar- Send for this value -packed catalog I Send FREE ALLIED 1959 Catalog vel of simplicity. featuring the complete KNIGHT -KIT line, as well as the world's largest I Name from stocks of everything in Electronics. order Address

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www.americanradiohistory.com A Bell Telephone Laboratories Several hundred listeners, meeting in small groups several times a day for weeks at a time, are then asked to experiment in noise appraisal rate the effect of noise on transmission of the various simulated telephone calls. "The native Hollander wears wooden shoes." For the Bell System, the results of the study will become part of the over -all transmission "Nebraska has no seacoast." objectives. At Bell Laboratories, they will influence apparatus and systems "The daisy is a common wildflower." development work. As these syllables, words and sentences come in over Noise is a major distraction of modern day living. It the telephones, stand -ins for millions of Bell System sub- is also an enemy of the Bell System. In a telephone re- scribers rate them for clarity of reception. ceiver during a call, it might be power line hum, switching From these tests, Bell Telephone Laboratories engineers or thermal noise, or perhaps atmospheric static. Bell determine what is objectionable noise, and work to mini- Laboratories spends a great deal of time, effort and money mize it in telephone circuits. They begin by tape record- to keep this extraneous noise from becoming annoying ing background noise associated with working telephone and to assure you of a trouble -free connection. circuits. Test statements of appropriate length and content (such as those above) are read onto a second tape, BELL and both are fed onto the test circuit under carefully con- TELEPHONE LABORATORIES trolled conditions. A third tape, of normal room noise, is played through a loudspeaker in the test lab. World center of communications research and development 24 RADIO -ELECTRONICS

www.americanradiohistory.com OAW. n ROAN for ALL TV installation needs! LOOK TO THE FOREMOST NAME at a better price. Practically all ROHN IN THE COMPLETE LINE OF HOME TV, products are available in the finest of fin- AMATEUR AND COMMUNICATION ishes ... hot -dipped galvanizing! Rely on TOWERS, PLUS A COMPLETE LINE the dependable name for ALL your needs OF INSTALLATION NEEDS. -ROHN ... today one of the largest You'll find that the ROHN line is manufacturers of a complete line of this complete. It gives you better products type equipment. TOWERS

No. 25 The ROHN No. 25 tower is one of the finest ever designed ... a full 33% stronger and more durable than "similar sized" towers. This is achieved by amazing zig -zag cross bracing design combined with highest grade steel and heavy -duty steel side -rail tubing. This superior this tower strength means that Fold -over The No. 25, be installed self - can ordinarily as well os heavy-duty Na 40 to feet guyed supporting 50 or communication tower, con be to 200! It is truly the finest tow- converted into "fold -oer" er of its kind for home televi- towers for amateur use ... the sion reception. only tower of its kind. The., let No. 6 you work on the ground! This ROHN tower features the well -known "magic triangle ", Communications the cross -bracing construction / \I FIVE complete lines of commu- that is unequalled in strength nication towers are avo,! ble Also and durability. available to fulfill practically any need, self -supporting, or guyed to including a 130 foot -rue about 150 feet. heavy -duty commumcc +ion tower that is completely ;elf - sent on request! supporting and guyed models Complete communications catalog up to 600 feet!

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Get the full and complete catalog from ROHN Manufacturing Company your ROHN representative. I 16 limestone, Bellevue Peoria, Illinois Please send me literature on full line of ROHN products. ROHN Manufacturing Company Firm Name Title 116 LIMESTONE, BELLEVUE PEORIA, ILLINOIS Address

City State

AUGUST, 1959 25

www.americanradiohistory.com needle -point impedance ... low mass New ... freedom from hum and distortion ... output level ... ruggedness. Includes 4 plug -in equalizing networks. Another Developments fine Columbia audio component.

from 3N326 ... Electronics

New Semiconductor Lines Drawing on its experience 41) PALOMAR in NPN switching transistors and PNP power Silver Vision transistors, CBS Electronics now adds a comprehensive group of NPN power transistors for use in complementary circuits. Its line of NPN switching Premium or Budget TV Tubes transistors has been more than doubled A CBS original! Sell your customer to meet increasing demands by com- whichever he wants: premium-perform- puter manufacturers. ance CBS Silver Vision or budget-. Matched Pairs for Higher Fidelity priced CBS Palomar. Either is easy to sell Typical of premium -performance CBS because of top brand prestige. Either receiving tubes are these audio output stays sold because of top per- tubes. Their critical audio character- formance in its field. Recommend istics are matched to help minimize these dependable national -brand CBS picture tubes harmonic distortion in push -pull am- with confidence. .sNNG,aN. ... »wNhsOOK: plifiers. The 6BQ5, 6V6GT, 5881 and 6550 matched pairs reduce distortion even below that attainable by controls for balancing plate currents. transistor course.

COLCrMH1_A :: Pq¿SFEH4t í5 Revised Transistor Course arzn Girta40 and Technician's Handbook Expanded CBS Transistor Home - Study Course (still only $25.00) makes it easy to learn about transistors by making practical transistor devices from readily available parts. Opens up advancement opportunities. 1959 Technician's Handbook, designed for Ultrahigh- resolution C -R Tubes the technician, is compact, handy, New UHR tubes offer still another modern. Its 550 pages include re- addition to CBS industrial tubes . . . ceiving, picture, special tubes and most inclusive line in the industry. semiconductors ... only $1.85. See They can compress into 1/20 square both at your distributor's. Professional 55 Stereo Cartridge inch all detail on the face of a 21 -inch This is the professional's version of the picture tube. They make practical WATCH FOR MORE reliable products popular Columbia CD. Designed for many advanced military and indus- through Advanced- Engineering transcription turntables, it uses a trial applications requiring resolution CBS ELECTRONICS, Danvers, Massachusetts .5-mil diamond stylus, and features beyond the capabilities of the unaided Electronic manufacturing division of superior linearity ... separation .. . human eye. Columbia Broadcasting System, Inc.

26 RADIO -ELECTRONICS

www.americanradiohistory.com NEW STEREOPHONIC EQUIPMENT NEW AF-4 Complete Stereo Dual Amplifier (not illus.) provides clean 4W per channel or 8W output. Usual solid EICO contrac- tion & trouble -free design. Inputs for ceramic /crystal stereo pickups, AM -FM stereo, FM -Multi stereo; 6- position stereo /mono mode selector; clutch- concentric level & tone controls. 2'db of feedback around each power amplifier reduces distortion to 0.3% at normal listening levels with hi- efficiency speakers (Nerelco AD4877M or equivalent recommended). Kit 53895. Wired. $64.95. the HF85: Stereo Dual Preamplifier is a complete stereo control system in "low silhouette" design adaptable to any type of 'installation. Selects, preamplifier, controls any stereo source - tame, STEREO discs, broadcasts. Superb variable crossover, feedback tone ton- Pals driven by feedback amplifier pairs in each channel. 1listor- AND lion borders on unmeasurable even at high output levels.. Sep- experts arate to -level input in each channel for mag. phono, tape head, mike. Separate hi -level inputs for AM & FM tuners & FM Multiplex. M ONAURAL One each auxiliary A & B input in each channel. Inden-n :ent level, bass & treble controls in each channel may be aderated together with built -in clutch. Switched -in loudness comae- rsator. say... Function Selector permits hearing each stereo channel iidiudu- ally, and reversing them; also use of unit for stereo or monophonic play. Full -wave rectifier tube power supply. 5I2Ad7/ 60083, 1 -6X4. Works with any high -quality stereo power emptier Such as EICO HF86, or any 2 high quality mono power amplifiers such as EICO H114, HF22, HF30, HF35, HF50, HF60. "Extreme in HI -FI Wired flexibility . a bargain" - HI -Fl REVIEW. Kit $39.95. $64.95. Includes cover. 11186: Stereo Dual Power Amplifier for use with HF85 Arose or any good self -powered stereo preamp. Identical Williamson-type the best buys are push -pull EL84 power amplifiers, conservatively rated at 114W, may be operated in parallel to deliver 28W for non- sterec use. Either input can be made common for both amplifiers by Service Selector switch. Voltage amplifier & split -load phase inverter circuitry feature EICO- developed 12DW7 audio tube for sl:nifi- cantly better performance. Kit $43.95. Wired $74.95. HF81: Stereo Dual Amplifier -Preamplifier selects, ampl'Tie s & Seeds controls any stereo source - tape, discs, broadcasts-8. World- famois it thru self -contained dual (4W amplifiers to a pair of speakers. Monophonically: 28 watts for your speakers; complete stereo EICO advantages preamp. Ganged level controls, separate focus (balance) coe.trol, independent full -range bass & treble controls for each channel. guarantee your cDmplete satisfaction: Identical Williamson -type, push -pull EL84 power amplifier& excellent output transformers. "Service Selector" switch permits one preamp -control section to drive the internal power ampli- Advanced engineering Finest quality components fiers while other preamp- control section is left free to drive your existing external amplifier. "Excellent " - SATURDAY REVIEW; ''Beginne--- ested," easy step -by -step instructions HI -Fl MUSIC AT HOME. "Outstanding quality ... extremely versatile" -- RADIO & TV NEWS LAB -TESTED. Kit ;69.95. Wired LIFETIME service & calibration guarantee $109.95. Includes cover. IN STOCK - 2ompare, then take hone any EICO MONO PREAMPLIFIERS (stack 2 for STEREO) HF -65: superb new design. Inputs for tape head, mil rnpnone, equipment "off the shelf" -from 1S.00 neighbor- mag -phono cartridge & hi -level sources. IM distortion 0.04 -ri;ht m 2V out. Attractive "low silhouette" design. HF65A Kit hood EICO dealers. Wired $44.95. HF65 (with power supply) Kit $33.95. Wired S49.95. MONO POWER AMPLIFIERS (use 2 for STEREO) HF60 (60W), HF50 (50W), HF35 (35W), HF30 (30W), HF2T :2W), HF14 (14W): from Kit $23.50. Wired ;41.50. o MONO INTEGRATED AMPLIFIERS (use 2 for STEREO) v HF52 (50W), HF32 (30W), HF20 (20W), HF12 (12W): from Kit $34.95. Wired $57.95. SPEAKER SYSTEMS (use 2 for STEREO) C HFS2: Natural bass 30 -200 cps via slot -loaded 12 -ft. spit conical o bass horn. Middles & lower highs: front radiation fh::m 81/2" edge- damped cone. Distortionless spike- shaped super -tweeter radiates omni -directionally. Flat 45-20,000 cps, useful 30-40,000 Stereo Preamplifier i F&5 cps. 16 ohms. HWD 36 ", 151/4 ", 111 /2 ". "Eminently musical" - Holt, HIGH FIDELITY. "Fine for stereo " -MODERN HI -FI. Com- pletely factory -built: Mahogany or Walnut, $139.95.; Fionde, $144.95. FM Tuner HFT90 HFS1: Bookshelf Speaker System, complete with factory -built Tuner H1194 AM cabinet. Jensen 8" woofer, matching Jensen compression- driver exponential horn tweeter, Smooth clean bass; crisp extended highs. 70- 12,000 cps range. Capacity 25 w. 8 ohms. HWD 11" x 23" x 9 ". Wiring time 15 min. Price $39.95. LOS -1 Brass Tip Matching 14" Legs easily convert HFS -1 into attractive tonne- lette. All brackets & hardware provided. $3.95. Stereo Amplifier -Preamp FM TUNER HFT90: A superior stable tuner easy to ar,semble - HF81 no instruments needed. Prewired, prealigned, temperature -compensated "front end" is drift -free, eliminates need for AFC. Pre - wired exclusive precision eye- tronic" traveling tuning irslicator contracts at exact center of FM channels. Prealigned II coils. Sensitivity 6X that of other kit tuners: 1.5uv for 20db qwieting; 2.5uv for 30db quieting, full limiting from 25uv. IF Ea dwidth 260kc at 6db points. Frequency response 20- 20,000 CBS idb. 2 output jacks: cathode follower to amplifier, Multic'er output for FM Multiplex Stereo adapter; thus prevents obrrescence. Very low distortion. "One of the best buys in high fidelity kits" - AUDIOCRAFT. Kit $39.95 ". Wired $65.95 ". Cover S3.'=5, Bookshelf Matches HFT90. Selects "'Si,' -' wide Speaker System NEW AM TUNER HFT94: Monaural 9kc @ db) or weak -station narrow (20c - _Mr @ -3 Integrated Amp ifie s: HFS1 (20c - -3 50, 30, 20, and 12 Wett db) bandpass. Tuned RF stage for high selectivity & servitivity; (use 2 for Stereo) precision eye- tronic' tuning. Built -in ferrite loop, prealigned RF & IF coils. Sensitivity 3 uy @ 30% mod. for 1.0 V out, 20 S -Q kc whistle filter. -directional db /N. Very low noise & distortion. High 10 Omni Kit $39.95. Wired $69.95. Prices incl. Cover & F.E.T. Monaural Preamplifier: Speaker System HFS2 HF65, HF65A 36' H x 151/4" W x 111/2" 0 (stack 2 for Stereo: 1 BEFORE YOU BUY, COMPARE:

You may examine the complete EICO line at any of 1900 neighborhood EICO distributors coast to coast. equipment several times the Monaural Power Amplifiers: Compare critically with 60, 50, 35. 30, 22 and 14 -Watt EICO cost - then you judge. You'll see why the ex- use 2 for Stereo) perts recommend EICO, kit or wired, as your best buy. Stereo Power Amplifier HF86 EICO, 33 -00 NORTHERN BLVD., L. I.C. E. N. Y. Fill out coupon on other side for FREE CATALOG Over 1 MILLION EICO instruments in use throughout the world.

AUGUST, 1959 27

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28 RADIO -ELECTRONICS

www.americanradiohistory.com Radio - Electronics Hugo Gernsback, Editor LETHAL RADIO WAVES

... the Must Reappraise the New Ejects of Radio Waves .

LATELY, new and unexpected physiological radio- frequency of watchful waiting. Then he became drowsy. A minute or effects, which may add an entirely new phase to our so after that he became aroused, alert and somewhat knowledge of the electromagnetic spectrum, have been agitated, moving his head from side to side. discovered. This development may have a far -reaching "Then in another minute or more there appeared un- influence in many directions. mistakable signs of some impending disturbance in the vital As far back as 1953 we reported on this page the experi- centers of the monkey's brain, which were probably resonat- ments of Sidney I. Brody, Commander (MC), US Navy.* ing with these electromagnetic waves. His nose became red, For sake of completeness of the present report, we excerpt his skin was pallid, and an anxious look dominatec'. his eyes. only a few paragraphs here: "He grimaced and smacked his lips, his eyelids began to "Present -day radar beams represent peak pulsed power quiver and he developed a rapid, vertical motiox called a of a million watts or over, as compared to the 45,000 watts vertical nystagmus of the eyeballs, the pupils of v. hich were of a decade ago. widely dilated. His respirations became more and more "Commander Brody observed that the two frequency irregular, he began to salivate and suddenly was thrown spectra, the S or 10- centimeter and the X or 3- centimeter into a major convulsion a few seconds before his death, his bands, are now in current use. He stated that the effect on life having been extinguished like the snap of a light bulb." living organisms of the various frequencies of electro- In about 5 minutes, Dr. Bailey reported, the monkey un- magnetic waves in these bands are thought to be essentially expectedly died. About 20 other monkeys were similarly thermal in nature. It is not known so far whether there tested but the exposure was halted in the cases of about might be other than heat effects when living organisms are half before they died. Most survivors recovered, although exposed to these radiations. they originally showed signs of brain damage. "It has been noted that the 3- centimeter radiations used Dr. Bailey suggested that the molecules of the animal's today in radar equipment can produce high thermal effects. brain may have been destroyed when they "resonated" with The energy seems to he absorbed near the surface of the the radio frequency of the nearby transmitter. A similar skin. When the power output becomes sufficiently high or phenomenon occurs when certain sound waves shatter glass- if there has been long exposure to the radiation, the subject es when the audio note has the same fundamental frequency receives ample warning due to the high heat generated on as that of the glasses. He also commented on the effect of the body. It is therefore thought that the 3- centimeter radio waves under proper dosage in the treatment of brain radiations do not seem to constitute a hazard for the exposed disorders. personnel. However, on frequencies in the vicinity of 10- More recently, Dr. John Heller, of the New England centimeters the conditions change because the high tem- Institute for Medical Research, demonstrated that radio peratures in this case occur about 1 centimeter below the waves below 50 megacycles "shake up living cells" pro- surface in organs not cooled by the blood stream. Since foundly. the skin is not stimulated by this heat, the subject does not Until further physical facts about various radia- frequency perceive heat nor pain -he no longer has any warning. phenomena have been investigated more comprehensively, Therefore, the 10- centimeter radiations become dangerous. one thing seems certain to most physicists. There is no "Commander Brody observed that areas of the body deleterious effect of radio waves, unless the subject- possessing a poor blood supply have no effective temperature - whether live or inert -is in the immediate vicinity of the regulating mechanisms, as in the lens of the eye, the hollow transmitter. organs, the gall bladder, the urinary bladder and parts of Indeed, the effect may not be lethal even if a person is the gastrointestinal tract. These are potential danger points close to certain transmitters. Thus diathermy, the use of for the 10- centimeter radiations. high -frequency waves in the region of 100 megacycles "Rabbits exposed to constant power in a 3,000 -watt field (3 meters), to generate heat in the living tissue for for 75 seconds were killed, while a 30- second exposure therapeutic purposes has been known and used extensively produced death in 2 minutes. Instant death to a rat resulted since the 1920's. after only 22 seconds' irradiation at that power, and 10 We may be certain that other frequencies will be dis- seconds of a 4,000 -watt constant power output killed a covered that have as yet unknown beneficial therapeutic hamster soon after exposure. In these animal experiments, effects in the treatment of various diseases. high increases in body temperature produced heat paralysis So far, for instance, the millimeter frequencies down of the respiratory centers." into the optical region have not yet been extensively ex- Recently, Dr. Pearce Bailey, of the National Institute plored, chiefly because of the lack of sufficiently powerful of Neurological Diseases and Blindness at Bethesda, Md., transmitters. revealed a new "remarkable phenomenon," as he termed it. For military purposes, intensive work is now in progress A commercial 100 -watt radio transmitter, working at a to discover suitable frequencies with massive power which frequency of 388 mc, was used in Dr. Bailey's experiments. could be pin -pointed on missiles while in flight. The under- A Rhesus monkey was so fastened that his head was sur- lying thought here is that if a sufficiently powerful beam rounded by a cylindrical copper -screen cavity. This cavity of radio frequency could intercept an atomic missile while was fed at top center by a quarter -wave vertical probe, in flight, it could affect the molecular structure of the bomb, connected to the transmitter output. Thus nothing touched either by direct radio -frequency or thermal elect, or both, the monkey. Says Dr. Bailey: thus exploding the missile anywhere from 10 miles up. "The switch was turned on and during the first few This then would constitute a perfect anti -missile counter seconds the monkey did nothing other than sit in a pose (always presuming that such a beam, or beams, could sufficiently penetrate the heavy metal casing of the A- or H- bomb). Yet the idea is not as impossible as it may appear ° See editorial "Radar Hazards" in the August, 1953, issue of RADIO - ELECTI:ONICS. at the moment. -H. G. AUGUST, 1959 29

www.americanradiohistory.com II H

SERVICING ELECTRONIC ORGANS

Any good electronic technician can repair and tune an electronic organ -if he starts off in the right direction. A few simple facts point the way

By TOM JASKI

Baldwin A5 organ console and Deagan chimes.

THE service technician who feels business. The best attitude is to be for the work, this is the quickest way that a saturation point may have friendly but firm. Get there when the to find out. been reached for service work in customer expects you. Find the trouble. If you make an agreement with the his community may still find a Then fix it and run. It is important on dealer, get his assistance in obtaining huge market for his work in an un- home calls to make a precise date service manuals. Some organ companies crowded, well paid and interesting field. (time and day). Fixing organs can are reluctant to send out such manuals. I am speaking of maintaining electronic involve a good deal of noise, and you One, the Allen Co., gets downright organs. may be in the way if you arrive when stubborn about the matter. They insist For one who is accustomed to repair- a bridge party has started or right on factory- trained service technicians. ing audio equipment and tracing faults after the baby has been put to bed. The dealer can also give you the in complicated television receivers, the You may even have to make a second names of organ owners in the commu- electronic organ presents no special call. nity, something you will need for your difficulties. Organ circuits are all audio If the customer wishes the organ advertising campaign once you get types, and usually not very complicated. tuned, include a small additional charge. started seriously. Another useful group However, there are a lot of them in Tuning some models can be a tedious of people to get acquainted with is the each organ. and time -consuming job, a very simple local organists for the churches that Electronic organ service is strictly one on others. Work out an average use electronic organs. You can get their a home -call business. You can't very time for tuning over a period of months, names from city directories, telephone well pack organs in a truck and take and base your charge on your own directories and, if there is one, from them to the shop for repair, although experience. More about this later. the local branch of the American Guild this has been done with some of the To avoid wasting time, never let the of Organists. customer know you can play an organ, smaller models. What and where are they? Before you get into this, let me warn even if you are an accomplished organ- you against some of the pitfalls I ist. You might find yourself giving an There are a lot of electronic organs learned the hard way -by experience. impromptu organ lesson or demon- on the market. Offhand I can think of People who have bought an organ re- strating the capabilities of the instru- the Baldwin, Hammond, Conn (for- cently (within the past year and a half) ment. merly Consonata), Wurlitzer, Gulbrand- are usually unsure of themselves as If you are not now repairing organs, sen (transistorized), Minshall, Lowrey, far as the works of their instrument is the first step is to find out what organs Thomas, Kelley, Allen, Wells and concerned, and love to talk to someone are sold in your community, and who Compton organs and such semi -organs all about it. They the dealers are. Introduce yourself to as the Hammond and Wurlitzer chord who they think knows the can keep you talking for hours, if you them, and declare your intentions. Some organ, the old Novachord, and could cut down your may be only too happy to find someone piano- attached Solovox and Lowrey are willing. This the calls from eight or nine a day to maybe willing to repair and tune their instru- Organo. Then you may come across four or five, and you'll soon be out of ments. If they already have someone old Everett Orgatron, the forerunner RADIO -ELECTRONICS 30 www.americanradiohistory.com AUDIO -HIGH FIDELITY of the Wurlitzer combination reed electronic organs. You may have to deal with the Wurlitzer electronic piano, and such additions to organs as the Maas -Rowe chimes, the Zimbalstern (an electric bell ringing deal) and various other traps and attachments. Finally, some of the modern pipe - organ builders have been using electronic tone generators and amplifiers for the lowest notes. Some of the large Casavant organs built in California by Dick Stenger have electronic notes in the pedal base. The reason for this is economy. The most expensive pipes in a pipe organ are obviously the largest ones. More than 75% of the cost of a pipe organ are the pipes below middle C. By making the lowest of them electronic, a lot of money can be saved. The notes are so low that no one can The Hammond Chord Organ chassis distinguish properly built electronic swings down for easy servicing. pipes from the real thing anyway. Where can you find electronic organs? First of all in homes, where the great majority of them are. Next you'll find them in churches, funeral parlors, school and civic auditoriums, lodge halls, movie theaters, bars, restaurants, broadcast studios, and even on ocean liners, private yachts and in house trailers. I have seen them in hospitals, houseboats and national park lodges in various parts of the country. Large hotels may have several stored for The chassis of the small- occasions and department stores use er Baldwin organ, the shows. I dare say Orgasonic, contains all them during fashion the tone generators. you'll find some in unexpected places. Master oscillators and I once saw one being used in a railway power amplifiers are on waiting room during the Christmas the lower chassis. Speak- holidays. Wherever organs are being ers are self -contained. used you may have to go to repair them on the spot. There are no accurate statistics that I know of, but you can be certain that the electronic -organ market is growing by leaps and bounds. New organ companies are springing up all the time. Once bought, an organ is something that lasts, and is a perpetual potential opportunity for service work. There are hundreds of thousands in the homes of the country now. What tools are needed? The tools and instruments you use to do an efficient home -call repair job on hi -fi equipment will just about do for organ repair work, except for a few h'''11. _ I° RADIUS small you can make for your- LEAST 3 POUNDS) extras KEY WEIGHT HOLDING DOWN KEY PEDAL WEIGHT (AT self. At a minimum you should have a a portable tube checker (preferably a transconductance type), a vtvm or sensitive multimeter (100,000 ohms per volt) and the necessary hand tools. A portable scope with enough response to cover the audio range comfortably OFFSET TOOL WILL and with at least 100 -mv -per -inch CUT WITH HACKSAW BE HANDY is helpful, but not absolutely BLADE OR JEWELERS sensitivity SAW \ essential. Make sure you have long test leads on both scope and meter. An organ is a large instrument, and you may have to reach quite a way with the test prods. Use clips on the ends of your Fig. 1- Simple but useful tools you can make for organ repair work: a -key and pedal weights are better then jamming keys and pedals with pencil or screwdriver; b- contact adjusting tool. AUGUST, 1959 31

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TONE 290V on a key to hold it down. Wrap the cuits in the Lowrey (see Fig. OUTPUT 2). If weight in tape or cloth, preferably felt, your customers have many of these to avoid scratching the keys. Then make organs, by all means stock some of the NOT IN ALL GENERATORS one or two much heavier weights which parts. I used to bypass the printed .0 will sit on pedals (pedals are rounded circuits with conventional parts, when on top) and hold them down. This way necessary, but it is sometimes difficult you will not have to have someone hold to do. You may have to replace all the TO down keys for you when tuning or parts contained in the printed circuit. NEXT checking. After a while you will become familiar GEN Finally, you should have a set of two with the tricks the various organs play or three small tools like the ones a most often, and be able to reduce the telephone repairman uses to adjust load you carry on your calls. Even so, relay contacts. You need them for the all you need in a day can fit into a small car. 12ÁU7 same purpose, adjusting relay contacts or the contact arms of key and pedal What should you charge for a call? switches. I get a minimum of $10, with parts These small tools can be extra. This pays for 65V BIAS made from travel time and old screwdrivers. Use a hacksaw with costs. An electronic organ represents PRINTED -CKT COMPONENT PACKAGE a narrow blade to cut the slots (see an investment of from $1,000 to $65,000 Fig. 1). These just about complete the for some of the bigger church organs. Fig. 2- Printed circuit assembly used in list of tools you will need. If any organ The owner will be willing to pay reason- tone generator of Lowrey organ. Note ably well that some external resistors had to be requires special tools for service, the to protect his investment. used. These resistors are not used in all manual will tell you about them. Serv- Once you have built up confidence in generators. ice manuals, it goes without saying, your work, you may be able to contract are your most important tool. If you for regular monthly maintenance for leads, so both hands are free to make cannot get the data on some of the a fixed fee plus parts. Many churches adjustments. organs, try the series "Electronics and prefer this arrangement. There is noth- Unless you have perfect pitch (the Music" by Dorf, starting with the July ing quite so disturbing to the mood of ability to reproduce vocally any note 1950 issue of RADIO - ELECTRONICS, and a religious service as an organ conking upon request), you'd better carry a going well into 1952. Dorf gives a lot out in the middle of a hymn. If you tuning fork, either A (440 cycles) or of details about various organs on the accept such contracts, you will also he C (261 cycles). You'll need them for market at that time, but there are responsible for keeping the organ tuned. tuning. Alternatively, you might be several new types out now. Let me warn you that you may have able to use a pitch pipe such as violin- [All issues containing articles in the to work on Saturday nights and early ists and other musicians may use to series are out of print. However, most Sunday mornings, before the first tune their instruments. But make sure of the information in the articles will be church services start. Incidentally, the pitch pipe is a good one; accurate, found in Dorf's book Electronic Musical some mutual -assistance pact with a and well constructed so it stays on Instruments, Schober Organ Corp., pipe -organ builder and service tech- pitch. You might have to check a pitch 2248 Broadway, New York 24, N. Y. nician may well be advantageous for pipe occasionally. An audio oscillator -Editor] both. may sometimes help, but I seldom need Each make of organ has its own one when servicing organs. peculiarities. To begin with, you should What is in an organ? Carry a cloth or small blanket to carry at least two of each type of tube There isn't enough space to give you avoid scratching polished console sur- used in the organ you are about to a complete course on how to trouble- faces. You're supposed to leave the service. Then you'll need an assortment shoot the various organs. But I can organ in better shape than you found of capacitors, resistors and such things give you a general outline and some it. Finally the specials. Make two lead as fuses and pilot lamps. Some organs hints. or iron weights, narrow enough to put use special pa rts, like the printed cir- Most electronic organs, except for

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NOTE C D E F G A B C D E F G A B C D E F G A B C D E F G A B C D E F G A B C D E F G A B C D E F G A B C D E F G A B C

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60 4 -FOOT NOTES

60 8 -FOOT NOTES 60 16-FOOT NOTES

PIANO KEY BOARD Fig. 3 -The organ keyboard showing frequencies of the stops and notes. Each key may simultaneously connect 2 -, 4 -, 8- and 16 -foot notes to four separate buscs.

32 RADIO -ELECTRONICS

www.americanradiohistory.com AUDIO -HIGH FIDELITY the very large Miens, are self -contained. tions of organ pipes imitating instru- VIBRATO BUS The console has one or more keyboards ments. or manuals of 61 keys each, a set of On the Hammond a more direct sys- .0032 stop tabs for each manual and 32 tem is used. Mechanically driven (and FLUTE pedals, also with stop tabs. The stop never detuned) oscillators are connected OUTPUT tabs are used to select the tones desired in such a way that each key can obtain from each set of keys. Home organs one fundamental and up to seven har- .167 often have only 12 pedals and no selec- monics of that fundamental, arranged organs by drawbars. These drawbars are in STRING tion of stops for them. Chord OUTPUT effect volume controls. The complex .167_C11 have shorter manuals, two pedals (high IK 27 and low) and a set of chord buttons tones coming from the formant cir- whole in one or more truly 82051 56K which let the player sound a cuits are amplified .01 chord with the high pedal and its base high -quality amplifiers with very good .167 pedal. low- frequency response. The emphasis , note with the low i i f' have contacts is necessary because, to bring out the The keys and pedals GND BUS V Ì I Ì Ì Ì which connect certain tone oscillators 16 -foot low C, the amplifier and speaker I r 1 to a common bus and feed the signals system must be capable of producing Ì Ì Ì B+BUì on through formant circuits, where 32 cycles per second, without noticeable f I F l i F #J they are shaped into the desired timbre, 60 -cycle hum. L__J L__ then amplified for loudspeaker repro- If an organ note fails, you can 3 KEYS Fig. 4- Hammond Chord Organ three - duction. Most organs use frequency - localize the trouble rapidly. If all notes note oscillator. Each key connects to divider systems. They have 12 master of that designation fail, the master B -plus, but two insert a network in oscillators, one each for each note in oscillator is probably not functioning. cathode circuit to change frequency. the top octave of the organ, and dividers If only some of them fail, the lowest for the other 5 to 8 octaves. If an one not working may be the divider and servicing them is like servicing organ has only 5 octaves, for various which is out of whack. If the notes are other audio amplifiers. stops the tone generators must be fine down to a certain point and then If a whole stop refuses to work, you borrowed and only one set, usually the turn sour, a divider is out of step. You are dealing with trouble in the formant 4 -foot set, as it is called, will be com- can tell more things by just depressing circuits or in the tab -switch contacts. plete. the keys. If the top and lower notes of There are many special circuits in Fig. 3 shows the scale arrangement a chain are OK but one is missing in organs, but here we can do little more and the footage notation. This notation the middle, you can almost bet that you than mention them. In some chord is inherited from pipe organs, where are discovering key- contact trouble. organs, for example, the tones share the pipes are designated by their length. When enumerating instruments need- oscillators. Some tones, usually adja- As you can see, to have a complete set ed, we mentioned a transconductance cent ones, are so rarely used together of 16 -, 8 -, 4- and 2 -foot notes, an organ checker. As you know from TV prac- that the oscillators are designed to must have 97 tone generators (96 + C) . tice, a tube which checks OK on emis- produce two or three tones each, re- In some organs these are all individual sion may refuse to oscillate. Some organ ducing the number of oscillators tre- oscillators and, although they are oscillators are sufficiently critical so mendously (see Fig. 4). synchronized, each one must be tuned that tubes which are perfectly usable Organ tuning, electronic as well as individually. The Conn organ uses this as amplifiers are no longer usable as pipe organ, is done by starting with system. But if the divider system is oscillators. I have a basket full of one particular note, usually middle C. used, only 12 notes, the 12 master 6SN7 and 12AU7's which are no longer To tune this note you can use a tuning oscillators, need be tuned, and the any good for organ work. fork or a well calibrated audio oscil- others will follow -provided they re- The amplifiers are nothing unusual, lator. How this note is tuned depends main in step! If not, circuit values in except for their usually high quality, on the type of organ you are dealing the dividers must be changed, unless they have some adjustable component. The Minshall used to have a habit of getting out of step, and there wasn't any adjustment. The formant circuits mentioned earlier change the tones from the oscillators to sound like flutes, trumpets, clarinets and all other possible imita-

Above are the works of the Baldwin A5. Power amplifiers are mounted in the separate speaker cabinets.

(Left) Inside the Hammond Chord Organ the ingenious two- and three -note generators are on the top chassis. Chord generators are at the left, power supply at the bottom. The speakers are mounted in the console and the power amplifiers (two 6V6's) are in about the middle of the upper chassis. AUGUST, 1959 33

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CONTROL TUBES assume that all organ tuners are a strange breed who don't know what they are talking about. Special things you may encounter FROM V GENERATORS 35V TO AMPL might include the modern percussion iii circuits. Usually these are some form of sharp -cutoff circuit, operated by a FAST ATTACK (ALSO FAST DECAY rapidly rising bias WITH PERCUSSION ON) (see Fig. 5). The OFF rise of bias is controllable, giving the

ON 30V organist various effects to play with. CUTOFF Y 270 V Similarly a plucked effect is obtained Y50 V by a rapidly decaying bias suddenly SWITCH DIODE turning on the control circuit. A hangover circuit then usually provides a 37V 270 5V V continued tone for a fraction of a 30V second or more after the key is re- E )- + PLAYING CLAMP leased. The hangover KEY circuit is a feed- DIODE back circuit which 3._.----11- allows the tone to decay only slowly (relatively, that is). 5V RECT Service manuals will be explicit about these special circuits, and usually give an understandable explanation of the gQEXTRA WINDING ON PWR TRANS PROVIDES 30V UNGROUNDED DC SUPPLY function. Several good books give very Fig. 5- Simplified solo percussion circuit (percussion on) in Hammond Chord Organ detailed explanations of the circuitry of electronic organs. One of them, The with. In pipe organs one pipe in each The progression for tuning looks Electronic Musical Instrument rank would Manual be tuned individually. In like this: First C, then C + G, then by Allan Douglas, published by Pit- an electronic organ, it may be one G +D, then D +A, A +E, E +B, man, is the most useful oscillator when it comes all by itself, or it may be the B FK +C #, C # +G #, G1 D#, to studying the various special circuits master oscillator of an octave chain. A# + F, F + C. (If the organ such as formants, etc. Electronic An organ tone is usually a complex has individual oscillators, this tuning Organs by Robert L. Eby (Van Kampen waveform. It contains the fundamental procession must be followed all the way Press) gives details on the construc- and sometimes many harmonics. But up the keyboard.) tion of various organs. almost always a goodly percentage of Notice that this way you have actu- How I got into the organ business is second harmonic, which is twice the ally tuned 12 pairs, but each note of simple. I started, with good tools and frequency and thus one octave away the octave appears once as the funda- a good manual, and worked rather long from the fundamental. mental which is used to tune the third over the first few. I also didn't charge If you have an organ with individual harmonic against. Remember (if you very much. From then on, I gradually oscillators, such as the Conn, you might are not a musician) that if an organist became more skilled, charged a little think of tuning a note by playing it speaks to you about a fifth or a quint, more, spent much less time on the together with one an octave lower and in terms of frequency this means third organs, and started to make some finding a zero beat. But this is not easy harmonic. But don't tell the organist, profit. This may be the simplest way to because the lower note already contains he will not comprehend and will simply get into it. Try it out. Good luck. END a large percentage of the upper one, and you will have a hard time discovering when you are actually on zero beat. Now it happens that other notes are the same as a harmonic of the funda- NEXT MONTH mental, but a harmonic which is not so prominent in the original note. This is the third harmonic. For a C, the note 1 1 G is the third harmonic. Now in musical Multi- Impedance Transistor Amplifier terminology this is called a "fifth" simply because the two notes are five The serious audio worker will find this a very white keys apart. useful piece of apparatus in conducting tests and experiments. A single- transistor In an electronic organ, there is even amplifier, more it matches all impedances likely to be en- reason for using this system, for countered, both in the input and output circuits. often all the notes of one kind are synchronized, and changing the master oscillator automatically changes the rest of the chain. Now, however, 1 you Diagnose TV Faults By Eye tune C with G (its third harmonic), G with D, and so on all around until Another of A. V. J. Martin's series of all notes have been tuned. For you troubleshooting pictures that show actual come right back around the circle. The examples of defects, tell exactly what third harmonic of a note must, of causes the trouble and how to fix it. course, not show any beats with the fundamental; so you tune for zero beat. There is one exception to this system, ILVT Voltmeter or Converter and that is B. For it the proper key to use is not a white key five places away, Using one double -triode tube for both power but a black one, F. (This is because supply and meter tube, this instrument is a of the tempered scale -we do not come natural for the beginner, experimenter or stu- out with a whole number when we dent. Can be used with any low-range millia- divide the frequencies of the notes meter or your present low -impendance input by 12.) multimeter, giving it an input impedance of at least 10 megohms. 34 RADIO -ELECTRONICS

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YOUR HI -FI CABINET

Stop wondering about how you're going to put a professional finish on that unfinished cabinet -just By JEFF MARKELL keep reading

LT'S assume you've recently ac- cabinet, doors, drawers, lids, drop ing furniture. I f you do, the result will quired a cabinet for your hi -fi fronts, slides, hinges, catches and lid be appalling. gear. It may be a knock -down kit, supports are all fitted in place and are Don't forget that your final sanding an unpainted unit from a furni- working properly. should be with the finest paper you ture or department store, or perhaps one Take a look at it -isn't it pretty? can get. In any event not coarser than you've built yourself. Now the question Fine! Now tear it all apart! 2/0, preferably 4/0. The finer this last is, how to get that professional -looking Everything that can possibly be re- sanding is, the easier it is to get a finish that is the final touch on a well - moved comes off. That means doors, really good finish. And be sure you get done job. The answer is provided in drawers, lids, baffles, backs, control places like the edges and hacks of the paragraphs that follow, which must panels and all associated hardware -in doors, the undersides of lids, the insides be combined with some hours of your short, anything that is not glued down of player wells and the insides of record own time and effort. to stay. storage compartments. Anything that Assuming that you're not an expert can be seen at any time is important. furniture finisher (otherwise you'd have Ready to start sanding When you think you are through finished the cabinet long ago), let's When everything is stripped off, you sanding, inspect both visually and by consider the process a step at a time are ready to start sanding first the touch. Sometimes you can feel rough from start to finish, before beginning main case, then the various other parts. spots that you cannot see until after the actual work. Then, you can collect If you have handled your materials the finish has been applied. But then, the simple supplies and materials reasonably carefully when you built the it is too late. After you are satisfied needed and begin. cabinet, the chances are you will not that you've done a really goori sanding A really good finish requires the find any bad scratches or gouges in job, clean away all sanding dust and liberal use of a secret ingredient - the surfaces. But you will find a batch get ready to start applying fie finish. Work. This magic ingredient, combined of minor scratches. These are pretty The first step is either staining or with a modest amount of knowledge inevitable, but must be removed. bleaching. You stain when you want and manual skill, will give you a result Use a relatively fine sandpaper from to darken the color of the natural that is a source of lasting satisfaction. the very beginning -no coarser than wood; you bleach when you want to The excellence of your end product will No. 0 garnet paper. Your fine -surface lighten it. If you want to Ieave the be in direct proportion to the amount veneers are not very thick, and it will natural color of the wood al Dne, skip of time and effort you expend sanding, not take much sanding to go clear both operations and begin a _h filling. rubbing, steelwooling and polishing. through. All you want to get off are For the benefit of those who want to So don't waste any of those commodi- the scratches, not the veneer. Harder precolor their wood, these operations ties trying to think of ways to avoid woods like oak will stand slightly are discussed first since they must be having to apply them. All the possi- coarser papers than, say, mahogany done first. bilities have already been thought up or walnut. and tried by a lot of other fellows just Always sand in the same direction Using a stain as clever and just as lazy as you as the grain -never across the grain, A stain is a type of dye and must be and me. and wrap your sandpaper around a flat mixed with a liquid vehicle before it Now that the dark side of the picture sanding block when doing the large can be used for our purposes. There has been given its due, we can afford fiat areas. are three types in common use: water, to mention that some of the curse can If you have an acceptable sanding oil and alcohol stains. Each has certain be taken off by the proper use of machine available, it must be the type advantages and disadvantages. certain power tools, which often can that has a fiat head on which a piece of Water stain is the one most com- be rented if you don't happen to own ordinary sandpaper is mounted or be a monly used. It penetrates wee in most them. belt sander. The flat -head types usually woods, is easy to prepare and use, Probably the most important single have an orbital motion. They are OK goes on with good uniformity and is factor in producing a good final finish for preliminary sanding, but should be not excessively slow drying. There is on a piece of furniture is the manner followed by hand sanding with the one trouble with water stain -it tends in which the surface is prepared, before finest possible paper, preferably about to raise the grain of the wood a little, any lacquer, paint or varnish is applied. No. 4/0. A belt sander can be used for usually making it necessary to sand It's just not possible for the finish to both preliminary and final sanding, pro- the piece lightly after staining to re- be any better than the surface under- vided you obtain a belt with a fine move the "peach fuzz." neath it. enough grit for the final sanding. Even Oil stain does not have this fault. Let's assume now that your cabinet then, some areas cannot be reached It does not raise the grain, but neither is completely assembled, with all the with the belt. These have to be done does it penetrate as well as water stain. required parts present and in place. by hand. And, of course, curved parts Its penetration is particularly poor on For speaker cabinets, this means the like moldings, turnings and headings dense, course -pored woods such as oak, baffle board and back have been fitted, are out for the machine. And by the but it is all right on softer, closer -pored speaker hole cut, and any ports or horn way, don't put a sanding disk on your woods such as mahogany. Oil stain sections cut and fitted. In an equipment electric drill and try to use it for sand- takes longer to dry than water stain, AUGUST, 1959 35

www.americanradiohistory.com AUDIO -HIGH FIDELITY but it eliminates the defuzzing needed after water staining. In the highly resistant woods -dense coarse -pored wood like oak or with a high oil content like teak an alcohol stain is the best bet. It has the highest penetrating power of all and is the fastest drying. Because of this rapid drying, alcohol stain is more difficult to apply uniformly, but with a little practice this problem can be mastered. In staining, the first thing is to decide what color you want. Since a wide variety of prepared stains are available, the chances are that you will be able to find a satisfactory color Apply filler gener- without too much trouble. ously to wood, using A specific stain has a different effect a circular motion. on each type of wood to which you apply it. This is caused partly by the differences in the colors of the woods before staining, and partly by differences in the densities and pore struc- tures of the woods, which in turn affect the penetration of the stain. This now leaves you with the problem of finding out how stain X will affect your particular kind of wood. Simply apply some of the stain to scraps left over from the material you used to make your cabinet, and see what the result is. Ii it comes out too dark after it dries, thin out the stain and try again. If it is too light, go back and get a darker stain. Remember one other thing, however, in finalizing the color of your stain. Pad the filler into A piece of wood that has been stained pores by wiping appears only a shade lighter than one across the grain with that has been stained and lacquered. burlap or other So if you are in any doubt, put some coarse cloth. lacquer, shellac or varnish on a stained sample, and see what you get. This is the only way you can really see your final color in advance. As soon as you've settled on the color, the hardest I would avoid wherever possible. Bleach- lon of water. After the washdown, the part is done. The actual staining is ing is usually done to mahogany to get piece must be thoroughly dried. It may easy. a blond finish, but it seems that, with even need another light sanding. With water or alcohol stains, just all the excellent blond woods now avail- slap 'em on and let 'em dry. But be able, you should be able to find a Filling sure you give them enough drying time naturally blond wood to use, making If you have not done any precoloring, before you move on to filling. Water bleaching unnecessary. Bleaching does the finishing process starts here. If stain can be deceptive, particularly in not necessarily result in a uniform color you have, this is the second step. For humid weather when it may feel dry even when done correctly, and the filling, use a paste wood filler, mixed as even though it isn't. Under such con- process does not guarantee stable re- directed to a creamy consistency. ditions play safe and give it a little sults, since dark streaks may appear If you're wondering what filling fills, extra drying time. in a finish that originally did bleach it is the little tiny pores in the surface Oil staining is different, but still evenly. of the wood. If unfilled, they show up very simple. Your oil stain will be a Most bleaches consist of two com- in the final finish as innumerable little fairly thick, gooey mixture. Brush it pounds, applied to the wood one after pocks that are practically impossible on, wait 5 or 10 minutes, and then the other. They are standard mixtures, to eradicate. Filling is easier! There wipe off the excess with a rag, cotton available from finishing supply houses. are a few very fine -pored woods that do waste or a pad of dime -store cheese- The most common bleaching procedure not need filling- birch, maple, gum or cloth. The length of time you let an goes like this: You apply the first mix- beech -but walnut and mahogany need oil stain stand to penetrate has an ture, let it stand for 15 or 20 minutes, a good filler. So do oak, limba, Prima- effect on how dark the stain will be, and then apply the second. After that vera and most of the other woods you so do not work too large an area at let the whole thing dry thoroughly. At are likely to use. one time, and try to keep the standing the end of the first stage, the piece will Filler comes in various colors, so time equal on the various parts. An oil have lightened partially but you do naturally you use the color that most stain takes longer to dry (at least not see the full effect until after the nearly matches your wood. The filler overnight), than either of the other second mixture dries. when mixed is a fairly thick goo. two types, so be sure to take this into After a piece has been bleached (the Brush it on, let it set for a few minutes, account before moving on to filling. second mixture has dried), it must be and then wipe away the excess with thoroughly washed down to remove clean rags, waste or cheesecloth. Wipe to filler into Want to bleach if? excess bleaching chemicals. Do this with across the grain drive the a dilute solution of oxalic acid, acetic the pores. This is the only time in fin- Before telling you how to bleach I acid, or a dilute solution of vinegar ishing when you wipe or rub across the ought to state flatly that it is something (about 1 quart of white vinegar to 1 gal- grain. After excess filler has been 36 RADIO -ELECTRONICS

www.americanradiohistory.com AUDIO -HIGH FIDELITY will make up for the difference. Work rapidly because the lacquer dries quick - ly, and no not brush repeatedly over the same area, or you'll get Laps and streaks. When applying one coat over another, it is even more impor ant to work fast lest the solvent in tine second coat soften the first. This really makes a mess. Again, as with spraying, a bit of practice makes a world of difference. Stay away from pressure cans of lacquer for your finish coats -the lacquer is too thin for anything but touchup work. When applying fin- If you want to shy away from lac- ish, start new stroke on dry wood and quer, or if it sounds a bit too tricky brush toward the for your first try, use varnish. It is previous stroke. much slower drying so you have more working time, but also remember to give it plenty of drying time between coats, and you will end up with an excellent finish. If for some reason you use shellac, OK. But remember you do not get the durability of lacquer or varnish. Don't let water or alcoholic beverages stand on a shellac finish. Water turns shellac an opaque white, while alcohol just plain eats it away. After all, the solvent for shellac is denatured alcohol. In furniture finishing, a lot of thin coats are always better than one or two thick ones. They go on more smoothly, dry better and need less Sand -finish the rubbing. Usually, three coats are surface lightly. Just to build up a finish, but you enough to dull the enough sheen without cut- might conceivably have a condition that ting through the requires more. When in doubt., put on finish. another coat. It cannot do harm and it may help. Photos Grand Rapids Varnish Corp. Rub a finish If all you want is a plain gloss finish, you can stop after building up the coat wiped away, the piece should dry for bines the advantages of varnish and to final thickness, and eliminate the a minimum of 6 hours or, better yet, shellac, without the disadvantages of rubbing. You can even use a flat overnight. If the filler is not dry either. It has the durability of varnish lacquer or varnish for your last coat enough, it pulls out of the pores when combined with the rapid -drying proper- and get a fiat finish without rubbing. you start to apply the finish on top ties of shellac and, being a water -clear Either one is often adequate for large of it. liquid, it has less effect on color than built -in wall installations but, for free- either one. standing furniture to really look right, Sealing If you have spray equipment, practice it should be rubbed. Your sealer is really the first coat of with the gun on scraps to get used to Many people prefer a matte or satin the final finish. The only difference it before starting on the cabinet. The finish, others like a high gloss. For is that the sealer is going on over raw two most common defects in amateur either, the first step is the same. This wood and tends to be absorbed a good spraying, and for that matter even in consists of thoroughly rubbing all sur- deal more than later coats. Therefore, professional spraying, are "orange faces with a wet dry paper dipped in the sealer coat is about 50 %% thicker peel" and "runs." Orange peel is a rough a solution of soap and water to keep than what you will use afterward. surface texture caused by inadequate the paper from clogging. Minnesota Under a lacquer finish use a lacquer atomizing of the laquer in the gun, or Mining No. 400 A or equivalent is sealer. Under varnish or shellac fin- by holding the gun too far from the ideal. Your purpose is to remove all ishes, use shellac. After the sealer has work. Runs are caused by spraying minor irregularities left by the brush thoroughly dried, give it a light sand- too much lacquer on one area. The or spray. This method is for lacquer ing with the finest possible paper be- excess material forms driblets that run and varnish finishes only. Do not use fore proceeding to the final finish. down from the over -sprayed area. These water on a shellac finish. :Jse ground are unsightly and difficult to remove. pumice and oil. You can also use Final finish coats Another problem that sometimes pumice and either oil or water on In commercial finishing, the material arises in spraying is called blushing. lacquer and varnish if ycu'd rather. used for final finishing is either natural It is characterized by semi -opaque If you have trouble finding wet dry or synthetic lacquer applied with a milky areas on the surface and is abrasive paper, forget it and use spray gun. Varnish is much too slow generally caused by excessive humidity. pumice. in drying for commercial work, and If this happens, quit spraying and wait After the first rubbing, the final step shellac, although rapid- drying, is com- for a drier day. depends on whether you wait a satin paratively soft and leaves much to be If you do not have spraying facili- finish or a high gloss. For a satin desired in the matter of durability. ties, apply the lacquer with a brush. finish, go over everything with an Where possible, lacquer is the ma- You'll never get it on quite as smoothly extremely fine steel wool. Don't take terial for the home craftsman. It com- with a brush, but a bit more rubbing your wife's pot scouring wool from the

AUGUST , 1 9 5 9 37

www.americanradiohistory.com AUDIO -HIGH FIDELITY kitchen. It is not fine enough. Try to all, and for some reason was not pre- first waxing, use a good heavy hard find some 4/0. viously removed. These can often be wax as protection. For a high gloss, get some furniture filled by a procedure called "burning rubbing compound and rub until the in." To do this you need a shellac stick Oil finish gloss suits you. If you have trouble of the appropriate color for your finish. No discussion of finishing is complete finding the compound, it may be easier A small springy artist's palette knife, without a mention of the oil finish that to locate some rottenstone. If so, use and an alcohol lamp. Heat the knife has become so popular, particularly in that. Your local paint store, and some over the lamp, and touch it to the recent years on walnut. This type of hardware stores, can give you a lot shellac stick. The heated knife will melt finish results in an extremely matte of help in locating materials. a bit of shellac and pick it up. Use this surface that emphasizes the grain and material while soft to fill the dent. It figure in the wood and is particularly Touchup where needed hardens as it cools, so work quickly. beautiful on well figured woods. Knife it in as evenly as possible, then There are two ways of handling an Since this article deals with new smooth off with very fine sandpaper, oil finish. It is applied either direct work I shall mention touching up rather and polish. to the raw wood or over a filler. Where briefly and leave a more detailed dis- a filler is used, the procedure for filling cussion of this subject to a subsequent Reassembly is the same as previously described. article which will deal with touchup, I personally prefer an oil finish on the repair, and refinishing of old work. Your finish is now complete but raw wood, but it is strictly a matter In any event if you have done a before you apply a final polish and put of taste. Of course, presanding is reasonably careful job of finishing and the piece to use, you have to reassemble needed in this process. rubbing, the defects that you are likely all the parts you removed. With speaker The oil used for an oil finish is to find are minor. If you do find any enclosures this may mean merely a linseed and is applied hot to improve defects worthy of attention, they will baffle and a back, but equipment cab- its penetration. Apply hot linseed oil, probably be one of two kinds. You inets usually involve doors, drawers, let the piece stand for about 20 minutes, may find that here and there along a lids, control panels and who knows what wipe off the excess oil and let the piece corner or edge you have rubbed clean hardware. Work slowly and carefully dry overnight. This procedure should through the finish. This is not uncom- so you are sure you are getting every- be repeated from three to six times. mon and shows up most on dark fin- thing back exactly as it was. You do An oil finish should be reoiled about ishes as a light line along the edge not want to drop or mar any parts, now once a month for the first few months that has been rubbed through. This that they are finished! and then once in 6 months. light line is removed by touching it up After it's all back together, it's a Oil finishes are a bit darker than with a bit of your original stain, and good idea to give the whole thing a lacquer finishes to begin with, and then a bit of lacquer applied with a coat of hard wax as a protective darken somewhat with time. So do not fine artist's brush. measure before putting it into use. Do expect a newly oiled piece to quite The other defect you might find is not use one of the self-polishing liquids. match an old oiled one or a lacquered a dent here or there that was in the They do not have enough body. They one, even though they are all made wood before you did any finishing at are all right for later on but, for your from the same kind of wood. END

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I Like Audio Work By JOHN A. COMSTOCK IT was 9 am and my shop was open the tape you keep the head clean and now." And I was, as soon as I put the for business, as usual. The phones give it a longer useful life. I also told phone down. I grabbed the chassis and were quiet and no one was in the store. him that every time the abrasivelike reached for the speaker, but stopped That was my chance to get at some of oxide - coated tape passes through the when I remembered how the last time those piled -up items on the bench. The head, it grinds away minute particles I had one of these jobs I punctured the first was a Spartan -Collaro record of metal, which eventually results in speaker cone. To keep that from hap- changer. The motor on the unit was impaired sound reproduction. pening again I put the speaker, face really making a racket. With the motor down, into a paper bag and rolled up running, I started tapping it (the Printed- circuit capacitor the top to give me an easy to grab motor) on all sides with a screwdriver The next job was an amplifier that handle. Then I grabbed the bag, shoved handle. Within a few minutes, the used a printed -circuit board. It just the amplifier under my arm and was off racket was gone and normal quiet wouldn't work. A few circuit checks on the job. operation resumed. This works for revealed an open coupling capacitor. many of these units as motor bearings Now all I had to do was replace the Record static are self -aligning and usually seat when unit. But it was a single -ended job, After installing the unit and show- the motor is tapped. and I didn't have one of the proper ing the customer that everything was value in the shop. A few minutes time working properly, I was told that after Some free information and I came up with an answer. I took a record was played several times it Buzzzzz, from the front door as it a standard capacitor (the right volt- would start causing hissing, snapping opened (translates into "someone in age and capacitance values, of course) and crackling noises. I asked him to the store ") -and away from the bench and bent one of its leads over and show me, and he did. Close examina- to the counter to greet my first cus- down the outside of the capacitor's tion of the disc revealed the trouble - tomer of the day. He wanted a new body. Next I slipped a piece of spa- grit and dust in the record grooves. head for his tape recorder -would in- ghetti over the unit. It wasn't tight Nothing wrong with the player at all! stall it himself. Also wanted some infor- enough, but a couple of drops of service As I always do when this question mation. He couldn't understand why cement kept it in place. Then all I had comes up, I simply told her to wash her his old head showed wear so soon. A to do was solder it into the circuit. records with a sponge dipped in cool few questions revealed that the tape water to which a capful of mild liquid was run over the head all the time, Protect speaker cones detergent has been added. Then rinse even when rewinding. I suggested that The phone rang. "This is Mrs. and let the discs air -dry. Never did get he reroute the tape around the head Foster. When are you going to deliver a complaint of that type from her again, when rewinding and showed him how. my amplifier? You promised today." and she always calls me for any elec- I explained to him that by rerouting "I was just leaving for your house tronic repair in her home. END 38 RADIO -ELECTRONICS

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ALL ABOUT THE

Part VI -Damping can reduce irregularities in a speaker system's response curve. This is how it works

cloth By P. G. A. H. VOIGT CLOSELY WOVEN MATERIAL (HANDKERCHIEF) Fig. VI-1-With two small pieces of you can demonstrate the effect of different fabrics that might be used for damping: a- cotton handkerchief; b-piece window curtain. ATI damping takes up of sound energy. This seems ridic- ulous since a speaker is sup- OPEN -WEAVE MATERIAL (CURTAIN CLOTH) posed to produce energy. How- ever, few systems are uniformly efficient over the audio -frequency scale and artificial damping has the advantage that sometimes it can be used selectively. Selective damping is damping which is particularly effective in a certain frequency range or which affects one particular mode of vibra- a tion. Thus it makes possible individual control of specific resonances or selected parts of the scale. Assuming that the cabinet is well that within its fibers is required to built, the frequencies to watch are: produce the air penetration. The region near the upper peak in When a stationary wave occurs in a 6 the impedance curve. cabinet, regions with maximum pres- The region near the lower peak. sure variation and negligible velocity The region of maximum coil cur- are set up. Other regions, usually rent in the trough between the away, One way to increase the effectiveness spaced a quarter -wavelength to fix peaks. where the velocity is maximum but of many absorbing materials is Any peaks caused by internal are also set up. them with folds or corrugations set to pressure negligible, This way more air stationary waves and reflections. Maximum pressure or maximum veloc- form air pockets. Normal damping materials apply ity, thus determines which kind of fric- has to penetrate and merge during frictional losses to the sound waves to tional absorption can be used advan- each sound wave. turn the sound energy into inaudible tageously. Since frictional loss occurs every heat energy. There are two main ways half -cycle, high frequencies are affected in which these materials operate, and more than low ones. For example, while both can be used in the same cabinet Sound -absorbing materials a layer of thick carpet may absorb simultaneously. Carpets, felt and similar densely most of a 3,000 -cycle wave which strikes When an ornamental grille cloth is packed materials are often used to line it, absorption at 30 cycles is negligible. placed across the front of a speaker, the inside walls of cabinets and thus act So lining the walls is not much good the sound has to pass through the cloth. as sound energy absorbers in the high - when you want to damp low frequencies As the air particles move through, there pressure regions. However, some of and the technique mentioned first is some sound energy loss because of these materials may cause unexpected (reminiscent of the fishnet) is prefer- friction, and additional friction loss trouble later. able. The damping material is placed as air particles penetrate into and Moths have an uncanny knack of so the sound waves pass through it. emerge from the thread itself. finding wool anywhere in hi -fi equip- The dense materials previously dis- The first kind of motion reminds me ment and after a while they spread cussed are unsuitable for this. They of the way water passes through a to clothes, carpets and other things of might stop the flow almost completely, fishing net. The frictional loss depends value. Damping materials liable to dividing the enclosure into separate on the relative velocity of the air draw moths should therefore be avoided. compartments. Materials for absorbing through the obstacle, and ceases if Fiberglas is stocked by some hard- sound energy as the sound passes there is no relative motion. The motion ware dealers and is used for thermal through them have a much more open when the second kind of loss takes place insulation. It is often recommended and texture. reminds me of the way water penetrates moths find it rather indigestible. (Han- Stretch a single layer of cotton hand- a sponge. A difference of air pressure dle Fiberglas with care. Wear a pair kerchief across your mouth and between the air outside the thread and of leather gloves if possible.) blow (see Fig. VI 1 -a). The resist- AUGUST, 1959 39

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frequency than the vertical ones. So s-- damping by lining the side walls should be effective and make other complications unnecessary. Absorbent wall lining does little to affect the basic Q of the air cushion or speaker because of the low effectiveness of such a lining at the very low frequencies concerned. Other means should be used to cut down the Q at the frequencies of the two main impedance peaks when the highest possible efficiency there is not required. Damping the lower peak frequency diminishes the likelihood of speaker overrun at just that very low frequency where this is most likely to occur. Damping down the upper peak frequency diminishes one cause of boomy bass, and is particularly important if that frequency is in the speech boom region. PRESSURE VELOCITY Anything that impedes the free flow of air at the port also acts as a damp- Fig. VI -2- Pressure and velocity distribution with a vertical stationary wave ing agent and can be used to reduce the of two half -wavelengths. Q of the air system. Used at the port, it affects ance can be felt easily. Now try again now.) Omitting the middle layer avoids the series resonance (lower with a piece of window curtain. You complications. At the top and bottom peak) directly at the region of maximum flow while will notice a great difference. Closely levels, complete layers can be used the parallel resonance woven textiles are even more resistant safely without dividing is affected to a lesser extent. One or the box. The more layers than the handkerchief. Each causes end layers are shown in the diagram as of burlap (sackcloth) some energy loss when air passes shaded regions. across the port will do quite well. through it, but the more closely woven The curve at the right of the box Special damping systems the material, the greater the resistance. shows the velocity distribution of the Thus, the desired amount of damping vertical stationary wave and the arrows Much ingenuity has been expended can be obtained by selecting a suitable on the right point at the two maximum in producing special arrangements. For material. There is plenty of scope for velocity levels. Inside the cabinet the example, Goodmans industries of Brit- experiment.' levels are shown as dashed lines. Flow ain, who have made a study of the Materials that are intended to act on type absorption will be most effective problem, have produced an "Acous- sound as it flows through them have if suitable materials are placed at tic Resistance Unit "' arranged to fit to be positioned (conveniently on those (dashed) levels. Burlap (sack- into the port. This contains damping frames) across the sound path. If cloth) is inexpensive and quite suit- material well supported within a rec- vertical, these materials should be able. A layer of such tangular wood frame whose dimensions material attached have stretched, if they hang limp they may to a frame could be used at either or been worked out very carefully. move with the sound, reducing the rela- both of these levels. The question of support is important, tive velocity and, in turn, the amount of Thus, in practice, we can absorb for, if the damping material "flaps damping. Materials which act as damp- energy from that particular stationary about" with the sound wave, the air ing agents when sound flows through wave at four levels. (At the two won't flow through the material in the inter- way intended them are usually too light to act as ab- mediate levels where there is maximum and the proper frictional sorbers in the pressure regions. A layer relative velocity, by flow friction, and absorption of energy will not take place. of handkerchief has a negligible effect, at the highest and lowest levels where Damping at the speaker opening is also possible. If is covered when compared with a 1 -inch layer of the pressure peaks, by penetration fric- it with suit- Fiberglas, for lining the pressure tion.) With appropriate materials, able damping material, a useful reduc- regions along the walls of a cabinet. energy can be absorbed at all four levels tion in speaker Q can be obtained easily. Thus, the two kinds of sound absorp- simultaneously. The results could, however, be disas- tion require quite distinct techniques, Another vertical stationary wave, but 'E. J. Jordan, Wireless World, January and and this permits a useful amount of of half the previous wavelength, would February, 1956. juggling. form pressure nodes at the levels of the dashed lines where we had max- How to apply damping imum flow. So that wave would not be Suppose we have a box baffle and affected very much by any light mate- want to absorb the vertical stationary rial just there. At the top and bottom, wave corresponding to one complete however, the thick layers would absorb wavelength. The box is shown in Fig. and, since at half the wavelength we VI -2. The vertical sine wave at the have double the frequency, they would left of the box shows the pressure dis- absorb more effectively than at the tribution, and the three arrows on the lower wavelength. left point to the maximum -pressure As lateral stationary waves do not regions. Densely woven thick materials flow through the horizontal intermediate at those three levels would absorb some layers, they are not affected appre- of the pressure energy but, if placed ciably by these. Layers stretched par- at all three levels, the cabinet would, in allel with the sides would serve. If the effect, be divided into two parts by the cabinet proportions are approximately middle layer. (This may or may not those discussed in the article on box be desirable but does not concern us baffiles (32 x 20 x 12% inches) (see "A Box For Your Speaker," RADIO - Fig. VI Damping material over rear 'D. E. L. Shorter in Wireless World (November ELECTRONICS, -3- and December, 1950) describes the method used January, 1959), the lat- of speaker damps parallel resonance by the BBC. eral stationary waves will be of higher without affecting direct highs. 40 RADIO -ELECTRONICS

www.americanradiohistory.com AUDIO -HIGH FIDELITY trous, as even one layer of some grille cloths can cut down the high frequencies from the speaker. The loss with enough layers to affect the low frequency of the parallel resonance (upper peak) might well be fantastic. By putting the damping material behind the speaker instead, the direct highs are not affected, but the parallel resonance is damped just as effectively. A simple way is to stick one or more layers of closely woven textile onto the speaker basket so as to cover the open- new nisrt ings. Another way is to cover the hack. The photo (Fig. VI 3) shows how I did this during an experiment.' The Reviewed by textile was fixed at its edge by tacking it to the wood surface around the Chester Santon wire and speaker and in the middle by a Station WQXR TAPES bound around the magnet. New York City STEREO and MONO

close STEREO has stimulated a reappraisal of able to work soloists at distances as placement at recording sessions. 10 feet. With proper acoustics, the i al element microphone even The trend is toward closer miking. The distance of space is maintained at that dis'ance formerly required between microphone and per- during the scenes featuring the ful: vocal en- former in monophonic work for realistic illusion semble. of space can be reduced in stereo recording and BEETHOVEN: Symphony No. 9 "Choral" still provide a more spacious aural environment. Otto Klemperer conducting soloists, chorus and A close mike placement has always offered Philharmonia Orchestra practical advantages. Is there an older trick in Angel Stereo Records (2) S -3577 the business than a lower volume setting at the None of the complaints voiced in last month's recording console to hold down tube noise and review of Decca's stereo Beethoven Ninth apply distortion all along the line? In the hall itself, to the Klemperer version now available in direct waves of sound still have more musical stereo. The first movement occupies all of side meaning to a recording microphone than do their one and the second and third movements share reflected relatives bouncing off the walls. Several side two, thereby avoiding the complications records reviewed this month put these factors fostered by crowding in the Decca version. The to good use. other points of importance, the rerorded level and signal -to -noise ratio, no longer present the RACHMANINOFF: Piano Concerto No. 3 problems Angel has known in the past. Having Van Cliburn, Pianist of the Air waited this long before releasing this important Kiril Kondrashin conducting Symphony now RCA Victor Stereo Record LSC -2355 performance of Beethoven's Ninth. Angel is to offer a towering work in competitive Taped May 19, 1955. during the course of a able sound. A more detailed analysis leading to a Carnegie Hall performance, this recording pre- versions will in career of final choice among existing stereo serves an interesting moment the s its new phenomenon. Van have to wait until Columbia is,' the music world's current performance of the '. it b. At the It offers the historian an early sequence Bruno Walter Cliburn. moment, Angel has the lead. in the trajectory of a blazing comet in the concert field. The trail of the Cliburn legend on Rashomon records is still nebulous. We may in time wit- Laurence Rosenthal conducting instrumental a second Cliburn release of this particular ensemble ness Carlton Stereo Record STLPX 5000 concerto in an interpretation of greater maturity of the stereo miking is Looking for a stereo record that s different? and poise. The proximity Rash- ideal for the small -scaled concept of the work Try this music from the Broadway play and orchestra. The wide omon which deals with the Japan c,) a thousand set forth by the pianist score, dynamic range offers maximum realism at aver - years ago. In composing the original a *tide variety Fig. VI effect of damping on volume on a playback system that has an Laurence Rosenthal drew upon 4 -The a.,e used the two impedance peaks of reflex en- exceptionally low percentage of hum. of Oriental music although the instruments closures. are found at many points of the globe. New TCHAIKOVSKY: Ballet Suites (Swan Lake, and different stereo vistas are c-reated with Sleeping Beauty) imaginative use of the samisen (a three -string conducting Virtuoso Symphony shows Arthur Winograd Japanese instrument), Balinese and Burmese The solid line in Fig. VI 4 the of London gongs, Indian ankle -bells, Chinese wood -block impedance curve for a 6.4- cubic -foot Audio Fidelity Stereo Record FCS- 50,010 from Tibet, of ballet drum and other exotic instruments You can't go wrong in this pair Nigeria, Turkey and South America. Out of this cabinet (without any textile damping) scores. The performances have a professional in conjunction with a 10 -inch speaker sheen and the engineering is meticulous in every having a free air resonance at 35 cycles. detail. Exceptionally wide -range response merits Fitting four layers of textile across expensive amplification. This record has low -end energy found in very few stereo discs available the back of the speaker as shown in the today. It may prove to be excessive in the case photo brought the impedance peaks of bass reflex enclosures of insufficient thickness down to the level shown by the dashed and bracing. Bass response is smooth and flaw- less on systems free of peaks down to 50 cycles Jtaáatxa line in Fig. VI 4. There was no special per second. Winograd doesn't fuss with the music damping at the port nor was there any and the British musicians, particularly the wind &uttcrrl internal damping while these curves players, turn in a fine performance. Sounds like multiple miking at close range. fENATA were being taken. As you can see, both 'EBALDi the series and the parallel peak are PUCCINI: Madama Butterfly Tullio Serafin conducting Chorus and Orchestra ufterfly reduced very effectively. of Accademia di Santa Cecilia, Rome Next month we will discuss variable London Stereo Records (4) OSA -1406 electromagnetic damping and how put- No record collection may be considered complete without this most melodious of operas. The ting the enclosure in a corner of a room better your equipment, the more emphatic will affects results. TO BE CONTINUED be your preference for the sound of the latest London version starring Renata Tebaldi. This n am indebted to Mr. O. C. Schwartz trading album offers powerful evidence in favor of close as America] Radio & T.V. Supply Co. of Toronto, miking technique. Puccini's music flows at a for the use of lab facilities to obtain the experi- of Verdi or mental results shown in Fig. VI -4 and the photo more comfortable volume than that of Fig. VI -3. Wagner. Accordingly, London's engineers were AUGUST, 1959 41

www.americanradiohistory.com AUDIO -HIGH FIDELITY percussive Tower of Babel emerges a fresh being pressed and distributed in America by is the dubbed -in sound of cattle, wagons and evocation of ancient Japan. The sound is super- Decca Records. Decca, for some time, has been horsemen heard at the beginning of some of the latively clean and the vivid use of stereo affords issuing Deutsche Grammophon performances in songs. Best of all, the full impact of voices terrific opportunity to demonstrate the new this country under its own label. This new ar- is conveyed without recourse to added echo or medium. rangement will make available to American wild boost in the bass curve. discophiles a wider selection of German recordings. These always have been interesting prod- Note: Records below are 12 -inch mono LP and play ucts from the standpoint of performance and back with RIAA curve unless otherwise indicated. BLOCH: Axa Origins J Sound "`l t zr "M: Vit .(az áz0. engineering. Beethoven, at any point In his Shelomo cor trubRn career, is second nature to the men of the Berlin BEN -HAIM: From Israel The Samuel Goldwyn George Neikrug, cello Motion Picture at Philharmonic heard here. Jochum leads a Production per- Leopold Stokowski conducting Symphony of formance of ease and grace. Very low noise the Air FOP Mr levels permit miking that is far more distant United Artists UAL -7005 ) than ours. The recording curve is flatter than Shelomo, the brilliantly -hoed Hebrew rhapsody 1k7aï: nine- tenths of those now in use. Stereo defini- for cello and orchestra, has never before been tion and separation in this particular disc were heard on disc in the sumptuous sound United better with the phasing switch in a reverse Artists provides in this latest version. Sample position. the first statement of the cello with a compliant MENDELSSOHN: Italian Symphony pickup of reasonably flat response. As the music TCHAIKOVSKY: Capriccio Italien slowly cascades to the lower register of the Edouard Van Remoortel conducting Orchester instrument, you'll hear subtle inflection below Der Wiener Musikgesellschaft the point where earlier records mustered a StereoVox STPL 511.210 peaked harmonic or faded away entirely. As Vox displays refreshing candor in setting up engineered by Bob Blake, this record is one of a special price of $2.98 for one of its regular the very few to offer the fundamental lows of releases. This item, one of the first in its new the cello when heard in the company of an Thriftmaster series, is to all intent and purpose orchestra. Stokowski's concept stresses the a normal $5.95 stereo release with one of their majesty of the work's Biblical background. The better conductors leading a middle -grade Euro- other piece, a suite by the leading Israeli com- pean orchestra. The only difference I could de- poser Paul Ben -Haim, draws upon Porgy and Bess (Original Jewish and Sound Track Recording) tect between this and full -price Vox discs arriv- Middle East material. Columbia Stereo Disc OS -2016 ing in the same shipment was one of hall Samuel Goldwyn's notion- picture version of acoustics. Remoortel does not enjoy the full - Pipe Organ Masters, Vol. 2 Gershwin's moving folk opera has caused enor- bodied sound heard in a companion release where- Eugene Gigout, organist mous activity within the record industry. With in Jonel Perlea leads the Bamberg Symphony Fulton Productions OF -5A the release of the movie's sound track, Columbia Orchestra in an ingratiating performance of This disc is part of a remarkable series of has two stacks of blue chips in its corner, the the Dvorak Fourth. Symphony. I've heard more six records issued by a small firm in Tulare, complete opera issued 7 years ago and the score exciting readings of Tchaikovsky's Capriccio Calif. With great patience, Fulton Productions as heard in the film. The 12 sound tracks of Italien than Remoortel manages here but the has transferred to dise the playing of famous the movie version were mixed to form the two Mendelssohn is a good buy at this price. Plenty oranists captured long ago on perforated paper channels heard in this release. The typical of ebullience in the stereo. rolls similar to those used in player pianos. The Hollywood equalization in the sound track intro- music heard here was originally recorded in 1912. duces a problem that is not new. The peak in Holiday in Brazil The Bud Shank, alto sax, and Laurindo Almeida, range of frequencies, dynamics and musical the mid -frequencies causes sibilance in some of guitar expression exceeds that of piano rolls and disc the songs, not the tractable sibilance heard on World Pacific Stereo Record 1018 recordings made at that time. The organ rolls any wide -range sound system but an out -of- were produced by the Weite Co. of Freiburg, control peak where World Pacific was one of the first record com- Columbia's curve meets that panies to solve the Germany. For playback, Fulton has used a spe- of Hollywood head on. The has early problems of the stereo stereo a depth disc. From master tape to finished cially built pipe organ that duplicates closely beyond the average. It is used with skill and pressing, their audio quality has been consistently first - the recording instrument destroyed during imagination in the sequence depicting a morning World War II. Although the chance to hear the in Catfish Row. Although this album rate. This is demonstrated in these subtle Latin enjoys the compositions and arrangements by guitarist playing of past masters such as Eugene Gigout, advantages of stereo, it does not displace the Max Reger and Lynwood Farnam will mean complete three -record Laurindo Almeida. In addition to the fluent alto opera set (Columbia sax of Bud Shank, Holiday in Brazil offers most to organ fans and students of the instru- OSL -1621 . crisply miked drum and tabla stylings by Chuch ment, audiophiles will find much that will amaze ELGAR: Enigma Variations Flores. Much of the charm of the unusual in- them in the tonal range covered by this ancient VAUGHN WILLIAMS: Fantasia on a Theme by strumental combination would have been lost recording medium. Thomas Tullis in mono recording. William Steinberg conducting Pittsburgh Musica Hungarica Symphony Orchestra ,hx3n[s Cowhpyrt, KODALY: Dances of Galanta; Marosszek Dances Capitol Stereo Record SP -8383 BARTOK-WEINER: Two Roumanian Dances t11fING ' Those who prefer a softer and more spacious STEREO" Antal Dorati conducting Philharmonia Hungariaa will Orchestra stereo sound find these two British works Mercury MG -50179 to their liking. During some of the variations Formerly on Epic depicting various friends of Elgar, the music THE WILD WILD WEST available the label, this unusual orchestra is a very logical addition to sinks to a whisper in the strings. In spite of the greater- than -average distance traveled the Mercury instrumental roster. Virtually the by entire membership of the ensemble fled from the sound, a hum -free system maintains contact Hungary during the of 1956. Repre- with the composer's ideas at levels below those of uprising comparable mono recordings. senting most of the leading musical organiza- The Vaughn Wil- tions of that country, they have been welded liams Fantasia illustrates very effectively the into a fine group by Hungarian -born Antal interplay of the two string orchestras specified who by composer. Dorati, now spends part of each year the working with them in Europe. The Vienna locale MOZART: Sinfonia Concertante (the Great Hall of the Weiner Konzerthaus) is HAYDN: Sinfonia Concertante an ideal acoustical setting for the familiar Mer- Eugene Ormandy conducting Philadelphia cury monophonic technique based on the single Orchestra omnidirectional microphone. It would surprise Columbia Stereo Record MS -6061 no one if Mercury were to rerecord a good deal This record will hearten veteran collectors of the Hungarian repertory under these con- who recall with affection the high points of the ditions. Philadelphia Orchestra's career on records. The first -chair players of the orchestra are offered Pieces of Eighty -Eight here an opportunity to display their skill in The Wild Wild West Evans Bradshaw Trio music worthy of their talents. Oboe, clarinet, Ralph Hunter Choir Riverside RLP -12 -296 bassoon, horn, violin and cello occupy prominent RCA Victor Stereo Record LSP -1968 In his second recording for Riverside, the positions in these two compositions, which com- Once you've driven this group of voices through rising young jazz pianist, Evans Bradshaw, bine the appeal of concerto and symphony. The two Ultra- Linear channels, you won't want to provides further explanation of his success to music is delicious and the tonal range lies easily go back to the artificial city ways of most rec- date. He is not afraid to commit himself to a within the capabilities of today's stereo cutter. ords. Don't take my rave for it. Trade in your detailed concept delivered with conviction. I The result is a disc commendable from any last pouch of gold dust for this disc and audi- suspect that, in the privacy of the home, Brad - standpoint. tion it at the fanciest audio saloon in town. shaw's work will be enjoyed by jazz fans who are reluctant to admit in public their boredom BEETHOVEN: Symphony No. 2 The presence is fabulous. Listen for the intake Eugen Jochum conducting Berlin Philharmonic of breath at the end of the stanzas. The ranks with some of today's aimless keyboard jazz. In Orchestra of voices advance into the room in the cre- addition to two of his own originals, Bradshaw Deutsche Grammophon Stereo Record DGS- 712006 scendos, with colorful accompaniment furnished is backed by alert bass and drums in a varied Performances recorded in Europe by this lead- by banjo, guitar, harmonica and bass. In addi- collection of tunes by Strayhorn, Porter, Gersh- ing German firm are now available in this coun- tion to traditional tunes such as Red River win and Gillespie. ENO try under the familiar yellow and blue label at Valley and I Ride an Old Paint, the album also Name and address of any manufacturer of domestic prices. Formerly imported from Ger- features some seldom- encountered gems that en- records mentioned in this column may be ob- many for the benefit of collectors willing to pay livened social life in frontier dance halls and tained by writing Records, RADIO-ELECTRONICS, the price, Deutsche Grammophon discs are now refreshment parlors. An added touch of realism 154 West 14th St., New York 11, N. Y. 42 RADIO -ELECTRONICS

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PICTURE-QUALITY CONTROL

For more pleasing TV reception you may wish to add a picture -detail control to your set- several such circuits cure shown here

By A. V. J. MARTIN

THERE are several simple ways to improved if boosting is carried to the of a few hundred ohms shunted by a improve the picture quality of any point where a fine white line follows large -value electrolytic capa. itor (C) television receiver or, more exactly, black surfaces and vice versa. A sup- (see Fig. 1 -a). When the PQC is in- to better adapt it to the spectator's posedly uniform shade may exhibit cluded, the circuit looks like Fig. 1 -b. taste. Such a control is similar to the changes in density over large areas, The do cathode bias is pr) ided by tone control on radio receivers and, and blacks and whites may be less deep. resistor R1 and potentiometer R2 in like its audio counterpart, will probably (Circuits for modifying the response series, the total value of (R1 + R2) provoke hot discussion. of TV video and video if circuits have being equal to R in Fig. 1 -a. The high - However, the customer is always been used in a number of American TV value electrolytic capacitor C2 is con- right in the long run, and if he likes sets in the past. The 1956 Conrac Fleet- nected between slider and ground, and his picture over -sharp or over -soft, by wood sets used a variable capacitor as a small -value additional capacitor Cl all means let him have his way. Besides, a manual definition control across the is connected between slider and cathode. the very name Picture Quality Control secondary of the second video if trans- When the slider is at the cathode end (PQC) is an important sales point. former. It was used to peak the video of R2, the circuit is exactly equivalent The general principle of picture carrier and sharpen the picture or to Fig. 1 -a and the video response quality control (PQC) is to modify the attenuate the carrier and soften it. curve is undisturbed. When the slider receiver's overall response curve, either Seine Radio Craftsnie }i RC -100 re- is at the low end of R2, there is cathode in the post -detection video amplifier or ceivers had a local -distance switch for negative feedback which reluces the the if amplifier. In this way, one can the same purpose. The switch shorted tube's overall gain. Howee-er, R2 is boost the low or high frequencies in the a section of one of the video if coils to shunted by Cl, and the value of this picture at will. peak the video signal. The DuMont capacitor is such that it practically When low frequencies are boosted, RA -340, Capehart CX -38X and some short- circuits R2 for the highest fre- the apparent contrast is better, the models of other makes had if circuits quencies of the video spect_um, thus blacks and whites are deeper, the large whose response varied automatically suppressing feedback and i.nsaring full areas are uniform and the overall effect with agc bias to provide optimum pic- gain of the tube at high fee «luencies. is a general softening of details and tures under different signal strengths. If the PQC is not going t, be man- outlines. Definition is reduced, and the ( See "Trends in TV Receiver Circuitry" ually controlled, replace R2 with a fixed picture lacks details. This is adequate in the July, 1956, issue.- Editor) resistor of the same value, as in Fig. when the spectator is at some distance Let us now examine some practical 1 -c. This circuit appears in a number from the receiver, where details are lost circuits, first when PQC is applied to of forms in many television receivers, anyway. At such a distance, the im- the video amplifiers and then when it where it is used as part of the video provement in large areas does much to is incorporated in the if amplifier. amplifier compensation system fo obtain provide a more pleasing picture. a flat response curve. The purpose of When high frequencies are boosted, Cathode feedback the PQC is different, as we have seen outlines are sharper, the transitions A very simple and effective way to previously. Note that adjusting the from black to white or white to black control the response curve of a video PQC does not modify the ) erall gain are better and the details appear more tube is to include selective negative for low and medium fre :encies. A clearly. The overall impression of high feedback in its cathode circuit. Usually, practical circuit, used in the French definition and sharpness can be further this circuit consists of a resistor (R) Opera receivers, is shown i° Fig. 1 -d.

6CK6 6CK6 u26AU8 1/26AU8 1/26AU8 1/2 6U8 1í2 6U8 v2 6U8

EE-

001 ?560 820 + POC .0039 CI POC R2 .001 POC 80 POC 1500 2 TOOC. 02:loon R2 CI IOO n l4d 100 470 82 n pf + :002 +T500 + 500 100 . +lI C2 RI 18013 1 fa P :0039 {470. T- SO 54713 Izon st 330

a C h

Fig. 1 -PQC through cathode feedback.

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For the American standard, the value sponds to the normal of response curve the small capacitor should be in- (curve B in Fig. 3). creased to .002 pf. In some models, the same manufac- Q J Grid PQC turer uses wf a fixed PQC as in Fig. 1 -e. A different type of control is used Here again, the value of the small on some Nordmende receivers. capacitor FREQ Since should be .002 pf for the - the video amplifier contains correcting American standard. This circuit is easy Fig. 3-Effect of Fig. 2 -c circuit on inductors to insure that the response to add to an video- existing receiver, keeping frequency response. curve is flat up to the higher limit of in mind that the total cathode resist- addition of a .001 -pf capacitor (Fig. the video spectrum, a simple PQC could ance should be the same as the original be obtained by modifying value. 2 -b) introduces automatic PQC. For the inductance As there is also a slight reduc- value of the compensating coils. tion in video distant stations and low -level signals, How- gain the receiver must ever, this introduces some difficult prac- have some reserve in this respect. This, where high- frequency boosting is un- desirable, the slider is at or near the tical problems, mainly due to the dis- however, is never bothersome, for the tance between the control PQC cathode end for maximum gain. This and the coils. would hardly be installed in A neat solution has been found marginal cases. effectively puts the capacitor across a by the low-value German makers. The PQC is obtained The circuit of 1 -b resistance and its effect is Fig. has been tried by varying the inductance of series on a G -E 17T025 receiver. The original small. For local stations and high -level signals, when the picture can stand correcting coil L in the grid circuit of diagram is given in Fig. 1 -f, and the the video high -frequency boosting, the slider is at amplifier (Fig. 4 -a). This modified version in Fig. 1 -g. The exist- coil is wound ing cathode or near ground, the capacitor is con- on a ferrite core, and resistor may have a low this core is placed in the field value, say less nected across a high -value resistance of an than 100 ohms. If this electromagnet. The magnetic field is so, the and its effect is maximum. Thus the can resistor can be entirely re- be adjusted to any value with the help placed by a potentiometer. This has amount of PQC increases automatically with the level of the received signal. of potentiometer R2, and the ferrite been done in the G -E receiver, as in core A somewhat similar arrangement is, is more or less saturated. Its Fig. 1 -h, with better results. A certain permeability varies with saturation, amount of parasitic wiring capacitance in fact, provided in some TV receivers, such and so does the inductance of coil L. is unavoidable, but it does not hinder as the RCA 21 -T series, or the Westinghouse V -23 series. In the latter With the slider halfway, coil L is circuit action. Sometimes it can be such that it has the correct inductance made part of the correcting capacitor. the shunt capacitor is replaced by the parasitic wiring capacitance, mainly value for normal flat response. Mod- It may turn out that the cathode ifying the current resistor due to the shielded cable connecting the through saturating is shunted by a low -value coil Ls thus provides for lifting or capacitor as part of the correcting net- cathode to the contrast control. work. This VIDEO happens in the first video Improved cathode PQC amplifier of a Philco 7L70 represented AMPL More sophisticated 10 in Fig. 1 -i. There are two possible circuits can be solutions. Either the existing capacitor devised. An example is given in Fig. is used across the fixed resistor (Fig. 2 -c. It represents the video output stage of a 1 -j) or it is replaced by an electrolytic German Loewe -Opta model. Neg- lecting L for the capacitor (Fig. 1 -k). The latter time being, the circuit circuit is gives a better range of control. Note similar to Fig. 1 -b, except that Cl that this PQC provides for an increase has been replaced by R1, Cl, C2 to and decrease of high -frequency gain. obtain a more progressive effect. How- The examples show that installing ever, inductor L is also included in the cathode cathode circuit. As its impedance in- PQC in the video amplifier of a 6 a TV receiver is neither difficult nor creases with frequency, the cathode feedback increases and the gain de- Fig. 4-PQC in the video -amplifier grid expensive. It will, moreover, prove circuit. profitable to the alert service technician. creases for the high frequencies of the video spectrum. Its effect is exactly lowering the high -frequency part of the Automatic PQC opposite to that of a capacitor. video response curve. Inductor L resonates with its para- This A number continuous PQC can be replaced of receivers use cathode sitic shunt capacitance near the upper by feedback or cathode bias a step -by -step control, as in Fig. 4 -b. as a contrast end of the video spectrum, say 3.5 or Actually, in the German receiver three control. Simple modifications let you 4 mc. pushbuttons add PQC to such receivers. are provided. One is labeled Moreover, The 500 -ohm potentiometer does two "Live ", another "Film" and the most circuits lend themselves to third the jobs. When its slider is at the ground "Brilliant." The last one may be added installation of automatic PQC. Take end, inductor L is short- the circuited and to the other two. This arrangement already cited Philco 7L70 as an put out of action. Simultaneously, the gives the viewer example. Its second video a choice of light amplifier uses shunt effect of the capacitive branch tonalities exactly to a 6AQ5 with contrast control equivalent the fixed in the Cl-C2 is at maximum, so that the positions (voice -music) of certain radio cathode, as in Fig. 2 -a. The simple negative cathode feedback is reduced tone controls. and the gain is increased for the upper video frequencies, PQC in the if amplifier 6AQ; 6AQ5 as before (Fig. 3, curve A). The PQC can be obtained by modify- t VIDEO VIDEO AMPL OUTPUT When the slider is on the cathode ing the if response curve. Normally, side, the shunt effect of the capacitors this curve is adjusted so the if value 9 is minimum. At the same time, the of the carrier corresponds to a loss of CI.00IS inductor comes into play, the negative 6 db, that is 50 %, in gain, relative .001 ) 2000 feedback is increased and the gain is to the center of the passband. This is 1.5 K 1.5K RI C2 reduced for the high video frequencies indicated by curve A in Fig. 5. For C soon (Fig. 3, curve C). such tuning, the overall response curve R2 Between these two extremes, any of the receiver is flat down to very low 5000 CONTRAST intermediate effect can be obtained at frequencies. If, by deliberate mistuning, A will. The values of the elements are the if curve becomes curve B, there is s so chosen that the capacitive and induc- an overamplification of the low fre- a 6 tive effects just balance each other when quencies. Conversely, curve C atten- Fig. 2- Evolution of a PQC circuit. the slider is set halfway. This corre- uates the low frequencies. The effects 44 RADIO -ELECTRONICS

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AMPLITUDE Fig. 7-Effect 6U8 100% of Fig. 6 cir- MIXER TO IF 6CK6 -3 DB cuit on low vi- AM- PL VIDEO AMP_ TO PIX deo frequencies.

-12 DB FRED- PIX IF CARRIER 25 MC 26 27 28 Fig. 5 -The effect of modifying the if FRED response curve. IF CARRIER mc, slightly above the if carrier fre- Fig. 8- Combined circuit uses if and 6BX6 video amplifier PQC. LAST I F AMPL quency. The setting of potentiometer Rl determines the damping and hence the efficiency of the trap. The result is is amplified and reversed in phase at Fig. 9. The effect is, as before, a vari- the plate of this tube, and applied to able attenuation on the if carrier. the short- time -constant coupling circuit., C2 On the video side, in the anode cir- which again differentiates it. Each R2 cuit of the video output tube is correc- plate pulse is then transformed into 2K tion coil L2. This coil is shunted by a pair of short opposite pulses. potentiometer R2, so that its effect in .005 i RI These pulses are added to the original T 18052 high -frequency boosting depends on the video signal at the grid of the video setting of R2. amplifier. One of the pulses will be in R1 and R2 are ganged, and the same Fig. 6 - Definition- corrector circuit such a direction that it will sharpen the gives PQC by modifying if response. control accordingly determines the rise of the signal. The other pulse will amount of PQC in the if and video be in the opposite direction and produce of such mietunings are well known to amplifiers. a sharp white outline around black the technician; they are very easy to areas and a sharp black outline around obtain, sometimes quite unintentionally, Amplified PQC white areas. when tuning the if amplifier. An elaborate PQC has been devised A trap circuit, tuned to the sound They can, however, be put to good by Schaub -Lorenz. Its principle is en- if, has been provided in series with the use for PQC. A simple arrangement is tirely different from the preceding cir- short time constant coupling circuit. given in Fig. 6. The circuit is included cuits. The complete diagram of the Potentiometer Rl adjusts the bias of in some French Oceanic receivers and video amplifier is in Fig. 10. the pentode amplifier and hence its is labeled "Definition Corrector." The Notice first the use of a plate and gain. if corresponding to the carrier is 27.5 cathode loaded triode after the detec- This circuit does not modify the mc. Tuned circuit L -Cl is a trap cir- tor. The plate circuit feeds the sync response curve. It does not increase cuit, normally resonating on 27 mc separator. The intercarrier sound take- the bandwidth. and coupled to the cathode of the last off is on the grid. The low impedance It does, however, improve the appar- if amplifier tube by a small primary cathode circuit feeds the video amplifier ent definition of the picture by shorten- winding. through a potentiometer which con- ing the transitions and setting them When potentiometer R2 is at its stitutes the contrast control. against a contrasting outline. All in maximum value, the shunting effect of The coupling circuit to the 6CK6 all, the picture looks sharper and capacitor Cl on the tuned circuit is video amplifier is more or less standard. crisper. END negligible and the trap resonates on 27 It includes series correction coil L and mc. The tuning of the if amplifier is crystal clamping diode D in the grid AMPLITUDE such that the if carrier corresponds circuit. 100% then to an attenuation of 12 db, and The originality of the circuit is in the low video frequencies are strongly the use of the pentode section of the attenuated (curve A, Fig. 7). When 6U8. the potentiometer is in the short -circuit Across inductance L appears a volt- position, capacitor C2 shunts the trap age which is roughly the derivative of circuit and shifts its resonance to 25 the video signal. That is, for each rapid Fig. 9 -Effect mc. The attenuation on the if carrier transition of this signal, a pulse appears of pot Rl in is then only 3 db (curve B, Fig. 7) and across L and is applied to the grid of FRED-y Fig. 8 on trap TRAP there is an overamplifiiation of the the pentode part of the 6U8. This pulse efficiency. IF CARRIER lowest part of the video spectrum. The setting of the potentiometer provides any intermediate curve be- 10µµf tween curves A and B, including, at I SOUND TRAP mid -setting, the normal curve with 5°PP - 1 6 -db attenuation on the i e carrier. This circuit may be added across a v2 6U8 6CK6 2D VIDEO AMPL TO PIX trap circuit in an existing receiver. It IST VIDEO AMPL TUBE uses only one capacitor s.nd one carbon 3K potentiometer. 15 K FROM

VIDEO B it Combined PQC DET The two principles of picture quality 1.5 K 30K RETRACE control, in the if and in the video ampli- TO SOUND .05 BLANKING fier, can be used jointly in a combined IF AMPL 5052 PQC. A commercial circuit, developed 3K IOK IOOK by Schaub -Lorenz, appears in a some- 150 Sl I00 what simplified form in Fig. 8. A trap Fig. 10- Elaborate amplified .05 circuit Ll -C is connected at the output PQC circuit devised by of the mixer tube and tuned on 39.5 Schaub -Lorenz. AUGUST, 959 45

www.americanradiohistory.com Personal TV sets -long a dream TRANSISTOR of viewers and designers -are now a reality. First of its kind on the market, Philco's new portable introduces a new era in TV view- PORTABLE ing

By Allan R. Curll and Paul V. Simpson*

THE new transistor portable TV's Channel and fine - have been developed to take full tuning controls advantage of the benefits that may at upper right; be obtained in a transistor design. on- off -volume, con- The light weight (15 of the trast and age range pounds) controls are on pioneer Philco model 2010L shown on left side. the cover and its small size illustrate two of the more important of these. The receiver operates from 117 volts imp ac or from its own battery, a function switch changing from one power source ...... to the other. It draws approximately 4.5 watts from its self -contained re- chargeable battery. In the AC position, the receiver is isolated from the line by its own built -in stepdown power o transformer. This transformer is also used to supply energy for recharging the battery in the charge position. The television set (Fig. 1) employs 21 p -n -p transistors, 14 diodes and the CR tube. All the transistors in the set were designed and manufactured at the Lansdale plant of Philco Corp. The tuner uses three MADT (Micro Alloy Diffused Transistor) type tran- .411111111111 sistors, T -1561 rf amplifier, T -1600 mixer and T -1597 local oscillator. In- put selectivity is provided by a single tuned parallel resonant circuit capacitively tapped to match the rf amplifier's input impedance and inductively VERT tapped at the 75 -ohm point for the HOLD monopole antenna. The T -1561 rf HORIZ amplifier is connected in a neutralized HOLD FUNCTION common -emitter circuit. A double -tuned SWITCH bandpass circuit is used between the BRIGHTNESS rf stage and T -1600 mixer, the input of PHONE which is capacitively matched to the JACK double tuned preselector. The mixer is AC also operated in the common- emitter INTERLOCK configuration, and oscillator energy is injected into the emitter for proper mixing action. The oscillator may be regarded as a common -base amplifier in which additional capacitive feedback has been added between collector and ELAPSED emitter to sustain oscillation. Typical TIME 1 10 INDICATOR system noise factors range from -12 Rear view of cabinet. Manually db in the high channels (7 -13) to 6-8 operated elapsed time indicator db in the low band (2-6). Matched keeps drain. track of battery tuner power gains vary from 32 to 28 Philco Corp. 46 RADIO -ELECTRONICS

www.americanradiohistory.com TELEMLSION db on channels 2 through 6 and is stage. A three -position range switch in AUX VERT LIN approximately 18 db in the channel 7 -13 the collector of circuit this amplifier 4111111MIIIIIPRIMMIN region. controls the collector voltage to the tuner and the agc gain to the if. The video circuitry The collector of the video output The video if employs four MADT stage is returned to -12 volts and the p -n -p triodes designed for 45 -mc serv- emitter returned to +12 volts. In the ice. These are used in the grounded - absence of signal to the base, the collec- emitter configuration for maximum tor normally runs at approximately 0 gain. Conventional stagger tuning is volts. In the presence of signal, it can used to obtain an acceptable transient swing from +12 volts to -12 volts, response. The overall gain bandwidth resulting in a maximum drive to the HEIGHT of the if is approximately 70 db at CR tube of 24 volts. 3 mc. (The first IFT consists of L2 AUX Ll, The sound system VERT and L3; second IFT, L4, L5, L6; third HOLD IFT, L7 and L8; fourth IFT, L9, L10 Sound from the emitter follower and L11.) (first video amplifier) stage is amplified AUX in a 4.5 -me sound if stage which drives HORIZ One of the more serious problems HOLD confronting the designer is that of a limiter. Limiting is accomplished in obtaining adequate selectivity for adja- this stage by driving the collector of cent picture and sound. This problem the limiter from saturation to cutoff. arises because of the extremely low The balanced ratio detector drives an audio driver which in turn drives a input and output impedance of the DRIVE J transistor. The input impedance of the pair of push -pull class -B output units. LEVEL type of transistor employed is approx- The output is approximately 150 mw imately 100 ohms as compared to a 3 -inch speaker. to the Set's cabinet is removed to show under- input impedance of a vacuum tube of Sync and noise switch side of if, video, audio and sync printed - 20,000 ohms. The if amplifier strip in circuit panel and easily reached service the 10AT10 chassis as discussed here The sync separator is driven from adjustments. overcomes this by employing a balanced - the collector of the video output stage T 47.25 -mc trap for adjacent sound through a double time -constant network. The peak -to -peak signal on the base a diode and turns the switch to the off trapping and a series -tuned 39.75 -mc position for the duration of the noise trap for adjacent picture trapping. The of this stage is approximately 5 volts with sync negative; sync turns the spike. When this stage opens, the sync trapping ratio is approximately 40 db. separator also opens, preventing noise To obtain agc action in a transistor separator on and drives the collector to saturation. The separator is returned reaching the horizontal and vertical at the present stage of the art, two oscillators. techniques have received considerable to ground through the collector -emitter attention. These are forward and re- junction of the noise- switch transistor, Deflection circuits verse agc. Both techniques are em- the base of which is returned to the ployed in this receiver. In the reverse video detector. In the presence of im- The cathode -ray tube used is a 2- mode, the emitter and collector cur- pulse noise, the video detector goes inch Lansiale type with a 30- degree rent decrease with increasing signal negative about 5 volts. This voltage is deflection angle and a 1 -watt heater. ac- coupled to the noise A strength ; in the forward mode, emitter switch through three -stage circuit is used to drive and collector current increase with signal strength. A voltage which goes negative as the signal increases is applied to the base of the first and second IF transistors. This results in a large voltage drop across the large emitter resistor. Less voltage appears across the transistor so the gain of the DE=L `OKE stage decreases. In the third stage, the base -emitter diode is biased in the reverse direction as the signal in- FUNC- ION creases. As the collector- emitter volt- SWFTC-1 age does not change, the gain of the (AC - SATT- stage decreases. CI - ARGE ) The reason for using both forms of age is that the output impedances of the CENTERING stages vary with agc. Thus, when the MAGNETS emitter current increases in a stage operating in the forward mode, the PHONE JACK bandwidth of the stage increases whereas in a stage that is operating in the CRT reverse mode, the bandwidth decreases, for an increase in emitter current. Thus, to maintain constant bandwidth AC INTERLOCK for varying signal condition, employing both forms of age action is an aid. BE AM ALIGNING A conventional crystal type video MAGNET detector drives the first video stage. This stage is used as an emitter follower to obtain correct impedance matching between the detector and the video output stage. The first video is direct- coupled to the detector and age is obtained from the collector of this Closeup of rear chassis with battery removed to show service consols. AUGUST, 1959 47

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r 44.7 MC Fig. 1- fl 15µµf .5-31y.f y RFC = T15970 RFC 75 dl ANT INPUT 1-3.8µ4f 30µµfl OSC ¡ T 1600 -(3$1 !2K_ T1561° J_ 1.8µµf ,ar 91 51`Pf )(1MIXER 1.5µµf RF AMPL_ = 8µµf I-3.8µµf = r CHAN l r llll 13 RFC CHAN 13 FINE I2K COIL 4.1.2K COI L FTRAP TUNING ) Ió43.5MC 12K 3.9 I5µµ 001 i- ¢q µµf 39K 43.5 MC ) µµ HI( .001 CHAN 13 1.5 K 4M.71K 20 - i 2 12K =.001 COIL µµf =.001/ IOOµµf 001 IF TRAP f o CHAN 13 COIL I= 12V i lo. LoF-o o 13 BAS _ CHAN FROM 13 2 AREA o1 TAP SW COIL T 1559 o I I IST VIDEO *GIMMICK (CHAN 13 IF AMPL BANDWITH) . 96 µ H 10 o 45.3 MC CHAN = 10 GNDED o TAP ©CASE COI L T 8 o LI 7 o CHAN 6 15µµf CHAN 6 ADJ CHAN 6 COILS COIL

CHAN 47.25 MC t = 6 TRAP TAP CHAN 4 3.3µµf

COIL COIL 1 41.25 MC TRAP

I J CHAN 2 o COIL

o o Ìr o o GIMMICK .82µµf .0022 POSITION NOT USED J r.33 2.7 K, TES oPOINT T1596 5 %. )(-1.8K .047 .33 10K SYNC SEP 3.9K 5% .068 -1 1068 6.8 K .01 2N531 .008 68K NOISE VERT LIN 1 - -12 V SWITCH - I 500 f VERT YOKE r- VERT OSÇ TRANS AUX"- 7511 L 5µµf VERT 22011 3.3K 10 47K = JII álló 2.2K T 1601LIÑ VERT OUTPUT .02 5.6 K VERT OUTPUT TRANS I -ei I.001 5% 2N224 7K 05 500µf I L=____1 VERT 43011 OSC 5% 15µµf 13.5ÿ 5µµf 12V AUX + "/ -6V 300µf FáLb 10 S2 -6V +1200µf 15011 5V 120 V 100µf 43011 VERT 10V 5% IK HOLD . PANEL 12V -6V L VERT OUTPUT the horizontal yoke. The first stage The output switching transistor sup- used in this circuit to obtain good is the low -power high -impedance block- plies the energy for the yoke and high linearity. ing oscillator, driven from a conven- voltage and also for the +12, -12 and tional balanced phase comparator. +300 volts supplied by the T50, T200 Power supply The buffer circuit, which is essentially and T400 diodes. The flyback trans- The power requirement for the re- a switching device, supplies sufficient former has a turns ratio of approx- ceiver is 700 ma at 6 volts. current to the output transistor to imately 100 to 1 and drives a high - The power during ac operation is drive it to full output during scan. It voltage doubler circuit of two 5642 provided by a stepdown transformer. must supply the high reverse- current high -voltage rectifiers. Full -wave rectification is used to min- spike necessary to cut the output tran- Vertical sync is integrated in a con- imize circuit losses and thus prevent sistor off rapidly at the start of flyback. ventional circuit and drives the tertiary unnecessary temperature rise within The buffer stage switches at the same of a tightly coupled blocking oscillator the receiver. The battery is switched time as the output circuit but not at transformer. The vertical hold controls out of the circuit during ac operation the same time the blocking oscillator are in the emitter of the oscillator to to obtain maximum life. is on. This permits the use of a low - maintain good frequency stability with The battery is an alkaline unit that power oscillator whose repetition rate respect to time and temperature. The weighs 1.6 pounds. Built into the re- is unaffected by variations in buffer or vertical oscillator is ac- coupled to the ceiver, it has been designed to operate output stage loading. output stage. Considerable feedback is on a 4 -hour discharge cycle. Each dis- 48 RADIO- ELECTRONICS

www.americanradiohistory.com TELEVISION Preproduction schematic of the Philco 10ATI0 portable TV chassis.

TI595 T1598 IN60 -A (2) 2N 4.5 MC LIMITER 4.5 MC RATIO DET .047 225 (2) AUDIO OUTPUT SPKR IK VOL CONT T 1001 DRIVER `- . (PHONES) .I PRIVATE ÓI 3311 6.811 .I á LIST: N ING JACK.. 27K ° 12011 1.5K

+ 18 <.2.2K -6V -6V 10V BIAS TO TUNER 4.5MC n 11593 °C W T 1559 T 1559 4TH IN60-A IST 33011 LD VIDEO 5 3.9K VIDEO 2ND VIDEO 3RD VIDEO DET) Cr- 4.7 IF AMPL µµf 10 H 000 820 41.25 MC IF AMPL VIDEO 44 MC / AMPL 6800 39.75 MC µµf µµf 44 I.8µµí IF AMPL I.Bµµf 1 1 1 5% 3µH ' 1 MC 2.7µµf 4.7 1.0068 1.5 µµf 44 MC 3.9K L2 µttiÌ -12 V J .0017 L3 L9 w .001 - 1.2 K 1001 TEST°;1 IK ¢ 3.3µµf 3.3 o µµf IK POINT o DRIVE 22011 12 L4 2.2K T001 I00K T.001 247Nµf LEVEL 12 K 5% 12K-5% 45MC NOISE SW 12V 3300 < c 02 2 I( N60 6.8K DIODE .& 1 -A z 2' 3.3K 4300 .001 12 V J O 39 K CC 5%12V 33K 12V 3.3K -5% 12V 1.5 MEG = CONTRAST 47011 12V -----MHr- AGC LINE 47011 100µf /5V 270 5 ITEST POINT m50 m10 3000 T1594 1.8 K 8.2K VIDEO OUTPUT 5/ 5% r- 3311 270µH VERT BLANKING LINE - d 12V 10K q .05 ` IE 1N60 -A(2) T1599 2N224 T1602 1N91 WIDTH L----- HORIZ OSC 2.7 K PHASE COMP BUFFER HORIZ OUTPUT DAMPER OµH 27K = I 12 MEG ''Nf _02 3.3 K I I I00K _1 OK .0022 15K 2.7K T I BRIGHTNESS * I) 47 II 50K _J "VW 15 K 8.2K ¡ 1 1-1 4.7 K ' -6V e1 ° Ilo H O RIZ TEST I4 YOKE 12V -t2V 110 2.7K 1 4.7K POINT NE-2 5% 5% l 022 5642(2) sKv aI 1IK 3 .018: HV DOUBLER 2EP4 -6v 7K AUX HORIZ HOLD 20 M EG STAB COIL .221 2.2 MEG -6V 4700 6 K 5K =470µµi .033 680µµf TEST 5µµf --1(-- 6 KV HORIZ HOLD %r POINT - T50 3.3K -I2VRECT 500µµ .001 -1i- "VOr L 5611/Iw -12 V/6MA IO11 6KV +=200µf / 20 V AC BATT CH T400 <--- -- 300V 300V 12 V ON-OFF 30 M 280 CONNECT FOR E B 300 V RECT .01/500V BEST FOCUS

2A T200 I 2.70 I2V/40 MA 117 V AC 1 \r-6V - 1 2000µf 7.5VBATT ¡ =-2000µf/10V I2VRECT 100µf/20V 200µf/20V .001 10 V _2_+ J

charge must be followed by a 16 -hour through the center of focus D of the TWO -WAY MIRROR F recharge. It is recharged simply by mirror. The light rays will also pass plugging into the ac line, may be re- through the mirror's center of curva- D charged about 20 times, and will cost ture, E. The intersection of the light in the neighborhood of $5. rays CD and BE at point F produce a . virtual image of the arrow appearing EYE Optic system behind the set and magnified. The G A arrangement of the optical sys- The optical system has a magnifica- \CRT/ SPHERICAL MIRROR tem and cathode -ray tube is shown in tion of 8. The virtual image produced Fig. 2. The diagram also shows the is approximately 814 x 11 inches and CABINET light paths that produce the magnified appears to fall about 4 feet behind the picture. The light from the arrow receiver, although it is seen through a NOT TO SCALE (shown as an example) at point A on viewing aperture only 71/2 x 3% inches. the CR tube strikes the beam splitter The beam -splitter mirror must be Fig. 2-The optical system. (two -way mirror) at point B. Since designed not only to serve as a reflector this is a reflection surface, it is re- but it also must be transparent since mission to reflection has been chosen flected to point C on the spherical you must look through it to see the to obtain a satisfactory picture under mirror. The light at C must pass magnified image. The ratio of trans- high ambient conditions. END AUGUST, 1959 49

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/ \ ^ 1, l `\ / I _ \../ (II ; / -i THOSE / 1 S. ¡I r / , r / .`,.../¡/!/ ' 1 / ` -..,

;'I I .. . GH When caused by the TV set's circuitry, ghosts can mean trouble. Knowing how to identify an internal ghost and how to scare it away saves you headaches

By JAMES A. McROBERTS

This trailing ghost was caused by a reflected signal.

AT there is another type corroded contact, introducing a high spacing between the two signals. This trouble known as spooks, resistance at the antenna connection, is known as a tunable ghost -one that here we chase ghosts and is a prime source of this trouble. A will change its spacing and polarity want to know if they are in break in the lead -in where it passes due to tuning. All tunable ghosts are the set or not. If you've ever spent an through a window is also a frequent internal and are caused by the set it- hour or so orienting an antenna, only cause of ghosts. The ghost will be self. to find that the ghost was due to circuit spaced in proportion to the distance of A tunable ghost may be due to other action in the receiver, you know the travel of the standing wave (Ll. in faults, but the direct -pickup type is reason why. Fig. 2) for an antenna mismatch, or readily localized. Movement of the body If spacing and intensity of a ghost distance L2 for trouble at the window. near the TV set (particularly the change when an indoor antenna is This type of ghost is temporarily tuner) will change the ghost's inten- substituted for the existing one, you eliminated by using an indoor antenna, sity, but will not affect the main signal know, that the set is not at fault. If the since the ghost will disappear or its (unless an indoor antenna is used). ghost is internal, its spacing and polar- spacing will change. The remedy is to shield the inside of ity will not change appreciably. the set, particularly around the tuner. A look at the principal causes of Internal ghosts Sheet aluminum can be used for this external ghosts shows why. A reflected Closely allied to external ghosts is purpose. Ground the shield to the set's ghost is due to a difference in the time direct signal pickup by the tuner. If chassis. Another remedy is to install the reflected signal takes to reach the an rf tube in the front end picks up a a better antenna (most ghosts of this set. In Fig. 1, path ABC is the route signal, it will have a time difference type come from indoor aerial installa- of the reflected signal. The path is with the main signal picked up by the tions) so that the main signal will be longer than the direct route AC, and antenna and fed into the set. It may much stronger. The age system will the ghost arrives after the regular have a different polarity -the main then reduce the ghost so it will not be program material. The time delay is signal may be white while the ghost is prominent. constant and can be changed only by black. This ghost appears to the left If a signal is fed back from some reorienting the antenna. There is one of the main signal, as a leading ghost. later portion of the set into a stage ghost for each reflecting surface. The fine -tuning control will cause a nearer the antenna, a ghost results if Transmission -line mismatch at the change in the time delay (and phase, the amplitude of the fed -back pulse or antenna or set can cause ghosts. A too) of the main signal, affecting the picture element is sufficient. (Such

50 RADIO -ELECTRONICS

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fl TRANSMITTER amplifier for this test.) By finding the the set's schematic. The symptom will stages over which the regeneration disappear (to one or two rings) when REFLECTING SURFACE path extends, we can find the point of the bad resistor is found. If excessive injection of the spurious signal. Then, ringing is due to a design fault, lower the necessary steps to stop the feedback the resistance on all coils. Cut out any are taken -shielding, lead dress, de- old resistors. Their value may change coupling filters in B -plus, age lines, etc. (again) or parasitic oscillation may develop when resistors are paralleled Phase -shift ghosts in this circuit. Another ghost, with an appearance similar to direct pickup, is the phase - Interlaced ghost / shift type. If this kind of ghost is Another internal ghost is caused by

IRAN TENNA noted, and is due to misalignment, it a sidewise displacement of horizontal will be tunable. It will have an opposite lines. Trouble stems from a slight shift- Fig. 1- Direct - and reflected- signal paths polarity (white ghost for a black signal ing of alternate fields. This tyre of result in a ghost. trailing, external or vice versa). The tunability proves ghost is not tunable and remains con- that the ghost is internal. Proper stant in value with rotation of the adjustment of the if tuning will cure contrast control. Close inspection of one type of such ghosts. Another type the picture will show that each alternate is due to the failure of the fine -tuning horizontal line is displaced -use a control to cover the entire range. This magnifying glass. ghost is eliminated by adjusting the The trouble is in the horizontal out- local oscillator slug or trimmer. put tube's grid circuit. Grid leak is An internal ghost by design is the too low, the tube is defective, voltages ring of the peaking coils in the video applied are not correct, or the drive LI amplifierdetector sections. High fre- control is leaking (capacitor shunt quencies of the video signal shock- excite type). Excessive pickup of vertical these coils into oscillation which is so pulses by misplaced wiring has also loaded (damped) with resistance that caused this trouble. only two or three cycles of oscillation Video amplifier regeneration over a are permitted. A change in the value path like REG in Fig. 3 may cause of the coil resistance or shunting a ghost. Its intensity will be Taried resistance may cause ring to become with respect to the main signal by excessive (visible). varying the contrast control. hi oving Fig. 4 -a is a typical interstage cir- leads around the base of the video cuit using ringing coils -shunt and amplifiers will further confirm this series types. Note associated damping section as the cause. Appearance of a L2 WINDOW LEAD- resistors. If the resistance of any ghost due to video regeneration changes Fig. 2- Mismatching or breaks in an- damping resistor rises appreciably, the in intensity with different programs tenna lead -in produce ghosts due to normal ring of Fig. 4 -b will become the and different stations. The usual cures standing waves. abnormal ring of Fig. 4 -c. Each upper for regeneration apply here. END

udk"- I ID2

REG 2 D3 I PIG

I I

VIDEO VIDEO RF MIXER IST IF 2ND IF 3RD IF DET OUTPUT

RE61 Fig. 3 -Block diagram shows pickup and regeneration paths. Direct pickup at D1 and D2 causes leading ghosts. Regeneration paths-REG' and REG_- produce trailing ghosts. feedback of sync is often the cause of portion of the cycles represents black horizontal jitter.) while each lower peak is white. We have Fig. 3 shows several such feedback evenly spaced rings decaying in inten- paths. An if path may be like REG,. sity on the screen as a result. These It produces a trailing ghost. Spacing may be distinguished from multiple depends on the time difference of the reflections on an aerial lead -in by the main and feedback paths. Any ghost fact that rings follow only short por- involving the if amplifier can be altered tions of the horizontal lines, while appreciably in appearance by varying transmission -line reflections follow all the fine -tuning control. The if is affected abrupt changes whether long or short. by such tuning, and hence the appear- Another way to distinguish ringing ance of the main signal with a similar from multiple reflections (as with an change in the ghost. Therefore, a tun- antenna or set mismatch of the trans- able ghost must be internal and pass mission line) is by varying the contrast over some tuned circuit of the set. control. This will reduce the amplitude A A Localizing such a ghost is ticklish. of the video signal applied to some of . Changing the bias on a stage by alter- the peaking coils at least, and also the ing the value of a cathode resistor may intensity of the rings. furnish a clue-shunt the resistor with Excessive ringing (five or more another. The appearance of the ghost separate rings or ghosts) is cured by will change if that stage is part of the lowering the resistance shunting one or Fig. 4- Interstage ringing coils. When feedback path. (The mixer or con- more peaking coils. Shunt each in turn this ring becomes excessive, ghosts ap- verter may be considered as an if with a resistor of the value given on pear on the TV set's screen.

AUGUST, 1959 51

www.americanradiohistory.com TELEVISION to sweep, and the present flyback and yoke should be satisfactory. Replace the double ion -trap magnet with a single- magnet type. Pincushion elimination I tried to eliminate pincushioning on T V Service a Capehart CX37 by placing small bulletin -board magnets at various posi- A111116 tions about the picture tube. I did not - get much correction. Are stronger magnets advisable? The focus is not too good either. Since pins 6 and 10 are tied together, could better focus be Too IIr- Inomi = - - obtained by returning pin 6 to another point ? -W. J. F., Youngstown, N. Y. conducted by It would appear that the magnets used were weak. Try magnets from ion ROBERT G. MIDDLETON will RADIO -ELECTRONICS TELEVISION traps and I believe you have better CONSULTANT results. The voltage required for focusing can vary greatly from one picture T can't be done! Picture analysis is tube to another. I would suggest using OK, as far as it goes. But by the a potentiometer (about 500,000 ohms), time a job gets tough enough to find to adjust the voltage on the focus elec- its way into the Clinic, experience trode from zero to full B -plus. proves that we usually need more data than given by picture symptoms. Spurious oscillation New tubes have been tried in 99% I am having trouble with an Admiral of the cases. They certainly should 18X4GZ. There are "intermittent" black have been tried, as a first approach, lines (three to five), about 3 inches in the remaining 1 %. We shouldn't apart on the left side of the screen. forget that on occasion two tubes go They are visible only with signal pres- bad at once. Unless both are replaced, ent and are more pronounced on weaker a tube -by -tube check can make a dog channels. Pulling any if tube kilts the out of what should have been a push- lines. Adjusting the drive control over. various resistors and a. capa, for with- changes their appearance slightly. - When tubes are cleared, it's time to out success. -P. G., Johnstown, Pa. R. G. M., Tulsa, Okla. make do voltage checks. This may seem The trouble will probably be found This type of interference is caused by "elementary" but, man, it would knock in the grid circuit of the vertical oscil- your hat off to see how many chassis harmonics from the horizontal sweep lator (see Fig. 1). When the time system, which are picked up by the if or are worked on for days without making constant is too long, the picture rolls up. the basic dc voltage measurements. rf amplifiers, or both. The spurious The most likely cause is an increase in oscillation in the sweep circuit must be Every incorrect do voltage has a reason resistance of the vertical hold control behind sometimes the reason is as eliminated. This is usually done by it- (R187). If necessary, check the 1.2- connecting 47 -ohm resistors in series plain as the nose on my face. Also vice megohm grid -leak resistor (R186) too. versa. with the leads to grid, screen grid, and Again, we have to dig deeper and plate of the horizontal output tube. v26SN7 -GT If necessary, also connect 47 -ohm resis- get more data. Resistance measure- VERT OSC TO VERT tors in series with the plate and cath- ments help. In difficult cases, they will 5l OUTPÚT TUBE ode leads to the damper tube. Connec- sometimes show up shorted turns in a .0047 FROM tions should be made directly at the coil which don't affect do voltages, for INTEGRATOR It example. They can pinpoint bad semi- socket terminals. In severe cases, it is also necessary to connect heater chokes conductors, which also escape do volt- COMPONENTS age tests. MAY HAVE into the heater leads of the horizontal CHANGED output and damper tubes. When the soup gets really thick, we VALUE must drag out the scope and probes, Pix -tube substitution whether we like it or not. A potful of Can a 17BP4 -B be a ac circuit troubles won't show up on substituted for 17CP4 in an RCA 17 -S -349? The re- either do voltage or resistance checks. VERT OSC TRANS -anode voltage is Open capacitors are a classic example. ceiver's rated second MAY BE BAD 13 kr. -P. D., Hope, Idaho. Parasitic oscillation is another. Cross- i talk is still another maddening example. The use of an aluminized 17BP4 -B in Fig. 1 -A picture that rolls upward in- Nobody I know is generator- happy. place of a 17CP4 will be satisfactory, dicates too long a time constant in the provided an voltage of 13 We don't like to take the time and effort grid circuit of the vertical oscillator. accelerating to make sweep-frequency tests. Yet an kv is actually available. can sometimes It is also possible that the vertical experienced technician Sweep -alignment problem pinpoint a circuit fault by looking at oscillator transformer (T111) is faulty. the frequency response of a video, if With the picture rolling up, the .0047- I am having some trouble in operat- or rf section. µf coupling capacitor would not be ing a sweep- alignment setup. I cannot So let's not try to do business from suspected. Of course, if it has been obtain markers on 'rf curves. The wave- an empty wagon. Let's get all the facts, replaced with a higher -value unit, the forms are only about 1/2 inch high on and make life easier. symptom will occur. rf tests. -C. N., Belleville, N. J. I would suggest that the outputs from Vertical roll Practical conversion? both the sweep and marker generators The picture rolls upward in an RCA Is it practical to convert a Zenith are weak on the rf bands. This is the KCS -81 -J. The hold control must be 2438RZ1 from a 16EP4 picture tube to most likely cause of marker invisibility turned to the end of its range. I re- a 21EP4 ? -R. A. B., Burbank, Calif. and low pattern deflection. The best placed the vertical sync amplifier, The 21EP4 is a good choice. It is easy way to check the generator output is

52 RADIO -ELECTRONICS

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Fig. 2 (right) -Basic test setups for testing output of a sweep generator: a- Field- SWEEP strength meter shows sweep output over GEN 0000 low and high channels. b- Field -strength meter shows marker output over low and f FIELD- STRENGTH METER high channels. c- Demodulator probe and DEMOD scope shows sweep output at any center PROBE MARKER SWEEP frequency. > GEN GEN 0000 ac I 6 SCOPE Fig. 4 (below) -Using separate gener- VIDEO ators with an external modulator pro- AMPL duces extended low -frequency sweep signal: a-Modulator termination for extended low- frequency sweep signal. b- Sweep -signal output from modulator extends to about 7 kc before generators pull and lock. -4 Fig. 3 -An extended lbw-frequency sweep signal is obtained because sweep and marker generators are comparatively isolated: a- Outputs from rf sweep and marker generators are heterodyned through the picture detector to get an extended low- frequency sweep signal. b-A typical video b amplifier response curve. with a field- strength meter, as in Fig. the fine- tuning control is advanced. - 2. Measure the number of microvolts F. B., Audubon, N. J. ----..... a.. output from channels 2 through 13. This Information given is not complete, will give a general idea of the rf out- but it appears that the video amplifier put vs frequency. To compare the if is overloading. With reference to Sams q,.,.W output with the rf output, use a demod- 132 -8, check: ulator probe and scope (also illustrated 1. Coupling capacitor C35 from the in Fig. 2). If the generator has a uni- picture detector to the grid of the video form output on rf and if bands, the amplifier tube. Ii i3 same pattern height will be observed 2. Voltages at plate and screen of the b when switching bands. video amplifier tube. Sweep generator 3. Grid leak R28 in the grid circuit of the video amplifier. nect the transformer, compare the How can a sweep generator's output I. De restorer tube V8. schematic in the carton with the be extended down to 40 kc.? Also, please schematic diagram of the receiver, and explain a double -ended demodulator 12- to 17- or 2I -inch screen wire accordingly. probe. -L. M., Detroit, Mich. I would appreciate data on convert- 6CD6 failures The output from a sweep generator ing a Zenith 22H20 from a 12UP4 -B to is extended I hare been working on a Muntz to low frequencies by beat- a 17- or 21 -inch picture tube. -S. F. R., ing the rf sweep output against an rf Jacksonville, Fla. 17B8 in which the 6CD6 fails pre- CW output. One of the simplest meth- maturely. Voltages and waveforms are This conversion is not recommended. ods, for video amplifier testing, is shown normal. Sync is OK. Increasing the The 12UP4 -B is a 52° tube, and to con- in Fig. 3 -a. The generator outputs are resistance of the screen grid resistor vert to a 17- or 21 -inch tube would heterodyned through the picture detec- call reduces picture width. Would it be for replacing the flyback, - tor. A typical video amplifier response yoke, vertical possible to use two output and damper output transformer and for extensive curve is in tubes ? R., Lansing, Mich. shown Fig. 3 -b. When a rewiring. -R. video- frequency circuit or component The advisable course is to try to have the customer trade in re- This report is typical of parasitic other than a video amplifier is to be the ceiver on a large- screen set. oscillation in the horizontal output cir- tested, an extended low- frequency video cuit. The parasitic voltage does not sweep signal can be obtained by using Flyback replacement show up on a scope because its fre- a modulator termination for the gen- quency is too high. The tube is over- A Mireur t i ie chassis 9049 lias a erators, as illustrated in 4 Fig. -a. A uhf burnt -out horizontal output transform- worked and, of course, fails to give mixer crystal is used to heterodyne the normal life. The easiest cure for par- rf sweep and marker voltages. Output er. Could you tell me what transformer I can use and how to rewire the chassis? asitic oscillation is to connect 47 -ohm extends down into the audio -frequency resistors - -E. B., Buffalo, N. Y. in series with the grid, screen range. As in Fig. 4 -b, the sweep voltage grid and plate leads of the output tube. does not "break" until about 7 kc. You can use a Stancor A -8144, Merit Connect the resistors directly at the A double -ended demodulator probe is A -3038, Triad A -99X, Halldorson Z1802 socket terminals, because it is the leads shown in Fig. 5. This type of probe is or Thordarson 26553. You will have themselves which are the parasitic res- used to test rf circuits which operate in to drill one new mounting hole and onant circuits. It is sometimes necessary push -pull with both sides above ground. connect the primary and secondary in also to connect standard heater chokes For example, we use a double -ended series as an autotransformer. To con- in series with the heater leads. Normal probe when testing the input impedance tube life depends upon avoiding exces- of a tuner. sive cathode current. This can be con- 100K 1N34-A VERT trolled by increasing the value of the Video overload screen resistor. Picture fr/ TO SCOPE width can be A Jackson 17T overloads the picture 270p.pf T increased at the expense of brightness badly when the contrast control is ad- ONO by inserting 1 or 2 megohms of resist- vanced. The picture gets completely out Fig. 5- Circuit of a double -ended de. ance in series with the high- voltage of shape. The same thing happens when modulator probe. lead. END AUGUST, 1959 53

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.01 iaif 144 MODULAR CIRCUITS include tubes without heaters, microminiature resistors and capacitors stable over several- hundred -degree temperature changes. Circuits like those shown are multivibrators and amplifiers. TIMM's (Thermionic Integrated Micro - Modules) operate in high- temperature environment, use the heat to cause cathode BIGGEST emission. A circuit only ''; x 2.6 inches long SPEAKER holds 10 diodes, 14 triodes, 14 resistors, 6 driver ever made capacitors. TIMM's are a product of General for home high fi- Electric Co.'s research. delity use is this 30 - inch Electro - Voice giant woofer here balanced by Elaine Lee of the E -V staff. The polystyrene cone works down to below 18 cycles.

SUPER -POWER MICROWAVES from regular ac power with efficiencies up to 80% may be made possible with the amplitron, heart of "sky-hook" system (RADIO - ELECTRONICS, page 6, July) proposed by the Raytheon Co. to keep fixed platforms in the sky by beaming power to them by radio. The Amplitron is a crossed -field vacuum tube which combines high efficiency, high frequencies (at least AUTOMOBILE MIRROR RADIO has 5 transistors, 10 centimeters), high power (megawatts), wide -band char- ferrite antenna, draws 500 ma at 12 volts, delivers up to acteristics (10% of frequency) and low input voltages. Shown 2.5 watts audio into speaker (not contained in mirror). Made above the two top electrodes are heater input; lower left, initially for European sports cars, the radio has a possible rf input; right, microwave power output. disadvantage: inviting vandalism. The Voxson Vanguard is made by F.A.R.E.T., Rome., Italy. RADIO -ELECTRONICS

www.americanradiohistory.com RADIO CONVERTER puts FM in your car

By LARRY STECKLER ASSOCIATE EDITOR

ITHIN a few years FM radio long red wire equipped with an in- The mixer's output is a 10.7 -mc sig- will be standard equipment sulated alligator clip, onto the hot nal which is coupled to if amplifier V3, in the American car. It will terminal of your heater switch or an a 12EZ6, through transformer Tl. V4 be used to supplement the unused terminal of the ignition switch. and V5, also 12EZ6's, operate as tuned present AM radio. But if you want Now you're ready to listen to FM as cascaded limiters, and are largely FM radio for your car today, you have you travel along the road. responsible for the converter's noise - to go out and get a special piece of free operation. V4 is coupled to a additional equipment. It may be a Circuit details 12AL5 Foster -Seeley discriminator straight FM receiver designed for 6- The unit's circuit is stable and noise - through transformer T4. or 12 -volt operation or it may be AM- free. It operates very simply (see The detected audio signal is then FM. Then there's a converter, the diagram). With selector switch S1 in fed to translator tube V7, a 12AD6. Gonset model 3311. It is a standard the AM position, the incoming signal is This tube is an oscillator (simiïar to FM tuner as far as the output of its fed through capacitor C22 to the AM a phono oscillator) tuned to 800 kc, discriminator. But the detector's out- receiver. In this position power to the and modulated by the audio from the put is used to modulate an 800 -kc oscil- translator is turned off. detector. Its output is fed to the auto lator which feeds the standard AM Placing switch S1 in the FM position radio where it is handled just as any car radio. In other words, the Gonset supplies power to the converter and other incoming 800 -kc AM signal would converter takes a vhf FM signal and connects the antenna input to the cath- be. translates it into an AM signal. ode circuit of the first rf amplifier, Afc is provided through a Varicap The unit is simple and compact. It half of a 12E C8 (V 1 -a) . This tube circuit. The Varicap is a voltage - covers the entire FM band (88 -108 mc) operates as a broadband grounded - variable capacitor used to keel) tr)e FM and is easily installed. The job takes grid amplifier. As well as having a low oscillator on frequency. For a descrip- only about 15 minutes. A U- shaped noise figure, grounded -grid operation tion of how this type of circuit works, bracket fits around the converter and provides the low input impedance nec- see "Using the Varicap" in 'RADro- two self- tapping screws fasten the essary for matching to the quarter - ELECTRONICS, May, 1958, page 57. works under the dash. wave antenna. Naturally, with this arrangement, Electrically, the installation is just Vl -b is the second rf amplifier. Rf the fidelity is no better than That of as simple. All you do is disconnect the coil L2 is tuned by capacitor C3 -a. the AM set it is used with. To get the auto antenna from the AM radio and Sections C3 -b and C3 -c of this ganged full benefit of FM sound, simply dis- plug it into the receptacle on the back capacitor tune the mixer and oscillator able the translator stage by pulling of the converter. The lead from the circuits. The output from Vl -b is then the tube. Then take your output from converter, terminated in an antenna fed to the mixer's grid (V2). Also fed pin 7 of this tube's socket and feed it plug, slips into the AM radio's antenna to this point is the afc- controlled oscil- into whatever hi -fi amplifier system jack. Then you clip the power lead, a lator output. you intend to use. END

12 I2EC8 VI EC8 VI-a -b MIXER 5.61H I2EZ6 12EZ6 12EZ6 IST RF AMPL 3Oµ f 2ND RF AMPL 10.7MC IFAMPL CASCADED LIMITERS ll V2 65.6µHt. 1/ßl ,47µµf IST IFT 2ND IFT 1 V4 3RD V5 L2 3µµ4.7µ4,f 10.7 MC 10.7 MC IFT 0.1 TI 2 T2 T3 1( r N I I 100, 81.001 01 7 .01 I-- írrT ,C it { .. 4F- Iz-r" 68K = .01 Ison T.001 C3 -c 5.6µH`` 14.7K 47K 100K V------.01 = TUNING 270 K I00µH 22 µµf IO0µH 1.5 K 4 470 0 00 001 50µµf 47o n 100 1( L - SI-a OFM - 470 4AM T4 .01 IMH +l 182µµf AFC REF DISCRIM ANTENNA BATT =1000µf`. AFC DEFEAT C22 V -427 TRANS t(_r OUT V7 1.5 V PUSHBUTTON 12AD6 Fd)H TRANSLATOR +IOOK .001 = TO AM .01 100K .5 MEG \ 100µµf 7 220 K V6 220K ANT POST \ MNr 7 2 65H FM 100 12V SI-b IMEG 1 µµf 12AL5

1 7.1 AM N °12 DISCRIM I 470µµf DIAL LIGHTS

VI V2 V3 V4 V5 V6 270 .001T 4 5 4 4 4 3 IW .01 .01 .01 .01 V7 3 4 1 4

Converter's circuit uses 7 tubes. Cascaded limiters keep noise to a minimum. AUGUST, 1959 55

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1 Part II - There are easy ways to service transistor equipment. Some of these techniques are described here

RANSISTORSUI.

By LOUIS E. GARNER, JR. fact and fiction

T month we saw how some common such an arrangement. It provides a 2N I36 IST IFT TO accepted thoughts on transistors better control over volume, it minimizes CONVC -3.3V IF STRIP are not true. Now that we've been the effect of any noise developed in the LA steered back onto the right course first stage at low signal levels and, by we are ready to survey the servicing controlling the input to the first stage, end of transistor circuitry. it reduces the possibility of overloading Technicians working with transistors on strong signals. will frequently encounter circuits which The second interesting feature is the have no counterpart in vacuum -tube method used to supply dc operating cur- work. And professional service tech- rents. The emitters are floated above nicians called on to maintain and repair circuit ground, while the collectors are transistor receivers, amplifiers and returned through their loads direct to other equipment may sometimes find ground. In a vacuum -tube amplifier, that their familiar service methods this would be analogous to applying a must be modified to get acceptable high negative voltage to the tubes' results. To see why these things are cathodes and returning their plates to true, let's take a look at a few com- ground. mercial transistor circuits. Such an arrangement, while not -8.5V unique as transistor circuits go, could The schematic for the audio amplifier Fig. 2- Converter used in the G -E 675 cause a service technician to do a transistor receiver. used in the Westinghouse H -602P7 double take, since a check of output receiver is shown in Fig. 1. Four 2N217 stage collector -to- ground voltage would than voltages are important in tran- p -n -p transistors are used -one as a give a reading of zero volts. Imagine sistor operation) but may give very preamplifier, one as a driver and two measuring zero volts plate to ground little deflection on, say, the 5- or 10 -volt as a push -pull power amplifier. The in a properly operating vacuum -tube range of a standard multimeter. The common -emitter circuit configuration is audio amplifier!! technician making a quick check may used in all three stages. In operation, To avoid hard -to- interpret voltage conclude, in error, that there was zero the first stage is R- C- coupled to the readings when checking transistor cir- bias. driver, which, in turn, is transformer - cuits, it is best to check to the common Transistor coupled to the output amplifier. electrode of each stage as a reference converter While this circuit seems conventional point. Thus, measurements could be Measurement difficulties may be en- at a quick glance, it has two features made from base to emitter and from countered in rf and if stages as well seldom found in corresponding vacuum - collector to emitter. as in audio amplifier circuits. Refer to tube audio amplifiers. First, note that Even with this technique, the tech- Fig. 2, where the schematic of the the VOLUME control consists of two nician may encounter difficulties. Note converter used in the G -E 675 receiver ganged potentiometers -R1-a and R1 -b. that there is a difference of only 0.1 is shown. One is connected ahead of the first volt between the base and emitter of Here, a 2N136 p -n -p rf transistor amplifier, the second between it and the driver stage. This is not an unusual is used as a combination local- oscil- the driver stage. bias voltage in transistor circuits lator -mixer. A common- emitter circuit There are several reasons for using (remember that bias currents rather configuration is employed. In operation, VOLUME Ll serves as the antenna coil and L2 2N2I7(2) as the oscillator coil, providing feed- 2N2I7 i DRIVER OUTPUT OUTPUT TRANS FROM back between collector and base circuits AF PREAMPLMPL TRANS 8.8 V 2ND I 5K i 2N217 to start and sustain oscillation. DET 6.7V iV . DRIVER with vacuum -tube I 10 6AV When working 1.5 K receivers, it is standard practice to RI-b + check the operation of a local oscillator by checking for a negative bias voltage across the oscillator's grid resistor. If there is a voltage here, the oscillator is working (although not necessarily at the right frequency). If not, the oscil- TO OTHER lator is dead. STAGES + ON VOL CONT have =100µf 9V 9V A number of technicians tried `` -y q- to use this same technique to check = ON -OFF transistor oscillators, with very un- Fig. 1 -Audio section of the Westinghouse H -602P7 receiver. satisfactory results. 56 RADIO -ELECTRONICS

www.americanradiohistory.com RADIO Since almost all transistor oscillators are class -A (rather than class - C) amplifiers, hase bias voltage remains essentially unchanged whether or not the oscillator is functioning. In practice, the operation of a transistor local oscillator can be checked by using an rf signal tracer or a grid - dip meter, or by applying a substitute CW signal, using a standard rf signal generator. Neutralized stages Old- timers -those to whom the name Atwater Kent brings up per - sonal memories -may sense something strangely familiar about the if amplifier circuit in Fig. 3. This circuit, used in the Truetone D3716A superhet receiver, has a p -n -p transistor in the common- emitter configuration. Its familiar (to old- timers) characteristic is the use of a feedback capacitor (C) between output and

I FT 4 FROM -40µµf 2.511

CONV 1T TO 2ND DET C -6V IR -4V Bench setup for checking transistor radios. A continuously 2.2 R adjustable power supply is a -.25V great convenience. -6V .047 470

AVC = IF= 455KC I Fig. 3- Typical transistor if stage. Cir- cuit is used in Truetone's D3716A receiver. input circuits for stage neutralization. The signal fed back through this capacitor cancels the signal coupled back through the transistor's interelectrode capacitances and stabilizes circuit operation, minimizing the chances of oscillation. Since the feedback capacitor neutralizes the effects of the transistor's interelectrode capaci- ties, its value, of necessity, depends on the characteristics of the transistor used. In the early days of radio, when triodes were the only available tubes, Aligning an all- transistor receiver. Techniques are neutralized rf and if amplifiers were basically similar to those used with vacuum -tube quite common for the same reason -to receivers, but special refinement may be needed. cancel the effects of signal feedback tuned throughout its band. If a fixed On closer inspection, there appears due to interelectrode capacitances. But capacitor is used for neutralization, to be a surplus diode in the receiver just as neutralization techniques fell you may have to replace it whenever connected between the if amplifier's into disuse with the introduction of the the transistor is changed. Some manu- collector electrode and the lower end of tetrode and pentode, so are neutralized facturers furnish a matched set of R5. While seldom, if ever, found in transistor rf (and if) amplifiers be- transistor and capacitor for replace - vacuum -tube receivers, such diodes are coming less common with improvements nient purposes. encountered frequently in transistor in transistor construction and refine- radios. They may be used in the if ments and advances in transistor cir- Extra diodes stages of some sets, in the antenna circuit design. At first glance, the schematic dia- cuits of others, in the converter or rf Where a neutralized amplifier is gram of the RCA 8 -BT -7J receiver, circuits of still other receivers and, in used, the feedback capacitor may he an shown in Fig. 4, may seem quite con- a few instances, in two or more stages adjustable trimmer, a gimmick made up ventional -and it is, as far as tran- simultaneously. of two short twisted lengths of insu- sistor receivers go. This diode serves as a signal limiter, lated wire or a fixed ceramic or mica This broadcast -band superhet uses automatically varying stage loading capacitor. If an adjustable trimmer or four p -n -p transistors in common - (and hence stage gain) with changes gimmick capacitor is used, its adjust- emitter circuit configurations. A 2N140 in signal level, preventing overload on ment should be checked whenever the serves as a converter, a 2N139 as an if strong signals while maintaining maxi- receiver is aligned or whenever it is amplifier, a 2N109 as an audio ampli- mum stage gain for reception of weaker necessary to replace the transistor used fier and, finally, a second 2N109 as the stations. in the neutralized stage. In general, output amplifier. A crystal diode serves The function of the diode is to in- the feedback capacitor is adjusted to as the receiver's second detector. Oper- crease effectiveness of the receiver's ave eliminate any tendency toward oscil- ating power is supplied by a single circuit, and is necessary because the lation and squealing as the receiver is 9 -volt battery. transistor has a narrower range of

AUGUST, 1959 57

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27 -mc converter puts any broadcast receiver on the Citizens band. And it takes only one tube

By J. H. THOMAS

FCC, in its latest change of to make sure others could duplicate transformer from ground to avoid part 19 of the rules governing them. grounding the chassis to the ac line. Citizens band communication, has Fig. 1 shows the converter's circuit The power supply in the diagram de- THEassigned a number of channels in and details of coil construction. The livers around 300 volts. You can use the 26.895 -to 27.225 -mc band for AM coil slugs are cut from 1/4 -inch copper this or reduce it to 200 with a larger voice transmissions. As a direct result, rod (sold in hardware stores for holding filter resistor. there is a lot of renewed interest in up tank toilet floats). These are sol- In automobile sets, you can also tap this type of communication. Many who dered to No. 4 brass screws that have the voltages from the receiver, or build previously shied away from the com- their heads filed flat. Make sure you a separate power supply for the plate plications of the 465 -mc band can now center the head of the screw accurately. voltage. A suitable transistor supply go to work with much simpler equip- [Cambridge Therxnionic Corp. (CTC) was shown in the July, 1958, issue ment. type LS3 coil forms with type 2018 -C of RADIO -ELECTRONICS (page 51). If To receive 27 me on any home or car brass slugs will simplify construction you have a 12 -volt system in your car radio all you need is this simple little and mounting. Editor] with a negative ground, the circuit 1 -tube superhet converter. Most of the If you have an ac home receiver, you can readily be adapted for use with parts can be found in the average junk - can tap heater and plate voltages from one of the new 12 -volt auto radio tubes. box, or even made from readily avail- it. If you want to use a series heater Only one resistor has to be changed, able materials. For example, I got the set (ac -dc), you must build a separate as shown in the diagram. Construction coil slugs from some obscure piece of power supply (see Fig. 2) and lift the offers no problems, as long as rf trans- well corroded surplus, but made some secondary of the converter's output if former T1 is well shielded from oscil-

IIImIIIm1111IIIIIIIII!illllllllllll!;IIII!IIIC

Transistors . . . fact and fiction (continued) effective gain control (with bias varia- going avc signal would be used to as a voLLmr. control, but as part of the tions) than the vacuum tube. reduce the (normal) positive bias used base biasing network (along with R2). A word about the ave circuit may be with these units. The circuit arrangement used main- appropriate. Note that the second de- To someone experienced in vacuum - tains the steady bias needed for proper tector diode is connected so a positive - tube circuitry, the receiver's VOLUME circuit operation as the receiver's going signal is developed with an in- control, R1, may appear to be connected volume level is shifted. IST IFT PHONE JACK DET 6.5a 5.6 K ANT nCOIL 2N140 OSC CONV 2N139 2N109 DRIVER -2.5V 2N109 OUTPUT IF COIL -8.5V AMPL AFAMPL -7V TRANS I I OUTPUT_o 5V T RI TRANS ii 4.90 8 C4 II -8V 2 °d I 2.6 R ,--1 1 .02= 10 ` E .i1 -2.I V -2.3V Z .03 -2.4V .005 Tr r -2.2V i 4451° R5 .0°Q d I -2.1V -2.I ° 120 S1 VOLUME % i ¡ J w 1.2K , 390 51 I20n .1 4'25 22051 .6d1. son , I 5% 5% / IK =.03 33K 18K R2 -- 5% 5% 4.7 K IK % 10051

1K \ +=100pf IF=455KC o - 0OFF Fig. 4- Circuit of RCA's 8- BT -7J, an all- transistor receiver. crease in signal level. This tends to in reverse. The hot audio signal ob- Transistor circuitry only means that reduce the transistors' normal bias and tained from the driver transformer is the technician who has a good under- thus to reduce amplifier gain (in con- coupled through C4 to the volume con- standing of it in terms of semiconduc- trast to vacuum -tube circuits, were bias trol's center arm, while the control tor (rather than vacuum -tube) opera- voltage is increased to reduce gain). If itself is connected between the output tion should have little or no difficulty in n -p -n transistors were used in the if amplifier's base electrode and circuit analyzing the somewhat unconventional and rf amplifier stages, a negative- ground. Actually, R1 serves, not only circuits he may encounter. END

58 RADIO- ELECTRONICS

www.americanradiohistory.com RADIO

The few parts needed and careful arrangement Small size makes the convert r ideal make converter a small unit. for auto installations,

TO ANT V M!(ER-OSC - WARNING: The author used a four -terminal 6BE6 16V HTR, 200V PLATE) 1t jack for power input. This means that the plug 128E6 (12V HTR, 200V PLATE 1 from the power supply is hot {up to 200 COAX 12AD6 (12VHTR,I2VPLATE) TO RCVi2 SEE COAX volts). For safety, use a plug or the con- ANT POST verter chassis as indicated in the schematic TEXT ¡ T2 and parts list. OUTPUT TRANS TI P2 I_ VPI COPPER- SLUGGED 2 CE real' ANT TRANS helpful when making the adjustments. -ot= DISCONNECT '=ROM GND B BRING OUT Fig. 3 shows how to connec- the con- rte 15µ8.f R2 LI LEAD FOR AC/ DC ANT i - CI 20µµf 22K verter to ac -dc receivers that have loop COIL 200v1 or ferrite antenna coils. 4T I OR FOR 12V USE The converter is so comp.t it that it 12 V p3 L2 4.7 K FOR R2 can be installed almost anywhere in 18T 60R12V car. you want it out of sight, mount t/ ONO If I TO HTR _L it behind the dash. You can include a T3 switch to transfer the antenna. Be sure COPPER - SLUGGED OSC TRANS HTR PINS -354 you use the same kind of coax cable COPPER SLUG throughout or you will pick up ignition I /4" LNG, I /4 °DIA interference. There will be more of this

RI- 22,000 ohms, 1/2 watt on the shortwave bands than on the R2- 22,000 ohms, 1/2 watt (with 12 -volt 13-plus use broadcast band anyway and. if you do 4,700 ohms) PLASTIC PLUG CI -15 µ{sf, ceramic I THREADED) not have spark suppressors, you may 02--32 µµf, ceramic have to install some. C3 -20 µµf, ceramic C4 --.01 µf, ceramic CHASSIS Since auto receivers are generally C5- 83-200 µµf trimmer very sensitive and have good image re- An capacitors 600 volts SPRING BRONZE 71- antenna transformer: LOCK NUT jection, you'll find this simple converter 11 -4 turns No. 34 enameled on cold end of L2 COIL. MOUNTING gives you a very "hot" 27 -mc receiver, 1.2 -18 turns No. 34 enameled on 343-inch outside diameter form with ad ¡ustable copper slug, V-6BE6 or 1213E6 or 12AD6 callable of receiving the 5 -watt maxi- V inch OD, '/4 inch long. JI, 2 -phono jacks mum T2- miniature broadcast oscillator transformer PI, 2 -phono plugs signal from over surprisingly long T3-oscillator transformer; 20 turns of No. 34 enam- P3-4- terminal male connector distances. We've heard then: intelligibly eled on same type form as TI, close wound. Antenna, cut for I I meters 15 ENn Tapped at t5 turns. Miscellaneous hardware from as far as miles. Fig. 1- Circuit of the 1 -tube unit. lator transformer T3. I used the little and 1,600 ke, wherever there is a quiet piece of aluminum that holds up the spat On the dial in your area. However, tube socket as a shield (see photo). by changing the adjustment of T3, you Using an oscillator coil for the if can make the signal come in at any transformer makes it necessary to re- point on the broadcast dial. tune the converter for whatever set it The coils as shown will tune over a be is range of almost 3 nsc. The rf trans- will used with since the coupling CONNECT TO very tight and the receiver's impedance former is tuned for the desired channel BOTH ENOS OF may change the tuning of the trans- (listed in Table I) and T3 to a frc- 16 SECONDARY 1,600 lcc above or below the former some. The values shown for luency CEMENT 2 TURNS OF WIRE I found a grid -dip oscillator TO LOOP FRAME coils and transformer are intended to rf setting. f produce an output signal between 1,000

SEL REGT 12 ) CITIZENS BAND FREQUENCIES (MC) 130V 20 MA 4 -0 6 TURNS 16/150V 4.7K/2W 300 V 26.965 27.035 27.115 27.185 ON C ORE 26.975 27.055 27.125 27.205 + + + l} APPROX pf + 26.985 27.065 27.. 35 27 215 /\ 117 VAC 125 V 27.005 27.075 27.165 27.225 15MA T450 v 27.015 27.085 27.165 27.025 27.105 27.175 ANT b 6.3V/.6ATOHTR Several other f- cnucncies are available for TO IF f contro! ,ionois only. Maximum power input to OUTPUT Fig. plate ;5 6 airs, e.cet,rt for control on 27.255 me 2- Simple power supply for 117 - (only) which can be 30 watts. Fig. 3- -blow to couple the converter to volt ac operation. sic -tle receiverw.' AUGUST, 1959 59

www.americanradiohistory.com ANOTHER FIRST FOR HEATHKIT ... amplifier power rating standards Heathkit is accustomed to pioneering ... to leading the way. We led the way into the kit field of electronic equipment. Now, we are W leading the way to audio amplifier power rating standards . . . standards clearly defined to assure you of Heathkit quality . . . to enable you to compare before you buy. The Heathkit amplifier standards have been established upon these following beliefs after reviewing over one hundred published treatises on the subject: WE BELIEVE any amplifier should be rated for its intended use... PROFESSIONAL amplifiers must be so nearly perfect that no audible change occurs in the program material. HIGH FIDELITY amplifiers must be almost as perfect, almost as efficient. 1. Maximum power at which total harmonic distortion (THD) does not exceed 1.0% at 1000 CPS. UTILITY amplifiers be less can perfect and still fulfill their 2. Maximum power at which total harmonic distortion (THD) practical job. does not exceed 3.0% at 60 CPS. WE BELIEVE the power an amplifier rated of in any of the 3. Maximum power at which total harmonic distortion above "use" (THD) categories should be that power which satisfies all does not exceed 3.0% at 7000 CPS. requirements in that category. 4. Maximum power at which response does not deviate by more Each of the three "use" categories we have chosen has require- than +1 db between 60 and 7000 CPS. ments which can be translated into performance specifications with 5. Maximum equivalent single- frequency power at which in- rather definite limits limits by ... established recognized author- termodulation distortion does not ities. The exceed 3.0% (60 and Heath requirements and their limits for each of the 6000 CPS, 4:1). categories are as follows: We at the Heath Company are now rating all our amplifiers to PROFESSIONAL RATING these standards. To show you just how this 'rating system works, The professional power rating shall be that power which satisfies let's look at the Heathkit EA -3 amplifier: the following five tests: As a professional amplifier - 1. Maximum power at which total harmonic distortion (THD) 1. Maximum Power at which T.H.D. does not exceed 0.3% at does not exceed 0.3% at 1000 CPS. 1000 CPS: 15.1 watts

2. Maximum power at which total harmonic distortion (THD) 2. Maximum Power at which T.H.D. does not exceed 2.0% at ' does not exceed 2.0% at 20 CPS. 20 CPS: 13.9 watts 3. Maximum power at which total harmonic distortion (THD) 3. Maximum Power at which T.H.D. does not exceed 2.0% at does not exceed 2.0% at 20,000 CPS. 20,000 CPS: 15.3 watts 4. Maximum power at which response does not deviate by more 4. Maximum power at which response does not deviate more than +1 db between 20 and 20,000 CPS. than ±1 db between 20 and 20,000 CPS: 17.6 watts. 5. Maximum equivalent single- frequency power at which 5. Maximum equivalent single- frequency power at which in- intermodulation distortion does not exceed 1.0% (60 and termodulation distortion (60 and 6000 CPS, 4:1) does not 6000 CPS. 4:1). exceed 1%: 18.0 watts. HIGH FIDELITY RATING Taking that power which satisfies all five tests, we could rate the -3 The high fidelity power rating shall be that power which satisfies EA for professional use. at 13.9 watts. Its advertised professional the following five tests: rating is a conservative 12 watts. A review of the below why 1. Maximum power at which total harmonic distortion (THD) chart shows the EA -3 is rated at 14 does not exceed 0.7% at 1000 CPS. watts for high fidelity applications, and 16 watts as a utility amplifier. Notice that our specifications 2. Maximum power at which total harmonic distortion (THD) are set at rated power for one or more classifications does not exceed 2.0% at 30 CPS. (when our customers need an amplifier for a particular use, we 3. Maximum power at which total harmonic distortion (THD) believe thay want it to deliver its rated power does not exceed 2.0% at 15,000 CPS. under those particular conditions). Observe that our distortion figures are specified at the limits 4. Maximum power at which response does not deviate by more of the amplifier frequency range as well as at the 1000 than ±1 db between 30 and 15,000 CPS. traditional CPS (the common practice of rating distortion only at 1000 CPS does tell you 5. Maximum equivalent single- frequency power at which in- not what happens throughout the full range of the termodulation distortion does not exceed 2.0% (60 and amplifier). 6000 CPS, 4:1). As an example of how these standards work on several competitive amplifiers, we have prepared the following chart. Notice UTILITY RATING that if the amplifiers did not meet standards at rated output power, The utility power rating shall be that power which satisfies the we have determined the power output where they do meet the following five tests: standards set up under the three categories.

AMPLIFIER COMPARISON CHART Amplifier Heath Standard Rating Maximum Power Output Satisfying: Description Power Power Rating Power Rating Power Rating Power Rating Power Rating and Price Classification (watts) at Test 1 Stds. at Test 2 Stds. at Test 3 Stds. at Test 4 Stds. at Test 5 Stds. Kit "A" Professional Disqualified 8.4 watts 0.02 watts 0.65 watts Disqualified 3.9 watts "12 w. HI FI" High Fidelity Disqualified 9.1 1.3 1.67 Disqualified 5.9 $23.90 Utility 8.6 watts 9.8 8.9 8.6 12.3 watts 11.6 Assembled Amp. Professional 0.3 4.7 0.3 4.8 1.2 4.0 "B" "14 w. HI FI" High Fidelity 1.1 12.1 1.1 5.7 5.3 8.2 $39.50 Utility 7.8 13.2 7.8 12.9 15.8 13.9 Kit "C" Professional 3.6 11.0 3.6 7.5 7.5 6.5 "12 w. HI FI" High Fidelity 8.0 11.8 8.0 11.2 13.4 14.3 $34.95 Utility 11.9 12.0 12.0 11.9 15.0 14.9 Assembled Amp. Professional 3.8 13.2 3.8 14.5 12.0 14.6 " D" "15 w. HI FI" High Fidelity 10.6 14.3 10.6 14.5 18.3 16.3 Benton Harbor 20, __$64.50 Utility 14.7 14.7 14.7 15.0 23.7 17.0 Michigan Heathkit EA -3 Professional 13.9 15.1 13.9 15.3 17.6 18.0 "14 w. HI FI" High Fidelity 15.5 16.2 15.8 15.5 18.3 18.9 $29.95 Utility 16.4 16.5 16.6 16.4 19.0 19.5 ary of Daystrom , Inc. The Heathhit ampli fier power rating standards have been established as fuatf: r assurance to you of the high quality of our products. We will live by these standards until industry-wide standards are established.

60 RADIO -ELECTRONICS

www.americanradiohistory.com NEW EDUCATIONAL ELECTRONIC ANALOG COMPUTER KIT (EC -1)

9 DC operational amplifiers -3 initial condition power supplies 13044343 tßffiC`' from rl OFJWtiìI3di:Ls 6.ïG36'ï the 5 coefficient potentiometers-repetitive solu- ÿ.ssw-tzs HKIT tion oscillator p ! t>U Electronically regulated power supply ti lqeORqTRU óEn` Eg

Filling a multitude of needs in the fields of education HEATHKIT EC-1 and electronics, the model EC -1 puts advanced engineering techniques within easy reach of the average $19995 individual or institution. An assortment of precision components and patch cords are provided for setting up many complex problems. Solutions are read directly on the panel mounted meter or on an external read-out device such as the Heathkit OR -1 DC Oscillo- scope. An informative manual is provided, illustrating operating procedures and basic computer information as well as showing how to set up and solve typical problems. Shpg. Wt. 43 lbs.

NEW 5" DC OSCILLOSCOPE KIT (OR -1) Identical DC coupled vertical and horizontal amplifiers 5ADP2 flat -face CRT -edge -lit graticule Transformer operated silicon diode power supply HEATHKIT OR-1 Offering all the features of a high quality DC oscilloscope, Free Catalog the model OR -1 is ideal as a read -out indicator in com- $11995 puter applications :,s well as many types of testing and development work. Features Over 100 easy -to -build kits are illustrated DC to 200 kc (1 db point) bandwidth, 0.1 V (peak -to -peak) per Chi sensitivity and described In the latest Heathkit cata- (nocalibrated). Normal frequency coverage is from 5 to 50 kc in four overlapping log. If you are among the thousands ranges. Critical voltages are regulated with gas -filled VR tubes. Coupling may be interested in saving one-half or more on either AC or DC as selected by the input attenuatar switch. Many uses in industrial, hi -fi, test, marine, or ham radio instru- educational and medical fields. Shpg. Wt. 21 lbs. ments, send for your free copy today.

COMING SOON! ELECTRONIC ORGAN KIT...

. an instrument that will excite the entire musical world. Engineered to familiar Heathkit perfection, and styled for the most discriminating taste ... yet simple to assemble and priced for the average home. Interested? Send your name and address, we'll rush information as soon as available. No obligation.

HEATH COMPANY BENTON HARBOR 20, MICH. II a spbsidiary of Daystrom, Inc. 1 SHIP VIA Name Parcel Post NOTE: all prices and specifi- o cations subject to change Address Express without notice. Freight City & Zone Enclosed find ( ) check ( ) State Best Way money order. Please ship ,PLEASE PRINT) C.O.D. ( ) QUANTITY ITEM MODEL NO. PRICE On Express orders do not include transportation charges -they will be collected by the express agency at time of delivery. On Parcel Post Orders include postage for weight shown. All prices are NET F.O.B. Benton Harbor, Michigan, and apply to Continental U.S. and Pos- POSTAGE sessions only. 20% Deposit SEND FREE HEATHKIT CATALOG required on all C.O.D. orders. TOTAL

see listing HEATHKITS are also available at your Dealer on next page

AUGUST, 1959 67

www.americanradiohistory.com RADIO Part VII -Fixed stations: Let's see how their transmitters, re- ABC's of ceivers, power supplies are set up MOBILE RADIO 1L2 By LEO G. SANDS ABASE station is a land station used primarily for communi- Electronic communications control console cating with mobile units. A is used for railroad fixed station, a term often operations. erroneously applied to base stations, is a land station used primarily for com- municating with other fixed stations. control unit is connected to the radio A typical mobile radio system has equipment through a multiconductor one base station and a number of mobile cable. units. More elaborate systems may in- Sometimes the base clude two or several base stations. station is identical to a mobile unit. The Kaar TR -500, one, two or more The Erie Railroad, for example, a channels. Frequency has for example, may be used interchange- string of base stations stretching from changing is handled by switching ably as a base station or as a mobile unit crystals or oscillator circuits. The Chicago to New York to provide com- will plete coverage of the since it operate from either 12 volts spread between frequencies must, of entire main line. dc or 117 volts ac. When a base station's radio equip- course, be restricted since the various The radio equipment of a remotely stages must be tuned to a compromise ment is located in the same room as controlled base the person who operates it, station is similar to that to provide adequate performance at all the station used at locally controlled stations. Bas- is known as a locally controlled station. of the frequencies used. When the ically, equipment requirements are the Sometimes, in multichannel operation, operator and the radio equip- same except ment are in for additional apparatus separate transmitters are used for each different rooms or build- which lets the operator control ings, the station is said to be remotely the frequency or pair of frequencies, using transmitter -receiver from a remote a common antenna with switching or controlled. location. There is only one legal control individual antennas for each trans- point, The radio equipment is often mounted whether the is mitter. station locally or re- in a floor or wall motely controlled. The mounting cabinet which An FM transmitter is modulated in person at that can be locked to prevent tampering by point who is in charge of operating one of the early low -power stages, and the unauthorized personnel. Control is ex- radio station is responsible adding an rf booster amplifier does not for the ercised from a remote -control proper operation of unit require any changes in the modulator the base station as through a single -pair telephone line. well as of the associated mobile units. and speech amplifier system. Operation is essentially the same as AM in radio Both types of stations may have one transmitters are used for mobile units (described in III 25 to 55 mc, or more auxiliary control points known Part paging systems operated at as dispatch of this series-April 1959). Communica- in two -way systems operated in the 152 - points. These must be so tion place in one wired the the control takes direction at a 162-mc band and at medium frequencies that operator at time. When transmitting, the operator (1.8 mc) point can prevent use of the transmitter -8.0 and at airports for Uni- uses a press -to -talk button which dis- corn applications from any of the dispatch points if he and airport advisory ables the receiver and causes the in 180 -mc AM is also used deems it necessary. trans- the -134 band. mitter to go on the air. Releasing the in some low -power industrial systems Types of stations button reactivates the receiver and operated in the 25 -50 -mc and 152-162 - shuts off the transmitter. Hence, only mc bands as well as by class -B (465 -mc) .A locally controlled base station ordi- one antenna system is required when and class -D (27 -mc) Citizens' radio sta- narily consists of a transmitter, re- and reception place tions. ceiver, power supply, transmission take antenna system, in the same band. The modulator system of an AM microphone, loudspeaker and controls. transmitter becomes more expensive as A typical locally controlled one is a Transmitters power increases since the final rf stage consolette on a desk, which mounted Medium- and low -power is usually modulated, rather than one houses of the transmitters all equipment except the used base stations are identical the low -power stages. antenna system the at elec- of and microphone. trically (or very similar) to those used Sometimes the transmitter receiver in mobile units. Sometimes the trans- AM modulators power -supply is in assembly placed a mitter is assembled on a panel which Remember when servicing AM trans- relay rack or cabinet. Often a separate fits into a standard 19 -inch relay rack. mitters that the modulation trans- TO MOD Generally, base-station transmitter rf former is a critical component which, RFC RFAMPL TANK output runs from under 1 watt to 60 when operated improperly can con- CKT TI LI watts. Sometimes, for extended cover- tribute distortion and loss of efficiency.

C age, and when permitted by FCC regu- Fig. 1 is a typical modulator circuit. lations, transmitters rated up to 250 Its frequency response and performance C2 C3 watts are used. A 250 -watt transmitter depend upon the values of Cl, C2 and generally consists of a low -power FM C3. Ordinarily, these components are transmitter which drives a 250 -watt selected at the factory to match modula- MOD RFAMPL power amplifier. A heavy -duty power tion transformer Tl. B+ B+ supply is usually provided for the If T1 is ever replaced it may be nec- Fig. 1-Typical modulator circuit used power- output stage. essary to change the value of C2, and in AM transmitters. A single transmitter may be used on sometimes even Cl and C3. Capacitor 68 RADIO -ELECTRONICS

www.americanradiohistory.com RADIO C2 is an audio coupling capacitor which prevents do from flowing through the secondary of Tl. Its value is critical and must compensate for Ti's leakage inductance, which varies from one transmitter to another. The value of C2 affects the transmitter's low -fre- Convenient "over- the -counter" delivery is livery, provides demonstration facilities, quency performance, which is important now available through any of the Authorized offers you a reliable source for parts and when low- frequency tones are used for Heathkit Dealers listed telow. Although you fast service ... and stands ready to cour sel selective calling or tone -squelch opera- will find the price of Heal hkits slightly higher or advise you on any problem that might tion in when buying locally, were sure you'll agree arise. communications transmitters. affect Bypass capacitor Cl must also have that this increase is justified. Your dealer This new service does not dour absorbs all transportation charges, carries continued privilege to buy directly from a specific value, not just have of high a complete stock of kits for immediate de- Heath Company if you prefer. enough capacitance to bypass the audio signal. C3 is also critical and its value NOW READY TO SERVE YOU ... must balance out the reactance of choke Ll at the low- frequency end of the CALIFORNIA MASSACHUSETTS OHIO BAKERSFIELD BOSTON MIDDLETOWN modulation band. Kiesub Corporation Audionics, Incorporated Srepco, Inc. High- frequency response is affected 2615 "F" Street 1348 Boylston Street 2104 Brentwood Avenue BERKELEY MICHIGAN NEWARK by the capacitance to ground (C4) zacKIT Corporation Buckeye Electronics Dist one. 2002 University Avenue ALLEN PARK 114 Union Street Volta Electronics of the rf amplifier and to some extent CHICO PIQUA 6716 Park Avenue Srepco, Inc. by the inductance of the rf choke. At Dunlap Radio & TV 928 Main Street DETROIT R.R. F1, Box 308 High Fidelity Workshop SPRINGFIELD the low- frequency end of the trans- EL CAJON 16400 West Seven Mile Road Tetrad Electronics Standard Radio-Springfield Inc. mitter's rf range, there is generally 182 East Main Street MINNESOTA 1300 S. Paris Road FRESNO ZANESVILLE more capacitance to ground than at the MINNEAPOLIS Buckeye Dunlap Radio E TV Electronics Dist., Inc. Audio King Company 120 South Eighth Street high end, due to the setting of the 2617 Tulare Street 913 West Lake Street BEACH OREGON LONG NEW JERSEY tuning capacitors. This effect is, of Kierulff a Company PORTLAND 1501 Magnolia ATLANTIC CITY Eccles Electric Company course, of considerably more signifi- LOS ANGELES Radio Electric Service Co. 237 Northeast Broadway cance in broadcast transmitters than Bushnell Sound Corp. 452 North Albany Avenue SALEM 12024 Wilshire Boulevard CAMDEN Cecil Fames Company communications transmitters where the Kierulff Sound Corp. Radio Electric Service Co. 440 Church Street, Northeast 5t3 Cooper Street 820 West Olympic Boulevarc PENNSYLVANIA audio response cuts off rapidly above Kierulff MOUNTAINSIDE t Company Federated Purchaser, Inc. A LLENTO W N 6303 E. Corsair 3,000 cycles. 1021 U. S. Route #22 Federated Purchaser, Inc. MARYSVILLE NEWARK 1115 Hamilton Street Dunlap Radio 8 TV. Purchaser, EASTON 5th & "J" Street Federated Inc. Receivers 114 Hudson Street Federated Purchaser, Inc. MERCED 925 Northampton Street Base -station receivers are electrically Dunlap Radio d, TV NEW YORK PHILADELPHIA 234 West 17th Street BELLEROSE Austin Electronics, Inc. identical (or at least similar) to mobile MODESTO Cross Island Electronics, Inc. 1421 Walnut Street units. These fixed receivers are often Dunlap Radio & TV 247-40 Jericho Turnpike Radio Electric Service Co. 419 10th Street BROOKLYN 701 Arch Street assembled on panels which fit standard NATIONAL CITY Acme Electronics, Incorporated Radio Electric Service Co. Telrad Electronics 59 Willoughby Street 3412 Germantown Avenue 639 National 19 -inch relay racks. FARMINGDALE Radio Electric Service CO. ONTARIO Gem Elec. Distributors, Inc. 5930 Market Street In multichannel systems, it is often Kiesub Corporation 34 Hempstead Turnpike 124 N. Benson WILLOW GROVE preferable to use a separate receiver FOREST HILLS Radio Electric Service CO. OXNARD Beam Electronics, Incorporated 29 York Road for each channel, each with its own Kierulff 8. Company 101 -10 Queens Boulevard 508 E. Date Street YORK HICKSVILLE Radio Electric Service Co. antenna, or multiplexed into a common PALO ALTO Gem Elec. Distributors, Inc. 1114 Roosevelt Extension be mon- Zack Electronics 236 Broadway antenna, so all channels can 654 High Street MINEOLA RHODE ISLAND itored simultaneously. A way to mute SACRAMENTO Arrow Electronics, Incorporated PROVIDENCE Dunlap Radio & TV 525 Jericho Turnpike Audionics, Incorporated any of the receivers from the control 1800 22nd Street MT. VERNON 790 North Main Street SAN BERNARDINO Davis Radio Distributing Co Inc. TEXAS is in- 70 East Third Street point when necessary sometimes Kierulff a Company BEAUMONT cluded. 390 South Mt. Vernon NEW YORK Sterling Radio Products, his. SAN DIEGO Arrow Electronics, Incorporated 1160 Laurel Street 65 Cortlandt Street When a single receiver is used for Telrad Electronics BRYAN 3453 University Avenue Harvey Radio Company Sterling Radio Products, Ice. two or more channels, frequency change SAN FRANCISCO 103 West 43rd Street 2615 Texas Avenue Zack Electronics is handled by or 1422 NO. CAROLINA DALLAS switching crystals Market Street Hillcrest Records, Inc. SANTA BARBARA CHARLOTTE 6309 Hillcrest Avenue oscillator circuits, depending upon the zacKIT Corporation Southeastern Radio Supply Co. 513 1200 W. Morehead Street HOUSTON technique used by the manufacturer. State Street Sound Equipment, Incorporated STOCKTON GREENSBORO 2506 Crawford Street Dunlap Radio A TV Southeastern Radio Supply CO, 27 North Grant Street 404 N. Eugene Street HOUSTON Power Supply Sterling Radio Products, Icc. TARZANA FAYETTEVILLE 1616 McKinney Avenue Sometimes, as in mobile units, a Valley Sound Corp. Southeastern Radio Supply Co, 18841 Ventura Boulevard 525 Street LUFKIN Gillespie Sterling Radio Products, Ice. common power supply serves both the VAN NUYS KINSTON 428 Atkinson Street Kierulff ó Company Southeastern Radio Supply Co, transmitter and the receiver. Since 14511 Delano 408 N. Heritage Street VIRGINIA is base VISALIA RALEIGH ARLINGTON more space available at stations, Dunlap Radio & TV Southeastern Radio Supply Co. Key Electronics, Inc. separate power supplies are sometimes 1725 Mooney Avenue 414 Hillsboro Street 126 South Wayne Street DELAWARE OHIO WASHINGTON used. SEATTLE The both WILMINGTON CHILLICOTHE Seattle Radio Supply, InC. performance of the trans- Radio Electric Service CO. Buckeye Electronics Dist., Inc. 2117 Second Avenue Third & Tatnall Streets 565 North High St. mitter and receiver can be adversely WISCONSIN FLORIDA COLUMBUS affected by large variations in input COCOA Buckeye Electronics Dist., Inc. MADISON Thurow Distributors, Inc. 236 -246 East Long Street HI -Fi Corner 401 State Street voltage. These effects can be counter- 540 St. Johns Street DAYTON acted by installing a voltage regulator MIAMI Ham 'N HI -Fi, Inc. Satterfield Electronics, Inc. Thurow Distributors, Inc. 826 North Main Street 1900 South Park such as a Sola transformer or a Curtiss - 1800 Northwest 23rd Street Srepco, Inc. MILWAUKEE 314 Leo Street Hi -FI Center Wright ac voltage regulator, which LOUISIANA HAMILTON 4236 West Capitol Drive LAFAYETTE Srepco, Inc. Netzow's compensate for wide variations in line Sterling Radio Products, Inc. 145 Highland Avenue 2630 North Downer Avenue voltage and load. They are often well 1005 Cameron Street MARYLAND worth their cost in increased tube life Careful selection of reliable qualified dealers is a slow SALISBURY alone, let alone improved performance. Radio Electric Service Co. process ... so please bear with us if your area has nett A communications system has no 736 South Salisbury Boulevard been covered. Thank you. value if it is not working. Power failure can disable a base station, and usually HEATH C A Subsidiary Strom, Ina. happens when communication is most Benton Harbo urgently needed.

AUGUST, 1959 69

www.americanradiohistory.com RADIO

AC TO RADIO EQUIPMENT CONTROL -3( LINE UNIT TERMINATION UN T ALTERNATOR zw DC MOTOR IL 71 AC MOTOR AUDIO zw AUDIO I 111

PRESS- 1 L BAT PRESS TO -TALK ; RELAY COIL a

CONTROL LINE R UNIT NATION UNIT

BATTERY II CHARGER BATTERY AUDIO n 0 - a AC FROM I1L=- PRESS -TO -TALK PRESS l CHANNEL- LINE + S. - o TO CHANGE Fig. 2 -Power supply provides continuous ac power even if line power fails TALK- BATTS RELAY 'i IIp COILAY 1L-0 o off COIL II A gasoline- engine -driven alternator Fig. 3 -Four methods for remote con- + - CHANNEL CHANGE - 6 a with an automatic starter is a good trol over single pair of lines: a -sinr CONTROL LINE power plex; composite (two- function sim- UNIT TERMINATION standby source. The standby b- -1 generator takes over in case plex); c- metallic loop; d- metallic of power loop, current differential. failure, shutting itself off when utility w is II power restored. control unit which lets the operator -71 AUDIO w (AUDIO In some cases continuity of operation control the radio station over a single - 1-3 is so important that the time required pair telephone line is preferred. il 1111 a for a gasoline engine to start cannot Fig. 3 shows four popular methods be tolerated. A battery bank and a for remote control over a single pair. vibrator type converter may be used as In Fig. 3 -a, the circuit is simplexed to PRESS- + - S. TO -TALK a standby power source. Delay is then ground. When the press -to -talk switch RELAY only momentary since the vibrator is closed, do flows BATT PRESS -TO -TALK COIL through both line e starts functioning as soon as the chokes, both legs of the line, both halves CONTROL changeover relay applies power to it. of the line transformer of the line UNIT TERMINATION Continuous power, with no inter- termination unit and through the relay TN T ruption at all, can be provided by a coil to ground and back to the line con- continuous power generator, such as trol- voltage source (shown as a battery z ; II F. J those developed by Bogue Electric for simplicity). AUDIO z E. Manufacturing Co. This consists of an In Fig. 3 -b, two functions are per- ac motor, ac generator and a do motor formed. The line is split by capacitors coupled as shown in Fig. 2. at each end, preserving the ac relation- IiJI IEL The radio equipment always receives ship but dividing the line into two do its power from The ac generator, which circuits. When the press -to -talk button is ordinarily driven by the ac motor. is closed, do flows through one choke, III When utility power fails, relay RY is one side of the line, one winding of ill' co, PRESS TO- CHANNEL- de- energized and its contacts connect the line transformer at the far end, CHANGE the do motor to the battery. This hap- through the relay coil and back to the RELAY COIL RELAY 4 (25 MA) COIL pens so quickly that no power inter- control point through ground. When the ó ruption occurs. When power is restored, channel- change switch is closed, the relay RY is energized and cuts off the same thing happens through the other PRESS-TO-TALK d battery. The battery is kept charged by side of the circuit. Either or both cir- a battery charger, powered from the cuits can be operated, sequentially or Í Bendix Radio ac line. simultaneously. Dependence upon ground as a return press -to -talk relay at the far end but Controls circuit can be avoided by using the is bypassed around the coil of the Control of a transmitter receiver circuit shown in Fig. 3 -c. Here, when channel -change relay by the rectifier. combination may be extended by length- the press -to -talk button is closed, do When set for channel 2, the polarity ening the leads from the microphone, flows through one choke, one side of of the energizing power source is re- loudspeaker, press -to -talk switch and the line, one half of the line trans- versed. Now both relay coils are ener- frequency- selector switch (when used) former primary, the relay coil and back gized since the rectifier across the to the radio equipment. As many as 11 through the other half of the line trans- channel -change relay coil opposes the conductors are required, and the two former primary, the other side of the flow of current, which must now flow microphone leads should be shielded. line and the other choke to the press - through the coil instead of around it. Separation between radio equipment to -talk switch. Fig. 4 is the circuit of a Bendix and control point is obviously limited The circuit shown in Fig. 3 -d is used MS -289B line termination unit. Trans- because of the losses in the lines as to control two functions without re- former T101 is the line transformer well as by the possibility of hum pickup quiring ground as a return circuit. shown in Fig. 3. When relay K101 is by the microphone leads. When the When set in channel 1 position and energized, the secondary of the line control point is a significant distance when the press -to -talk button is closed, transformer is switched from the re- away from the transmitter, a remote- current flows through the coil of the ceiver's audio output to the trans- 70 RADIO- ELECTRONICS

www.americanradiohistory.com RADIO mitter's microphone input. Another COMMUNICATION UNAT pair of contacts closes the circuit which PUSH -TO -TALK CKT controls the relays that disable the re- COMMUNICATION UN7- ceiver and energize the transmitter. PUSH -TO -TALK SOURCE The fixed pad consisting of R106, COMMUNICATION UNPT R107, R108 and R109 attenuates the AUDIO OUTPUT 500F60C O audio signal level to approximately 0 db. However, it does not load the re- TELEPHONE ceiver output and, unless a speaker is LINE connected to the receiver, a resistive COMMUNICATION UNIT load should be added. T -pad R101 per- MIKE INPUT CKT mits setting the audio input level to the transmitter to the desired level. PUSH -TO -TALK RELAY relay COMMUNICATION UNIT For two -channel operation, CHANNEL CHANGE SOURCE K102 is added. When energized, it closes COMMUNICATION UNIT the circuit controlling the frequency - CHANNEL CHANGE CKT change relay. SEE CONNECTION Fig. 5 is a block diagram of one type DIAGRAMS OI of remote control unit. When relay RY 2 by closing the press -to -talk CHANNEL RELAY = is energized [3. 3 switch, the line transformer is dis- K 102 J o- connected from the input of the receive 4 to the output amplifier and connected 5 of the transmit amplifier. Another o ¡ ` pair of contacts applies do to the center J FOR METALLIC FOR CONNECTION FOR tap of the line transformer. This ener- LOOP OPERATION COMPOSITE SIMPLEX PUSH-TO -TALK OPERATION OPERATION gizes a relay at the far end, switching ONLY the remote station to receive. Fig. 4- Bendix MS -289B line- termination unit. Most remote- control units are designed for use with radio equipment the line. The output is generally set at Fig. 5 -Brock dia - of the same make. Others are designed 0 db equals 6 mw. An automatic gain grain of remote- for use with any make of radio equip- control compensates for microphone TRANSMIT control unii. ment. output variations up to 20 db. The input AF AMPL The complete Kaar 117C903 remote - signal from the base-station receiver may be as low as -20 db equals 6 mw control system consists of a remote SPKR INE TRANS control unit and a switching -line am- for a full 1 -watt rated output to the a dynamic microphone with built -in speaker or 0.8 watt each to the plifier plus LINE desk stand. This system makes it pos- built -in speaker and one external sible to select any one of three trans- speaker. This control system is intended - mitters or channels, switch line power for use with lines up to 20 miles long. to the base station on or off, and adjust The multiple control functions are of by applying different pos- the squelch setting of a remote receiver taken care PRESS -TO -TALK as well as amplify audio in either di- itive dc voltages to one or both sides rection and reproduce the audio signal of the telephone line. At the base - from the distant receiver, all over the station end of the line, the dc is applied same pair of wires. to one or more relays in the switching - fed to the receiver squelch which is The switching -line amplifier, which line amplifier. These various relays pull of Rl. This hence can controlled by adjustment fits into a standard 19 -inch relay rack, in at different currents and low voltage does not affect relay RY2. is installed at the radio station adja- be energized selectively. When press -to -talk switch S1 is cent to the transmitter (s) and receiver. A unique feature of this remote - RY1 is energized and a to the closed, relay Its amplifier provides up to 40 db of control unit is its ability control 105 volts dc is applied to The sim- positive gain of audio signals from the remote squelch of a distant receiver. the line. This forces enough current 6 how control and dispatch points and delivers plified schematic in Fig. shows through relay RY2's coil to energize up to 12 db above 6 mw. this is done. In "receive" condition when negative it' and turn on the transmitter. The remote -control unit, which is ob- relay RY1 is de- energized, a Next month we will look into another from 0 to 20) is viously installed at the control point voltage (adjustable remote -control system. Then a brief 1 one winding as well as at additional dispatch points, applied to line through study of antennas, transmission lines, delivers up to 14 db above 6 mw to of Tl. At the far end, this voltage is relay stations and Conelrad will bring this series to an end. TO BE CONTINUED

LINE 1 TI T2

AUDIO AUDIO Vibrator type converter used with storage battery forms a standby ac power SQUELCH TO RCVR supply for a base sta- CONTROL SQUELCH tion. A Cornell -Dubi- lier unit. RI S SI RY 2 -20V BAT T Fig 6- Simplified 105 V schematic shows + - TRANSMIT - TRANSMITTER how squelch is con- RECEIVE KEYING trolled remotely. RELAY RELAY 71 AUGUST, 1 9 5 9

www.americanradiohistory.com SUPERIOR'S NEW MODEL 77 SUPERIOR'S NEW MODEL TV -50A

VACUUM TEE VOLTMETER GENOMETER WITH NEW 6" FULL -VIEW METER 7 Signal Generators in One! Compare it to any peak -to -peak V. T. V. M. made R.F. Signal Generator for A.M. by any other manufacturer at any price! R.F. Signal Generator for F.M. Uses new improved SICO printed cir- Audio Frequency Generator cuitry. Employs a 12AÚ7 as D.C. amplifier and two 9006's as peak -to -peak Marker Generator voltage rectifiers to assure maximum sta- Bar Generator bility Meter is isolated from the measuring circuit by a balanced push -pull Color Dot Pattern Generator amplifier. Uses selected 1 °ó zero tem- Cross Hatch G ator perature coefficient resistors as multipliers. This Versatile All- Inclusive AS DC GEN- A VOLTMETER: The Model 77 is ERATOR Provides ALL the Outputs indispensable in Hi -Fi Amplifier servicing for Servicing: - rte= and a must for Black and White and color TV Receiver servicing where circuit Model TV- 50A- Genometer A.M. RADIO BLACK AND WHITE TV loading cannot be tolerated. Total Price $47.50 F.M. RADIO COLOR TV Model 77- Vacuum Tube Voltmeter Terms: 511.50 after 10 day trial, AS AN ELECTRONIC OHMMETER: AMPLIFIERS Total Price then 56.00 monthly for 6 months $42.50 Because of its wide ronge of measure- if satisfactory. Otherwise return, Terms: $12.50 after 10 day trial, ment leaky capacitor, show up glar- no explanation necessary, R. F. SIGNAL GENERATOR: 100 Kil- then $6.00 monthly for 5 months ingly. Because of its sensitivity and ocycles to 60 Megacycles on funda- if satisfactory. Otherwise return, low loading, intermittents are easily mentals and from 60 Megacycles to no explanation necessary. found, isolated and repaired. 180 Megacycles on powerful BAR GENERATOR: Pattern consists harmonics. of 4 to 16 horizontal bars or 7 to 20 AS AN AC VOLTMETER: Mea- vertical bars. VARIABLE AUDIO FREQUENCY SPECIFICATIONS GENERATOR: Provides sures RMS value if sine wave, a variable DC VOLTS -0 to 3/15/75/150/300 /750,x1,500 DOT PATTERN GENERATOR (FOR 300 cycle to 20,000 cycle peaked volts at 11 megohms input resistance. AC and peak -to -peak value if com- COLOR TV): The Dot Pattern pro- wave audio signal. VOLTS (RMS) -0 to 3/15/75/150 /300/750/ plex wave. Pedestal voltages jected on any color TV Receiver tube 1.500 volts. AC MARKER GENERATOR: The follow- VOLTS (Peak to Peak) -0 to that determine the "black" by the Model TV -50A will enable you 8/40/200/400/800 /2,000 volts. ELECTRONIC to adjust for proper color convergence. ing markers are provided: 189 Kc.; OHMMETER -0 to 1,000 ohms /10.000 ohms/ level in TV receivers are easily 262.5 Kc., 456 Kc., 600 Kc., 1000 Kc., 100,000 ohms /1 megohm /10 megohms /1011 read. CROSS HATCH GENERATOR: The 1400 Kc., 1600 Kc., 2000 Kc., 2500 Kc., megohms /1,000 megohms. DECIBELS -10 pattern consists of non- shifting hori- 3579 Kc., 4.5 Mc., 5 Mc., 10.7 Mc., db to 4- 18 db, 4- 10 db to -f- 38 db. 30 db to + zontal and vertical lines interlaced to (3579 Kc. is the color burst frequency.) .4- 58 db. All based on 0 db - .006 watts (6 mw) Complete with oper- provide into e 500 ohm line (1.73v). ZERO CENTER ating instructions, a stable cross -hatch effect. METER - Por discriminator alignment with full probe. leads. and scale range 0 of to 1.5/7.5/37.5/75 /150/375/750 rase. 110 -I ill volt 60 The Model TV -50A comes complete with shielded leads and 1 I volts at 11 megohms input resistance. cycle. Only .*4250 operating instructions. Only ii "

sI PI: It IUIt'eS RCA RADIATION COUNTER Nts Mone t. 5JPER METER MADE TO SELL FOR $160 OFFERED fOR ONLY $ - 4750 WITH NEW FULL -VIEW METER .- (Muth lw thon tor, 6" of Manufacture.) NET - , eamge.rQIl4K Endless experiments and dis- INDICATES coveries in the new exciting field VOLT -OHM MILLIAMMETER RADIOACTIVITY of nuclear energy are made pos- IN 3 WAYS! sible when you acquire this P4,4 finely built and engineered de- CAPACITY, REACTANCE, 1 -BY NEON vice. In the past, a rugged 1-BY PHONE counter which was suitable for INDUCTANCE, AND the prospecting of 3 -BY METER radio -active ores such as uranium, thorium DECIBEL MEASUREMENTS and radium, was unsuitable for laboratory work due to the in- SELENIUM AND SILICON ability of com- Model 79 -Super Meter bining accuracy Total Price $38.50 RECTIFIERS, SILICON AND with ruggedness. Terms: $8.50 after 10 day trial, GERMANIUM DIODES. Conversely a lab- then 56.00 monthly for 5 months oratory counter, while being ex- if satisfactory. Otherwise return, The model 79 represents 20 years tremely sensitive, could not with- no explanation necessary. of continuous experience in the de- stand use in the field where it sign and production of SUPER - RCA Radiation Counter would be subjected to abuse and SPECIFICATIONS: METERS, an exclusive SICO development. It includes not Total Price ...... _._ ...... $47.50 abnormally hard knocks. only every D.C. VOLTS: 0 to 7.5/15/75/150/750 /1.500. Terms: circuit improvement perfected in S11.50 after 10 day trial. In the laboratory where determin- A.C. VOLTS: 0 to 15/30/150/300/1,500 / 20 years then of specialization but, in 56.00 monthly for 6 months ation of intensity (counts) of a 3,000 D.C. CURRENT: 0 to 1.5 /15 /150 Ma. addition includes those services if satisfactory. Otherwise return, reading are necessary, 0 to 1.5/15 Amperes RESISTANCE: 0 to which are "musts" for properly no the WF- 1.000 /100,000 Ohms, 0 to 10 Megohms. explanation necessary. servicing the ever -increasing num- 11AWB provides sensitivity for sur- CAPACITY: .001 to 1 Mid., 1 to 50 Mid. passing many laboratory counters. REACTANCE: 50 to 2,500 Ohms. 2.500 ber of new components used in all phases of today's electronic SPECIFICATIONS Ohms to 2.5 Megohms. INDUCTANCE: .15 pro- switch to meter reading for exact to 7 Henries. 7 to 7,000 Henries. DECI- duction. For example with the measurements. Decontamination BELS: to +14 to +38, +34 to +58. Employs the extra sensitive 6306 Bis- -6 +18, Model 79 SUPER -METER you can easy with damp cloth applied to the measure muth Type Geiger Counter Tube. Sen- weatherproofed aluminum case. A The following components are all the quality of selenium sitivity is .015 Roentgens per hour radioactive specimen is included for tested for QUALITY at appropriate and silicon rectifiers and all types (1 MR /HR =6600 counts per minute) instrument checking and experiment,. test potentials. Two separate BAD - of diodes -components which have Three counting ranges: 0- 200/2,000/ Included at no extra charge-U. S. GOOD scales on the meter are used come into common use only within 20,000 counts per minute. Handy Atomic Energy Commission booklet. for direct readings. the past reset button. Ideal for survey work five years, and because titled "Prospecting with a Counter." All Electrolytic Condensers this latest SUPER -METER necessar- because the complete unit weighs only R.C.A. Model WF -11AWB come, from 1 5tí lbs. Sight and sound MFD to 1000 MFD ily required extra meter scale, SICO indications complete with self -contained batteries All Selenium Rectifiers. by neon gashes and headphone. Then which 'provide over 200 hours of inter- used its new full -view 6 -inch meter. when un indication All Silicon Rectifiers. is obtained you mittent operation. All Germanuim Diodes. All Silicon Diodes. Comes with complete set of batteries, carrying strap, head- a475o 3850 phone, radio -accise specimen and A.E.C. booklet. Only... Model 79 comes complete with operating instructions, test leads, and steamlined carrying case. Use It on the bench-use it on calls. Only lit EXAMINE BEFORE YOU BUY! USE APPROVAL FORM ON NEXT PAGE 72 RADIO -ELECTRONICS

www.americanradiohistory.com SUPERIOR'S NEW MODEL TW -11

PROF SSIONAL TUBE TESTER * Tests all tubes, including 4, 5, 6, 7, Octal, Lock -in, NOISE TEST: Phono -jack on front panel for p ecic ing in Hearing Aid, Thyratron, Miniatures, Sub -miniatures, No- either phones or external amplifier will dese<- micro - vals, Subminars, Proximity fuse types, etc. phonic tubes or noise due to faulty elements ore loose * Uses the new self -cleaning Lever Action Switches for internal connections. individual element testing. Because all elements are numbered according to pin- number in the RMA base numbering system, the user can instantly identify which EXTRAORDINARY FEATURE element is under test. Tubes having tapped filaments and SEPARATE SCALE tubes with filaments terminating in more than one pin FOR LOW -CURRENT TUBES Previ- on tube are truly tested with the Model TW -11 as any of the pins ously, emission -type testers, it has been sandard may be placed in the neutral position when necessary. practice to use one scale for all tubes. As a result, the The Model TW -11 does not use any combination type calibration for low- current types has been restricted to a * small the Model TW -11 -Tube Tester sockets. Instead individual sockets are used for each portion of scale. The extra scale used here greatly Total Price ...... $47.50 type of tube. Thus it is impossible to damage a tube by simplifies testing of low -current types Terms: $11.50 after 10 day trial, inserting it in the wrong socket. then $6.00 monthly for 6 months * Free -moving built -in roll chart provides if satisfactory. Otherwise return, complete data for all tubes. All tube listings The Model TW -11 operates on 105 -130 Volt 60 Cveles A.C. no explanation necessary. Comes housed in a beautiful hand- rubbed oak cabinet printed in large easy -to -read type. complete with portable cover. $4750

SUPERIOR'S NEW MODEL 82A Multi- Socket Type TUBE TESTER SPECIFICATIONS Production of this Model was de. TEST ANY TUBE IN Tests over 600 tube types layed a full year penciller careful Tests OZ4 and other gas -filled tubes study by Superior's engineering staff Employs new 4" meter with sealed air - of this new method of tiring tubes. 10 SECONDS FLAT ! damping chamber resulting in accurate Don't let the low price mtsïead you! vibrationless readings We claim Model 82A will onCperform Use of 22 sockets permits testing all similar looking units which sell for ®Turn the filament selector switch much more and as proof., we offer to position popular tube types and prevents pos- - specified. sible obsolescence to ship it on our examine te:'ore you ®Insert tube into a numbered Dual Scale meter permits testing of buy policy. socket as designated on our low current tubes To test any tube, you sinrly insert chart (over 600 types included). 7 and 9 pin straighteners mounted on it into a numbered soc!æ¢ as desig- Model 82A panel nated. turn the filament :,witch and -Tube Tester OPress down the quality button - Total Price ...... $36.50 All sections of multi -element tubes press down the quality switch - tested simultaneously THAT'S ALL!.Read quality on meter. Terms: $6.50 after 10 day trial, THAT'S Read emission Ultra -sensitive leakage test circuit will Inter -element leakage if stay indi- then $6.00 monthly for 5 months All! Indicate leakage up to 5 megohms cates automatically. if satisfactory. Otherwise return, no explanation necessary. quality direct on bad -good Model 82A comes housed In handsome, portable Saddle- meter scale. Stitched Texon case. Only .. 1650`ate

SUPERIOR'S NEW MODEL 83 C.R.T. TESTER TESTS AND REJUVENATES ALL PICTURE TUBES ALL BLACK AND WHITE TUBES ALL COLOR TUBES From 50 degree to 110 degree types Test ALL picture tubes -in the carton -from 8" to types. - 30" out of the carton -in the 'set !

Model 83 is not simply a rehashed black and white Model 83 will detect tubes which are apparently good C.R.T. Tester with a color adapter added. Model 83 em- but require rejuvenation. Such tubes will provide a pic- ploys a new improved circuit designed specifically to test ture seemingly good but lacking in proper definition, the older type black and white tubes, the newer type contrast and focus. To test for such malfunction, you black and white. tubes and all color picture tubes. simply press the rej. switch of Model 83. If tills tube is Model 83- C.R.T. Tube Tester Model 83 provides separate filament operating volt- weakening, the meter reading will indicate the condition. Total Price ...... - ...... $38.50 ages for the older 6.3 types and the newer 8.4 types. Rejuvenation of picture tubes is not simply a matter Model 83 employs a 4" air -damped meter with qual- of applying a voltage Terms: $8.50 after 10 day high to the filament. Such voltages trial, ity and calibrated scales. improperly applied can the then $6.00 monthly for 5 months strip cathode of the oxide Model 83 properly tests the red, green and blue sec- coating essential for proper emission. The Model 83 ap- if satisfactory. Otherwise return, tions of color tubes individually no explanation necessary. -for each section of a plies a selective low voltage uniformly to assure in- color tube contains its creased life with no danger of cathode damage. own filament, plate, grid and cathode. Model 83 comes housed in handsome portable Saddle Stitched Texon case - s complete with sockets for all black and white tubes and all color tubes. Only.. .. 389 SHIPPED ON APPROVAL NO MONEY WITH ORDER -NO C.O.D.

Try any of the instru- Ì MOSS ELECTRONIC, INC - ments on this or the Model 77 Total Price $42.50 Dept. D -653, 3849 Tenth Ave., New York 34, N. Y. $12.50 within 10 days. Balance facing page for 10 Model I Please send me the units checked on approval. It $6.00 monthly for 5 months. TW -II Total Price $47.50 days before you buy. completely satisfied I will pay on the terms specified $11.50 within 10 days. balance If completely satisfied with no interest or finance charges added. Other- Mod?" TV-50A .Total Price $47.50 $6.00 monthly for 6 inert, then send down pay- wise, I will return after a 10 day trial positively $11.50 within 10 days. Balance cancelling all further obligations. $6.00 monthly for 6 months. ment and pay bal- Model 82A Total Price t36.50 ance as indicated on RCA Radiation Counter Total $6.50 within 10 days. Balance coupon. No Interest Price $47.50. 51 1.50 within 10 $6.00 monthly for 5 months or Finance Charges Name days. Balance $6.00 monthly for 6 months. Added! If not coin Address Model 83 Total Price 538.50 pleetTT satisfied re- Model 79 Total Price $38.50 $8.50 within 10 days. Balance turn unit to us, no I City Zone....State $8.50 within 10 days. Balance $6.00 monthly for 5 moavbs $6.00 monthly for 5 months. explanation neces- All prices net, F.O.S., N. Y. sary. C.

AUGUST, 1959 73

www.americanradiohistory.com RADIO !Discover -fa ` yourself xty Sfiërwobd 'is the most honored line cf high fidelity components in the fieli Sherwood TRANSISTOR HEADPHONE RADIO Tuners (the first ever to achieve sensitivity under 0.3.i microvo,ts) feature: Inter- Channel push, a noise muting system which makes FM tuning easier than ever R Multiple:: Output By HOMER L. DAVIDSON "Feather -Ray" Tuning Eye Automatic`` Frequency Cont-ol Flywheel Tuning. Combine these tuners wit, either of Sherwood's 'mated" stereo amplifier choices; 29+20 watts Dr 36+36 THIS two -stage transistor radio is watts. And onl Sherwood offers all a simple one for training the be- these features: Single /Dull Bass & ginner. It is designed around a Treble Controls Mid -Range Presence sensitive ferrite coil and two CK- Rise Stereo-Mono Function Indicator 722 transistors and fits into a small Lights Phase- Reverse Switch plastic box. The ferrite coil (L1) used Damping Factor selectior. Sherwoc in this simple circuit is the adjustable also offers ether 36 or 60 watt mon- powdered -iron slug type, commonly aural amplifiers, FM Multip ex Adapters used for replacing bad or worn -out an- and a comple :e Decorator -staled line of tenna coils in small table radios. Ad- cabinetry and 3 -way speaker systems justing the slug controls the volume of The Finest in High Fidelity. Sherwo strong stations and increases the vol- Electronic Laooratories, Inc, 4300 N. ume of distant ones. California Avenue, Chicago 12, Iilinoi Around the coil wind 25 turns of No. 28 enameled wire (L2). Tape these windings to the coil. One side of L2 is grounded and the other end fastened to a 3 -foot length of flexible wire with an alligator clip soldered to it. With this setup you can easily clip to the bed springs, outside antenna or over the insulated telephone cord for an outside port for mounting the transistor sock- antenna connection. ets. Plug in the transistors, making Capacitor Cl, a 400 -µµf trimmer, is sure that the red dot is on the proper used to tune in the broadcast stations. end of the socket. A phono jack is A 14 x 1/2-inch brass rod is soldered to mounted on the case. On the same end the original adjustment screw so a knob drill a hole for the headphone cord. It can be used for convenient tuning. should be a tight fit so the small unit A IN34 crystal diode detects the in- will not slide off the cable. coming signal. From here the rectified The radio is easy to operate. Be sure signal is fed to the base of Vl through to check the wiring before trying it out. capacitor C2. The emitter is grounded Place the earphones over your head and and the collector coupled to a transistor plug in the battery. Hook the alligator interstage transformer. clip to an outdoor antenna and trine in Capacitor C3 couples the signal to the station you want. Adjusting the the base of V2. The output of this tran- ferrite coil's slug will vary the volume sistor is fed to the headphones. On local of the receiver. END stations volume is so great that the phones can be set down and the pro- CK722 (2) gram easily heard 2 feet away. ANT T C3 10 1N34 VI V There is only one battery, a 15 -volt c2 c L2 LI D tl + Eveready hearing -aid type. The shell of T TH E a male phone plug is soldered to the CI 400yRf positive end of the battery. Drill a RI R2 270 K small hole through the plug's shell. A PHONES length of wire is slipped through this hole and soldered to the center prong. CK722 -15V The other end of the wire goes to the PHONO JACK FOR BATT CONNECTION negative terminal of the battery. With this arrangement the battery plugs into C2 d C3 25V LI - FERRITE ANT COIL the radio and serves as an on -off switch. The radio is built to fit a 2 x 2 x 3 -inch E B C plastic case. Although any type of con- tainer can be used, plastic is about the RI -470,000 ohms, 1/2 waft easiest material to work R2- 270,000 ohms, 1/2 watt with. Place the CI- 400 -14f trimmer, see text ferrite coil in one corner of the case. C2, 3 -10 -pf 25 -volt electrolytic The 1N34 diode is soldered to D -IN34 diode R1 and J -phono jack placed next to the coil. Then the inter - LI- ferrite antenna coil, see text stage transformer is on TI- interstage transformer (Stancor U113 or put the oppo- equivalent) site side of the coil with capacitor C3 VI, 2-CK722 mounted directly above it. Midget battery, 15 volts Capacitor Cl Alligator clip (I) is soldered as close as possible to the Phono plug terminals of the ferrite coil. Headphones Solder a brass wire to the grounded Circuit of the two transistor radio. It For complete technical details write Dept. RE8 side of the trimmer to be used as a sup- fits in a small plastic box. 74 RADIO -ELECTRONICS

www.americanradiohistory.com ELECTRONICS U__ p rr >r ... Should

take a

The profusion of correspondence school catalogs and the claims they make can be confusing. Here are some pointers on what to look for in them and the best ways to select a mail -order Alma Mater

By BENJAMIN W. TALLMAN

GOING to school by mail" is an tion, you would be wise at least to tions. Most good home study schools accepted and respected method investigate this alternative to home give you the same privilege -again of getting a general or special- study. Though it's often more expensive through Uncle Sam's Post Office. ized education. More people en- than mail -order schooling, it's usually Good correcnondence schools permit roll in so- called "correspondence schools" well worth the difference. Some good students to ask an unlimited number of or "home study schools" every year schools offer both home study and res- questions about things they don't under- than in all the colleges and universities ident training in various aspects of stand. Some extend this "consr_'`äti,,z" combined. electronics. Servito fop a year b'r more afttr the In the electronics field about the ^ti Home study "..331 do, howe:'er, have course is completed, while the graduate dozen national institutiong offer home a couple of big advantages over resident is getting himself established in the study courses; 21.1 the way from basic schools: You progress at your own electronics field. radio to advanced electronic engineer- pace; you arrange your own study Of course, you pay for this indi- ing-and more home study students en- hours; you can "attend" a good school vidualized service-and if you're inter- roll in radio- television -electronics than in a distant city offering training which ested in just a brushup course without in any other subjects. might not be available in your own it, there are schools offering training Should you take a home study course? area. at a lower cost minus this elaborate If so, how do you go about choosing the personal service. But now we're back right course and the right school? How much like a classroom? to the "textbook" approach, and an First, it's important to bear in mind No one has ever really improved on alternative might be to buy a couple that a home study course is necessarily the classroom-and -lab technique of of reliable up -to -date books. only a substitute for "resident" or teaching. So in evaluating a home study Kits and lab work classroom lab study. It's true that you course you'll want to ask yourself : can get as good an education studying How closely does this resemble class- In addition to "lectures" (lesson at home as in the classroom -but don't room teaching? books) and "personal instruction" (mail kid yourself, it's going to be more When you consider that most TV query service), many electronics home difficult. radio correspondence courses cost from study courses have "lab" prog.ams- This is because your only contact $100 to $450, you'll want more than a indeed, they should have in such prac- with your instructors and your school mere textbook or set of books. You can tical courses as TV radio servicing. will be through the United States Post learn by reading a $15 textbook, but Be on your guard when a school claims Office. Therefore, it's going to require you can learn better and quicker from you need no equipment to study elec- a greater expenditure of time and much a textbook plus personalized instruction tronics. It is mighty difficult to learn more self -discipline to learn a given plus lab work. about circuits without actually having j amount studying at home, as compared If you become a home study student, one to trace as you read the printed with the day -to -day personal contacts you will receive one group of lessons lesson material. with instructors and fellow students at a time by mail (plus kits of lab Some of the home training programs in a resident school. parts, if they're included in the course). supply the required laboratory equip- Home study schools came into being At the end of each lesson is a series of ment in kit form. Others rely on the to fill the educational needs of people examination questions to determine how student to buy the needed parts locally. who lived too far from classroom type well you have absorbed the material in The school that includes equipment will, schools or whose hours of work made the lesson. You must send the completed of course, charge considerably rr_ore for it impossible for them to attend "live" examinations to the school for grading its program -but you are assured that classes. before another set of lessons is mailed the equipment you use in training will If you live in an area served by a to you. follow the diagrams and instructions in good electronics school and can arrange So far so good. Just like a classroom the textbooks. However, under certain your time so you can take a day or school. But in a classroom school there's circumstances you may be able to save evening course with personal instruc- one big advantage -you can ask ques- a little on the cost of your equipment

AUGUST. 1 9 5 9 75

www.americanradiohistory.com ELECTRONICS by buying parts "on the outside." dozen at a time. Some have a full A few schools offer their home study 4 -year program. graduates several weeks of resident But be wary of the school that offers nstruction at no extra cost or for a a degree by mail. Most state laws mall additional fee. This is mostly lab prohibit the awarding of degrees for work and is well worth considering if correspondence work. it is at all possible for you to be away from your home and job for the required What about prices? time. This resident instruction privilege The cost of home study training might be the deciding factor in your varies all over the map. Radio TV choice of a school if the location of the electronics technician courses range resident training is accessible and you from about $140 to $450, with equip- can afford to take a couple of weeks off. ment kits. Without kits, they start at Home study schools offer a large $40 and go up to about $200, depending number of "fringe benefits" as induce- on the school. Generally the schools ments to prospective students. Among which cost more offer the student more these are fancy diplomas, job placement individualized instruction, better equip- services, references to prospective em- ment and better lesson materials than ployers and so forth. the cheaper ones. If you want good Nearly every school will do something training, watch out for the real cheapies about helping you get a job. Some have -investigate them thoroughly before elaborate employment bureaus and job you even think of signing on the dotted counseling service. Others merely write line. The old saw, "You usually get letters of reference to prospective em- what you pay for," generally holds ployers whose names you send them. true in the correspondence school field. Don't be dazzled by these extra serv- All home study schools have "pay - ices. Remember, the value of the course while- you -learn" plans -or in simple lies in what you learn. If you know English, time payments. The down pay- your stuff, it will be relatively easy to ment ranges from $5 to $100, with land and hold a job in your chosen field. monthly payments from $6 to $50, But if you don't, an engraved diploma depending on the school and course. and a fancy employment service won't If you choose to pay cash, or to pay conceal that fact from your boss. your tuition in full in 2 to 6 months, you save from 6% to 15% of the Types of courses installment plan cost. A wide variety of home study courses There are some advantages to paying is offered in the electronics field. The on the installment plan, even if you most popular are the basic radioTV have the cash. For example, if you find electronics courses which start with the it necessary to drop the course without assumption that ou don't know an completing it, in some cases it may take electron from a kilowatt and work up a Iong time to get a partial refund after through TV troubleshooting and repair. you have paid your full tuition. Even if you have a basic grounding in If you do drop a course, you won't electronics, this is the course to take get a refund of what the schoeil calls if you want to learn TV radio serv- the "matriculation fee" (usually about icing or to improve your skills as a 15-20% of the entire cost). You also technician. Other basic Courses include must pay so much for each lesson com- the communications field and prepare pleted. Although a few schools stipulate the student for a first -class radio- in their contracts you must pay for the telephone or radiotelegraph license. entire program if you drop the course, This license is a Federal government this is rarely legally enforceable. requirement for technicians working in Several schools charge on a per - TV or radio stations, mobile, shipboard lesson or lesson -group basis -a specified radio and other fields where transmit- amount for each group of lessons or ters are involved as well as receivers. kit of parts, rather than on a flat -fee Several schools offer advanced train- basis for the entire course. ing -that is, the program is designed You proceed with your lessons at for the man who already has extensive your own pace in home study. Schools experience in electronics. If you have allow you to advance as fast as you the training, they can teach even the wish and give you a maximum of 21/2- oldest dog a few new tricks. If you lack 3 years to complete the course -plenty the know -how, be sure the school you of time for anybody who is the least select offers training for the novice. bit serious about his studies. To take the advanced courses -which generally include mathematics as part About the GI bill of the curriculum -the schools require If you are a veteran, the Government you to have had either specific training will pay for certain home study courses, in or its equivalent practical experience. provided you enroll within 3 years after Some home study schools operate like your discharge from military service. engineering colleges -that is, they offer Some two dozen electronics courses a large choice of subjects, permitting offered by 10 correspondence schools are the student to take as many as a half- certified under the "Korean GI bill." The schools with GI- certified courses The contract, whether it's called "En- rollment Blank" or "Application for aren't necessarily better than the Admission," is binding upon you and the others -certification merely means that school, and outlines the rights and obli- the courses meet certain standards and gations of both parties. the schools have agreed to abide by 76 RADIO -ELECTRONICS

www.americanradiohistory.com ELECTRONICS specific Government bookkeeping and service, the qualifications of the instruc- billing procedures. tors, the equipment supplied, tuition If you take your home study training costs, time payment plans, the place- under the GI bill, you still pay your ment or job reference program, etc. tuition directly to the school out of your ( Some school catalogs leave much to own pocket. Every 3 months you re- be desired. Of 13 home -study school ceive a check from the Veterans Admin- catalogs examined in the preparation of istration on the basis of the number of this article, 6 didn't have any specific lessons you have completed, at so much reference to the qualifications of their per lesson. When you have successfully instructors and 2 didn't contain a list or completed your training, you will have summary of lessons and kits included in been repaid approximately the cost of the course.) your tuition. The catalog should tell or show you As a matter of fact, some schools let the answers to these questions about the the veteran defer his payments until "personalized" aspect of the course: the Government check arrives. Your Does the school have complete and thor- local VA office can give you a list of ough exams at the completion of each schools offering electronics home train- phase of training? Are they promptly ing under the GI bill. graded and returned? If you fail to answer a question correctly, do the in- How to get going structors tell what you did wrong or do they just mark it incorrect and let it go Bearing all these things in mind, you at that? Can you get unlimited personal are now ready to choose the particular answers to questions that come up dur- course and school which is best for you. ing the course of your studies or lab Unfortunately, here you may be buy- work? ing a pig in a poke if you don't proceed It's a good idea to ask for a sample carefully. There is no universally ac- lesson -no school that has something to cepted accrediting organization for offer should be reluctant to let you see home study schools as there is in the one of its lessons. Some schools have a field of college education. standard "sample lesson" which may be One organization, the National Home longer or more profusely illustrated Study Council (NH SC), has undertaken than the regular lessons sent to stu- an accreditation program, and its list, dents. which currently includes 10 schools of- To avoid receiving a specially doc- fering electronics courses, is available tored "sample lesson," you can ask for from the council at 1420 New York a specific one by number. For example, Ave., Washington 5, D. C. we asked 24 electronic home study accredited schools While the NHSC- schools to send us Lesson No. 5 in their are required to adhere to certain codes basic TV radio course. Only 4 of them of ethics, educational standards, reason- did, but those lessons we received told able prices and truth in advertising, a us a great deal about the value of the large number of excellent schools of instruction. unimpeachable reputation are not mem- If you receive sample lessons, look bers and have never applied for mem- them over carefully. Do they seem old bership. and outdated? Do they have enough There are two other groups which illustrations to demonstrate the lessons accredit both resident and home study clearly? Is each individual subject fully schools: the Engineers Council for Pro- treated and completely covered? Are fessional Development (ECPD), which the examination questions at the end of approves engineering courses only, and each lesson concise, clear and compre- the National Council of Technical hensive? If you know an electronic Schools (NCTS). technician or engineer, ask him to look After you have decided what type of over the sample lessons and give his course you want to take -basic serv- opinion of the value of the material. icing, communications, engineering, Another way to check on a school is math, color TV, etc.-your best bet is to talk to its former students. Any to write to as many schools as possible reliable school will be happy to furnish and ask for information. the names and addresses of recent Most of the schools advertise in maga- graduates in your area on request. zines dealing with the electronics field. Talk to these men and get their opinions You will have no trouble compiling a of the quality of the instruction, the list from the advertisements, or you way the student is treated, the staff, may want to select from the list printed etc. a Then here as starter. write -and Several of the schools employ "rep - wait for the barrage! resentatives"-a fancy word for sales- Schools answer their mail 'quickly, men -and if you write to a group of usually sending out a catalog and other home study schools, you most certainly is form literature the day the request will be contacted by some of them. received and dispatching a personal an- While they can be helpful in answering swer to your questions later. your questions, they can and do some- Reading the catalog in the light of times make promises which the school the points already mentioned will reveal is not obligated to keep. Put your to you a great deal about the school and its training. It should tell you what the course will cover (usually with a list of Typical home study lessons from four schools. lessons and the subjects they include), Mimeographed or printed, lessons should the extent of personal query -answering be easy to understand and up to date. AUGUST, 1959 77

www.americanradiohistory.com ELECTRONICS

dependence not on word -of -mouth claims Chicago Vocational Training Corp. but only on what is backed up in writ- 3330 University Ave., S. E. ing in the contract and catalog of the Minneapolis, Minn. school. Christy Trades School, Inc. Remember, the school is legally re- 4804 N. Kedzie Ave. quired to live up to the statements in Chicago 25, Ill. its catalog, but not to statements made by its salesmen. Commercial Trades Institute TUBE PROBLEM: 1400 W. Greenleaf Ave. Chicago 26, III. The Armed Forces The contract needed a new version When you finally enroll in a home Coyne Television Home Training Div. of the 6J4 reliable study school, you'll sign a contract 1501 W. Congress Parkway Chicago 7, III. tube type which would (usually called "Enrollment Blank" or provide a tube life "Application for Enrollment ") which Delehanty School of Television of almost 1000 hours. defines your rights and obligations and III E. I I th St. Existing tubes of the school's responsibilities. Read it New York 3, N. Y. this type had an carefully. DeVry Technical Institute average life of only The entire school catalog is actually 4141 Belmont Ave. 250 hours. In addition, "part of the contract," since the con- Chicago 41, III. this new tube had to tract specifically binds the school to be produced under perform the services "as described in E -I Electrical School ultra -high quality 2503 St. Charles Rd. the current catalog" or "as described Bellwood, Ill. control standards. in the school literature" or some similar phrase. If you have any questions Electronic Technical Institute SONOTONE about the contract, write to the school 970 W. Manchester Blvd. SOLVES IT: before signing it -and save the reply Inglewood, Calif. By making you receive, in case you have to refer Electronics Institute improvements in to it later. 4600 Troost St. the cathode alloy and After you begin your training, if Kansas City, Mo. setting up extremely you feel that the school's courses or contract have been misrepresented in Grantham School of Electronics tight controls in 821 19th St., N. its advertisements or literature, W. precision, manufacture send Washington 6, D. C. complete details to the Federal and checking, Trade 1505 N. Western Commission, Washington 25, D. C. This Sonotone engineers probably won't Hollywood, Calif. produced a 6J4WA help you personally, but it may prevent Hollywood Radio & Television Institute with a minimum life of the school from deceiv- ing future enrollees. 7078 Hollywood Blvd. 1000 hours... most Home Hollywood 28, Calif. running much longer. study schools are carefully policed by federal and state govern- Industrial Training Institute RESULTS: ments, and deceptive ads and wild 2150 Lawrence Ave. claims are far less of a menace than Chicago 25, Ill. The Sonotone 6J4WA they were a generation ago. International is one of three reliable As you read this, more than 1,500,000 Correspondence Schools tubes now being people in the United States are getting Scranton 9, Pa. manufactured under training by mail. Many highly success- National Radio Institute U.S. Army Signal ful electronic technicians and engineers 3939 Wisconsin Ave. Corps RIQAP received all or most of their technical Washington 16, D. C. (Reduced Inspection training through home study. Quality Assurance National Schools If you select your school carefully 4000 S. Figueroa St. Program), monitored and discipline yourself diligently in Los Angeles 17, Calif. by the U. S. Army your home studies, you can get a tech- Signal Supply Agency nical education second to none by mail. Pacific International College of Arts & Sciences 5719 Santa Monica Blvd. And the same rigid It's up to you. END quality standards Hollywood 38, Calif. apply to Sonotone's SOME HOME STUDY SCHOOLS Radio -Television Training Association entertainment type OFFERING ELECTRONICS COURSES 52 East 19th St. tubes as well. American School New York 19, N. Y. Drexel Ave. at 58th Street Let Sonotone help Radio -Television Training School Chicago 37, III, solve your tube 5100 S. Vermont Ave. problems, too. American Technical Society Los Angeles 37, Calif. 850 E. 58th St. Chicago 37, Ill. RCA Institutes Ascot School of Electronics' 350 W. 4th St. Box 29092 New York 14, N. Y. Los Angeles 29, Calif. Sprayberry Academy of Radio -Television Canadian Institute of Science & 1512 Jarvis Ave. Technology, Ltd. Chicago 26, Ill. 412 5th St., N. W. Washington I, D. C. United Electronics Laboratories Capitol Radio Engineering Institute 3947 Park Drive C 3224 16th St., N. W. Louisville 16, Ky. o R Washington 10, D. C. Sonotone ® P. Video Specialties Central Technical Institute Elecrronlc Applications Division, Dept. TE -89 4570 E. Firestone Blvd. 1644 Wyandotte St. South Gate, Calif. ELMSFORD, NEW YORK Kansas City 8, Mo. Leading makers of fine ceramic cartridges, speakers, micro- NOTE: This is merely a reference list of some of ph ones, tape heads, electron tubes. Cleveland Institute of Radio Electronics 4900 the many home study schools offering electronics I n Canada, contact Atlas Radio Corp., Ltd., Toronto Euclid Ave. courses. It does not constitute endorsement or Cleveland 3, Ohio recommendation in any way. 78 RADIO -ELECTRONICS

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1 Radio Shack's new 1960 catalog, GUIDE TO ELECTRONIC BUY- RADIO SHACK CORPORATION, Dept. 8E ING creates a new standard in electronic catalogs. It's big .. . 730 Commonwealth Ave., Boston 17, Mass. 81/2" x 11 ", has over 250 pages, lists lowest net prices on Please send me the following: everything electronic, contains up -to- the -minute feature articles engineering charts and data prepared by leading authorities, yuan. REALISTIC Sh. Wt. Order Nn. Sale is profusely illustrated with big clear pictures and is hand- Magnetic Earphone '/ lb. 91L17`_ $ .98 somely printed in rotogravure. Ready in September. Crystal Lapel Mike y-_ lb. 91L100 2.85 8 Transistor Radio 2 lbs. 90LX698 29.95 Extra Radio Bat. 1/2 Ib. 95L020 0.59 FREE Radio Shack Bargain Bulletins FREE Radio Shack RECORD Bargain Bulletins Articles! Radio Shack 1960 ELECTRONIC BUYING GUIDE -35c Big Pages! RPORI T /ON - Name ashington St., Boston 8, Mass. Big Pictures! Address 30 Commonwealth Ave., Boston 17, Mass. Data! 230-240 Crown St., New Haven 10, Conn. City Zone Slate Tables!

AUGUST, 1959 79

www.americanradiohistory.com ELECTRONICS

Nonamplifier oscillators use diode The connected tubes or transistors, or crystal diodes 1 DES CAN OSCILLATE

By I. QUEEN EDITORIAL ASSOCIATE

MOST oscillators are the feed- 1 me can be obtained with a suitable a transistor can also be connected as a back type. Actually, these are tank. diode oscillator. The circuit seems to amplifiers which feed back a Reverse -biased diode oscillators were combine certain features of the reverse - portion of their output to re- known more than 30 years ago. Fig. 4 biased diode and of the ionic inforce oscillator. their input (see Fig. 1). This is a diagram from an article in THE It is shown in Fig. 6. The p -n -p tran- lowers the effective resistance. When EXPERIMENTER of March, 1925 (page sistor is diode -connected and the base circuit resistance drops to less than 299), describing the experiments of the is left free. R1 is a limiting resistor zero, even the slightest voltage dis- Russian scientist Lossev. The diode is to protect the circuit and transistor. turbance will build up. Eventually the a zincite crystal, and about 12 volts R2 controls the bias current. Both circuit oscillates at full intensity. Since reverse bias is required. The oscillation resistors are suitably bypassed. Some- amplification is involved, we expect frequency is determined by Cl, L2. times, R3 (unbypassed) will also be these circuits to include one or more The other network (C2, L3) prevents needed for waveform control. triode or multi -element devices. rf from entering the battery. Transistor types 2N112, 2N112A and Certain nonamplifying devices -in- A different kind of diode oscillator* CK768 were found suitable as diode cluding diodes and thermistors -can is described by Thomas E. Fairbairn oscillators. No doubt others may also also be adjusted for negative resistance. in RADIO -ELECTRONICS in December, give satisfactory results. Low -fre- Therefore they can oscillate. One type 1953 (page 76). Known as the "ionic quency types such as the CK722 and of diode oscillator was described by oscillator," it consists of a gas tube 2N107 did not work, at least not at the Rufus P. Turner in RADIO- ELECTRONICS and voltage source. (See Fig. 5.) Elec- low voltages I used. Optimum voltage in October, 1949 (page 47). Fig. 2 trons flowing through the tube ionize seemed to be about 22.5 or slightly shows his circuit. A 1N34 is reverse - the molecules of gas and set them higher. Some transistors oscillate well biased (with between 50 -175 volts) to vibrating. The oscillating frequency with a 22.5 -volt battery. For conven- its negative resistance region (Fig. 3). depends only upon the tube type and ience I used a 45 -volt battery for tran- Here an increase in voltage causes a not upon any external tank. If plate sistors which refused to oscillate with decrease in current. With the audio current is held to a minimum, the wave 22.5 volts. Of course, the higher voltage transformer shown in the diagram, the is a pure sinusoid and stable. Note requires a high series resistance (R2). output is in the audio range. Up to that the tube is diode -connected. The Nearly every transistor tested (of grid may be used the types mentioned previously) FEEDBACK as modulate and was -E- control the oscillations, but is not found to oscillate. Optimum reverse needed to generate them. current is approximately 0.4 to 0.5 ma in nearly every case, although one unit Use a transistor required as high as 0.8 ma. In general, From recent experiments I find that the output waveform is sinusoidal when Fig. 1 -Block di: grani of feedback type the current is kept low. The sine ampli- oscillator. *Patent No. 2,607,397 tude varies between 0.1 and 0.5 volt. CH RI The 2N112 generates a sine wave of 130V /1OOMA SEL RECT VOLTAGE CONT 300V about 8 or 9 kc. The CK768 frequency + 10H/55 MA 50K is approximately 3 times greater, near

RECT I .I /400V 24 kc. T SEC CI + + COPRI 1I7 VAC - II SINE WAVE OUTPUT C3 20/g50V R2 D 3 I AUDIO TRANS + 2

RI -pot, 50,000 ohms, wirewound RECT I, 2- selenium, 130 volts, 100 ma R2- 10,000 ohms, 10 watts, wi ewound S -spst toggle CI, 2, 3 -20 µf, 450 volts, electrolytics T-audio transformer, 3:1 ratio C4-0.1 µf, 400 volts Chassis, to suit CH -ac-dc choke, 10 h, 55 ma Miscellaneous hardware D -1 N34 Fig. 2 -Diode oscillator uses 1iN3l crystal. Trans- Fig. 3- Crystal voltage- current curve former secondary is higher -impedance winding. shows negative -resistance point. 80 RADIO -ELECTRONICS

www.americanradiohistory.com ELECTRONICS will rise, also, as Handle any L3 voltmeter. The voltage the current grows and will reach a peak. After that, the voltage will begin to drop even though the current con- Radio-TV tinues to rise. This indicates the nega- ZINCITE CRYSTAL tive resistance region. If the peak occurs below 19 or 20 volts, it indicates Job that the transistor will oscillate when Service used with a 22.5 -volt battery. If the EASIER - BETTER FASTER! peak appears at a higher value, you can use a 45 -volt battery with suitable Fig. 4-This diode oscillator circuit ap- series resistance (R2). + geared in 1925. The reader may point out that the 2N112 and CK768 both specify 15 volts 884 OR OTHER GAS TUBE maximuum between emitter and collector. More than half of the transistors tested here reach their peak voltage at less than 17 volts so there is little if n -22V any overload when the transistor is negative resistance region. Fig. 5-Gas-diode oscillator. Grid can be used in the used to modulate oscillations, but is not 2N112 needed to generate them. CK768 BATT v II+ As bias current is increased, the CI .02 RI 5.66 SEE TENT Only 13 Beyond a for the complete waveform becomes distorted. R3 500n 2-volume course certain critical point the transistor BASE CONN NOT USED 3 MONTHS TO PAY breaks into sawtooth generation, with a large increase in amplitude. Unlike R2 the "ionic" or sine condition, it is pos- COMPLETE SERVICE TRAINING frequency C2 .05 written so you can undersi'and it! sible to vary the sawtooth RI -5,600 ohms, I// watt ... over a wide band. With one particular R2 -pot, 50,000 ohms No complicated theory or mathematics ! These right down .o brass unit, the sawtooth frequency R3 -pot, 500 ohms famous Ghirardi books get 2N112 BATT -see text tacks in showing you how -to handle ail types of was 12 kc with 1 -ma bias current. At CI -.02 tif, 200 volts AM, FM, and TV service work by approved and the frequency dropped to 6 kc. C2 -.05 µf, 200 volts professional methods. Almost 1500 pares 0.5 ma, V- 2N112, CK768 over 800 clear illustrations show how handle With a 0.5 -µf capacitor shunted across Chassis, to suit every phase of troubleshooting and se rvicing. Miscellaneous hardware Each book is co- authored by A. A. Ghirardi whose the transistor, frequency was reduced helped train more servicera,en than ampli- Fig. 6 -The p -n -p transistor in a diode manuals have to only 300 cycles. The sawtooth oscillator circuit. other books or courses of their kind! tude remained nearly constant through- 1 -Radio and Television Receiver out this wide band. Any intermediate VOLTMETER TROUBLESHOOTING AND REPAIR frequency may be obtained by a suitable BATT This big book is a complete guide to -profitable value of bias current or capacitor professional methods. For the beginner it is a shunt. 02 5.66 SEE TEXT comprehensive training course. For the experienced serviceman, it is a quick way to "b -ush up" Of a very large number of tran- on specific jobs, to develop improved techniques sistors tested here, two gave an un- or to find fast answers to puzzling very ce problems. Includes invaluable "step -by -step- service usual result. As the bias was increased charts. 820 pages, 417 illustrations, price $7.50 from some low value, a pure sine wave R2 separately. died down was observed but it quickly C2 A5 2 -Radio and Television Receiver increase brought the to zero. Another CIRCUITRY AND OPERATION wave back but again it died out. Each Fig. 7- Testing transistors for use as oscillators. This 600 -page volume is the ideal guide fen -.rvicemen time, the control could be backed off and diode who realize that it pays to know what really ma' modern will require radio -TV receivers "tick" and why. (rives complete advanced with momentary appearance However, other transistors understanding of basic circuits and circus -- ai iations; 20 volts or more to reach how to recognize then) at a glance: how Ir ol iminate of the sine wave. With these two tran- approximately guea,worli and useless testing in servicing h. :Ii. Spewis voltage permitted negative resistance. While this appears up your work -takes the "headaches" out of lough jobs! sistors, reversing the 417 ills +. !'rice separately $0.75. normal oscillation. In other words, the to be rather high, it has been applied positive terminal was connected to the for many hours to several such tran- Special low price...you save $1.25 sistors with no apparent damage to It broken into lesson, and sent to cam u . a "course," collector. you'd regard these two great book, n: ,1. tMcain at $75 or more! If your transistor shows a sawtooth them. book. sine Under this new offer: you save $1.23 on the two - or distorted output even with R2 set to When the circuit is adjusted for and have the privilege of paying in ra y iII'io llment' ichilc is you use then!! No lessons to wait for. Ti=c. ' art fond -- maximum resistance, add R3, an unby- generation and low output, it highly and right! show this, passed resistor. This has little effect sensitive to temperature. To r _ _ STUDY 10 DAYS FREE! I. on bias current so you retain sufficient set R2 so that sine output is 0.1 volt if you the transistor Dept. RE -89, RINEHART & CO., Inc. input (and therefore output). How- or less. Now touch 232 Madison Ave., New York 16, N. tX a value for R3 elim- for a second or two, the frequency will Semi books below for l0 -day FREE EXAM( OOTittN'_ ever, even small In 10 days I will either remit price Incite ',-t llo, to rise and the amplitude will postage) or return books postpaid .tnd ow u,p inates distortion from the wave and start nothing. leaves a pure sine wave. This is similar fall. In most cases the sine wave will eceiver TROUBLESHOOTIN7r..+. REPAIR 1 will (Price &$7.50 separately) a few seconds. It i 1 to the ionic oscillator, where for best disappear within Radio & TV CIRCUITRY & OPERATION .e $11.75) transistor has cooled Check here for MONEY -SAVING COMEINATION return when the f _tbove big waveform Fair'bairn recommends a OFFER . Save $4.25. Send both if you haven't changed R2's setting. books at special price of only $13.01 tvo. higher voltage and higher series resist- (Regular you S 1 at rate f$4 plus postage af O 1cs t pécedid you will p,us for 3 months By calibrating the control books anti $3 month U't ance. to keep the 4TRhi One total of R43.04) k5, 0Ca tp'"1 T' Rl t j have some sort of temperature indica- with order 2/td pay postage.ó"i1F -dry return r f-undod. Tests with transistors tor. If the potentiometer is set high privilege) with money My tests show that only about one enough, so that the wave doesn't go to Name 1 out of eight transistors refuse to oscil- zero, you will note that the frequency IAddress late in the Fig. 6 circuit. To test a rises considerably with temperature. 1 City, Zone, State transistor for suitability, connect it as Touching the transistor for about 2 1 Outside U.S.A. -$8.00 for TROUBLESHOOT- 1 seconds may cause its frequency to ING REPAIR; $7.25 for CIRCUITI } OI'ER- shown in Fig. 7. Start with R2 set for 1 .ITION; $14.00 for both. Cash only, but 1 maximum resistance. Now slowly re- rise from 8 to 9 ke in a very short money refunded if you return books in 10 days. duce the resistance while observing the time. END L-- s...1=miumm - -- AUGUST, 1959 81

www.americanradiohistory.com Plain Facts about ELECTRONICS and CREI why you need advanced electronics education -how you can get it without quitting your present job

NO DOUBT you know what is hap- tronics guides them and makes them education in nuclear engineering 'felling in electronics. You know tech- intelligible. nology. Last year also marked that the electronics industry is grow- the And you know that the day of the opening of our European Division, ing with extraordinary rapidity. You mediocre electronics man is done. bringing advanced professional know that regardless of the ups and elec- Added responsibilities and salary in- tronic education to downs of the business cycle, Western Europe. openings creases go to men with both the- are always found Since 1927 we have directed the for oretical and practical men with technical education of thousands solid, advanced knowledge. -as electronics education. individuals and in groups -in elec- You know that every CREI home study tronics engineering technology. We computer needs installa- courses make you eligible developed the first civilian pilot course tion and maintenance. for positions which re- for radio mechanics for the Army quire advanced electron- You know that every Signal Corps in 1941, supplied 300,000 ics education. You need texts to the U. S. Navy in missile carries the end not quit your present a special course for radio result of years of elec- job. You can meet your technicians in the tronics planning and de- family responsibilities South Pacific in 1943, trained hun- velopment. You know while gaining knowledge dreds of technicians during World that every piece of radar of electronics engineer- War II for the Signal Corps. We co- equipment, every servo- ing technology so essen- founded the National Council of Tech- mechanism, every astro- tial for career advance- nical Schools, which first established nautical device, requires ment. scholastic and business standards for not only electronics de- the technical school field. We were CREI'S signers and builders but among the first three technical QUALIFICATIONS insti- also electronics mainte- tutes whose curricula were accredited nance personnel We are now in our as well. by the Engineers' Council for Pro- You know that our new 33rd year. Last year fessional Development. In 1946 we awareness of outer space is founded marked the start of CREI Atomics, instituted the group training pro- on the inner workings of satellites. a division of CREI devised to meet grams now used by companies which Rockets make them possible and elec- the need for advanced home study represent the cream of the electronics [ADVERTISEMENT] 82 RADIO -ELECTRONICS

www.americanradiohistory.com and aviation industries. In 1957 we time we have corrected and com- QUALIFICATIONS FOR CREI initiated a plan which permits direct mented on many hundreds of thou- College degree is not essential. personal supervision for home study sands of examinations, enables us to If you have had basic electronic educa- final exams. anticipate questions in our lesson tion, practical experience in electron- What does this record of achieve- material and minimize troublesome ics, and a high school education, you ment mean to you as a CREI student? points. can probably qualify. A good way It means that industry and the Armed to find out: Use the postage -paid card. Services alike respect CREI men. CREI STUDENTS It It will bring you the free book which means that your CREI diploma is a Our active home study roster today has launched thousands on their ad- door opener. numbers more than 17,000 professional vanced careers: "Insurance For Your Significantly, Help Wanted ads of- electronics engineers and technicians, Future in the New iNSIWANCE World of Electron- ten specify "CREI education or equiv- all over the world and in every phase PON W,W .11 UWE v n.e. NEW +n'ORLO av ics." Please fill out alent required." Our Placement Bu- of electronics, about one -third mili- elr.eTlgrrCa the card carefully, reau, which helps graduates and ad- tary, the rest civilian. Their median vanced students find more desirable checking appropri- age is 28. Last year they devoted ate items and pro- positions, is always available to CREI approximately 1,572,465 hours to viding essential men. While no placement guarantees 104,831 lesson texts, answered (and data. Tuition is will be made by CREI or any other were individually graded upon) 1,048,- reasonable and may reputable institution, for many years 310 searching questions and engineer- be paid monthly. It takes just one the demand for CREI graduates and ing problems. They studied electronics $10 -a -week raise to repay your advanced students has far exceeded investment in CREI education and the supply. engineering technology - transistors, microwaves, forward scatter, comput- leave you a substantial bonus the Paul S. Lewis, Jr., a research assist- ers, servomechanisms, radar, elec- first year. Available to veterans under ant in an AEC -sponsored nuclear phys- tronic navigational devices, and the GI bill. ics research program -and a CREI entire field of modern electronics. student - writes, "Like most large - New students enrolled during the year LATEST CREI COURSE scale physics projects, this are on the missile ranges Automation and Industrial machine (a proton accel- of Vandenburg AF Base Elec- tronics Engineering erator) is largely elec- and Cape Canaveral. They Technology. Com- tronics. The need for are at Alamagordo and plete course, covering all electronic electronics technicians on China Lake, at SAC bases phases of automation. Special empha- basic scientific research around the world. They sis on theory, functioning and appli- projects will no doubt con- are in the research labo- cations tinue to grow." of servomechanisms and com- ratories and manufactur- puters. Also noteworthy-lessots on Charles E. Lawson, an- ing plants where the la- machine control, instrumentation, other CREI student, brings out an- test electronic equipment is designed data processing other point: "The fact that I am and produced. They maintain elec- and telemetry. enrolled with CREI was met with tronic equipment for United Air Lines enthusiasm on the part of my em- and Trans -Canada Air Lines. They ployer, Wright Airborne Electronics. share in electronics at All- America A former student of CREI is now chief engineer for the company." Cables and Radio, Inc., and The Martin Co. They work for U.S.I.A. (Voice of America) and Columbia CREI HOME STUDY ADVANTAGES Broadcasting System, for Gates Radio RESIDENCE SCHOOL Technical education is accomplished and Federal Electric, to name but a on your own time, during hours chosen few. All of the firms mentioned offer For those who can attend classes, by you. You waste no time in travel. their personnel CREI technical edu- CREI operates residence programs in You have plenty of time to do your cation under company plans. CREI Washington, D. C. Day and evening best. Your work is under men are found by the classes start at regular intervals. the supervision of a regu- hundreds among field Qualified graduates earn AAS degree. lar staff instructor who engineers of major elec- Electronics experience not required guides your progress step manufacturers. tronic for admission. by step. Courses are pre- They're across the world pared by experts, present- -and across the street. CAPITOL RADIO ed in easy -to- understand They are the men you ENGINEERING INSTITUTE form, kept up to date by must compete with to Founded 1927 FCPD Accredited Technical Institute Curricula periodic revision. Experi- hold your place in the Dept. 148F1 ence in more than three decades electronics profession. Wouldn't you 3224 16th St., N.W. of home -study teaching, during which like to be as well qualified? Washington 10, D. C. Z` [ADVERTISEMENT] AUGUST, 1959 85

www.americanradiohistory.com TEST INSTRUMENTS These few simple gadgets that you can OSCILLOSCOPE easily put together will make life with your scope a lot easier, and perhaps COMFORTS help make your viewing more accurate By T. J. BOIPKINS PLEXIGLAS CATHODE - SHADE BEZEL RAY TUBE

INSIDE EDGE HAS 5 -1/2° RADIUS 2 HOLES FOR 2/56 SCREWS

RADIUS 1/4° 'SOLDER

ENVIOUS of the man whose scope has a lighted graticule? You don't have to be. Here is a simple way of adding an illuminated graticule to your scope. Cut a disc of clear Plexiglas to fit your scope's bezel ring (use 1/4- or 3/8-inch clear Plexiglas). Then flame - polish the edge and paint it black, except for a 1/2-inch section at what will be the bottom. On this disc you can scribe any desired scales or pattern with a sharp pointed tool. Be careful; once you scratch the surface, it is very difficult to remove the mark. At the bottom of the metal bezel ring, drill a 1/4 -inch hole. Just below this on the panel, drill a 1/2- inch hole as close to the bezel ring as possible. Next, make the tin housing. The top can be trimmed after the end is attached, but the bottom flange must be shaped beforehand. Flow solder thickly around the edges and, when cool, trim with a small file and paint the- outside the same as the scope case. The housing is installed with two 2/56 screws and nuts. The pilot lamp fits through the hole and into the housing. To show the graticule lines in color, insert a sheet of colored cellophane ( preferably blue or green ) between the CRT face and the Plexiglas disc.

86 RADIO -ELECTRONICS

www.americanradiohistory.com TEST INSTRUMENTS

4 N °6 SHEET METAL SCREWS 5/8" N 5/8" 5/8" STOP BAR 5/8° ar, . 1/2" N °24 1/2" ALUMINUM BENT TO FIT ANGLE

10 1/4° - 1 3/4 "X I /8" ALUMINUM k 9-1/4" STRIP

15-1/4"

I"X I" X I/16" ALUMINUM - NFF1 ANGLE 10/32 I ly 10/ ß- \ \II -T NOTES: L \=J All aluminum strips are 24 gauge. 1/2" All screws shown without nuts are No. 6 sheet -metal screws. All machine screws are I/2 inch long.

FOR CORNERS T FOR NOTCHES SEE Do not overtighten sheet -metal screws or CUT 90° WEDGE 6" DETAIL DRAWING they will strip the soft aluminum. AND BEND ABOVE 3/4" X I/8 "- - STRIP I

TIRED of craning your neck to see the scope face when the scope is on the bench? Try this adjustable rack. It is made from strips of 1 -inch aluminum angle and 3/4 x 1/8 -inch aluminum strip. You can use sheet - metal screws or flush rivets to hold the works together. To adjust the rack, set it up on the highest position with the legs straight down, and slide the stop bar to the desired position. Then lower the whole thing until the stop bar slips into a notch. Of course, you REFLECTIONS on the screen are can body with a pair of tin snips. can cut as many notches as neces- a nuisance and, unless you like to Paint the outside to match the sary. work in the dark, a shade over the scope and the inside a It black. scope face is a must. Here are two Presto! You have a scope shade that ANOTHER handy little gizmo is a miniature alligator clip that has

BRASS TUBING

been soldered to a short length of 5/64 -inch inside- diameter brass tubing. Pinch the tubing a little, and a test -prod tip will fit tightly. Then shades which you can make in min- snaps on. For a 3 -inch score I used you can clip it to any part of a cir- utes. For a 5 -inch scope take an a peanut can. It very nearly fitted cuit you want and have both hands empty coffee can, remove its bottom the bezel, so I squeezed it slightly free for any work or scope adjust- with a can opener ( the kind that out of shape and it stays im beauti- ments that may be necessary. leaves a smooth edge ) and slit the fully. END AUGUST, 1959 87

www.americanradiohistory.com TEST INSTRUMENTS

MEASURE CAPACITANCE with a r VTVM

By JOHN L. JANNING, W8QCN

TECHNICIANS and experimenters the vtvm, the reading would be off average reading of several capacitors can make good use of a capacitance scale. of the same value. meter. The technician looks at such To handle this problem, resistor R1 When using the instrument, readings a unit as an appealing investment is inserted as in Fig. 2. Now it is pos- that show lower capacitance than while to the experimenter it is a valu- sible to adjust the reading to bring marked on the capacitor indicate able luxury. But by making a simple high -value capacitors within the vtvm's changed value or a slightly leaky condi- inexpensive accessory for your vtvm, 5 -volt range. Next, we add capacitor C tion. A high reading usually indicates you can add a capacitance scale that so the capacitance scale can be zeroed a very leaky capacitor. Use the ohms will measure from 250 µµf to 0.5 µf. easily. scale to make certain. Fig. 1 is the basic circuit. A filament To use this circuit, set the vtvm to If you don't want a separate acces- transformer delivers 6.3 volts, which is its 5 -volt do range and connect the sory cluttering up the bench, build the then rectified. This gives us pulsating capacitance meter to the vtvm's dc unit right into your vtvm. If you do do which cannot be measured on the do input through the do probe. Then, zero so, you can use the filament winding of volts range of a vtvm. (This is not the left side of the scale with the vtvm's the vtvm's power transformer to supply true of a vom.) If a capacitor is placed zero- adjust control. The right side of the necessary 6.3 volts. The circuit is across the vtvm's input (shown in the scale is zeroed by shorting the un- shown in Fig. 3. In this circuit, a high - dashed lines), only the filtered portion known- capacitor probes and adjusting value resistor equal to the one in the is read. The larger the capacitor, the R1 for full -scale deflection. meter's dc probe is used as R2. The higher the do reading. If a large capaci- When calibrating the capacitance switch and the high -end zero control tor-0.2 or 0.5 µf -were placed across scale for the vtvm, make sure that the can be mounted on the back of the vtvm. vtvm has been turned on for at least 15 The lead connected to the vtvm's do minutes. Check the scale zeros next. volts jack is removed and connected to VTVM Then connect good -tolerance known - point X in Fig. 3 and the aim of S1 -b is 117 VAC 6.3 V 5V DC SCALE THROUGH DC PROBE value capacitors to the unit and mark connected to the jack in its place. the meter reading with the value of the When capacitance is read with this Fig. 1 Basic capacitance- measuring capacitor. The front -panel photo shows unit built -in, a straight probe is used. - circuit. how this may be done. The unit will The vtvm's do probe will give a false be only as accurate as the capacitors or no reading. If the Fig. 2 circuit is RECT + R used to calibrate it. So if close- tolerance used (external accessory), the standard 25 V/65 MA 75K capacitors are not available, use the do probe is used. END 117VAC 6.3V VTVM (SEE PARTS RECT s 600 MA 5V DC SCALE (SEE PARTS LIST THROUGH DC PROBE LIST)T RI 25V/65MA 75K R2 CAP SI -a TO LEAD REMOVED 117 VAC II 6.3V I ZERO o SELECT R FROM DC VOLTS JACK 600 MA t;0 1 ROL UNKNOWN DC CAPACITANCE o,4,gl -b DC VOLTS .5 o R -pot, 75,000 ohms C -0.5 µf * UNKNOWN CAPACITOR RECT -selenium, 25 volts, 65 ma (International SI -c 0 GROUND Rectifier QIH or equivalent) o T- Filament transformer: primary 117 volts; secondary 6.3 volts, 600 ma (Triad F -I 3X RI -pot, 75,000 ohms Rectifier Q I H or equivalent) or equivalent) R2- resistance equal to resistor in vtvm's dc probe SI -3 -pole 2- position slide Chassis box to suit C-o.5 µf T -use filament winding of transformer in vtvm Miscellaneous hardware RECT -selenium, 25 volts, 65 ma (International Miscellaneous hardware Fig. 2- Simple circuit for an accessory Fig. 3 -When the unit is built into the vtvm, use the existing type capacitance meter. transformer for the capacitance meter's 6.3 -volt ac supply. RR RADIO -ELECTRONICS

www.americanradiohistory.com TEST INSTRUMENTS More sockets and fewer controls on the face

sa $@ ,9 of your tube tester can convert lost time into d fi, found money y:; . MANY S ,,.;'_,

SPEED TUBE

CHECKING By WILLIAM KELVIN*

TUBE testing should be a fast, Mini -Check MC-1 tube test- simple process. The multiple- socket er has selector, load and (or prewired- socket) tube tester function controls. is a big help in making it such. MINI -CHECK TUBE TESTER This instrument lets the service technician give good service without losing money, as he would if he spent a half - hour on each service call just testing Fast Check F(: -2 tube test- tubes. The easy way out of this spot is er has only two controls - to dispense with the tube tester and rely selector and load. on tube substitution. But such a method passes up many legitimate tube sales. This article describes two types of circuitry used by Century Electronics in multiple- socket tube testers. Before we go into these circuits, let's review basic tube -testing principles. All emission testers, whether dynamic (ac test signal) or static (dc test signal) , use a circuit similar to the one in Fig. 1. An ac signal is applied between grid and cathode of a diode - connected tube, while the heater is powered by a separate ac source. The tube, acting as a rectifier, conducts on positive half -cycles. Pulsating do flows through the external circuit and gives a meter indication. Resistor R limits maximum current to a safe value. If cathode emission is substandard, the meter reads lower than for a normal tube. Thus, the lower part of the meter scale can be a red area labeled BAD, the upper part can be a green area labeled GOOD, and our basic tube tester is born. This article is limited to this type of emission tester, since it is in the heater, are connected to the other the overwhelming majority. side of the same winding. If there is a *Chief engineer, Century Electronics Co. Inc., All tube testers must check for inter - short between the cathode and any Mineola, N. Y. element shorts as well as quality. In other element, current flows, a voltage Fig. 2 the cathode of a tube is connected drop appears across the neon brlb, and to one side of the transformer's second- the short indicator lights. The capacitor ary, and all other elements, including and resistor control the sensitivity of the leakage indicator, and keep normal tube emission from appearing as a 117 V AC short. s -` 6.3VTOHTR As an introduction to multiple- socket instruments, let's first take a look at Fig. 1 -Basic tithe testing circuit shows 117 VAC cathode emission ch 'ek. the Freepoint -Lever tube tester. In Fig. 3, a multi -element tube is connected to measure cathode emission NEON through its pentode section. The 117V switches may be lever- action or, in - ol lower -priced instruments, slide switches. Note that each switch lever connects to 117 AC 470K r an element of the tube. When the lever -6.3V is thrown to the left, it connects its Fig. 2- Basic method of testing for Fig. 3- Simplified emission -test circuit respective tube element to one side of shorts. using Freepoint -Lever switches. (Continued on page 92)

AUGUST, 1 9 5 9 89

www.americanradiohistory.com Estimate the value of everytffin:, 41. in this picture ...AND WIN in Westinghouse Giant Jackpot

, ..:"::,.::,..;;ó:á::::i.... c ontest Giant

90 RADIO- ELECTRONICS

www.americanradiohistory.com T ALL! You can win absolutely everything shown in this picture, simply by estimating its total retail value. Would you say hundreds of dollars? Thousands of dollars? The closest guess will win it all! Enter now! Enter as often as you like!

Never before a contest so easy to enter ... so easy That's all there is to it ... and just look what you to win! Four separate contests! Four separate can win! 4 first prizes: "Winner Take All" - Giant Jackpots! And you can enter all four -try everything shown in a Giant Jackpot picture. for the Giant Jackpot as often as you like! Hun- 4 second prizes: Your choice of Westinghouse Re- dreds of other valuable prizes if you miss the top frigerator, Freezer, Laundromat, Dryer, Two Dif- award! ferent Ranges, Room Air Conditioner. Just 3 easy steps to enter... 4 third prizes: Your choice of Westinghouse Re- 1. Ask your Westinghouse distributor for a sup- frigerator, Freezer, Dryer, Range, Air Conditioner. ply of official entry forms ... several for each you want to 48 fourth prizes: Your choice of two Westinghouse contest enter. Immerse-A-Matic appliances and a control unit. 2. Estimate the total dollars -and -cents retail 100 fifth prizes: value (exclusive of local sales and Federal Your choice of Westinghouse excise taxes) of all the items shown and de- Spoutless Coffee Maker or Portable Mixer. scribed in the picture for the contest you are 240 runner -up prizes: Westinghouse Dog -O -Matic entering. You'll receive an information leaflet Hot Dog Cooker. with your entry blanks which shows photo- FIRST graphs of all four Giant Jackpots. CONTEST STARTS AUGUST 3. 3. Write your estimate on the Entry Form and 1959! GF'l' ENTRY mail along with the end panel from a West- BLANKS AND OF- inghouse 5 -pak tray which reads "Westing- FICIAL RULES house Electronic Tubes" or a reasonable FROM YOUR WEST- facsimile to : "Jackpot," Westinghouse Elec- INGHOUSE DIS- tric Corp., Box 365, New York 46, N.Y. TRIBUTOR TODAY. If your distributor does not sell Westinghouse tubes, send his name and address to Westinghouse. Box 284. Elmira. N. Y. YOU CAN BE SURE..IF IT'S W stinjhouse Electronic Tube Division Elmira. N.Y.

AUGUST, 19 5 91

www.americanradiohistory.com leading audio magazines say ... TEST INSTRUMENTS bination of groups of tubes with similar base diagrams. Now what about the other switches? FINEST QUALITY Every time you eliminate a switch you VAC C must either increase the number of c sockets or sacrifice some accuracy of the 6.3V HTR test. If the filament- voltage selector switch is eliminated, there must be a Fig. 4-Sin pli tied quality test of a dual AMPLIFIER CAN BE triode with both triode sections con- complete set of sockets for each popular nected in series. filament voltage. For example, the 6L6, 12L6, 25L6, 35L6 and 50L6 are all of (Continued from page 89) the same type, but each needs a different ASSEMBLED BY YQU the transformer secondary. When the heater voltage. On a panel with no switch lever is thrown to the right, it filament switch, there would have to be connects its element of the tube to the five sockets just for this group. One other side of the transformer secondary. manufacturer of a tube tester with no Most lever- action tube testers have filament selector switch has 123 sockets IN A FEW HOURS! 10 levers, one for each base pin. There on the instrument panel. are a maximum of 9 base pins on any The objection to limitless numbers of Acrosound Ultra -Linear II Amplifier Kits have one tube, plus a top cap. By manipu- sockets is that size and cost become too astounded leading electronic exponents with lating the levers, any tube element can large. their ease of construction and high quality per- be connected into either the plate or You will note that for many tubes the formance. Quick and simple to assemble ... no cathode circuit. Most tube testers of load control setting (it varies the series experience necessary. Lowers cost because you this type have two more positions which resistance, R, of is same, do it yourself! Follow the choice of experts Fig. la) the - are not shown in Fig. 3. These enjoy the ultimate in stereo sound, in your are for and this grouping is enlarged if you home now in a matter of hours! applying heater voltage to the proper include tubes which have almost the pins, and for open- circuiting any de- same load setting. This suggests re- sired base pin. placing the load control with a fixed In addition to 10 lever switches, these resistor equal to the most commonly testers have a filament voltage switch, a plate voltage control and a load control. The more expensive testers have still more controls such as bias, etc. The additional controls make the instrument more versatile, but they also ACROSOUND ULTRA -LINEAR II $7950 slow down testing. AMPLIFIER KIT I 117 V AC Multiple -socket tube testers rated continuous output of 60 watts These units can a With an of less than 1 per have lot of sockets power at an IM distortion uality and a minimum of controls or fewer cent, on Thesentirenconstructionfopegrat the most sockets and more controls. Two units than two hours by Fig. 5 -Basic short and gas tests in a not require more which show this rather clearly are the inexperienced." dual- triode tube. December 1958 -AUDIO Fast Check and Mini -Check tube testers. The Fast Check has 41 sockets and 2 used load value. Although this has been controls. By adding a cathode switching done in some instruments, it reduces As a result of careful predesign circuit, you the U -LII planning, get the Mini -Check which the tester's accuracy. Such a drawback goes together in something two hours. It represents under has 3 controls (the 2 on the Fast Check can be partly overcome by two constructional a superb blend of using ease and superior guaranteed performance, and an added cathode switch) and or more values of fixed load resistance, to delight the most fanatic and hard -to- please only 17 sockets. the most dedicated music but again this entails increasing the listener." There are two keys to the success of HIGH number of sockets to accommodate tube FIDELITY MAGAZINE multiple- socket testers: groups with the same base -pin arrange- December 1958 Many tubes use the same switch ment but which take different load - settings. This is easily checked by control settings. In general, the load a common simple since a examining tube like the 6K6 control should be retained in multiple - "The construction is extremely of basically the entire circuit and noting that its base -pin arrange- socket testers. printed board con- All that is really left to the ment is one is is furnished. the transform- that used by a large The plate switch, however, is one that structor is the wiring of both mounted n the front number of other tubes. This is true of is readily eliminated since the majority ers and the controls that A new 60 -watt amplifierkit many base panel. circuit with ex- -pin arrangements, and of tubes are checked at the same plate employs an unusual feedback stability ... The total time required means that the service technician re- voltage. Only a few extra sockets are ceptional 21/2 hours." to build the kit is approximately peatedly sets up the same switch posi- needed to overcome the inflexibility RADIO & TV NEWS tions in the course of his tube testing. caused by this step, and most multiple - October 1958 So, why not employ some sort of fixed socket tube testers have no plate switch. setup? Since these lever switches do More than 95% of interelement "The steps are few and the booklet companying pictorial and ac- nothing but "wire up" a socket in a shorts involve the cathode. This permits y are clear and easy to follow . , . Test particular results . manner, the answer is to use a great reduction in the required num- most important . In the last and test, the amplifier sounded a prewired socket for this tube. will of sockets since the clean and performed beautifully It ber very rare types levels," at all volume serve, not only for the list of tubes that of interelement shorts introduce only POPULAR ELECTRONICS have the same base -pin arrangement, a small chance for error in tube testing March 1959 but also for other tubes with slightly if they are omitted. These rare shorts 111111111111111111111 different ones. include screen -to- suppressor, plate -to- Write today for FREE descriptive litera- If you classify tubes into groups with plate (in dual- section tubes), etc. ture on all Acrosound Amplifier Kits. the same pin arrangement, you wind up With the various switching economies with a panel of prewired sockets, and described, major manufacturers of mul- ACRO PRODUCTS COMPANY no lever switches! Obviously, if every tiple- socket tube testers have produced 369 Shurs Lane, Phila. 28, Pa. base -pin arrangement were used, too instruments whose panels have from 12 many sockets would be needed. The to 123 sockets, and with between 1 and ACRO THE FIRST NAME IN AUDIO ... number can be reduced by careful corn- 5 control knobs. 92 RADIO- ELECTRONICS

www.americanradiohistory.com TEST INSTRUMENTS THERE'S GOLD IN THIS C -D 117 V AC TREASURE CHEST

.01

SHOR W QUALITY Fig. 6-How a dual triode is switched from a parallel to a series connection. Here is a challenge to the service industry -an economy in time at a slight cost in accuracy! Is it acceptable? Service technicians have replied with a powerful affirmative which has been proved by the thousands of instruments sold.

2 controls and 41 sockets The Fast -Check circuit uses a filament- voltage selector and a load control. It has 41 sockets and tests over 700 tube types. It features a special manner of testing dual- purpose tubes so that tube sections are in parallel for the short test, and in series for the quality test. Fig. 4 shows how dual -purpose tubes are checked in a single step. If both triode sections have normal emission, the meter will indicate a GOOD tube. But if one section has low emission, the meter will indicate a BAD tube, even though the first section is good. Thus, the meter reading is governed by the condition of the poorest section. This method appl ies whether the two sections are alike or not. The only requirement is a separate cathode for each section. For dual- section tubes that have only one cathode, such as a 55U4, two separate tests can be made, or the two sections can be tested in parallel. Fig. 5 shows the same tube shown in Fig. 4, but now it is connected with the two sections in parallel. Notice that the neon lamp labeled SHORT will light if way to stock and sell the the tube has a cathode -to- heater short. The modern This is the most common type of short world's most wanted capacitors. This effi- found in tubes. This circuit follows cient shop -chest tells you what's in stock and exactly where it is. No the EIA standard of 1/2 megohm as the more digging for misplaced units. You get an assortment of the most maximum tolerable leakage resistance type twist -prongs, "Blue Beavers," and between heater and cathode. The sensi- popular C -D "Preferred" s you look more tivity of the SHORT indicator in this Mylar Tubulars -in handsome metal cabinets. Makes circuit is made a bit higher than 1/2 efficient...makes work efficient ! Best of all they're FREE with your megohm so that it starts to show a faint purchase of capacitors. flicker when cathode -to- heater leakage resistance gets down around 750,000 See the "Treasure Chest" at your C -D distributor or write for Bul- ohms. Still lower values of leakage re- letins to Cornell -Dubilier Electric Corporation, South Plainfield, N.J. sistance cause a brighter glow. The GAS indicator responds to high gas content in a tube as well as to grid - to- cathode leakage. The sensitivity of this circuit is set between 3 and 5 megohms. Looking again at Fig. 5, notice that a grid -to- cathode short will light both neon lamps if the resistance CORNELL -DUBILIER AUGUST, 1959 SERVICE CAPACITORS

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2K/3W-WW S4- QUALITY tiVN (IN SHORT POS)

.2 K 68K IODf,r11Mp DC ---/ (`/. iQ SHORT 100K ± 200n-wW 2K 0 200 r LOAD ^SAW-9-VNN SD ADJ NE-2

c Y X 4 5 y00 o II o O i I 9 Y X 820K X Y

WH RED YEL-GRAY BROWN

O FOR COLD CATHODE TUBES GRAY GREEN -YEL YEL-RED FILAMENT

BK (ó, WH-BL N o0 p O o OR a /SELECTOR 0- M 117 VAC E S2-c ó YEL F- F -oho= po. oC Go- R S3 ON BK GREEN ----0L o--. TOP c» B Hp CAP LOAD CONT BK-WH C7 A J K 0 O o BLUE

Fig. 7- Circuit of the Mini- Check, u 3- control 17- socket tube tester. of the short is less than % megohm. If to 17, without affecting accuracy. isolated from the other it is more than % megohm, elements and only the The key to the reduced number of returned to the lower end of the trans- GAS indicator will light. In tubes which sockets is in being able to connect have the former winding. The rest of the tube no indirectly heated cathode, such cathode return circuit to any tube base elements are as 1U5, 5Y3, 1B3, tied together and returned etc., the filament pin. In this way, the group of tubes to the grid end serves as the cathode, and of the transformer a short to with base -pin connections like the 6KG winding, and the tube is set up properly the filament will cause the GAS indicator can be expanded so tubes with their to glow. for an emission quality test. cathodes on some other pin besides pin 8 In the full circuit of the Mini -Check, The SHORT - QUALITY pushbutton can be tested in the same socket. For shown in Fig. 7, you can see the third switch on the Fast Check is an ex- example, in the 41- socket instrument section clusive Century of the cathode -selecting switch. design. It switches the 6K6 and 6BG6 use different sockets This adds to the dual -purpose tubes from instrument's versatil- the parallel because 6K6 has pin 8 as its cathode ity. The other two controls on hookup of Fig. 5 this in- to the series hookup and 6BG6 has pin 3 as its cathode. In strument are the same of Fig. 4. When as the two found the pushbutton is in its the Mini- Check, these tubes can be on the 41- normal position, socket version, namely the the tube sections are tested in the same socket. LOAD and the in parallel filament SELECTOR. The 17- and the tube is tested for In Fig. 8, we have a two- section wafer socket Mini -Check shorts. As soon as the does not require button is pushed, switch. Section A is a conventional one - switching dual -purpose the sections are in series tube sections and the tube pole eight -position wafer, while section from parallel to series, so the short is tested for quality. B is a shorting ring which shorts all quality The switch switch is less complicated. circuit in Fig. 6 is shown contacts except one. The arm of section This article shows in the SHORT that there are position. The circuit also A is returned to the cathode portion of many ways to get an accurate tube test shows various heater -voltage taps, the circuit, while the arm of section B with labeled a limited number of controls. It A, B, C and D. In addition, the is returned to the grid portion of the is even possible plate -voltage tap, to have an instrument labeled P, is shown. circuit. Tracing the circuit, you will with no controls at all, which would This tap is usually about 25 volts above see that the cathode of the pentode is ground. have as many sockets as there are types The meter and load resistance of tubes. are shown Conversely, as greater degrees at the input or grid portion of accuracy are required, more switches of the path which current takes during the quality and controls must be added until all the test, but the meter and load time -saving advantages are lost. could also be placed in the return or The two -control cathode path Fast Check and the without affecting the test. three -control Mini -Check tube testers represent the most popular 3 controls and 17 sockets 51I circuits used Another today in multiple- socket testers. solution to the same problem This relatively new way of testing is seen in the Mini -Check (see Fig. 7). CATHODES SWITCH tubes has earned a definite place in the By adding a cathode- selecting SWITCH SECTION B control SECTION A test equipment picture because is a (labeled FUNCTION it on the panel), the Fig. Cathode- selecting switch proven time saver. And more than ever, number of sockets is reduced 8- from 41 action. these days, time is money! END 94 RADIO -ELECTRONICS

www.americanradiohistory.com Technicians TECHNICIANS' look to Burroughs E for your successful future N S in electronics.

PHILCO SHOWS TECHNICIANS r Philco invited by first class mail during June and July 150,000 independent service technicians to attend distributor showings of 1960 home electronics products. TV sets were seen in operation with the back panels removed, and engineers in attendance to discuss technical and service features of the new receivers. In addition to electronics, Philco's home appliances were also demonstrated and examined. Over 100 such showings were scheduled over the country. First affair was in Shreve- port, La., on June 12. TEAM ELECTS INTEGRATED The annual election of officers for the Electronic Association of Missouri DATA PROCESSING (TEAM) in St. Louis put these men to work for the next year: W. C. Pecht, FOR MILITARY president; Stanley Siegel, vice presi- WEAPONS SYSTEMS dent; Arthur Mayer, secretary- treas- urer. CCTV LECTURE More than 300 technicians listened ...at BURROUGHS Military Field Service Division adds up to chal- to a talk on closed- circuit television by lenging work on important long range ATLAS and SAGE programs, Joseph Kerner of Blonder- Tongue Labs. performance and a fine career in Inc., at a meeting of CETA (Certified advancement based on individual Electronic Technicians Association) at the field of tomorrow: Digital Computation. the New York Trade School. CETA had invited other technicians associations in the area to attend, and many did so. BURROUGHS, consistent with its recognized leadership in equüp- After the meeting, lecture and ment, skills and manpower, is providing the answers for complex mili- question- and -answer period, Blonder - tary weapons systems through automatic suprahuman computation. Tongue presented some CCTV equipment to the school. CETA's president Bob Cornell also presented CETA's will receive: 1) Formal 16 to 22 -week training "plaque of devoted and distinguished Qualified applicants service" to Paul Zbar of the school. program in Data Processing Systems. 2) Starting salary commen- surate with experience and ability. 3) Full salary while training. PHILCO FIGHTS LOW RATES 4) Fine fringe benefits including educational assistance in addition The Massachusetts Joint Standing to your training program. 5) Current field assignments include West- Committee on Mercantile Affairs held a ern and Midwestern areas, when your training program is concluded. public hearing on a bill proposed to set a maximum fee of $3 for any service work performed on household appli- If you are a graduate of an accredited Technical School and /or have ances, including TV sets and radios. equipment, plus at Philco's service district representative military training in radar or communications for New England, Edward P. Burke, least 2 years' experience in electronics, you are invited to address appeared to speak against the bill. He your inquiries to Mr. A. J. Bel lace, Employment Supervisor, Department said that Philco felt the proposed law 2324, Military Field Service Division, Burroughs Drive, Radnor, Pa. was impractical and unrealistic. (a suburb of Philadelphia). "Limiting payment for service work performed on household appliances to $3 would seriously threaten the business in which Philco is engaged. It would jeopardize the convenience, safety and welfare of hundreds of thousands of users of appliances in this Commonwealth, and would work an extreme hardship on those citizens em- Burroughs Corporation ployed in servicing these products... "NEW DIMENSIONS/in computation for military s; 'ems" "In 1957, Philco (briefly) operated its own factory service branch in Boston. The minimum home call charge, not AUGUST, 1959 95

www.americanradiohistory.com TECHNICIANS' NEWS (Continued)

POLY During Lektron's 4 -Week including parts, was $5.95. Today Philco does not operate factory service PARS 1,000,000 Radio -TV Parts branches, but arranges for ... service FOR Free- For -All Sale! calls on a basis of a minimum labor fee 2 of $5. 1st Pak 2nd Pak "The law requires that labor shall be paid a minimum of $1 per hour. DISC CONDENSERS 30 for 880 FREE Certainly a man who must serve an ap- GERMANIUM DIODES 6 for 880 FREE prenticeship, acquire specialized knowl- MICA CONDENSERS 60 for 880 FREE 8 edge and maintain that knowledge and * $15 GEIGER COUNTER TUBE I for 880 FREE OF OUR skill by constant study man is * POLY BOXES 10 for 880 FREE -that MOST basically worth from $1.85 $2.50 TRANSISTOR PRINTED 15 to per CIRCUITS for 880 FREE POPULAR hour minimum. MICA CONDENSERS 50 for 880 FREE "By applying the accepted 100c/c to PLUG 'n RECEPTACLES 50 for 880 FREE POLY -PAKS 200% burden figure (burden to * STARRED ITEMS ON A WHILE-THEY -LAST BASIS AT THIS "2- for -1" PRICE. SUPPLY LIMITED refers i expenses such as rent, heat, light, etc.), we arrive at an hourly cost ranging POLY PAK OF YOUR CHOICE from $3.70 to $7.50 per hour ... "Because of the variety of circum- WITH EVERY $8 ORDER -ABOVE "2- for -1" Paks apply FREE! stances and kinds of service required 2 TRANSISTOR VARI. 70 TBLR COND'NS'RS 2 VARI- LOOPSTICKS 30 MOLDED COND'S'RS l i,g 2" haft. Papcr, molded, oil, Ad). 540 -15m) Ers. Philco Corp. is not in sympathy with Dual '341"';mf. porc.; to .a mf to 10,11) Transistor radios, msdli Wtherrlbs. 88c Wt. 1 lb. Reg. 5:3.00 s 88c Y. 2 lbs. Reg. $14 etc. I II,. 88cO 88c 10 ROTARY SWITCHES the principle of fixing a maximum fee MINI -RADIO KIT 4 OSCILLATOR COILS WIRE STRIPPER World's ss,td.Rlgm7in :1 for service work." Miniature. transistor. Strlpa, is xliì tidal smallest! 2 x 1 88c Covers 540 to X22 Itookttp s jacks, 88c diode, 1 etc. /Instlrtm'- 40 PRECISION RESIS. 1000 kcs. Reg. $4.00 Wire. Wi. 1 Ib. 88c tions. 1 lb. ttL Reg. $3. 88C Carbon, W.W. wide vo- 3 TRANSISTOR XFMRS 10 ELECTROLYTICS 1.2 PHILLY TECHNICAL MEET 100 RADIO PARTS w.W. 1 lb. Reg. $19 88C Submini. size. 1011's of Radio, TV. 10 -50 mf Wide variety resistors, is to Reg. condensers, pots, 5 -IN -1 DRILL BIT stage1 etce Reg. $1l1 3 lbs. Reg. $12 88c forms. 3 lbs. 88c Reams, .s:o.'s, pes, Electronic servicing was the keynote 188c shapes, drills: 100 RESISTORS 60 RADIO -TV KNOBS hand or ism, ,b'iOn of the Electronic Technicians Forum Carbon and precision: Asstd. colors, insola n tton. Some ort), $1 40 SUBMINI RESIST'RS held in Philadelphia 12, 13 ea. 2 lbs. Reg. $17 1/ long. ANSI- values. June and 56 ohms to megs. 88c W 3 lbs. Reg. $25.00 88C l/ to li) 14. The forum, held 16 -END WRENCH SET megs. Reg. $6. 88c under the auspices POWER TRANS. P -N -P For honte N.-i.51/114t1,. Roz 5" HOBBY SPEAKER of the Television Service Association of 10W rating: for audio. & open' lhru For radios, ode auto. other s leg $ 16 sizes, 88G. intercoms. 2 88`. Delaware Valley, was a too. Reg. $10.011 SSC Reg. $2.50 88c lbs. Reg. $5. attended by 35 TWO -WATTERS 70 ONE -WATTERS 4 POWER WOOD BITS number of industry representatives AseTtods ('arbor resl.stms: 1. value re- Ri -Q steel. 3/a, 12, 3 carbon 1 ". . ' other than service technicians, and 1 . Reg long. r $12 88c Sis. 88c 88C Reg. FREE! several demonstrations and displays 000 -999 COUNTER 10 TUBULAR ELECTROS FULL YEAR'S weeder-Root. Automat- Asstd. paper types. AC, were staged in the meeting hall in addi- ic reset. Motors. 88C DC. Hobby. foils. etc. Reg. $5 FREE! 3 lhs. Reg. $15. 88c SUBSCRIPTION tion to those given in connection with 12 -HR. SPACE CLOCK GIFT 20 ARTISTS BRUSHES to Lektron's Powered by partite bat. SURPRISE 100 bristle: "Family Shopper" the talks. s izes 1 -8 pure tery. ß oz. Hab- 88C b)dsts. note! Reg. .58 88c FREE WITH Reg $2.50 The discussions and demonstrations 8 RCA PLUG -N -JACK TEN SECOND TIMER SUN BATTERY EVERY ORDER! Sets, matched. Most 3- included electronic cooking and elec- Similar to famed R_M. pop, amps, Mechanisms: precis ist l' long51) , ge:lred. 2 R,.. Beg. $2. 88c tuners, phonos. 88c Reg. $'30 88c tronic refrigeration, ultrasonic washers, 2 NPN TRANSISTORS 60 TERMINAL STRIPS HEARING AID PHONE Solder 6 SILICON DIODES closed -circuit TV, transistor circuits -lug y binding. ) 1AJ2. cry=tmIrtie7,l.; t n`Ja1 ;dip:" 88c 10 types. 2 1L.. S'Iani:l & lug. Reg. $- 88c 88e 12v3. Reg. .ses 88c and servicing, and no less than three XFMRS 35 POWER RESISTORS 60 COILS. CHOKES $25 SURPRISE PACK! 4 OUTPUT tt W. 1, to Lsrge, v:, ed assort. discussions of printed circuitry, includ- t IF, lil , .nt., 'lug 50L1ì, tc. 3 11,.. 111. , 1,ohmc. J\'llrcnus, Reg. $8. 88c too. 3 II,. tl"i,, II too! 88c parts. ' :1 1 b .. 88c ing recent developments and methods of Reg. $ Reg t$15ó POSTAGE STAMP MIKE 7- SCREWDRIVER SET c HOBBY BENCH VISE servicing printed boards. Of the 14 Crystal, loll In into 40 HI-9 CONDENSERS type. Fits ta- 7 std. drivers sv /,call cps. 1 Ib. o rack. Plastic hampes. Reg. 88C Cla s, É o 1 ]b talks, only 3 were specifically confined $7. NPO's, too! 1 lb. !88c 88c 1 Ib. List 88c 40 TUBE SOCKETS Reg. $15. 300 -FT. HOOKUP WIRE $3. to entertainment electronics, one a dis- 4 ramiC, 5 ROLLS MICRO -WIRE Tinned, asstd. ize., 40 S50 UBMINI COND'SRS ira, shield -base 88C }r 24 titi' :32: fo r tea n- colors. 2 lbs. 88c For.transis cur. printed cussion' and demonstration of an elec- Incl.' 2 lbs. Reg. $10. istor. :ub -mi ni Reg. $5 circuit work. 1 lb. Reg. 88C circuits. 1111. 88c 100 HALF -WATTERS $7 2 TRANSISTOR IF'S 1500 PCS. HARDWARE tronic organ, one on record changers Doube- tuned, Only 8í8C" 15 -PC. DRILL SET Asstd. value carbon e- square. 156 ken, slstors, incl. Nul.v, WIti and one on color TV installation and 64ths, . - 5.. Reg. $12 88C lseT w %calibratedr/ Reg. $6. 70 HI-9 RESISTORS case. Reg. $3 88C 75 RESISTOR SPECIAL! servicing. Business methods that pay I lated carbon: WW, eclsion, carbon, 60 CONDENSER SPCL! o o! l/x 1w, 10 ohms 10 VOLUME CONTROLS variable, mini types. paper c le, off were also covered, and the tech- 3 t0 10 megs. 2 lbs. Some w/switches. lbs. Worth Molded,oil, mica, discs, c 188C Reg. $13. 88c 3 lbs. Reg. $9 88c $15 88c variable. 2 lbs. nicians were even given a preview of ORDER BY BLACK -TYPE HEADLINES TV as it may be 20 years in the future. HOW TO ORDER'' i.e., 30 DISK CONDENSERS 88c. State price with each item. Send check or M.O. including 131 Everett Ave. The Pennsylvania State Federation sufficient postage; excess returned. C.O.D. orders. 250% CHELSEA 50, MASS. of down; rated net 30 days. INCLUDE POSTAL ZONE in address. radio and television service associa- (Canada postage, 48c, 1st lb.; 28c ea. add') Ib.) LEKTRON tions met during the forum. The dele- gates explored plans for further extend- ing and improving cooperation with the state broadcasters' association in SENCORE o use selling the radio receiver owner on the safe" idea of keeping his radio in trim. CIRCUIT Objective was an intensified campaign I TESTER next May, the broadcasters' Radio Month. Attendance at the Friday and Satur- day sessions of the forum was light, Save costly call backs by testing the circuit before replacing fuse, fuse resistor or circuit breaker. but more than a hundred turned out to - Individual scale for each value fuse resistor -no interpretation, view the Radarange cooking, the closed just read in red or green area. C"-- MODEL circuit TV and other demonstrations * Measures line current and up to 1100 watts of power at 115 volts FS -3 and talks Sunday. The banquet Satur- using line cord and socket. * Two convenient current ranges- day night was extremely well attended, () to 2 amps and 0 to 10 amps. Test leads clip in place of fuse not only by technicians and their wives or fuse resistor.* 5 ohm, 10 watt resistor prevents 8 DEALER NET TVcircuit damage,simulates operating conditions. AC -DC or both as needed but by representatives of the manu- fer Fuse Resistor As Recommended by Leading Manufacturers At facturing and distribution fields. Circuits Leading Donald SERVICE INSTRUMENTS CORPORATION Parts H. Stover of the Industrial Relations Ll 121 OFFICIAL ROAD, ADDISON, ILLINOIS Distributors See other SENCORE ads in this issue Min -fa (Continued on page 100)

96 RADIO -ELECTRONICS

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www.americanradiohistory.com SHIPPED ON APPROVAL CONDENSER TESTER MINI -CHECK TUBE TESTER IN-CIRCUIT Model MC -1 CT -1 Model A Real ECONOMY FOR AN ABSOLUTE 'MUST' MULTIPLE SOCKET EVERY SERVICEMAN! TUBE TESTER without condenser tester fib Here is an in- circuit ac- sacrifice in ACCU- the whole job. The CT -1 that does over where RACY, SPEED steps in and takes or VER- s V. tually testersr in- circuit condenser all other oftf a SATILITY fail. The ingenious application ®*** gives o CT 1 a Here is a multiple socket tube °. dual bridge principleP tester designed El ® of operation. . . to meet limited tremendous range budgets. Although low in price it t ». boasts a unique circuitry that enables you to check over 600 tube checks: types - and has a range of opera- ¡n- circuit tion that far exceeds others in its of all condensers price Quality of over. 80% pres- class. _s- eve circuit opens, intermit- a ka shorts, Model MC -1 housed ent ( sturdy - in tents) mmfd. wrinkle finish steel $3950 SIZE: W-9" condensers from 200 case Valuelue offfadll H-81/2" Model Net all electrolytic condensers in sturdy D -23/4" Quality a charge) fin- (the ability to hold hammertone SPECIFICATIONS and wiring leakage case $50 Checks socket ism steel emission, inter -element shorts and leakage of Transformer, complete with Net This covers OZ4s, series -string over 600 tube types. capacityCapacity TV tubes, gas regulators, auto 12 plate volt, test leads hi -fi and foreign tubes 3 settings enable W D-31/4, 10 a test of any tube in less than SIZE: -6 H-7" seconds Employs dynamic cathode emission test principles D'Arsonval type meter most accurate 31/2" circuit checks: and inter- tivity - type available ... its greater sensi- out -of- shorts, opens means more accuracy ... its jewel bearing means . (leakage, lasting phosphor longer life 17 long of 100 /o of all condensers bronze tube sockets Combination gas Quality indicator 9 filament positions and short jewel mittents) mfd. Handy tube chart contained in special back mittents) from 50 mmfd. to .5 compartment New tube listings furnished periodically of all condensers to hold a charge) tachable line cord at no cost De- Value condensers ability Quality of all electrolytic up to (the and wir- v High resistance leakage socket, component condensers ... transformer, these New unknown p¡uS BONUS FEATURES ... found ing le r in no other low price tube tester SPECIFICATIONS Multi -color direct drift -free circuitry Checks for cathode to heater shorts Checks Ultra-sensitive 2 tube for gas content qreadingsand and Checks all sections of multiple purpose tubes ... will pickup precision re dSimultaneous of circuit capacity with one tubes over 300 "Bad" section Line isolated - no shock hazard or out circuit) indicator sensitive to able load control Vari- oBuilt -in hi- leakage Electronic enables you to get accurate results on all tubes circuit resistance components Positively cannot become obsolete Isolat ppower line as new tubes are introduced. even greater accurcy balance indicator for TRANSISTOR RECTIFIER TESTER IN-CIRCUITUIT Model SRT -1 TESTER 17-1l power rectifiers AN INEXPENSIVE Checks all QUALITY INSTRUMENT in-circuit PENDABLE DE- TESTS OF ALLATRANSISTORS AND DIODES SELENIUM. 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Now is TRANSISTOR need for icon power rectifier tester TESTER is great. for an greater than e SPECIFICATIONS AU POWER SRT -1 CHECKS Checks all THE OUT - car transistors, including CIRCUIT AND radio, power output, RECTIFIERS IN- rode and unijunction triode, tet- EFFECTIVE- rent types for Model WITH 100% gain, leakage, opens, cur- TT -2 housed OF CIRCUIT off current shorts, cut- in sturdy hammertone- forward Checks all diodes to reverse for finish steel case NESS FOR: tests corn- Opens can ti e made plete with test leads Shorts furors' cevennifgmanufacll Net Quality Fading rated Expectancy Less than half SIZE: Life tests ammute equiredefor Vi-6'' H -7" D -3+ Arcing of either transistors a yet rugged or diodes Large SRT-1- moused . with multi -color 3, meter Model D-31/4" Power is supplied scales designed sensitive hammertone H-7" by an easy squick easy in sturdy SIZE. W-6,, to replace 6 -volt drain Net batteryeryY current test leads $v 950 due toaalécidental shortshorting shelf - drain plete with damage transistor of clips or diode under burn- outts wnemeter enable tests without test Long test leads or leads are entirely removing and insulated test 500 ma. (selenium, identified by E.I.A. transistor from SPECIFICATIONS10 ma. to terminal is assured color code so that circuit Test rated from chart Comes complete connection to the of rectifiers or out-of-circuit. that fits into a with replaceable correct all types power both in-c special rear compartment. transistor set -up Checks silicon, etc.) dead short. germanium, connected to a even when rugged. IMPORTANT blow fuses sensitive yet FEATURE: The TT -2 cannot Will not -color meter ... you to check become obsolete as accurate multi tests. will all new type transistors Large 3" highly out -of- circuit be furnished periodically has they are introduced. for in- circuit and at no cost. New listingsstinbgs meter scales tested. I Separate rectifier being or over heat test. right Cannot damage under circuit. test leads oone rectifieri from dust clip. cu s s re on the l indication TO in the circuit w instanti EA Y TO BUY IF FIED SIMPLE Press meter scales.. SATI r ead three -color OPERATE -tó

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ffW PetakytOp Peark VACUUM TUBE Model WITH VOLT METER VT -1 LARGE EASY -TO -READ 6 METER featuring the - sensational new MULTI-PROBE Patent Pending No extra probes to buy! The versatile MULTI -PROBE does the work of 4 probes o DC Probe Q AC -Ohms Probe © Lo -Cap Probe O RF Probe The VT -1 is a tremendous achievement all the in test equipment. With its unique MULTI jobs a V.T.V.M. should do without the expense -PROBE it will do have to cart around of buying additional probes. No a maize of entangled cables, lose time alternating longer do you placed probe. With just a twist of the cables or hunting for a mis- saving jobs. MULTI -PROBE tip you can set it to do any A special holder on side of case keeps one of many time- MULTI -PROBE firmly in place ready for use. FUNCTIONS OUTSTANDING DC VOLTMETER FEATURES Will measure D.C. down to Completely portable self 1.5 volts full scale with minimum batteries - powered with long life and circuit loading, - permits use everywhere New advanced pentode amplifier circuit assures s .025 l amazingly low vaccurate illa measure low1AGCVandnoscillator drain Large 6'- 100 -microampere battery bias voltages from .1 meter, many times volts or less up to 1500 volts more sensitive than meters used in most with consistent laboratory accuracy Laboratory accuracy V.T.V.M.'s Zero center provided on all ranges ... performance - 2% of full scale for all balancing measurements on DC, 5% of full scale on AC Simplified such as discriminator, ratio detector easy -to -read 4 -scale multi -color hi -fi amplifier alignment and meter No heat operation assures balancing. rigid stability and accuracy Immune fluctuations Amplifier to power line AC VOLTMETER compensated rectifier circuit with frequency ... True Peak -to -Peak measure- attenator a feature found ments as low as 3 volts of any laboratory instruments - only in costly TV wave form including Meter completely isolated sync, deflection voltages, video pulses, distortion practically burn -out proof - in hi -fi amplifiers, AGC eliminates Hand- crafted circuitry and color TV gating pulses ... the service headaches of printed Scale divisions are easily read down 1% resistors used circuitry Measures to .1 volts . for permanent accuracy Separate RMS at 1 /20th the circuit RF ground return for loading of a low -loss RF measurement Micro- ... Unlike most other V.T.V.M.'s there is phone type co -axial connector loss in accuracy on the lowest no tects instrument Matching cover pro- AC range. face - snaps on and off instantly. ELECTRONIC OHMETER .. Measures from to 1000 megohms Scale o down ... divisions are easily read to .2 ohms ... Will measure resistance values SPECIFICATIONS from .2 ohms DC to one billion ohms . . Will Volts 0 to 1.5/6/30 Model high resistance leakage detect - 150 300/600/1500 volts VT -1 - full' wired and in electrolytic and by -pass AC Volts (RMS and Peak -to condensers. -Peak) - 0 to 3/12/60;300'1200 volts calibrated, housed in hand- Ohms - 0 to a billion ohms, 10 ohms some hammertane finish RF 100K /1M center scale - Rx1 /10 /100 /1K /10K/ steel and LO -CAP MEASUREMENTS case, complete o.. th . RF Peak MULTI - With these extra VT -1 - reading demodulator PROBE,and functions you can measure supplied for use on all DC ranges thor- voltages in extremely high -impedance Zero Center available on ough instruction as sync and AGC circuits such Decibelsbels pulses, driving saw Dbto+10,22,36l manual covering color TV tooth voltages, IMW /50 ;621tbased on the Dbmeunit: 0Db- 5 gating pulses, mixer output levels, in 600 ohms stage by -stage gain and I.F. Impedance detector inputs. 11 megohms DC, 1 megohm fions in Net Input - AC, 10 megohms Lo -Cap detail.ca Capacity - 130 mmfd. RMS, 250 mmfd. Peak -to -Peak, 25 mmfd. Lo -Cap FAST-CHECK TUBE Fc -2 Simply set two controlcontrols TESTER ... insert tube ... and press any of over 700 quality button to test tube types completely, accurately ,0 ... IN JUST SECONDS! servic2in0g in r einvcerry by selling imnoinw tunsg unprofi r more tubes with very little cHaECbKackstand their chose the FAST -CHECK effort. See for yourself at laar earnings above all other tube testers. no risk why so many servicemen PICTURE TUBE TESTADAPTER INCLUDED WITH FAST -CHECK RANGE OF Enables you Checks OPERATION to check all quality of over 700 tubes picture tubes (including proven dynamic cathode types, employing the time the emission test. This covers new short -neck 110 more than degree type) TV tubes, autoe12nplate- voltytubes. series-string for cathode regulators, special emission, shorts and purpose hi -fi tubes and expectancy...also life Checks for inter -element shorts even foreignetubes. to reju- Checks for gas content. and leakage. venate weak picture tubes. Checks for life- expectancy.

No time consuming on conventional multiple switching testers No annoying settings are required located inside cover. roll chart checking tang banks tion of New listings are added listing switches multi- section tubes and without costly roll tube SIZE: W- 145/8" 41 phosphor if only one section chart replacement H- 111/4" D_43'8" bronze beryllium tube is defective the tube hw Cheeks each sec- mounted on panel Large sockets never need ll "Bad" outheu meter protected 41/2" D'Arsonval replacement 7 -pin pscale Model against accidental type meter is the and 9 -pin straighteners FC -2 housed in line voltage burn -out Special most sensitive available, rubbed - hand - variation 12 filament scale on meter for yet egged fully oak carrying case corn- no shock hazards positions Separate low current tubes - plete with CRT $LQ5o Long lasting etched gas and short jewel Compensation for adapter The aluminum indicators Lile isolated Net NOTE: Fast -Check positively cannot - all future become obsolete . tube types as they come out. New tube listings are fury shed periodicallylyc at no cost. CONVENIENT IME PAYMENT PLAN - NO FINANCING CHARGES MIMI ------ALL CENTURY ---- INSTRUMENTS ARE FCIENTURY ELECTRONICS CO., INC. 108, New York GUARANTEED FOR CHECK INSTRUMENTS DESIRED 111 Roosevelt Avenue, Dept. Mineola, free trial. It sa :isfied I agree to pay IIModel CT -1 In- Circuit Condenser Tester $34.50 Please rush the instruments checked for a 10 day ONE FULL YEAR the down payment within 10 days and the monthly instaltmerts as shown. If not 1 $9.50 within 10 days. Balance $5 monthly for 5 months. is no completely satisfied I will return the instruments within IC days and there The extremely low Model MC -1 Mini -Check Tube Tester $39.50 further obligation. It is understood there will be NO INTEREST or FINANCING I $9.50 within 10 days. Balance $6 monthly for 5 months. charges added. prices are made n Model SRT -1 In- Circuit Rectifier Tester ...... $29.50 I I $4.50 within 10 days. Balance $5 monthly for 5 months. possible because Model TT -2 Transistor Tester $24.50 Name Please print clearly you are buying di- 1 n $4.50 within 10 days. Balance $5 monthly for 4 months. n Model VT -1 Battery Vacuum Tube Volt Meter $58.50 $14.50 10 Balance $11 monthly 4 months. Address rect from the l I within days. for Model FC -2 Fast -Check Tube Tester. $69.50 manufacturer. $14.50 within 10 days. Balance $11 monthly for 5 months. City State Prices Net F.O.B. Mineola, N. Y. www.americanradiohistory.com TECHNICIANS' NEWS (Continued from p. 96)

Department of EIA was the principal caught fire on the Thruway and we speaker. never got there at all!" ESFETA REPORTS GROWTH KENTUCKY ASS'N ELECTS The Empire State Federation of The Kentuckiana TV & Radio Tech- Electronic Technicians (ESFETA) nicians Association (KTRTA) elected welcomed its 14th affiliate to membership with the attendance of Leonard Block, president of the newly affiliated North Tonawanda group at the last meeting of ESFETA. In 1955 there were just 7 affiliated groups. At the meeting in Syracuse the present officials were all re- elected : Robert Larsen, president; Irving Toner, vice as officers (pictured above in the usual president; George Carlson, secretary; order) at their regular meeting Ira Dan Hurley, treasurer; Frank Kurow- Masden, vice president; George Leitner, ski, sergeant -at -arms. Writes George, treasurer; Giles Allen, president; Bud "I missed the meeting because our car Pilkington, treasurer.

:::::..:::::::::.::::::::::::::. :.::::::::::::::::::.::::::::::::.:::::.::::::: :::::.::::::::::::::::.,:::::::::::::::,,::::,::::::::::::,:,:::::::::,:,,:::::::::::::::::::::::::::::::::::::: :, ::,:,:::::,,U: ,:::::::: DO YOU BELONG TO A SERVICE TECHNICIANS' ASSOCIATION? For the benefit of service technicians KANSAS and their organizations RADIO -ELEC- TELEVISION ELECTRONICS SERVICE TRONICS is beginning a complete ASSOCIATION OF KANSAS, INC. list P.O. Box 154 of the known televison service associa- Ellinwood tions in this country and Canada. Due E. A. Redmon, Secretary to the difficulty of contacting associa- MICHIGAN tions, our first list will necessarily be TELEVISION SERVICE ASSOCIATION OF MICHIGAN incomplete and sometimes inaccurate. 8225 Woodward Service technicians can help us put out Detroit 2 a complete up -to -date list. If you know Michael Graham, Secretary of any association omitted from our list, MINNESOTA ELECTRONIC or can correct any of the old MINNESOTA TELEVISION SERVICE listings, ENGINEERS, INC. please also write to: Associations Edi- Box 4429 TECHNICIANS tor, RADIO- ELECTRONICS, 154 W. Minneapolis 14th St., New York 11, N. Y. Warren Schei, Secretary immediate opportunities with MISSOURI This month we start by publishing a list of ELECTRONIC ASSOCIATION OF MISSOURI MAMO known state associations; there- 4134 Easton Ave. WOOLDRIDGE after we will list a number of local asso- St. Louis ciations each month. If there is a group Robert Lucas, Secretary Expanding commercial and military proj- near you, why not contact them? It's for NEW HAMPSHIRE RADIO ects Ramo- your AND TELEVISION ASSOCIATION at Wooldridge in Los Angeles benefit. OF N. H. have created a wide variety of perma- To learn of the association nearest 334 Mitchell St. you now. Manchester nent opportunities for Electronic Tech- drop a postcard to: Associa- Emile R. Gelinas, Secretary nicians. Selected candidates will work tion Editor, RADIO -ELECTRONICS, NEW YORK 154 closely with scientists and engineers W. 14th St., N. Y. 11, N. Y. EMPIRE STATE FEDERATION OF ELECTRONIC TECHNICIANS, INC. engaged on some of the most advanced ARIZONA 19 West Cowden Place Jamestown research and development projects in BETTER ELECTRONIC SERVICE TECHNICIANS OF ARIZONA George Car/son, Secretary the nation. Box 1284 NORTH CAROLINA Phoenix NORTH CAROLINA FEDERATION OF ELEC. Technicians qualified by experience and David Gordon, Secretary TRONIC ASSOCIATIONS, INC. training in one 520 E. Main St. or more of the listed ARKANSAS Durham areas are invited to investigate current Charles S. Mcßroom, Secretary TELEVISION SERVICE ASSOCIATION OF openings at Ramo- Wooldridge. AMERICA OHIO Box 542 TELEVISION ELECTRONIC North Little Rock SERVICE BREADBOARD BUILDUP ASSOCIATION OF OHIO W. D. Todd, Secretary 2552 North High St. EXPERIMENTAL CIRCUIT TESTING Columbus CALIFORNIA William Hetrick, Secretary PROTOTYPE DEVELOPMENT RADIO TECHNICIANS ASSOCIATION OKLAHOMA Box 4085 DIGITAL COMPUTER CHECKOUT TELEVISION SERVICE ASSOCIATION OF Long Beach 4 OKLAHOMA DIGITAL -TO-ANALOG CONVERTERS Harry Ward, Secretary 2908 N.W. 23rd St. Oklahoma City 7 MAGNETIC RECORDING DEVICES SOCIETY OF RADIO AND TELEVISION TECHNICIANS Roy Allen, Secretary TRANSISTORIZED DIGITAL CIRCUITRY Box 126 PENNSYLVANIA Van Nuys RADAR SYSTEMS FEDERATION OF TELEVISION -RADIO SERVICE Wally Crusan, Secretary ASSOCIATIONS OF PENNSYLVANIA, INC. MICROWAVE EQUIPMENT 67 South Main St. CONNECTICUT Carbondale Leon J. Helk, Secretary Please send a complete resume, includ- TELEVISION ELECTRONIC SERVICE ASSOCIATION OF CONNECTICUT RHODE ISLAND ing present earnings, to 91 Huntington Rd. RHODE ISLAND RADIOMEN'S BUSINESS Stratford ASSOCIATION Mr. R. C. Chappel Robert A. Steer, Secretary 425 Wilert Ave. P.O. Box 90534, Airport Station Riverside 15 FLORIDA Edward J. Oliver, Secretary Los Angeles 45, California TELEVISION ELECTRONIC SERVICE TEXAS ASSOCIATION OF MIAMI TEXAS ELECTRONICS ASSOCIATION 119 N.W. 12th Ave. 810 East Commerce Miami 36 1 RAMO -WOOLDRIDGE San Antonio Max Reiser, Secretary A DIVISION OF THOMPSON RAMO WOOLDRIDGE INC. Will A. Shaw, Secretary 1111 II II, 1111 II 100 RADIO -ELECTRONICS

www.americanradiohistory.com Typical operating characteristics of IMPORTANT NEW NEN'L this Sylvania tube are: VH 18 SAMS BOOKS VP 100 VG2 100 TUB[S"aid gm (µmhos) 4,100 RP (K ohms) 250 "Television Antenna Handbook" Other tubes in this series are the 18FX6, dual- control miniature penti- by Jack Darr grid amplifier; 18FY6, hi -mu triode A practical guidebook for SEmI- double diode; 32ET5, beam power pen- the antenna installer and serviceman. Thoroughly tode; and a 35AM3, half -wave rectifier. covers the requirements All in a 7-pin of each reception area are packaged standard (primary, secondary, COODUCTORS fringe and far -fringe). Chapters include: The TV Signal -From Trans- G2 mitter to Receiver; Char- acteristics of Basic An- tennas; Commercial TV G3 Antenna Types; Transmission Lines; An- tenna Rotators; Planning the Installation; THIS month's releases are high- On- Location Tests; Tools and Equipment; GI lighted by a series of triode -pen- Towers, Masts and Guying; Roof -Top Tech- 18FW6 niques and Safety; Installing Antenna and tode tubes designed as combina- Lead -in; Noise, UHF and Color; Unusual tion voltage and power amplifiers, miniature envelope and are designed Installations; Servicing the Antenna Sys- tem. Most complete and practical book avail- plug -in silicon rectifiers as direct re- to be directly interchangeable with con- able on the subject. Illustrated; placements for mercury-vapor 866's, ventional 150 -ma prototypes. Of course, 248 pages; 53 x 83g; only 6395 a 24 -inch picture tube for cathode - when substituted in a series -string drive circuits and a miniature power receiver, all the tubes would have to amplifier tube delivering 24 watts per be changed at the same time. "Photofact Television Course" pair with low grid drive. All -New 2nd Edition 6FY8, 12FY8, 25FY8, 50FY8 Completely revised edi- I8FW6 New miniature triode -pentode tubes tion of the famous Course A miniature semi-remote -cutoff pen- combining voltage and power ampli- which has helped in the training of thousands of tode in a 7 -pin envelope, it is the first fiers. A pair of either of these types successful technicians. of a series of tubes to have 100 -ma are the only tubes required in a stereo Covers the complete sub- heaters and is designed for use in ac- ject of monochrome TV amplifier using the CBS modified sim- in three unique study sec- dc radios in rf and if applications. plex (two -way) circuit. (See diagram.) t ions. The emphasis is on the practical theory and operation of receiver circuits. Each section is built around a requirement of the picture tube, until every circuit in the TV receiver is covered. The course includes step -by -step descriptions of the functions of all important circuits, supported by many schematics of actual commercial circuits. Clearly written for easy understanding. The ideal course for students, service newcomers and hobbyists. Fully illustrated; 192 pages; ßb4 x 11 "; only 5395

"Video Speed Servicing" Vol.3 Latest volume in this valuable reference manual series. Presents 456 practical troubleshooting hints that will cure hard - to -find faults in some 87 chassis of late -model TV receivers. All models are indexed by brand name, SUITS NEED PRESSING - model and chassis number for quick reference. MERIT DEFLECTION YOKES An invaluable aid for shop bench use; each B ock numbers of most issues of 1 ,DO NOT hint is accompanied by Merit deflection yokes are cosine wound an explanatory diagram or schematic. 160 pages, 8% x 11 "; only $295L RADIO -ELECTRONICS TO FORM. not pressed. Pressing can lead to distortion poor focusing. a re available upon request and Pressing after winding frequently HOWARD W. SAMS & CO., INC. breakdown. This year's issues 35c causes Order from your Sams Distributor today, 11 MERIT COILS AND TRANSFORMERS or mail to Howard W. Sams & Co., Inc., Dept. H -29 Last year's issues 40c 2201 E. 46th St., Indianapolis 6, Ind. HAVE "BUILT -IN" ADVANTAGES. Send me the following books: Previous year 45c, etc., "Television Antenna Handbook" (TAD -ll "Photofact Television Course' (TV -2) up to a maximum of $1 per copy. Each Merit yoke is "Video Speed Servicing" (VSM -3) 100% LIVE TESTED All January TV issues 50c $ enclosed. Send Free Book List

COMPARE IT WITH Name Radio- Electronics MERIT Address MERIT COIL ANO TRANSFORMER CORP. 154 West 14th St., New York 11, N. Y. LCity Zone Slcle_ MERIT PLAZA HOLLYWOOD, FLORIDA - me (outside U.S.A. priced slightly hig'IelmiNIBENI AUGUST, 1959 101

www.americanradiohistory.com NEW TUBES AND SEMICONDUCTORS (Continued)

6FY8, 12FY8,25FY8 OR 50FY8 (2)

New CBS SC-2 .02 STEREO CARTRIDGE PROFESSIONAL 55 the Ultimate

STEREO CARTRIDGE

6FY8 1254 GIP 12FY8 25FY8 tube is operated with an ultor voltage K,G3p 50FY8 of 16,000, and with grid 2 at 50 volts, it requires no more than 47 volts of video drive from raster cutoff. Under This amplifier delivers up to 3.5 watts these conditions, the minimum ultor output per channel. Secondary imped- current at zero bias is 1 ma. The elec- ance of T1: each side of center tap tron gun used in the RCA 24BAP4 equals impedance of one speaker. Sec- requires no ion trap. The directly viewed ondary impedance of T2 is half the tube uses magnetic deflection and low - impedance of one speaker. For con- voltage electrostatic focus. It is a rec- struction data on this type amplifier, see "Two -Way Stereo Amplifier Uses CLhULTOR Only 3 Tubes," June, 1959, page 52. G4 COLUMBIA Heater currents for these CBS -Hy- C tron 6.3 -, 12.6 -, 25- and 50 -volt tubes G2 GI are 1.2 amps, 600, 300 and 150 ma, Professional 55 ... respectively. Typical operating char- GI Cost $28.95 acteristics are: Triode Pentode H This new transparent cartridge is the professional's version of the VP 125 125 24BAP4 popular Columbia 'M. A high -com- VG2 125 pliance model w th excellent tran- VG, (neg) 1.5 13.5 tangular tube with a spherical Filter - sient response, is rises a .5 -mil dia- IP (ma) 2.5 50 glass faceplate and an aluminized mond stylus and is designed for IG2 (ma) 10 screen. transcription turntables. Comes 2,000 7,000 Maximum design -center ratings for complete with 4 miniaturized plug - R, (ohms) 2,000 in equalizing networks for low- and this picture tube in cathode -drive serv- high -level inputs. PP (watts) 2.7 ice are: V; (rms) 0.3 Vir°r-GI (max) 20,000 CURVES, FACTS AND FIGURES PROVE IT Silicon 866 replacement (min) 12,000 VG4-GI (pos) 1,000 High -voltage silicon rectifier car- (neg) 500 tridges, rated at 6,400 piv at 250 ma, VG2 -6' 64 mounted with cooling fins on a 4 -pin VK -GI (pos peak) 200 tube base replace mercury -vapor 866's. (pos bias) 140 As well as replacing the 866's, the (neg peak) 2 (neg bias) 0

Miscellaneous The 7326, a 10 -stage head-on multi- plier phototube; the 7203/4CX250B, a forced- air-cooled beam power .tube for frequencies up to 500 mc, and the 6DE4 and 17DE4, damper tubes for 110° TV receivers have been announced Ask for Bulletin E -331. Check the Professional 55's superiority in: by RCA. linearity . . separat on ... needle Vacuum Tube Products Co. has a point impedance.. low mass ... new series of thyratrons that incor- freedom from hum and distortion ... output level...and ruggedness. porate new grid and filament design to 2.5 -volt filament transformer needed permit a 30% increase in peak anode YOUR OWN EARS PROVE IT for the tube is eliminated. No warmup current. Better still. Your owr ears will con- HPA -2800 and HPA -2810 are Hughes vince you the Pro'ess time is required -high voltage can be -oval 55 is applied immediately. Heat generation Aircraft diodes intended for uhf and your best investment. Ask to see a and hear it at your distributor's is only 6.5 watts. The new unit is made microwave applications. Both have today! by International Rectifier. nominal frequency cutoff of 70,000 mc with a nominal CBS ELECTRONICS at maximum back bias zero -bias capacitance of 2.5 µµf. A Division! of 24BAP4 -cell which Columbia Broadcast -rg System, Inc. Silicon solar modules Danvers, Massachjsetts This 24 -inch picture tube is designed interlock to form larger units are Rectifier. Distributed it Canada by for use in cathode -drive circuits. It has available from Internation CANADIAN GENERAL ELECRIC CO., I.TD., TORONTO an electron gun that has improved The firm has also released a line of cathode drive sensitivity. When the 1,500 -piv 300 -ma silicon rectifiers. END

102 RADIO -ELECTRONICS

www.americanradiohistory.com driven element gets broad -band radio vibrator supplies 8 or 12 frequency characteristics with volts. Microphone saT'plied.- gain of colinear antenna. Poly- Heath Co.,Benton Harbor, Mich. styrene insulators have dual TRUCK RADIO. Universal moisture barrier with 31/2-inch auto -boat -truck aiodeí ka radio. leakage path. -Winegard Co., 3000 Scotten, Burlington, Iowa. 3 -BAND CUBICAL QUAD ANTENNA, model MK III De- luxe Quad. 10, 15, 20 meters.

6 tubes, tone control, available for 6- or 12 -volt systeai$. Hangs TOOL KITS with interchange- from antenna -mounting hole in able bits for Allen hex screws roof, may be mounted in or and fluted -spline recessed screws Gain 10 db, 10 and 15 meters; under dashboard. - American are models ZA40 and ZF40, re- Television & Radio Co 300 E. 8 db, 20 meters. Turning radius 4th St., St. Mina. 9.5 feet. 27 lbs. Boom 2 inches Paul, x 8 feet long. -Cubex Co., CITIZENS' BAND RADIO Altadena, Calif. transceiver model ED-27 for 27 -mc band. 10 tubes; leansistor CITIZEN'S BAND KIT, trans- power supply. Works on 110 ceiver model CB -1. on Operates volts ac and 6 or 12 veils dc for any of 23 channels with crystal mobile. Receiver double- conver- Tests new short -neck 110° sion superhet, crystal -rontrolled tubes.- Vis -U -All Products Co., though tunable without crystal. 640 Eastern Ave., S. E., Grand Selectivity 6 db dowr at 5 kc, Rapids 6, Mich. sensitivity 0.1 pv, audio output spectively. Each kit comes with 4.5 watts into self- _nntained handle and graduated -size bits VHF TV YAGI ANTENNA, (Continued on pope 106) in rollup plastic tool case. - Power Pi.e. Full gain on Vaco 317 chan- Products Co., East nels 2 13. Ontario St., Chicago, Ill. through "Hairpin" COLOR AND 110° ADAPTER for picture -tube tester, model of choice (supplied), 5 watts in- CA -.'on. Adapts company's model put to antenna. Receiver super - V-200 picture -tube tester and regenerative detector. 4 -inch reactivator for testing each gun speaker. Audio output 1 watt. of color tube, includes new Operates off 117 volts 50/60 heater voltages, 2.34, 2.68, 8.4. cycles, or with available auto YOU CAN ALSO DO THE BIG LOBS WITH WIZARDS

THE WIZARD 300' ELECTRO- MAGNETIC COUPLER FOR ALL SINGLE ANTENNA MULTIPLE -OUTLET SYSTEMS IN TV HOUSING PROJECT -2,549 IS zards In- stalled To Date: L.A. Housinç r uthority, FLAT LINE Los Angeles, California. `Pat. Pend HOME - 7 Outlets - One Antenna - No Amplification: Residence of Bob Barker, MC of the popular daytime NEC show Truth Or Consequences. $1.95 ,,- ,s LIST PRICE ,, APARTMENT - 39 Outlets -Ono Antenna 0 ;; 0 -No Amplification: The Del Rio -10236 :so< f, ft, The high electrical Old River School Road, Downey, Calif. ' efficiency of the Wizard 11,01: ! ! 300 is proven in many installations where more 61 r than thirty receivers are ff f! r1 being operated from a single antenna without rr amplification. JI (r f 1 r'!!"; 'r I! if ri' pup, r-. Information on any of the above jobs and a brochure covering APARTMENT -48 Antennas al Wizard System installations is available. Write Dept. RE89. Outlets -Two HOTEL - 120 Outlets-One Antenna-One (24 Outlets each) - No Amp ification: Amplifier: The Montecito-6650 Frank- CHARLES ENGINEERING, INC. The Paramount Riviera - 12='47 Para- lin, Hollywood, California. 6053 Melrose Avenue Los Angeles, California mount Blvd., Downey, Califer- a.

AUGUST, 1959 103

www.americanradiohistory.com Wa ^chino oscilloscope 6i 1 Wilersan test'. STAGE computer circaitry.,

Adjustirg SAGE computer operating console.

Fill Wilkerson instructs Field Eng.neers to new computer program.

104 RR.DIC-ELEC-RONICS

www.americanradiohistory.com `memory' devices. You may also be selected for additional training to learn the total functioning of a large - scale electronic data processing system."

ASSIGNMENTS ROTATED Bill Wilkerson is now a Field Engineering Group Super- visor at a SAGE site. "I help my Group Manager keep the computer in top working condition," he explains. "Together, we provide technical supervision to the Field How far can you go Engineers in our group and schedule daily maintenance checks to spot computer problems before they develop in electronics... into breakdowns. An important part of my job is to make up daily assignment sheets, carefully rotating responsibilities so that each Field Engineer moves from one com- without a degree? puter unit to another. This `cross- training' gives each man a chance to become familiar with all the parts of a Three years ago, young Air Force veteran William H. Wil- large -scale computing system and helps him add to his kerson set out to find a career in electronics, but he had no general electronics knowledge." industrial experience and no engineering degree. Today, RAPID ADVANCEMENT he has a solid electronics education, he is supervising "When I was first interviewed, I was told that IBM the maintenance of a highly advanced electronic com- promotes from within," Bill Wilkerson says. "I've found is Here's how it happened... puter, and his future bright. this to be true. In the SAGE computer program, you begin as a Units Field Engineer. Then, depending on your SOUGHT ELECTRONICS CAREER abilities, you can advance rapidly to Systems Field "I was anxious to go to college when I left the service in Engineer, Group Supervisor, Group Manager, and on up 1956," recalls Bill Wilkerson. "The Air Force had given the line. Every employee receives frequent career coun- me some fine training in electronics, enough to arouse seling to review his progress and to chart his future. In my interest and make me want to learn a lot more. An this Company, there are plenty of opportunities for the engineering education seemed to be the answer, but man who wants to grow and is willing to apply himself." family responsibilities made college impossible. Bill Wilkerson cites his career "I still wanted to work in electronics, however, so I started own as an example. Since joining IBM three looking into technician jobs. Most big companies offered years ago, he's had several' promo- tions, culminating in his present supervisory me no more than a seat at a test bench eight hours a day post. "It's a wide -open -dull, routine work that provided little or no oppor- field," he says. tunity to learn and grow. All the interesting assignments, A BRIGHT FUTURE it seemed, called for a college degree. Then I had an Although other areas for promotion are open to him, Bill interview with IBM and found just what I was looking Wilkerson would like to stay in technical management for in the SAGE Field Engineering Program." because, as he says, "Frankly, I hardly believed back in '56 that a man like myself without a college education WHAT IS SAGE? could go so far so fast, have still higher goals find SAGE is a vital part of our country's air defense. To -and such solid help in reaching them." help guard against surprise aerial attacks, SAGE parti- tions America into several defense sectors. At the heart * * * * of each sector is one of the fastest and most reliable If you have a minimum of 3 years' technical schooling - electronic computers in the world. This computer receives or equivalent experience -you may be eligible for 20 radar data from many points, checks this against known weeks' training as a computer Units Field Engineer.While air traffic in its sector, and makes it possible for Air Force training, you receive full pay plus living allowance. operators manning the computer to identify immediately all flying objects as friendly or hostile. If need be, the com- IBM is the leader in a field that offers unlimited horizons. puter can also guide a BOMARC missile to an enemy target. And, as you may already know, at IBM you receive company -paid benefits that set standards for industry today. THOROUGH COMPUTER TRAINING On joining IBM, Bill Wilkerson was given 20 weeks' WRITE TODAY TO: Mr. N. H. Heyer, Dept. 649H computer training as a Field Engineer. He learned how to Federal Systems Division maintain the various electronic units used in a SAGE IBM Corporation computing system, how the SAGE computer itself helps Kingston, N. Y. diagnose and locate problem areas, and how to make fast, precise repairs without interfering with computer opera- You'll receive a prompt reply. Personal interviews ar- tion. "It was an excellent education -both in the theoret- ranged in all areas of the United States. ical and practical aspects of electronics," he says. "Furthermore, you have plenty of opportunities to keep up with new developments in this fast-changing field. After assignment to a SAGE site, for example, you may take courses - during regular working hours -on such IBMq subjects as improved output methods or new magnetic INTERNATIONAL BUSINESS MACHINES CORPORATION

AUGUST, I 9 5 9 105

www.americanradiohistory.com ON THE MARKET (Continued trom p. 103) RADIO and ELECTRONICS TRAINING AT HOME speaker. Variable squelch. Trans- floor or table stands or hand mitter 5 watts input to final use. Response 50- 15,000 cycles, plate, transmit indicator light, choice of 25, 600 or 50,000 ohms. BUILD 16 RADIO microphone push -to -talk switch 1/2 lb.-Tandberg of America, CIRCUITS with DELUXE for receive -transmit. Supplied Inc., 8 Third Ave., Pelham, N. Y. with short -range antenna, crys- PA AMPLIFIERS, Carnival Req. U.S. tal for 1 Citizens' band channel. 1959 Progressive 5 -watt ac unit has 4- and 8 -ohm Pat. Off. Working range from 1 to 15 RADIO "EDU- KIT"' miles, depending on terrain and antenna. Extra crystals and longer -range antennas available. PRACTICAL only -Vocaline Co. of America, Inc., Old Saybrook, Conn. HOME $ 95 TAPE - HEAD DEMAGNET- IZER, model AR -2"1 S has 3 sets RADIO of interchangeable hole pieces COURSE LI outputs, microphone and phono- tuner inputs with separate gain NOW INCLUDES controls allowing mixing. Model PA 30/80 PA * 12 RECEIVERS * No Knowledge of Radio unit (shown) includes 2 microphones, 1 phono Necessary t1llaisi.***....-*-*---- * TRANSMITTER * No Additional Parts or input, 3 gain plus treble and * SIGNAL TRACER Tools needed bass controls. Five output im- * Excellent Background for TV INJECTOR pedances including constant - * SIGNAL * School Inquiries Invited 117 * Attractively Gift Packed voltage tap. Powered by * CODE OSCILLATOR to provide access to any tape volts ac or 6 or 12 volts dc.- head. Works on 117 volts ac.- Radio Shack Corp., 730 Com- Argonne Electronics Mfg. Corp., monwealth Ave., Boston 17, FREE EXTRAS 165 -11 South Road, Jamaica 33, Mass. SET OF TOOLS RADIO & ELECTRONICS TESTER ELECTRIC N. Y. SOLDERING IRON TESTER INSTRUCTION MANUAL MEMBER- ECONOMY AMPLIFIER KIT, SHIP IN RADIO -TV CLUB: CONSULTATION SERVICE HI -FI GUIDE LOUDSPEAKER models DRLA model CS -.12, stereo power am- QUIZZES TV BOOK FCC AMATEUR LICENSE TRAINING and DI?LA have response 30- plifier and preamp with con- RADIO BOOK PRINTED CIRCUITRY PLIERS -CUTTERS 16,000 cycles, handle up to 20 ALIGNMENT TOOL WRENCH SET CERTIFICATE OF MERIT trols. Ganged bass, treble. VALUABLE DISCOUNT CARD loudness. Stereo balance, reverse, mono selector. Loudness WHAT THE "EDU -KIT" OFFERS YOU switch. 12 watts rated output The "Edu -Kit" offers you a n outstanding PRACTICAL HOME RADIO COURSE at per channel. Response 20- 20,000 a rock-bottom price. Our kit is designed to train Radio & Electronics Technicians, making use of the most modern methods of home training. You will learn radio theory, construction, servicing. basic Hi -Fi and TV repairs, code, FCC amateur license requirements, You will learn how to identify radio symbols- how to read and interpret schematics, haw tomount and layout radio parts, how to w and solder, how to operate electronic equipment. how to build radios. Today it is o longer necessary to spend hundreds of dollars for a radio course. You will receive a basic education in radio, worth many times the small pricer you pay, only 522.95 complete. watts audio power. Impedance THE KIT FOR EVERYONE 8 ohms, -Utah Radio & Elec- The Progressive Radio "Edu -Kit" was specifically prepared for any person who has a desire to learn Radio. The 'Etlu -Kit" has been used successfully by young tronic Corp., 1124 E. Franklin and old ir all parts of the world, by many Radio Schools and Clubs in this country and abroad. It is sed for training and rehabilitation of Armed Forces Personnel St., Huntington, Ind. and Veterans throughout the world. The Progressive Radio "Edu -Kit" requires no nstructor. All instructions are SPEAKER LINE, models LER, included. Every step is refully explained. You cannot make a mistake. LE10, and LE30, Linear Effi- cycles. Input sensitivity 0.3 volt. PROGRESSIVE TEACHING METHOD ciency series, 8 -inch extended- -Arkay Radio Kits, Inc., 88 -06 The Progressive Radio "Edu -Kit" is the foremost educational radio kit in the world, and is n sally accepteda cepted as the standard in the field of electronics training. Van Wyck Expressway, Rich- The 'Edu -Ki t''v the modern educational principle of "Learn by Doing." Therefore, you will econstruct radio circuits, perform jobs and Conduct experiments mond Hill 18, N. Y. to illustrate the You begin by exam I loinsg the radio parts included in the "Edu- Kit." You STEREO AMPLIFIER KIT, lhen learn the function, theoryyo and wiring thnin parts. Then you build a simple heor this cyst set, you will roubl listeninglhooting en you build ut ad, model SA -3, economy unit, has learn theory, learn testing and troubleshooting.ne. Then you build more advanced radio, learn more owns theory and techniques. Gradually, in ga pro- channel and phase - reversing gressive manner, and at your o rate, you will yourself constructing io switches, 3 watts per Technics multi -tube radio c, rcuits, and doing work like a professional Radio output Technician. channel, distortion under 3 %, Included l the "Edo-Kit" course sixteen Receiver, Transmitter, Code Oscil- lator, Signal Tracer and Signal Injector circuits. These are not unprofessional response 50-20,000 cycles ±1 "breadboard" but genuine radio circuits, constructed by of range driver (shown), 10 -inch professional wiring and soldering metal chassis, plu s the n method of radio construction known as "Printed Circ uitry." These circuits operate on your regular woofer, high-frequency driver. AC or C house current. In order to provide a well-integrated and easily -learned radio course, Speakers designed for mounting the "odc nitr includes practical work as well as theory; se in from front of baffle. ,lliftigon form construction; training for all, whether your purpose isin l ingfr radio le for hobby, businessSul -adds or job; progressively-arranged material. ranging from simple bookshelf version of .11etregon circuits to well-advancedteri ro wet in Hi-Fi and Your studies will be further (aided by cQuiz materials and ouro wellwell-known -known FREE Consultation Service. folded -horn and curved- reflector THE "EDU -KIT" IS COMPLETE tweeter.- James B. Lansing You will r all parts and instructions necessary to build 16 different radio Sound, Inc., 3249 Casistas Ave., and electronics c i uits. each guaranteed to operate. Our Kits contain tubes, tube sockets, variable, electrolytic, mica. ceramic and paper dielectric condensers, resis- Los Angeles 39, Calif. tors. tie strips, coils, hardware, tubing, punched metal chassis, Instruction Man- db, ganged tone controls, ce- uals, hookup wire, solder, etc. 30 -INCH WOOFER, model ramic phono and tuner inputs. In addition, you receivee Printed Circuit materials, including Printed Circuit chassis, special tube sockets, hardware and instructions. You also receive useful set of 30W, cone of polystyrene foam 4 -, 8 -, 16 -ohm outputs. -Heath tools. a professional electric soldering iron, and a self -powered Dynamic Radio & Electronics Tester. The "Edu -Kit' also r includes Code Instructions and the Pro- moving as a true piston. Repro- Co., Benton Harbor, Mich. gressive Code Oscillator, in addition to the F.C.C. -type Questions and Answers for Radio Amateur License training. You will also receive lessons for servicinga with STEREO FM -AM TUNER, the Progressive Signal Tracer and the Progressive Signal Injector, and a High Fidelity Guide and Quiz Book. Everything is yours to keep. model 580, two independent J. Statatis, of 25 Poplar Pl., Waterbury, Conn., writes: "I have repaired several tuners. Both oscillators tempera- sets for my friends. and made money. The "Edu -Kit" paid for itself. I was ready to spend $240 for a Course, but I found your ad and sent for your Kit." ture- compensated, 1 -mc wide - band FM detector, FM sensi- UNCONDITIONAL MONEY -BACK GUARANTEE tivity 1.5 µv, AM rf stage, 10 -kc The Progressive Radio "Etlu -Kit" has been sold to many thousands of individuals, schools and organizations, public and private, throughout the world. It is recognized internationally as the ideal radio course. BY Popular demandhnd theProgressive Radio Edu-Kit" is now available in Sp a is P a duces frequencies to below 18 It is understood and agreed that should the Progressive Radio "Etlu -Kit" be returned to Progressive "Etlu -Kits" Inc., for any reason whatever, the pur- cycles. Frame is one -piece cast- chase trice will be refunded in full. without quibble or question, and without delay. ing. Cone diameter 30 inches. The high recognition which Progressive "Edu- Kits" Inc., has earned through Cabinet 54 inches high, 32 wide. its many years of service to the publie is due to its unconditional insistence upon the maintenance of perfect engineering, the highest instructional stand- -Electro -Voice Inc., Buchanan, ards, and 100% adherence to its Unconditional Money -Back Guarantee. As a result, we do not have a single dissatisfied customer throughout the entire Mich. world. DYNAMIC MICROPHONE whistle filter, AM sensitivity 3 Grampian model D1'4, slim -line ORDER FROM AD- RECEIVE FREE BONUS RESISTOR AND Av. -Pilot Radio Corp., 37 -50 36 CONDENSER KITS WORTH $7.00 design supplied in desk holder, St., Long Island City 1, N. Y. readily removed for use with Send "Edu -Kit" Postpaid. 1 enclose full payment of $22.9S. STEREO KITS. Model SA -40 Send "Edu -Kit" C.O.D. I will pay $22.95 plus postage. Send we FREE additional information describing "Edu- Kit." complete amplifier 20 watts per Name channel. Bass, treble, balance, loudness controls. Rumble, input, Address mode, loudness, speaker -selector switches. Tape -head input and 1186 BH Dept. 155G choice of 2 tape equalization Progressive "EDU- KITS" Inc. wleay, N. 1 curves. Model ST -45 stereo FM-

106 RADIO- ELECTRONICS

www.americanradiohistory.com ON THE MARKET (Continued)

TRIDGE, Professional 55. High - compliance version of model CD (for changer use) is intended for transcription arms. Track- ing force 1.5 grams, diamond stylus 0.5 -mil radius, output 0.4 volt at 5 cm /sec. Channel AM tuner matches SA -40 stereo separation 20 db, response 20- amplifier. Also available as fac- 15,000 cycles ±3 db. Supplied tory -wired units. -PACO Elec- with 2 miniaturized plug -in net- tronics Co., Inc., 70 -31 84th St., works to equalize output for for varions physical mountings Glendale 27, N. Y. low- and high -level phono in- in changer arms. Output 2 volts, puts. -CBS Electronics, Dan- response 50- 10,000 cycles, sepa- STEREO AMPLIFIER -PRE- ration 20 db, stylus pressure 10 vers, Mass. in 3 Consumes 15 watts AMP, model 240. 15 watts per grams. - Astatic Corp., Con- ranges. channel, tone controls operable STEREO MAGNETIC CAR- neaut, Ohio. at 117 volts ac.- Hickok Elec- locked together or adjustable TRIDGES, series VR -22. Similar trical Instrument Co., 10514 in appearance to G -E Golden Dupont Ave., Cleveland 8, Ohio. Classics. VR -225 has 0.5 -mil STEREO BALANCE METER stylus for transcription arms; model Stereo- Monitor. Inserts at output of stereo amplifiers, AC AMMETER measures cur- VR -227, 0.7 -mil diamond for rent drawn by radios, TV sets, changers. VR -225 response 20- reads balance or imbalance of 20,000 cycles ±3 db, channel separation up to 30 db, lateral for each channel separately, speaker- selector switch, 2 phono inputs and switch positions labeled for changer and turntable separately, tape head input, automatic shutoff controlled by changer, loudness control and switch, hum and noise down 80 stereo signals. Rack or panel other appliances. Model 307 has db. -Pilot Radio Corp., 37 -50 36 mounting or in various wood St., Long Island City 1, N. Y. 5 ranges from 1 to 25 amps. cases. -Park Products Co., Inc., Built -in transformer. Using STEREO PHONO CAR- compliance 4 X 10' cm /dyne, 4901 Perkins Ave., Cleveland 3, model 10 clamp -on, ammeter vertical 2.5 X 10-e, tracking Ohio. ranges are extended to 300 force 2 to 4 grams. -General amps. Black molded case ap- Electric Co., West Genesee St., VTVM- TUBE - TRANSISTOR proximately 3 x 4 x 11/4 inches. Auburn, N. Y. TESTER, model 820. Tube Caddy -Triplett Electrical Instrument HIGH - OUTPUT STEREO Pal tests transistors, picture Co., Bluffton, Ohio. END phono cartridge line. 3 models, and receiving tubes. Is also a 70TS, 74TS, 76TS -TB. Replace- 10- megohm input vtvm. 4 dc All specifications on these pages are ment, original- equipment and voltage ranges 1.5 to 750. Meas- from manufacturers' data. mono -to- stereo conversion units ures resistance to 100 megohms

Yes, you get this big, brand new book, "150 Radio- Television Picture Patterns and Dia- grams Explained ", absolutely FREE! Complete NOW! 11x22" Schematic Diagrams on leading models Radio and TV Sets help cut your servicing BIG time. Easy -to -read, large 81/2x11" pages, with full instructions on how to use the diagrams. A "must" in every 7 BOOKS repair kit. You get this book as a FREE Gift for asking to IN ONE see Coyne's new 7 -book set, "Applied Practical Radio - Television"! GREAT SET! At Last! Money- Making "Know -How" On Transistors, Color TV and Servicing Dyne s great 7- volume set gives you all the Just mail coupon for 7- volume set on 7 days free trial. answers to servicing problems -quickly! For SEND NO MONEY] basic We'll include book of 150 TV -Radio Patterns & Diagrams. If you keep the "know -how" that's easy to understand 5 Years set, pay $3 in 7 days and $3 per month until $27.25 plus postage is paid. you'll find everything you want in Volumes 1 to Of Valuable (Cash price, only $24.95). Or you can return the library at our expense in 5 on over 5000 practical facts and data. Every step Supplements 7 days and owe nothing. YOU BE THE JUDGE. Either way, the book of from fundamentals to installing. servicing TV -Radio Patterns is yours FREE to keep! Offer is limited. Act NOW! and troubleshooting all types of radio and TV sets. So up -to -date it includes the latest on COLOR TV and UHF. All this plus Volume 7- CF-i TRANSISTOR CIRCUITS-the most complete FREE TRIAL book ever published on the applications of tran- BOOK -FREE COUPON! sistors in electronics. New! Set has colorful de- With your set you also sign, washable covers. net Coyne's annual Sup- Educational Book Publishing Division plement Service FREE COYNE ELECTRICAL SCHOOL, Dept. 89 -T1 for 5 years. Keeps your EXTRA! $6$-Page TV Cyclopedia Included! set up -to -date on every- 1501 W. Congress Pkwy., Chicago 7, III. you thing that will be new YES! Send 7- Volume "Applied Practical Radio -Television" for 7 days FREE TRIAL Coyne CYCLOPEDIA. Answers problems on servicing. in radio, television, per your offer. Include TV -Radio l'alterna & Diagram Book FREE. alignment, installation, etc. in easy ABC order. Use electronics and elec- this 7- volume TV-RADIO LIBRA1tY FREE for 7 days; tricity. Name Age ._ get the Servicing Book FREE! Address City Zone State Where Employed Check here if you want library sent C.O.D. You pay postman $24.95 plus C.O.D. postage on delivery. 7 -day money -back guarantee.

AUGUST, 1959 107

www.americanradiohistory.com OPPORTUNITY ADLETS Rates -50c per word !including name, address and initials). Minimum ad 10 words. Cash must accom- pany all ads except those placed by accredited agen- TRÍ cies. Discount, 10% for 12 consecutive issues. Mis- leading or objectionable ails not accepted. Copy for October issue must reach us before August 15, 1959 RADIO -ELECTRONICS, THIS 154 West 14 St., New York 11, N. Y.

CASH PAID! Sell your surplus electronic tubes. Wan unused, clean transmitting, special purpose, receiving, TV types. magnetrons, klystrons, broadcast, etc. Also ONE want military & commercial lab test and communication gear. %Ve swap too, for tubes or choice equipment. Send specific details in first letter. For a fair deal write, wir or telephone: BARRY, 512 Broadway, New York 12 . N.Y. WAlker 5 -7000. INDUCTORS for Crossover Networks. 118 types in stock. Send for brochure. C & M COILS, 3016 Volute., Avenue N. W., Huntsville, Ala. HI -FI, Recorders, Tapes. FREE Wholesale Catalogue. CARSTON, 125 -T East 88th St., New York 28, N. Y. EXAMINING PHONO NEEDLES STEREO TAPE RENTALS. For the very best at lowest prices. \ \'rite CALIFORNIA TAPED MUSIC ASSN., If you want to examine the point of 763 El Camino Real, Redwood City, Calif. a phonograph needle and don't have a DISCOUNTS UP TO 50% on Hi -Fi amplifiers, timers, needle- inspection microscope, you can speakers, tape recorders, individual quotations only. no catalogs. CLASSIFIED HI -FI EXCHANGE, 2375 East use the viewfinder on a small folding 65th Street, Brooklyn 34, N.Y. camera. Just hold the needle close to FOR THE ULTIMATE THRILL in stereo sounds, write for the l'ai /Tape stereo tapes titled 1St. Francis Whi- the small lens in the front of the finder pens) .Anthentie sounds of San Francisco. What & Where) Part; guessing gante. Ghost Trains) Steam trains and look in at the top. You will find recorded all over historic Calif. Mustard & Sand( A day at Santa Cntz famous board walk. Omnibus) Cal /Tape that the viewfinder makes a powerful demonstrator. Relaxation) Mood music. played by Jose magnifying glass for examining tips Gullies on the Hammond Organ at World Famous Itiek- eys Studio Inn, Palo Alto, Calif. All recording are of recording and playback needles. 2 Channel 71/2 ips. Prices are from $7.5., to $9.05. Dis- tributor inquiries teeleaste. ('ALIFO1tNIA TAPED When using the viewfinder on the 511'S1C ASSN., 1971 Cordilleras Road, Redwood City, larger folding cameras, it may be nec- Calif. 10 NEW TUBES for your TV $14.95. Send list of Hates essary to unscrew the front lens and or make and model of set, except picture tubes. 5 New needle tubes for your radio $5.95. All fully guaranteed and not hold it in your hand to bring the mechanical or electrical rejects. CRYSTAL ELEC- into focus. This is not necessary with TRONICS, 9507 -101 Ave., Ozone ('ark, N. Y. III. vest -pocket models. In either case, shine 1-11700. LABORATORY QUALITY equipment and Military Sur- a strong light on the needle tip while plus Electronics bought, sold. ENGINEERING ASSO- examining it.- Arthur Trauffer CIATES, 434 Patterson Road, Dayton 9, Ohio. ALL MAKES OF ELECTRICAL INSTRUMENTS AND TESTING equipment repaired. ILAZELTON INSTRU- BOWL -COVER SERVICE AID MENT Co., 128 Liberty Street, New York. N.Y. WHAT YOU KNOW plus spare time ought not be My toolkit for house calls contains, wasted.Let us show you hot. Order your copy of Invent- ing The Invention today. $4.95 post paid. EATON among other things, several sizes of ROLLER & MANI'F.ACTUItING COMPANY, 300 North plastic bowl covers. They come in Meridian, Eaton, Indiana. as bags for holding FREE WRITERS CATALOGUE giving manuscript mighty handy markets. Write LITERARY AGENT !HEAD, 915 Broad- screws, knobs and other hardware re- way, New York 10, N. Y. DIAGRAMS FOR REI'AIItING RADIOS $1. Television risky? $2. Give make, Model. DIAGRAM SEIIVlt'E, Box 672 -ItI, Hartford 1, Conn. SPECIAL OFFER, Complete correspondence course in Electronics, Television and Radio only $40.50. :01 new modern material. Formerly sold for $400. 43 tests over 20011 pages. Limited number available. Write dept. RE. ELEC'TRONIC'S TRAINING, P.O. Box 704, Pittsburgh 311. l'a. Not for the lion. And the wrong P.A. 5 INCH T.V. Test CRT. Complete w /adapter $3.95 post- speaker can swallow your profits just paid. CRYSTAL ELECTRONICS, 9507 -1111 Ave., Ozone Park, N.Y. Ili 1 -07110. as fast. But you take no risks with CAMERA Repairmen greatly needed! You can learn manufacturers' service methods at hone, in your spare University, because you can choose time! Free, big illustrated book tells how! Write today. NATIONAL CAMERA REPAIR SCHOOL, Dept. 11E -0, the one right speaker for the job. The Englewood, Colorado. CALCULUS, Powerful Modern Mathematics, Easy Prac- world's most comprehensive lion of tical Lessons, First Four $1. DLATHCO, 4256 -4 Minotor, Cincinnati 17, Ohio. P.A. speakers is described in Univer- moved from a set, as well as being OFFSET PRINTING-1,000 01211 $5.50. 511/$17. Color sity's new product catalog. It's FREE. handy slip -on protective covers for or white. Fast! 5,000 colored circulars $39. Complete: guarding against accidental speaker- Art, copy, layout, printing. PROMOTION -Its, 385 Also, invest $1 in the all -new 64 -page Broadway, New York 13, N. Y. cone punctures when transporting a REMOVE "C" Washers, inside outside retaining rings University Technilog, the authorita- with fine tool $1.95 postpaid. STILLWELL'S, 5242 East chassis to the shop for repair. I find 32nd Street, Tucson, Ariz. tive reference book for planning P.A. them very useful and would like to pass NEW 1959 AUTOMOBILES -to 25% off retail prices. to fellow tech- Delivered anywhere. MEDER, 550 -RE Fifth Avenue, speaker installations. See your local this helpful hint along New York 36, N. Y. nicians encountering such service prob- distributor, or write Desk J -4, SONGPOEMS and LYRICS WANTED! Mail to: TIN lems.-J. A. Conrad PAN ALLEY, INC. 1650 Broadway, New York 19, N. Y. University Loudspeakers, Inc., 80 So. RADIO & TV TUIIES at Manufacturers Prices! 100' /e AC -DC TUBE SAVER Guaranteed! Brand New! No re- brands or pulls! Kensico Avenue, White Plains, N. Y. UNITED RADIO, Box 1000, Newark, N.J. To reduce the possibility of burnt - IF YOU IIAVE a background in Electronics, but are out tube heaters in series -string equip- having trouble passing FCC ('hone Exams, my 12 years experience as chief instructor of Electronics School can ment, try increasing the value of the help you over the hump. Not a course. Write me personally for Free information. WALLACE COOK, 1614.1 Mor- series resistor by about 10c/0. This re- sr n Road, Jackson I. Miss. duces the surge through the cold heaters that does the damage when the set is turned on. -N. Schvedman TAPE RECORDERS 45 -RPM CHANGER HI -FI COMPONENTS SLEEP LEARN KITS If you have a 45 -rpm record changer THE WORLD'S MOST COMPLETE LINE MERITAPE UNUSUAL and are having trouble with noise, Low cost, high VALUES RADIAL HIGH FIDELITY WEATHERPROOF PAGING quality recording FREE 1959 CATALOG WIDE -ANGLE SUPER -POWER SUBMERGENCE -PROOF needle -talk, distortion or scratch, there tape, in boxes or cans. DIRECTIONAL EXPLOSIONPROOF TALK -BACK may be an easy solution. Tape a nickel DRESSNER, 69 -02RE 174 St., Flushing 65, N.Y. 108 RADIO -ELECTRONICS

www.americanradiohistory.com TRY THIS ONE (Continued) to the rear end of the pickup arm. In this way, you reduce stylus pressure. After all, noise and scratch are in the TELEVISION bottom of the groove and the music is Never before in American history has the in the sides. Reducing the pressure also need been so great for Trained Enginreers lengthens the life of the stylus and your and Technicians. No other type of trairring records. -Lee Maggs can compare with actual shop practice you get at Healds under expert instructors. CLAMP SAVES PLUG Bachelor of Science Degree 27 Months Ever accidentally step on a phone Radio -TV Technician including Color TV (12 Months) plug and feel its bakelite handle crush Electronics Technician (12 Months) Industrial Electronics Technician (12 Months) under your weight? Why let a costly Electronics Engineering (B.S.. Degree) Electrical Engineering (B.S. Degree) Mechanical Engineering (B.S. Degree) Civil Engineering (B.S. Degree) AT HEALDS YOU LEARN Architecture (B.S. Degree) ranks FIRST West of the BY DOING IN MODERN Heald College Mississippi in "Who's Who in America" ELECTRONICS Approved for Veterans DAY AND EVENING CLASSES LABORATORIES Write for Catalog and Registration Applieafilea. New Term Starting Soon. HEALD Your Name accident such as this happen when you ENGINEERING COLLEGE Address can by a Established 1863 easily prevent it slipping City large paper clamp over the plug? Other Van Ness at Post, RE types of electrical connectors can be San Francisco, Calif. State protected like this, too. -Scott Mack HANDY FILE Often at the bench or in the field you r want to dress up a soldering job but don't have a file handy. Also solder file lose SAVE will clog a and make it its all effectiveness. An excellent, cheap sub- Check stitute for a metal file is an emery CAPACITORS hoard. They are available in packs of ELECTROLYTIC 10, for a penny apiece, at any drug TIME in Seconds!

or variety store. Try using one next Merely select the electrolytic and saahsi itote it. time you have a mike or phone plug you 10 big eleenrolytics from 4 to 350 Mfd. -o safety want to dress up after soldering. with substitute in any circuit from 2 to 450 volts. - Model ES -102 ,,,COMPLETELY SAFE -no arc or spark con - 1. Burton Burnett END venting or disconnecting. oNLr SE E . AUTOMATIC CAPACITOR DISCHARGE- within DEALER NFT seconds afterI releasingl test switch by unique Lass'-rren .nu cai for the surge protector circuit 50 pccar5 ßg0 ® inc oival-i mots See other SENCORE Ca ry it anywhere- measures only ... NO CAPACITOR HEALING -surge pmterror circuit prevents occidental healing of cmacr being In Gernsback Publications ads in this issue. IN" II a e34" W a TN" 0 "bridged" in wkrt. inSERVICE INSTRUMENTS CORP. 121 Ofuirlat Rd. Addison, III. At LeadingLeafding Parts Distributors. J HUGO GERNSBACK, Founder Modern Electrics 1908 , Wireless Association of 1908 Electrical Experimenter 1913 Radio News 1919 HELP WANTED ?- You'll get what you want if you Science & Invention 1920 Television 1927 Radio -Craft 1929 advertise in RADIO- ELECTRONICS OPPORTUNITY AD- Short -Wave Craft 1930 Television News 1931 LETS. Rates as low as $5. Write RADIO -ELECTRONICS, Some larger libraries still have coptes of Modern Electrics 154 14th Street, New York 11, N. Y. on file for interested readers. West In August, 1909, Modern Electrics

The Nauen Wireless Plant. ALL NEW, fully d.usl -aced catalog of How to Make a Polarized Relay, by professional helps it vented by servicemen for servicemen :orioles: H. W. Secor. Fono -Magic to °Lap slipping turn- Musical Wireless Receiver. tables R-COLUMBIA'S Metal Strobe for 10t ó accuracy in A New Type of Wireless Transformer, turntable tuning by A. Press. Kleentrol in spray on or easy control cleaning Wireless Dirigible Torpedo. Magna Lite free bctn hands while New Telefunken System, by The Berlin lighting dark corners, Correspondent. E -Z Ply speaker carre crment Nu -Shaft for radio cbck knob shalt Airship Run by Wireless. free replacement Method Testing Switchmatic wall rmeplacle NOW of Short Circuited gives any number of TV outlets from lot Condensers, by I. Wolff. SHORTCUTS single antenna Humi -Kup for weatherproot 2-set A D. C. SERVICE Novel Detector, by Spooner. antenna coupling Detector Construction, by L. Spangen- PROFITS PAGE Kleentrol Tape to clean recorder 16 heads without disrlurntrmg berg. Miracle Lube handy oil for many New French Wireless Apparatus, by H service problems PROD CO-. INC Trolmasler clearing- lubricating tool A. C. Marlowe. R-COLUMBIA nionw000. ionxois for application of Kleersml Solvent Construction of a Relay for Converting Cubes Mortar-ate outlet hunting 50 aD,laiN Cheater Wwr,eruaa Srnel MIS Loop Antenna to Straightaway, by En iW0 SERVICEMAN'S Write for your FWE E copy today. A. C. Austin, Jr. R-Columbia Prod. Co., Inc. A Variable Condenser, by L. W. Teller. 305 Waukegan Ave., A Conductive Wireless System, by E. E. CATALOG Highwao.u, III. Gourley. ASK FOR CATALOG No. 59 AUGUST, 1959 109

www.americanradiohistory.com f., - \\\ IRCUITS °'...*... \ )\ 1

HORIZONTAL OSCILLATOR TESTER This simple instrument checks for A minimum reading, obtained by rotat- proper frequency and intermittent hori- ing R1, usually falls around the center zontal oscillators in TV sets. The unit of the pot's range. This position is is an in-circuit tester. An octal test - marked and compared to future read- socket adapter for the horizontal output ings to detect faulty low- output oscilla- tube, tapped at the grid, is used for tion. .005 The other half of the 6AL7 acts as a

T I © frequency indicator. Transformer Tl's o b CI 30T c' ó 251,1,f secondary and capacitor Cl form a ±---® wavemeter that gives six resonant TV CHASSIS - 6A L7 6SQ7 TWIN -INDICATOR 270K 6J5 TEST SOCKET ADAPTER (OCTAL) 6 .05 47K 3 .03 100K RI PHONES GRID I MEG you may now select TUBE PIN LINEAR 6866 5 INDICATOR 6806 5 from two magnificent 6AU5 68D5 6C D6 5 6D06 5 700VCT 6X5 20011 ON-OFF 8 I + ++ Fo 50 K H I F I P H O N O CARTRIDGES 300V 117 VAC T T Shure High Fidelity Stereo Dynetic phono Y20 20 /450V cartridges are designed to satisfy the most 6.3VT06X5HTR 450V - critical requirements. Made under custom laboratory conditions, each unit is checked 6.3VTO electrically, mechanically and accoustically HTRS HORIZ OSC COIL WITH 30T N° 28 ENAM WIRE PRIMARY to insure trouble -free performance. WOUND OVER EXISTING COIL horizontal frequency takeoff. Leads peaks which are recorded on Cl's dial. PROFESSIONAL should be no more than 5 feet long, and If the frequency of a set is off, the MODEL M3D coax or shielded cable should not be peaks fall at different points. AT $45.00 used. The 6SQ7 rectifies and amplifies The 6J5 is a horizontal amplifier and the horizontal frequency, giving a mini- provides for audio detection of the hori- *audiophile net, mum reading on one side of the 6AL7. zontal frequency. Lieberman with 0.7 mil diamond Morris

Incomparable quality -the overwhelming choice STAIRCASE GENERATOR of independent critics and experts. Floats at Staircase waveforms are used exten- means. The control current, however, only 3 grams in transcription tone arms. Distor- tion -free response from 20 to 15,000 cps. sively, for example, when testing tran- must be a staircase waveform with Superbly designed and built to perfectionist sistors. The complete family of char- perfectly horizontal and equally spaced tolerances. acteristic curves of a transistor can steps. Fig. 1, which appeared in Radio be displayed on a cathode -ray tube with and Fernsehen, shows a staircase gen- CUSTOM the input voltage in abcissas, the input erator. It uses two limiter tubes con- MODEL M7D current in ordinates and the control trolled by sinusoidal 60 -cycle signals AT $24.00* current as a parameter. with a 45° phase difference. The out- The feed voltage is a sawtooth wave- puts of the four sections are four audiophile net, with 0.7 mil diamond form, easily produced by conventional rectangular waves. By adjusting the

EMITTER Outclasses every cartridge except the Shure actual listening NEG STAIRCASE M3D -by tests! Tracks per- 250 K fectly at minimum pressure available in record BASE changer arms. Smooth from 40 to 15,000 cps. VI-a V2-E

STEPMA lMA Y200V

EG Use Only Shure Replacement Styli... I 100V Inferior imitations can seriously degrade the performance of the cartridge. EMI ER POS STAIRCASE .05 AC INPUT BA Literature available: Department 12 -G 200 SHURE BROTHERS, INC. 222 Hartrey Avenue, Evanston, Illinois Fig. 1 110 RADIO- ELECTRONICS

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DISC CERAMICS 1,4-L 1:cmhers, 51 COMPLETE KIT 20 - TUBULAR CONDENSERS Iv 51 TUBULAR CONDENSERS -60ov with SET 10 - ..4' $1 of WESTINGHOUSE TUBES 50 - ASSORTED FUSES l,,r - $1 100 - ASST. I/u WATT RESISTORS - on see,: $1 GI's, , ilsN7, W D 4- 61'BO, /l''. nil. 121;117, 61(06, 6W.), 6K6, Dimensions 171/2" x 16" 70 ASSORTED 1 WATT RESISTORS.o,oe 5', S1 Shipping weight 40 lbs. 1X211, 5174, fil ;Ni. CI IC, isin the Tuner (less CRT) - $7997 35 - ASSORTED 2 WATT RESISTOR$.ome 5', 51 50 ASST. TUBULAR CONDENSERS... SI Also sold on EASY- PAYMENT -PLAN Buy LIFE -SIZE Instructions- 92,49 -and buy Parts as you build. - 10 - 6' ELECTRIC LINE CORDS with plugs 51 J 5 - TV CHEATER CORDS .,'n 1. et plugs Si 4 - 50' SPOOLS HOOK -UP WIRE 4 colors 50 - STRIPS ASST. SPAGHETTI .,ea eizes 51 100 - ASST. RUBBER GROMMETS best sines S1 BUILD ww CABINET ANY TV CHASSIS 100' - TWIN LEADIN WIRE 300'.1! heavy duty $1 Comparable to the type that Top Mfrs. use on high priced TV sets. 50' - FLAT 4- CONDUCT. WIRE 1=11n, purposes $1 25'- INSULATED SHIELDED WIRE. Si CABINET KIT with done, 90% of the job includes - 32' - TEST PROD WIRE 1, 1,1.o Ir.,t or black).. ,51 FRONT SECTION in Solid Mahogany, Walnut or Blond Ko- 1 - 57 INDOOR TV ANTENNA 1,i ., uo . Si 20 ASST. TV KNOBS, Etc. S1 rina. TOP, SIDES, BACK, MASK, SAFETY GLASS, ETC. - ESCUTCHEONS, 3 - ASST. TOGGLE SWITCHES -1 -t dpdt. And EASY -TO- FOLLOW ASSEMBLY INSTRUCTIONS 6 - ASST. SLIDE SWITCHES sgsi dpdt, etc. S1 Front. Top and Sides .supplied ill a beautiful Piano Finish Knob panel 4 - BAKELITE KNIFE SWITCHES Indt 51 undrilled For matching flask specify type or number of ('IRT used. 100' - FINEST NYLON DIAL CORD best size $1 Sante price-Mahogany, Walnut or Blond. IShipping weight 36 lbs.) 200 - SELF TAPPING SCREWS _K x y " Si 35 - ASST. RADIO KNOBS and push -ml $1 100 - KNOB SPRINGS "M. l:,r'I silo 'S" x 1/2" S1 21" CABINET KIT 26 H. 25 W, .16" 100 - ASSORTED KNOB SETSCREWS Si 25 - ASSORTED CLOCK RADIO KNOBS $1 24" or 27" TV Cabinet Kit 24' or 17" TV Cabinet Kit ..$24.95 .. $36.47 27" Front Panel Assembly .. $22.97 600 - ASST. H'DWARE .,,, "<. m.:. ;eels, ,t, 51 1.:a. 35 - ASST. SOCKETS , uoc:,I a iotot, Si 20 - ASSORTED TUBE SHIELDS . 51 TV CONVERSION KIT :dl Essential Parts. .515.98 90° 52950 50 - ASST. MICA CONDENSERS e in s'' $1 , KIT :,Il s: -wo S I'.1. . 13.97 IMPORTED PORTABLE RADIO 70° TV CONVERSION 50 - ASST. CERAMIC CONDENSERS " 51 . h' 'i v1 uct . 4.59 AGC KIT 1,1d'. ASST. VOLUME CONTROLS slvlteh $1 FLYBACK TRANSFORMER 5.74 We slue Scooped the 10 - UNIVERSAL 110° market on this beauty 5 ASST. VOLUME CONTROLS o _ switch $1 r1:,ß Ia1,- s 1.79 - 17" TV MASK r GENUINE 100- VOLUME CONTROL HEX WITS Si 21" TV MASK lam- x __ T 2.74 ,sass LEATHER 20 - ASST. PILOT LIGHTS pohm_r l'pex Si 21" TV SAFETY GLASS i- - 5,16 4 -TUBE SUPER" 10 - PILOT LIGHT SKTS. 1 =l ones tyre. wired 51 24" or 27" TV MASK cr:1s _1''..,," 5.47 HET 50 - ASST. TERMINAL STRIPS t. - s, 4 lug 51 TV SAFETY GLASS s -- - 5.87 PM SPEAKER 24" or 27" -)" 10 - ASST. RADIO ELECTRO. COWDENSERS 51 CHANGER 4-- 1.,.1 < -L s w,',1. (autriice 26.94 r5 ant VM BUILT -IN AN. 5 ASST. TV ELECTROLYTIC CONDENSERS 51 -Sad ion! Stereo Ca Iridge 49.77 - RC -88 GARRARD CHGR 4 TENNA 25 ASST. MICA TRIMMER CCNDENSERS S1 STEREO CART 4.62 - RONETTE or SONOTONE QUALITY TONE 2 ELECTROLYTIC COND. 1,1 a, 1-,1'v 51 SPEAKER 9770m Twin -Cone 6.94 - 8" NORELCO HI -FI Yours 30 FP CONDENSER MOUNTING WAFERS 51 UNIVERSAL TWIN -CONE SPKR.s.° n,as 6.94 ít797 - 12" for only 3 ELECTROLYTIC CONDENSERS So 45e $1 rod 12AT6.50B5,35W1 5.98 - AC -DC PHONO AMPLIFIER 71 z" x 41 x 21, -a" Weight 21a lbs ." :,I.I50V, $1 Literature on CONVERSION 6 AOC KITS -Free request. 3 - ELECTROLYTIC COND. Stereo Cartridges we supply, play all (monaural n & stereo) Also sold with Batteries - Complete ready -to -play S9.59 10 - HV TUBULAR CONDENSER'' 007-1600v $1 Records. 10 - HV TUBULAR CONDENSERS ,11 -0000v 51 10 - HV TUBULAR CONDENSERS .5.3000v 51 TUBULAR CONDENSERS-85 °C TOP QUALITY- Equally as good for Radio or TV work 35 - MICA COND. 20 -$mmf & 15 -21 mmf $1 35 - MICA COND. 20 -50 mmf & 15 -68 mmf $1 .01 -600v, .02 -600v, .03 -600v 50 ea. .0047 -400v, .01-400v, .02.400v, .047-400v, .001 -600v, .0047 -600v, 35 - MICA COND. 20-100 mmf & "5-370 mmf $1 .1-400v, .25-400v, .47 -400v, .047 -600v, .1-600v, .25 -600v, .001-1000v, .0047- 1000v, .01- 1000v.8c ea. 35 - MICA COND. 20 -470 mmf & 5-680 mmf Si .035- 1000v, .047- 1000v, .1- 1000v. .007- 1600v, .03-1600v, .05-1600v, .005- 3000v..001.6000v, 140 ea. 35 - MICA COND. 20 -Q20 mmf & 15 -1000 mmf 51 35 - MICA COND. 20 -2200 mmf & "5-1 100 mmf S1 35 - MICA COND. 20 -3300 mmf & 'i.5 - 1700 min'. 51 5 8- ea. ELECTROLYTIC CONDENSERS -85 °C 1 -50v, 1 -150v, 2 -450v, -150v, 150v,..19í 35 - MICA COND. 20 -6800 mmf & "5 -10000 mmf 51 20/20 -150v, 50/30 -150v, 40 -150v, 10 -450v, 20 -450v, 30 -450v, 40-450v, 60 -450v. 80 -450v 340 ea. 35 - CERAMIC COND. 20 -5 mmf & 15 -10 mmf 51 35 - CERAMIC COND. 20 -25 mint & 15 -47 mmf S1 factory stock in Stackpole, I.R.C., Speer, etc 35 - CERAMIC COND. 20 -56 mmf & 15 -82 mmf 51 CARBON RESISTORS -Regular 35 - CERAMIC COND. 20 -100 mrnf I5 -150 mmf 51 mmf 15 mmf t/2 WATT 10% 10, 39, 47, 100, 120, 150, 270, 330, 390, 470, 560, 680, 820, 1k, 1800e 20 ea. 35 - CERAMIC COND. 20 -270 1 -470 51 35 - CERAMIC COND. 20- I000mmf.115- I500mmf 51 1/z WATT 10% 2700, 3300, 3900, 4700, 5600, 6800, 8200, 10k, 15k, 18k, 22k, 27k, 33ke 2c ea. 35 - CERAMIC COND. 7n- 29'0.. f'. IS -5010 mm` 51 120k, 150k, 180k, 220k, 270k, 330ke 2c ea. 1/2 WATT 10% 39k, 47k, 50k, 56k, 68k, 82k, 100k, 50 - 100Kí' 1/2 WATT RESISTORS 5% Si 2c ea. 2 WATT 10% 390k, 470k, 560k, 680k, 820k," 1, 1.2, 1.5, 2.2, 6.8, 10, 15 MEGA? 50 - 470Kí? 1/2 WATT RESISTORS 10% 51 3e ea. 10 ASST. WIREW'ND RES. 5. 10, 20 watt 51 1 WATT 10% 3.3, 10, 39, 100, 120, 150, 330, 470, 560, 680, 820, 1k, 1800, 2700, 4700e - TRANS. 5í1L6 typo $1 30 ea. 3 - AUDIO OUTPUT 1 22k, 27k, 33k, 39k, 47k, 68k, 82k, 100k, 150k, 470k, 680kß? WATT 10% 6800. 10k, 15k, 18k, 3 - AUDIO OUTPUT TRANS. ,n.6 ,r eve type. ,51

100k, 470ke? 40 ea. , 2 WATT 10% 18, 22, 82, 100, 180, 2200. 3900, 4700, 6800, 8200, 18k, 22k, 3 - I.F. COIL TRANSFORMERS s "e kr 51 3 - I.F. COIL TRANSFORMERS -0.7 mc. FM, 51 4 - OVAL LOOP ANTENNAS :, hl -gam type Si I U D 5 -5w, 16 -10w, 20 -10w, 47 -5w, 100 -5w, 140 -5w, 220- 5w 16í ea. W R EWO N RESISTORS 3 - LOOPSTICK ANT. o m, ris :rt,lustabte $1 280 -10w, 390-5w, 470 -5w, 500 -10w, 680-10w, 820 -5w, 1K -5w, 1K -10w, 1500-5w, 2K- 10w 16t ea. 12 - RADIO OSCILLATOR COILS 456 kg SI 2500 -5w, 3K -10w, 4700-5w. 5K -10w, 6K -10w, 7K -10w, 8200 -5w, 10K -5w, 15K -5w, 22.5K12w 16e ea. 3 - 1/2 MEG VOLUME CONTROLS with switch $1 5 - 50K VOLUME CONTROLS - s. Hrh S1 CERAMIC CONDENSERS 1, 2, 3, 5, 6, 10, 22, 25, 47, 50, 51, 56, 82, 100, 120, 150 uuut .... 30 ea. 10 -SURE GRIP ALLIGATOR CUPS. 51 CERAMIC CONDENSERS 220, 250, 270, 330, 470, 1k, 1200, 1500, 2k, 5k. 6800, 10k ,nmf,... 3c eo. 1 -GOLD GRILLE CLOTH] t. a ort2 "x1S " 51 5 SETS SPEAKER PLUGS i1, a $1 MICA CONDENSERS 5, 25, 50, 60, 68, 75, 100, 120, 150, 220, 270, 330, 470, 510 clot ,... 30 ea. - 10 - SETS PHONO PLUGS and PIN JACKS $1 1111111 30 ea. MICA CONDENSERS 560, 680, 820, 1k, 1500, 2k, 2500, 3300, 4700, 6k, 6800, 8k, 10k .. 2 - 52.50 SAPPHIRE NEEDLES 5 DIODE CRYSTALS 2-1N21 - N22 1- tN,i4.$1 OF $10 OR OVER ON $1 BUYS - More "DOLLAR Buys " -Deduct 10% ON ORDER 3 - DIODE CRYSTALS 1- lw;,l. - - N64, 1-IN 69.$1 1 - 5" PM SPEAKER :anleo 4,-5 magnet $1 20 - RCA TUBES .37 $1 2 - SELENIUM RECTIFIERS 1 E4 - 4" PM SPEAKER alnico as magnet $1 4 - RCA TUBES 1 U4 also secs'.:,.:, 1T 1 .$1 15 - ASST. TV COILS anr. t,,' :,o r width, et, .51

weuh 1 1 - 3" PM SPEAKER alnico s5 magnet ..51 3 - KENRAD 6C4 $1 5 - TV CRT. SOCKETS s'" ls S1 leads 1 - 21/2" TWEETER SPEAKER for HL -Ft $1 2 - GENERAL ELECTRIC TUBES 12SK7...S1 E 5 - HI-VOLT. ANODE LEADS l, Is" S1 6 - SOCKET WRENCHES (Set)site° to 7/I6" 51 2 - GENERAL ELECTRIC TUBES '..7.25C5....51 10 - TV CARTWHEEL CONDENSERS i"kv S1 51 3 - TV ALIGNMENT TOOLS assortment tf 1 S1 2 - KENRAD TUBES 6SH7 1 - LB. SPOOL ROSIN CORE SOLDER Si 3 - TV ALIGNMENT TOOLS assortment «2 ...$1 2 - PREMIER TUBES .^;5005 51 HANDY WAY TO ORDER -Simply tear nut advertisement is 3 TV ALIGNMENT 4 KENRAD TUBES _--1-1LE3 .51 and pencil mark items wanted (X in square sufficient); - TOOLS assortment /1..3...51 - enclose with money order or check. You will receive a 3 - TV ALIGNMENT TOOLS assortment 54 ...51 4 - RCA TUBES "12SR7 Si new copy of this ad for re- orders. 3 - TV ALIGNMENT TOOLS assortment í5...51 3 - KENRAD 195 51 ON SMALL ORDERS -Include stamps is postage, eXCess EACH ALIGNMENT TOUI. in different and valued at over $ 1. will be refunded. Larger orders shipped express collect. Free -CONDENSER and RESISTOR CODE CHARTS with every order

TELEPHONE BROOKS RADIO &TV CORP., 84VeseySt., Dept. A, New York 1, N.Y. COrtland 7.2359

AUGUST, 1959 111

www.americanradiohistory.com NOTEWORTHY CIRCUITS (Continued) can make money load resistances of the tubes, the current amplitudes of the first three signals are set at 1 ma and the amplitude of the fourth signal is adjusted at 0.5 SERVICING RADIOS ma. In this way we get seven steps at YO 0.5 -ma intervals (Fig. 2). The staircase generator is normally Radio's back -stronger than ever -over 12 million sets sold fed 100 volts B plus. If this value is last year alone! But -they're trickier than ever to service. increased to 200 volts, we will get seven steps at 1 -ma intervals. In any case, You've got transistor sets, FM .sets, printed circuit sets, IP(VI-e) foreign sets. Here's a book that tells you how to handle any and all of them quickly -easily -and profitably. Yes, you can Ip(Vl-b) make money in the new radio revival. The author lists hun- Ip(V2-a) dreds of troubles alphabetically, gives you tips on spotting Ip(V2-b) and fixing all kinds of troubles in minutes. Four helpful sections -Receivers, Techniques, Servicing -and a selection of charts for speedy servicing. Here's a book that will double ITOTAL your radio servicing income in no time at all. Get your copy now. RAPID RADIO REPAIR the 100 or 200 volts B plus must be By G. Heath HOW TO GET THIS $4.60 BOOK FOR ONLY $3.35 Warren regulated for accuracy. This brand -new book in a new beautifully designed hard -covet author of Rapid TV Repair 224 pages. Deluxe gold A negative staircase is obtained in edition is sold nationally for 54.60. But through the G/L stamped herd cover. the anode circuit. A positive staircase TECHNICIANS' BOOK CLUB y ou can get it and others equally List price valuable for only $3.35. $4.60 could be obtained in the cathode circuit. In actual equipment a combination of THE G/L TECHNICIANS' A DISCOUNT OF 27%! mittance. If you don't switches allows you to use only a BOOK CLUB Through mass printing and just send it back. restricted number of steps or to main- direct has helped thousands of distribution we can A new book is published tain the current at a fixed value corre- service technicians every- offer you these $4.60 books every three months - you sponding to one of these steps. -A. V. J. where AT THE WHOLESALE receive your personal Martin PRICE OF $3.35 - and we copy on the same No- Learn More pay the postage! Risk inspection plan as Do Faster Servicing soon as it comes off the 15 -WATT TRANSISTOR How the Club Works press. Earn More Money AMPLIFIER To enroll, select the book Keep only the books you Save money on the books they you want on the coupon want -pay only for those Outside of four power transistors, need to get ahead. b e l o w . S E N D N O you keep. few parts are needed to build this unit. MONEY. Please select You to a mini- At 10 watts out (15 watts is the only one book! The one agree take Here's how it can help youl mum of only 4 books you choose will be sent - amplifier's maximum rating) power This unique club offers over the whole enroll- gain is 26 db. Frequency response, down deluxe hard -cover editions to you on a No -Risk 10- ment period. You may of today's best practical day inspection plan. cancel anytime after 3 db at 40 and 18,000 cycles, is depend- servicing and theory books If you like the book keep that. No time limit - no ent on the quality of the transformers. by well known authors AT it and send us your re- contract to sign. V 1,2,3,4- 2N378-A, 2N351-A, OR 2N350-A If you prefer -select any one of these books TV -It's a Cinch -By E. Aisberg. All about TV theory from studio to picture tube. writ Servicing Transistor Radios -By Leonard D'Airo. ten in breezy comversat ional style illustrated with hun- Techniques for servicing these tricky sets. dreds of specially -drawn humorous sketches. Oscilloscope Techniques-By Alfred Haas. Servicing Record Changers -By Harry Mileaf. Photos of hundreds of scope patterns -and their sig- Make extra money servicing changers. nificance. The V.T.V.M. -By Rhys Samuel. TV Radio Tube Sol and Troubles -By Heller. Get more out of this versatile instrument. New symptom analysis technique shows you how to Z=20KCT track down tube troubles In minutes. Sweep and Marker Generators for Television Rapid TV Repair -By G. Warren Heath. and Radio -By Robert G. Middleton. TI How to get to the heart of tough TV troubles in min- A must for television servicing. utes. Lists hundreds of troubles alphabetically -gives causes, symptoms, cures. No theory -all practical data. Probes -By Bruno Zucconi and Martin Clifford. INPUT Time -saving trouble -shooting charts. How to use probes for better servicing with today's complex test instruments. Servicing Color TV -By Robert G. Middleton. Answers all your questions about chroma circuits, matrix The Oscilloscope -By George Zwick. testing, the flyback system, test equipment and much Are you getting full use of your 'scope/ This book more. Helpful trouble -shooting charts. shows you howl

SEND IN THIS COUPON TODAY SEND GERNSBACK LIBRARY, INC., Dept. 09T NO MONEY! 154 West 14th St., New York 11, N.Y. MAIL me THIS COUPON Enroll in the G/L TECHNICIANS' BOOK CLUB. TODAY! Begin my membership with the book checked below. Please check one only. Harmonic distortion at 1,000 cycles is RAPID RADIO SERVICING COLOR TV less than 1%. A suitable output trans- REPAIR TV -IT'S A CINCH You have nothing to SERVICING THE V.T.V.M. former is the Stancor TA -14 rated at TRANSISTOR RADIOS SWEEP AND MARKER 10 watts has a 24 -ohm center - lose everything to OSCILLOSCOPE GENERATORS -it - TECHNIQUES SERVICING RECORD tapped primary. Another useful unit is TV and RADIO TUBE CHANGERS gain! Examine the TROUBLES PROBES Lafayette Radio's TR -94 -also rated at books at our risk. RAPID TV REPAIR THE OSCILLOSCOPE 10 watts -use the 24 -ohm primary. The Name schematic shows a battery power supply. Stay ahead in servicing -keep up please print However, a well filtered do supply could with the new techniques, circuits, Street also be used. V1, 2, 3 and 4 should be devices. New books on timely identical types. Motorola Semiconduc- topics now in preparation. City Zone. ..State tor Spec Sheet END

112 RADIO -ELECTRONICS

www.americanradiohistory.com C338 and C340. The two capacitors were replaced (watch the voltage ratings of these units) and horizontal drive reduced to a minimum. This cured the trouble. The defect was caused by arcing within the capacitors -one or both. Capacitor C335 was also replaced to be on the safe side. Similar symptoms occur with intermittent failure of C335.- James A. McRoberts NEW STEREO RECEIVER HALLICRAFTERS ß1400 NO ONE BUT BOGEN, builder of over In this chassis and some other types RCA T100, T120, T124 one million high -fidelity and using a horizontal deflection system An annoying hum in the sound of sound -distribution components, similar to that shown in the diagram, one or more channels, similar to that of could have engineered the new a peculiar form of horizontal insta- bad filter capacitor or intercarrier buzz, SRB 20 stereo receiver. A superb bility occurred. Certain sections of the in these split- carrier models is often all -in -one instrument, its a picture would jitter at irregular in- caused by the local oscillator being out highly sensitive FM -AM stereo tervals, both in time and place, with an of range of the fine -tuning control. tuner, a versatile audio control accompanying dark spot on the picture. Since the sound section uses an ordinary center, a magnificent 20 waft (10 Using a plastic toy stethescope (such discriminator without any limiter stage, per channel) stereo amplifier, as sold with toy doctor's kits), a pop- we can see how AM can easily creep in. and it's only $199.50 -a price ping sound that coincided with the in- When aligning the oscillator trimmer, you'd expect to pay for a com- stability could be heard near capacitors maximum sound is found at two parable tuner alone! YEARS AHEAD. Bogen's engineer- r-----r, PLUG TO AGC SEVER PLATE ing staff (largest of any sound- 6BQ6 -GT I B3-GT HORIZ OUTPUT HV RECT IRG-58/U = HORIZ DEFL COILS equipment maker) has designed 47µµf/ 2 KV the SRB 20 to be years ahead in 1F- performance as well as price. C 340 C338 Here is all the flexibility...aU the .001 I KV C335 distortion -free tone quality... all 6W4 -GT -11.1 PLUG d SOCKET the power you need for perfect FLYBACK DAMPER E- stereo pleasure. Reflecting over TRANS WIDTH 5 RFC HORIZ .047 25 years of experience gained in t LIN ° T °I building specialized sound sys- L 3 RFC 6 7 tems for schools, theatres, indus- áò trial plants and offices, in addition to high fidelity components, the SRB 20 provides the faithful SENCORE sound reproduction listeners have learned to expect from Save LEAKAGE CHECKER Bogen. Enjoy the beautifully Check these outstanding New Features styled SRB 20 yourself or install The LC3 provides all these new improved features in addition it for your customers -either way Time to those employed in earlier leakage or "grid circuit" testers. you get the best buy in hi -fi t _day! A must for any TV service technician. * Checks 156 different tube types -more than any with other "grid ciructt" type checker. Includes UHF and latest type tubes. * Checks picture tubes without removing tube from cabinet or chassis. SECORE * New Roll Chart prevents obsolescence -just dial the tube type and save time. Chart is easily replaced at no extra cost. * Provides instant filament checks on "Fil.Check" posi. Model LC -3 See other tion -no need to carry a second filament checker. * Capacitor checks simplified. SENCORE * Two spare preheating sockets to cut down testing time. $ 2895 ads in this In stock at your /ono/ parts distributor. DEALER NET issve Really Whips SERVICE INSTRUMENTS CORPORATION 121 Official Road, Addison, Illinois Dogs t Tough BOGEN SRB 20 STEREO RECEIVER CONTROLS: Selector. FM Tuning. AM Tuning. Separate Bass and Treble servicemen NO -NOISE for each channel (lock for simul- VOLUME CONTROL iits sasis NOW everywhere and AVAILABLE taneous control of both). Volume for CONTACT RESTORER each channel (correct imbalance, Cleans Protects insist on the Lubricates then lock for simultaneous control). NOT A CARBON TET GENUINE SOLUTION On -Off Power. FM On -Off and AFC AT FREEYOUR out. AM On -Off and Multiplex Bottle Spray Con 5" JOBBER'S "N o $100 S225 -----MAIL COUPON NOW r s BOGEN-PRESTO li OISE" Net TTon Net T o EXTIENDER CO., PARAbíU9, Iw J. Servicemenen seet en A Division the Siegler With of Corporation NO PIN Please send me illustrated booklet, -NOISE It POINT APPLICATIONS! f TUNER 41 "Understanding High Fidelity." 64- -TONIC page explanation of hi -fi and stereo. With PERMA -FILM Enclosed is 25c. 6 Oz. Spray Can Economical -a 6 Oz . little does a lot. Aerosol Can NO NOISE Cleans, lubricates. Name and title estores cl RUBBER tuners, lading - 25 35 wafer type. COAT Beware Of Louie, non- inflammable. SPRAY Servicemene Use flor TV, Net To Insulates Waterproo Address Cheap Substitutes! radio and FM. Sery i<, men Protects Communipaw Avenue Jersey City 4, N. J. City Zone -State ELECTRONIC CHEMICAL CORP. 813 J AUGUST, 1959 113

www.americanradiohistory.com TECHNOTES (Continued) [PURCHASING settings. However, the correct setting ELECTRONIC of the trimmer is where you get max- ORGAN imum sound and good picture quality. A HI -FI for your HOME! If you have maximum sound, but a poor picture, screw the trimmer in SYSTEM? BUILD-IT- farther and see if you hit another - point where you get good sound and PARTIAL LIST ' i' '' YOURSELF picture. When making these adjust- Send Us OF BRANDS ments, set the fine -tuning control at IN STOCK SAVE! the center of its range to allow for Your Altec Lansing Now you can own a professional electronic organ and future oscillator drift. -G. P. Oberto Electrovoice save up to 50% on an easy pay Jensen -as- you -build plan... Hartley The world famous ARTISAN ORGAN -in 14 models RECORDER List Of University from the popular 2- manual Home entertainment style HEAD REPAIR Acoustic Research to the majestic 4- manual Theatre and Church style is Jansren Many erase, record and reproduce W.,arf edale now available in kit form. Simple step -by -step instruc- tape recorder heads can be repaired. Components tions, pictorial diagrams Ka risen and schematics make this an All that is needed are spare time and V,king ideal spare -time project for anyone. Conc ertone a magnifier in addition to the usual For A Bell G.E. FREE LITERATURE on REQUEST Weathers shop tools. Harman -Kardon Get the Artisan Story before you purchase The photograph shows an erase head Eico Pilot any Organ, Kit or commercial model. Package Sherwood that has been opened. One terminal lug A cro sou nd ARTISAN ,.,naì New Home of was removed because the wire leading Fisher MUSIC HALL ARTISAN ORGANS to Quotation Bogen Leak it had corroded. Fortunately, the Dy na kit ORGAN H. H. Scott KITS WE WON'T BE Fe rrograph and REMOVED = Tan be rg TERMINAL - - --- COMPONENTS UNDERSOLD! Pent ron Ampro VM All merchandise Revere ELECTRONIC OUTER is brand new, fac- Challenger Wollensak ORGAN ARTS, INC. TUR tory fresh & guar- PICKED Garrard 4949 YORK BLVD., Dept. i;E -lì UP anteed. Miracord LOS ANGELES 42, CALIF. Glaser- Steers Rek -O -Kut Components WIRE AIREX Nerelco END Fairchild Pickering Gray RADIO Aed'o Tape Conrac CORPORATION Wellcor Cabinets TV PICTURE TUBES 64 -RE Cortlandt St., N.Y. 7, CO 7 -2137 At Lowest Prices wire led to the outer layer of the coil. OBP4 .... $ 7.95 7BP4 ....$ 9.95 21AMP4..$15.75 2LP4 8.50 7CP4 .... 17.00 2IATP4.... 15.75 The outer turn was picked away, .hav- 4B/CP4 9.95 7GP4 .... 17.60 21AUP4-..- 15.75 6DP4 12.00 7HP4 .... 12.50 21EP4 ... 13.50 ing been pushed underneath the coil. It 6EP4 - 12.75 7LP4 .... 11.50 21FP4 _-. 14.50 will be to 6GP4 14.50 70P4 .... 9.95 21 W P4 .... 14.00 brought up the front slot or 6KP4 9.95 7TP4 .... 17.00 21YP4 .... 14.50 opening and cemented before it is sol- LOOK 6L P4 10.95 9AP4 .... 16.00 2IZP4 .... 13.50 no . . further if you're 6RP4 9.95 20C P4 ._. 13.50 24CP4 23.50 dered to the terminal lug again. The searching for hi -fi sav- 6WP4 12.00 20HP4 .... 14.50 24 D P4 24.50 ings. Write us your re- 6PT4 9.95 21AP4 .. 22.10 27 E P4 ._ 39.95 cement holds the wire in place during quirements now. 7A V P4- 12.50 2IALP4__. 15.75 27RP4 39.95 soldering.- Lawrence Shaw Key Electronics Company 1 year warranty Aluminized Tubes $6.00 more than above prices. 120 -A Liberty St.. N.Y. 6, N.Y. Prices include the return of an acceptable similar EV 4-6071 tube under vac nnl. These tubes are manufactured CASCODE RF STAGE Iron reprocessed sed glass bulbs. All parts and materials including u the electron gun are brand new. On all TV receivers using a cascode ALI. PRICES FOB CHICAGO, ILLINOIS. De- posit requited, rf stage (6BQ7, 6BZ7, 6BK7), if the time of return. 25 á deposit required on COD shipments. Old tube is shorted always look AUDIO DISTORTION METER tubes must be returned prepaid. Tubes for a shipped Rail Express. charred voltage New, LOW PRICED Intermodulation (IM) Distor- isolating resistor- tion Meter. Anyone can Test and Adjust Amplifiers WRITE FOR COMPLETE LIST. usually between 470 and 1,500 ohms as Manufacturers Do. Especially Useful for Hi -Fi - Hobbyists, Kit Builders and Service Shops. Shipped in the second half of the tube's circuit. POSTPAID Ready to Operate for $22.95. Satisfac- -PICTURE TUBE OUTLET -- tion Guaranteed or Money Refunded. This is a must to check after a bad tube 3032 Milwaukee Ave., Chicago 18, III. is found, NEWBURY ENGINEERING CO. if locals come through fairly Box 144 Bradford. N.H. Dickens 2 -2048 well and semi -locals far below normal. on -W. G. Eslick END

VOES N-tzADIO REPPJR: I SAVE A Low Cost rnIME TRANSISTOR RADIO . Wrtn BATTERY ELIMINATOR Here is a complete isolated power supply especially designed to replace batteries during repair time of all transistor radios. * Supplies up to 24V D.0 * Provides 100ma con- ?144w-731'14 1 stant A to the and 200ma on peaks "Twin" * Meter indicates either volt - SENCORE tage or current * 1.5 volt biasing tap for Philco TRC4 Transistor and Sylvania Transistor Radios Checker See other SENCORE SERVICE Instruments Corp. ads in this issue. 121 Official Road, AT LEADING PARTS DISTRIBUTORS Addison III. "Ten bucks to fix a ghost!"

114 RADIO -ELECTRONICS

www.americanradiohistory.com ...... 14010. PLIERS have a ...

ELECTRONIC PHASE SHIFTER Patent No. 2,859,342 Victor A. M1fisek, .Nashua, N. H. (Assigned to Raytheon Mfg. Co., Waltham, Mass.) No. 62CG illustrated 7//mi In a tetrode, screen -grid current is controlled by plate and control Arid voltages (Figs. 1 -a and Transverse Cutter 1 -bl. The current rises as the grid voltage goes more positive, but falls with increasing plate GRIP voltage. This out -of -phase effect is used here. CUSHION /

Plier handles have dipped 1G2 G2 plastic coating ... permanent, comfortable. Heads polished and buffed to a "mirror finish ". Ep EGI Fig.l-a Fig.l-b All pliers available ... See Your Distributor !

In Fig. 2 the ac signal is applied to the plate through capacitor C and to the control grid through resistor R2. The do voltages on plate and grid are adjusted as required to cancel screen output with the alternating -current sig- óives pliers a 11feel" that inspires Craftsmanship! nal applied. Once balanced, the plate effect will predomi- nate if R1 is increased. On the other hand, the X C E L I T E g INCORPORATED ORCHARD PARK , NEW YORK Canada: Charles W. Pointon, Ltd., Toronto PREFERRED BY THE EXPERTS OUT

-I-

BATT 2 + COYNE TRAINS YOU COYNE Fig.2 TIME QUALITY IN SPARE grid effect will be larger if RI is reduced. This TRAINING AT HOME becomes the phase control, because in one case the screen output will be in phase with the AT LOWEST signal, and in the other it will be out of phase. This circuit can energize reversible motors which depend on currents that are in phase or out of phase. TV POWER -LINE TELammo. Eds CciL.°R DISTORTION METER Patent No. 2,875,403 Only from famous COYNE do you get this modern up -to-the minute TV Home Training. Roswell W. Gilbert. Montclair. :N.J. (Assigned to Daystrom, Inc., Murray Hill. N. J.) Easy to follow instructions -fully illustrated This describes an accurate and practical ac with 2150 photos and diagrams. Not an old power -line distortion measuring instrument. Radio Course with Television tacked on. In- Briefly, the 60 -cycle fundamental is trapped by a cludes UHF and COLOR TV. Personal guid- parallel -T network and the remaining harmonics are rectified and measured. ance by Coyne Staff. Practical 7th Guides to help you EARN MONEY QUICKLY IN A BUSI- 8K 20K TV-RADIO SALES AND SERVICE NESS -part time or full time. COSTS MUCH LESS -pay only for training-no costly "put together kits." SEND TODAY FOR FREE BOOK

SEND COUPON or write to address be.uw .+ for Free Rook and full details including EASY PAYMENT PLAN. NO COST OR OBLIGA- TION -NO SALESMAN WILL CALL. 500 il B. W. COOKE, Ir., FOUNDED 1899 Pres. "The only thing that will draw CHARTERED AS AN EDUCATIONAL INSTITUTION N0- FOR PROFIT 5K him out, Dearie, is a Jensen 1501 W. Congress Pkwy. Dept. C9 -H5, Chicago 7, III. 60 l AC LINE needle." COYNE Television Home Training Div. -I RI New Coyne Building, Dept. C9 -H5, 1501 W. Congress Pkwy., Chicago 7, Ill. Send FREE BOOK and details of your Television Training offer. V. DISTORTION Home Name Address L_City State

AUGUST, 1959 115

www.americanradiohistory.com PATENTS (Continued)

The device is calibrated using 180 cycles, since distortion in the field usually shows up mostly in the third harmonic of the power-line frequency. Rl is set so the meter reads full scale with 11 volts of 180 -cycle signal applied to the input and switch S depressed so the T- network is in the circuit. Then 110 volts 60 cycles is applied to the input and R2 is set for full -scale deflection of ARKAY CS -28 the meter. Vernier resistance adjustment is available in STEREO AMP /PRE -AMP the arms of the T- network. This is required to compensate for possible error in the fixed capaci- -, COMPLETE { r tors. Rl and R2 may be readjusted in the field if CONTROL CENTER necessary.

Full 28 watts stereo or monaural, 60 watts peak 14 watts each channel reverse stereo balance control two-channel gain GUIDED LENS control full range bass and treble controls IM distortion, 4 Stops record to 1 damage! harmonic distortion, 1% 30-20,000 cps dual Patent No. 2,869,803 output pre -amp 2V jacks speaker outputs, 4, 8, 16, 32 ohms response, James D. ,$1eGee, Ealing, London 20- 20.000 cps push -pull E184 Williamson circuit. Do you know all your records contain dust in (Assigned to Electric & Muniral Wired and tested $99.95 Easy -to-build Kit $6495 every inch of groove? This unretouched photo- Industries, Ltd., Hayes, England) This is about a controlled lens mounted on a ARKAY ST -11 AM -FM micrograph, courtesy of Wireless World guided missile to keep the target image in view STEREO TUNER at all times. Ordinarily the missile may change Here, for the first time, is an AM. (London), shows how much is removed by one FM STEREO Tuner within the reach of every audiophile. Unmatched by use of the ESL Dust Bug. If not removed, these units costing twice the price, the ST -It is two distinct receivers in particles cause one featuring 4 vV. for 20 rib quieting. Variable AFC. Single front noise (especially on stereo panel switch controls AM, FM or STEREO selection. 1 records), and also inflict wired and tested $74.50 Easy -to-build Kit $49'95 permanent damage upon valuable records and styli.

The only safe, effective method of cleaning records is the ESL Dust Bug, acclaimed by more

ARKAY SPA -55 ARKAY SP -6 STEREO than 200,000 delighted users throughout the STEREO AMP CONTROL CENTER Versatile stereo preamp with world. It's easy, too -it cleans automatically two 27l a watt distortion-free dual inputs and outputs. Hi -Id hi -ti amplifiers for stereo. Or filters, reverse position, bal. while the record is GYRO use as 55 watt monaural am- being played. Only $5.75 plìfier, ance Control. Less cover. CONTROL complete (record changer model only Easy-to -build Kit$6495 Easy -to -build Kit$3995 $4.75) Wired and tested $79.95 Wired and tested $62.95 FOR LISTENING AT ITS BEST See and hear ARKAY Kits at your dealer. FREE! catalog. Write Dept. RE. Stereo booklet and RUDDER All prices 5% higher nest of Mississippi Electro -Sonic Laboratories, Inc.

88 -06 VanWyckkExpressway V Richmond Hill N.Y. Dept E 35 -54 36th St Long Island City 6, NY

direction from time to time during flight, correction being made continually by a gyro. These changes tend to blur the image transmitted by the TV camera. ATTENTION A variable -angle camera lens is coupled to the gyro. When the gyro moves to correct for error in missile flight), an opposite movement is im- Service Technicians' Associations parted to the lens. Thus the picture remains in view and steady no matter how the missile may move around during its flight. This gives a Club Members steady image. ENn Student Groups

Special subscription rates to RADIO- ELECTRONICS are available to associations,

clubs, schools, employee groups, etc. For information write- G. Aliquo HEAI=2ING

Radio -Electronics 154 West 14th St., New York 11, N. Y.

------rww SAVE TIME 2 Adaptors in 1 With- SENCORE "VIBRA- DAPTOR" BEN-CORM Checks Both Three and Four Prong Vibrators Merely plug into any tube checker. Set for 6AX4 (or 6SN7) for 6 Volt Vibrators and 12AX4 or 125N7) I for 12 Volt Vibrators. Two lamps viewed through tap NOW - of adaptor indicate whether or not Vibrator needs re- / Vibrators placing. Rugged -Made of steel. Replaceable but Check unbreakable #51 indicating Lamps. Operates easily I in ANY with Sencore LC -3 Leakage Checker. Complete I SA(FRNo ker instructions screened on front. L Tube Chec In stock of your loco! ports distributor. - - SERVICE INSTRUMENTS CORPORATION -w._ 121 Official Road, Addison, lil mots -- "If I buy one now, will I be able to add See other SENCORE ads in this issue. ""- ....- stereo later ?" 116 - RADIO -ELECTRONICS

www.americanradiohistory.com Mr. SERVICEMAN You make more profits on a /dSINESSa Stereo pickups with PICKERING'S NEW Program! PE

Sylvania Electric Products launched Think of it!... you can make 100% or EVERYTHING YOU NEED an electron -tube promotion campaign more in profit on Stereo conversions FOR STEREO CONVERSION! at the consumer level, featuring a $2 and installation of Stereo pickups for rebate on the purchase of a Sylvania replacement! STANTON STEREO KableKits receiving tube in combination with a D. W. FOR FOR CONVERTING Silver Screen 85 picture tube. CONVERTING M1NUEl CHANGERS TORE GRMS

NEW! Low cost stereo cable assembly for ccnverting automatic changers and manual tone arms. Prefab- ricated insulated and fully shielded harness assembly with all plugs and connector clips soldered ... ready for instant installation! No soldering required for normal installation. Harness length 4 feet, comes complete with cable retention clips. Get into the profitable stereo high fidelity busi- Model 603 Stereo KableKit for three wire systems ..$2.98 ness where experienced and quality conscious Model Stereo KableKit for systers..$3.98 technicians are needed. Pickering's NEW pro- 604 four wire gram makes it possible for you to buy the ASK FOR PICKERING AT YOUR 1OBBER STANTON Stereo FLUXVALVE and the STANTON ... EASIER TO SELL AND INSTALL. Gunn (left), vice president, sales, of Stereo KableKit from your wholesaler so you make your full markup in addition to your serv- FREE! Pickering Service -File, complete technical file Sylvania Electronic Tubes, and Warren on quality products by Pickering. Includes valuable bul L. Smith, president of Warren Radio ice charges. Call your wholesale jobber today and letins on hum elimination, installation, maintenance, take full advantage of this profitable business, etc. Co., Toledo, Ohio, are shown manipu- Address Dept.G -89 Ior your free Service-File. lating puppets used to kick off the campaign. foi those who con [houri the äderence °,,., oeeurr MON nana. mmouere er Astatic Corp., Conneaut, Ohio, is PICKERING 8 COMPANY, INC., Plainview, N. V. merchandising its plug -in phono cartridges with a new colorful pilfer -proof NOW, THE DYNAMIC most needed PORTABLE TUBE TESTER THAT DOES EVERYTHING most wanted

A -shape counter display. It holds 12 cartridges, each packed in a sturdy transparent plastic box. CBS Electronics, Danvers, Mass., received an award from NATESA for outstanding service in creating better customer relations. A. L. Chapman,

New V1003 tests 99% of all radio and TV tubes plus transistors and portable radio batteries! a RI the No other tester like it at any price. Not only helps you do FUSEMAa S TER ! better, faster TV -radio servicing, but sells more tubes. Aisa. dealer- serviceman's fuse rack all transistors and port- checks . CBS Electronics president (second from able batteries under load (a for wall mounting is Vis -U -All exclusive(. Does all left), shown receiving the award from this with just 6 sockets, 3 Vincent Lutz, NATESA president. A. knobs . simplicity un- ...dealer-serviceman's fuse C. W. Saunders (left), educational di- equalled! New and practical features galore! requirements at a glance rector of NATESA, R. V. Bontecou, ONLY $129 -00 CBS Electronics vice president of mar- For further information, keting, and J. H. Hauser, contact your nearest Littelfuse Distributor. distributor Write VIS -U - ALL sales manager for the company (right), PRODUCTS CO. look on. for 640 EASTERN, 5. E. LITTELFUSE Westinghouse Electronic Tube Div., GRAND RAPIDS 6, Elmira, N.Y., is offering over $50,000 Details MICHIGAN D E S P L A I N E S , I L L I N O I S in prizes in four Giant Jackpot contests AUGUST, 1959 117

www.americanradiohistory.com BUSINESS AND PEOPLE (Continued) TARZIAN Offers 48 -Hour, This is the busi- nesslike approach Direct Factory Service to service record PROFESSIONAL keeping. Tripli- on Tuner Repairs cate forms serve technicians as order form, invoice and office record, with use spaces for complete information on every job. Separáte listings for receiving OFFICIAL tubes, pix tube, parts, serial numbers, labor and ORDER BOOKS tax charges, sig- That's right. Net, $7.50 per unit and $15 natures, etc. -75c for TV -radio dealers and service tech- for UV combinations, including ALL for every a book, $6.50 for nicians. A collection dust -proof large of merchan- replacement parts. 90 -day warranty box of 10. In stock at dise, including a Ford station wagon against defective workmanship and TV -RADIO your distributor. and various appliances, will be awarded. parts failure. Tuners repaired on ap- Write for your Sherwood Electronic Laboratories, proved, open accounts. Replacements service free folder de- offered at these prices* on tuners not scribing Dave Chicago, manufacturer of hi -fi tuners, repairable: Rice's OFFICIAL amplifiers and home music centers, pre- call ORDER VHF 12 position tuner . . $22.00 BOOKS, sented its top sales award to Don Bacher including VHF 13 or 16 position an actual size sample tuner 23.00 copy of the handy VHF /UHF combination 25.00 order form. UHF only 15.50 *Subject to change For customer's prices on every Tarzian -made tuners are easily replacement part, identified by this stamping on the plus flat rate and unit. When inquiring about re- hourly service placements for other than Tarzian -made charge data, tuners, always give tube complement regional and shaft length national, Dave ... .. filament voltage... Rice's series or shunt heater OFFICIAL & ... IF frequency PRICING DIGEST, of Belchamber French Co., San Fran- and chassis identification. Use this listing over 63,000 cisco, for the greatest percent increase address for fast, 48 -hour service: items. $2.50. in sales over the previous year. Edward SARKES TARZIAN, Inc. ELECTRONIC S. Miller, Sherwood general manager (left), is shown making the award. Att.: Service Mgr., Tuner Division PUBLISHING CO., INC. East Hillside Drive Arco Electron- Bloomington, Indiana 180 N. WACKER DRIVE ics, Inc., CHICAGO 6, ILLINOIS New York, is now pack- aging SEPTEMBER Issue its Elmenco On Sale AUGUST 25th DP dipped Mylar at all better parts distributors i and newsstands. paper capacitors in moisture - proof ENGINEERING ItF1'OUDING TAPE transparent 5 -Pak prepare for un- l'ItF:111 "1 bags. limited opportu- B. S. DEGREE Qt'.tLI1'l' J` tutiesoftheb:lee- 10 day money back guarantee ironic Age! Stu- IN 27 MONTHS Dr. Herbert Trotter, Jr. (top left), dents ,study- engineering under accelerated program leading 12110' .Acetate 3 for $3.90 ISO°, \lthtr l for $6.0(I 1800' Acetate 3 for -1.95 2490' Mylar 3 for was elected a senior vice to B.S. degree in 27 mo.; or standard 4 -yr. - program lead- 9.60 president ing to B.E. degree in 36 mo. B.S. degree (36 mo.) in Lot. 01 any Ill a.plvuetlt IIIyé di..count engineering of Sylvania Math., Chem.. Physics. Year -round classes. Compre- Hi -Fi Components, Kit., Tape Recorder.. Get our low, Electric Prod- hensive training in electronics, television, advanced radio low prices by return mail before you buy. ucts. He had been executive vice presi- theory and design, math., nuclear physics and elec. eng. WHOLESALE CATALOG FREE Also prep courses. Low rate. Earn board. C.I. approved. dent of the Sharples Co. James H. Enter Sept., Dec., Starch., June. Catalog. AUDIO FAIR, 1799R 1st Ave, New York 28, New York INDIANA TECHNICAL COLLEGE 1789 E. Washington Blvd., Fort Wayne 2, Indiana I MAIL ORDER HI -FI Please send me free information on B.S. ENGINEERING DEGREE IN 27 MONTHS as checked. You can 196v purchase all your 411 -Et from one O Electronics Chemical Aeronautical reliable source and be assured of perfect delivery. D Civil O Mechanical D Electrical Cat:ston makes delivery from NY stock on most B.E. DEGREE IN 36 MO. in: D Electrical (Power or Iii -I'i, Recorders and tape within 24 boon. SEND Aeronautical O Chemical Electronics) US A LIST OF YOUR HI -FI REQUIREMENTS D Civil o Mechanical D Metallurgical B.S. DEGREE IN FOR OUR WHOLESALE QUOTATION and our 36 MO. in: Math. D Chem. D Physics O FREE wholesale catalogue. Name CARSTON STUDIOS Address New York 28.N.Y.

High Fidelity 3 SPEAKER SYSTEMS Here is a perfectly matched team with 3 -way crossover network. Kit includes 12" woofer; 8" midrange; Brewster III (top right), was appointed 3tn" tweeter; hardware and network. Model 3W20 vice president, marketing, of Sylvania . . . audiophile net $39.00. Electronic Systems. Samuel A. Fergu- Beautiful cabinets available in variety of modern son vice finishes (lower left), was named presi- and designs . . . write for FREE literature. Leading distributors Corry OXFORD dent and general manager, Mountain COMPONENTS, INC. View, (Calif.) operations, and Dr. 556 West Monroe Street Edwin G. Schneider (lower right), vice OXFORD Chicago 6, Illinois president, research and engineering. Export: Roburn Agencies, New York In Canada. Atlas Radio, Toronto Brewster was formerly director of cus- OXFORD BRANDS: Supreme Transformers, Hudson Lamps, Tempo Hi -Fi, Oxford Speakers 8 Rear Deck Kits. tomer relations; Ferguson, manager of 118 RADIO -ELECTRONICS

www.americanradiohistory.com BUSINESS AND PEOPLE (Continued) GET INTO ELECTRONICS TODAY'S TOP OPPORTUNITY FIELD Mountain View operations, and Dr. Schneider, chief engineer of Sylvania ANOTHER GREAT Electronic Systems. Both Brewster and LECTRICITY Dr. Schneider will have their offices in irELECTRONICS Waltham, Mass. ORRadio Industries, Opelika, Ala., TRIO® has designed a new Two -Way Profit TV ANTENNA FEATURE E LEVISI ON Pack for TV and radio service tech- RADIO - ELECTRONICS nicians. It includes an assortment of TRAIN IN THE NEW SHOP -LABS OF wing and dipole OLDEST, BEST wing director EQUIPPED SCHOOL TAPE RECORDER COYNE OF ITS KIND IN U.S. SERVICE in Chicago - Electronic Center of the World. Pre- au Masts pare for a better job and a successful future in TOP OPPORTUNITY FIELD. Train on real equipment -no advanced education or previous experience 1 needed. Lifetime employment service to graduates. Finance Plan - enroll now, pay most of tuition later. Part time employment help to students. FREE BOOK -Mail Coupon or write to address a tape -recorder below for Big Free Illustrated Book - "Guide to 12 reels of Irish tape, Careers." Whether you prefer ELECTRICITY - service manual and an identifying ban- ELECTRONICS, TELEVISION -RADIO ELEC- TRONICS OR COMBINED ELECTRONICS ner. The manual was prepared in co- Today's most powerful combination. TRAINING, all offered. The Wing Dipole contains 3 active this book describes training operation with Howard W. Sams & Co., elements on the highs, forward Vee Information comes by mail. No obligation Inc. to the low band section, plus inte- and NO SALESMAN WILL CALL. grated director. The Wing Director B. W. Cooke, Jr., Pres. Founded 1899 Harold F. obtains maximOm results from the Bersche, manager, Wing Dipole. COYNE ELECTRICAL SCHOOL m e r c h a n- Chartered as an Educational Institution Not for Profit 1501 W. Congress Pkwy., Chicago 7, III., Dept. C9 -5A dising, Distributor Just one of the features that makes Trio the Products Dept., most advanced TV Antennas in the world. ÌCoyne Electrical School R C A Electron Choose from Trio's complete Zephyr and New Coyne Building, DepI.C9.5A Tube Div., Har- Color Series Antennas. l 1501 W. Congress Pkwy., Chicago 7, III. Send FREE book "Guide to Careers" and rison, N. J., was details of all training you offer. promoted to man- Name ager, Distributor Products Dept. Address James R. Bost- City wick joined Heath GIIIGGSVILLE, ILLINOIS State Co., Benton Har- (I understand no Salesman will call) bor, Mich., as as- sistant to the vice M president. H e r New! Improved! comes to the company from Temco TRANSISTOR Aircraft Corp., CHECKER where he was a staff engineer. America's newest, most David Hughes, a popular test instrument Simple to Operate. Controls are accur- sales engineer in ately set for each transistor by the Chicago terri- referring fo replaceable set-up chart on rear. Test leads or socket tory for Hickok provides for fast hook -up. Electrical Instru- NOW CHECKS: ment Co., Cleve- * Transistors for opens, shorts, leakage and current gain. land, was named Only tester that tests power transistors as used in car radio outputs. tenet become director of mar- ebselete. Diodes checks forward to reverse current ratio keting. * Crystal tItroyed by Frank M. Hickey was appointed mer- on all diodes. leading * Selenium Rectifiers checks forward and reverse currents. manufacturers. chandising manager for industrial prod- SERVICE INSTRUMENTS CORPORATION NI121 OFFICIAL ROAD, ADDISON, ILLINOIS At Leading Parts Distributor=_. ucts sales for CBS Electronics, Danvers, See other SENCORE ads in this issue. wilimmoimmmmmmmm Mass. George W. Tallaksen, Jr., for- SUPER MAGNET SUPER SAVING! 250 POWER AMAZING BLACK LIGHT merly with G -E, succeeds him as North- Buy this Little Giant magn. . most power- 250 -watt ultra -vio- east regional sales manager. ful de e. a sensation-s let light source. al bargain! The low TELESCOPE LENS KIT Larry Hermann price of $1.95 is less Makes fluorescent than 50% of what Make your own high powered 6 ft. articles glow in the you'd pay for this diam., is the new assist- magnet. Experiment- telescope! Kit contains 2" (!ark. Fits any ers. hobbyists will 75" focal length. ground and pol- lamp socket. For ant merchandising find hundreds of t ished objective lens and necessary en- for this powerful 4 t on. experimenting, manager for Elec- Alnico permanent eye pieces. Magnifies 50x to 250x. tertaining. unusual magnet. LIFTS 5 lbs. instructions. tro- Voice, Inc., Bu- EASILY. Limited Full lighting effects. gn:muty. meet ITEM NO. 123 1 wt. 2 lbs. chanan, Mich. He al today. Measures Ship. $3.45 will remain as Itemlay "N1.1/2;6 $1.95 $3.45 ITEM NO. 67 Special Bargain A) (P. P. S Hdlg. Chgs. 35e) product manager, (Slip. Gligs. luci (Shp. Chgs. 10c) Wolverine Div. HUDSON SPECIALTIES CO., 160 W. 14th St. Dept. RE -B -59, New York 7, N.Y. WATTHOUR METER Robert M. Andrews, advertising and full remittance rolad Leading makes- recondition- helo v. e(Beo mute to shipping charges.) of ed. Ideal for trailer parks. sales promotion manager electronic 87 33 86 123 Electric, Inc., l00-110 volts. 60 cycles. 2- products for Tung -Sol wire A.C. 5 amp. Heavy metal Name Easy Newark, N. J., was named electronics Please Print Clearly case 81/2" x 6'/4° x 5 ". planning manager for distributor sales. to install. Ship. wt. 14 lbs. Address ITEM NO. 33 T. D. Stephens was named manager of NOW ONLY $4.95 distributor sales in the Atlanta sales City Zone State (P.P. i Hdlg. Chg.. $1.25) office. END 119 AUGUST, I 9 5 9

www.americanradiohistory.com tricity, superconductivity, parametric devices, electromechanics, ferroelec- tricity, magnetostriction. Theory and FM ANTENNA applications are discussed. Ferrite materials are given considerable attention. with New Offset Clamp The book is recommended for readers who are well equipped with higher Mounts on Same Mast math. IQ

1959 SOLID -STATE CIRCUITS CONFER- as TV Antenna ENCE AUTO RADIO SERVICE DATA MANUAL, (Philadelphia), Digest of Technical Papers, edited by VOL 7. Howard W. Sams & Co., Inc., In- Robert F. Cotellessa. Publisher, Lewis Winner. 8';2 x 11 in. dianapolis 5, Indiana. 81/2 x 11 in., 240 Paper. Available from Henry G. Sparks, PP. $3.75. Moore School of Electrical Engineering, No. 7 in the continuing series covers University of Pennsylvania, 200 So. 33 St., 1956 and 1957 model car radios. Those Philadelphia 4, Pa. $4. familiar with Sams' treatment know The conference, attended by nearly that each set is shown in two or three 2,000 leading workers in the solid -state New Offset Mount photographs, and that parts list, align- field, gave birth to 40 papers, which Bright Gold Anodized ment instructions and schematic dia- appear in full or in abbreviated form in grams are given. -CG this digest. Subjects covered included reactance amplifiers, memory tech- INFRA -RED LIGHT AND ITS USES (Proj- niques, Hall ect No. 9040. Popular Optics Library). -effect devices, cryotrons, Edmund Scientific Co., 101 E. masers, twistors, photo- and avalanche Gloucester transistors New Pike, Barrington, N. J. 812 x 101/4 in. and more conventional solid - 15 pp. 750. state applications such as switching Details such electronic -optical con- circuits and rectifiers. A compendium struction projects as infra-red tele- of the latest in the solid -state field. WINEGARD scopes, microscopes and telescope -FS adapters, fire and intruder alarms and "Turnstile" GETS detection systems. Emphasis is placed FUNDAMENTALS OF RADIO AND ELEC- on the optical systems, with TRONICS (2nd Edition), edited by W. L. lenses and Everitt. Prentice 100 -MILE FM mounting distances specified. -red -Hall Inc., 70 Fifth Ave., Infra New York N.Y. 4 converter tubes and lenses are available 11. 6 x 9' in. 805 pp. $11. RECEPTION from publisher at nominal rates.-RFS Completely rewritten and updated, II this book is especially valuable to radio OFFICIAL REGISTRY OF TRANSPORTA- operators, radio and electronic tech- TION RADIO SYSTEMS. Edited by Ethel nicians, and engineers. It provides a V. Sleeper. Communication Engineering thorough review of mathematics and Non -directional ... Book Co. Monterey, Mass. 81/2 x 11 in. electrical engineering. Some of the no rotor needed 69 pp. $4. topics covered by the text are mathe- With most TV antennas A calibook listing frequencies and ad- matics of radio and electronics, direct - you cannot get good FM dresses of stations operated by taxi, current circuits, electromagnetic waves, reception. That's because TV railroad, auto emergency, motor carrier frequency modulation, color television, antennas REDUCE FM signal and highway trucking companies. In radio -wave propagation, industrial ap- to shut out FM interference on TV. Part 1, companies are listed alphabeti- plications, and an appendix of safety Get clear FM reception up to 100 cally by state and city. In Part 2, the and special radio services. -LS miles with the sensitive new listing is by frequency with call signs, location and type Winegard "Turnstile" FM antenna. of operation given. BASIC RADIO AND RADIO- RECEIVER SERVICING (2nd Edition), by Paul B. Two antennas give %e CONDUCTANCE DESIGN OF 40 power ACTIVE Zbar and Sid Schildkraut. McGraw -Hill CIRCUITS, by Keats A. Pullen, increase over single antenna. Jr. John Book Co., Inc., 330 W. 42 St., New York F. Rider, Publisher, Inc., 116 W. 14 St., Has unique offset mount -installs 36, N.Y. 131,4 x 11 in., 130 pp. $2.25. New York 11, N.Y. 6 x 9 in. 330 pp. $9.95. quickly on same mast with TV So you want to be a service techni- The author shows how antenna. Perfect 300 -ohm impedance. to design tube cian? The first step is learn electronics and transistor circuits for maximum theory and practice as Weatherized- non- corrosive, bright efficiency taught by a and minimum distortion. His good school. A thorough text will help. gold anodized finish. Send for method is based on the use of special free literature. This one is part of a series of EIA G (conductance) curves which indicate laboratory manuals. It is intended pri- conductance values on the plate char- marily for training radio technicians. acteristic curves. A knowledge of Ohm's This volume starts with job 51 and law and elementary math is needed. continues through job All The 75. are lab- method of design in straight- oratory type experiments which should forward and the necessary formulas are be combined with classroom instruction Powerful given. The first chapters discuss prin- to give the student a true picture of ciples and calculations pertaining to the servicing business. -LS FM RECEPTION - simpler circuits. Amplifiers, oscillators and detectors are covered later. Among 200 MILES PLUS! the design TRANSISTORS by Angelo C. Gillie. Pren- factors studied are dissipa- tice -Hall, Inc., Englewood Cliffs, N. J. New 6 and 12 element directional tion, bypass capacitance, load, stability, 6 x 9 in. 262 pp. $7.95. Winegard VAGI FM antennas. gain and distortion. IQ Use single bay or stacked This one is for beginner's. It starts for extra power. SOLID STATE MAGNETIC AND DIELEC- with linear and nonlinear conductors, TRIC DEVICES, edited by H. W. Katz. follows with diodes, then proceeds to Write today to: John Wiley & Sons, 440 Fourth Ave., New transistors. This order gets the student York, N. Y. 6 x 9 in. 542 pp. $13.50. off to a good start. The book stresses Most books on solid -state electronics theory, and the many schematics do Winegard Co. deal with transistors only. This one not list typical or practical component covers 3013 -8 Scotten, Burlington, Iowa everything but transistors. Some values. All explanations are physical, of the topics studied are: piezoelec- and math is avoided. The author uses 120 RADIO -ELECTRONICS

www.americanradiohistory.com BOOKS (Continued) simple equivalent networks to analyze transistor circuits. Each chapter includes worked -out Well -what about STEREO? examples and ends with questions and Answers appear at the end problems. tafad? of the book. One chapter is on point - Is Pot contact transistors. The final chapter it discusses rectifiers, thermistors, sur- can you convert face barriers and related devices. The 2 text is clearly written and is aided by many graphs and diagrams. -IQ started? What do you need to get by FM RADIO SERVICING HANDBOOK, 2 Gordon J. King. MacMillan Co., 60 Fifth records Ave., New York 11. N.Y. 9 x 6 in. 192 pp. about monaural $5. WhatW A theoretical and practical guide to FM radio including design, construc- What about multiplexing? tion, alignment and repair. Unfortu- nately for the US technician the book is written with a British slant, and the This new Gernsback Library book answers HOW TO SAVE $1.25 ON THIS DELUXE circuits and receivers used as examples HI -FI BOOK. are unfamiliar to the American reader. all your questions about this dramatic new phase of high fidelity. Written for the non- You can buy STEREO -How it Works -or Byron LAYMAN'S GUIDE TO HI -FI, by technical audiophile as well as for the fan any of the other handsome G/L High Electronics Co., 1203 Wels. American Fidelity books for only $3.75 -a saving of Bryant Ave.. New York 59, N.Y. 6 x 9 in. who keeps his nose in the chassis. Covers 25 % -by buying through the G/L Hi -9 76 pp. $1.25. basic fundamentals, stereo on discs, stereo This helpful little book for beginners Book Club. Build a complete hi -fi library on tapes, microphone techniques, ampli- contains a wealth of information care- one book at a time. No strain on the fully assembled and clearly written and fiers, speakers -and finally how to install budget. Look each book over in your own is relatively well illustrated. There are a stereo system. This beautifully bound home before you buy. Keep (and pay for) numerous minor errors which an expert book belongs on every hi -fi fan's bookshelf. only the books you want. would not have committed, and the book written in 1958, since was apparently JOIN NOW Select STEREO- How it Works or any one of these books stereo is almost entirely avoided. -CG - already published. ELECTRONIC COMMUNICATION, by DESIGNING AND BUILDING HI -FI FURNITURE lak. Answers all your questions abort Robert Shrader. McGraw -Hill Book Co. By Jeff Markel) the electronic aspects of a tape re- Inc., 330 W. 42 St., New York 36, N.Y. How to have a hi -fi system that looks as corder. What to look for when you buy 6 x 91/4 in. 937 pp. $13. good as it sounds. For the hi -fi fan -or -whatvarious types will and will not do. A comprehensive text that contains home craftsman. Covers everything MAINTAINING HI -FI EQUIPMENT -By everything the reader needs to know from what woods and tools to use to Joseph Marshall. Covers the specialized about electricity, electronics and radio finishing, retouching, repair - and techniques necessary to repair hi-fi FCC or commercial placement in the room for better ap- equipment. Includes acoustical and to pass amateur pearance- license examinations. Despite this, the better performance. mechanical as well as electronic faults. book is not a license manual. It is a text AUDIO MEASUREMENTS - By Norman H. UNDERSTANDING HI -FI CIRCUITS - By goes into all phases of communica- Crowhurst. Covers audio measurements Norman H. Crowhurst. Now have t've that from service shop to laboratory level. tions. Among its topics are current, system best suited to your tastes -ard Shows how to make tests, what instru- budget. Crowhurst tells you which voltage and resistance; alternating - ments to use, how to interpret results. basic transmitters; phase inverter is best, weighs fixed vs. current circuits; H. A. HARTLEY'S AUDIO DESIGN HANDBOOK self bias, triode vs. pentode, answers transistors; motors and generators; -This expert explains design principles hundreds of other questions. radio direction finders; radar; basic so the non -engineering hi -fi fan can BASIC AUDIO COURSE - By Donald C. communications law; amateur rules and design his own equipment. Hoefler. Explains everything about regulations. END -LS ELEMENTS OF TAPE RECORDER CIRCUITS - audio from the theory of sound to disc By Herman Burstein and Henry C. Pol- and tape recording techniques.

HOW TO JOIN THE G/L AUDIO-HI FI BOOK CLUB. Select one book from those listed on the coupon. SEND NO MONEY -we will send you the book on approval. If you like it send your remittance for the special club price of $3.75.

New books are released about every three months. You receive these automatically on the same no -risk plan. You may cancel any time after you have accepted four books -no time limit. MAIL THIS COUPON NOWomma °mIllmwm "'"1 .1.m.''..m'' Gernsback Library, Inc., Dept. 89H Stereo -How it Works Designing and Building Hi -Fi Furni-.;re 154 West 14th Street, New York 11, N. Y. Audio Measurements Enroll me in the G/L Audio Design Handbook Elements of Tape Recorder Circuits AUDIO -HI FI BOOK CLUB. Maintaining Hi -Fi Equipment Send me the book checked on approval. Understanding Hi -Fi Circuits (Please check one only) Basic Audio Course

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AUGUST, 19 5 9 121

www.americanradiohistory.com I SUMMER SALE Any or all of these catalogs, bulletins, or periodicals are available to you on request ON NEW ITEMS direct to the manufacturers, whose addresses are listed at the end of each item. Use your letter - head-do not use postcards. To facilitate identi- Round I 3" 0 to 15 KV Meter (FS = Ma.) fication, mention the issue and page of RADIO - $3.95 ELECTRONICS on which the item appears. [ITERATURI UNLESS OTHERWISE STATED, ALL ITEMS ARE Heinemann Circuit Brkr. Volts 230 or 115 AC. GRATIS. ALL LITERATURE OFFERS ARE Trips @ 10 or 20 Amps. New. _. $2.75 VOID _ AFTER SIX MONTHS. GE 115 VAC Relay (60 CPS) DPDT -Hvy. dty. will handle 10 Amps $3.75 Square D Hvy dty SPDT Antenna Switch. New orig. box. Insulators 21/2" High. 6" blade. $1.00 ea.; Ten @ $8.00 transistors. Includes supplements mailed GE Vacuum Switch Type GL -1521. SPOT. every 3 months. - Sylvania Electric (ART -13) _ $2.00 ea. /New Products, Inc., 1740 Broadway, New Hallicrafters SX -28. SX -28A replacement Power Xfmr. New $5.50 York 19, N. Y. $3. Available from Syl- TV AND AUTO RADIO CONTROLS. vania distributors. Ceramic Coil Form 2" diem. Approx. 34 turns Replacement Guide RGC -2 lists hun- 696; 10 /$5.00 dreds of volume, tone and other controls ECHORASER is explained in detail in Fenwal Thermometer Switch. Cap. 10 Amps @ 115V. (5 Amps @ 230V.) Norm. Closed, for 22,000 models of TV sets and auto a little 12 -page booklet. The unit reduces Opens @ Approx. 192° F. New $2.75 ea. radios. Includes an index, IRC Con - print -through on recorded tapes. -Audio RG -59/U Coax Cable (73 Ohms) centrikit and Mallory Sta -Loc equiv- Devices, Inc., 444 Madison Ave., New $4.00 /C Feet- $37.00/M Feet alents.- Howard W. Sams Co., 2205 E. York 22, N. Y. GLAS -LINE. Plastic Guy Wire - 46 St., Indianapolis 6, Ind. $1. $2.89/100 ft.; $17.34/600 ft. PANEL INSTRUMENTS catalog 59 -1 is SHIELDED TEST LEADS. 44" long, 2 alligator DIPOLES AND VAGIS, a reprint from an 8 -page listing of panel meters in- clips at one end, 2 tip jacks at other end. RADIO -ELECTRONICS of an article ex- 4 Braided metal outer conductor. Useful for sig. cluding the new -inch Unimeters. These ger., output testing, etc. Stock #3F35- 74C /LI. plaining the effects of stacking anten- are two -piece instruments which have ONLY: 514 nas. Polar diagrams are shown in this independent scales and movements, ar- RUSSELL ELECTRIC. HP Motor. 3450 RPM. 4 -page brochure -Scala Radio Co., 2814 ranged for instant matching. -Triplett 1.8 Amps. Continuous Duty. Operates on 115 Volts DC. 201/2 lbs. New, in original CARTONS. 19 St., San Fransisco 1p, Calif. Electrical Instrument Co., Bluffton, VERY SPECIAL PRICE, ONLY: $4.95 Ohio. RESISTORS AND CONTROLS are cov- Aluminum box 4 "x5 "x6 ". Ideal for mobile

gear, etc. Perf. holes for cooling . $3.00 ered in catalog No. 59. Also included are INFRA -RED AND OPTICAL GEAR is (Parts worth several times cost of unit) tab -mount controls and miniature series shown in catalog 594. Complete infra- Close -Out: TN75 factory -wired 75 Meter CW 57 precision pots. -Clarostat Mfg. Co., red sniperscopes and parts are cata- Xmfr. 50 Watts. $27.50. Sealed mfgr's ctn. Inc., Dover, N.H. Also available at Clar- loged. 96 pages, primarily listing tele- JRC 400 -12 Vocaline Transceivers in sealed factory ctns. Operates 115 VAC or I2VDC on ostat distributors. scopes, optical lenses, prisms.- Edmund Citizen's Band. $100.00 pair- W /Mike & An- Scientific Co., Barrington, N. J. tenna. AUTO RADIO SWITCHES for 60 mod- Sale on Pilot -Life Assy's. All New W /all els are shown in the supplement Auto AUDIO ACCESSORIES catalog AD -59 Hdware, less bulbs: Radio On -Off Switch Cross -Reference. Knurled Head with Adjustable Light type lists 16 pages of handy items used in (Red) 250 ea. -5 /$1.00 These are for pushbutton sets in 10 tape recording, phonograph playing and Red Plastic bullet head type, removable from makes of cars from the '40's to present. complete systems. Many of these have front 250 ea. -5 /$1.00 -Centralab Div. of Globe -Union, Inc., previously been available from other White Removable 3/4" Diam. Jewel. Bayonet type lite 35c ea.- 10/$3.00 900 E. Keefe Ave., Milwaukee, Wis. makers. Gathered here in one listing T -17 Mike. New. Special only $4.95 TUBE -TRANSISTOR HANDBOOK in- they include testing devices and main- Sprague 2 Mfd. @ 4,000 VDC Capacitor. cludes receiving, special -purpose and tenance supplies as well as cables, plugs New. $5.50 each (2 for $10.00) picture tubes. Complete EIA engineering and adapters. -Audiotex Mfg. Co., Div. REACTOR -CHOKE - 0,02 Hy. # 8.5 Amps. design data are given in the 700 pages of of G -C Textron, Inc., 3225 Exposition D.C.-Lo- Resistance -8%" x 63/4" x 63/4 ". Com- 18, pletely Enclosed. Original Cost Approximately this second volume.- CBS -Hytron, Dan- Place, Los Angeles Calif. $25.00-Brand New Raytheon $7.50 vers, Mass. Both volumes, $10. Supple- INERTIAL GUIDANCE is explained in Write for Spring- Summer 1959 "Green ment service, $3 for 2 years. Sheet" catalog. Loaded with bargains. 254 layman's language in a 16 -page booklet. Western Electric Amplifier. Uses four 6L6G's. PROFESSIONAL MICROPHONES. cata- Gyroscopes, computers and accelerome- Beautiful rugged construction. Made by WE log 120A, a 24 -page book giving full in- ters are related and simply discussed in Navy. 115 Volts @ 6G for US Operates from Is ? Cycles. Unused. Shipping weight: 165 lbs. formation and list prices on 8 micro- What Inertial Guidance -Sperry Very special $75.00 phones and accessories for broadcast and Gyroscope Co., Great Neck, N. Y. M3 Sniperscope w /20 KV Pwr Supply. Lab other high -quality applications.-Elec- 8 tested. Finest unit available today ....$120.00 RF SWEEP GENERATOR catalog -A tro- Voice, Inc., Buchanan, Mich. describes sweep generators, markers, I -177A Mutual Conductance Tube Tester. Lab tested $24.95 MICROWAVE TUBES can be chosen attenuators, filters and detectors for 4X150A @ $7.00/ 3828 @ $3.00/ 3E29 @ from this selection chart listing magne- precise measurement of frequency re- $6.00/ 829B @ $8.00/ 813 @ $8.50/ 826 klystrons sponse in the laboratory and on the pro- @ 60c/ 404A @ $7.00/ 6C21 @ $10.00/ trons, traveling -wave tubes, VR -157 @ 350/ RK72 @ 250/ 316A @ 200/ and others. Frequency range, power, duction line. -Telonic Industries, Inc., 833 @ $1.00. Write for free tube order noise figure and operating conditions are Beech Grove, mud. blanks. - shown. -G -E Power Tube Dept., Schen- PLUGS. JACKS BARRY CLIPS. ADAPTER, and HAM - TV 5, N. Y. ELECTRONICS ectady numerous other useful small service CORP. TUBE HQS. INDUSTRIAL PA SPEAKERS, microphone stands and parts are listed, pictured, and shown in HIGHEST QUALITY TOP BRAND NAMES ONLY described in catalog mechanical drawings on 40 pages of BOXED LOWEST SENSIBLE PRICES accessories are GUARANTEED 59A. This 6 -page bulletin concentrates Catalog No. 59.- Herman Smith Co. All prices F.O.B. N.Y.C. Specify method of shipment. All merchandisea insured and guaranteed for on horn projectors, paging speakers and Available at dealers. cost of mdse. only. Send n225c for 1959 green sheet. other units used in commercial PA Open Monday to Saturday -tome in and browse -we PRECISION INSTRUMENTS for labora- are Prince St. /BMT Station -Spring St. /IRT work. -Atlas Sound Corp., 1449 39 St., Station. 1 flight up- 20,000 sq. feet of values. Thou- tory use are shown and described in de- sands of unadvertised specials. Phone: WAlker 5 -7000. 18, N. Y. Brooklyn tail in Catalog 5.58. Bridges, Q- meters, ELECTRONICS TUBE AND TRANSISTOR MANUAL, 11th null detectors and megohmmeters are R edition, contains technical data on 1,000 among the over 20 types listed. -Freed BA RY St., 512 Broadway, Dept. RE -8. N.Y. 12, N.Y. receiving tubes, 250 special -purpose Transformer Co., 1718 Weirfield tubes, 265 picture tubes, 240 diodes and Brooklyn 27, N. Y. END 122 RADIO -ELECTRONICS

www.americanradiohistory.com SCHOOL DIRECTORY ADVERTISING INDEX REALIZE YOUR DREAM responsibil- Radio -Electronics does not assume Become a graduate Electronics Engineer. FREE ity for any errors appearing in the index below. Share rewards awaiting college amen . higher income, rapid advancement. Im- CAREER Aero I'ruduris l'o. 52 portant firms interview seniors here regu- Aireo Radio l'orp. 113 larly. ARilsl Radio ('el p. 53, Arkay Radio Kits ha' 116 BOOKLET Audio l'air 118 Electrical Engineer in 27 Months B.S. degree in Electrical (Electronics or Power B & K Manufacturing Co. 21 (la cry Electronics Corp. 122 major), Mechanical, Civil, Chemical, Aeronau- Bell Telephone Labs. 24 tical Engineering. In 36 Months a B.S. in Busi- Blonder 'tongue Labs. 18 ness Administration (General Business, Account- 11:5 Bogen I David) Co., Inc. ing, Motor Transport Management majors). For Brooks Radio & Television Corp. 111 55 earnest, capable students. Small classes. More Burroughs Corp. professional class hours. Mature students. Well - equipped labs. Modest costs. Veteran approved. CBS Electronics 26.11(2 Mar., -85 Year -round operation. Enter Sept., Jan., Capitol Radio Engineering Institute 82 G. McCarthy. Director Canton Studios 118 June. Write J. Century Electronics Co., Inc. '(8 -II)) Admissions, for Catalog and "Your ('hartes Engineering Co. 103 Career" Book. Cleveland Institute of Radio Electronics Il Cornell- Dubilier Electric Corp. 93 Coyne Electrical School 107, 115, 111

DeVl'y Technical Instlttlte 7 Dressnet 108 2489 College Ave. Angola, hid.

Electra -Sonic Labs, 116 Eli55 ro- Voice, Inc. Inside hack ('over Electronic Chemical Corp. 113 Electronic Instrument Co. (Eli'(II 28 Electronic Organ Arts 27, 24 ELECTRONICS Electronic Publishing Co., Inc. lls Erie Resistor Corp. 22 PREPARE FOR A GOOD JOB! BROADCAST ENGINEER Cetnsbach Library, Inc. 112, 121 17 AUTOMATION Grantham School of Electronics RADIO SERVICING to guide you TELEVISION SERVICING Heald Engineering College 100 BLACK & WHITE -COLOR to a Heath Co. 60 -67, (19 Hudson Specialties Co. 11:1 APPROVED FOR VETERANS AND SURVIVORS successful future OF VETERANS Indiana Technical College 118 BUILDING AIR CONDITIONED in International Business Machines (IBM) 104 -IOS SEND FOR FREE LITERATURE BALTIMORE TECHNICAL INSTITUTE Jensen Industries 115 1425 EUTAW PLACE, BALTIMORE 17. MD. ELECTRONICS Key Electronics Co. 114

Lafayette Radio 124 Lel:i ritti Inc. '16 ELECTRONICS Littelfuse, Inc. 117 rc for"P uttllm- ENGINEERING DEGREE COMPUTERS tuen 12 i 27 Mallory f l'.R.) & Co., Inc -13 wnitie.+tunnies IN MONTHS 1111 electronics! Merit (oil & Tr:utst nruier Corp. 8.S. Engineering degree (2] o.): Mathematics, Electric - Moss Elect runic lite. 72-73 -al Engineering, TV. advanced tiadlo Theory and Design. C AL B.E. (36 mo.): Aeronautical, Chemical, Civil, Electrical, :Mechanical, Metallurgical Eng. B.S. (38 mo.):.): Math., board. National Raclin Institute 3 Chem., Physics. Also preparatory courses. 211 bides., dorms. gym. Euter Sept., Nations) Schools G.I. approved. ENGIN ERING Dec.. March., June. Catalog. Keeping pace with progress. Newbury Engineering Co. 114 INDIANA TECHNICAL COLLEGE 1589 E. Washington Boulevard, Fort Wayne 2, Indiana 108 This interesting pictorial booklet Opportunity .\d l et s Oxford Components, Inc_ 118 tells you how you can prepare for a GET INTO dynamic career as an Electrical En- Paro Electronics Co., Inc. 111 Pickering & Co., inc. 117 gineer or Engineering Technician in Picture Tube I )tit let. 114 Progressive Edu- Kits Inc. 106 ELECTRONICS many exciting, growing fields: irMullin leads to success technicians, iield engineers, special- RESEARCH R- Columbia Products Co., Inc. Ils' ists In communications, guided mis- MISSILES RADAR RCA Electron 'rube Division siles, computers, radar and automation. Basic advanced courses In theory ELECTRICAL POWER ROCKETRY Institutes and laboratory. Assoc degree in elec- {radio Shack C, - tronics in 29 mos. B.S. in electronic AUTOMATÌON AVIONICS liamo Wooldridge engineering obtainable. ECI'D ac- Rinehart & Co., Inc. `i credited. G.I. approved. Graduates n SALES DEVELOPMENT !Rohn \lanufaet wring Co. 25 branches of tronics with mains companies. Start September, February. Dot s ci npns. High School graduate job or uivalent. :dug. Get all the facts about opportu- Sams (Howard W. ) & Co. , Inc. 0, 1111 16 Scott I I1. II.) Inc. VALPARAISO TECHNICAL nities, length of study, courses Service Instruments Corp. - --8, 96, 1)1)1, 113, 114, llli, 115 Sherwood Elect runic La bs., Inc. '4 INSTITUTE offered, degrees you can earn, Shure Brothers, Inc. 110 Dept. C Valparaiso, Indiana 75 scholarships, part -time work - as Sonotone Corp. Sprayberty Academy of Radio Television 10 well as pictures of the Milwaukee inc. 14 -15 Sylvania Electric Products School of Engineering's educational 118 Tarzian ( Sarlces I Inc. and recreational facilities. No obli- Trio Manufacturing Co. 119 Triplett Electrical Instrument Co. Inside Front Cover gation - it's yours free. Tung -Sol Electric Co. 20 Ile a "key" man. Learn how to scud Loudspeakers Inc. 108 and receive messages In International 4 University Morse code. Communicate with opera MILWAUKEE SCHOOL OF ENGINEERING tors around the globe. Learn at home Vis -U Products Co 117 quickly through famous Candler System. -all Used by best operators. Qualify for MAIL COUPON TODAY! Amateur or Commercial License. Write Westinghouse Electric Corp. 90-91 for FREE BOOK. MILWAUKEE SCHOOL OF ENGINEERING IVincga d Co. 120 CANDLER SYSTEM CO. Dpt. S.J. Box 0226, Denver 20, Colo. USA Dept. RE 859. 1025 N. Milwaukee St. Milwaukee, Wisconsin MS-113 acelite Inc. 115 Please send FREE "Your Career'. booklet SCHOOL DIRECTORY PAGE 123 ENGINEERING DEGREES I'm interested in Electronics Radio -TV Baltimore Technical Institute E.E. Computers Electrical Engineering Candler System Co. edan Electronics or Power Mechanical Engineering Mechanical, Civil & Physics Indiana Technical College Also in Liberal Arts & Business (PLEASE PRINT) Milwaukee School of Engineering Administration

College of Arts & Sciences , Earned through Pacific International Name... Age. Tri -State College HOME STUDY -' -- Valparaiso Technical Institute Resident Classes Also Desired Address BRANCH ADVERTISING OFFICES: Chicago: 5500 N. Available if Menard Are., Chicago, Ill., Spring 4 -1444. Los Angeles: PACIFIC PACIFIC INTERNATIONAL ARTS Harker- Dusted- Coughli,-., 600 South New Hampshire, Tel. INTERNATIONAL COLLEGE OF City_ ...... _...... Zone ...... State_.._....._..._ .... Hosted- Cough- DUnhirk 7- 2328. San Francisco: Harker- & SCIENCES benefits. 444 Mariai St., Tel. l:Artleld 1 -2481. Primarily a Correspondence I'm eligible for veterans education lin, School FOREIGN AGENTS: Great Britain: Atlas Publishing and 5719.M. Santa Monica Blvd., Discharge date...... _...... - ..._....._...... Distributing Co., Ltd., 18 Bride Lane, London E.C. 4. Hollywood 38, Calif. R. ------s--- =RaRrl.l.RaJ Printed in the United States of America AUGUST, 1959 123

www.americanradiohistory.com Df "aead., LAFAYETTE STEREO TUNER Use it as a Binaural-Stereophonic KIT FM -A91 tuner Use it as a Dual -Monaural FM -:1M tuner Use it as a straight Monaural FM or AM tuner

Multiplex Output for New Stereo FM 11 Tubes (including 4 dual -purpose) KT-500 IN KIT FORM + Tuning Eye + Selenium rectifier THE MOST Provide 17 Tube Performance 10KC Whistle Filter Pre -aligned IF's FLEXIBLE TUNER Tuned Cascade FM 12 Tuned Circuits Dual Cathode Follower Output EVER LT -SO COMPLETELY WIRED Separately Tuned FM and AM Sections 124.50 Armstrong DESIGNED Circuit with FM/ AFC and 12.43 Down -10.00 Monthly AFC Defeat Dual Double -Tuned Transformer Coupled Limiters. More than a year of research, planning and engineering went into the making of built -in ferrite loop antenna, less than 1% harmonic distortion, sensitivity of the Lafayette Stereo Tuner. Its unique flexibility permits the reception of binaural 5 microvolts, 8kc bandwidth and frequency response 20 -5000 cps ± 3 db. broadcasting (simultaneous transmission on both FM and AM), the independent The 5 controls of the KT -500 operation of both the FM and AM sections at the same time, and the ordinary are FM Volume, AM Volume, FM Tuning, AM Tuning and 5- position Function reception of either FM or AM. The AM and FM sections are separately Selector Switch. Tastefully styled with gold -brass escu- tuned, tcheon having dark maroon each with a separate 3 -gong tuning condenser, separate flywheel tuning background plus matching maroon knobs with gold and inserts. The Lafayette Stereo Tuner separate volume control for proper balancing when used for binaural programs. was designed with the builder in mind. Two separate printed circuit boards make Simplified accurate knife -edge tuning is provided by magic eye which operates construction and wiring simple, even for such a complex unit. Complete kit includes independently on FM and AM. Automatic frequency control "locks in" FM signal all parts and metal cover, a step -by- step instruction manual, schematic and permanently. Aside from its unique flexibility, this is, above all else, a quality pictorjal diagrams. Size is I33/Ar' W x 10n /s" D x 41/2" H. Shpg. wt.,.22lbs. high -fidelity tuner incorporating features found exclusively in the highest priced tuners. The new Lafayette Model KT -500 Stereo FM -AM Tuner is a companion piece to the Models KT -300 FM specifications include grounded -grid triode low noise Audio Control Center Kit and KT -400 70 -watt Basic Amplifier front end with triode Kit and the mixer, double -tuned dual limiters with Foster -Seeley "Triumvirate" of these 3 units form the heart of a top quality stereo discriminator, less than 1% hi -fi system. harmonic distortion, frequency response 20- 20,000 cps ± 1/2 db, full 200 bandwidth kc and sensitivity of 2 microvolts for 30 db quieting with full limiting at KT -500 Net 74.50 one microvolt, AM specifications include 3 stages of AVC, 10 kc whistle filter, LT -50 Same as above, completely factory wired and tested Net 124.50 NEW! LAFAYETTE PROFESSIONAL STEREO MASTER AUDIO CONTROL CENTER KT -600 79.50 IN KIT FORM The Lafayette KT -600 Solves Every 7.95 Down 8.00 Monthly Stereo /Monaural Control Problem!

RESPONSE S- 40,000 CPS ± 1 DB TAPE HEAD PLAYBACK EQUALIZATION LA -600 FOR NEW COMPLETELY WIRED 4 -TRACK STEREO 2.2 MILLIVOLTS SENSITIVITY FOR 1 VOLT OUT LESS THAN .03% IM 134.50 DISTORTION 6 CONCENTRIC FRONT PANEL CONTROLS 4 CONCENTRIC REAR PANEL INPUT LEVEL CONTROLS 180° ELECTRONIC PHASE REVERSAL A REVOLUTIONARY DEVELOPMENT UNIQUE STEREO 8 MONAURAL CONTROL CENTER FACILITIES! IN STEREO HIGH FIDELITY. Provides such unusual features as o Bridge Control, for variable cross -channel feed for elimination of "ping -pong" (exaggerated channel OUTSTANDING PERFORMANCE SUPERIORITY! separation) effects and for control of a 3d- channel output for 3- speaker stereo systems; the 3d- channel output also serves for converting stereo program material to high quality monaural for recording or to AMAZING NEW BRIDGE CIRCUITRY 8 CONTROL FOR 3d play a stereo program monaurally through a separate amplifier and speaker system. The KT-600 also has full input mixing of monaural program sources (such as tape recorder and phonograph, etc.), a CHANNEL OUTPUT FOR 3- SPEAKER STEREO SYSTEMS! special "null" stereo balancing and calibrating system (better than meters), 24 equalization positions per channel, 12 db per octave rumble VARIABLE CROSS- CHANNEL SIGNAL FEED ELIMINATES and scratch filters, and a loudness on -off switch. Has clutch -type dual concentric volume controls which operate independently for balancing or simultaneously as the "PING -PONG" EFFECTS! Master Level Control. Other features include channel reverse, 180' phase reversal, input level controls

at all inputs. Sensitivity is 2.2 millivolts for 1 volt PRECISE out. Dual low impedance outputs ( "plate fol- "NULL" BALANCING 8 CALIBRATING SYSTEM - lowers," 1300 ohms) are provided. Frequency response is 5-40,000 cps ± 1 db; less than .03% IM BETTER THAN METERS! distortion. Uses 7 new 7025 low -noise dual triodes. Size 14" o 41/2" x 103/4". Shpg, wt., 16 lbs. Complete with printed circuit board, modern -styling metal chassis and cage, profusely illustrated 24 EQUALIZATION POSITIONS PER CHANNEL! instructions, all necessary parts. LAFAYETTE KT -600 Stereo Preamplifier Kit Net 79.50 CLUTCH -TYPE DUAL VOLUME -BALANCE CONTROLS! LAFAYETTE LA -600 Stereo Preamplifier, Wired Net 134,50

NEW! LAFAYETTE STEREO /MONAURAL BASIC POWER AMPLIFIER KIT 36 -WATT STEREO AMPLIFIER 18 -WATTS 2 PRINTED CIRCUIT BOARDS FOR NEAT, EACH CHANNEL SIMPLIFIED WIRING ID EMPLOYS 4 NEW PREMIUM -TYPE 7189 RESPONSE BETTER THAN 35- 30,000 CPS OUTPUT TUBES i, DB AT 18 WATTS FOR OPTIONAL USE AS 36 -WATT LESS THAN 1% HARMONIC OR MONAURAL AMPLIFIER INJERMODULATION DISTORTION A superbly- performing basic stereo amplifier, in easy -to -build kit form to save you lots of money and let you get into stereo now of minimum expense! Dual inputs are provided, each with individual volume control, and the unit may be used with a stereo preamplifier, for 2 -18 watt stereo channels or, at the flick of a switch, as a fine 36 -watt monaural amplifier - or, if desired, it may be used as 2 separate monaural 18 -watt amplifiers! CONTROLS include 2 input volume controls, channel Reverse switch (AB -BA), Monaural - Stereo switch. DUAL OUTPUT IMPEDANCES are: 4, 8. 16 and 32 ohms (permitting parallel (monaural) operation of 2 speaker systems of up to 16 ohms. INPUT SENSITIVITY is 0.45 volts per channel for full output. TUBES are 2 -6AN8, 4.7189; GZ -34 rectifier. SIZE 9- 3/16 "d (10.9/16" with controls) x 51/2"h x 13,4 "w. Supplied complete with perforated metal cage, all necessary parts and detailed instructions. Shpg. wt., 22 lbs. Power Amplifier Net 47.50 ONLY 4,75 DOWN 47.50 KT -310 Stereo Kit 5.00 MONTHLY P.D. Bo. Sit JAMAICA 31. N.Y., 444. ez& Radio DEPT.) H -9 f CI Send LAFAYETTE Catalog 590 CUT OUT FREE AND PASTE Name LAFAYETTE Address RADIO ON POST 165 -08 Liberty Ave. JAMAICA 33; N.Y. PLEASE INCLUDE POSTAGE WITH ORDER CARD City Zone State

124 RADIO -ELECTRONICS

www.americanradiohistory.com HEAR PAGING Clearer... Easier SAVE MONEY, TOO!

advanced engineering assures CLEARER COVERAGE with FEWER SPEAKERS

...improves efficiency.. . reduces listener fatigue

Every installation further proves the efficiency, utility, and economy of E -V souñd projectors. Messages become easier to understand without listener fatigue. At the same time, you save cost by using fewer speakers for proper coverage of the listening area. Wherever paging is required, get the benefit of natural voice reproduction.

Choose the Type Designed to Meet Your Paging Needs WIDEST DISPERSION. Exclusive cm' dual -diffraction design* gives uniform, wide angle coverage at all frequencies ... no dead spots, no hot spots. Exclusive E -V compound horn reduces compression distortion to as low as 2% at full power -thus assuring minimum listener fatigue at any sound level. High efficiency performance cuts the need for costly high power amplifiers.

CONCENTRATED COVERAGE. E -V newly designed reentrant projector provides highest intelligibility at lowest cost where sound must be concentrated. Handles twice the power of conventional speakers, for greater penetration.

Model 847 25 -watt CDP. Has two coaxially- mounted horns working from opposite sides of a single diaphragm. Special edgewise -wound voice coil provides 18% greater efficiency. Wide -range response: 250 -10,000 cps. Sound pressure level: 114 db. Dispersion: 60° x 120 °. Imp.: 16 ohms. Inde- structible fiberglass horn. Size: 11 %," x 7°%,, x 10;4" deep. Net wt. 6'/, lbs. List Price, $46.33 Model 847 -45 CDP with 45 -ohm voice coil for intercom applications. List Price, $47.83

Model 844 30 -watt Reentrant. Diecast aluminum horn, with removable driver, and universal mounting bracket. Designed for easy servicing with field -replaceable voice coil. Wide -range response: 250 -10,000 cps. Dispersion: 90 °. Sound pressure level: 120 db. Imp.: 8 ohms. Sze: 9%" diam. x 8/," deep. Net wt. 5 lbs. 10 oz. List Price, $34.50 Model 844 -45 Reentrant with 45 -ohm voice coil for intercom use. List Price, $36.00

(Sound pressure level measured at 4 ft. on axis from 500 to 1500 cps with full rated input.)

E -V sound projectors are extra -rugged for long -life service indoors or outdoors. They are weatherproof, blastproof, splashproof. Actual comparison on the job proves their superiority. Design Patent 169,904 Write for Bulletin 258A to Dept. 89 -E

No Finer Choice than giewerol'eL®

Other Popular Models in the Complete E -V Line For large area sound reinforcement: Model 848 30 -watt CDP or Model 848LT 30 -watt Long -Throw CDP, at $75.00 list. For high -fidelity voice and music: the E -V Musicaster at $80.00 list. Remember too, you get even better sound when you choose an E -V high -fidelity professional microphone from today's most complete line.

ELECTRO -VOICE, INC. BUCHANAN, MICHIGAN 848 CDP ? ; Musicas-erwww.americanradiohistory.com i

This man needed a replacement picture tube for his TV set -and he wanted the best. So his TV technician installed an RCA Silverama -the premium picture tube made of all -new glass and all -new parts. It's the finest picture available today -just right for the customer who expects top quality and top performance. Sell RCA Silverama with the assurance that you're delivering a completely new tube -a premium product that can command a premium price and premium profits for you! * * { * * Is your customer budget minded? Offer him an RCA Monogram- factory -rebuilt by RCA to dependable quality standards. There's no finer rebuilt made -just right for the customer whose primary consideration is price. Sell RCA Monogram with assurance -your customers will get satisfactory performance -and you will have fewer call- backs. Remember... RCA picture tubes -warranted for one full year and fit virtually every make and model TV set. RCA picture tubes -backed by a brand name you can sell with confidence. RCA picture tubes -pre -sold by an extensive and continuing national advertising campaign. GET THE FULL DETAILS FROM YOUR AUTHORIZED RCA DISTRIBUTOR TODAY!

RADIO CORPORATION OF AMERICA ^IVY_j Electron Tube Division Harrison, N. J.