11:S HUGO GERNSBACK, 1. .11: 114I Editor
CUSTOM-BUILT. PROJECTION TELEVISERS
SEE TELEVISION SECTION
JAN
1 9 4 9
3O
u s ond CANADA LATEST IN RADIO ELECTRONICS - TELEVISION LOOK TO' L J FOR _V_ ° _ Y SERVICE REQUIREMENTS
ere - at prices you can afford - are ffve Laboratory Caliber Electronic Test Instruments that you need to insure efficient and profitable AM - FM - TV servicing.
MODEL 900 -A "VOMAX" The new " VOMAX" is the truly universal R tobte v.t.v.m. - makes TV, FM and AM measure- óeP ments accurately - at highest 'meter resistance. pOE`EEQe\e`t btees'vPsse`t M MS otPot 5 mc m Giant meter, non - breakable glass; 45 ranges; IE 216 `esc. ondnyote V tit9 tF 9"5°5/'3,1 \0 s999° 00e new single probe for a.c.. d.c.. a.f., r.f., volts, tha eP°tot ect\ototOnd o\t oske< shoPe ytne.vto íM50 oet ohms, Olt sis db. and current measurements. " VOMAX" ctysto\ cutyb0 so,w.oó\y sV \20P\t can be used for measuring TV power supply cóns\ ttss 0 potentials up to 30 svieeP Kilovolts when used with seeP our new High Voltage Adaptor Probe. Advanc- ing far beyond its predecessor, choice of experts, "VOMAX" equips you with the world's newest MODEL 906 and finest meter for only $68.50 net FM -AM SIGNAL Ch GENERATOR the big soi engineering P thousandsousa hen laboratories stands out as maximum 906 210 mc. in mum value. 8 ronges, 90 ky less accuracy; thanolt1/2 inc/ding microvolt, strays to ing; output; ver adjustable mu modulation, 0 e adjustable 0mplitud sweep 0 to 1,000 kc. ers ce onl M y $116.50 net. teyt ttgQ tal'' e A land Pod g05' et syni \.ttoc sn9\Y be QF. no mat VU m°O IA ss9 ss oc o1n WoH bssn9 p °,, am hs9h9 \ß" Cam eoker OS et. 9 tto`et tiC SP hOt e e0 c On 904 MAIL POST CARD sP 9''''''' s PM e sn net C/R for new o V\¡Pet 6 yes wsótosne$4q.50 kee t\.o t catalog showing complete A do\ condenser line of Laboratory Caliber `dept9 °ostotme5yé ceed\n9 coliber d ser re sistor Electronic Test Instruments. e tester pOeaO^e¢í v\oe \°t e* variable 9p5p,1s G dI0 oin_ ; 0 0/50% voltage oo9e y occur power OVER 37 YEARS OF RADIO EN e 1EERING ACHIEVEMENT factor. volts withws applied. 0/500 Mure ó Net
E X E T I C U V E F F I O C E S 1 2 4 0 MAIN ST., HARTFORD 3, CONN F A T C O R Y F F I 1 O C E 2 4 9 MAIN ST. HARTFORD 3, CONN 3 / Will Train You at, for Good Joy RADIO 4 TE LIVISIO N
I Send You Many Want a good -pay job in the fast -growing RADIO -TELEVISION Industry? Want a money- making Radio -Television shop of your own? Here's your opportunity. I've trained hundreds of men to be Radio Technicians . . . KITS OF PARTS MEN WITH NO PREVIOUS EXPERIENCE. My tested and proved train - at -home method makes learning easy. You learn Radio -Television principles for practical experience from illustrated lessons. You get practical experience building, testing, experimenting with MANY KITS OF PARTS I send. All equipment yours to keep. YOU BUILD THIS I TRAINED ,MODERN RADIO Make EXTRA MONEY In Spare Time THESE MEN The day you enroll, I start sending SPECIAL BOOK- MI LETS that show you how to make EXTRA MONEY bSvsTh1fi fixing neighbors' Radios in spare time. From here "Earned enough spare it's a short step to your own shop, or a good -pay time cash to Radio- Television servicing job. Or get into Police, pay for my Aviation, Marine Radio, Broadcasting, Radio Manu- course by or Public Address work. And think of get- time I grad- facturing uated. NRI training is ting in on the ground floor of the booming Television tops!" - ALEXANDER You build this complete, powerful Radio Re- Industry. Trained men are already in demand .. . KISH. Carteret, New ceiver that brings in local and distant sta- new stations are going on the air, manufacturers are Jersey. tions. NRI gives you ALL the Radio parts building over 100,000 sets a month, more and more 1st hn . speaker, tubes, chassis, transformer, homes are getting sets. The man who prepares now alla Ruskin sockets, loop antenna, etc. "Now have will reap rich rewards. two Radio YOU PRACTICE WITH SIGNAL GENERATOR shops servic- ing about 200 0\You i ui,,l this Signal Genera- ACTUAL sets amonth. ,. , tor for more E. Have largest valuable service establishment in expe- Southeast Missouri." * rience. It pro - MI LESSON ARLEY STUDYVIN.- vides ampli- Act now! Send for my DOUBLE FREE OFFER. Coupon DeSoto, Missouri. - entitles you tude modu- to actual lesson, "GETTING ACQUAINTED WI lá Is lated signals WITH RECEIVER SERVICING," absolutely free. Over SO Id i. SWlss dictums and diagrams ! You also get my 64-page book, for many tests "HOW TO BE A SPCCESS IN RADIO AND TELEVISION - "Am Chief and experiments. ELECTRONICS." Tells more Engineer of about YOUR opportunities, details Station of my Course, how quickly, easily WORD, in YOU USE TESTER you can get started. Send coupon charge of 4 In envelope or paste on penny men. Owe all TO EARN postal. J. E. SMITH, President, I know about Radio to NRI." -CLYDE BUR - EXTRA MONEY Dept. 9AX, National Radio Insti- J. tute, Pioneer Home Study Radio DETTE. Spartanburg, You build this South Carolina. Tester with School, Washington 9, D. C. parts NRI sends early in course. Soon help you fix neighbors' Radios and EARN EXTRA MONEY in spare time. MR. J. E. SMITH, President, Dept. 9AX YOU BUILD MANY OTHER CIRCUITS National Radio Institute, Washington 9, D. C. Practice FM experiments with Superhetero- '.lail me FREE Sample Lesson and 64 -page book about how to dyne Receiver Circuit . . . build Vacuum gin success in Radio and Television -Electronics. (No salesman Tube Power Pack ... practice locating de- will call. Please write plainly.) fects and repairing of still other circuits you Name.....___.- Age build with MANY KITS OF PARTS I send. GET THIS Address TRAINING UNDER S City Zone State..._..._ VETERAN G. I. BILL Check If Veteran Approved for Training Under G. I. Bill lb ,NO IV ow __ 4
Hugo Gernsback, Editor -in -Chief RADIO Fred Shunaman, Managing Editor M. Harvey Gernsback, Consulting Editor IRC Power Wire Wounds 11:111:47FILONICSu Robert F. Scott, W2PWG, Technical Editor R. H. Dorf, W2QMI, Associate Editor are better built formerly RADIO -CRAFT I. Queen, W2OUX, Editorial Associate Incorporating Angie Pascale, Production Monoger every step of the way SHORT WAVE CRAFT TELEVISION NEWS Elmer Fuller, Shortwave Editor RADIO A ISION Wm. Lyon McLaughlin, *Trademark registered U. S. Patent omee Tech, Illustration Director Starting right from G. Aliquo, Circulation Manager the winding form IRC Lamson, Advertising Director Power Wire Wounds John J. combine the best of Alfred Stern, Promotion Manager materials, workman- ship and resistor Contents January, 1949 "know -F ow ", Editorial (Page 21) Highest grade alloy Future Transistor Uses by Hugo Gernsback 21 wire uniformly wound Construction (Pages 22 -24) on sturdy ceramic Radio -Controlled Bus by M. Gordon Moses 22 tubes. Terminals spot welded for security; Broadcasting and Communications (Page 25) 25 heavily tin dipped for Rural FM Radio Network easy soldering. Television (Pages 26.30) Antennas for Television, Part I by Edward M. Noll and Matt Mandl 26 Climate -proof cement How to Get Television DX by Lyman E. Greenlee 28 coatingprovidesdark, Custom -Built Projection Televisers (Cover Feature) 30 rough surface -best for rapid heat dissipa- Theory and Design (Pages 31 -33, 85 -87) by Richard Henry 31 tion, moisture protec- Pocket Micro -Receiver tion and ability to Designing L -C Audio Filters by Richard H. Dorf 32 U.H.F. Noise Diode 85 withstand reasonable Multimeter Shows only Desired Scale 86 overloads. Problems of Electronic Baking 86 Resistors cured at FM (Pages 34-37) LOW temperature Visual FM Alignment by John B. Ledbetter 34 Conqueror) 36 prevents damage to Radio Set and Service Review (The Emerson resistance windings, Amateur (Pages 38-40) and loss of temper V.F.O. From Surplus by George F. Marts. WODTH 38 in terminals. Bands Wired Wireless Control Unit 40 for adjustable types Test Instruments (Pages 41-46) feature stainless Rodio- Frequency Ammeter by Rufus P. Turner, K6AI 41 steel springs and 'Scope Aid Helps Audio Men by Alfred Haas 42 silver contacts. Can- Tube Tester and Analyzer by Horold Pallatz 44 not corrode to cause Audio (Pages 47-48) high resistance. What is Supersonic Bias' by Dr. Angelo Montani 47 Foreign News (Page 49) European Report by Major Ralph W. Hallows 49 Servicing (Pages 50 -59) Improving Supply to Test Cor Sets by Harry S. Leeper 50 New York Servicemen Form State Federation 51 Jr Using Your Ohmmeter by Herbert S. Brier, W9EGA 52 The Impeded Double Cross by Guy Slaughter 54 For exacting, heavy -duty requirements you can rely on Electronics 71 IRC Power Wire Wounds for Midget Atom Smasher balanced performance in every full -sized, they Departments characteristic. Being 78 can operate continuously at full rating. The Radio Month 12 Question Box Derating in high ranges is unnecessary. Radio Business 18 People 79 New Devices 60 New Patents 81 IRC Power Wire Wounds are available Technotes 64 Radio -Electronic Circuits 84 in a full range of ratings, sizes and World -Wide Station List Miscellany 88 terminal types. 91 new ranges have by Elmer R. Fuller.... 68 Communications 93 just been added. Next time you step Try This One 76 Book Reviews 97 up to your distributor's counter - stock úp on IRC Power Wire Wounds. ON THE COVER: Assembly of a projection -type television kit. See page 30. Kodachrome by Avery Slack INTERNATIONAL Ave.. RADIO- ELECTRONICS, January. 1949. Volume XX, No. 4. Published monthly. PublicaHon Office: Erie 31. Pa. Entered as second elms matter September 27. 1948, at the post office at F to G Streets. Philadelphia 8. and Canada in U. S. Philadelphia, Pa.. under Uso Act of March S, 1879. SUBSCRIPTION RATES: In U. Central countries. two RESISTANCE CO. Allow one nientee oleaM30e.c Alt other $4.50 e. 8.005 for EtwoOyeare, $110Ö for three years. month for change of address. When ordering a change please furnish an address stencil impression from a recent wrapper. RADCRAFT PUBLICATIONS. INC. Hugo Gernsback, Pres.; M. Harvey Gernsback, Vice -Pms.; G. Allow, Seer. 401 N. Broad Street, Phila. 8, Pa. 1948, Publications, Inc. Text and illustrations must not be reproduced without Contenta Copyright, by Radcraft bt Canada: International Resistance Co., Ltd., EDITORIAL and ADVERTISING OFFICES. 25 West Broadway, New Tork 7. N. Y. Tel. REcor 2 -9890. BRANCH ADVERTISING OFFICES: Chicago: 308 W. Washington Street. Telephone RAndolph 8 -7363. Detroit; Frank Holstein. Toronto, licensee Room 402, Lexington Bldg.. 2970 West Grand Blvd. Telephone TRinity 5 -7026. La Angeles: Ralph W. Harker, 606 South Hill St. Tel. Tucker 1793. San Francisa: Ralph W. Harker. 582 Market St. Tel. Garfield 1 -2481. FOREIGN AGENTS: Great Britain: Atlas Publishing and Distributing Co.. Ltd.. 18 Bride Lane, Fleet St.. Lon YES! Were listed don E.C.9 Australia: McGill's Agency, 179 Elizabeth Street, Melbourne. France: Brentano's. 37 Avenue de l'Opera. Parle 2e. Holland: Trllectron, Heemeteedache, Dreef 124 Heemstede. G : International Book & News Agency, 17 in the RED BOOK Amorikia Street. Miter.. So. Atria; Central News Agency. Ltd.. CO, Risslk & Commissioner St.., Johannesburg' 112 Long Street, Capetnwn; 369 Smith Street, Durban, Natal. Universal Book Agency. 70 Harrison Street. Johannes Looking for the correct borg. Middle East: Stelmatzky Middle East Agency, Jaffa Road. Jerusalem. India: Scoli Gupta (Distributors) IRC replacement con- Co., Amite Baser Patrika Lt., 14 Allende Chatterlee Lane, Calcutta. trols for any receiver manufactured from MEMBER AUDIT BUREAU OF CIRCULATION 1938 to 1948? lust Editorial and Executive Offices: ABC PAID CIRCULATION 6 MONTHS TO JUNE 30. refer to the Radio 1945- 112,592. (Publishers Statement) PRINTED Industry RED BOOK! 25 West Broadway, New York 7, N. Y. FOR JANUARY ISSUE- 166,000 RADIO -ELECTRONICS for 5
TELEVI ON i (S
SHOP METHOD HOME TRAINING
Let NATIONAL SCHOOLS, of Los Angeles, a practical Technical Resident Trade School for almost 50 years, You rec vc all parts, eluding ubes, for bui train you for today's unlimited in Radio ing th!s 'ins, modern Su- opportunities Perhefercdyne Receiver lnis and other valuable standard equipment be property Comes your FREE 4°44 tiAe4z ry tea r4 ATEmammik. Good Jobs Await the Trained Radio Technician Los..,
You are needed in the great. modern Radio, Television and Electronics in- and dustry! Trained Radio technicians are in constant and growing demand Instruction at excellent pay -in Broadcasting, Communications. Television, Radar, Re- search Laboratories, Home Radio Service, etc. National Schools Master Material Are Up -to -date, Practical, Interesting Shop Method Home Study course, with newly added lessons and equipment, can train you in your spare time, right in your own home, for these excit- National Schools Master Shop Method Home Training gives you basic and ing opportunities. Our method has been by the remarkable success proved advanced instruction in phases of Radio, Television of National Schools -trained men all over the world. all and Electronics. Each lesson is made easy to understand by numerous illustrations and diagrams. All instruction material has been developed and tested in our own shops and laboratories, under the supervision of our own engineer You Learn by Building Equipment with and instructors. A free sample lesson is yours upon request-use the Standard Radio Parts We Send You coupon below.
Your National Schools Course includes You Get This and Other Valuable Both Home Study and not only basic theory, but practical training as well -you learn by doing. Resident Training We send you complete standard equip- Information in the Free Sample Lesson: ment of professional quality for build- Offered ing various experimental and test I. Basic Receiver Circuits and How They are units. You advance step by step until Used. you are able to build the modern su- 2. Construction of the Antenna Circuit. APPROVED FOR perheterodyne receiver shown above. 3. How Energy is Picked Up by the Aerial. which is yours to keep and enjoy. You perform more than 100 experiments 4. How Signal Currents are Converted Into Sound. build many types of circuits, signal- VETERANS generator, low power radio transmit- 5. How the Tuning Condenser Operates. ter, audio oscillator, and other units. 6. How the R -F Transformer Handles the Signal. Check Coupon Below The Free Books shown above tell you and other data. with diagrams and Illustrations. more about it -send for them today! NATIONAL SCHOOLS Now! NEW PROFESSIONAL MULTITESTER LOS ANGELES 37. CALIFORNIA EST.1905 INCLUDED: MAIL OPPORTUNITY COUPON FOR QUICK ACTION NATIONAL SCHOOLS. Dept. RC -I Paste on a postcard This versatile testing instrument is portable 4000 S. Fgurroa. Los Angeles 37. Calif. and complete with test leads and batteries. Simple to overate, accurate and dependable. Mail nie Fitg,R the books mentioned In Ymir ad Including a mutate lesson of You will be able to quickly locate trouble saur choice. I understand no salesman kill call on me. - and adjust the most delicate circuits. You can use the Multitester at home or on ser- vice calls. It is designed to measure AC and AGE DC volts, current, resistance and decibels. You will be proud to own and use this nURES' valuable professional instrument.
CITY Zoo STATE E DETAILS -SEND THE COUPON O Cheek here lt Veteran N World War tl
JANUARY, 1949 (i Opportunity Ahead but for TRAINED MEN Only!
CREI Practical Home Study Courses in PRACTICAL TELEVISION Can Help You Advance in this Expanding Field!
You can make your own opportunity in Television, if you start preparing now. No need to tell you how fast this great new field is expanding -or, of the great number of jobs that are being created. 1,000,000 Persons in TV If you are in Television now, expect to be, or wish to get in, CREI offers the very training you need to help accomplish your aims. Predicted Within 4 Years CREI can show you the way with convenient spare -time study at home that gives you the up -to -date technical background you must -by one of industry's leaders have for Television. CREI courses are designed to give you a thor- ough grounding in basic principles and take you step -by -step through the more advanced subjects of Television and its related By 1953: 12,000,000 TV sets fields. It must be remembered that all new electronic developments have their roots in past techniques. CREI training is basic and By 1953: 50,000,000 Audience helpful in your daily work right from the start. You will learn about and understand such subjects as: Optics; Pulse Techniques; Deflec- 40,000,000 TV tion Circuits; RF, IF, AF and Video Amplifiers; FM; Receiving By 1958: sets Antennas; Power Supplies; Cathode Ray, Iconoscope, Orthicon and By 1958: 100,000,000 Audience Projection Tubes; UHF Techniques, Television Test Equipment, etc. No matter how complete, or how limited your radio experience, CREI has a practical course of training for you based on twenty years CAPITOL RADIO ENGINEERING INSTITUTE 16th IL Park Rd., N.W. Dept. 141 -A, experience in training professional radiomen. The facts about Washington. D. C. CREI, our courses, and what we can do for you, are described in Mail me ONE FREE sample lesson and your 32 -page booklet. Your Future in the New World of Elec- our 32 -page booklet. It is well worth reading. Send for it now. tronics'. I am attaching a brief resume of my radio experience, education and present position. VETERANS! CREI TRAINING AVAILABLE UNDER THE "G. I." BILL! Check One Q PRACTICAL TELEVISION Course: PRACTICAL RADIO -ELECTRONICS Capitol Radio Engineering Institute NAME An Accredited Technical Institute STREET DEPT. 141 -A 16TH AND PARK ROAD, N. W., WASHINGTON 10, D. C. CITY ZONE. ..STATE I am entitled to training under the "C. I." Bill Branch Offices: New York (7): 170 Broadway San Francisco (2): 760 Market St. RADIO -ELECTRONICS for 7
MONEl Hj0 *OE trot NW'S EE READ TEI. ROW TO RADIO DIAGRAMS ARD SYMBOLS
r
I TRAIN YOU RIGHT BY SENDING YOU 8 BIG KITS OF RADIO EQUIPMENT INCLUDING A POWERFUL 6 TUBE SUPERHET RECEIVER AND 16 RANGE TEST METER! FRANK L. SPRAYBERRY Find out NOW how Spray - Soon after you start I send you my famous BUSINESS famous Radio teacher of hundreds berry Training prepares you BUILDERS that help you earn EXTRA CASH of successful Radio men. 1 for a Radio Service Business getting and doing neighborhood Radio Service jobs of your own - or a good pay while learning. You couldn't pick a better time to get Radio job. Just mail the coupon for a FREE Sample Lesson and my into Radio. The Radio Repair Business is booming! big FREE book, 'How To Make Money In Radio, Electronics, Tele- Good Radio Service and Repair Shops are needed every- vision." It tells how I train you at home during spare hours by put- where as millions of new sets are in use. Trained men ting you to work building, testing, repairing Radio equipment. The are wanted for opportunities in Police. Aviation and Sprayberry Course teaches you Radio by working with 8 big kits of Marine Radio, F. M. and Standard Broadcasting and Radio parts I supply. You build a powerful 6 tube superhet Radio, a 16-range test Television. Manufacturers are looking for men who meter, perform over 175 interesting, PRACTICAL experiments. My lessons are know Radio as production reaches new peaks. GET easy and interesting -you need no previous experience in Radio. Istart you at THE FACTS ABOUT YOUR FUTURE IN RADIO the beginning... and give you valuable "bench" experience that sticks with you. MAIL the COUPON TODAY for my FREE BOOKS' LEARN HOW TO BUILD -TEST- REPAIR RADIOS By Working with YOUR HANDS!
I give you a fine, mov- ing coil type Meter - with parts fora com- You ready learn Radio the PRAC- plete analyzer and Cir- You don't have to buy expensive You construct this recti- TICAL way ... when you build this cuit Continuity Tester. ready -made equipment. You get val- fier and filter, resistor and eon. big, powerful 6 -tube Superhet "Trouble- shoot" with uable experience building this Signal denser tester, and really get on Radio from parte I send you. professional accuracy. Generatorand Multi- purposeTester. the Practical end of Radio. STUDY AT HOME LOW COST RADIO TRAINING N SPARE Sprayberry Training costs surprisingly little! Easy monthly payments, if desired. Everything you need is furnished - nothing else to buy. With Sprayberry Training to back you up, you will be able to step RUSH COUPON %aa/ into your own profitable Radio Service Business or go on to a big opportunity in Radio, Electronics or SPRAYBERRY ACADEMY OF RADIO, Dept. 20.141 I Television. The I Trained Radio men can step into their men equipment send you is yours 'for SPRAYBERRY BUILDING, PUEBLO, COLORADO or Profitable Radio Seraire SAop keeps" - to use in your business or job. I have 20 NORTH WACKER DRIVE, CHICAGO 6, ILLINOIS trained hundreds of successful Radio men - and I can help you too. Get the facts about Sprayberry Please rush my FREE copies of "How To Make Money In I Training it's Radio, Electronics and Television" and "How To Read Radio - your first step to success, security will call. and a bigger income in a field where you'll really I Diagrams and Symbols." No salesman NOW! enjoy your work. Fill out and mail coupon TODAY. Two Locations I'll rush my two FREE books to you by return mail. IName Age Ì Approved for G. I. Training TO SERVE VETERANS.. under Public Laws 16 and 346. YOU I Address BETTER I Sprayberry Academy of Radio, Dept. 20N Mail Coupon To Location I City and Zone. State I Nearest Your Home Sprayberry Building 20 North Wacker Drive ' O CHECK HERE IF A VETERAN Pueblo, Colorado Chicago 6, Illinois (Mall In an Envelope or Paste on Penny Postcard) JANUARY. 1949 8
CREI Presents Just the
, Course You Need and Want to Safeguard Your Future -Earn More Money
'television and FM Servicing
Practical On- the -Job Training Program for the Receivers will be marketed in 1949. By 1951 two million TV units are expected to be flowing into American Better Serviceman Who Wants Greater Earn- homes. With Television comes FM receivers and circuits. ings and Security In This Expanding Field This new field demands a tremendous increase in the number of properly trained television and FM technicians THIS basic CREI Servicing Course paves the way to to install and service this equipment. greater earnings for you. Since 1927 thousands of professional radiomen have enrolled for our home study CREI EQUIPS YOU TO INSTALL AND SERVICE courses in Practical Radio Engineering. Now, CREI ALL TYPES OF TELEVISION AND FM RECEIVERS supplies the answer to the need for a Practical Servicing Now ... with the help of of the "top third" now en- Course. You do not have to be, or want to be, an this new CREI streamlined gaged in service work to engineer to benefit from this course. It is written for Service course you can move enter the ultimate profitable you -the average good serviceman! It's not too ele- ahead to unlimited oppor- field of television and FM mentary for the experienced. It's not `over the head" tunities in your chosen field. installation and service. CREI has again taken the This can be your big year! of those who have limited experience-if they have real lead by offering a course so Don't waste another day. ambition and natural ability. entirely new that for the first CREI has the answer to your time in our twenty-one year future security in this new CREI developed this course at the request of several history we can offer a down- servicing course. Write today large industrial organizations. The urgent need to-earth course of training for complete information. of for servicemen. In offering The cost is popular. The capable, trained servicemen is one of the big problems this course at a popular price, terms are easy. The infor- of the industry. Hundreds of thousands of Television CREI is enabling thousands mation is tree. Write today. Radio Service Division of CAPITOL RADIO ENGINEERING INSTITUTE
16th k Park Road, N. W., Dept.I51-A. Washington 10, 0. C. CAPITOL RADIO Gentlemen: Please send me complete details of your new home study course in Television and FM Servicing. I am attaching a brief resume ENGINEERING INSTITUTE of my experience, education and present position. NAME An Accredited Technical Institute STREET------Dept.151- A,16th & Park Rd., N. W., Wash. 10, D. C. CITY-..._--____ -.__ ZONE STATE I AM ENTITLED TO TRAINING UNDER G. I. BILL Branch n ires: New York (7) 170 Broadway an Francisco (2) 760 Market St. RADIO -ELECTRONICS for 9
VIDEO HAMS! SERVICE MEN! ALL TELEVISION ENTHUSIASTS! Teleäte II ere'S hr Thrill! PILOT CAN D D T-v PORTABLE TELEVISION
e": L.M!-.RWW10...1143._ 9950 Plus $1.55 Fed. Excise Tax
s ,._1-_tt s ll ^- - 3. T ` a. 7. 1
CANDID T-V OPTIONAL ACCESSORIES .+itho4t magnifying lens Magnifying lens (shown in illustration above) - 6 actually triplet picture area! $6.95 and $9.95 as s. a. , Leatherette carrying case (upper !cf.! with built -in telescopic steel antenna enables you to carry set everywhere $24.50
Imagine! Television at its very ;,nest -for less than $100! That's the PILOT CANDID T -V ... the newest national sensation! And -WHAT television! So clear. so bright -you couldn't buy a finer, sharper image if you paid TEN TIMES AS MUCH! So light, compact and handy (only 15 lbs!) you can easily carry it ANYWHERE ... to living room, radio shack, playroom, den, office. Per- fect for testing TV patterns on your regular service and installation calls. See and hear this sensational all- purpose television set at your nearest Pilot Radio dealer.
WRITE TO PILOT RADIO, Dept. RE, for name of nearest dealer. We will also send exciting details about new Pilot "Big Theatre" television console, featuring 16" x 12" viewing screen with famed Norelco "Protelgram" projection system.
PILOTRADIO CORPORATION, 37 -06 36th ST., LONG ISLAND CITY, N.Y.
JANUARY, 1949 10
SYLVANIA ADVERTISING HELPS SERVICE DEALERS INCREASE THEIR SERVICE BUSINESS!
whathat these u Read n am ai "Newspaper ads brought in over 100 dealers yoN radio sets for repair during July!" . f Dealer ll N and fa R' o.Pr Sdnertising Deportment yl vanle Elect Pa. "Gross business increased from Dear Sir; $90.00 to $135.00 per week" an w5 advertising o tell 1 nee helped you ho. my much your business. co-ordinated used and sntho I hase the radio spot postal cards, ot e the announcements window displays radio station. a They are taredatlarçe used at week range' eopl local people..at hou s nana! °on- sale I my living records, entire! so : through SYLVANIA'S FEBRUARY, MARCH AND usedv g service campaign ua bl ch helps end the business to mew Since increase per . hei lacreeeed have x to been using APRIL CAMPAIGN IS NOW READY paign fron na your per week gross. pr spendingeek $135.03 Myeuse 90 00 pense bo Before eoff cam- Here's what it contains: I have eveeege of $7.00 used ce rtelnly the o extra received For 1 a perfair the erereg ratura 3 Postal Card Mailings -one for each month. booklet. an very much 1 pleased with the s' 3 Window Displays -one for each month. radio spots lu your 3 Window Streamers -one for each month. 6 Newspaper Ad Mats -two sizes for each month. yyer.1-V'sátw> Rodio Spot Announcements - several for each month. r . SEND FOR FULL INFORMATION NOW! Sylvania Electric Products Inc. Remember, this campaign designed for your use ties up Advertising Department a directly with Sylvania's ad campaigns on national scale. Room R -1701 You pay only the postage on the government postal cards Emporium, Pa. you mail. Sylvania supplies everything else free! Mail coupon today! Gentlemen, Please send me full details on your February, March and April Service Dealer Campaigns. Nome SYLVAN 1.1 Company Address ELEC[RIC City Zone State RADIO TUBES; CATHODE RAT TUBES; ELECTRONIC DEVICES; FLUORESCENT EA MPS, FIXTURES, WIRIN G DEVICES; LIB HT BULBS: PHOTOLAMPS I J RADIO -ELECTRONICS for li Amazing New `ó 4WPAENT elps Prepare You FASTER, EASIER for .. . EL Ê _. M1711TKi Here's good news ... big news ... our BIGGEST NEWS in 17 years. The equipment pictured at left gives a partial idea of D.T.I.'s remarkable, new combination of shop- method training aids ... to prepare you AT HOME for your start in Television- Radio -Electronics. Get 48 -Page Book FREE' Mail coupon today for D.T.I.'s big new 48 -page OPPORTUNITY GUIDE BOOK. See how this amazing newer method helps you get started toward a GOOD /OB or your OWN BUSINESS in one of America's most prcmisirg, thrilling fields ... that includes Television . F.M., Train, 2 -Way Taxi, Aviation, and Broadcast Radio ... Industrial Electronics ... and other fast - developing branches. In addition to well -illustrated lessons, you work over 300 instructive experiments from 16 shipments of Radio -Electronic parts. Among these proj- you build and keep a -type RAY OSCILLOSCOPE ects commercial CATHODE OSCILLO. SCOPE . that helps you get practical Television circuit training. You also build and keep a double -range R -F SIGNALZENERATOR, a jewel- bearing MULTI -METER and a quality 6 -tube SUPERHET RADIO. MULTI - METER BUILD KEEP 300 MODERN CHICAGO You also use HOME MOVIES le LABORATORIES . . . a D.T.I. Exclusive! If you prefer, you can get ALL your prepara- D.T.I. alone includes the modern, tion in our new, Chi- . MOVIES cago training labora- visual training aid tories . one of the .. to help you learn faster, eas- finest of its kind. ier at home. You see electrons Ample instructors ... on the march and other fascinat- modern equipment ... Wrlto for details! ing "hidden action " -a remark- able home training advantage that speeds your progress. Mail a.ID You Get D.T.I.'s Effective - ti.; ]r EMPLOYMENT SERVICE When you complete your training, our effective Employment Service is avail- able to you without extra cost, to help R -F SIGNAL you get started. O.T.I. r.n,tEtlal , GENERATOR MAIL TODAY! 6 -TUBE RADIO MI11111111111111 RECEIVER DeForest's Training, Inc. 2533 N. Ashland Ave., Dept. RC-FI Chicago 14, Illinois Send me FREE your 48 -page OPPORTUNITY GUIDE BOOK showing how I may make my start in Television - Radio . DeFOREST'S TRAINING, INC. Electronics. CHICAGO, ILLINOIS II Name Age Affiliated with the De Vry Corporation Street Apt Builders of Electronic and Movie Equipment City Zone State. JANUARY, 1949 12 The Radio Month "SUICIDE ON WHEELS" was the of impulses -a different number for description given to TV receivers in each letter- actuates a magnetic tape autos by the National Safety Council recording corresponding to the letter so last month. "Keeping one's eye on the that the reader hears the letter pro- road ahead and on traffic behind and on nounced by the loudspeaker. both sides is the first essential of safe driving," a council statement said. The council said its staff would make a PREVENTIVE MAINTENANCE was further study of TV installations visi- the theme of a campaign carried out by ble to passengers only. radio repairmen of the Harrisburg, Pennsylvania, area during the month of November last. Sponsored by the Federation of Pennsylvania Radio Serv- icemen's Associations and put into ac- tion by the local Mid -State Radio Technicians Association, it stressed the advantages to the radio owner of hav- ing his set repaired before it breaks down, instead of after. The returns to the radio user, both in uninterrupted radio entertainment and lower repair bills, were emphasized in a month -long advertising campaign. Residents of the area were urged through the newspa- pers and over the air to bring their sets to their radio repairmen for preventive maintenance during the month of No- vember; a special check -over rate and guarantee was offered for that month Auto tele installation of Robert Wright of only. Milwaukee, which brought a shower of criti- National and local radio concerns cism from safety officers of several states. both cooperated with the Harrisburg BLIND persons may be enabled to read servicemen in the campaign. Large ordinary print by a new device demon- numbers of leaflets and display pieces strated for the first time last month by stressing preventive maintenance were RCA Laboratories. It is an advanced supplied by tube and set manufacturers. letter- recognition system on which Several local distributors, including much work was done during the war York Radio & Refrigeration Parts, the and at the suggestion of Dr. Vannevar D & H Distributing Co., the Radio Dis- O 1111M II TE Bush. tributing Co., and John Blessing & Co., A scanning device is moved along a alternated in running weekly ads fea- line of type. A miniature cathode -ray turing preventive maintenance in both tube explores each letter with eight morning and evening papers. These, spots of light arranged in a vertical with the Mid -State Association's weekly line. When a spot hits a black portion, ad, brought the campaign to public at- COMPOSITIONrin RESISTORS an impulse goes to a selector unit, where tention several days each week. All ads counted electrically. After featured the Code of Ethics of the As- You never have to guess about the resist- impulses are ance and wattage of any Little Devil resistor. each letter is scanned, the total number sociation (RADIO- CRAFT, March, 1948) Every unit is not only color -coded but indi- vidually marked for quick, positive identifi- cation. Millions used in critical war equip- ment. Standard RMA values from 10 ohms to 22 meggohms, in 34, 1, and 2 -watt sizes. Tol. ± 10%. Also ± 5% in 34 and 1 -watt sizes. Available Only Through OHMITE Distributors Ohmlte Manufa no Co. 4894 Flournoy St., Chicago, Ill. HMIITIE This device actually reads, pronouncing each letter as the photofube scanner moves over it. RADIO -ELECTRONICS for Tile Radio Month I13 ULTRAFAX. a new method for high- PRESIDENT -ELECT of the Institute speed transmission of pictorial or print- of Radio Engineers is Stuart L. Bailey, ed material, was demonstrated to the the IRE announced last month. Mr. public for the first time last month by Bailey is a partner in the firm of Jansky RCA. Feature of the demonstration was and Bailey, consulting engineers, as the sending in just two minutes and 21 well as a Fellow of the Institute. seconds of the complete text of "Gone With the Wind," the famous 1,047 -page novel. A picture of each page is transmitted via television to a TV receiver and is copied on microfilm. Thirty of these pictures per second are sent. A war- . developed system of high -speed photog- raphy delivers film ready for printing or projecting in 45 seconds. A TALKING STOVE is the property of Mrs. Walter Sechrist, of York, Pa. Mrs. Sechrist's gas range picks up the voice of a neighbor who is a ham. An engineer told her that two unlike metals in the stove are probably acting as an imperfect- contact detector. TELEVISION ANTENNAS within the sets are a major goal for research en- Stuart L. Bailey, new president of the IRE. gineers, said Dr. W. R. G. Baker last month. The General Electric vice- presi- Arthur S. McDonald, chief engineer dent pointed out that many people do of the Overseas Telecommunication not want to disfigure their homes with Commission, Sydney, Australia, was large antennas and that installation elected vice -president for 1949. costs are high. Eventually, he said, the engineers want to get the antennas NEW CO -AXIAL CABLE linking the right inside the sets, just as was done East with the Midwest will be ready for with standard radios. television use on January 12, the A. T. and T. Company announced last month. COLOR TELEVISION is the subject The eastern networks now link New of a patent granted last month to Dr. York, Boston, Philadelphia, Baltimore, Lee de Forest, pioneer radio inventor. Washington, and Richmond, with Pitts- The system uses a pair of cathode -ray burgh to be added shortly. The mid - tubes and a multi -color filter. Dr. de western cities joined by cable are Chi- Forest claims that the system elimi- cago, Cleveland, Toledo, Detroit, St. nates all color flicker. Louis, Buffalo, and Milwaukee. Two other cities are connected to networks by privately owned relays, Schenectady METAL -CERAMIC SEALING is and New Haven. All together, over 12.5 made possible by a new method devel- million families will be served by TV oped by General Electric, according to networks after January 12. an announcement last month by the is company's Dr. C. G. Suits. The seal FM PERMITEES who surrender their made by an alloy of silver and titanium. construction permits would not be al- The process will be especially valuable RCA, Commercial Engineering lowed to re -file for FM facilities within Section 49AW, Harrison, N. J. in making microwave vacuum tubes. two years after the surrender, accord- The sealing of glass and metal is now Send me the RCA publications checked ing to a regulation proposed to the FCC below. I am enclosing $ to cover commonplace, but glass presents diffi- last month by the FM Association. cost of those books for which there is culties due to heat in the u.h.f. regions. Many CP holders have "sat on" their a charge. Ceramic materials may now be used to grants and then surrendered them Name replace the glass. "without prejudice," waiting for other Title or Occupation operators to make FM a successful op- THREE TV ANTENNAS and an FM eration before spending money them- Address radiator may be placed atop the tower selves. This, according to Leonard H. City Zone State being constructed for Stromberg -Carl- Marks, FM Association's general coun- son's Rochester television station, sel, penalizes the conscientious broad- Oukk- Reference Chad, Miniature Tubes (Free). WHTM. The new tower will reach 1,005 caster who constructs his station and 1411-3 Tube Handbook (SI0.00)e. (B) RC-IS Receiving Tube Manual (35 cents). (C) feet above sea level and will be sturdy serves the public, even though he makes Receiving Tubes for AM, FM, and Television enough to support four additional an- no profit and may even sustain a loss. Broodaasl. (IO rent.). (D) Radlotron Designers Handbook ($1.25). (E) tennas. One will be used for FM sta- Quick Seledion Guide, Non -Receiving Types tion WHFM. has offered to of radio techni- (Free). (F) Stromberg TOWN MEETINGS Power and Gas Tubes for Radio and Industry share the tower with one other FM and cians will be held soon in Atlanta, (IO cents). (G) two more television broadcasters, since Georgia, and in Los Angeles, the Co- Pholotubes, Calhode-Ray and Special Types (IO cents). (H) the location of the tower is the best ordinating Committee announces. The RCA Preferred Types' List (Free). (I) available spot in the Rochester area. If Atlanta meeting is being held in the Headliners for Homs (Free). (J) the offer is accepted, the novel arrange- Municipal Auditorium January 31 and *Price applies to LI. S. and possessions only. ment will be the first in TV history. February 1 and 2. The Los Angeles L J Viewers will be able to beam their an- gathering will be at the Roger Young TIME MEN,' tennas to one spot and receive three Auditorium on February 28 and March RADIO CORPORATION of AMERICA of ghosts. 1 2. stations free and NANNiSON. N. J. JANUARY, 1949 14 ?"Iff: E HEATHKITS H E A T H K I T F M a n d T E L E V I S I O N SWEEP GENERATOR KIT A necessity for television and FM. This Heathkit completely covers the entire FM and TV bands 2 megacycles to 230 megacycles. The unit is 110V 60 cy power trans- former operated. Uses two 6J6 tubes, two 6C4 tubes and a 6X5 rectifier. An electronic swoop circuit is incorporated allowing a range of 0 to 10 MC. A sowtooth horizontal sweeping voilage and phase control ore provided for the oscilloscope. The coils are ready assembled and precision adjusted to exact frequency. As in all Heathkits, the best of parts are supplied, Mallory filter condenser, zero coef ceramic condensers, all punched and formed parts, grey crackle cabines, 5 tubes, test leads, etc. Better get il built new and be ready for the FM and TV business. Shipping wl. 6 lbs. 720t444, E L S E T O Vrieatlrleit B U Y . . SIGNAL GENERATOR KIT... earti/eu S I N E A N D $19.50 SQUARE WAVE ELSE TO BUY AUDIO GENERATOR Every shop needs a good signal g tor. The Heathkit fulfills every servicing need, fundamentals from 150 Kc to KIT $34.50 30 megacycles with strong harmonics over 100 megacycles covering the new television and FM bands. 110V 60 cycle The Ideal Instrument for checking audio ampli- transformer operated power supply. fiers, television response, distortion, etc Supplies excellent sine wave 20 cycles to 20,000 400 cycle audio available for modulation or audio testing. cycles and in addition supplies square wave Uses 6SN7 as RF oscillator and audio amplifier. Complete over same range. Extremely low distortion, less kit has every pari necessary and detailed blueprints and than 1 %, large calibrated dial, beautiful 2 instructions enable the builder to assemble it in a few hours. color panel, 1% precision calibrating resistors. Large easy to read calibration. Convenient size 9" x 6' x 4%" 110V 60 cycle power transformer, S tubes, detailed blueprints and instructions. R.C. type cir- Shipping weight 41/4 lbs. cuit with excellent stability. Shipping WI. 15 lbs. 71.0dew% ELSE TO BUY HE AT H K I T 110V A.C. MILITARY RECEIVER POWER SUPPLY KIT HEATHKIT HIGH FIDELITY Ideal way lo onvert military sets. 110V 60 c cy. transformer CONDENSER CHECKER KIT operated. Supplies 24 Volts for AMPLIFIER KIT filament -no wiring changos inside radio. Also supplies D.C. voltage Build this high fidelity 250V plate at 50- $195.0 - 60 MA. Connections direct to amplifier and save two- $1495 dynamotor input. Complete G thirds of the cost. 110V with all parts and detailed in- = 60 cy transformer oper- $5.95 structions. Shipping wt. 6 lbs. itoetegg .] ated. Push pull output T using 1619 tubes (mili- 110 V. A.C. TRANSMITTER POWER SUPPLY KIT ELSE BUY tary type 616's), two am- For BC -645, 223, 522, 274N's, plifier stages using o dual etc. Ideal for powering military Checks all typos of condensers, paper mica- triode (6517), as a phase transmitters. Supplies 500 to electrolytic-ceramic over a range of .00001 MFD inverter give this ampli 600 Volts at 150 to 200 MA to 1000 MFD. All on readable scales that ara read plate, 6.3 C.T. al 4 Amps, 6.3 at direct from the panel. NO CHARTS OR MULTI- fier a linear reproduction PLIERS NECESSARY. A condenser checker anyone equal lo amplifiers sell- 4 Amps. and 12V at 4 Amps. Can be combined to supply can read without a college education. A leakage ing for len times this price. Every part supplied; 3- 6 -9 -12 or 24 Volts at 4 lest and polarizing voltage of 20 to 500 volts pro- punched and formed chassis, transformers (including Amperes. Kit supplied complete vided. Measures power factor of electrolytic. be- quality output to 3 -8 ohm voice coil), tubos, controls, with husky 110V 60 cycle tween 0% and 50 %. 110V 60 cycle transformer operated complete with rectifier and magic and complete instructions. Add postage for 20 lbs. power transformer, 5U4 recti- eye fier, oil filled condensers, cased tubes, cabinet, calibrated panel, test leads and oll other parts. Clear detailed instructions for 12' PM Speakers for above 6.95 choke, punched chassis, and all assembly other parts, including detailed and use. Why guess at the quality and capacity of condenser when you can know for less thon a Mahogany Speaker Cabinet 14Yz' x 141/2' x 8' 8.75 instructions. Complete -nothing else to buy. Shipping WI. 22 lbs. twenty dollar bill. Shipping wt. 7 lbs. a . BENTON HARBOR 20, MICHIGAN RADIO -ELECTRONICS for 15 IDEAL 7E57 INSTRUMENTS HEATHKIT VACUUM TUBE VOLTMETER KIT Everything you want In o VTVM. Shatterproof solid plastic meter foce, automatic meter protection in burn -out proof circuit, push pull electronic voltmeter circuit assuring maxi- mum stability. Linear DC and AC scales. Complete selection of voltage ranges starting with 3 Volts full scale up to 1,000 Volts. Isolated DC lest prod for signal tracing and measurements of voltage while instrument is in operation. An ohmmeter section ac- curately measuring resistance of 1/10 ohm to one billion ohms with internal battery. ELSE TO Extremely high input resistance 11 megohms on all ranges DC and 6.5 megohms on AC. All these features and many more are the reasons hundreds of radio and television BUY! schools are using Healhkil VTVM's and recommending them to all students. Like all Heathkits, the VTVM kit is complete, 110V 60 cy power transformer, 500 microomp meter, tubes, grey crackle cabinet, panel, lest leads, 1% ceramic precision divider resis- tors and all other parts. Complete instruction manual. Better start your laboratory no and enjoy it all winter. Shipping WI. 8 lbs. $24Só HEATHKIT 3 ALL 2 HEATHKIT SIGNAL TRACER KIT -TUBE -WAVE INTERPHONE -WAY Reduces service time and greatly increaseseases 1 RADIO profits of any service shop. Uses crystal CALL SYSTEM KIT to follow signal from antenna to speaker. $8.75 Locates faults immediately. Internal amplifier An ideal way to Ideal call and savailable for speaker testing and internal learn radio. This otio peaker available for amplifier testing. Con- J kil is completer systenm or nection for VTVM on panel allows visual trac- ready to s homes, offices, ing and gain measurements. Also tests I Milt AC Operation ble, with tubes factories, stores, phonograph pickups, microphones, PA sys- and all other parts. Operates from AC. etc. Makes excel- tems, etc. Frequency range to 200 MC. Com- Simple, clear detailed instructions make lent $14.50 plete ready to assemble. 110V 60 cycle trans- this a good radio training course. baby welcchh er $195ó former operated. Supplied with 3 tubes, diode Covers regular broadcasts and short easy to assemble probe, 2 color panel, all other parts. Easy to wave bands. Plug -in coils. Regenerative with every part supplied including assemble, o detailed blueprints and instructions. uit. Operates loud speaker. Add simple instructions. Distance up to 1 5 Small portable 9' x 6' x 41/2'. Wt. 6 pounds. postage for 3 lbs. $8.75 mile. Operates from 110V A.C. 3 tubes, Ideal for taking on service calls. Complete HS 30 one master and one remote speaker. 7 a cs s e4 g 9 E L S E TO BUY Headphones per set $1.00 / your service shop with this instrument. 21/2'Permanent Magnet Loudspeaker1.95 Shipping WI. 5 lbs. ''eatllít ELECTRONIC SWITCH KIT D O U B L E S T H E U T I L I T Y O F A N Y S C O P E An electronic switch used with any o cillosope provides two separately controll- able traces on the screen. Each s trace is controlled independently and the position of the traces may be varied. The input and output traces of on amplifier may be observed one beside the other or one directly over the other illustrating perfectly any change occurring in the ampli- fier. Distortion -phase shift and other defects show up in- stantly. 110 Volt 60 cycle transformer operated. Uses 5 tubes (1 -6X5, 2- 6SN7's, 2- 6517's). Has indi. victual gain controls, positioning control, and coarse and fine sweeping rate control.. The cabinet and panel match o other Heathkits. Every port a plied including detailed in structions for ossembl y and use. Shippin g weight 11 lbs i?ew 1948 $3450 HEATHKIT 5" ELSE TO OSCILLOSCOPE KIT BUY A necessity for the newer rvicing technique in FM and television at a price e you can afford. The Heothkit is mplete, beautiful two color panel, all metal parts c punched, formed and plated and every part supplied. A pleasant evening's work and you have the most interesting piece of laboratory equip - m ent available. Check the features -large 5' 5BP1 tube, compen- sated vertical and horizontal amplifiers using 6517's, 15 cycle to 30 M cycle sweep generator using 884 gas ELSE TO BUY triode, 110V 60 . ..(le power transformer gives 1100 volts negative and 350 volts positive. Convenient size 81` x 13 high, 17' deep, weight It 26 pounds. $395,0 only All controls on front panel with test voltage and ext. syn. post. Complete with all tubes r..d detailed 4,,* 4) 35 today ORDER DIRECT FROM THIS AD. instructions. Shipping weight pounds. Oraer ,x-410-:44, while surplus tubes make the price possible. - 0- W E WILL SHIP C. O.D. .0 Add Postage for Weight Shown rite H E AILT H c. nits i ma ... BENTON HARBOR IO, MICHIGAN JANUARY, 1949 Lucy HEATH SURPLUS 11acu! A L L Q U A N T I T I E S L I M I T E D S U B J E C T T O PRIOR SALES BC 645 GENERAL ELECTRIC RCA NAVY COMMUNICATION RECEIVER APN /1 RADIO ALTIMETERS NO. 202. The last of these NO. 200. The last chance TRANSCEIVER beautiful RCA sets. Covers 195 to get a complete new 14 NO. 201. Complete Kc. to 9.1 Mc. continuously. tube rodio altimeter. Con- 15 tube transmitter - Supplied complete with tubes, tains 420 Mc. transmitter receiver. Ideal for control box, tuning unit, 24 and receiver, power sup - new citizens band Volt dynamotor, band change que-_ ply, range switches, two 460 Mc. for commu- motor, plugs and circuit dia- antennas, meter indicator, nication between of- gram. Superheterodyne circuit all plugs and instruction > fice and car, home, t covers aircraft, broadcast, short CI manual. This unit makes } boot, etc. Conver- wave, marine, foreign brood. excellent amateur station sion in August ELECTRONICS Maga- article È: casts. Has sharp or broad I.F.'s os it is right in the band. S zine. Brand new in original G.E. cartons B.F.O., etc. Shpg. Wt. 30 lbs. $29.50 Shipped in original ex- with tubes. Add postage for 25 lbs, `I $34.50 port crate. Weight 87lbs. erre _:.,:.:;; $19.50 ... 2 for $35.00 PE 125 TRANSMITTER G.E. BC 375 TUNING UNIT ACCESSORIES FOR BC 645 POWER SUPPLY NO. 203. Model TU1OB covers PE101C Dynamotor for NO. 223. Operates from 12 to use 10 Mc. to 12.5 Mc. New cam- g. car S 3.95 24 Volts and supplies 500 Volts with om mum cabinet. 3 110V 60 l Power Supply fi at 160 MA. Extremely rugged in tanks. i; The best buy of surplus. Over ,, for home or office use 514.50 construction used Army Complete with fuses relays S30.00 worth of new variable - """ - " "" "' - - condensers, coil, dials, switches, . for boats. T32 TABLE MICROPHONE $12.95 Shipping tW eight 73 lbs. etc. Add postage for 20 lbs. $2.49 : NO 210 One of th Army's be st. ideal G.E. 50 AMP CIRCUIT BREAKER FM PUSH BUTTON TUNER S callls stem, public a dress, amateur NO. New NO. 224. Brand new ten push but- 204. General Electric ' ose. Brand n n riginal cart ons. $ Army 6 50 Amp 220 Volt AC circuit ton tuning assembly from FM $2.95 Add postage for S lbs. 2.95 EACH- breakers. 100 Amp when used receiver. Contains 4 gang 100 MMF 3 FOR <: silver plated tuning conden- on 110V. Add postage for 4 lbs. :.! MINIATURE ELECTRIC MOTOR á2.50 ser. Add postage for 10 lbs. EACH NO. 211. Tiny Delco motor only 1" x $2.50 ;, BC 347 AIRCRAFT INTERPHONE lt4 "x2" 10,000 RPM. Operates from 6 RG 8/U FLEXIBLE to 24 V. Excellent for mod- AMPLIFIER ell. Add postage for 1 lb. COAXIAL CABLE ': NO. 205. Interphone amplifier con- 4' NO. 225. Standard television lead : tains 6F8 tube, Ouncer transformers, in 52 ohm. Any length up to 1,000 diagrams, etc. in aluminum cabinet. á'vó1.¡1 PER FOOT 'eft. Add for postage Add postage DYNAMOTOR NO. 212. Dynamotor only from ': for 4 lbs $2.95 N' PE 103 power supply. Input 6 or 12 POWER TRANSFORMER : x:. novv:v:rs:::e: GWIEVI 2000.-,,. D -OW Pi. OSSTHIPEC oR HOW TO ORDER e e e ASRHTOWNMNORORpDR°DEISNCOREIR TS1 W O . BENTON HARBOR 20, RADIO -ELECTRONICS for 17 ELECTRONIC BARGAINS Pz EXPERIMENTERS awd HOBBYISTS A L L Q U A N T I T I E S L I M I T E D S U B J E C T T O P R I O R S A L E S STANCOR FILAMENT TRANSFORMER BRAND NEW DM 64A 12 VOLT DYNAMOTOR NO. 242. Heavy duty Stanco, No. ARMY AIR FORCE NO. 269. Input 12V at 5 Amps. 57355 supplies 5V at 6 Amps, 5V at Output 275 Volt 150 MA. New. ij: ASTROGRAPH Shipping 3 Amps and 5V at 3 Amps $5.50 from 220V 60 Cy. primary NO. 259. The cose of 7 lbs. Each v.z or 1/2 above from 110V. this unit makes the DM 32A COMMAND SET DYNAMOTOR Cased type. Ship. i1 finest tool and service NO. 270. Part of 274N Command Re- R Wgt. 7 lbs. Each $ 1 .50 kit ever designed. Ply- ceivers. Input 28 Volts, output 250V G.E. THYRATRON TRANSFORMER 'E. wood construction, 14 x at 60 MA. Shipping $ NO. 243. New G.E. Transformer sup- 11 x 10" high, with 8 Wgt. 4 lbs. Each 5.50 plies 2.5V at .100 KVA, has 3KV in- covered compartments DM 21 12 VOLT DYNAMOTOR in the bottom for repair sulation 100V 60 cy. primary. Ship- NO. 271. Used in Army BC 312 E. parts, leather handle, ping Wgt. 13 lbs Communication Receiver. Input 12 F steel reinforced covers, 9 Each $9.50 Volts at 3.3 Amps. Output 235 '? hinged lid. Also - excel Volts at MA. New, RCA SATURABLE REACTOR TRANSFORMER lent as case for radio 90 original NO. 246. New RCA No. CRV30531 AC phonograph, move projector, cartons. Shipping Wgt. camera, shell ca fe, lbs. $5.50 current 750 MA DC current 2 Amperes. fishing kit, picnic kit, etc. The ostrograph itself, 8 Each Rated 1.75 henries. Ship- 'i (which cost the government $125.00) makes an PE94C SCR 522 POWER SUPPLY ping wgt. 4 lbs. Each $ 1 .00 excellent contact printer, and can be used for a NO. 272. Complete dynamotor 12.6V POWER TRANSFORMER foundation for enlarger, strip map' holder, etc. power supply for the SCR 522, oper- NO. 247. New cased 110 V 60 cy. The case alone worthn twice thet e ates from 28 Volts. Complete with Power Transformer. Supplies 440V Ct. price of $3.95 controls, filters, etc. Original car- at 60 MA, 6.3V at 2A. a d 12.6V at AN27 /ARN5 ANTENNA ton. Shipping Wgt. $O 1 Amp. Excellent for military sets. 34 lbs. Each Wght. NO. 260. Standard blind Shipping 7 landing antenna system. PEIO1C BC645 POWER SUPPLY 1 6 lbs. Each. $ .95 supply -. $9.50Brand new in original NO. 273. Complete power RCA INPUT TRANSFORMER crate. Ship. Wgt. 14 lbs. for BC 645. Operates from 12 or NO. 248. Heavy duty RCA No CRV- 24 Volts. Supplies both AC and DC 30529. Input has primaries 600 to 200 AS114 /APT ANTENNA SYSTEM required. Shipping $3.(75 and 25 ohms secondary Wgt. 13 lbs. Each _...- 250,000 ohms K C.T. Shipping Wgt. DM 35 12 VOLT DYNAMOTOR lbs. Each 1 2 $ .00 NO. 261. New blade NO. 274. New input 12 Volt at 18.7 REPLACEMENT POWER TRANSFORMER type antenna complete $7.50 Amperes. Supplies 675V at 275 MA with case assembly, t NO. 251. Excellent value or 1/2 above voltage from 6 volts. Ex- transform- in original carton. Shipping Wgt. ers made by one of largest trans- 9 lbs. cellent for auto use. Ship- former companies. 110V 60 cy. Pri- A5115 /APT ANTENNA SYSTEM ping Wgt. 11 lbs. Each . $7.50 mary supplies 746 V Ct. at 150 MA. PE 86 DYNAMOTOR 5V $7.50 }' at 4A and 6.3V at 4.5 Amps. NO. 214. A popular 28 Volt re- F Shipping Wgt. NO. 262. New blade type ceiver dynamotor used on present F 7 lbs. Each $2. i9 5 antenna complete with case military equipment. Supplies 250V FEDERAL POWER TRANSFORMER assembly, in original carton. Ship. Wgt. 11 lbs. at 60 MA. Shipping NO. 252. New cased 110V 60 cy. 4 lbs. Each $5.50 F. Power Transformer. Supplies 480V AT38A /APT RADAR ANTENNA CT NO. 263. New radar dome type an- GN 58 HAND GENERATOR at 50 MA and 6.3 V at 2.1 Amps. A NO. 275. Makes excellent home beautiful transformer. Ship- tenna with mounting base and con- nections, in original car- lighting plant, operated by wind .. ping Wgt. 4 lbs. Each 1 i propeller, waterfall, gas engine, or ton. Ship. Wgt. 11 lbs. $ 1 4.50 HEAVY DUTY 6 -12 -24 VOLT VIBRATOR hand crank. Reduction gear allows NO. 253. A husky vibrator ANIO4A BLADE ANTENNA full output at slow speed; supplies used on army transmitter. 1 NO. 264. Standard blade 6 volts at 2.45 amp., 425 volts ot Rated 30 amperes at 6 Volts $1.50.50 antenna used on many mili- .115 amp. New. Add 220 cycle with contacts for tary fighting planes with postage for 28 lbs. Each $7.95 connection at bate. 12 and 24 Volts, Synchronous coaxial Handles for GN 58. S .50 each type, has many industrial ap- Shipping Wgt. 3 lbs. Connecting cord for GN'58 plications. Ship. BENDIX MT51C TRANSMITTER CONTROL BOX with plugs CD1086 $1.50 each Wgt. 3 lbs. Each...... NO. 235. Contains channel switch, COLLINS AUTOTUNE CONTROL HEAD 4 CHANNEL emission switch, send NO. 278. Brand new ontrols used switch, power switch and indicators on the ART /13, 100 Watt, Trans- PUSH BUTTON TUNER for Bendieaaircraft trans- NO. 254. Permeability tuner from $5.50 mitter. Types 7, 8, 10, and 11 avail- misters. Ship. Wgt. 3 lbs. BC 728 containing RF, first detector, able. Get a spare while available new is over $22.00 and oscillator coils. Covers 2 to 5 MC. BC 6708 REMOTE CONTROL BOX as cost each. Complete circuit diagram furnished. NO. 265. Motor starting control Shipping Wgt. 3 lbs. Price any type Shipping Wgt. box has starting and stopping (mention when ordering). Each 2 lbs. Each $2.50 witch, indicator, cable and plug. $4.50 Wooden case. Ship. Si MC 432 VHF LOADING UNIT CONDENSER SPECIAL ANTENNA Wgt. 6 lbs. Each .957 279. Contains 2 pole, 5 position NO. 255. NO. An ideal oil filled power BK 22 RELAY ASSEMBLY rotary switchwitch with silver ceramic supply filter used in army 16 tube variable condensers, and coils for unit, has NO. 266. Used on SCR 269 2.5, 2.5 and 5 MFD all at matching VHF Transmitter to AN109 600V D.C. rating. Shipping Radio Compasses. Contains 7 stepping and control relays antenna with 50 ohm line. Many Wgt. 3 lbs. Each $ 1 .50 - junction box of aluminum. useful parts. Shipping Brand new. Ship. $3.95 Wgt. 2 lbs. Each $.50 TELEVISION CONDENSER Wgt. 7 lbs. Each 148 OUTDOOR TELEGRAPH KEY NO. 256. Aerovox Hyvol .05 MFD at HEINEMANN CIRCUIT BREAKER NO. 280. Rugged enclosed type 7500V. rating. Excellent television coup- NO. 267. Heavy duty type 7 Amp. for outdoor use, built for army ling condenser with mounting bracket. 24 Volt D.C. Many uses around to withstand hard useage. Com- Shipping Wgt. shop. Shipping plete with cord and P155 plug. 3 lbs. Each $3.50 Wgt. 2 lbs. Each $ 1 .00 Shipping Wgt. 2 lbs. Each $2.00 CUTLER HAMMER __.. BC 746 TUNING UNIT NO. 257. Plug in transmitter MOTOR FIELD CONTROL ONE KILOWATT ADJUSTABLE tuning unit from army Walkie NO. 285. Rated 10 ohms. 3.2 Amps. ANTENNA LOADING COIL Talkie. Contains antenna and Maximum. 6.2" diameter with knob NO. 282. Huge porcelain coil 4" tank coils, tuning condenser, and mounting feet, can be used to diameter 81/2" long, has 5 transmitting and receiving crys- regulate generator output voltage. sliders for adjustments. Ship- tals. Ideal transmitter founda- Shipping. Wgt. ping Wgt. 5 lbs. $3.50 tion. Shipping Wgt. 1 51bs. Each _._._.. $2.50 300 MA SELENIUM RECTIFIERS 1 lb. Each $ 1 .00 t PENN THERMO RELAY Rated 300 E NO. 209. MA at 36 (Same as above except trans- NO. 268. Thermo Relay with o a m - o Volts, complete with mounting matter crystalys in 80 meter e 45 to 10c complete `.! brackets. Shipping tour band $2.50 each) with 5 Fr.Ft. Oexible cable to im- Wgt. 1 Ib. - .,,..___.. 3 FOR $1.00 T30 THROAT MICROPHONE mersion bulb. Ship - NO. 258. Makes excellent contact -c= ping Wgt. 6 lbs $3.50 DUAL in SELENIUM RECTIFIER microphone for musical tru- B g IN 11 to 14 MC TANK COIL meat or vibration pick -up. Ship- NO. 283. Two units mounted on _ NO. 281. Plug in type used on ping Wgt. 1 lb. 51.00 each single bracket, each ection { BC 610 Transmitter. New, original Extension cord with for ' rated 15V. 01 1/z Amp. switch ( J cartons. Shipping Shipping above ' $ -50 each Wgt. 1 lb. Wgt. 2 lbs. Each $ .50 2 FOR $1.00 GIVE NUMBER POS HOW TO ORDER WEIGHT SHOWN. NO ORDERS UNDER 5400... WE WILL STAGE C.O D. JANUARY, 1949 181 Radio Business Stewart- Warner Corporation reports net Westinghouse Home Radio Division of ? earnings of $2,609,725, or $2.02 per Mansfield, Ohio, announces the produc- -WHY BUY OVERHEAD - share of capital stock, for the first nine tion of a new dual -speed record changer START 1949 THE "SENCO WAY" months of 1948. The statement was un- which will be able to play more than For low prices . for high Quality . . for Im- mediate service go the "Sonco Way "! Our policy of audited and subject to year -end adjust- four hours of record music. Either con- eliminating all unnecessary expenses enables us to pass along large savings to you. ments. In 1947, net earnings were $1,- ventional or long- playing Microgroove THOUSANDS OF TUBES! 938,851, or $1.49 a share, for the first records can be used. ALL BRAND NEW! R.M.A. GUARANTEE! three quarters. Immediate Delivery! Individually Cartoned! Lots of Lots of Sales for the first nine months of Emerson Radio & Phonograph Corpo- 10 10 1948 were $55,993,599, down 1.6% when ration of New York has just put on the Type Each Each Type Each Each priced OZ4 690 59e 6V5G 59e 490 compared to sales of $56,926,546 for the market the lowest- FM set. It 1A3 45 39 6V6GT /G 45 39 same period of last year. Sales for the will retail at $29.95. (See page 36.) 1C5GT 69 59 6W4GT 69 59 1D7G 69 59 6X5GT /G 49 39 third quarter of 1948 were $18,124,114, 1LC6 69 59 7A4 53 43 up 8.2% over 1947 third -quarter sales Tele -Video Corporation, Upper Darby, 1LD5 69 59 7A7 59 49 Pa., announces 1LH4 69 59 7B6 49 44 of $16,748,250. acquisition of two elec- 1LN5 69 59 788 69 59 tronic products manufacturing com- 105GT 55 49 7C5 55 49 panies as subsidiaries. They - 1R4 69 59 7F8 61 54 Hallicrafters Company of Chicago an- are Air 1R5 55 49 7.17 54 49 nounces that it will place on the market design, Inc. of Upper Darby, and Elec- 155 59 55 7N7 49 44 tronic Controls, Inc., East Orange, 1T4 69 55 797 69 59 an automobile television set. The set 1 U4 49 39 7X7(XXFM)44 35 will have a tamper -proof device which N. J. 1US 36 30 7Y4 44 35 IV 45 39 12A 79 69 automatically cuts off the power when 2A5 54 43 12A6 29 25 the car is in motion so that the driver Radio Corporation of America's consoli- 2A6 45 35 12A8GT 35 28 dated statement of income for the third 2A7 32 25 12AT6 50 45 will not be distracted from his job; 2X2/879 35 29 12A17 69 59 however, a second unit not affected by quarter of 1948 and the first nine 49 39 12AÚ6 65 55 months of the year, with comparative 387/1291 59 49 l28Á6 50 45 the shut -off device can be installed in 395 55 49 128E6 50 45 the back seat. figures for the corresponding periods of 354 55 45 12F5GT 35 27 1947, has been issued by GENERAL 3V4 79 69 12H6 39 34 DAVID SARNOFF, President 5U4G 50 40 12J5GT 25 19 Sentinel Radio Corporation of Evans- and Chair- 5W4GT 39 34 12J7GT 45 39 man of the Board of RCA. It included 5X4G 39 35 12K8Y 35 25 ton, Ill., has announced the manufac- earnings of subsidiaries. SY3G 42 37 12SA7GT /G 40 32 ture of a portable television set which 5Y3GT /G 40 33 125C7/1634 49 39 Total gross income from all sources 5Z4 59 49 125F5 T 40 32 can be from one room to an- carried amounted to $256,968,537 in the first 6A7 50 45 12SG7 55 45 other, to be plugged in wherever an a.c. 6ACS 69 59 125J7GT 55 49 nine months of 1948, compared with 6AC7/1852 65 60 125K7GT /G 45 35 outlet is available. 6A146 49 39 12517 49 43 $224,982,605 in the same period in 1947, 6AL5 49 38 125197 49 43 an increase of $31,985,932. 6AL7 69 59 12SQ7GT /G 40 32 The Radio Parts and Electronic Equip- 6ANS 65 55 125127 35 32 Net income, after all charges and 6A06 59 55 14A7 65 55 ment Conference and Show of 1949 will taxes, was $15,128,783 for the first nine 6A107 65 59 1486 59 49 be held at the Stevens Hotel, Chicago, 6A 6 49 39 19T8 89 79 months of 1948, compared with $12,- 6AÚ6 49 39 24A 49 39 from May 17 to 20. The Show is spon- 233,758 in 1947, an increase of $2,895; 6BA6 49 39 25Á6G 69 59 sored by the Association of Electronic 68E6 49 38 25L6GT 55 45 025. After payment of preferred divi- 6BG6G 99 B9 25Z5 49 45 Parts & Equipment Manufacturers, The dends, net earnings applicable to com- 6BH6 79 69 25Z6GT /G 45 39 Sales Managers Club (Eastern Divi- mon 68.16 59 49 26 32 25 stock for the first nine months of 6B7G 55 49 27 49 44 sion), The Radio Manufacturers Asso- 1948 were 92 ' per share, compared with 6C4 29 25 32L7GT 52 48 ciation, The West Coast Electronic Man- 71.1e per in the first nine months 6C5GT 40 35 35L6GT /G 45 39 share 6F6GT 45 39 35W4 43 40 ufacturers Association and The National of 1947. 6F7/VT70 39 29 3514 43 40 Electronic Distributors Association. 6H6GT /G 45 39 35Z5GT /G 43 39 6J5GT/G 45 39 35Z6G 43 39 Earnings of Admiral Corporation, Chi- 6J7GT 42 38 36 35 29 RCA Communications, Inc., New York, and its 6K6GT/G 45 39 42 47 41 cago, subsidiaries for the third 6K7 55 45 45Z5 59 49 announces that a new radiophoto cir- fiscal quarter ending September 30, 6K7G 50 41 46 59 49 cuit has been opened between Portugal 1948, hit an all -time high despite va- 6K7GT /G 49 39 50 1.49 99 6L5G 69 59 5085 42 32 and the United States. All types of pic- cation periods and steel shortages which 6N4 49 38 50L6GT 50 45 torial matter will be transmitted over were responsible for temporary shut- 6P5GT 5S 49 56 55 45 6R7GT 59 49 57 45 39 this circuit, linking New York and downs in several Admiral plants, ac- 657G 49 45 58 45 39 Lisbon. cording to Ross D. SIRACUSA, president. 6SA7GT /G 44 37 76 49 45 6587 55 45 77 35 27 Net sales for the third quarter totaled 65H7GT 40 32 78 49 39 Howard W. Sams & Company, Inc., In- $15,128,165, compared with $11,120,436 37 80 40 38 6SK7GT /G 49 39 81 1.49 99 dianapolis, Ind., publisher of Photo - for the corresponding period last year, 6SL7GT 49 47 82 69 59 fact folders, reports that the first an increase of 36 %. 6SN7GT 49 47 839 79 69 6507GT/G 44 37 84/6Z4 49 39 series of ten meetings on the West 6587 43 36 85 49 45 Coast, consisting of lectures on televi- Electronic Sound Engineering Company 6557 59 49 99V 35 25 6597 55 49 99X 35 25 sion installation and circuitry, has been of Chicago announces a Polyphonic 6T8 89 79 11717 52 48 held under the co- sponsorship of local Sound Store Broadcasting System, to 6U5/6G5 69 59 117Z6GT /G 89 76 6U6GT 40 29 1231 39 29 distributors of Photofact publications. be used in large stores, restaurants, in- 6U70 35 25 1644 29 19 Over 4,000 radio technicians regis- dustrial plants, bus stations, etc. A * * * * *,t * * * * * * * * * * * * * * ** Dividend of the Month! tered for these meetings to hear Mr. A. timer device automatically turns the set C. W. SAUNDERS of the staff of Howard on and off and increases or decreases TUNG SOL J.A.N. TYPE 39/44 & A series of lec- volume, to Individually Boxed. T ,-l.e adv..ntoge of this ter. W. Sams Company. the adjusting the output the rific saving now! ONLY 14C ea. 50 for $5.00 tures on the same subject will be held expected crowd at various hours. * * * * * * * * * * * * * * * * * * * * ** in all major centers of the country dur- OUTPUT [OL6 39e ea. TRANSFORMERS 6V6 PUSH PULL.. 49e ea. ing the fall and winter. The Solar Manufacturing Company, WRITE FOR OUR CATALOG! Paterson, N. J., has filed a petition in MINIMUM ORDER 51.00 Stromberg- Carlson Company of Roches- the United States District Court, to ORDERING-Send deposit for allVÇ.O.D. Shipments.EN UEei énto ter, N. Y., has announced price raises initiate proceedings under Chapter 11 refunded. Orden without portages be hippy d express collect. All prices F.O.B. illNew York City. on its radio and television receivers, to of the Bankruptcy Act. Reporting a take effect immediately. The increases deficit of $670,687 from its 1947 opera- range from $10 to $55. The company tions, the company proposes to submit 1 stated that the price adjustments re- a plan of debt arrangement with its Dept. D, 73 Wes+ Broadway sulted from increases in the cost of ma- creditors to make payment in full on a VNew York 7. N. Y. Tel. BEekman 3.6498 II terials and labor. deferred basis. RADIO -ELECTRONICS for 1!l NOW! the Famous 5S00 Photofeet PHOTOFACT TELEVISION TELEVISION COURSE in Book Form! COURSE Previously available only to Photofact subscribers -now pub- ;i1:74 lished to answer the insistent demand of the entire Radio Industry Now you can own the book that gives you NEW! 1948 Automatic a complete, clear understanding of modern TV principles, operation and practice. Pre- Record Changer Manual viously available only in PHOTOFACT Folder Sets, this superb course New Volume 2 covers 45 models made in 1948, has been bound in unified book form to meet an including new LP and dual -speed chang- overwhelming demand ers, plus leading Wire and Tape record- from radio men in every branch of the industry. Written in ers. It's easy to service record changers clear, easy -to- follow when you have the PHOTOFACT Record language, profusely illustrated, packed with valuable up- to -the- Changer Manual handy. Complete, accu- minute data. Covers on analysis of actual every phase of tele- rate data -based vision -gives you the groundwork you equipment. Gives full change cycle data, have to become must hints and a successful TV service tech- information on adjustments, nician. Bring your television knowledge kinks, complete parts lists, exclusive up-to-date this easy, "exploded" diagrams. Have this time- PHOTOFACT Television saving, money- making book in your Course is avail ble at your jobber - order your copy today! shop. Over 400 pages; de luxe Over 200 pages; fully illustrated; bound, 8'h x 11 ". Only ;675 sturdy binding, 8y= ;q 00 x 11 ". Only.. JJ 1947 EDITION. Volume 1, Automatic Record Changer Manual. A "Must" for Covers more than 40 different post -war changer models manufac- Everyone in Radio! tured up to 1948. Includes full hard -to -get data on leading Wire, Ribbon, Tape and Paper Disc Recorders. 400 pages; fully illus- liolspaowillPooeusioweeirmin trated; 8Vz x 11 ", hard cover. Only ;4.95 NEW! Specialized Photofact Volumes POST -WAR POST-WAR AUDIO COMMUNI- AMPLIFIERS CATIONS and RECEIVER Associated Equipment MANUAL This is the book that's wanted by New! Invaluable to Amateurs and NEW! Photofact Volume 5 custom -builders, audio men and Short Wave Listeners. Complete sound engineers. Covers a wide technical analysis of more than 50 Latest addition to the famous PHOTOFACT Volume variety of well -known audio am- of the most popular communica- series -brings your file of post -war receiver service plifiers and FM and AM tuners, tions sets on the market. An inval- data right up to December 1948! Most accurate and plus data on important wire and uable service aid, a perfect buying complete radio data ever published -preferred and tape recorders. Presents a complete guide for purchasers of communi- used daily by thousands of Radio Service Technicians. analysis of each unit. A "must' cations receivers. All data based Everything you need for faster, more profitable serv- for custom -installers and for sound on actual examination and study service specialists. 352 pages; fully of each unit. 264 pages; profusely icing. Order Volume 5 today -keep ahead with PHOTOFACT -the only Radio Service data illustrated; in sturdy bind- $395 illustrated; durably bound, $300 51839 ing, 81/2 x 11 ". Only 8'h x 11'. Only that meets all your needs! In deluxe Binder... Vol. 5. Models from July 1, 1948 to Dec. 1, 1948 Vol. 4. Models from Jan. 1, 1948 to July 1, 1948 Radio Industry Red Book Vol. 3. Models from July 1, 1947 to Jan. 1, 1948 The RED BOOK tells you in one volume what Vol. 2. Models from Jan. 1, 1947 to July 1, 1947 you need to know about replacement parts for Vol. 1. All post -war 1, approximately 17,000 sets made from 1938 models up to Jan. 1947 to 1948. Includes complete, accurate listings of all 9 major replacement components-not just one. Lists correct replacement parts made FREE Photofact Cumulative Index by 17 leading manufacturers -not just one. The easiest way to own the world's finest Covers original parts numbers, proper re- Radio Service Data is to subscribe regu- placement numbers and valuable installation larly to PHOTOFACT Folder Sets. Send notes on: Capacitors, Transformers. Controls, for the FREE Cumulative Index to PHOTO - IF's, Speakers, Vibrators, Phono -Cartridges. FACT Folders covcringallpost -war receiv- Plus -Tube and Dial Light data, and Battery ers up to the present. Helps you find the replacement data. 448 pages. 8' x 11". 5395 Folders you want in a jiffy. Get this FREE sewed binding. ONLY Index at your Jobber or write for it now. TUBE PLACEMENT GUIDE. Shows you exactly where to replace each tube in 5500 ORDER THESE BOOKS FROM YOUR LOCAL JOBBER radio models, covering 1938 to 1947 receivers. Each tube layout is illustrated by a clear, accurate diagram. Saves time -eliminates risky hit- and -miss methods. 192 pages; handy index. ONLY $1.25 DIAL CORD STRINGING GUIDE. The book that shows you the one right way to HOWARD W. SAMS & CO., INC. string a dial cord. Here, in one handy pocket -sized book, are all available dial cord diagrams covering over 2300 receivers, 1938 through 1946. Makes dial cord INDIANAPOLIS 7, INDIANA restringing jobs quick and simple. ONLY $1.00 JANUARY, 1949 20 Get Your FCC Ticket Which Jobs worth Better Pay $3,000 to $7,500 Do You Greater Security are opening up .l right now for A Nice Home T_ FCC Licensed Want? Happy Vacations Radiomen A New Car and Travel Add Technical Training to Your Practical Experience and Get Your FCC RADIOOPERATOR LICE 1 I SE in a few Short Weeks GET THIS AMAZING NEW BOOKLET It's EASY if you use CIRE Simplified Train :ng I. TELLS OF THOUSANDS OF BRAND -NEW, BETTERPAYING RADIO JOBS NOW OPEN TO FCC LICENSE HOLDERS. 2. TELLS HOW YOU WILL BENEFIT BY HOLDING AN FCC COM- and Coaching AT HOME in SPARE TIME MERCIAL LICENSE. 3.- TELLS HOW YOU CAN GET YOUR FCC COMMERCIAL RADIO OPERATOR LICENSE IN A FEW SHORT WEEKS- EASILY AND Get your license easily and quickly and QUICKLY, BY USING CIRE SIMPLIFIED TRAINING AND be ready for the $3000 to $7500 lobs COACHING AT HOME IN YOUR SPARE TIME. that are open to ticket is holders. CIRE training the only planned course of 4. TELLS OF HUNDREDS OF OUR SUCCESSFUL STUDENTS WHO coaching and training that leads directly to an FCC license. NOW HAVE LICENSES AND NEW, BETTER- PAYING JOBS. 5. TELLS HOW WE PREPARE YOU TO PASS THE NEW FCC COMMERCIAL LICENSE EXAMINATIONS, WHICH NOW YOUR FCC TICKET IS RECOGNIZED IN INCLUDE FM AND TELEVISION. ALL RADIO FIELDS AS PROOF OF 6. TELLS HOW WE GUARANTEE TO TRAIN AND COACH YOU UNTIL YOU GET YOUR LICENSE. YOUR TECHNICAL ABILITY. 7. TELLS HOW WE HELP YOU TO GET A BETTER -PAYING, LICENSED JOB, WITH OUR FREE AND EXCLUSIVE SERVICE, WHICH PREPARES AND MAILS YOUR EMPLOYMENT APPLI- CIRE Graduates Find CATION TO HUNDREDS OF EMPLOYERS, INCLUDING FM, AM AND TELEVISION BROADCAST STATIONS, RADIO FCC License Pays Off MANUFACTURERS, POLICE RADIO STATIONS, AND RADIO. EQUIPPED TAXI, BUS AND PUBLIC UTILITY COMPANIES. "Transmitter engineering is great, es- pecially in the job I am on. Thanks again for all you have done, and you can take credit for the fact that my "ticket" is now posted on the wall of a 1000 watt broadcast station." Student No. 3678N12 CLEVELAND INSTITUTE OF RADIO ELECTRONICS I DESK RE -I, 4900 Euclid Bldg., Cleveland 3, Ohio "I now hold ticket P -10 -3787, and hold- I ing the license has helped me to obtain (Address to Desk No. to avoid delay) the type of job I've always dreamed of having. I working I Yes, thanks fo CIRE, am now for CAA want to know how I can get my FCC ticket in a few short weeks by training as Radio Maintenance Technician, at a far bet- at home in spare time. Send me your FREE booklet "Money Making FCC ter salary than I've ever had before. I am License Information ", as well as a sample FCC -type exam and free booklet, deeply grateful." "How to Pass FCC License Examination ", (does not cover exams for Amateur I Student No- 3319NI2 License). "I was issued license P -2 -11188 on November 4. The next day I was signed Name on board a tanker as Radio Operator- Purser. Besides radio operating, I I handle the payrolls, etc., which is all over -time and brings my monthly pay up to between $500 and $650." Address Student No. 2355N12 I City CLEVELAND INSTITUTE OF RADIO ELECTRONICS Zone State Veterans check for enrollment information under G. I. Bill. I Desk RE -1, 4900 Euclid Building Cleveland 3, Ohio NO OBLIGATION -NO SALESMEN Approved for Training under "G.I. Bill of Rights" L a a a 11 RADIO -ELECTRONICS for Editorial 21 FUTURE TRANSISTOR USES Transistors will play an increasingly important role in the future . . . By HUGO GERNSBACK WHEN we look back upon the humble crystal de- it does not require the usual A- battery. For this reason many tector of the early radio days, long before the appliances -particularly those where space and weight are vacuum tube was invented, we must marvel at at a premium-will be the ones that come under immediate the spectacular comeback which it recently has consideration. These are chiefly hearing aids and vest pocket staged in the form of the new Transistor.* radio sets, both of which can now be made exceedingly small The crystal always was a fascinating device, the more -thanks to the Transistor. because clear and strong signals could be obtained without In a humorous -fanciful article in the April 1946 issue of either A on B batteries. This feature not only intrigued the RADIO- CRAFT, we predicted the "Radio Pen " -a radio set experimenter, but the technician and scientist as well. It so small that it would take the shape of a somewhat large is therefore not too surprising that the new Transistor fountain pen. Such a radio set is now no longer so fanciful. was evolved. A tremendous amount of work by the Bell Indeed, it would surprise us very much if one is not manu- Laboratory scientists went into its development. While the factured during the next few years. engineers have formulated a theory how the new device Pocket recording instruments whereby voice or sounds works, it is still too early to say just exactly what happens may be recorded in an instrument small enough to slip into and why it works as it does. The explanation is a highly your pocket also now become possible. technical one and we will not re-iew it here-simply for For military purposes the Transistor will assume new lack of space. proportions in equipping ground troops with small receiv- Those of our readers who are acquainted with some of ing instruments which weigh only a few ounces and there- our fanciful predictions -via our annual April Fool joke - fore do not encumber the soldier with extra weight. will remember the "Crystron Lapel Radio" in the April, 1947, Proximity fuses already much in evidence in World War issue, which closely parallels the Transistor in many II -where small radio sets were embodied in the nose of a respects. shell -can now be still further reduced in size and weight Like the Transistor the Crystron had a "grid." It too and be made much more efficient. It was the A- battery that used no A- battery, and in one instance a circuit was shown was particularly troublesome in World War II proximity which also disposed of the B- battery entirely -a completely fuses. batteryless amplifying crystal device. Another fanciful Every aviation pilot prays for the day when he will be diagram in the same article, labeled "A capacitive -grid able to get radar into his plane to safeguard him from crystal tube" probably came as close to the Transistor as dreaded collisions with other planes, mountains, and build- anything published up to that date. ing obstructions. Only the large size and great weight of These remarks are not made to detract from the great present radar installations are in the way. The Transistor work of the Bell engineers, but are made simply to show will certainly help to bring this achievement about in the that when many people think along identical lines some- near future. thing is bound to evolve. One of our pet peeves for a long time has been the cum- Inasmuch as the Transistor is an electronically operated bersome microphone which actors, singers and speakers device it would be interesting to know what happens, when use on the stage, in cabarets and halls. Such a microphone and if someone applies a radioactive -tipped cat -whisker to which pops from beneath the stage -or the type with the the Transistor,. as was suggested in the Crystron article in heavy base, that must be lugged around-is totally un- April 1947. necessary in this electronic age. These microphones con- Will this be the avenue to the abolition of the high -ten- stantly get in the actor's or speaker's way. If he steps sion B- battery voltage? It seems a foregone conclusion that away from the microphone the fading voice effect becomes at some time in the future the Transistor -or a similar grotesque. allied device -may be evolved in which no outside voltage In the future all this will be done away with. No longer will be required. will these unesthetic microphones be allowed on the stage or Many questions are asked by our readers about the floor. Instead, half of the entire public address system will Transistor -the most common being: Will the Transistor be carried by the actor or speaker. A concealed lapel micro- supplant the vacuum tube entirely? phone will be used, while a miniature radio transmitter Personally we doubt it. There are too many uses for the weighing but a few ounces will be in his pocket. Now he present -day vacuum tube and wherever power is required will be a walking broadcast station. A pick -up wire under- the Transistor may not be able to compete with the vacuum neath the stage or a metal strip underneath the rug or lino- tube. In high -power amplification, transmission, and many leum picks up the radio impulses and leads them to the other instances the vacuum tube is likely to be dominant public address system of the theater or hall. In this way the for many years to come. actor, speaker or singer will have free use of the hands with Yet, it seems certain today that the new and revolutionary no cumbersome microphone to hide the face. He can walk Transistor will supplant our present vacuum tube in many anywhere on the stage or podium-he is no longer chained instances. Its development is so recent that it is difficult to a fixed mike. He will speak in a normal voice which will to foresee all its many uses. From our present knowledge be broadcast from his pocket radio transmitter and sent out it should not be too difficult to make certain prognostica- over the public address system of the auditorium. tions based upon our knowledge of the radio art. These are just a few of the future uses of the Transistor. The Transistor is a radio and audio -frequency amplify- There are, of course, hundreds of others which will come ing device paralleling its forerunner, the electronic tube. about not only for personal use but also for the home, in It differs from the latter in a most important point in that the factory, in the stores, in the car -yes, and in television °See September, 1948. issue RADIO -CRAFT. to reduce the size of our television receivers, too. JANUARY, 1949 221 Construction FAEIO COFIROLEFID BUS By M. GORDON MOSES BUILDING radio -controlled models is perhaps the most fascinating, and certainly the most specialized, of model- making hobbies. Radio control is fairly commonly used by builders of model boats and airplanes, but it is seldom applied in model auto- push -pull oscillator, is small enough to contacts provide a continuous circuit to mobiles and similar vehicles. be held in the operator's hand. The re- the arms of the switch. The switch is This control system was developed ceiver, a superregenerator using an shown in the photographs and in Fig. 3. for use in a model bus, but can be ap- RK -61 with a 10,000 -ohm sensitive re- The outer ring and the inner circle of plied to almost any project where there lay in its plate circuit, is in the bus. contacts control colored indicator lights is sufficient space and where weight is The circuit is illustrated in Fig. 2. atop the bus so the operator can tell not an important factor. The control The heart of the control system is a the position of the switch arm. The in- system, installed in a model bus 22 special, motor -driven, 2- circuit, 12 -point ner ring and the outer circle of con- inches long and 9 inches high, enables selector switch. Its contacts are ar- tacts handle the various controls. it to perform many of the operations of ranged in concentric circles. The mov- The master control circuit is shown a full -size bus. The operator can start, able arms are on a piece of insulated in Fig. 4. When the transmitter key is stop, reverse, turn the vehicle right or material mounted on the shaft of the closed, the plate current of the RK -61 left, open and close the doors, operate motor. Concentric circles and wiping in the receiver decreases and the sen- the windshield wiper and stop signals, sitive relay RY1 closes the circuit to 3A 5 This and turn lights on and off -all by radio. 8 the power relay RY2. completes The vehicle was assembled from a the circuit to the selector motor, which kit, such as is available at most hobby continues to turn as long as the trans- shops, for a working -model bus. Seats mitting key is pressed. The operator and other interior fittings were left out knows the position of the rotating selec- to provide space for the control mech- tor switch by watching the lamp indi- anism. cators atop the bus. If the selector is stopped in the FORWARD position, sole- The Control Circuit noid SDI pulls the forward- reverse switch Si to the forward position, con- The control system consists basically 1áVA+ of a 6 -meter transmitter and receiver. $ +1 V 8- A necting the battery B2 to the driving The transmitter (Fig. 1), using a 3A5 Fig. I- Simple transmitter controls the bus. motor so that it propels the bus for - RADIO- ELECTRONICS for Construction I23 ward. The motor is connected to the turned to the right, the motor cir- rear axle with 1 to 1 gears. The bus cuit is closed through the axle and will continue to run forward until the contact A. Switch B closes the cir- selector is turned to REVERSE. cuit to the right -hand indicators. This Setting the selector at LIGHTS ON circuit is completed intermittently by causes solenoid SD3 to pull S2 toward the commutator and contacts E -E'. it, closing the circuit between the 3 -volt During a left -hand turn, the motor cir- battery, the headlights, and running cuit is completed through the axle and lights. When the selector is stopped at C and the indicator circuit through D. LIGHTS OFF, SD4 pulls S2 toward itself, The circuit is opened and closed by the opening the light circuit. To perform commutator and contacts G -G'. other operations with the lights on, al- Two operations are required to re- verse the bus: Set the selector to RE- vERSE. This causes SD2 to pull S1 toward it, reversing the connections between the driving motor and B2. In this position the circuit to the motor is completed through the auxiliary revers- A motor drives this special selector switch. DIRECTION OF MOTION SELECTOR ARM OUTER 12 POINT RING 1.5v 45V CONTACT WIPERS INNER 12 POINT RING Fig. 2 -The receiver is a superregenerator. POWER RELAY t low the selector to pass over LIGHTS OFF INNER CONTACT RING without stopping. This is possible be- CONTROL CIRCUIT cause the current to operate the sole- OUTER CONTACT RING noids is taken from BI through the INDICATOR LIGHT normally closed contacts on RY2. The doors are opened independently INDIC. LIGHT GATT by solenoids and closed by return springs when the selector is moved to INSULATED another position. When either door is SUPPORT opened, the return spring contacts two INDICATOR LIGHT BATTERY metal strips and closes the circuit to the INNER CONTACT RING AND OUTER 12 POINT RING TO POWER RELAY stop- and well -light circuits. The I CONTROL CIRCUIT lights go out when the doors close. The OUTER CONTACT RING AND INNER 12 POINT RING= LO VOLTAGE LO SPEED DC MOTOR SHAFT construction of the door- opening mech- I INDICATOR CIRCUIT anism and lighting circuit is shown in Figs. 5 and 6. A bell and buzzer simulating the Fig. 3 -This switch is the heart of the control system. View shows how it is constructed. "getting -off" signals that passengers give the driver are powered by a 3 -volt BN 02 22.5V + 22.5v11 - battery. The circuit is completed SELECTOR MOTOR through RY2 when the selector switch REV RY 1+ comes to rest on BELL or BUZZER. 4.5V The windshield wiper uses a solenoid 3V RY4 SD6, a return spring, and a thermo- 12 START (REVERSE, static switch S3 to provide a slow re- II REVERSE ciprocating action. Current from BI I FORWARD,!_ heats the bimetallic element, causing it 3LIGHTS OFF to bend and open the heating circuit 2 LIGHTS ON and close the circuit between the sole- 4 FRONT DOOR noid FRWRD and the battery. SD6 pulls the 50BUZZER windshield wiper in one direction. When SDI TO RCVR 6 ' EAR DOOR the cools, bimetallic element it again 7,43E11 closes the circuit to the heating element n and the BWINDSHIELD WIPER VIOLET spring returns the wiper to its 9 LEFT TURN normal position. The cycle WHITE n repeats as DRIVE 10 RIGHT TURN long as the is WIND- MOTOR selector set on RED SHIELD WIPER. + YELLOW n 3V Steering is controlled by a 22% -volt SOLENOID SLND motor geared to the front axle as shown 52 SD3 BUZZ n NI GREEN in Fig. 7. When the axle is turned ap- I- REAR DOOR n proximately 30 degrees to right or left, LIGHTS OF BLUE the steering motor is cut off by limit INDICATOR LAMPS VIOLET o switches, as shown in Figs. 7 and 4. FRONT DOOR S3 The wheels can be stopped in any inter- WHITE n mediate position by moving the selector n to a new position before the circuit is RED HEADLIGHTS AND opened by the limit The YELLOW n switches. cir- RIDING LIGHTS cuit is wired through RY3 so the motor GREEN o normally turns to the right. RY3 re- verses the circuit for a left turn. BLUE n Turn indicators are connected to SL ND 'SOLENOID blink when a turn is being made. LS. LIMIT SWITCH SM =STEERING MOTOR Fig. 8 shows the connections to the blinker circuit. When the wheels are Fig. 4 -The master control diagram. Other figures show the auxiliary actuating mechanisms. JANUARY, 1949 Construction 24 I ating solenoids are 11/2 inches long with diameter, spaced fo t/s inch, tap near canter, posi- tioned for best results). REAR STOP LIGHT enough wire added to give an over -all Model: I -kit for working -model bus; I- Lionel ther- FRONT DOOR REAR DOOR mostatic switch; I- buner, I -bell; 3 -271/2-volt d.c. FRONT SPRING REAR SPRING diameter of 1 inch. Those used to op- RETURN 5069600); I -271/2-volt motor CONTACTS CONTACTS. RETURN Motors (Delco type d.c. SPRING SPRING erate the windshield wiper, lights, and (Delco type 5068751); 12-3 -volt pilot lamps with reversing switch are % inch long and sockets; 12- "grain of wheat" lamps; sockets; mag- FRONT REAR net wire; spring brass; assorted tubing; incidental WELL WELL wound to an over -all diameter of sift hardware. LIGHT LIGHT inch. The cores are made of 1/16 -inch -3V soft iron rod. Steel machine screws are WHEEL BRASS AXLE WHEEL inserted in one end of the aluminum i Fig. 5-5 op- and well -light wiring layout. forms to adjust the pull of the solenoids. See Fig. 10 for construction details. The steering, driving, and selector I motors are 271/2-volt d.c. Alnico -field units rated at 250 r.p.m. The Delco type 5069600 driving motor runs at about 80 to 85 r.p.m. when loaded by BLINKER MOTOR the bus, which weighs about 91/2 pounds complete with batteries. The blinker motor is a Delco type 5068751, rated at WCD 271 volts d.c. and 10,000 r.p.m. This unit turns at about 300 r.p.m. with a REAR I MOTO REAR 3 -volt battery. Both motors are avail- able on the surplus market. 3V 3V The thermostatic switch is made by BRASS COMMUTATOR the Lionel Train Corp. for use with SEGMENT II~ D automatic crossing signals. COMMUTATOR WIPERS I N°26 BRASS WIRE ) INS = fON AXLE SIDE (TAPE) Construction projects such. as this INSULATION one can be undertaken by anyone, al- WCD =WOODEN COMMUTATOR DRUMS Lill- RTIL : LEFT AND RIGHT TURN INDICATOR LIGHTS though no radio -control system should be operated by anyone not holding an Fig. 8- Wiring of the turn- indicator circuit. amateur radio operator's license. A similar control system can be Fig. 6 -Door solenoid and lighting switch. worked out by wired remote control, and the operator can control the power CUTOUT ARM IN°IO/ STEEL WIRE I relay by inserting long flexible leads running to the operating, position. Closing the circuit to RY2 by wire will give the same results as radio control. FLRDM Bill of Materials Transmitter: 2 -4,700 -ohm, 1/2-watt resistors; 2- Fig. 9- Forward- Reverse switch and solenoids. .0001-µf, mica capacitors; I -3 -30 -µµf trimmer; I- u.h.f. choke or 35 turns No. 32 wire, close -wound on ADJUSTABLE STEEL SCREW- VARY 1/4-inch low -loss form; I -3A5; -meter tank coil AND I-6 I/16" RELUCTANCE PULL (5 turns No. 14 with Inside diameter, turns SOFT IRON spaced diameter of wire and center- tapped). 111//h7iiaiiiiiaiiiii 1. : ® Receiver: 2-3 -15 -µµf trimmers; I- 3.3.megehm, t .67 1/2-watt resistor; I- :0001 -µf mica capacitor; I -.05- i .µf, :150 -volt, - paper .capacitor; 1 -&,000 -ohm poten- TO MOTOR CIRCUIT BRASS TUBING tiometer; I- 10,000 -ohm relay (with normally open LIGHT WOOD/ 3/32" INSIDE DIA. ALUMINUM TUBING BRAZING contacts); I -RK -61 tube, I- u.h.f. choke or 35 turns COIL-RANDOM WOUN No. 32 wire,'close -wound on 1/4-inch form; 1-4-meter RONT AXLE tank coil (10 turns No. 14 wire with 1/2-inch inside Fig. 10-Construction of actuating solenoids. FLRDM= FRONT LEFT -RIGHT DRIVE MOTOR RCS= RIGHT CUTOUT SW LCS. LEFT CUTOUT SW WINDSHIELD BOTH SWITCHES SPRING BRASS WIPER SPRING 'TO GEARS" COMMUTATOR CUTOUT SWITCH WIPERS ARM A MOTOR FLASHER AXLE r COMMUTATOR DRUM N 22 PIANO WIRE oZ SPRING BRASS RK -61 SET SCREW TUBE Fig. 7- Special switches operated by axle. ing relay RY4. Moving the selector to REVERSE -START closes RY4 and completes the circuit to the motor. The bus is stopped by moving the selector to an intermediate position. LEFT -RIGHT DRIVE MOTOR The construction of the reversing lI switch Si can be seen in Fig. 9. LEFT -RIGHT Many of the problems of construction GEARS are left to the ingenuity of the individ- ual builder because of the particular problems of each project. Two types of solenoids were used in this model. Both LIGHTS ON -OFF SIGMA 8K., RELAY types are wound with No. 28 enameled SOLENOIDS ti magnet wire on 3/32 -inch inside diam- eter aluminum tubing. The door -oper- Top of the bus and indicator lamp leads are removed to show placement of the components. RADIO -ELECTRONICS for Broadcasting and Communications 25 Rural FM Radio Network FM chain serves farmers THE first cooperatively owned on the roof is the antenna (in circle) Farmers of other states are observing farmers' radio system in the world, which beams signals from the ST -link methods and results of RRN. the Rural Radio Network, serves transmitter (right photo) to the Ithaca 118,000 farms in upper New York transmitter, 9% miles away. All trans- State with programs, news, and reports mitters are 250 -watt units and resemble especially designed and timed for farm the one at bottom right. families. A large service area is desired, and The network consists of six FM sta- to that end the sponsors of the network tions, wholly owned by ten farm or- had a special receiver designed for ex- ganizations. Stations are linked only tra sensitivity. This was engineered by by radio. Sites for the transmitters North American Philips and is being were so ctosen that each station would distributed to the lis- be able to receive the next one's signals, teners by the co- in addition to providing the desired operatives whose local coverage. An affiliation with New members York Citys WGHF adds the facilities own the of a big -city outlet. broad- A mobile unit (above) originates pro- cast grams from rural spots. Main origina- sta- tion point for most programs is Ithaca; tions. a studio is shown below. In the control room is master- control equipment and RRN broadcasters originate programs in Ithaca studio (left), through the window of which Ithaca master control room can be seen. Sta- tion engineer tunes the ST -link transmitter (upper right). Parabolic microwave antenna (circle) beams programs to the main Ithaca trans- mitter, thence to listeners in area. All RRN transmitter plants resemble the one shown at lower right. A weather vane is atop the antenna. JANUARY, 1949 26 Tclevisimi Antennas for Television TELEVISION reception can be im- proved to a marked degree by cor- .<,i;;. ,i _. . x-.::. . rect installation of a well designed fi antenna. A good antenna system will do much to reduce snow effect, PART ghosts, poor contrast, and other picture defects which detract from the enjoy- ment of television programs. Most present TV aerials fail to take advantage of the high gain which can A simple and inexpensive way to be achieved by utilizing fully the prop- boost down erties of transmission lines and orien- signal input and eut tation and propagation characteristics. interference without using vac- This can be traced directly to the mis- information and contradictory theories uum tribes or altering antennas which daily confront the television re- pairman. To add to his confusion, his own experience with antennas seems to indicate that almost all he has been By EDWARD M. NOLL told is unreliable and cannot be de- pended upon to give predictable per- and formance. Too often he runs across in- MATT MANDL* stances where the same antennas and receivers in adjacent homes give far different results -yet one installation seems a duplicate of the other. Eventually the television technician and reflectors, to note what difference leads have a characteristic impedance comes to the conclusion that time con- each made in the received signal. of 300 ohms. sumed in trying to sort out all the con- Originally it was intended merely to A transmission line will transfer a flicting ideas on television antennas is give practical proof of accepted theory maximum amount of energy if it is ter- just wasted energy. In consequence he by considering all the factors which minated at each end in an impedance is firmly convinced that results are hap- might change reception under certain equal to Z.. A 300 -ohm line, for in- hazard and uncontrollable. He chooses conditions. The results and observa- stance, should be attached to a receiver an antenna which seems to give fairly tions, however, brought to light a num- whose impedance is 300 ohms. This line good results in most places, and makes ber of startling factors completely un- should also be attached to a 300 -ohm that model his standard installation. If known or ignored to date. Unorthodox antenna. This condition is approached results are below what they should be, methods for greatly increasing the re- with a folded dipole, which has a radia- he feels that it is a matter of locality ceived signal were evolved, and many tion resistance of about 292 ohms. (See and nothing can be done about it. pet theories long taken for granted diagram.) To clarify this situation, the authors were disproved. Theoretically, a maximum of energy undertook an exhaustive investigation Applied to typical installations, these will be transmitted to the receiver and of every typical television antenna in procedures improved reception to a re- the transmission line can be of any common use. Experimental antennas. markable degree -contrast increased, length- though line loss does increase arrays, and transmission lines were set interference and snow decreased, and with length (300 -ohm twin -lead has a up to affirm or disapprove existing fringe -area performance was brought loss of about 0.75 db per 100 feet). theories and ideas. Duplicate tests were to a level often comparable with that In actual practice, however, this ideal made in different localities, at both low of better reception regions. In many in- condition is rarely achieved, and cut- and high signal levels. Propagation and stances improvement was over 10 db ting the twin -lead to a random length terrain characteritics were checked to greater than that obtained with typical may result in a considerable decrease verify all findings fully. boosters. in signal strength. In order to under- Receivers with different input sys- To secure such results, changes must stand how this comes about and how to tems were also employed to get com- be made which differ radically from correct for it, a brief comparison be- plete data concerning their effects on what is normally encountered in typical tween the twin -lead (untuned) and a transmission lines and antenna sensi- home installations. Full benefits are ob- resonant line is necessary. tivity. Comparisons were made with tained only when consideration is given A resonant (tuned) line should be dipoles, folded dipoles, stacked arrays, to each item along the line -receiver, some multiple of a quarter- wavelength eTelevision Instructors-Technical Institute, transmission line, antenna, orientation, long. Such a line, when open -circuited Temple University and propagation characteristics. at one end, will not transmit or receive 292n Al ANTENNA TERMINALS For instance, the accepted theory any energy. Radio waves sent along it with regard to the popular twin -lead will be reflected back to create standing so much in use today is that this line waves. represents an untuned or nonresonant Standing waves on a transmission transmission characteristic. As will be line mean that there are voltage and seen, this concept must be modified. current peaks standing along it, with TV RCVR Such a line has a characteristic impe- a half -wavelength separation between Soon INPUT dance (Z,) which results from the size each peak. The ratio of these voltage of the two conductors, the spacing be- peaks to voltage nodes (low-voltage 300ATWINLEAD %MISSION LINE tween them, and the dielectric constant points) is the standing -wave ratio. These are theoretical impedance relationships. of the insulating material. Most twin- When such a line is a multiple of a RADIO- ELECTRONICS for Tcicrisiea 27 quarter -wavelength and is terminated been increased to a high level by ad- of either inductance or capacitance in its characteristic impedance, all of justment of the contrast control.) present in the line and will aid in the energy sent through it is utilized. On the lower channels the spacing bringing it back to a pure resistance. Under such an ideal condition there between high and low points along the As this condition is approached, there would be no reflected waves, and no lines will be correspondingly greater, will be a decided change in the picture standing waves. However, the farther due to the longer wavelength. However, on the viewing tube. the termination from the correct value, since some channels are harmonically Not only does the procedure mate- the greater the standing -wave ratio. related, an adjustment of this standing - rially aid picture signal, but it results The same holds true if the line is short- wave condition often results in improve- in a decrease of noise because an ap- er or longer than a multiple of a quar- ment for several channels. proach to a perfect balance will elim- ter- wavelength, since this will add ca- Several methods of minimizing stand- inate the possibility of stray pickup in pacitance or inductance to a line which ing waves result in a much better sig- either conductor. is supposed to be purely resistive. nal and a reduction of the snow effect The inability of twin -lead to act as a In television receiver installations on weak stations. Because the maximum truly nonresonant line is also caused by the preference is for untuned (non - results are realized when adjusting for the composition of the dielectric used. resonant) transmission lines because of a certain channel, it is best to correct Under tests in good signal areas, it was their simplicity. In such a line we for the weakest station. Thus, if chan- found that the line would pick up a shouldn't have to worry about length nel 10 is not received well, the twin -lead station even when disconnected from an and our only consideration would be a can be adjusted to favor this station and antenna and terminated in a 300 -ohm proper match at each end. If, however, bring its level up. resistor. With such a termination, no a mismatch occurs due to line charac- The procedures used to aid reception pickup should have been possible. When, teristics or incorrect termination, stand- are based on the fact that the line is however, it is properly cut and matched, ing waves develop. In such cases our actually resonant. When there are it still remains the most simple and twin -lead acts like a resonant line which standing waves on a transmission line, economical low -loss line for television is either improperly matched or not cut reflections along the line begin at the and FM reception. to the right length. When this happens, termination (television receiver input) In the next article co -axial cable will signal intensity is decreased enormously because the antenna acts as the gen- be discussed and comparison will be because much of the energy is reflected erator of the signal and the receiver as made with twin -lead. Gain considera- instead of being absorbed by the input the energy-consuming device. If all the tions will be analyzed and methods for system of the receiver. energy is not utilized by the receiver, improving signal strength given. be seen how im- some is sent back along the line to the (Amateurs and others who deal with Thus, it can readily with resultant are portant it is that the nonresonant twin - generator (antenna) transmitters familiar with the lead in the manner it should standing waves. If the line is not a power- wasting effects of standing act -that a -wavelength, not waves. is, like an untuned line having no stand- multiple of quarter However, most servicemen have ing waves. Actually, however, this is all the energy will be utilized. Remem- never met them before, professionally. never achieved when using any of the In view of the fact that twin -lead is standard types available at the present never non-resonant, the importance of time. Of the numerous installations the material in this article cannot be checked by the authors, it was found over -emphasized. that in every instance there definitely TheEditors, for example, were most were standing waves on the line. interested to note that a very snowy to be cut picture on channel 13 could be greatly If the line happened near improved merely by sliding the hand a multiple of a quarter -wavelength long was down a portion of the transmission line for a certain channel, reception until best picture point was found. fairly good and the standing-wave ratio Television installation and service ; still acted very much like low but it men might do well to carry with them a resonant line. several sections of line, each of a dif- A simple and quick method for check- ferent length, shorted at one end and ing the presence of standing waves is terminated in alligator clips at the to grasp the transmission line firmly at Grasp line and note whether picture changes. other. Clipping these, one at a time. to intervals of every 6 inches, with the the receiver would soon indicate what receiver tuned to some channel between ber that we are dealing with a resonant line, despite the fact that it was orig- stub length is optimum. A permanent 7 and 13. If the line has a high unbal- stub could then be cut.-Editor) ance, the picture will get dimmer when inally designed to be nonresonant. the hand is in some places and brighter The only way to match a resonant line happens to line is to make it a multiple of a quar- when in others. If the apparent be close to a multiple of a quarter - ter- wavelength- despite the wavelength, the results will not be so 300 -ohm match at receiver and antenna. pronounced will still be evident. Any one of several methods can be but utilized to tune the line for maximum If the contrast is decreased until the reception. A small variable capacitor picture is barely visible and the line is can be placed across the twin -lead at held with the hand at a place where it the antenna posts of the receiver, and results in signal increase, the difference the capacitance adjusted for maximum will be more noticeable, because on picture signal. Another method is to highly unbalanced lines it will bring keep cutting small sections from the the picture up to almost normal con- lead -in until the signal is at a maxi- trast. mum. The third, perhaps the most eco- method, This can be rechecked at high signal nomical and convenient consists of adding a section of twin -lead to the level. Advance the contrast control un- line. This is attached right to the an- til the picture is just on the verge of tenna posts of the receiver (see photo). tearing. Now grasp the twin -lead at a It is preferable to start with about place previously determined for signal 40 inches of line and cut off an inch or increase; the picture will tear, showing two at a time. Close the end of the line much greater signal input to the receiv- by twisting together a small section of er. (Excessive signal will tear the pic- the stranded conductors at the free end. ture if the gain of the i.f. stages has This shorted stub will nullify the effects A stub of the correct length tunes the line. JANUARY, 1949 :a1 Television HOW TO CET TELEVISION DX Experimenters in fringe areas are picking up satis- factory television programs with the help of multiple By LYMAN E. GREENLEE boosters, very high antennas, and careful adjustment AROUND Indianapolis, Indiana, All kinds of freak results can be ex- set owners are picking up TV pected in marginal areas -including programs from Chicago, about some good reception that would almost 190 airline miles away. Recep- lead you to believe the transmitter was tion is, at times, equal to that from about two blocks down the street. We Cincinnati's WLWT, approximately 90 have seen good, clear test patterns from miles distant. Both pictures and sound WLWT (Cincinnati) when the weather are being received; although frequently was very hot and there was not a cloud the picture comes in without the audio, in the sky-airline distance to the while at other times the video is lacking transmitter about 90 miles! Usually, but sound is perfect. Inability to re- however, results are better on a cloudy ceive both sight and sound simultane- day with relatively high humidity such ously is usually due to the narrow band as occurs either before or after a thun- width resulting from the use of pre - der shower. selectors or boosters in series. Most Most marginal installations are made marginal installations are using two or in homes of people who know quite a three boosters in cascade to build up the lot about radio or electronics-ama - gain sufficiently to swing the video end teurs, servicemen, engineers, and so on of the receiver. Consequently, the band -but a surprising number of sets are width is often narrowed to the point being installed for professional people, where either the picture or the sound such as doctors and lawyers. A few may be lost. Considerable care in peak- taverns have installed projection TV, ing the boosters is necessary to avoid even though the nearest transmitter is this difficulty, but it cannot be alto- beyond the normal range of satisfactory gether avoided in marginal installa- reception. Since it has been the policy tions. One very good solution for the of set manufacturers in general to dis- This Workshop Associates array, 90 feet in trouble is to use a separate receiver for courage marginal TV installations, the air, is the antenna of Elmer Taf linger. the audio. most of the sets have been privately installed by their owners. Maintenance How good is reception? has been left entirely to the owners, and TV set owners in the Indianapolis the manufacturer or distributor as- area are also reporting reception of sumes no responsibility whatever for signals from Milwaukee, St Louis, the results. Cleveland, and Detroit. There is often Are owners satisfied with their sets a lot of interference between stations and with the reception they have been on the same channel. Such interference getting? The answer, surprisingly, is a is particularly bad between WLWT at very definite "yes." A few owners did Cincinnati and WBKB at Chicago, both not know what to expect, and they have stations being on channel 4. There are been very much disappointed. They are times when you get the picture from the ones who were expecting to get pic- one transmitter and the audio from the tures like home movies, something that other. At other times both pictures mix just can't be done yet, at least not in together to form a garbled mess; marginal areas. Not all locations will and, as reception conditions vary, the give satisfactory reception, and an stronger signal is the one that pre- owner who installs a TV set in a par- dominates. Frequently we have seen a ticularly bad location may never be able program suddenly shift from one sta- to pick up a recognizable test pattern. tion to the other with no adjustment of Would -be televiewers must be warned the controls on the TV receiver. Reflec- of possible complete failure, or unsuc- tions from shifting cloud banks are par- cessful installations will create bad will ticularly annoying and are probably toward the installer. responsible for such freak effects. They vary in direction and intensity from Which is the best set? day to day and hour to hour. It is vir- The question is often asked: "What tually impossible to eliminate entirely type or brand of television receiver this type of interference. Rotation of should I purchase to get reasonably the antenna is probably the best and good reception in areas like this one, most effective remedy. Often a stronger far from television broadcast stations ?" signal can be picked up by tuning to a Any of the standard receivers now reflection, but it is likely to be very on the market will work in marginal Multiple boosting is necessary for reception. erratic and difficult to hold. areas if properly installed. Several kit RADIO- ELECTRONICS for Televisimi 129 receivers have been as successful as mize unwanted pickup and at the same standard makes. There is some differ- time put the maximum signal into the ence in stability and performance be- TV receiver. tween various sets; but, generally Get the antenna up as high as pos- speaking, no special set is required for sible. preferably on a utility pole that a marginal installation. Regardless of is climbable or on a good pipe or fabri- the type of set or make -selected, it is cated mast that can be lowered for re- very important to check it carefully (or pairs and adjustments. The antenna to have it checked) to be sure it is must be rotatable, either by hand (turn- properly aligned and in tip -top shape ing the pipe column with a wrench) or to deliver its maximum performance. with a motor. Keep the over -all height Usually, the cheaper sets employing a under 100 feet to avoid having to install minimum of tubes will require a larger a flasher beacon on top of the mast in input signal to drive the video channel compliance with CA A regulations. successfully. If the location is in a low - Most marginal antenna installations noise area, the signal can be built up run from 60 to 95 feet over -all height. to the level required by any set on the It is important to get above trees market; but if there is noise and inter- and surrounding objects, but excessive ference, that will also be amplified by height means increased length of trans- the boosters and results will be unsat- mission line, with increased losses. Use isfactory. a minimum length of co -axial cable or All marginal installations require the transmission line to make the installa- use of from one to three preamplifiers tion. Use co -ax for noisy locations and or booster stages. You can buy several twin line for residential or country jobs. good ones on the market, or one can If a purchased antenna system is in- be built. (See RADIO- ELECTRONICS, Oc- stalled, directions for installation and tober, 1948, page 60, and November, matching to the set will be furnished. It The upper array on this 90 -foot -high mast is 1948, page 48.) It is generally necessary is a good idea to do some experimenting beamed on Cincinnati. lower toward Chicago. to use two or three stages of pream- when it comes to matching inputs; there plification. To avoid oscillation due to is often a very great mismatch which coupling, many users prefer to employ results in a very poor transfer of sig- factory -made boosters in cascade. If nal. A little patient trial- and -error may trouble is encountered because of oscil- make a big difference in the input .sig- lation, instability, or failure to secure nal. Keep the lead -in away from metal a tunable peak, it can often be corrected objects. Support it on a minimum of by making changes in the input or out- stand -off insulators and avoid sharp put lines. Of course, some boosters may bends or turns. be inherently unstable; in many cases it will be simpler to try another one Where to get a mast when tracing down the source of trou- For lightning protection, it is advis- ble. Usually two different makes work able either to ground the pipe mast or better than two of the same make when to run a separate ground wire to the connected in series because there is less top, as is done to protect utility poles. chance for interaction between the two Follow the National Electric Code. Fre- units. quently your local power-and tight corn- pany will -set a= .pole--at a -very -reason -- Get a good antenna able price, as they have all the neces- To get any reception in a marginal_ sary equipment and can do the work in area, you must bring the maximum sig- a minimum of time. You can mount nal into the set, so the antenna installa- your antenna on this pole, which is tion is the most important thing to con- climbable and requires no guy wires for sider. Several antenna systems now on its support. Several marginal installa- the market give good results in mar- tions we visited had used this service ginal areas, and most users have pre- with considerable satisfaction. Over a ferred to buy a ready -cut antenna sys- period of several years, such a pole tem. Decide what station you want to should be a very good investment. receive and then either get an antenna It takes a lot of work and patience cut for that particular channel, or get to get a marginal installation to funs- one you can definitely tune to the de- , tion properly. Do not expect consis- sired channel. Properly spaced direc- tently good pictures or uniform results. tors and reflectors are a necessity. Re- Television is here to stay, and it now member that straight dipoles have bet- appears that good reception may be ter directional characteristics than the possible at distances far beyond those folded types. Usually, a multiple array at first established by the engineers as is the only answer to the problem of the maximum at which a satisfactory getting a signal into the set, and the picture could be received. only type of antenna that will give any After becoming thoroughly familiar usable results. The so -called "broad- with a. particular setup, the operator band" types that cover all channels are can anticipate the times of best recep- no good for use outside the line of sight tion. Marginal TV is just beginning to of the transmitter. If the set is really open up on a national basis, and there far away from the transmitter, there are plenty of problems yet unsolved. will be trouble from all kinds of inter- Those who are now out on the fringe ference and stray noise pickup -auto- are having an unusual opportunity to rhobile and airplane ignition systems, assist in solving those problems by ac- cloud reflections, static, random noise, tually trying for reception under the tube noise -so the antenna must be varying atmospheric and climatic con- tunable and highly directional to mini - ditions encountered from day to day. Two photos of another marginal installation. JANUARY, 1949 301 Television Cover Feature CUSTOM -BUILT Projection Televisers TELEVISION kits are becoming a its sales efforts on the new model ex- recording - television combinations to new and important factor in the clusively at radio servicemen. Other harmonize with fine furniture. Their radio technician's life. Hampered companies have been following a paral- slogan is: "Any cabinet or any installa- in many cases by franchising sys- lel course. This is a sharp break with tion." tems, the kit is in many cases the wedge former practices in television kit dis- Wiring up an ordinary kit, they find, with which he can pry open the rich tribution. takes a little more than a day, unless television field. The would -be televiewer The technician finds kits reasonably bugs are encountered. For this a fee of buys his kit from the serviceman, who available, the public clamoring more $50 is charged the owner of the tele- assembles and installs it for a fixed fee. and more for televisers, and the assem- viser. This rate seems moderate, and is Advantages of the system are three- bly work not too difficult. There are new partly explained by the skill of the fold. The kit manufacturer knows that problems, but they tend to follow def- technicians, who are at home with prac- :As equipment will perform better if as- inite patterns, and once licked in one tically any type of kit, and thus run sembled and installed by a skilled tech- receiver, are easily recognized and over- into fewer difficulties than might be nician than by even the cleverest ama- come in the next. If the radioman expected. It is certainly far less than teur constructor. The customer has a charges an assembly fee sufficient to the factor which must be charged to wide range of choice in cabinet selec- meet these unexpected difficulties, he wiring in the price of a commercial tion-or may even have his set built will find himself in a profitable as well televiser. into a wall -space or an existing piece as interesting field of radio work. The projection jobs were a trifle new of furniture. And the servicing problem Among the alert radio technicians at the time our photos were taken, but -doubly troublesome in kit-built re- who have taken advantage of the oppor- Glassman and Mendelsohn find that in ceivers-is solved to the satisfaction of tunities in custom television assembly spite of their greater size and com- manufacturer, televiewer and service- and installation are Irving Glassman plexity, they can be assembled in about man. and Leonard Mendelsohn, proprietors 50% more time than the older direct - Manufacturers are orienting them- of Hi -Q Radio of Brooklyn, N. Y. The viewing kits. In the Television Assem- selves more and more toward the serv- two partners appear in the photos at bly receiver, this is partly explained by iceman as television kits become more the bottom of the page, Glassman in the the semi -ready condition of the kit, complex. Projection -type televisers, striped sweater and Mendelsohn in the which has the front end (a Du Mont whose extra -high -voltage power sup- white shirt. Organized a little less than Inputuner), the i.f. strip, and the high - plies and optical systems add to the two years ago, Hi -Q has assembled and voltage power supply already wired. difficulties of the inexperienced con- installed more than 200 television sets, Fees for assembling projection receiv- structor, are a natural for the skilled as well as numbers of special sound ers have not been fixed, but would prob- technician, and their manufacturers are jobs. Specializing in custom -work, they ably run a little more than 50% higher not slow to realize it. Television Assem- welcome jobs out of the ordinary line, than those charged for the small kits. bly Co., whose new projection job is the such as closet, wall, and fireplace tele- Assembly naturally leads to installa- subject of this month's cover, is aiming vision installations or special radio- tion and servicing. The man who has put the set together is the logical one to repair it. Hi -Q makes a contract for installati in and a year's servicing. The yearly contract rate of $65 -which in- cludes installation and high- and low - frequency antennas with separate lead - ins- represents a cut -to- the -bone figure due to the competitive situation in New York. The partners justify it on the basis that they can make money at that figure if they have more than 200 con- tracts, and that renewal service con- tracts will represent a greater margin of profit than original installations. The partners have a strict cost - accounting system, and know that at present they have eight service calls per year per set, and that each call costs $4.11, including all overhead. It is on this that they base their figure of a minimum of 200 contracts for a prof- itable business. The example of Glassman and Men- delsohn is being followed-and is worth following -by radio technicians in all television areas. To repeat and empha- size what has previously been said: if the radioman charges enough to meet unexpected difficulties and reverses -as well as his straight labor -he will find an excellent new field in projection tele- The Hi -Q partners, Glassman (in rear) and Mendelsohn (working on projection lens) vision kit assembly and installation. RADIO- ELECTRONICS for Theory and Design 131 Pocket Micro - Receiver By RICHARD HENRY ANEW receiver put on the mar- ket by Micro -Electric Products, Inc., appears to be very near the smallest size possible for a The Micro radio receiver as in three -tube set. Mounted a brown plas- compared with a package of tic case approximately one -third larger cigarettes. Earphone than a of and its standard package cigarettes, plug the Micro receiver is even smaller than ore in the foreground. many hearing aids. Placed in a shirt pocket, it slips down out of sight, the lead to a metal filing cabinet or type- spring with a only evidences of its existence being a slightly longer one may writer brought in additional signals, al- cure this condition. slight bulge and the flesh -colored an- though too good tenna and earphone wires. an antenna damaged Anyone who is not used to a regen- reception because of the set's lack of erative radio may have some trouble Despite its miniature dimensions, the selectivity. receiver contains three Raytheon sub- with this set. Critical regeneration con- One point concerning the receiver's trol and body capacity both affect the miniature tubes. CK512AX's are used mechanical as arrangement is of interest. receiver. These points will be quite fa- detector and first audio amplifier, The tuning knob, mentioned, and a CK522AX is in the output stage. as slides miliar to the ham or shortwave experi- up and down in a slot. The tension of menter, who will find operation quite The resistors and capacitors, as well as the small spring the output transformer, are miniature placed under the panel simple. components, is not sufficient to hold the tuner's set- The set is an interesting experiment such as those used in hear- ting all When ing aids. As the at times. placed in a shirt in adapting old principles in new de- photograph indicates, pocket, for instance, the cloth rubs all the parts are mounted on a fiber sign. It remains to be seen whether the chassis. against the knob, detuning the set. listener will accept a regenerative por- Though it was not tried, replacing the The circuit is a fairly standard re- table radio. generator. A departure from usual practice, however, is the tuning ar- rangement. The antenna, grid, and tickler coils are all wound on a single form. A powdered -iron core running through the form is terminated on a threaded rod bent at a right angle. This projects through a slot on the front of the case and a very small knob is screwed onto it. Sliding the knob up and down tunes the receiver. There are calibration marks on the case but no numbers, presumably be- cause, like all regenerators, the oscil- lator changes frequency so readily due to changes in the setting of the regen- eration control and hand capacity that numbered marks would not be very helpful. The tickler coil is not wound directly over one end of the tuning inductance in the usual manner. Part of it is Exploded view reveals construction. The tuning slug is just ahead of the tubes. spread out along the tuning coil to keep r"--- _ ALLIGATOR CLIP CN512AX CN522AX regeneration as even as possible over the whole tuning range. REGEN CONT ((DOT 1:112DOT The regeneration control is a minia- 25N .0005 4 1 f-- CK5I2AX (2) 5 4 3 2 1 CK522AX 5 3 2 ture hearing-aid potentiometer. The IOON knob projects slightly from the side of :311 the case. The earphone, a crystal unit, .001 .001 is .0002 fitted with a clear plastic ear plug 5 H /IMA XTAL designed to fit the ear comfortably. Considering the fact that the circuit is a simple regenerator, results are ade- 5MEG quate, certainly unusual for the physi- 20uµf cal size. Distant (suburban) reception was very poor, but in downtown New York City there was satisfactory re- ception from several local stations with no antenna other than the 21/2-foot clip - A B- 8+22.511 At-Lo lead attached to the set. Clipping the The schematic. Circuit is regenerative -using o shunt -fed tickler -with two audio stages. JANUARY, 1949 321 Theory 111141 Design Designing L-C Audio Filters A nomogram eliminates all math in designing filters By RICHARD H. DORF WITH the two nomograms on grid resistor. Because the plate resist- old audio transformers and chokes. 33 you can design your ance of the pentode is high, its shunt- To find a coil of a certain value, own audio filters without ing effect on the plate load resistor is consult a resonance chart and choose tediouso mathematical calcu- negligible and the line between the a capacitor which will resonate with lations. The nomograms are for the 6SJ7 plate and the following grid is, the desired coil at some audio frequency. constant -k filter, a simple but effective in effect, a 100,000 -ohm line. If a triode, For example, the 5 -henry choke of Fig. type of L -C circuit. The cutoff slopes such as the 6C5, were used with the 4 would resonate with a .005 -µf capaci- you will get with them will be almost same resistors, the low plate resistance tor at 1,000 cycles. Try placing various as sharp as the ideals shown in Fig. 1, shunting the plate resistor would bring depending on the d.c. resistance of the the net resistance at the input of the I. coils you use. For sharpest cutoff use filter down far below 100,000 ohms. The low-resistance coils. circuit is shown in Fig. 4. IN a C/2 OUT IN a 2L = our To find the values for the coil and o LO PASS HI PASS fr CPS tr capacitors, find a straightedge (trans- 60 60 100 /200 400 600600 2K / 4K 6K parent plastic rulers with a black line Fig. 3-Half- sections give less sharp cutoff. down the center work best) and turn coils in series with the capacitor across IIill to Nomogram 1. The cutoff frequency +01 you have decided on is 6,000 cycles, the output of an audio oscillator, with PM.Jig pmmi,II and the terminating resistance R (or a vacuum -tube voltmeter also across the oscillator. Choose a coil which will to 111111f1 III the nominal impedance of the line) is 100,000 ohms. Place the straightedge, cause the meter to dip at some fre- is 112111/A1 III quency lower than the selected one 0E111 as shown by the dashed line, so that III it touches 6,000 cycles in the column (lower than 1,000 cycles, in this case). ii t Then start removing core laminations PAU and 100,000 ohms in the R column. 11 III or coil turns (or both) until the meter Then read the value of L from the VAIIISIi1III dip occurs at the desired frequency. D in center scale. Since this is to be a low - maim= pass filter, the calibrations at the right To duplicate the conditions under which :; 111111011 III is I of the center column are used. The the coil will operate in the filter, it XMISSION DB a good idea to choose the same capaci- value found is 5 henries. Referring Fig. I- Dotted ines show how re ponse peak back to the original filter diagram in tors and resonant frequency for this if terminating resistance is high or absen trimming adjustment as will be Fig. 2 -a, note that the choke to be used used is marked "L ". Therefore, you assign in the filter. The resonant frequency is To use the nomograms, first decide one -half cutoff for a low -pass and twice what kind of a filter you need. For a 5 henries to L in Fig. 4. To find the capacitances, use the cutoff for a high -pass filter. For that phonograph scratch filter, for instance, of Fig. 4, for instance, the 5 -henry you might want a low -pass filter which same method with Nomogram 2. C, read again from the right center column, is coil might be selected by placing it in would cut off at 6,000 cycles, leaving with approximately .00055 µf, or 550 µµf. series 550 µµf and trimming for all lower frequencies practically un- a meter dip at 3.000 cycles. touched. Having decided on a fairly If it is possible, removing turns is - a 6 sharp cutoff, choose one of the full LO PASS HI PASS the best plan, because the resistance section filters shown in Fig. 2. For a L/2 L/2 2C 2C of the coil will make the filter results 0- 1 F cutoff only half as steep as Fig. 1 indi- depart somewhat from the ideal abrupt = cates, you would choose a half- section, IN C OUT IN L OUT cutoff. Reducing the resistance by re- as in Fig. 3. moving wire will raise the coil's Q and Either of the low -pass filters shown T SECTION T SECTION help lessen the effect. in Fig. 2 -a, the T or pi, could be used, L C If odd -value capacitors are specified, so you can decide on the basis of they can be made up by paralleling economy. A filter with only one choke IN C/2 C/2 OUT IN ? 2L 2L OUT standard sizes. It should not be neces- being cheaper than one with two chokes, to PI SECTION sary parallel more than two capaci- the pi filter would be selected. PI SECTION tors, since the greater precision ob- First determine where the filter is Fig. 2 -These are basic constant -k filters. tained with more than two is not worth to be placed. It could be in a low - while. impedance line if one is used, but sup- However, the capacitors in the filter After the filter is connected, it may pose in this case you decide to place you are using (Fig. 2 -a) are marked be necessary to trim it slightly. This it in the amplifier between two tubes. "C /2 ". Therefore you divide 550 by 2 can be done by making further adjust- The only important thing to know here and assign the value of 275 µµf to ments to the coil. If exact results are is the resistance load the filter will face. Cl and C2 in Fig. 4. wanted, running a series of curves A filter will work with any load re- And there's your filter! with an audio oscillator and output sistance as long as the resistance across meter will show just what the filter the filter's input is equal to or greater Constructing coils does. than the output load. But it will work The only real problem in making up best when inserted in a line of uniform filters is the inductors. Coils made for impedance-one terminated in the same filter purposes can be obtained from resistance at both ends. transformer manufacturers; some even The resistance - coupled amplifier have an inductance which can be varied chart shows that a 6SJ7 (the tube you over a limited range. But these run to are using at the input to the filter) anywhere between $5 and $20 or more. will work with a 100,000 -ohm plate load A simpler and much less expensive so- resistor and a 100,000 -ohm following lution is to dig into the junk -box for Fig. 4- Sample filter is shown in dashed box. RADIO -ELECTRONICS for Theory 1111111 Design 33 OMOGRAM NOMOGRAM wl@ß Gza f0 MS) OHMS 0 le CYCLES) IOOK 60K 60 K .000025 .0001 50K .00004 .0002 40K 30K 30K .0004 .0006 20K tò008 20K ;001` .002 10 .004 8K 8 .006 .008 6K 01 6K 5K 4K .02 4K 3K 3K .04 ,.06 2K .08 ;1 .2 K IK .4 800 800 .6 600 .8 600 500 500 500 400 400 400 300 4 6 200 8 200 '10 20 100 100 40 60 80 60 60 ß0 60 '100 50 50 40 200 40 30K 400 30 600 50 20 60K 2504 1000 80K IOOK 10 These nomograms make it possible for you to design audio filters without making calculations. Nomograms were derived from formulas shown JANUARY, 1949 I.111J NI 1.1 Y I SSW u Will V I l.. Loa./ I WIY" SU luu Visual FM Alignment How to use an oscilloscope and FM signal generator to best advantage for rapid and accurate alignment By JOHN B. LEDBETTER* ETHODS of aligning FM re- modern FM generators use reactance - ceivers accurately without the tube modulators to provide an adjust- aid of an FM signal generator able sweep width up to 200 or 250 kc. and oscilloscope have been This sweep is synchronized with the has two limiters, the signal voltage for scope should described (RADIO -ELECTRONICS, Novem- oscillator time -base sweep to obtain an the vertical input of the ber, 1948). While these methods do al- indication of the frequency response or be taken from the load resistor of the low accurate adjustments to be made, overall characteristics of the circuit un- first limiter stage as outlined above. it is always desirable to check the lin- der test. The second limiter can be aligned after earity of the FM detector visually. the i.f. stages have been adjusted. It is also very helpful to determine the Aligning the i.f. With the scope FUNCTION control set alignment and response curve of r.f. Generally speaking, i.f. alignment of for external sync, connect the sync - and i.f. stages by eye. These checks of FM receivers closely follows the pro- input terminals of the scope to the course can be made only with the aid cedure used in alignment of TV sound sync terminals of the generator and of the above instruments and it is rec- channels. (See "Video Alignment" by adjust the horizontal sweep frequency ommended that they be employed Robert N. Vendeland in the September, of the scope until it is synchronized with wherever possible. 1948, issue). There are certain differ- the modulating frequency of the gen- ences, however, especially in the various erator. The deviation is then increased Instrument requirements types of FM discriminator circuits. until the response curve is spread across the desired portion of the scope Although the only instruments nec- These must be taken into consideration when aligning a straight FM receiver. screen. The signal voltage from the essary for visual alignment are an generator should be fairly low to pre- oscilloscope and FM signal generator, As stressed by professor Vendeland, the manufacturer's alignment notes vent overloading and distortion in the a d.c. vacuum -tube voltmeter is helpful i.f. stages; for this adjustment, the to determine the exact frequency at should be closely followed wherever pos- sible. If no instruction manual or align- generator output should only be high which the d.c. output of the discrimin- enough to give good limiter action. ator is balanced to zero. (For this ad- ment data is available, the general alignment procedure as outlined herein If the i.f. stages are properly aligned. justment, the vacuum -tube voltmeter is a response curve similar to that in Fig. connected in parallel with the vertical is to be recommended. First, frequency response of the i.f. 2 should be seen. The pass -band should input terminals of the scope and the be 200 to 250 kc wide if the circuits are lowest possible meter range employed system may be checked by setting the generator to the correct center fre- in proper alignment. The double-peaked to indicate zero). curve shown in Fig. 2 is that normally The oscilloscope can be of almost any r LIMITER- --1 obtained with i.f. transformers of the type so long as provisions for connect- - overcoupled type; single -peak trans- ing to an external source of sync volt- more re- I I formers approach closely the in most age are included. This voltage L sponse curve in Fig. 3. cases is furnished by the signal gen- I.f. stages out of alignment may as- erator. Although a scope with a 3- or sume various forms of distorted re- 5 and easily -inch tube is more accurate a' (VERT INPUT sponse curves, usually similar to those adjusted, satisfactory results may be Fig. I-Connection of scope vertical input. shown in Fig. 4. Sometimes it is difficult obtained with a less expensive scope to ascertain whether these distorted such as the Philco Model 7019 shown in leads waveforms should be double -peaked model quency and connecting its output the photograph. This particular 0.1 (for overcoupled transformers) or necessary through a µf condenser to the incorporates all the features grid of the converter tube. In receivers single -peaked. Before attempting to for visual analysis. -Seeley align an i.f. stage, it is advisable to should employing a Foster detector, the The FM signal generator vertical plates of the scope should be try to find out whether the transformers cover the 88- 108 -mc band and have an connected across the discriminator load are of the overcoupled or single -peak i.f. range of about 4 to 11 mc. Modula- a type. Valuable time can be lost trying the resistor. In sets with ratio or Philco tion capabilities of generator should detector, it will be impossible to obtain to "flat -top" a single -peak circuit allow deviations of 75 to 100 kc on each visual indication of the i.f. response which was not designed for it. de- side of center frequency, with the curve unless an AM detector is used in If the manufacturer's service notes viation rate adjustable from 30 to 15; conjunction with the scope. are not available, the type of circuit 000 cycles per second (sine wave). A If the receiver has a limiter stage, may be determined quickly by connect- built -in sweep is also desirable. Most the vertical input circuit of the scope ing a loading network consisting of a should be connected across the limiter 0.1 -µf condenser in series with a 5,000 - *Engineer, WRAC, WCTS -FM, WKRC -TV Cincinnati Ohio load resistor as shown in Fig. 1. If it ohm resistor from plate to ground or RADIO -ELECTRONICS for FM 135 -..--. from grid to ground of the last i.f. ------zsoKc stage. If the transformer is over - - coupled, the response curve will change considerably, usually straightening out on one side. If the transformer is single - peaked, little change will be noted. Each i.f. stage must be able to pass bandwidth of 200 kc without the total Fig. 2 Fig. introducing distortion into the system. 3 Fig. 4A To check this possibility, each stage must be aligned separately, beginning with the secondary of the last ii. stage and working back progressively toward the converter. Each stage is "flat - topped" to give the symmetrical re- sponse curve of Fig. 2 or Fig. 3, de- pending on the circuit. For each stage, Fig. 4B Fig. 4C Fig. 5 adjustments are made with the signal generator connected to the grid of the preceding i.f. stage. If any stage fails to peak properly there is trouble in that stage which must be corrected before r going on with the alignment. The deviation has already been set J (as mentioned previously) so that the Fig. 6 Fig. 7 Fig. 8 desired curve spread is obtained on the scope. As each successive stage is aligned, it may be necessary to decrease Figs. 2.10 -Various the signal generator output to maintain response curves, as the desired height or size of scope the referred pattern and to prevent overloading. On to in the the other hand, a comparative check on text of the article. the gain of each stage may be made by leaving the generator output constant Fig. 9 Fig. 10 and noting the increase in image ampli- tude as each stage is aligned. curve, especially along the center por- will be noted in the departure of the The second limiter may be aligned tion. These two points of maximum waveform from its sine value. The by increasing the output from the sig- indication should coincide. flat -topped peaks in Fig. 9, for ex- nal generator slightly and adjusting the An S- shaped discriminator response ample, indicate overloading in a re- limiter for minimum output. In some curve (Fig. 6) may be obtained by sistance- coupled amplifier or inability cases the d.c. vacuum -tube voltmeter synchronizing the scope horizontal am- to handle normal signal voltage. The may not read high enough to indicate plifier with the signal generator sweep distorted curve in Fig. 10 indicates the proper setting satisfactorily. This voltage. Although this type of curve overload trouble in the output stage. adjustment may be made quite satisfac- usually allows sufficiently accurate dis- For extreme accuracy in checking torily by ear. The signal generator out- criminator alignment, an X -type curve audio- frequency response, the voice coil put may be reduced for the adjustment (Fig. '7) may be used for greater ac- should be disconnected and a resistor if necessary. curacy. With this type of response pat- of the same value substituted, since As mentioned before, a normal i.f. tern, it is possible to double -check the reflected impedances from the voice coil response curve cannot be obtained in entire curve for linearity. will affect readings. Frequency re- receivers which have ratio or Philco- The X curve may be obtained by sponse can be checked by noting the type FM detectors unless an AM de- using the same set -up as that em- amplitude of each audio frequency on tector is used with the scope. These ployed for the S curve. The scope the scope. Waveforms should be essen- cases can be aligned accurately, how- horizontal amplifier is then set to in- tially the same height for good re- ever, by observing the overall effect of ternal sweep and the sweep frequency sponse. For this test some sort of the i.f. signal on the response curve adjusted for 120 cycles. The scope sync output meter must be connected across of the FM detector, since the detector selector is then switched to external the output of the signal generator so is extremely sensitive to any change in sync and the external sync voltage that its output voltage can be kept the the i.f. response characteristics. picked up from any source which sup- same for all frequencies. plies 120 cycles. (This frequency can Audio response can also be checked Detector alignment be easily obtained by connecting the by using an output meter instead of a First, connect the vertical input of external sync leads across the input scope for response readings. A sub- the scope to the output of the discrimi- filter condenser of the receiver's power stantially flat response from 50 to 15,- nator and connect the scope sync -input supply.) 000 cycles should be present in the terminals to the sync terminals of the better audio systems. A drop in re- generator. Then connect an output Audio response sponse at the higher frequencies is to meter across the output of the audio Hum, distortion, and frequency re- be expected, but should not exceed 2 amplifier or across the speaker voice sponse characteristics in the audio sys- or 3 db in hi -fi systems. coil. The response pattern of Fig. 5 tem may be checked by connecting the While an inexpensive scope such as should then appear. (The slope may vertical input of the scope across the the one mentioned earlier in this dis- face either way, depending on the phase output transformer and feeding a sig- cussion does necessarily have its limita- relationship between the vertical input nal from an audio oscillator into the tions, it is quite satisfactory until a voltage and sync voltage). grid of the first audio tube. Sync volt- larger, more flexible scope can be Align in the same order as usual age for the scope is taken in the usual purchased. To the serviceman just be- (first the secondary, then the primary manner from the generator. As the ginning or otherwise limited financially, of the discriminator transformer). frequency is varied over the audible these more inexpensive instruments will Proper alignment is indicated by a range, the waveform of each frequency be welcomed as a means of doing the maximum reading on the output meter should assume the shape of a sine wave job right, while representing a mini- and maximum linearity of the response (Fig. 8). Any distortion or hum pickup mum practical investment. JANUARY, 1949 FM 36 I Radio Set and Service .Review The Emerson Conqueror is lowest- priced a.c. -d.c. re- ceiver for FM reception only THERE was a time not so long ago elements, so . rubber grommets had to the line, and, as a piece of wire, it has when radio's wise men predicted be used on either side of the tube to a certain amount of direct pickup. In that FM receivers could never be keep down microphonics. Now that the downtown New York it did just as well built to compete with AM table tube maker has hit his stride, Emerson as a half -wave dipole of twin -lead models on a price basis. That predic- engineers report that the new tubes hanging on the wall, picking up most tions are not always accurate was are solid and the rubber grommets are of the local stations well enough for proved last November, not only by the no longer necessary. all practical purposes. If it is used in election returns, but also by the Emer- The circuit, as the diagram shows, a poor -signal- strength area you can son Radio and Television Corporation. is extremely simple. The first three connect a standard antenna to the two Emerson's new a.c: d.c. FM receiver stages are completely conventional and terminals provided. Despite the lack of sells for less than $30, and is no bigger a ratio detector, also standard, con- an r.f. stage, results ought to be satis- than an ordinary AM bedside set. It verts the r.f. to a.f. The 12S8 used factory in most localities. receives most local stations without an for the purpose doesn't appear in most Though this is a small set and there external antenna and has more pleas- tube manuals. It is made, according to is a reasonable number of parts, a ing tone quality than its typical AM Emerson, by Tung-Sol. This informa- look at the under -chassis photo ought counterpart.' Designated Model 602, it tion may prevent a harassed service- to be heartening to servicemen. There is quiet when a station is tuned in- man from thumbing through his books has long been an impression in the very little tube or r.f. noise is heard and concluding that "there ain't no service trade that a radio production and hum is far enough down to be such animal." There is. It may be a line consists of a number of workers, negligible. The prophets, in a word, good idea to make a note of the pin each of whom solders in one component have lost whatever honor they possessed numbers shown in our diagram and as the set goes down the moving belt. in their own country or any other. file it away. At the end of the line, the resistor and Just six tubes are used in the cir- Loop antennas don't seem to be prac- capacitor hookup rises up about a foot cuit-a converter, two i.f.'s, a com- tical for v.h.f. -at least as yet (why above the overturned chassis. The last bination discriminator and first audio, go out on a limb ?) -so Emerson has man to work on the set, according to an output, and the power rectifier. All, provided a three -wire line cord. The the theory, is a specialist, chosen for with the exception of the 12S8-GT dis- third (center) wire is normally con- the large size of his feet. It is his sole criminator- audio, are miniatures. One, nected at one end to an antenna post duty to place the wired chassis, bot- the 12BA7 converter, is being mass- on the rear of the receiver and is open tom upward, on the floor, and tread the produced for the first time especially at the other. Because it runs along parts and wiring into place. for use in this receiver. Products of the power cord for about 70 inches it You won't find much of that in the the first runs occasionally had loose is apparently capacitively coupled to 602. Wiring .a pretty well in the open 12S8 -GT 3585 12BA7 128A6 12BA6 0ISCRIM /IST AUDIO 470K OUTPUT PM SPKR CONV i.-. DISC TRANS .0005 AVC¡' f t .01 S 6 3 330µµ 6 334 5 2 .0047 4 1-7 5 4- .001 100 7 100 100 470K 2 óoa7 .0047 68K .001 -17VV---IH -MNr (15uuf, 22K f 15uuf 4.7MEG .002 5004 180 A01 1 I-----11--Sy ---11-- Y 2.2MEG 509110 50 RFC yIK L r 314d 39 .0047 y x .0047 .05 O7'-o 0-,000 /P77 TEMPERATURE 4 RFC 4 5 RFC 3 4 3 6 4 SW ON VC Op I17VAC/DC COMPENSATNG 12BA6 12BA7 3585 35W4 The Emerson Conqueror, Model 602, an a.c. d.c. receiver which works on FM only. A standard circuit with a ratio detector is used. RADIO -ELECTRONICS for FM j 37 and almost any component can be re- moved without an anesthetic and major surgery. All the capacitors except the electrolytics and a couple of micas are miniatures, so they take up very little room. From the user's standpoint, this re- ceiver is easy to operate and gives good results, though there are a few points that need comment. It wouldn't be real- istic to expect concert -hall quality from the 4 -inch speaker, but listening quality i; judged to be more pleasing than that of a comparable AM model. That is due to two factors -the absence of noise un- der almost any conditions, and the pe- culiar "cleanness" of FM. Turning up the volume to maximum won't produce great waves of sound, but it won't make you cover your ears either. The dis- tortion is much less than on similar AM sets (there wasn't any to speak of when a station was tuned in correctly) and the tonal range appears to be well - balanced. The model examined showed fre- quency drift for some time after it was turned on. However, it was an advance Emerson Model 602 from the rear. Attach- model and didn't have the temperature - ment of the linecord antenna is shown. compensating capacitor across the os- cillator coil which was added to all except the very first receivers off the production line. According to Emerson, the capacitor reduces drift to a slight change during the first few minutes of operation. The drift, even on the un- compensated set, isn't particularly an- noying, especially as one can't expect a five -year lease on W W V for the price of a small FM receiver. The dial scale is a semicylindrical strip of metal, in one end of which is set the volume control and in the other the tuning shaft. Two clear plastic knobs project slightly from each end. A dial cord turns the capacitor shaft and moves the frequency pointer. The stringing seems remarkably uncompli- cated, but the pulleys are non -rotating, a factor that may possibly cause wear on the cord. The volume control mount- ing-on an angle bracket out in front of the chassis-makes replacing it easier instead of more complicated, as non -standard so many of the modern Underchossis, showing dial -cord assembly schemes do. and control shafts. R. f. wiring at right. There are two points to which some objection may be legitimate. First, there is no pilot light. Though this means there is one less gadget to go bad, it SERVICEMAN'S RESISTOR QUIZ also means that there is one more way Here are five questions which will 3. Now the 1- and 2 -watt resistors are to run up a light bill. (The between - show you whether you know as much placed in parallel. How many watts station noise from the set is very low, about dealing with resistors as you can the combination dissipate? especially when the volume is turned thought you did. Write down your an- 4. You have a volume control which is down, so it's easy not to realize the re- swers, then turn to page 90 and check damaged beyond repair, but you ceiver is on.) your score. can't find a replacement. How can Second, one side of the power line is 1. Checking a dead receiver, you find you make a temporary repair with grounded right to the chassis. There that every circuit except the audio fixed resistors? are three exposed chassis screws under- volume control is in perfect condi- 5. On your bench is a receiver in good neath and two in the rear, so there is a tion. Rotating the control has no ef- condition. You want to find out definite shock hazard. fect whatever. Using nothing but an whether the volume control is in the The 602 has just come out and align- uninsulated screwdriver, how would audio section or the r.f. section of ment instructions are not available at you diagnose the trouble? the set. There are no stations on the this writing. The circuit, however, is 2. A circuit contains a 1 -watt resistor air and your signal generator is out so straightforward that it should be and a 2 -watt resistor in series. The of order. How do you find out which possible to follow any good set of gen- resistance values are unknown. How stage the volume control is in eral FM alignment instructions with- many watts can the circuit dissipate? without removing the set from its out trouble. Don't decide this one too quickly. cabinet? JANUARY, 1949 381 Amateur III V. O. From Surplus An excellent variable frequency control which can be constructed inexpensively from a 274 -N surplus transmitter By GEORGE F. MARTS, Wp)TDH III TO keep up with postwar compe- calibrating -but because of a difference added stage would have provided the tition in the congested amateur in price the BC- 458 -A was chosen. necessary isolation, but the second tube bands, some sort of variable fre- Those favoring an 80 -meter crystal was put in to increase the power output. quency control is necessary. The substitute should choose one of the The first step is to remove everything W¢TDH transmitter had a good crys- units that cover that band. that will not be needed. All the final tal- controlled exciter using a harmonic - The modified circuit uses a 6J5 as amplifier parts are removed, as well as type 6V6 -GT oscillator stage driving the oscillator, exciting a 6AG7, which the antenna components and relays and an 807 doubler -amplifier. This supplied drives a 6F6. The 6J5 plugs into the associated wiring. To retain the gear - enough drive for the medium -power original 1626 socket without any drive dial system it was found neces- final amplifier, making an elaborate changes in the original wiring. All sary to use part of the framework of v.f.o. exciter unnecessary. We decided original wiring is removed from the the p.a. tuning capacitor. The dial gear on an external v.f.o. crystal substitute crystal and 1629 tuning-eye sockets to mechanism is fastened to the stator whose output could be plugged or accommodate the isolation stages. R.f. frame, which is needed to hold the switched into the crystal oscillator chokes are used instead of tuned tank gears properly for smooth dial move- stage. It had to be inexpensive, com- circuits in the buffers, so that only one ment. pact, and self -powered, with good fre- tuning control is necessary. Making Remove the rotor and stator plate quency stability. the inductance of the r.f. choke in the assemblies and saw the stator frame One of the Army SCR -274 -N (or 6AG7 plate circuit different from the in three places: saw off the two bot- its Navy twin, the ARC -5) aircraft other two r.f. chokes prevents coupling tom strips, leaving the parts with the transmitters makes an ideal founda- between grid and plate circuits. One tapped screw holes, which are used to tion. The master -oscillator section is MIKE CONN an excellent v.f.o., and there is ample 6AG7 .0001 6F6 .0001 CO -AS space for a power supply after removal e 04- 3 PADDER TUNING I IMH of the final amplifier components. R72 SIH pC60 C63) I .0001 ae Each SCR -274 -N transmitter consists S C68 o of a master oscillator using a 1626 2.5MH 2 B C59 I8Ou1'f 31'1'f R67 3 CSeA.HIOONS.tS triode, (a 12J5 can be used) exciting 2.SMH C568 300 -ÌOf2- two parallel 1625's (12 -volt 807's) in ' C64 the final amplifier. The oscillator and 6J5 Gi final tuning capacitors are ganged, and ¡ NOT USED I the dial system has an excellent worm - C61 B 5 I 30H /5OMA li 5v gear drive for vernier tuning. There 5n 25w is also a crystal and a 1629 (12 -volt 006 T53 *.NOT USED 1 6.3V FIL TRANS j o 340V 6E5) electron -ray tube for frequency L 6 ORIGINAL OSC ASSEMBLY calibration. 340V Four transmitters in this series are o f1 available, each with a different tuning .05 fSW 5Y3-GT T 2 -1 two of them be , 6.3V 1 ILSOD3 range. Either of can DISCONNECT 8 7 .F /VR150 made to cover the 80 -meter band, and 7 r dl, EXT. SEND -RECEIVE RELAY CONN. either of the other two the 40 -meter BOTTOM VIEW 153 CONNECTIONS band. We chose the BC- 458 -A, which The SCR -274 as modified to make a v.f.o. Mike jack output connects to amplifier cathode. has a range of 5.3 to 7 mc, because it I- SCR -274 -N transmitter, frequency range as de- 5 -volt, 2 -amp.; 6.3 -volt, can be made to cover the 40 -meter sired. Tubes: 1-615; 1 -6AG7; I -6F6; I- 5Y3 -GT; 1- band by retuning the slug and padding Resistors: 1- 300 -ohm, I -watt I- 5,000 -ohm, 2S -watt, 003 /VR I SO. adjustable; I-100,030-ohm, 1/r -watt. Miscellaneous: 1 -30 -h, 50 -ma filter choke; 2- condenser in the oscillator -coil assem- Capacitors: 3- 100 -0, mica; 2- 0.5 -pf, 600 -volt, s.p.s.t. toggle switches; I- single- circuit, shorting microphone 7 paper; 2- 20 -µf, 450 -volt electrolytic. phone jack; I- single -circuit, cable -end bly. The BC- 459 -A, which covers to 9 assembly; hardware. termi- R.f. chokes: 2- 2.5 -ml; 1 -1 -mh. connector; I- pilot -light mc, could have been used without re- Power transformer: 6110 -volt, center -tapped, 50 -ma; nal strips, etc. RADIO -ELECTRONICS for Amateur 139 refasten it to the chassis, saw the left capacitance -coupled to the plate of the to the oscillator stage of the transmit- forward side of the frame close to the oscillator, leaving coil section C unused. ter. Approximately 1/z watt of power is front frame plate. Remove the sawed The bottom view of the coil connections obtained, enough to drive the transmit- portion by bending it backward and shows which connections to retain. Also, ter's oscillator tube. forward, forcing the right rear joint the crystal calibration feed tap on coil loose and leaving an L- shaped frame. A is not used. Final adjustments Remount this in its original position. The power supply is conventional, Little adjustment is required before The gears can be easily refastened to with a voltage -regulator tube con- putting the v.f.o. in operation. The the side of the frame and the flexible nected across the output to provide a slider of the current- limiting resistor shaft coupling between the two worm constant 150 volts. All circuits are should be adjusted with the key closed gear shafts reconnected. The dial operated at 150 volts, except the 6F6 mechanism should operate as smoothly which has the full supply voltage on as before. its plate. No particular care need be The p.a. (1625) tube sockets can be taken in layout. The filter choke and removed by inserting a knife or screw- filter condensers are underneath the driver edge under the lips of the alumi- chassis, with R mounted on top to num shields and prying upward all allow its heat to be dissipated in the along the edge. Push the sockets open. through the openings. We covered the openings . with a piece of aluminum, Wiring problems using the many holes left by the pre- The wiring of the r.f. section may vious removal of parts to bolt it to look difficult because of the small space the chassis. Two holes are punched available for mounting and soldering in the center of the openings to ac- the parts, but is it really quite easy. Parts layout atop the converted commodate sockets for the rectifier Much time and work is saved because transmitter. and voltage- regulator tubes. They the oscillator coil is already mounted until the tube ignites with the familiar were placed there so as to be under and wired. The filament wiring should bluish glow. Since the top frequency of the opening in the cover to make future be hooked up first. Note in the circuit the BC -458 -A just hits the lower end of replacement easy. Remove the filament diagram that the oscillator filament the 40 -meter band, it is necessary to resistor from across the 1629 socket. voltage is fed through the A and B shift the entire band lower on the dial Remove, too, the chassis connector be- sections of the oscillator coil T53. One by screwing the slug adjustment of the side it and cover the opening with a side of the filament is grounded through oscillator coil counterclockwise and piece of aluminum to complete the the A section, and this connection making fine adjustments with the pad- shielding. should remain unchanged. The hot ding condenser C60. Of course, the di- From the front panel of the unit, filament connection should be made rect reading of the dial was thrown off; remove the antenna coupling control, from the ungrounded end of C61 since but the dial can be used as a logging with its locking knob and the antenna heater pin 2 is connected through coil scale, or the correct frequency readings inductance locking device. Enlarge the B from that point. may be painted over the original read- opening left by removal of the antenna Wire the midget 100 14 coupling ings. Building this v.f.o. with a BC- coupling control to receive the shank capacitors and the grid resistors next, 459-A, whose frequency range includes of a s.p.s.t. toggle switch for the a.c. using a small porcelain stand -off in- the 40 -meter band, will enable you to line. Mount a similar high -voltage off - sulator as an anchor point for the last retain the direct -reading calibration. on toggle switch symmetrically on the capacitor where it connects to the co- Any frequency error due to changes in right side of the panel above the dial. axial cable. wiring can be compensated with the Any remaining holes in the panel can It is advisable to mount the r.f. padding condenser, which can be be filled with suitable machine screws chokes at different angles to keep their reached with the chassis cover replaced, to improve appearance. The closed - fields from coupling. A two -terminal through an opening provided for it. circuit keying jack J is placed on the strip was mounted on the side of the The v.f.o. was coupled to the regular lower left, and the opening left by the chassis nearest the power transformer crystal harmonic-type oscillator stage antenna insulator is used for a pilot - to provide connections for an external through a grounded -grid arrangement. lamp assembly. send- receive relay. Four rubber feet The inner conductor of the co -axial In the oscillator section, leave the were mounted on the bottom chassis cable is connected directly to the cathode two mica condensers mounted on the cover to absorb shocks and vibration. of the tube, while the grid is grounded. side of the chassis behind the oscillator As an added precaution the whole unit Selection of crystal or v.f.o. operation tuning condenser in their original posi- rests on a sponge- rubber kneeling pad can be simplified by the use of a switch tions. Remove the can containing the when placed on the operating table. in the transmitter. three .05 -µf condensers (C58A, C58B, A 3 -foot length of 52 -ohm RG -58 /U This little unit will be found to facili- and C58C) from the rear of the chassis co -axial cable terminated with a single - tate quick, convenient frequency shift and place it on the side to allow more contact, pressure -type microphone con- while maintaining excellent quality Of freedom for soldering and mounting nector is used to couple the v.f.o. output the transmitter's emitted note. other parts. Leave the three octal sock- ets on the chassis rear in their original positions. Retain the connections on the oscillator tube socket except pin num- ber 3 (plate), as shown in the diagram. The dashed box in the diagram encloses the remaining original components. The connections on the other two sockets must be removed to allow for wiring of the 6AG7 and 6F6 buffer stages. In the original circuit the grids of the final amplifier tubes were excited through section C of the oscillator coil assembly. Heavy grid drive is un- necessary in the new circuit. To mini- mize frequency variations caused by loading of the frequency -control in- ductance, the grid of the 6AG7 was The filter choke is mounted on the side apron of the chassis. Main tuning capacitor at left. JANUARY, 1949 401 Amateur Wired -Wireless Control Unit This novel wired- wireless control unit makes pos- sible remote operation of many types of equipment FREQUENTLY amateurs and ex- replaced, without circuit changes, by perimenters have need for a means. a 6SA7 and the 12AT7 by a 12AX7 or of controlling a transmitter, audio 6J6.) The oscillator section of the amplifier, door opener, or other de- 6BE6 is connected as a 455 -kc oscil- vice located at some remote point. If lator, and the mixer section as a modu- the device to be controlled and the lated amplifier. The oscillator coil Ll control point are supplied from the is a 2.5 -mh r.f. choke tapped at the same power line, the carrier- current, first pie from ground. The amplifier remote- control system described in a tank coil L2 is a modified 455 -kc i.f. Photos courtesy of General Electric Company recent G -E Ham News will do the job transformer. One winding is removed The receiver is located at the remote point. and with L3, 10 of No. nicely. replaced turns be set to give maximum a.f. signal The system consists of a transmitter 20 wire wound close to the B -plus end without distortion. is to 455 kc by and a receiver, both operating on of L2. L2 tuned C10, The receiver is a t.r.f. unit consist- 455 kc. This combination permits re- the trimmer of the i.f. transformer. ing of a 6BA6 r.f. amplifier, The 12AT7 is a amplifier and and a mote switching and the transmission speech 6BF6 a.v.c. and relay- control tube. The and mcdulator. The first section provides of a.f. signals. transmitter A 6SK7 or 6SG7 and a 6SR7 may be 1 sufficient gain to work from a high - receiver circuits are shown in Figs. substituted for the 6BA6 and 6BF6, and 2, respectively. gain microphone or pickup, and the respectively. The input transformer of The transmitter uses a 6BE6 and second section modulates the suppres- the receiver is the same as the voltages a sor of the 6BE6. Modulation level v:rtput 12AT7 with B- supplied by grid transformer of the transmitter. The is controlled by R4. This control should selenium rectifier. (The 6BE6 may be link winding Ll should be close to the ground end of L2. L2 is tuned by a 117VAC SI trimmer condenser from the i.f. trans- former. CIO I TRIMMER To adjust the receiver and trans- C9I.1 IT1GNDCLIP mitter, plug 12AT7 6BE6 //77 both units in at the same L2 L1 3 -1 100//M77//A REGT point and let them warm up. Closing 6 ir S2 puts the transmitter in operation 1.01, C11.0.0~- CI .01 64 C3.05 R7 2.2K R82100/IW and should close the relay RY on 4-1 6 o ) the receiver at the same time. If it RI R2 IW C6 /.001 HI IMP Af IN C4 2.SMN MICA 20/450V does not, adjust R9 so the relay opens IOMEG RS , 00K 65 IME G ?rR2ME R6 1K/2W .0001 _ LI and closes as the transmitter is turned IO MEG 226 CB.. 40/450V MICA C5 .0001 on and off. Connect a v.t.v.m. (or a 8 450 100 -volt, 10,000- ohm - per -volt meter) T between the R3 476 chassis and the junction of R3 and R4. The voltage (a.v.c.) at Fig. I -Avoid unwanted radiations from the transmitter by keeping the g ound lead short. this point should be several volts. With transmitter and receiver oper- I Capacitors: I -O.I -µf. 600 -volt; 1- 0.1 -µf, 600 -volt; watt, 1 -100 -ohm, I -watt; -I meg volume -control 4- .01 -µf, paper; 1-.001 -, I- .0001 -µf potentiometer. ating, adjust the transmitter frequency mica; I- .0001 -µf, midget variable; I- 20.20 -20.20 -µf, Tubes: I- 12AT7, 616 or 12A %7, I-48E6 or 6SA7. control C5 for maximum 450 -volt elec. (Sprague EL420 or equivalent; three Miseell : I -1.5 -amp. fuse and holder, 1- deflection. sections paralleled for C8 and one section for C7), 455-kc i.f. transformer (modified per text), 2- Adjust, in turn, the trimmers on the 1.2 trons- I -8 -µf, 450 -volt elec. s.p.s.t. toggle switches, I-6.3 -volt, -amp. secondary and primary of T2 for max- Resisters: 2 -10 -meg, I -I -meg; 2- 100,000; 177,000; former, I- 100 -ma selenium rectifier, I-5 x 10 x 3 -inch 1- 22,000 -ohm; I- 2,200 -ohm, I -watt, I -1,000 -ohm, 2- chassis. imum voltage. Touch up the tuning by r 6BF8 SUA BY' adjusting C8 on the receiver and C10 68A6 on the transmitter. GNgCIIP 20/45011/ R2 100 4566C C8-1RIMMERIN IFT rJl C.w. men can control their trans- 5 RI C4/.01 .500 IOOMA SEL RECT mitters by connecting an open- circuit +=. 2 (- . CT /603,IW T 64 TO jack across S2 on the receiver and -11--4 116 47K 6 450V LI .0001 R9 2K 2 2.2 CONTROL plugging in a key. The relay terminals MEG CIRCUIT 5 F MICA are then connected to the keying termi- C4 .01 C5-.1 C3 8 nals on the rig. It may be necessary to 117 VAC .005 IN34 CATH select a fast keying relay for this MICA 2W ap- R3R31. . 100 plication. 100K' FILS II l 04/.01 AF OUT R4 Fig. 2-Do not connect this receiver to a.c: d.c. equipment without observing line polarity. Correction: The botto!n end of the secondary of the 456 -kc transformer should connect to the top of R6. Omit C4 and connect the left -hand side of R7 to the junction of R6 and R4. Capacitors: 3- .005 -, 2- .00001 -, I- .00005 -uf mica; Miscellaneous: I -L5 -amp. fuse and holder, 1-455 - 5- .01µf, I -O.I -µf, 600 -volt paper; I- 20- 20- 20- 20 -0, kc i.f. transformer (modified per text), I- 455 -kc Lf. 450 -volt elec. (Sprague EL420 or equivalent; three output transformer, I- s.p.s.t. toggle switch, 1 -6.3- sections paralleled for C7 and one section for C6). volt, 1.2 -amp. transformer, I- germanium crystal Resistors: 2 -2.2 -meg, I- 100,000 -, 1 -47,000 -, 2-100 - diode, I- sensitive relay (to operate on 5 ma), I- ohm, I- 10,000 -ohm, 2 -watt, 17,700 -ohm, I -watt, 1- 100 -mo selenium rectifier, I-S x 10 x 3 -inch chassis. 470 -ohm, 1 -watt; I-1-meg potentiometer; 1- 2,000- Note: All capacitors are 200 -volt type (or higher ohm wire -wound rheostat. rating) and resistors are 1/2 -watt or larger, except Tubes: I -6BA6, 6SK7 or 6SG7, I -6BF6 or 6SR7. where specified. Transmitter works with a microphone or key. RADIO -ELECTRONICS for Test Instruments 141 Radio -Frequency Ammeter An instrument occasionally needed but rarely available can be built By RUFUS P. TURNER, K6AI with a 1 -ma meter and 1N34 crystal ARADIO - FREQUENCY amme- resistor is connected directly between ter suitable for use over a wide these terminals inside the case, and the frequency range is frequently positive (anode) pigtail of the crystal needed in ham shacks and ex- diode is soldered directly to one input perimental laboratories. It is usually terminal. The negative pigtail is run di- needed most when unavailable. Thermo- rectly to the positive terminal of the couple -type instruments are rather cost- milliammeter. The calibration rheostat ly and sometimes are limited in fre- is mounted in a hole in the back of the quency range. case. The shaft of this rheostat is cut A very satisfactory ammeter, usable down and provided with a sawed slot for at both audio and radio frequencies (in- screwdriver adjustment. cluding ultra -high frequencies), may be The builder must observe carefully built with a regular 0 -1 d.c. milliam- the proper polarities of both the crystal meter, a 1N34 crystal diode, and a few and milliammeter, as shown in the dia- other components from the spare-parts gram. box. It can be calibrated very easily Front view of the meter. Input jacks on top. with an audio oscillator or filament Calibration transformer. It will indicate accurately 1. Temporarily disconnect one end of 0 -1 ampere, a.f. or so r.f., the regular the 1 -ohm resistor from the rest of the 0 -1 -ma meter scale may be employed if circuit. the builder is unable to prepare a spe- 2. Connect a variable a.c. voltage, ad- cial one. justable from 0 to 1 volt, to the input The milliammeter, crystal diode, rheo- terminals. A satisfactory source is an stat, and bypass capacitor shown in the audio oscillator (with output control) diagram comprise a simple wide -fre- set at any frequency between 100 and quency a.c. voltmeter. When the calibra- 1;000 cycles. Another convenient source is tion control set to the proper value is the 21/2 -volt winding of a filament for a given crystal, 1 volt r.m.s. input transformer, with a potentiometer will give full -scale deflection of the across it. meter. 3. Connect a dependable a.c. voltmeter This rectifier -type voltmeter is con- to the input terminals of the instru- nected, in the complete circuit, across a ment. 1 -ohm noninductive resistor, through 4. Set the input signal to exactly 1 which the unknown current flows. By volt and adjust the 300 -ohm rheostat for Calibration control is screwdriver -adjusted. keeping this resistance low, the drop in full -scale milliammeter reading. The the circuit under test will be held to 1 rheostat ordinarily need not be touched volt. after this adjustment unless the crystal IN34 CATH f From Ohm's law, the unknown cur- U diode or meter is replaced or calibration la 2W rent (I) flowing through the 1 -ohm re- rechecked. INPUT TERMINALS NON-INDUCTIVE .005" sistor, is equal to E /R, where E is the 5. Reduce the input voltage in 0.1- CALIBRATION voltage reading of the rectifier voltmeter CONTROL volt steps from 1 volt to zero, noting and R is 1 ohm. Thus the full -scale cur- the corresponding milliammeter read- rent value is 1 ampere. It is necessary ings. Make a calibration curve like the Hookup of the .f. meter is simplicity itself. only to calibrate the voltmeter for direct one shown. It is advisable to plot a com- indications from 0 to 1 volt to have it plete curve, because individual crystal I. indicate 0 to 1 ampere. The unknown characteristics vary. However the graph current flowing through the shunt re- given here may be employed as is, with .9 sistor may be either a.f. or r.f., since tolerable error. .6 the frequency range of the 1N34 diode It will be easier to use the ammeter .7 is 0 cycles to 100 mc. special if a direct -reading meter scale .6 is prepared like the one in the photo. < Easy to construct s An examination of this photograph will o Construction of the instrument is en- show that currents as low as 0.1 ampere .4 tirely The straightforward. author's (100 ma) can be read easily. .3 ammeter (see photos) is built around a 2 -inch milliameter mounted in a small .2 sloping -front metal meter case 3 inches MATERIALS FOR R.F. AMMETER .I high and 3% inches deep. The O .2 .3 .4 .5 .6 .6 .9 I input terminals are insulated pin I -I -ohm. 2 -watt, noninductive resistor; I -300 -ohm, jacks mounted in the top edge of the wire -wound rheostat; I -0-I ma d.c. meter; I -IN34 VOLTS OR AMPERES To crystal diode; I- .005 -µf, mica capacitor; 2- case. insure short leads the shunt terminals; l -meter case. Calibration is roughly linear after 0.1 volt. JANUARY. 1949 42I Test Instruments 'Scope Aid Helps Audio Men This electronic switch places two patterns on the 'scope at the same time for comparison By. ALFRED HAAS THE cathode -ray oscilloscope, most Fig. 1 shows the basic block diagram ments are the grid condenser and re- interesting of all investigation in- of an electronic switch. There are two sistor. The switching frequency has to struments in the electronic field, is input amplifiers, one for each wave. becoming more and more popular. The switching device is a multivibrator Its cost is no longer a bar to its use for that produces a square wave which cuts very good 'scopes are now availablé at off the two amplifiers alternately. In reasonable prices. However, many ex- this way, one wave at a time is trans- perimenters ignore most of its possible mitted to the 'scope. uses. Some rather simple auxiliary Difficulties may arise in synchroniz- equipment, for instance, the electronic ing the 'scope's time -base oscillator. It switch, permits varied applications. is essential to hold this in step with the wave to be observed and not with the TOUT SYNC square wave of the switching device. TERMINALS OF SCOPE For this reason, a synchronizing ampli. INPUT I fier is provided. Its output is applied to the external sync terminals of the TO VERT INPUT 'scope. TERMINALS OF SCOPE Fig. 2 shows the circuit of the elec- Fig. 3 -Rear view of switch shows small size. e6 JT 2 tronic switch. No power supply has been provided, as the unit is to be pow- be variable; this is done by a potenti- Fig. I block diagram of electronic switch. -A ered by the oscilloscope it works with. ometer R8 and a rotary switch SW Suppose there are two waveforms to (Unless the builder is sure his 'scope's which selects C3, C4, or C5. view simultaneously, for example, the filament and medium -voltage supplies As the resultant wave is not suffi- input and output of an amplifier. The will handle the extra load, it might be ciently squared, another 6N7 (V3) is electronic switch makes such viewing better to use a separate power supply. used as a squaring amplifier. The two possible by switching the two waves on -Editor) Five tubes are used. V2 is a triodes are cascaded without any bias, the C -R tube so rapidly that the opera- 6N7 in a cathode- coupled multivibrator the plate resistors being of relatively tor sees both of them at once. circuit. The frequency- determining ele- high value. The well squared output of V3 is fed into the No. 3 grids of the two 6L7 input amplifiers VI. and V4. The 6L7 8N7 6N7 6L7 INPUT AMPL RELAXATION OSC SQUARING AMPL INPUT AMPL e+250V RS R6 RII R12 RIS ITO VERT INPUT CB OF SCOPE C3 C4 CS C , C CI C7. f TT H 4- SW INPUT I INPUT 2 RI RI6 asnre i lelnlR L., e R7 RB R9 R14 1CIO CII C12 RI7 RIB R20 Fig.4- Superimposed waves of same frequency. TRACE SEPARATION control grids are coupled to the input TO EXT SYNC potentiometers. The strong squared TERMINALS 3 OF SCOPE VS 8Q7 pulses on the No. 3 grids drive the o SYNC AMPL tubes alternately to cutoff. As the plate. resistor is common to both of them, the RI, R16 -'/2- megohm potentiometer R18- 50,000 -ohm potentiometer plate current of one tube a time flows R2, RI4-330 ohms, 1/2 watt RI9, R21- 10,000 ohms, /2 watt at R3, R9, RIO, RI3-470,000 ohms, 11/ watt CI, C2, CB, C7, C8, C9 -0.Ig0, 600 -volt paper in it and the output voltage feeds the R4-4,700 ohms, 1/2 watt C3- 500 -µµf mica vertical plates (or amplifier) of the RS, R6, R7, RIS -47,000 ohms, y, watt C4- .002 -µf, 600.volt paper R8- I- megohm potentiometer CS- .01 -0, 600 -volt paper 'scope. RI I, R12- 270,000 ohms, 'h watt CIO, C12 -8 -µf, 450 -volt electrolytic If V1 and V4 operate symmetrically, RI7, R20- 22,000 ohms, I/Z watt CII -O.1 -µf, 600 -volt paper SW- single -circuit, 3 -pole rotary switch the outputs of both will appear at the same place on the screen, is, the Fig. 2 -This five -tube device allows comparison of two waveforms on 'scope at same time. that two waves will be superimposed. Some- RADIO-ELECTRONICS for Test Instruments 143 times -especially if they are almost Fig. 3 shows the rear of the unit. identical -it is difficult to distinguish The placement of parts is not critical. one from the other, so they must be This little unit is easily constructed, separated. R18 is the separation con- and should work immediately. However, trol. When the arm is at the center, here is some advice on getting best re- both 6L7 screens receive the same volt- sults. Suppose the switching frequency age and both tubes operate at the same is exactly twice the signal frequency. point on their ERIe curves. When the The output of VI will be coupled to the slider is moved to one side of center, the C -R tube for half a cycle, and to V4 operating points of the tubes change so for the other half. As the time base is that one becomes higher as the other kept in step with the signal and there- becomes lower. This causes the traces fore with the switch, only half a wave to appear one above the other on the of each will be seen. Therefore it is C -R -tube screen. There is also, of necessary to vary the switching fre- course, some effect on the heights of quency, and to avoid its being an exact the waves, but this can be corrected by multiple or submultiple of the signal frequency. Low frequencies are best examined Fig. 8- Electronic switch measures frequency. at a rather high switching frequency, say 5,000 to 10,000 cycles; for high fre- quencies, a low switching rate is best. That is why three frequency- determin- ing condensers are provided in the cir- cuit of V2. The 1- megohm potenti- ometer is for continuous tuning. Figs. 4 and 5 show how the electronic switch permits comparison of two wave forms. Note how the traces are sep- arated in Fig. 5. In Figs. 6 and 7 two waves of the same frequency but of dif- ferent phase are compared. The phase difference is about 90 degrees. This time (Fig. 7) it may be more interesting to operate on a common base and to com- pare the superimposed traces. 8 9 Fig. 9- Frequency relationships are obvious. Fig. 5-Waves shown in Fig. 4 are separated. Figs. and show how the electronic switch measures frequency. The wave composed of eight cycles; its frequency resetting the input potentiometers Rl composed of three cycles comes from is 8 times 20, or 160 cycles. and R16. the 60 -cycle line. As there are three The repairman or research worker The cathode -follower synchronizing cycles, the time base is running at will find this switch increasingly valu- amplifier V5 is a 6Q7 with the diode 60/3 = 20 cycles. The other wave is able as he becomes accustomed to it. plates unused. Its grid is tied to that of V1 so that the time base is kept in step with signal E1. The cathode of V5 is to be coupled to the synchronizing input of MECHANICAL COUNTERS the oscilloscope. ELECTRONIC circuits are not always result of a complete on -off pulse is the better than equivalent mechanical de- transfer of the F contact from one relay vices. For example, mechanical relays pair to the next. are perfectly satisfactory for counting Ordinarily there must be as many pulses and are much simpler than equiv- relay pairs as pulses to be counted. alent electron -tube circuits, if the pulse With a slightly more complicated sys- frequency is low enough to be followed mechanically and the pulses are strong enough to operate a relay without amplification. Counting relays have been used for many years in telephone and signal work. The very simple and effective TO F CONTACT OF SUCCEEDING RELAY PAIR Molina counter is used in telephone F R O M F N T C T communication. It was invented in 1911 OF PRECEDING RELAY PAIR. PULSING KEY ! Fig. 6 -These am fv o w -ves, same frequency. bÿ E. C. Molina* of the Bell Telephone Laboratories and has been in use ever One pair of relays operates with each pulse. since. It is shown in the schematic. tern the same relays may be used more This is how the Molina counter op- than once, however. In telephone cross- erates: The pulsing key is alternately bar circuits, for example, five relay closed and opened (as in telephone dial- pairs are used to count a maximum of ing) to provide pulses. When it is ten pulses. At the sixth pulse, the first closed, the M relay is grounded at one relay pair operates just as it did at the end. Since the battery is already con- first pulse, etc. nected to the other end, its contact is At the end of the counting sequence, closed. The N relay remains as shown all the locked relays may be released because it now is grounded at each by opening a switch in the battery cir- end. When the key is released, however, cuit. Amateurs and experimenters can this relay does operate, as it is across use this system for control- function the battery in series with M. The net selectors. instead of expensive rotary Fig. 7-Phase difference is now easy to see. Bell Lab Record, July, 1948. steppers. JANUARY, 1949 441 Test Instruments and Analyzer By HAROLD PALLATZ Fig. l -Front of the complete tester and set analyzer. Standard analyzer adapters are used. A special adapter tests acorn tubes. THE lack of a simple, fool -proof and judged by comparing the meter calibrating method has prevented readings with performance curves in a Calibrating tube many servicemen and experiment- tube manual. ers from building their own tube Adapter plugs and cables permit testers presents testers. This set analyzer (Fig. 1), de- making voltage and current measure- problems signed for use with a standard multi - ments on a receiver or amplifier with- that fre- tester, includes both a good, easy -to- out removing it from its cabinet. An- quently prevent con- calibrate tube tester and a point -to- other feature of the analyzer is that point tester. The multitester shown in the multitester can be removed for use structors from build- Fig. 1 is similar to the "Wide-Range when the tube tester or analyzer is not Pocket Tester" described by the author needed. ing their own. This in the August, 1946, issue. Tubes are The unit can also be used to isolate tested under normal operating voltages a.c. -d.c. sets from the line. Its power tube checker is easy supply delivers 50, 100, 200, 300, and to calibrate because 400 volts d.c. at 90 ma as well as 15 standard a.c. filament voltages to ter- tube performance minals, where they are available for test purposes. figures are com- The basic circuit of the tube tester is shown in Fig. 2. Normal operating pared with those potentials are applied to the elements of the tube. The current through the given in tube man- plate circuit depends on the voltages uals. It uses a stand- and the setting of the load resistor. Measurements are made first with 3 ard multimeter re- volts bias on the control grid. The plate movable current rises when the switch is for outside Fig. 2 -A basic mutual- conductance checker. pressed to short the grid to cathode. radio service calls. RADIO -ELECTRONICS for Test Instruments. 45 The two plate -current readings are then shown on the diagram.) The primary Use a minimum of flux on the connec- compared to the plate- current charac- of the filament transformer (T2) is tions because insulating surfaces are teristic in the tube manual. tapped for 105, 115, and 120 volts. Sep- likely to break down when contaminated The circuit of thee -analyzer (Fig. 3) arate switches are used for each tap. with flux. (Carbon tetrachloride and a is simplified by omitting the wiring of The power transformer primary is small brush are handy for removing all but one of the tube tester sockets. across the 115 -volt tap on the filament excess flux from soldered joints. - The unit includes all standard tube transformer. Autotransformer keeps in- Editor) Sockets. All socket pins having the same put to the plate transformer constant. RMA pin number are tied together and The 50,000 -ohm load resistor R10 is Operating the tester connected to corresponding contacts on a compromise value, suitable for most 1. Plug the leads of the multitester S16, S17, S18, S19, S20, one deck of tubes. To test a tube with a load re- into the A.C. VOLTS terminals and set the S22, and the fixed contacts on Si sistance higher than 50,000 ohms, insert meter to the a.c. volts range correspond- through S10. The nine -prong analyzer additional resistance in series with the ing to the filament voltage of the tube socket connects to contacts on the re- positive side of the meter. being tested. maining deck of S22 and to :the arms of 2. Make sure that the D.C. VOLTS Si through S10. This system of switch- Construction switch is in an off position and the ing provides for testing newly de- The analyzer is built in three sec- ANALYZE -TUBE TEST switch is in the veloped tubes, regardless of their pin tions: the switches, sockets, pin jacks, ANALYZE position. Refer to a tube man- connections. and indicators are on the panel; the ual and adjust the plate, cathode, A standard tube- tester transformer power supply on a subdeck (Fig. 5); screen -grid, control -grid, and filament supplies ,filament or heater voltages for and the multitester fits in a hole cut in switches to positions corresponding to the tubes under test. Plate and screen - the panel. Wire all components on the the pin numbers of the elements. Be grid voltages are supplied by a 400 -volt, panel before wiring the power -supply sure that both filament switches are 90 -ma supply with a voltage divider. chassis. The miniature sockets are con- not turned to the sanie number. (The large tapped resistor, Fig. 4, has nected with fine wire, about No. 22 3. Plug in the tube and set the A.C. since been replaced with a network of enamelled, and the other connections VOLTS switch for its correct filament series resistors R1 through R6 as are made with push -back wire. voltage. (Continued on next page) POLARITY SW ANALYZER SOCKET TUBE TESTER SOCKET o-- METER (ANALYZER) 4 6_ vS23o- 8 METER I I 2 s = 2 PLATE -o S2 4 3 1SI7 4 4 o4 5 4 of 10 OTHER SOCKET 6 4 6 7 MINIM 7 METER 84 1111.- 8(TUBE TEST ) 9 9 o 10 4 w111111111 10 + en e12 IIIIIIiI FIL (LEFT HAND/ CH LOAD RIO I -*I S22 le. TI 80 400V --04 -o A,. fEr>T SIB 2 . 3CONLGRID RI 300V SCREEN --o3 3v- o4SI9 RI 3V - 04 4 o R2 SIS DCV 5 250V II -5 50 6 6 e6 6o R.200V - 7 7 70 ?C ` RI 519 --el I00V 8 8 -a8 8e R5050V T C3 90 09 CATHODE 09 9e )1 010 - R6 10e IMO 10o OFf - -f- Ile oil ell Ile (o}- 120 012 (OFF) FIL (RIGHT HAND) DC VOLTS T2 15Vo °e,0.--0 85V g 70V 514 ACV o 521° ANALYZE 00, 35V ` CI g 30V ¡TUBE TEST 105V 25V SII SPST SWITCHES SI THROUGH 510 115V ó 12.6V_ 10 0o. 7.5V0 ó 6.3V O 1111111 513 1111 G 5V AC VOLTS 11111 g 3.3V o~o 1111 S 2.5V_ 11 S 2V 1 e 1.4V OFF. Fig. 3- Circuit of the tester and set analyzer sections. The meter circuit is not shown. CI- ,01 -1d, 600 -volt paper C2 -dual 8 -0, 600 -volt electrolytic s.p.s.t. slide or toggle switch 524-s.p.s.t. push -button switch C3-16-0, 600 -volt electrolytic 514-24 -point rotary tap switch, nonshorting TI -power transformer, 760 volts c.t., 90 r^a, 5 volts, RI, R4 -2,500 ohms, 10 watts S15-11-point rotary top switch, nonshorting, with 2 amps., 6.3 volts, 3 amps. R2, R3, R5, R6-1,300 ohms, 5 wafts stop T2- filament transformer, 105 -, 115 -, 123 -volt primary; R7- 22,000 ohms. 1/2 watt S16, S17, SIB, 519, 520-12 -point rotary switches, non- secondary tapped at 1.4, 2, 2.5, 3.3, 5, 6.3, 7.5, R8-470,000 ohms, Vs watt shorting type 12.6, 25, 30, 35, 50, 70, 85, and IÌ5 volts. May be R9- 1000000 ohms, /, watt 521- s.p.s.t. toggle switch Stancor P- 1834 -3 or equivalent R10- 50,000 -ohm 4 -watt, wire -wound potentiometer S22 -2 -gong, 11 -point rotary switch, nonshorting CH-8 h, 100 ma SI. S2, 53, 54, 55, 56, S7, 58, 59, S10, SII, 512, 513 - S23-d.p.d.t. Toggle switch NE: -I /10 -watt neon lamp JANUARY, 1949 Test Instruments 461 4. Turn on the power, using the of rectifiers and diode detectors can 1. Turn off the power and rotate all switch corresponding to prevailing line vary as much as 40% without making switches to the off position. Throw the voltage. If the filament voltage is too replacement necessary. Oscillator and ANALYZE -TUBE TEST switch to ANALYZE. low, open the switch and close one converter tubes should be replaced when 2. Remove the tube from the stage in marked for lower voltage. If too high, the current drops 10% or more. Discard the amplifier or radio where measure- use a high -voltage switch. Do not close amplifier tubes when the indication is ments are to be made, and insert it in more than one power switch at the same 20% below normal. the proper socket in the tester. time. Experience testing a few tubes with 3. Plug one end of the adapter cable this unit will show when a tube has into the vacant tube socket and the reached the end of its useful life. other end into the nine -prong analyzer Short tests are made by substituting socket on the panel. the neon indicator lamp for the plate - 4. Set the multitester to the 300-ma current meter. Set the D.C. VOLTS control range and plug the meter leads in the to 100 volts and turn the PLATE switch METER terminals in the center of the to the number corresponding to the panel. cathode pin. Rotate the CATHODE switch 5. Open the toggle switch correspond- to all positions. The indicator glows ing to the pin number of the circuit. when there is a short between the Turn the left -hand FILAMENT switch Fig. 4 -The bleeder and acorn -tube adapter. cathode and one of the elements. S22 to the number of the circuit being 5. Remove meter leads from A.C. To check shorts between other ele- metered. VOLTS terminals and insert them in the ments, set the PLATE and CATHODE 6. Turn on the power in the set. Press METER terminals on the left side of the switches to pin numbers corresponding the push- button METER switch to obtain panel. From the tube manual, determine to the questionable elements. The PLATE a current reading. If the meter reads the zero -bias plate current for a given switch is set to the element operating backward, throw the polarity switch in plate voltage and load. Set the meter to nearest cathode potential. the opposite direction. If necessary, set a direct -current range that will pass Transconductance tests can be made the meter to a lower range so the cur- this current safely. by dividing by 3 the change in current rent falls about mid -scale. 6. Adjust the D.C. VOLTS switch and produced by removing grid bias and To measure voltage, use the CATHODE LOAD control to the desired voltage and multiplying the resultant by 1,000,000. switch and the right -hand FILAMENT load resistance. (Reading of the LOAD The product is the transconductance of switch S20. dial multiplied by 500 gives the value of the tube in micromhos. 1. Turn all rotary switches to the the load resistance.) Note the plate cur- OFF position. rent on the meter, then turn the CON- Using the analyzer 2. Connect a jumper between the TROL GRID switch to the off (No. 12) Point -to -point voltage and current chassis, or $- minus, of the set and the position. The new current reading is measurements can be made on a radio ground terminal on the panel. for zero bias. or amplifier without removing the chas- 3. Set the right -hand filament switch 7. Compare the two current readings sis from the cabinet. Connections are to the number of the circuit being with those listed on the characteristic made to the meter through the analyzer metered. curve in the tube manual. If the meas- cable and the adapters. These measure- 4. If the voltage measurement is ured currents correspond to those in ments are confined to low- frequency made with reference to the cathode; set the manual, the tube is assumed to be radio circuits and audio and power cir- the CATHODE switch to the number of good. The permissible deviation from cuits since the capacitance of the cable the cathode pin. If the voltage is made normal values depends on the type of affects high -frequency circuits. To between an element and ground, set the tube and its application. Plate current measure current: CATHODE switch to 10. 5. Press the METER switch to read voltage. (Note that no provisions are made for tubes with the suppressor brought out to a separate pin. With prevailing tube types the suppressor can be left floating. If it is desirable to connect the suppressor to the cathode or other ele- ment, plug a jumper into the cathode and suppressor pins on an unused socket.) Other applications Filament voltages are available for test purposes by plugging leads into the A.C. VOLTS terminals and setting the A.C. VOLTS switch to the required volt- age. D.c. voltages are available at the D.C. VOLTS terminals. The voltage is de- termined by setting the D.C. VOLTS switch. A special adapter is used for isolating a.c. -d.c. equipment from the line. The adapter is a female plug mounted inside a five -prong tube base. Terminals of the plug are wired to pins 1 and 5 on the tube base. Plug the adapter into the five -prong socket, set the filament switches to 1 and 5, and turn the A.C. VOLTS switch to 115 volts. Intermit- tents and faulty oscillators can be lo- Fig. 5- Behind -the -panel wiring is shown. cated by lowering or raising the voltage The power supply is on the sub -deck. with the A.C. VOLTS switch. RADIO -ELECTRONICS for Audio I47 II What is Supersonic Bias? This clearly written article takes the mystery out of a common, but not well- understood, term 000 by DR. ANGELO MONTANI* ALTHOUGH of mag- of turns per inch. first slug and compare all the rest to netic recording was started If 0.1 ampere flows through the coil that. We find that the second slug, mag- many decades ago, only recent- of Fig. 1, the value of H would be 0.1 X netized under a current of .02 ampere ly is it proving to be a real 10,000 = 1,000. (H is often referred to (when H was 200), has a H. value of, threat to disc recording. Wire and tape in textbooks as the magnetomotive force not 200, but 300. Table 1 (next page) recording are increasing in popularity gradient.) shows B, vs coil current for all ten bars. so fast that every radioman -and espe- Suppose we take ten cylindrical steel - From Table 1 we make the upper cially every radio serviceman- should alloy slugs, each 1 inch long and of the right or positive portion of the graph of learn the fundamentals of the process correct diameter to fit inside the coil. Fig. 2. The horizontal (X) axis is as soon and as thoroughly as he can. We place one in the core and apply the marked off in H units rather than cur- Supersonic bias is a familiar term battery voltage necessary to produce a rent. The vertical (Y) axis shows the today in the sound field because all mag- current of .01 ampere. We remove the same B, figures as the table. first slug and substitute the second. This If the current in the coil had been i- I Iwo TURNS -Al time we energize the coil with .02 am- made to flow in the opposite direction, pere. We continue the procedure with the slugs would have been magnetized the remaining eight slugs, increasing to the same extent, though their polari- ÌÌÌÌÌiÌÌiiÌÌi(! .*CENTER HOLE the current each time by .01 ampere. At ties would be reversed -the north and ...l.,I,.Il..l., FOR SLUGS the end of the process we have ten per- south poles would have changed places. manent magnets. Next we measure the residual mag- DIRECTION OF TRAVEL OF MAGNETIC MEDIUM netization, that is, the amount of per- manent magnetism, left in each slug as the result of its exposure to the electro- RECORDING HEAD magnetic coil. We find that this flux t 'sFr F+tl it-'t density (represented as B,) is not pro- Fig. I -Setup for experimental magnetization. portional to the current which caused it. To determine the relationship between netic recorders use it. But do you know +It MIKE just what it is, why it is used, and how Fig. 3 -How the signals are recorded on wire. it works? Every radioman knows that a steel needle, for example, can be magnetized Because of this, we can reproduce the unman/ original positive curve in the negative permanently if it is touched to an ordi- nary bar or horseshoe magnet. It will 111/111111 direction, using the same figures, but also be magnetized if it is placed inside preceded by minus signs. The symmetri- a coil energized by 111111111 cal result, shown in Fig. 2, is known as d.c. the complete Such a coil is shown in Fig. 1. The retentivity curve. It gives 'SII I/Illlllll us sufficient data for an coil is 1 inch long and wound with understanding 10,000 turns of thin Nipper wire. When M of magnetic recording and supersonic a battery is connected to the coil, a mag- bias (sometimes called radio bias). netomotive force appears along its In magnetic recording, H on the graph represents length. This force, measured in ampere - the instantaneous val- ues of audio current flowing turns, is referred to as m.m.f. It is the 550 through the product of the current through the coil recording -head coil. The H signal is (in amperes) times the number of 760 analogous to the grid signal of a vac- turns. uum tube. The corresponding B, values -KM -1050 represent the output -what is placed on In measuring and evaluating the 1010 -100 the tape -and is analogous to a vacuum magnetic characteristics of specific ma- - A20 - er tube's plate current. This analogy be- terials, a more convenient way to refer Fig. 2- Magnetization curve plots Br versus H. to magnetic field intensity is in ampere- tween the magnetic B, -H curve and the turns inch, Er I curve of a vacuum -tube amplifier per represented by the letter the coil and H. This current the retained flux is very helpful in understanding super- is the product of the coil cur- B, of each we rent (still in amperes) and the number slug, assign an arbitrary sonic bias. value of 100 to the retained flux of the Fig. 3 shows a magnetic recording Chief Engineer, W. M. Instrument Corp. JANUARY. 1949 481 head schematically. The particular one one of the points indicated by the dashed at any instant and therefore cannot pictured is the split -ring type, the most lines in Fig. 5. cancel completely. common. The gaps between the two half - Magnetic bias has disadvantages, and What remains on the wire or tape rings are about .001 inch, and each half - is now of purely historical interest. Any (the difference between the two dis- ring is made of stacked laminations of mechanical vibration is recorded as torted signals) is an undistorted signal high -permeability alloy. The magnetic noise. And the linear portion of the of the same form and frequency as the medium (wire or tape) passes the up- curve is so limited that the dynamic original audio before the supersonic per gap at a constant speed. At each range is insufficient for music. bias was added. instant a .001 -inch section of the tape Supersonic bias was first introduced This last statement may sound as about a of a century ago. though it in RECORDING quarter It were "dragged by the .001 GAP of a of .020r_LAMINATIONS consists current superaudible horns," but it can be proved by going frequency which is fed to the recording back to simple mathematics. We stated .006 GROOVE head along with the audio. The usual that the algebraic difference between frequency is approximately 50 kc. Fig. the two distorted recorded signals at 6 shows the audio, the supersonic, and any instant yields an undistorted wave. WIRE DIA.003 .DOS the combined waves. The statement is correct as long as the Note well that the audio does not portion of the opposite of branches of the modulate the supersonic signal, but com- magnetic curve to which we apply the COIL COIL bines with it, the resultant combined two simultaneous a.f. profiles is either LAMINATIONS wave being a vectorial addition of the straight or parabolic. That is because the difference between the correspond- ing points of any symmetrically oppo- Fig. 4-View of a magnetic recording head. TWO IDENTICAL site parabolas (or straight lines) is a AF PROFILES straight line. or wire is across the gap and a tiny This law is commonly used in class -B magnet is formed. The recorded sound amplifiers, as shown in Fig. 8. The au- consists of these minute longitudinal AF TO RE AF AND SUPERSONIC COMBINED dio is applied to both tubes at the same magnets, the flux and polarity of each RECORDED SUPERSONIC FREQUENCY time, producing two distorted outputs. depending on the current in the coil at Fig. 6- Supersonic bias uperimposed on a.f. Because the E, -I curves of the two the instant the magnet was made. tubes are equally and oppositely non- Fig. 4 gives a somewhat better idea linear near the zero point, the resultant of the construction an two. For this reason, two in -phase au- of actual record- dio are formed, one on either output is undistorted. ing head. To profiles show the parts more clear- side of the supersonic frequency, rather ly the Eylp dimensions in the drawing are than the familiar out -of -phase modula- much out (VI) DISTORTED CURRENTS OF INDIVIDUAL of scale. This particular head tion envelope. We might say that the TUBES is suitable for wire recording only; the is into two top groove audio signal split identical, would be somewhat different in -phase audio signals. Actually, the 1 11 for tape. original audio frequency is shifted back EE-Ir _ ,-- 1 and forth with twice the amplitude of (vz) the supersonic frequency at the super- t. UNDISTORTED OUTPUT CURRENT (DIFFERENCE) sonic rate; but this is, of course, inau- dible. The composite wave is now applied to Fig. 8- Class -B amplifier distortion cancels. the magnetic retentivity curve previous- ly described. The result is shown in Fig. In the class -B amplifier the over -all 7. One audio profile is applied to the curve is already split at the zero point, t negative portion of the curve and the since two tubes are used. In magnetic other to the positive portion. Each pro- recording, the retentivity curve cannot, file results in a distorted output. The two of course, be split, so supersonic bias is Sm distorted output signals, however, are ZERO BIAS LINE of opposite polarity and subtract from each other. The distortion components TABLE 1 TEADY BIAS Coil Cur- Retained -Br i Br Slugs rent (amps.) Flux (B,) Fig. 5- Signal zeroed at center is distorted. 1 .01 100 DISTORTED AF OUTPUT 2 .02 300 The arrangement of Fig. 3 can be 3 .03 550 used for making recordings, but the dis- 4 .04 760 tortion would be very pronounced. Fig. 5 .05 900 5 (the B, -H curve is a copy of that in 6 .06 1000 Fig. 2) helps to show the reason. This UNDISTORTED AF OUTPUT. 7 .07 1050 (DIFFERENCE) is where the analogy with the vacuum - 8 .08 1090 tube E5-I curve is useful. Employing 9 .09 1110 vacuum -tube graphical technique, we DISTORTED AF OUTPUT 10 .1 1120 draw a sinusoidal input signal S,,, and then construct a corresponding output used to produce two audio signals. By signal S,,,,,. Sou, is obviously badly dis- controlling the amplitude of the super- due to B Br torted, the curvature of the H AF AND SUPERSONIC sonic bias, the two a.f. waves can be characteristic in the vicinity of the zero centered on the most parabolic sections point. Fig. 7- Resultant output wave is undistorted. of the curve. Early experimenters realized that the We believe that the reader is now in input signal should be centered, not at in each output signal are equal and op- the position of appreciating fully the the zero point, as in Fig. 5, but some- posite in polarity, so they cancel, and neat trick performed with supersonic where on the straightest portion of the the resultant is an undistorted signal. bias. It is without doubt a genial and magnetic curve. A steady magnetic bias Though the resultant has lower ampli- elegant solution of the problem of ob- analogous to the d.c. grid bias of a vac- tude than either of the distorted signals, taining a virtual or phantom transfer uum tube had to be superimposed on it is not zero because the amplitudes of line which is straight, out of the the a.f. signal so as to shift its axis to the two distorted signals are never equal crooked retentivity curve. RADIO- ELECTRONICS for Foreign Newa 149 European Report By Major Ralph W. Hallows RADIO -ELECTRONICS LONDON CORRESPONDENT done here by the BBC and the British records of the cathode -ray tube screens Electrical and Allied Industries Re- are made at regular intervals, and search Association -let's shorten that listener- response curves are easily pre- one to BEAIRA. Well, BEAIRA con- pared from these. ducted two sets of tests on a range of The scheme has, of course, several frequencies between 40 and 100 mc, limitations. A separate recorder is re- IT'S not so very using a vertical dipole antenna for quired for the circuits served by each long since the reception. The antenna was sited a few supply transformer; that, though, is only insulating yards from a road along which vehicles not altogether a disadvantage, for it materials from of different kinds were driven. The enables the response of particular which molded or results show that the interference has districts to be metered. The recorder extruded radio a sharp peak a little below 59 mc and can't discriminate between the stations parts, such as tube sockets, coil forms, that in the region of 90 -100 mc it may to which radios are tuned; all it can and panels were made of bakelite be down by nearly 20 db. The latest indicate is that so many are in use. and hard rubber. The use of higher and BBC field tests largely confirm these higher frequencies made new insulators findings and add other interesting de- Wanted, an ECC with far superior qualities essential tails. It is found, for instance, that Would that we had in Europe a body and the chemists gave us such won- horizontally polarized v.h.f. transmis- as effective for the whole continent as derful stuff as polyvinyl chloride sions are much less affected by ignition your FCC is for the United States! (P. V. C.) and the polyethylene fam- interference than those vertically polar- The channels allotted to our stations ily. The latest offspring of this family ized; that much smaller signal field are mainly a matter of international has just come into use in Britain. It is strengths are needed at 90 than at 45 negotiation and agreement. There is polytetrafluoroethylene -a pretty little mc to override such interference; and nothing to compel all countries to come name, but perhaps rather too long for that hardly any interference is caused into line and even if all sign the terms general use in these busy days. We call by vehicles whose ignition systems have of an agreement, such as that on which it P.T.F.E. for short. It seems to have been suppressed with a resistor in the the new Copenhagen Plan (due to come most high- frequency insulator virtues main distributor lead. into force March 15th, 1950) is based, and few, if any, of the vices. Its prop- Another finding of interest to folk no means exists of enforcing strict erties are unaffected by oils, alkalis and on both sides of the Atlantic is that compliance in countries where broad- most acids; it doesn't soften or warp interference with television signals on casting regulations are father vague. when heated; it has a low coefficient the 45 -mc band (results on the 90 -mc The report on frequency measurements of expansion; it has so much resilience band are not available) is considerably during a recent month, for instance, that it doesn't tend to crack even under more severe with horizontal polariza- shows that though 181 European sta- prolonged and severe vibration. At tion than with vertical. This surprised tions deviated by less than 5 cycles present it's being used mainly for co- me a lot, for I know that many, if not from their allotted frequencies, there axial and other r.f. cable connectors, all, American television transmissions were 84 whose frequency wanderings for connectors for hermetically sealed have horizontal polarization, whereas exceeded 25 kilocycles! In the first class components and for the sockets of min- ours have vertical. Yet I've seen very there were 17 French stations and in iature tubes. At the moment it's prob- few references to this nuisance in U. S. the second 11. Realizing the chaos which ably the best insulator available for journals, though it crops up constantly such errings and strayings can and a wide variety of purposes; but no in British ones. do cause, you'll see why I wish so doubt something with an even longer fervently that there could be a Euro- name and still more virtues will appear Listener -Interest Meter pean counterpart of the FCC armed before we are much older. The magazine published by the In- with equal powers. ternational Broadcasting Association Automobile Ignition Interference reports the development in Denmark Though all of us heartily cuss the of an ingenious method of making di- effects of auto ignition interference on rect measurements of listener response our reception of television and other to broadcasts. The essence of the in- v.h.f. transmissions, the amount of data vention (which, whatever might be obtained either in the U. S. and in thought at first sight, does not belong Britain on the exact nature of this to Mr. Gernsback's April First class) interference seems surprisingly small. is this: when a receiving, set is switched We know by experience that it is usu- into an a.c. supply circuit, there is a ally imperceptible on the broadcast slight distortion of the supply wave band, becomes a nuisance at frequencies form, owing to the action of the rectifier above about 3 mc, and is something of the radio. The distortion is small, more than a nuisance above 30 me. but it is cumulative and the resulting Has it a peak frequency? Is there a harmonics introduced can be made to frequency above which, like natural take the form of a voltage proportional static, it has negligible effects? Are to the number of radios in use at any its effects worse on horizontally or time. By using a calibrated cathode - vertically polarized transmissions? ray oscillograph, the number of receiv- Those are questions to which answers ing sets in action can be measured are needed and can't be found in the directly. The system isn't just a mat- Suggested by N text books. ter of theory; it has been in use for J. Beaulieu. Montreal, Canada Two good bits of work have been some months in Denmark. Photographic "But you said you could fix shorts!" JANUARY, 1949 sol Servicing Improving Supply To Test Car Sets Photo I -This is origi- S. LEEPER nal battery eliminator. By HARRY MANY battery eliminators used lamp bulbs in series with the primary in service shops to furnish of the eliminator transformer, a vari- 6 volts d.c. for testing car and able rheostat was installed in the pri- some farm radios have no mary circuit to control the output volt- means of regulating the output voltage age. A voltmeter across the output was or checking the voltage applied to the necessary. Since an ammeter in the d.c. set or the current it draws. circuit often gives clues to radio de- An eliminator with a copper -oxide fects, one was added. rectifier is shown, as originally pur- A wire -wound, 150 -ohm, 150 -watt chased, in photos 1 and 2. The original rheostat was used in the eliminator pri- wiring of the eliminator is shown in the mary circuit. A lower- wattage rheostat schematic. could probably have been used, but the This eliminator is rated at 6 volts ratings of all rheostats decrease when output with a 15- ampere load. With the enclosed in a case. A lower resistance original arrangement the voltage would could have been used to drop the output be too high with the light load of most to 6 volts with most radios, but the 150 - radios. ohm rheostat makes it possible to drop After experimenting with various to 4 volts. A 0 -15 -volt meter was used across the output and a 0 -25- ampere meter was selected because the output circuit Photo 4-New components are on panel. SW REGI CR of the original switch if desired, as the a location on one end of the case RTVAC latter's C DC OUTPUT interferes with standing the case on RECT 2 end. Eliminator, when purchased, has this circuit. Photo 7 shows the revamped elimina- is fused at 25 amperes. (Fuse is not shown in diagrams.) A 117 -volt pilot -lamp mounting was also obtained, as well as a spare switch Photo 2 -Rear view shows original parts. for the input circuit. All this equip- ment was made ready for mounting on the top panel cover, or lid, of the elimi- nator case. The parts are shown in photo 3, to- gether with the top panel, which has been drilled and in which the required circular openings have been cut. Photo 4 shows the panel with the parts assembled, while photo 5 is a rear view. The wiring shown in the second dia- gram was then completed. Photo 6 shows the flexible wire used, making it easy partially to remove the top panel in case the fuse blows. The spare toggle switch installed was Photo 3 -Drill holes in panel for new parts. not wired, but can be connected in place Photo 5 -Rear view shows parts ready to wire. RADIO -ELECTRONICS for Servicing nt.:., .: Photo 8- Output: 9 volts; current: 6 amperes. Photo 9- Output: 6 volts; current; 5 amperes. Photo 6- Flexible wire makes assembly simple. current about 6 amperes. The rheostat was then adjusted as in photo 9 to give a normal output of slightly over 6 volts. The ammeter then shows less than 5 amperes. With the rheostat thus adjusted, the radio's buffer condenser was bypassed with a resistor -to duplicate a par- tially shorted condenser -with the re- sults shown in photo 10. High current with low voltage is indicated, infor- mation which makes the meters worth- while. Photo 10- Readings show effect of bad buffer. Photo 11 illustrates a condition where the rheostat is adjusted -with the radio apparently normal -to place an ex- tremely low voltage (about 4 volts) on the radio. This treatment may often give an Photo I I- Reduced voltage tests the vibrator. J The complete, revamped circuit appears here. indicatión of the condition of vibra- Photo 7- Supply is connected the to a cor radio. tor; one with worn points usually will R- ISO-ohm, ISO -watt rheostat not start on this voltage unless tor in PL- 117-volt pilot lamp jarred. operation. It is connected to an SW- S.p.s.t. toggle switch A weak OZ4 rectifier tube may also be T- Step -down ordinary car radio and the rheostat is transformer detected by lowering the voltage adjusted RECI, REC2- Dry -disc rectifiers below for practically zero resistance. CH- Filter choke normal, and other defects may be noted The closeup view in photo 8 shows that C- Filter capacitor by raising or lowering the voltage and the output is Ml-0-2S-amp. meter around 9 volts and the M2 -O -IS -volt meter watching the meter indications. NEW YORK SERVICEMEN FORM STATE FEDERATION Radio and television service tech- that their associations could, through annual meeting, which is to be held in nicians of New York State met October a federation, act more effectively to April, 1949. The first permanent officers 31 at Binghamton to establish the state raise the technical level of their mem- are: Lawrence Raymo (president, Ra- federation of radio servicemen, which bership by sponsoring lecture tours, and dio Technicians Guild, Rochester), was formed temporarily at Rochester could act in matters concerning state president; Max Leibowitz (president, on October 10. The meeting was at- legislation better than could any of the Associated Radio- Television Servicemen tended by about 35 persons, includ- local associations acting alone. A state of New York ing City), vice -president; representatives from Binghamton, federation would also have advantages Wayne Shaw (president, Radio Service- Ithaca, New York City, Poughkeepsie, in carrying on educational campaigns men's Association and of Binghamton), sec- Rochester. It was arranged by the among the public and is in a better retary; Ben De Young (president, Cen- Radio Servicemen's Association of position to encourage formation of new tral New York Radio Technicians Binghamton, which acted as host to the associations. Guild), treasurer; delegates and Evart M. Hol- from the various local groups. Each association will send two dele- land (president, Hudson Valley Radio A statement of aims and objectives gates to Federation meetings. At pres- Servicemen's Association), Sergeant - was made and rules which will serve as ent, one of the two delegates also serves at -Arms. the basis of a future constitution were on the board of directors. Meetings will Federation headquarters was estab- laid down. The objectives of the new be held several times a year. Dues at lished Empire at the address of the secretary, State Federation of Electronic $20 a year for each association was set, Wayne Shaw, 392 Chenango St., Bing- Technicians Associations are to pro- and it was decided that meetings should hamton, N. Y. The mote first efforts of the fellowship and cooperation among be rotated among the various cities Federation will he to assist technicians servicing groups and better cooperation which have member associations. or groups of technicians who wish to between the repair industry and the Officers and a board of directors were form their own local associations in any general public. Delegates pointed out elected. They will serve until the first part of New York State. JANUARY, 1949 Servicing 521 Using Your Ohmmeter How to use a volt- ohmmeter, a tube hand- book, and intelligence to service a set By HERBERT S. BRIER, W9EGQ RADIO experimenters are frequent- each issue of RADIO- ELECTRONICS. A Plug the set into the power line to ly asked to repair broadcast re- significant fact emerges: no matter see if it is actually defective and (as- ceivers for the neighbors. Often, what the circuit, the components associ- suming it is transformerless) if the for diplomatic reasons, it is un- ated with a given type of tube are tubes light. If not, remove the power wise to refuse (for example, when your startlingly similar. Recalling that the plug and, using the tube manual to antenna is tied to the asker's chimney). serviceman's job is to detect and replace identify the correct terminals, test each And servicing broadcast receivers can defective parts, the worth of a tube filament in turn for continuity. Replace help make one's hobby self- supporting. manual as a service tool begins to ap- burned -out tubes and pilot bulbs. If all Most experimenters say, "I'd like to, pear. With it, a volt- ohmmeter, and a filaments show continuity, test the a.c. but I have neither test equipment nor small stock of parts, all a.c. -d.c. receiv- switch and cord. If they are good, plug service manuals." ers and over 90% of all others can be in the set again and, using the 150 -volt Have you ever watched a skilled speedily serviced. a.c. scale, put the meter across each serviceman at work? You may have no- filament. The meter will indicate when ticed that he used his volt- ohmmeter Finding the trouble it is across a filament that may not open more than all the rest of his equipment until power is applied to it. combined. This meter makes an excel- Now the set is on the bench and if Caution: When working on a trans - lent substitute for more elaborate test you have asked a few questions, you formerless set which is connected to the equipment. have a fair idea of what is wrong with power line, always put it on a piece of Finding a substitute for service man- it before you touch it. insulating material and be very careful uals seems a difficult task; but is it? Did it suddenly stop working? Prob- about what you touch, because it is very The aim of a serviceman is to detect ably a burned -out tube, shorted con- possible to get a shock, even with the and feplace defective parts, not to re- denser, or open resistor. switch off. wire the receiver. A complete diagram Did the volume get weaker and weak- In most a.c. -d.c. sets, the total of the is seldom required to service it. The er, the receiver finally failing complete- filament voltages in series equals the vacuum tube is the heart of any piece ly? Probably weak tubes. line voltage, but in some a resistor, of radio equipment, so let us examine Does it play normally for a time, then often in the form of a resistance line a good tube manual. cut out? Could be almost anything. cord, or resistance tube, dissipates the There is page after page of tube Does it have excessive hum or difference between the two voltages. An characteristics, with application notes squeals? Probably the electrolytic filter open line cord can sometimes be re- for each tube. Socket connections and condensers have dried out. paired, but it is usually more satisfac- voltage ratings interest us most. Has anyone else worked on the re- tory to replace it with a new one. Th( The end pages of the manual list ceiver? More than one baffling bug has correct resistance is calculated by mean: typical circuit diagrams with suggested been caused by someone's having re- of Ohm's Law : E = IR. The difference parts values. Examine these circuits and moved several tubes and replaced them between the line voltage -and the com- those appearing on the circuit pages of in the wrong sockets. bined filament voltages equals the re- quired voltage drop and the current i: EXT ANT that of a single tube. Assume the line e 12SA7/12BE6 12SK7 /12BA6 12SQ7/12A16 50L6/5005 voltage is 120, the filament voltage:: - ^r^ OSCMIXER IF 2ND DETAVCISTAUDIO OUTPUT , -,0k 0.15 total '75, and the current is ampere:. +60-80V +60-80v IFT .005-.05 +80 -100V (,02 (80w IFT (80v) +5-50 COI) (100V) 120 minus 75 equals 45 volts drop, am. 45/0.15 equals 300 ohms, the require(. 1 resistance. Aft If the tubes light, measure the d.c. +60- BOV TUNING IMEC `T 270K- voltage and the resistance between rec- -1- -3V roV (80V) iJry 47oK GANG\ 5V cathode and circuit ground. Th,: 10N- 50K 5001(... C (.0D .005 (470K) tifier 01 \ 120K) ( 500K .05 voltage should be approximately 100 .25 R 050 I-2MEG (IMEG) 2-IOMEG resistance several thousand .I(.I) \ . 4_ (I) .0001- and the .01- ./ 101 -.25(.I) .0005 (SMEG) ohms minimum. Low voltage and normal (.00025 ) resistance indicate a defective rectifier. B Low voltage and low resistance point to a short circuit. Use the ohmmeter t3 BO- 100v 6.3V/.ISA PL (100V) look for blown filter and bypass con- This is a diagram of a typical a.c.-d.c. re- densers. It may be necessary to un- 35Z5 -GT/ 60 -80V 35W4 (80V) ceiver. The range of values for each compon- solder one lead of a suspected one be- ent is shown, and, in parentheses, the value CHASSIS 35256T 12SA/ fore a definite decision about its condi- 100V most commonly found. Though a diagram of 5005 f 12SK7 tion can be made. When the short has the actual set being serviced is helpful, tricks measure d.c. volt- 47I00 1,, and unusual circuits are not often found and been eliminated, the 12507/ (41) T20-100T 117VAC/DC .01:05(.02) age again. Even a momentary short cir- 150) 1 this diagram will usually serve. Trouble may be < found in any portion of the set where meter cuit often damages the rectifier perma- .01-.1 (.OS VALUES IN PARENTHESES ARE MOST US 0 ONES readings vary greatly from values shown. nently. RADIO -ELECTRONICS for Serriciny 153 Proper voltage at the rectifier and move and tap components while the re- nal or noise. (This will work pnly on a none at a tube element which the tube ceiver is playing until a suspicious part receiver which has not been tampered manual shows should have voltage in- is discovered. Then the only sure test is with, and which brings in the stations dicates an open resistor or coil or a to replace it and play the receiver for on their correct dial markings. Even short -circuit, usually in the form of a several hours. Loose elements in tubes then, there is danger of misaligning blown bypass condenser. An open cir- are often the cause of intermittents; instead of aligning. Editor) cuit reduces the voltage at the point it in fact, every part in the receiver is The mixer and r.f. stage (if any) should feed to zero, with little effect on suspect and great patience may be re- trimmers are similarly adjusted, al- other points. Zero voltage at the plate quired to locate the guilty one. though it is doubtful that one setting of the output tube, for instance, and Do not use a screwdriver or other will give maximum response over the normal voltages at other points, would metal instrument for moving or tap- entire band; so a compromise setting make 'the serviceman suspect the pri- ping parts. There is too much chance must be chosen to give best results over mary of the output transformer. In a.c: for it to slip and cause a short. the most -used part of it. As a general When replacing defective parts try to rule these trimmers should be adjusted duplicate the electrical characteristics near the high-frequency end of the dial. of the original, but, with the exception Earlier we put a "hands off" sign on of tuned -circuit components, a large the oscillator trimmers because they de- variation may have little effect on per- termine the accuracy of the dial cali- formance. Space permitting, voltage bration. However, if the calibration is and wattage ratings may always be in- incorrect it may be corrected if a little creased. The capacity of bypass and care is taken. If the receiver uses spe- filter condensers can usually be made cially shaped oscillator condenser plates larger, often with beneficial results. for tracking, tune in a station near Resistance values are sometimes more 1450 kc and adjust the oscillator trim- critical, but often may be increased as mer until the station comes in at the much as 50% without much effect on correct point on the dial. performance. A study of the circuits. and In receivers using both series and 1 application notes in the tube manual parallel trimmers, the parallel trimmer will quickly acquaint you with the very (mounted on the variablb condenser) is few components whose values are criti- adjusted near 1450 kc and the series cal. trimmer (padder) near 600 kc. The adjustments interact somewhat so they A tube manual and multimeter are chief tools. Larger receivers should be repeated for maximum ac- d.c. receivers all plate and screen volt- From the serviceman's viewpoint, the ages are obtained from a common point, big differences between a.c: d.c. midgets so a short circuit anywhere causes a and more elaborate receivers are more drastic reduction in all B-voltages. tubes and higher voltages. Both mean No instruments are required to de- additional points of possible trouble. tect excessive hum. If an 8-pf capacitor More tubes mean more circuits, and temporarily connected in parallel with higher voltages more dropping and de- one of the filter capacitors reduces hum coupling resistors, with their bypass level, the filter capacitors should be re- condensers. A systematic approach will placed. locate the troubles in these receivers As the tube manual will tell you, the quickly. With the filaments in parallel, best test of a tube's worth is how well one tube's burning out does not affect it works in the piece of equipment con- the others. The bad one is easily de- cerned. Trying a doubtful tube in an- tected because it is cold. Open resistors, other receiver or replacing it with a new which are relatively common, are quick- one will give all the information re- ly located with the ohmmeter (power quired. But there are indirect methods off) , or with the voltmeter (power on) . which may be used to obtain an ap- Personal three -way portables yield to proximate idea of a tube's condition the same treatment as the others. If the receiver works on commercial power, without a tester. Measure the cathode Be sure set is off when measuring resistance. voltage. If it. is lower than the rated but not on the batteries, the batteries value, the cathode emission is probably are probably dead. (Batteries should be curacy. After the oscillator is adjusted low. Too high a reading may mean a replaced when their voltage has dropped readjust the r.f. stage and mixer trim- shorted element or that a leaky coupling one- third, measured under load.) If the mers. condenser is applying positive voltage receiver works on batteries and not on Receivers using permeability tuning to the control grid. commercial power, the trouble is in the are set on frequency by adjusting the Touching a finger to the control grid rectifier circuits. And if it works on oscillator padder near 1450 kc and the of a good audio tube will produce a hum neither, the trouble is one of those pre- position of the slug in the oscillator coil in the speaker. Touching the control viously discussed. near 600 kc. The r.f. and mixer stages grid of the first audio amplifier will are similarly adjusted for maximum immediately reveal whether a signal can Alignment methods output. get through the audio section. Aligning a receiver without a test This method of correcting frequency The oscillator section of the mixer oscillator seems a hopeless task; never- calibration assumes that the i.f. is rea- may be tested by putting the test meter theless it can be done with nothing more sonably close to its original frequency, between its control grid and B- minus, than a neutralizing tool and your ear. and that the calibration was correct with an r.f. choke in series with the If the high- frequency oscillator is not when the set was new, both reasonable meter. If the tube is oscillating, the disturbed the job is especially simple. assumptions. meter will read a few volts negative and To align the i.f. amplifier tune in a The aim of this article is not to be- touching the grid will cause the reading weak signal, and, starting at the sec- little adequate test equipment, but to to decrease. ond detector, adjust each trimmer in show that successful radio service work the i.f. transformers for maximum de- can be done with a minimum of it. Un- Those intermittents flection of the tuning indicator. If the doubtedly, a receiver can be serviced Intermittent troubles take a perverse receiver does not have a tuning indi- more rapidly with additional equipment, pleasure in not appearing while the re- cator, simply adjust the trimmers for which should be acquired by anyone who ceiver is being worked on. To find them, maximum audio output on a weak sig- intends to service receivers tregularly. JANUARY, 1949 Servicing, 54 I I pack up some tools, disgústedly, collect a bunch of repaired chasses, and start out to the truck to make my rounds. It's late when I get back, and I find that Pedro has locked up and gone home. Next afternoon Pedro comes in after school wearing a look of smug satisfac- tion. I can see he's got something on his mind, so I set down my soldering iron, and give him my full attention. "Okay," I say. "Let's have it' "You're wrong," he says gleefully, consulting a piece of paper on which he has apparently taken notes. "The prof says 'Z' is the algebraic sum of the inductive and capacitive reactances tending to resist the flow of current in an a.c. circuit." He grins at me tri- umphantly, and looks at his paper again. "And a device possessing capaci- tive reactance is known either as a condenser or a capacitor, never as an impeder." I open my mouth to give him the business, but just then the door slams, and I see through my peephole that the fat boy with the overcoat is back, complete with reinforcements, so I He slams something down ... with a vicious thud. It's a filter condenser, a cardboard- encased dual job, its pigtails waving. thumb Pedro out front to take care of him. "I wish to see the proprietor," the high voice wheezes. "In person." I figure the portable has popped a tube, and I walk out resignedly. But he hasn't got a radio with him. His The Impeded Double -Cross hands are flat on the counter, and a nasty smile is on his flabby face. Be- hind him, staring at the floor, is a short, thin guy in greasy coveralls. Every radio serviceman will enjoy this piece of fiction, "I'm afraid you're in trouble," Fatty starts off, still leering at me. "Remem- ber the radio you fixed for me ?" He which contains more truth than many a scientific article accents the "fixed" heavily. "Yes," I say. "I do." "Allow me to introduce myself," he says, hands still flat on the counter. By GUY SLAUGHTER "I'm T. William Pearson." He pauses reverently, as though waiting for me to salaam, but the name doesn't mean a thing to me. HE'S a big, flabby geezer in a "Hi, Herk," he says, walking back "So ?" I say. natty overcoat and precisely to the bench. "What's 'Z' mean ?" His red face turns a trifle redder, creased felt hat, and I in- " 'Z' ?" I say absently, squirting car- but he continues. stinctively dislike' him when he bon tet into a noisy volume control. "I own and operate Pearson Motor walks in the door and produces a "What're you -talking about ?" Sales and Service, of which you have claim check. - "Physics," Pedro says, leaning bis no doubt heard." He pauses again. "My radio done yet ?" he whines, his elbows on the bench and staring into I nod, and repeat my question. voice high and wheezy. the chassis I'm working on. "The prof "So ?" I glance at the stub and note the says we got to remember `I equals E By now his moon face is crimson. number. over Z', but he don't say what 'Z' is." "I also happen to be the newly - "Sure is," I say, reaching the little "Impedance," I say shortly. "That's elected president of the MFBEA, and three -way portable off the rack and Ohm's law for a.c., and 'Z' is the im- as such I am opening a newspaper laying it on the counter. "Good as new pedance." campaign against sharp dealers like again." "What's impedance ?" asks Pedro. you." I write him out an itemized ticket, poking a finger into the wiring and "What's the MFBEA?" I break in. he peels the six -buck charge off a thick flipping a blob of dripped solder off a "And whattya mean sharp dealers ?" roll, screws his fat face up into a leer- terminal lug. He pauses dramatically, lifts one ing grin, tucks the radio under his So I grab a scratch pad and explain, hand, and waves it like a ham actor. arm, and starts out the door. in words of one syllable, the difference "Merchant's Fair Business Enforce- "Il1 be seeing you," he says. "Soon." between resistance and impedance. ment Association," he squeaks. His The way he says it it sounds like a Finally I run out of breath and break hand stops waving and moves toward threat, but I just nod, ring up the my pencil point, simultaneously. me. He waggles a fat finger in my money on the register, and go back "Thanks, Herk," Pedro says. He face, his voice rises to a shrill scream. to the bench. points to a resistor in the up -ended "We're pledged to expose you sharp Pretty soon Pedro, the little Mexi- chassis. "That's a resistor, ". he indi- dealers who prey upon the public and can kid who works for me, comes in, cates a condenser, "and that's an im- suck the blood of unfair profits from school being over for the afternoon. peder, huh ?" the economic veins of our fair city...." RADIO- ELECTRONICS for 33 Get Your ALLIED Catalog Now 180 Value- Packed Pages Featuring Everything New in Radio! NEW Projection Television by Hallicrafters -16 "x12" Screen Amazing 192 Sq. Inch Picture! Develops a brilliant, steady, optically correct picture; glare -free for comfortable viewing both at close range or distance, day or night. Optical system stays in per- Send for the ONE COMPLETE fect, stable adjustment. 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Jackson Blvd., Chicago 7, Illinois I Send FREE 180 -Page ALLIED Catalog t O Enter order for Hallicrafters Model t Enclosed Fu P $.. D Part Payment (Bal. C.O.D. ) SrfPrltd41 Send ALLIED Easy Payment Plan details and order blank. uc Retetca Name aacd Eßectrw.cit.a Address I I City Zone State s JANUARY, I949 I tcricis 56 "Wait a minute, Buster," I inter- mally." He licks his lips, casts a side- key dutifully at his heels. I stand there rupt him, my plate current rising to long glance at T. William, and drops for a minute and watch them climb saturation. "You come in here calling his eyes back to the floor. into a shiny black sedan out front; people names and making false accusa- "Okay," I holler. "That wire must've then I head for the bench and sit down tions and you're going to lose a couple been the hot lead to the i.f. trans- dazedly to think it over. of those chins!" former. The winding showed no con- In a few minutes the door opens, He draws back a step, some of the tinuity, so I replaced the whole trans- and Pedro strolls back and greets me color seeping out of his face, and throws former." Fatty is leering at me, all of with a big smile. a glance at his companion. his chins bobbing, and Pedro is squint- "Wanta see the fun ?" he asks hope- "False accusations, huh ?" he bleats. ing from one to the other of us, trying fully. "We'll see about that." He turns to to decide which one to vote for. "Any But I just wave my hand at him, the little guy, and waves a hand at radioman would have done the same and dig deeper into my gaze, so he him. "This is my chief mechanic, and thing," I argue. "It's a perfectly rou- wanders out front and leaves me alone. he knows about radios, too." tine procedure." After a while I rouse myself and The little guy looks up, catches my T. William raises one hand to his go to the telephone. The lawyer on eye, and drops his head again, his pasty mouth, blows idly at his fingertips, the other end of the line listens to my face turning a pale pink. Out of the yawns, and leers at me again. story in silence, and asks me whether corner of my eye I see Pedro looking "I dare say," he says. "All that for T. William's radio did have just a cut from one to the other of us, obviously one cut wire. It will make interesting wire wrong with it. I tell him yes, I as mystified as I am. T. William con- reading in the paper, I'm sure." guess so, he clucks his tongue dis- tinues his tirade. "Look," I blurt, trying to keep my provingly, and hangs up. "Jonas here cut a wire in my radio, voice calm. "Mr. Pearson, you're mak- "Should have seen it, Herk," Pedro one little wire mind you, and I brought ing a mistake! A gimmicked radio is says, coming away from the show win- it here to test your honesty. You no test of a radioman's honesty or dow where he's been peering into the charged me six dollars to fix it. Ob- ability. In the routine of radio repair street. "He was so mad I thought he viously you are a cheat and a fraud, you just don't look for rigged -up de- was going to kick the poor little me- and I intend to see to it that you are fects." chanic." He chuckles appreciatively. run out of business. The MFBEA shall Pedro has apparently made up his "They finally towed it away." state the facts in the paper for all mind, and he slips quietly out the front "They did ?" I say absently. "What ?" to see, in a half -page paid advertise- door. I feel like a ship being deserted "T. William Pearson's car," Pedro ment." He pauses for emphasis, breath- by her crew when it is needed most. says, eyeing me a bit apprehensively. ing heavily, one hand aloft. "A cut wire," the flabby one wheezes, "It wouldn't start." I stand there with my mouth open, "should be a cinch. Either you are in- "Good," I say, wondering how many wondering what a lawyer can do for competent to be trusted with people's people will see that half -page ad. "I me. The words "libel" and defamation radios, or you are downright dishonest." hope somebody stole the engine." of character" flash through the space He smiles his nasty smile again. "Either "Nope," says Pedro thoughtfully. between my ears, followed by "attor- way, you shouldn't be in business and "Too much impedance." ney fees" and "supreme court." After the MFBEA will see to it that this "Yeah," I echo, wondering where I a minute I come to. The fat guy is still fair community's citizens are made can find a nice town full of defective posing like the avenging angel, the aware of that fact." He tips his natty radios to open a shop in. "Too much pasty -faced mechanic is still looking hat at me disdainfully, and heads for impedance." floorward, and Pedro is regarding me, the door, the pasty-faced grease -mon- Pedro looks kind of disappointed, at wide -eyed, somewhat as he would a cat whose disguise has just slipped, revealing instead a skunk. I grab the card -index off the desk, and thumb through it until I find the job ticket labelled "Pearson, T. W." I lay the card on the counter, and read it to myself, and then aloud. "Olympiad three -way portable," I read, my voice sounding strange. "Open second i.f. transformer replaced, set tracked and aligned. Total, six dol- lars." I look up, feeling kind of empty inside. "Look, Buster," I manage weakly. "That's a perfectly legitimate charge. The i.f. transformer was open, so I installed a new one, realigned the set, and you paid for time and mate- rials used on the job." T. William clears his throat tri- umphantly. "There was just a cut wire," he wheezes. "That's all." I turn to the mechanic, who is still looking at the floor. "A cut wire ?" I manage to ask him. The little guy takes a deep breath, raises his eyes until they are fixed determinedly on my necktie, and reels it off as though it is memorized. "I removed the chassis from the cabinet, peeled the insulation off a red wire, cut the wire, and replaced the insulation to cover the place where the wire was cut. Before I performed this operation the radio played nor- RADIO -ELECTRONICS for 57 fl 1948 TELEVISION manual INCLUDES EVERY POPULAR TELEVISION RECEIVER In this giant volume of television factory data, you have everything you need to repair every modern television set. For only $3, total price, you get complete service and alignment material on all popular T -V sets. You receive easy -to- understand explanations of circuits, 144 pages of alignment procedure, test patterns, T -V antenna data, response curves, oscilloscope waveforms, voltage charts, adjustment hints, many Compiled by M. N. Reitman, diagrams on mammoth 11x17 -inch blueprints, everything to bring you radio engineer. up to date and make you an expert in television repairs. teacher. author & serviceman. FIND -FIX ALL TELEVISION FAULTS BIGGEST BARGAIN T -V TRAINING Use this new practical "cyclopedia" of For 15 years, radio servicemen ex- television servicing as your guide to quick pected and received remarkable values fault finding and repair of any modern in Supreme Publications service manuals. television set. Eliminates guesswork -tells The new 1948 Television Manual is a you just where to look and what to do. virtual treatise on practical television Cuts hour -wasting jobs to pleasant mo- repairs. By normal standards, such a ments. Use test patterns for quick adjust- large manual packed as it is with practi- ment, or look up probable cause of trouble cal data, illustrations, diagrams, charts, in the pages of hints after simply observ- photographs, and expensive extra -large ing fault of picture on screen. No equip- blueprints, should sell for $10 -but as ment needed with these tests. Or use your another Supreme special value, it is 1948 TELEVISION volt -meter and compare values with many priced to servicemen at only $3, post- Contains material on all popular television sets, voltage charts included. Observe wave- paid. Only a publisher who sold over one of Admiral. Belmont Radio, DuMont. Farnsworth, forms similar to hundreds illustrated using million various General -Electric, liallicraften. Motorola. Milo. of radio manuals can 1t.C.A., Sonora, Stromberg- Carlson, and others. test points suggested and in a flash locate offer such bargain prices based on tre- Gives description of circuits, inane pages of tent what used -to -be a hard -to -find fault. mendous patterns, response curves. oscilloscope waveforms. This volume- sales. Read about this alignment tables. service hints- many diagrams in manual will give you the know -how of a new T -V manual at left. Find out about the form of giant double- spread blue- prints, test points, voltage charts, etc. television expert and will repay for itself other radio manuals listed below. Use Largo sloe: 85íz11 in., manual style with time saved on the first T -V job. Order and save with Supreme Publications. binding, flexible covers, priced at only. at our risk for a 10-day trial. RADIO DIAGRAMS AND F.M. SERVICE MANUALS You can speed -up and simplify radio repairs with Su- preme Publications Manuals. Service radios faster, better, easier, save time and money, use these most -often- needed 1947 diagram manuals to get ahead, earn more per hour. For the remarkable bargain price (only $2 for most volumes) rlosi - Offen -Neel you are assured of having in your shop and on the job, needed diagrams and other essential repair data on 4 out of 5 sets you will ever service. Every popular radio of all r'.m makes from old- timers to new 1948 sets, including F.M. and Television, is covered. Clearly printed circuits, parts Televisiol lists, alignment data, and helpful service hints are the and "tor facts you need to improve your servicing ability. Let these Sam manuals furnish you with diagrams for 80% of all sets. There is no need to spend large sums for bulky, space - wasting manuals, or to buy additional drawings every few 1.;;;;; weeks; be wise, use SUPREME Manuals to get the most in diagrams Television 1948 Radio Diagrams and service data for the smallest cost. Select F.M and manuals at left and below. Check titles you want to Use this extra -large manual of fac- Be prepared to repair quickly all examine and rush "no- risk" coupon today. tory instru tions for trouble-shoot- new 1948 radio receivers. In this big ing, repairing, and alignment of all single volume you have clearly - popular 19 7 F.M. and Television printed, large schematics, needed sets. Covers every popular make, in- alignment data, replacement parts cluding F.M. tuners, AM -FM com- lists, voltage values, and information on stage gain, location of trimmers, binations, and all types of television and dial stringing, for almost all re- receivers. Detail circuit diagrams, cently released sets. Makes toughest theory of operation, test hints, align- jobs amazingly easy. Find all faults ment data, including both meter and in a jiffy. A worthy companion to the oscilloscope methods. Use this recent 7 previous volumes used by over 120; Supreme manual to save time and 000 shrewd radio servicemen. Will money on your very next F.M. job. pay for itself on first job. Manual 1947 1946 1942 1941 1340 1939 1926 -1938 Data presented on 192 large pages. covers models of 42 different manu- -OFTEN 81/2x11 inches. Sturdy, manual -style facturers. Giant size 8'/2x11 inches. MOST -NEEDED RADIO DIAGRAMS DIAGRAMS binding. Tremendous value ! 192 pages ex. Manual- Each manual has between 192 and 208 pages of diagrams, Price postpaid, only + a style bindi Price only.... alignment data, voltage values, and service hints, 240 Pages manual style, large size, 83's11 ". Price, each 2 Price $2.50 Record Changers Radio Servicing Course -Book Here is your practical radio course of 22 NO RISK TRIAL ORDER COUPON Posf -War Manual easy -to- follow lessons. Review fundament- als, learn new servicing SUPREME PUBLICATIONS, Service expertly all modern tricks, all about signal I 3127 W. 13th St, Chicago 23, ILL. (1945 -1948) record changers. tracing, oscilloscopes, re- Ship the following manuals on trial un- Most -Often -Needed Includes every popular make. cording, P.A., test equip- Ider your guarantee of satisfaction or Just follow simplified factory ment, and T -V. Just like money -back. Radio Diagram Manuals I instructions to make needed a $100.00 correspondence adjustments and repairs. Hun- course. in New 1948 Television Manual. ...$1.00 PRICED dreds of photographs and ex- Everything I 17 ' radio servicing. With self - /1 ploded views. Large size: 1947 F.M. and Television 2.00 AT ONLY testing questions and in- Manual p 1946 1 I 8 %x11 inches. 144 fact -filled dex. Large size: 81/2"x11 ". I Post -War Record Changers 1.50 CI 1942 \ pages. Price postpaid, 4! `11 Great value, S2s only $ 1 $$ $250 194 New 1948 Edition only O Radio Servicing Course-Book.. 2.50 1 L I 1940 EACH ICl I am enclosing $...., send postpaid. 1939 Send C.O.D. I am enclosing 8...deposit. 1926 -1938 - $2.50 supreme Publications I Name: sou by all Leading Radio Jobbers IAddress: JANUARY, 1949 581 Servicing CONDENSERS -PAPER TUBULAR 600 WV -.001, 002, .005-8e: .01. 05-9e; 1 -I0e; 25 -23e; O5- that, but I'm too busy thinking black through it still wouldn't run. They 35e; ELECTROLYTICS: 8mfd 200v -20e; 100mfd 35v minutes and -20e; 30mfd 150v -23c; 20 /20mfd 150v -35c; 30/20 thoughts to pay much attention. And just found it a few ago, 150v -46e: 50mfd 150v -43e: Bmfd 475v -34e: 16mfd after a little, from sheer force of habit, I've been paying them time- and -a -half 350v -65e; OIL CONDENSERS: 4mfd 600v -69e, 2mid 600v -49e; 3X.lmfd 600,-29e. I collect some tools and start off in the since five o'clock last night." He pauses, SP EA K E RS -These PM speakers are the finest that arc truck to make my rounds. breathless, then waves his fist at me. available. All hava heavy oversize Alnico V magnets. I struggle through my bench work "I'm suing you for the entire cost 31/2r $1.15 6 for $6.60 4' 51.15 . 6 for $6.60 the next day, wiring filters up back- plus damages," he whines. Then he 5' $1.10 10 for $9.50 6' $1.50 6 for $8.70 wards and in general doing everything heaves the door open, stands in the 6'x4 Oval $2.10 6 for $10.80 7' (Car Radio size)... $4.50 6 for $21.50 wrong, so I'm still hours behind sched- doorway for a minute, and stalks out, 8' 10 oz. ... $3.95 6 for $20.50 ule when, middle muttering to himself in a high screech. r 21 oz. . $4.95 6 for $26.50 about the of the 10° 21 oz. ... $5.50 6 for $30.00 afternoon, Fatty shows up again. He's I watch him climb into the sedan at 1r 21 ox. ... $7.95 6 for $42.00 alone this time, and I can tell he's hop- the curb, and pull away, his lips still AUTO -TRANSFORMER-Steps up 110v, or steps down 220v to 110r- $2.95. ping mad even before I leave the bench moving, and scratch my head in sheer FIL. TRANSF.: 6.3v, 3 Amps.- $f.35; Universal Output Trans. 6 Watt -89e: 18 Watt-$1.29; 30 and get out front to face him. bewilderment. Then a blinding light Watt- $1.69. AUDIO TRANSFORMER: S ('late to in my alleged S. Grid. 3:1 -79e; S. l'lato to P.I'. Grids -79e; His pudgy hands are clenching and flashes brain. Heavy Duty Class AB or B. P.P. inputs -$1.49: unclenching, his face is gassy- rectifier "Pedro," I say, my voice rising ten Midget Output for AC -DC sets-69e; MIKE TRANS- FORMER for T -17 Shure microphone. similar to purple, and all the time gaspy, popping decibels with each syllable. "Pedro, UTC ouncer type -$2.00. Staneor SB or DB mike to line or grid -$1.95. sounds are being beamed from him to you come out here!" POWER TRANSFORMERS -Half -shell type. 110V. 60 ey. Centertapped HV winding. Specify either 2.5 me. The little guy strolls out, his face or 6.3V filament when ordering. I stand there a minute just watch- a mask of innocence, closely scrutiniz- For 9 -5 tube sets-650V, 90MA, 5V & 2.5 or 6.3V $1.49 ing him burn, and then I find my voice. ing his fingernails. For 5-6 tube seta -650V, 453tA, 5V & 2.5 or 6.3V 1.75 "Now what ?" I say wearily. "Pedro," I say, forcing myself to For 6 -7 tube sets -875V, 50MA. 5V & 2.5 or down on the tone down a little. "What was that 6.3V 1.90 He slams something For 7 -8 tube sets-700V, 70MA, 5V & 6.3 or counter with a vicious thud, and I see all about ?" two 25V 2.35 For 7 -8 tube sets -700V, 7051A, 5V & 6.3 (25 it's a filter condenser, a cardboard - He smiles half -heartedly. Cycle) 3 60 For 8 -9 tube sets -700V, 90MA, 5V -3A, 2.5V- encased dual job, its pigtails waving. "What d'ya mean, Herk ?" 3.5A, 2.5 -10.5A 2.85 "That ?" he gurgles, I For 9 -11 tube seta -700V, 5V & 6.3V -9A 2.95 yours exuding "You know what mean," I say, For 9 -15 tube sets -600V, 150MA. 5V & 6.t3V 2.95 a purple mist. trying to keep my voice calm. "I mean "Could be. I use that brand. Why ?" my in direc- 1000 CYCLE AUDIO FILTERS him!" I jerk thumb the Navy PD52010-1 low pass audio filters as mentioned in "I'll sue," T. William screeches, tion of the front door. the "Peaked Audio' article In June CO. and designated by the above number. are the exact electrical and waving his arms about. "I'll sue you "Oh," says Pedro blandly. "That." physical equivalent of commercial audio filter units selling for $35.00 wholesale. They are infinitely better for everything you've got. You can't I tap my foot menacingly, and eye than the surplus 'Radio Range Filters" being sold for reducing QRM. and at 2 KC off resonance for example. get away with this." him coldly. a 2 section filter using PD52010 -1 Is capable of twice "Huh ?" I say, staring at him. "I just rammed that thing into the the selectivity available ihm the use of the 05 -er (the BC453 section of the 279N which hoe provided the His squeaky voice oozes up toward exhaust pipe, is all," he says inno- amateur's prevloue highest standard of interference elimination). EXTRA SPECIAL ,-NAVY PD52010 -1 the high -frequency limit of my hear- cently, pointing at the filter on the with diagram $5.00 ing, and I think he's going to blow a counter. "And then I guess his car One hundred resistors $1.95 fuse. wouldn't His eyes are very big Ten metal & Bakelite Knob,..(no wooden knobs) 39e start." Six variable condensers, including butterfly types $1.49 "It's sabotage," he wails. "I'll sue and cocker -spanielish. "Too much im- Ten ILF. Chokes. including high frequency types 35c Four volume controls without switches 95e for every cent you've got." pedance, huh ?" Seven I.F. Transformers $1.98 Five oscillator coils 69e Just then Pedro walks in, takes in I stare at him for a full minute, and The above 7 assortments listed. ein be purchased to- the situation at a glance, stares for a he to squirm. gether as one lot at a super -special total price of only starts $6.95. All merchandise guaranteed to be as advertised. minute at the filter condenser on the "Looks like a good mechanic could TUBES -ALL types in stock-Maximum discounts counter, and makes for the back room. find it in no time, Herk," he says, and when ordered in lots of ten or snore. WORLD RENOWNED -700 -page, tenth edition of the T. William spots him as he goes by, he drops one eyelid in a slow wink. 1t.SJ)IO HANDBOOK In cloth binding and hard cover at the sensational reoucen price, Tor a limited Lima and points a shaking finger at his re- Finally, at long last, I wake up. It only $1.49 Book on DRY DISC RECTIFIERS by H. B. Conant, treating back. takes me two minutes to dial the right nationally recognized authority on the subject. "He's your agent, the little mon- number, and another two minutes to get Theory and practical applications 5 .25 ster," he wheezes. "You put him up T. William Pearson on the line. TAKES ALL THREE to it. Contributing to the delinquency "Hullo, Fatty ?" I say. There is a 51095 BIG B ARGAINS call it. You'll never I. SENSATIONAL FASCINATING, MYSTERIOUS of a minor, they'll gasp in the receiver, and I continue. SELSYNS. Brand new delayne made by G. E. Com- get out of jail." By now he's spitting pany. Two or more connected together work perfectly "This is the radio shop, Fatty. What on 110V AC. Any rotation of all over me as he mouths the words. page is the MFBEA running that ad the shaft of one Selayn and all others connected to It will ro- "What the devil are you shouting on ?" I don't wait for an answer, but tate exactly as many degrees in the same direction, following about ?" I manage, grabbing his fat - plunge ahead. "You see, Fatty, I want unerringly as If the units were connected together by stuffed as waggles in front of half of page to shafting instead of wire. rrhis is true whether you twist hand it the other that tell the the shaft of the master unit a fraction of a revolution my face. "Shut off that howling and public that all the mechanics at Pear- or many revolutions. Useful for indicating direction of weather vanes, rotating directional antennas, or con- tell me what goes on." son Motor Sales and Service spent a trolling innumerable operations from a distance. Com- plete with diagram and instruction. Per Matched Fatty stands there breathing hard good many man -hours on a dead engine pair $4.95. for a minute, not quite sure whether that just had its exhaust plugged." 2. ALUMINUM GEAR BOX 18x8x7 that contains two powerful electric motors and two matched gear trains. he's in bodily peril or not, and I take I pull the receiver away from my 02 gears in all varying in sloe from ya to 9 Inches in diameter. This unit is readily converted to rotate a advantage of the fact. head and wait until the splutters sub- beam antenna or any other similar use $5.00 "Speak up," I urge him, "while you're side a little. Then I listen. 3. HOME WORKSHOP AT BARGAIN PRICE. Ac- curate and precise 2 speed guaranteed hobby lathe, the still in one piece." "Oh well," I say. "Same thing, you essential machine for the home workshop. Sturdy enough for light production stork or factory standby service. He backs up a step, looks wildly know. Cut wire or plugged exhaust; a Supplied with 56' of belting for connecting to any about for a means of escape, and sees rigged -up defect is a good test of available electric motor or power take -off. Also included in this unbelievable offer are such accessories as a ;' the door behind him. He retreats toward honesty and ability I've been told." I drill chuck with specially hardened tool steel jaws. a 9' electric furnace high speed grinding wheel, a cotton it, reaches it, and stops with his hand feel my smile spreading over my ugly burning wheel with a large supply of buffing compound. and a 4' steel wire stretch brush. Your cost $6.00. on the knob. That gives him courage. face as I hang up. I'm still smiling Sole export agent. Distributor inquiries invited. "You had that little beast sabotage when Pedro plucks my sleeve. my car yesterday," he says, a little "Is it okay, Herk ?" he asks. BUFFALO RADIO SUPPLY calmer now, beginning to get hold of I dig deep and hand him a buck. 219 -221 G Street, Dept, RE himself. "-My mechanics worked all "Yeah, Pedro," I say. "It's okay." Buffalo 3. New York night and most of today on my engine, My eye lights on the filter. Please send 1949 Bargain Catalog and you're going to pay for it They "And Pedro. You can tell your prof pulled the head, checked the valves, he's wrong." I pick up the filter and Name the head gasket, the ignition, carbure- hand it to him. "Sometimes a con- Address tion, everything, and when they got denser IS an impeder," I say, happily. City Zone.. . State J RADIO -ELECTRONICS for 59 RADIOMEN'S HEADQUARTERS WORLD WIDE MAIL f ORDER SERVICE ! ! GENERAL ELECTRIC 150 WATT TRANSMITTER Cost the Government $1800.00 Cost to You -BRAND NEW -$100.00 This is the famous transmitter used in U.S. Army bombers and ground stations. during the tear. Its design and construction have been proved in service, under all kinds of conditions, ail over the world. The entire frequency range is covered by means of plug - tuning units which are included- Earls tuning has its own oscillator and power amplifier coils and condensen. and antenna tuning circuits-dl designed to operate ut top efficiency within Its particular frequency range. Transmitter and accessories are finished In black crackle- and the milllammeter. voltmeter, and RF ammeter are mounted on the front panel. Here are the specifications: FREQUENCY RANt;E: 200 to 500 KC and 1300 to 12.300 KC. (Will operate on 10 and 20 meter band with slightmodlfication for which diagrams are furnished.) OSCILLATOR: Self -excited. thermo comopensat.ed, and band calibrated, POWER AMPLIFIER: Neutralized class "C" stage, using 211 tube and equipped with antenna coupling circuit which matches practically any length antenna. MODULATOR: Class 'B" -uses two III tubes. POWER SUPPLY: Supplied complete with dynamotor which furnishes 1000V at 350 MA. from either 12 or 24 volts. Complete In- struction are furnished to operate set from 1105' Ac. SIZE: 21%12339[4'. Total shipping wgt. 300 lbs., complete with all tubes, dynamotor power supply, seven tuning units, antenna tuning unit and essential plugs. HEAT GUN Streamlined pistol grip heat gun in vivid red housing, that delivers a powerful 10 Cubic Ft. per minute blast of hot Sensational Value in air at 160 Fahrenheit. Ordinary blowers have small fan motors, but this has a lifetime -lubricated AC -DC motor of the rugged vacuum cleaner type, that produces a hurricane AC -DC Pocket Tester of either hot or cold air. Perfect for blowing out dirt or dust from radio chassis, drying out ignition systems, warm- This analyzer, featuring a sensitive ing up carburetors. quick-drying paint. thawing out radia- repulsion type meter housed in a tors or water pipes. etc. Wammg: -Keep this away from bakelite case. represents the culmina- your wife, or site will be using it to dry her hair because tion of 15 years achievement in the it will do it in half the time of the ordinary hair dryer. instrument field by a large company to say nothing of her using it to dry stockings or clothing, or specializing in electronic test equip- defrost the refrigerator instantly. Only $12.95. Satisfaction ment. guaranteed or money refunded if returned prepaid within 5 days, Specifications of the AC-DC Model Volt- Ohm - M Ill l ammeter: GENERAL ELECTRIC RT -1248 15 -TUBE TRANSMITTER- RECEIVER AC Volts -0.25, 50, 125, 250 TERRIFIC POWER -(20 watts) any two instantly lected, easily predlusteda frequencies from 435 to DC Volts -0.24. 50, l''AS, 250 500 Mc. Transmitter u r tubes including westernElectric 316 A as final. Receiver uses lO tubes In- Milliamperes AC -0 to 50 cluding 955'.. first detector and oscillator. and 3 -7H7's s Ir'x with lug -tuned 00 Mc. IF trans - DC onnen a 7H7µ 7E6's and 7F7's. In addition Unit contains R relay designed to operate any sort of Milliamperes -0 to 50 equipment when actuated Originally Ohms Full Scale -100.000 for 12 volt operation, supply is °notincluded,, as itis a Cinch for any experimenter connect"tñs Ohms Center Scale -2400 unit for 110 AC, using any supply able of 400 DC at 135 MA. The ideal unit for a in mobile or stationary service in the Citizen's Radio Telephone Hand where license is necessary. Instructions Capacity -.05 to 15 S[fd. diagrams supplied for pannin the RT -1248 transmitter either code or voice In AM FM transmission or reception, for use a mobilercpublic address system, on 80 to 11Ó Me, as an FM éroadenst elver. Total price. prepaid anywhere b the U.S. -$7.00 as Facsimile transmitter or receiver, as Amateur Television transmitter receiver for remote Similar DC Meter, lacking the AC operated ranges of above, $5.50 trol °relay hookups, for Geiger- Mueller counter pplieations. It sells for only $29.95 two for $53.90. prepaid. If desired for marine or mobile the dynamotor which ill work n either 12 or 24V DC and supply all power for the set is only $15.00 additional. RT- 1655-11 tube crystal controlled superheterodyne receiver that cover the FM band. The ultra modern circuit uses the latest types COMPRESSED AIR INSTANTLY, Anywhere!! of tubes including 7 miniature 6AJ5's. Beautiful chassis and alu- minum cabinet. Tubes and schematic supplied -- $14.95 Portable Air Compressor and storage tank. Ruggedly built of best materials Using lifetime lubricated ball -bearing on connecting risi and u {I Impregnated main bearing on haftUnusual design forever eliminates valve trouble, the most common fault World renowned 700 page tenth edition of the Radio Handbook in In it compressors. PATENTED unique air intake system increases efficiency tre- cloth binding and hard cover at the sensational reduced price. for a menn°dotia y over other compressors o that air output Is much greater than that erinute deliver approximately limited timo only. $1.49 3500 flu. Inches saiir per at maintained pressure 30 RT1711 Brand New 12 Tube, 110 Volt Receiver- Indicator- Oscillo- f complete scope complete with all tubes and. power supply. Has telescoping inflate 90 lb. truck tire In less than me minute. Comes with 100 lb. gauge. although anger-tip adjustment allows setting of outputp pressure at any hood over scope tube. which is equipped with a detachable calibrated which ill automatically he maintained. works from y r/ N.P. motor. screen. Iles centering and amplitude. controls two video Uvalue.seful for spraying paints or lacquers. disinfectants. insedlrOles, annealing or and inputs. brazing inflating $14.50 A natural for television $39.95 the U.S. Emeient "cn adjustable syphon spray gunrecoompletewwith 12 ft. of 100 lb. tested hose available for only $7.75 with pint container, also Latest type PM Speaker in a fully -enclosed black crackle finished prepaid. 25% required on all C.Ó.D. orders. metal cabinet. This speaker and case match comsutlniration receivers. and In addition make perfect intercom remote stations. Our price. Including output transformer TERRIFIC VALUE - $4.50. $4.95 ELECTRIC DRILL Stupendous Value in 3 Section PERMEABILITY TUNER PORTABLE The heart of one of this year's hottest radios. The entire tuning radio. equipped with .Jacobs Geared Chuck and Key. sections lita wireel wound.d. ll 3 tunedycircluits adjustable at both Only $20.95 ti" low d high ends of dial. Amazingly tiinyyg (Ax3x2t,y). Compact Not an Intermittent duty drill, but a full size rugged tool. enough be Will substitute for entirBeey origin tuning ssyystecm o including Most convenient type snitch, natural grip handle, and balance like a six -shooter. variable ndenser or if desired the originall tuning condenser can be cut turbine type cooling blower long brushes. instrconnected to these as, and the a to proper inductance (no Precision gears- -extra uments required). and the set tuned Just heron., lthoueh No stalling under heaviest pressure because of powerful 110 Volt AC -DC motor and sensitivity will multiple section will cut Undesirablel ablebinterf interference multiple ball thrust bearing. n knife. or if only little bit better than average results with awithslugtuncd w etrattppoO necessary, the unit n be split up in a Other bearings self -aligning lifetime- lubricating Chrysler oilite type. minutes 3 be used Made for toughest year -in and year -out service In Plant or on construction Jobs. These coils. xsupecompa and Steally hot, sso indiv duallynreplace an. broadcast hand RF, oscillator, or 1st detector coil with Im- Amazing perpetual factor' guarantee assures you of a lifetime of trouble -free use. rnt in resulta in any set. After seeing onen of these units. yvou'll pier a dozen just for eneral repair placement work. 25% deposit on C.O.D.'a. Full refund if returned prepaid within five days. Cost the manufacturer several dollars. Your cost $1.49. SELENIUM RECTIFIERS Our PE -109 32 -Volt Direct Current Power Plant (May be used at any voltage lower than rating) This power plant consists of a gasoline engine that Is direct coupled to a 2000 - I.2 ampere 30 volt S .90 watt 32 volt DC generator. Whitt unit is ideal for use in locations that are not (above Can be parallelled for battery charging) serviced by commercial power or to run many of the surplus items that require 25 MA 50 Volt 9 .49 24.32 Volt DC for operation. The price of this power plant tested and In good ., MA 120 VOIt .70 condition is $79.95 F.O.B. Buffalo, or we can supply in strictly "as IC' con- ion MA '20 Volt .75 dition for F.O.B. New York City. These latter are exactly as received, in 150 MA 120 Volt .80 $58.95 200 MA I "O Volt 1.0$ heavy steel- strapped gov't cases, and ne are unable to determine If the In- 250 MA 120 Volt 1.25 dividual units are new or used or what the condition is if used. while the $79.95 MITER RECTIFIER -Full w may be used for replacement. or in units are some of the same that have been brought to Buffalo for testing and construction of all types of test equipment- S1.2S. Half Wave -90c. repair If necessay. We do not recommend gambling on the "as is" condition except for quantity purchasers. We can also supply a converter that will supply 110V AC from the above unit or from any 32V DC source for 312.95. CERAMIC INSULATED VARIABLE AIR CONDENSERS 350 mmfd. smoane- 91.93; 4 gang- $1.49; 3 yang -$l.29 10 l S.35 -10 for 52.90 -100 for $23.00 SCR -274N COMMAND SET as mmf 5.35 -10 for $2.90 -100 for $23.00 25 mmf S.35 -10 for 53.90 -100 for $23.00 The greatest radio equipment value in 35 mmf 1.40 -10 for 53.40 -100 for $29.00 SO mmt $.45 -10 for $3.70 -100 for $30.00 history 75 mmf 5.50 -IO for 54.40 -100 for $38.00 3 loo mmf 5.55 -10 for $4.93_100 for $39.00 A mountain of valuable equipment that includes 140 mur .50-10 for $7.40 -100 for $64.00 receivers covering 190 to 550 KC; 3 to 6 MC; and 6 ranime s1.0o -10 for 59.90 -100 for $70.00 to 9.1 MC. These receivers use plug -in coils, and 2 Gang 140 mmf $1.60 -10 for 512.50 -100 for $100.00 consequently can be changed to any frequencies de- Butterfly condensers, rotor has two ball bearings and n n shaft. 1E mmf. per serties, 5.50 -10 for $4.50 -100 for 540.00 sired without conversion. Also included are two Tun- 30 section 5.80-10 for ing Control Boxes; 1 Antenna Coupling Box ; four mmf. per -O for sá.3Ó-100 9e0.Ó 28 V. Dynamotons (easily converted to 110 V. opera- Manufacturers and distributors write for prices on larger quantities. tion); two 40 -Watt Transmitters including crystals, WE HAVE OVER 250,000 VARIABLE CONDENSERS IN STOCK. and Preamplifier and Modulator. 29 tubes supplied in all. Only a limited quantity available, so get your MICROPHONES-Super Special -Highest quality alt chrome bullet order in fast. Removed from unused aircraft and in shaped CRYSTAL MIKE of taillight nationally known brand-S5.95. Bullet DYNAMIC MIRE -57.95. MIRE Jr. -SOC, IRE with guaranteed electrical condition. A super value at switch on handle -90c, IKES- (Specify whether carbon or $34.95, including crank type tuning knobs for re- magnetic) -93c. ceivers. Without these knobs the receivers can't be tuned, and are only useful for parts. Don't buy Scoop -Brand new AEROVO% COND[N$[RS-40. 20. 20 Mfd. at 150, without knobs! 130, and 25 W.V. Fully guaranteed. Ten for $4.40. BUFFALO RADIO SUPPLY, 219 -221 Genesee St., Dept.RE- BUFFALO 3, N. Y JANUARY, 1949 sol New Devices high -fidelity audio transformers in- TUBE AUTO ANTENNA clude a complete range of units for SOCKETS RADIO -INTERCOM LEAD -IN amplifiers, speakers, microphones, and Yates Engineering Services, Satchel! Carlson, Inc., Federal Telephone and Radio pickups. Cranford, N. J. Saint Paul, Minn. Special coil and core construction A combination tube Corp., East Newark, N.J. socket and The Radio Dor -A -fone, Model 458RD, results in the reduction of hum pickup mounting strip is made of steatite or rs a combination radio difficulty with automo- receiver and A principal and leakage reactance as well as of plastic. The socket is supplied mounted 2- station intercom. The receiver con- leod -in wire has been the bile antenna harmonic and intermodulation distor- to the terminal board. tains four tubes and a selenium recti- high capacitance. due to the shielding. tion. Resistors and capacitors associated fier, e loop antenna, and a 5 -inch The HF series, except for the HF -65 with the stage can be soldered to the speaker. Quick- heating tubes are used output transformer, has a frequency socket and strip before the unit is in the device. response of ,1 db from 20- 20,000 cycles. mounted in the chassis. Four push -buttons atop the master The HF -6S has a response of ±1 db Breakdown of mass production into unit serve as switching controls. The from 30- 20,000 cycles. The WF series, simple subassembly operations is made first turns the set off, the second feeds except for the WF -21, has a frequency possible, and -especially in military radio programs to the master speaker. equipment characteristic of $2 db from 30 -20 -.000 - rapid servicing can be the third feeds programs to both mas- done merely by removing cycles. The WF -21 input transformer bas the entire ter and substation, and the fourth is stage and replacing with a new a response of ±2 db from 50. 10,000 it one. used as e conventional talk- listen in- tercom cycles. switch. The master is 7 inches wde, 7 inches SMALL STORAGE deep, and 6i /2 inches high. The sub- DRAWERS station measures 5% x 4% x 5 inches. A special weatherproofed substation is The new K -109 cable reduces capaci- Cincinnati Ventilating Co., Inc. available for outdoor use when that is tance to 8 utf per foot by surrounding Covington, Ky. desired. the center conductor with air. This con- Every ham. serviceman, experi- ductor is supported in a tube of poly- menter, and constructor early in his VIDEO BRIGHTNESS ethylene by being crimped into a career runs into the problem of storing sow -tooth form and pressing the points resistors, capacitors, screws and nuts. TESTER of the sow -tooth against the inside of and o thousand other small parts. The Photovolt Corporation, the tubing. The shield and outside in- new interlocking smoll ports drawers sulation surround the polyethylene are made of steel. Each drawer and its New York, N.Y. tube. housing is 21/4 x 2% x 5 inches. The Model 205 video brightness tester measures housings ore tongued and slotted so the brightness of cathode - that they con be put together to form ray viewing tubes. It is designed for RADIO TIMER a rigid and durable cabinet of laboratory tests, production control, International Register Co., drawers of any size or shape. Starting installation, and servicing. A photocell with lust a few, the buyer con obtain held against the face of the tube is Chicago, Ill. connected to a meter by o short cable. The RC -1021 timer is on electric clock - The meter is calibrated in foot -lam- which operates a switch. One opera- berts up to 100, covering the highest tion at a setting is possible: if the radio brightens values found. The photocell is on, the clock will turn it offi; hos a filter so that brightness values and if is it off, the clock will turn it on. Both series ore potted in gray are furnished in terms of visual per- enamelled cost cases with four tapped ception. holes on both top and bottom for flush mounting. Stud -type terminals ore pro- vided on a phenolic panel. TV ANTENNA Tricraft Products Co., Chicago, Ill. The model 500 TV -FM antenna covers both television bonds and the FM band. The mounting bracket is de- signed to permit placement outside o window or in other places when a more drawers in any quantities at any roof installation is not possible. It is time and odd them to the old ones to form o larger cabinet. Each drawer has o small handle and a holder for an identification card. LIGHT A. C. SMALL SOLDERING HIGH -VOLTAGE TESTER GENERATOR IRON Richard Mattison Company Transvision, Inc., New York, N.Y, D. W. Onan & Sons, Inc., A test probe designed for television Minneapolis New Rochelle, N.Y. servicing, the Volter 5, Minn. weighs Hi- contains a mul- Series AAE gasoline- driven power The Soldetron only 3 ounces tiplier resistor. When used with any and has interchangeable heads. Push- plants furnish 350 watts o.c. and weigh v.t.v.m. having on input resistance button- controlled. it heats up in 20 only 77 pounds. They are small enough of 10 megohms, it will multiply the to fit into the trunk compartment of seconds from o cold start. It is oper- an automobile. ated from a 117 -volt a.c. line through a transformer, or from o 6 -volt battery. normal range of the meter by 10. It may also be used with a microam- mode for sets with a 300 -ohm input and meter by calibrating the meter scale will match the line correctly. directly in kilo -volts. The probe is insulated for 25,000 volts and hos a safety grip. The metal prod TV ANTENNAS is cadmium -plated. Network Manufacturing Corp., Bayonne, N.J. SOUND -EFFECTS KIT A new line of television receiving Winslow- Wright, antennas features elements made of I- inch -diameter aluminum tubing. Top North Hollywood, Calif. item is o three -element stacked array. Intended for home recordists. the Others range from simple dipoles up. Recordo- Script Producer's Kit includes Units for both upper and lower bands ten sound effects, such as bird calls, are available. In all, the large di- whistles, sleigh bells; etc.., three scripts; and a booklet on sound efects and how they ore created. Suitable for use with outdoor PA RADIO KITS systems, the generators are powered by Eagle Electronics, Inc. 4- cycle, air -cooled, cost -iron engines. All models Irvington. N. Y. (including those mode Pict -O especially for battery charging) hove -Graph kits include all the nec- electric push- button essary parts for making any of several starting. One different receivers, amplifiers, and model may be hooked to any auto phono oscillators. Each kit is accom- battery for starting; while it is run- panied by a pictorial wiring dia- ning, a special 6 -volt winding re- charges the battery. gram. ameter of elements gives good band The manufacturer claims that no width, and mechanical installation knowledge of radio is needed to con- HIGH -FIDELITY problems are at a minimum. struct the kits. The type LF -3E -D 3- element, double - Receiver kits offered range from a TRANSFORMERS stocked beam pictured is especially in- I-tube a.c. -d.c. set to a 5 -tube super- Standard Transformer Corp., tended for use with receivers in fringe heterodyne. Also available are 3- and 4- areas. The gain of the array is approxi- tube amplifiers, as well as a crystal Chicago, Ill. mately 20.5 db. It covers channels 2 receiver, a code -practice oscillator, The new Stoncor HF and WF series through 6. and a vacuum -tube voltmeter. RADIO -ELECTRONICS fo+ \ew_illevices 61 TWO -SIDE RECORD COMBINATION TESTER PLAYER Radio City Products Co., Inc., New York, N. Y. Markel Electric Products, Inc., The Model 8573 Servishop is a tube Buffalo, N.Y. tester, FM, AM and a.f. signal gen- a 50 -range multimeter. It Both sides of each disc ore played erator, and consists of the Model 805B combination by the Markel Dim Playmaster. The ÓAIN+++ tube and set tester combined with the db pickup has a cartridge with two styli, Model 730 generator. one below and one on top. After play- signal The tube tester is calibrated for over 800 types of tubes including those with more signal strength for greater acorn and sub -miniature type bases. Readable scale on the ohmmeter is from 0.05 ohm to 25 megohms in 5 ranges. Other ranges are: 0- 2.5- 10 -50- distance and the best picture 250- 1000.5000 volts d.c.; 0.10- 50 -250- 1000 -5000 volts a.c.; 0-.5-2.5-10-50-250- 1000 ma d.c.; 0.10 amps. d.c.; -8 to STACKED ARRAY ing the bottom record, the pickup moves up and plays the underside of the next one. Three rubber -tired wheels spin the top record and then, moving aside, ease it down to the turntable. +15, 15 to 29, 29 to 49, 32 to 55 db; ANTENNA CHIMNEY and output ranges corresponding to o.c. voltage ranges. MOUNT The unit's natural oak cabinet is Id /= x 123/4 x 5t/4 inches and its panel is JFD Manufacturing Co., hammertone gray. Weight 18 pounds. Brooklyn, N.Y. The odiustable chimney antenna mount consists of an angle bracket PHONO AMPLIFIER which rests against o corner of the Langevin Mfg. Corp. metal which chimney and a strap New York, N. Y. passes around the chimney. Two of ¡MODEL NO. 114 -301 is a conversion these mounts may be placed any dis- The Type 127 -A amplifier is designed kit for use in building Amphenol's tance apart to support ony mast from to operate with a radio tuner and a f No. 114 -005 Antenna into a STACKED inch to I/r inch in diameter. phonograph using LP microgroove, ARRAY -mounting casting and phas- V2 crystal, or variable- reluctance car- ing stub included. (Mounts on 11/4" tridges. It delivers 4 watts output with mast -not included.) $20.45 less than 5% total harmonic distortion DISC HOLE REPAIRER over the range of 50 to 15,000 cycles. MODEL NO. 114 -302 completo two bay stacked array (mounts Dunwel Sales Corp., Separate bass treble and volume con- on 11/4" trols ore provided. ^ mast -not included) including 75 ft. Chicago, Ill. The unit is in a hammertone gray of Amphenol twin -lead. $41.80 metal often cabinet, small enough to fit into Frequently -played records de- a bookcase or radio cabinet. velop an enlarged or chipped center hole, usually due to small maladjust- ments of the changer. The result is erratic changing and wavering pitch. The Dunwel record repair kit consists of a two -port tool and a set of eye- lets. The threaded end of one of the tool sections is passed through the rec- Stacked Array multiplies the universally acknowl- edged features of the Amphenol All -Channel TV Antenna (No. 114 -005). Stack to provide reception REMOTE CONTROL CONSOLE at greater distances -Stack for picture brilliance and General Electric Co., clarity-Stack for controlled TV reception. Provide Syracuse, N. Y. The Type EC-8 -A remote control unit, the TV Receiver with to designed to FCC specifications, per- the Best Antenna Produce mits remote operation of receivers and transmitters in land- mobile radio com- the Best Picture. Amphenol's Stacked Array is your munications systems. ord hole and tightened into the other assurance of top TV picture quality. section. This enlarges the hole and makes it perfectly round. Then a pair of eyelets is placed in the hole and the other ends of the tool sections are used as before. This tightens the eye- lets and leaves the record with a metal center hole. MULTITESTER Performance Charts Available It you are not now receiving the monthly Bradshaw Instruments Co., AMPHENOL ENGINEERING NEWS - you will want to request the September issue Brooklyn, N. Y. which included pattern and gain charts Model 30 Multitester has a single The unit is used to turn on plate for the Stacked Array. We will be glad to to rotary selector switch which controls all power to the transmitter and mute a mail it and place your name on our list ranges. Meter sensitivity on the volt- particular combination of station re- to receive future issues -write Dept. I3D. i age ranges is 1,000 ohms per volt, and ceivers. Voice signals are fed to the maximums are 1 250 volts a.c. and 1,000 transmitter Through a preamplifier with volts d.c. Two d.c. milliampere ronges automatic level control. The line am- are provided, 0.1 and 0 -100. Resistance plifier has two separately controlled may be measured in three ranges, with inputs, one for station receiver moni- AMERICAN PHENOLIC CORPORATION a maximum of 1 megohm. A decibel toring and the other for monitoring 1830 SOutit AvENUE CHICAGO 50 ILLINOIS scale reading from -10 to +57 db is auxiliary receivers. 54I provided. COAXIAL CABLES ANO CONNECTORS INOUSIRIAL CONNICIORS. 1I11INGS ANO Zero db equals 6 mw in The unit is 10 inches high, 14 inches 500 ohms. deep and may be rock mounted. CONDUIT ANTENNAS RADIO COMPONENTS PLASTIC FOR ELECTRONICS JANUARY, 1949 G2 Introducing 1949 TIME 9 DELAY RELAY Signal Corps 9 Jack Box Po stpaid 8C1366 or 366 Jack Box. Contains Mic. Jack, volume control, 5 position 2 24 volt, 200 ohms Resistance, approxi- gang rotary switch, 11 contact bayonet Brand COMMAND SET mately 1/50 of 1 second delay. plug and receptacle. All nicely a new type 8 -9 manufactured by Gaur. sembled in a neatly finished metal box dion Electric. Part No. 34464. Price, ACCESSORIES 33/16 "W s 43/8 "H s 23/16 "D. only 99c post paid. Lors of uses in the Hom shack, lab., or on mobile installations. A sensational boy at only 79e each, postpaid, or 10 for 56.95 postpaid. By Bendix r22 Poilpald RACKS .2 2 vo 11- Model 3616, makes an excellent Double Transmitter rack. Brond new B a ti-er y set up for on intercom. set. Contains 3 in original carton. No. FT. -226 only multiple type wafer switches, one panel 99c postpaid. type fuse one volume control, on mas- Triple receiver ack. No. FT- 220 -A. ai ter 2 pole double throw switch. onee lock Brand new type sending and receiving telephon original cartons, only Brand new, compact, spillproof built. 51.59 postpaid. in hydrometer, groupseveral together key, one local remote transmitter c n to get higher voltages Fully guaran- ingle pole switch, one 24 -volt trol, one teed. Shipped dry, odd 35c to cover with 2 Leoch Relay contacts. postage and handling, Antenna Relay PDStPáldI Antenna Relay Unit BC -442A or RE 2 /ARC -5. Originally used on Command Set ' SCR -274 '. Contains on antenna change -over relay, o 19' z milivolt me- ter, with on externals amp. thermo- couple. The meter scale reads R.F. NEW Prp current on linear scale calibrated 0 to IO. . A truly sensational buy at METERS / only 51.95 Brond new 3 0-3. DC oltmcter 2" round cote. Meter hot 450 ohms se 6/6 resistance 150 ohm, per alt'. 'Add Used primarily on aircraft & Marine AI)F (Sc each to cover postage and hand- Systems. Loop L(-21 -A contains an elec. eoa tra/ ling. tric motor and selsyn. 7 hest loops hast heen removed from salvage aircraft. hut B are guaranteed to be in excellent working Brand new Bowers D.C. Volt meter condition. 0 to 9 volts in 2' cose with 2 3/4" Shipped F.rps'as (Óllerr Flange each .99c Originally used with the command set Brand new Bowers D.C. Anmeter between Modulator BC456A and Con- 0 to 100 amp scales '600 ma. Contains 3, 24 volt trol Bos BC451A. movement with 100 amp shunt, PE -73 -C E other parts an excellent buy relays and same case as volt meter each .99e 2 95 at only $1.39 postpaid. Add 20e each to cover postage DYNAMOTOR r '- and handling PE -73 -C Dynamotor. gf Input 28 volts of 19 Stainless Steel tamps at 5000 RPM, 95 output 1000 volts at S 950 Recording Wire Postpaid .55 amps. Used but good. Triple remote control boa for Corn and Receivers SCR 274 N Series/. .006 Stainless Steel recording wire. New on o- (shipped express col- Equipped with 3 tuning dials, 3 volume riginal spools as used by Army and Navy re- lect) Used, 1. controls, and 6 selector switches. corders. Each spool contains at least a mile of steal at but in cellent condition, a wire. Con be used on standard wire recorders. only 51.50 ea. ' Add 25c to cover pos. toge and handling. N. SILVERSTINE CO. 6532 EAST McNICHOLS ROAD DETROIT 12, MICHIGAN (CIIIIIENCe.vert RADIO -ELECTRONICS for 63 Take Advantage of These Bargains 525 Feet S 95 Brand New 2r--- Telephone Wire 3 conductor braided insulated copper and steel telephone wire. it is of copper for conductivity and steel for strength. Worth at least 3c per foot, yet due to an exceptional buy we now offer it of less than lc per foot. n ¡Shipped express charges collect/ tededidm 3 CP I , Ind. Screen .95 3 DP I.A , Ind. Screen .95 3 FP 7 -A 1 35 3 HP 7 _ 1 45 add 25c each to cover postage and handling, 5 FP 7 1.75 5 CP 1 .1.95 5 BP 2.45 5 HP 2.45 add 35c each to cover postage and handling T 7 BP 7 2.65 comPlefe 7 CP 1 3.25 withnsmitter odd 40c each to cover on but postage and hondling¡ /Sh 95 OPa d °#Pess collect 9 GP 3.50 I Shipped express, charges collect,. TUNING CONDENSERS /R.P.M. Brand New in cartons. 4 Gang -13 -226 MMF /Sec. 99c ¡Postpaid¡ 2 Gang os pictured ¡Postpaid¡ 69c 1300 FT. 3 4MOTOR =1 HeavyDuty Cable s5 495 adE/5 Au New, All Postpaid Y89 1 8012 New 4 conductor 16 gouge rubber covered cable. Color Ideal for a beam rotor, plenty of power. Ori- ginally designed for 24 volt DC operation, but coded. Used by United Stoics easily converted, 110 volts AC. Complete Government as Field Telephone instructions included. Excellent for other 705-A 1.3 Coble. 1300 feet on steel reel. ,uses too. Brand new, surplus, guaranteed. F.O.B. Our warehouse Shipped motor freight or express shipping 1 211 .69 Add 40c each to cover postage and handling charges collect. All merchandise subject to prior sole, minimum order $1.00, hlo IMPORTANT! C.O.D. orders accepted. Michi- gan residents must add 3 State sales tax. JANUARY, 1949 641 Tcchnotcs. . - . . RCA 668X Radio - Television - Electronic A common trouble with this set gives all the symptoms of an open filter ca- Parts & Equipment Specials. pacitor. If a check shows that the filters are good, replace the selenium rectifier TELEVISION- CATHODE RAY HIGH with a new 100 -ma unit. VOLTAGE TEDD FISHMAN, 2000 volt D.C. Power Supply Brooklyn, N. Y. For an unbelievably low price, we can supply a completely filtered television or cathode ray 2000 volt D.C. power supply. Why bother with bulky and dangerous 60 cycle supplies or ex- . . SILVERTONE 3351 pensive R.F. power supplies when you can purchase a complete 2000 volt D.C. unit (not The set was intermittent while in the a kit), reedy to plug into the 110 volt A.C. case but was satisfactory when removed power line. The ridiculously low price has been made possible by a fortunate purchase of high from the case. The trouble was a frayed quality components. These units are brand antenna wire which was shorting to new, completely tested and guaranteed. chassis. A short piece of spaghetti over Price $7.95 the lead cured the fault. 4000.6000 VOLT TELEVISION SUPPLY ROBERT J. ZELLNER, Similar to the unit above, but has a much higher D.C. output voltage suitable for use Menominee, Mich. with the new 7" and 10" television tubes. PRICE 312.50 GE MODEL 140 RADIO NOISE FILTERS ... Eliminates extremely noisy radio reception due to *PRACTICAL DISC If this set operates satisfactorily power line disturbances caused by lights, refrigerators. washing machines, vacuum cleaners, elevators, oil on batteries but not on a.c. or d.c., check burners, diathermy machines, etc. Filters out man -made noises in the broadcast, short- the 3S4. When the switch is in the wave. and ultra -high frequency bands. RECORDING Designed for all radios, appliances, and electrical battery position, the two halves of the equipment consuming up to 1300 watts (12 amperes tube's filament are paralleled, so the at 120 volts AC or DC. Answers Your Questions Housed in a metal case 1.á'x r X 71/2' complete set will operate even if one end of with male and female line connectors the filament is open. On the line, how- PRICE ONLY $2.25 LATEST INFORMATION Industrial Type Radio Noise Filter-Will handle up ever, the filaments are in series, and to 50 amperes. Housed in shielded case 3%" x 33/4" 5 Here is the book that thousands of radio en- 2", ". thusiasts have been waiting for. the tube will not work with half of the PRICE 33.95 Whether you're interested in amateur or pro- filament open. fessional recording, you'll find PRACTICAL T. HORIUCHI, EASILY ASSEMBLED RADIO KITS DISC RECORDING by Richard H. Dorf in- 5 Tube AC-DC superhet kit furnished in a valuable. It not only tells you how to make Rock Springs, Wyo. brown plastic cabinet of artistic design, cab. successful records, but in addition each im- inet size (9"x5 "x6 ") portant recording component is given a full Variable condenser tuned ; with 2 double tuned chapter, explaining its purpose, and what fea- PHILCO AUTO RECEIVERS I. F.'s. tures to look for when buying. Tubes used: 1 12SA7, 1 - 12SQ7, 1 - 12SK7 When resistance or voltage this book many reasons. With- measure- 1 - 35Z5 and 1 - 50L6 You'll like for out waste of words, it gets right down to ments show an open i.f. coil, remove the PRICE $11.95 standád tuwa business on the first page. It tells you what assembly from the can and examine the you need to make good records and how to TUBE 3 WAY PORTABLE KIT 6 do it by using any type equipment-from the lugs for broken -off leads frequently For operation on 110 volt AC or DC and simplest to the most expensive-depending on caused by vibration. A careful resolder- battery your purpose and pocketbook. You will find Superheterodyne circuit all the practical phases of recording covered ing of the wire to the lug will make the Full vision dial as principles. High gain loop well as the underlying transformer as good as new. Cabinet of Blue Aeroplane cloth finish, HURLE' D. ROBINSON, size 13x9^/ x7" FILLED WITH FACTS Tubes used 1A7, 1H5, 3Q5, 117Z6 and Pullman, W. Va. Chapter 1 discusses the various components 2 . INS which make up the complete system. Chapters P -RICE $13.75 Extra °ion " °1',"r tubeaa $3.75 2 to 5 go into the practical details of the PHILCO 48 -200 selection and use of discs, motors and turn- .. 6 TUBE, 2 BAND SUPERHET KIT tables, feed mechanisms and cutters. Chapter If one or several stations fade in and Bands covered BC 550-1600 KC and 6 -I8 MC 6 is a comprehensive explanation of constant out on this set, replace the oscillator Power supply 105.125V AC. DC velocity recording, the Full vision dial amplitude and constant coil. Variable condenser tuned, with two double tuned two fundamental recording characteristics on If that does not entirely cure the I. F.'s 455KG which all recording is based Chapter 7 covers trouble, install the ceramic trimmer sold Walnut veneer wood cabinet stylus selection. In Chapter 8 the various PRICE $15.75 sound sources (microphones, radio tuners, etc.) by Philco for this purpose. are discussed. A feature is the handy chart JOSEPH \VOLK, of characteristics of different types of micro- A SCIENTIFICALLY DESIGNED phones. Chapter 9 discusses the all- important Brooklyn, N. Y. PHONO SCRATCH FILTER amplifier. Circuits of several practical ampli- Resonated at approximately 4500 cycles effectively fiers are given. In Chapters 10 thra 13. you'll reducing obi eeti onable needle scratch without alter. find explained the detailed techniques of mak- .... RCA RECEIVERS Ing the brillancy of reproduction. ing good records. All the fine points of ad- Contains a HI -Q SERIES resonated circuit. Tested The condensers in certain RCA re- by means of an audio oscillator and an oscilloscope justment, equalization, microphone placement to give 22 db. attenuation with very low signal loss. and microphone technique, and a whole chap- ceivers were assembled with a compound EASY TO ATTACH ter on dubbing. Chapter 14 is a concise sum- Just two wires to clip on. Compact ;1.98 mary of common troubles in recording, and in each end to hold the wires against Price how to overcome them. The book ends with the foil inside. This compound loosens, THREE TUBE PHONO AMPLIFIER a comprehensive glossary of recording terms. creating poor contact with the foil. The An assembled unit ready for Installation using tone and volume control and six feet of rubber $2.95 96 PAGES. 82 ILLUSTRATIONS condensers that have failed in a receiver cord sng Tubes) must be replaced, but cost usually pre- With Complete Set Tub 33.95 vents replacing the rest. I paint the ends PHONO OSCILLATOR Only 75c of each condenser with service cement Wireless phono oscillator transmits recording for Postpaid. crystal pick -ups or voice from carbon mike through See your radio parts jobber today or order to prevent their failing during my guar- radio without wires. Can also be used as an intercomm by using P.M.'speaker as mike. Price direct. antee period. (excluding 2.95 SEE COUPON BELOW ALAN SMITH, With CompletepleteSet of Tubes 33.95 CLIP AND MAIL Shaftsbury, Vermont. SPECIAL! SPECIAL! RADCRAFT PUBLICATIONS, INC., Mammoth assortment of radio and electronic Dept. 1 -49 parts, not less than TEN POUNDS of new 25 West Broadway, New York 7. N. Y. . . PHILCO 46 -1201 transformers, chokes, condensers, resistors, switches, coils, wire, hardware, etc. A super - Send me PRACTICAL DISC RECORDING Many of these sets develop a loud buy for experimenters, service- $1.25 I enclose 75c. The men, and amateurs for only hint, either steady or intermittent. Satisfaction guaranteed on all merchandise. Your Name radio -phonograph change -over switch All prices F.O.R. New York City (Print clearly) has a metal snap -on cover which may WRITE FOR FREE CATALOGUE Address be loose. Retighten and bond it to keep intact. RADIO DEALERS SUPPLY CO. Jobber's Name the shielding A. G. SANDERS, 154 Greenwich St. 'New York 6, N. Y. Address e Miami, Fla. RADIO- ELECTRONICS for Technotes 65 .... I.F. TRANSFORMERS A resistance check across the i.f. coils of a weak receiver showed as much as 3,000 ohms. The transformers were found to have corrosion under the first winding layer. Replacement was neces- sary. PETER KACAOURA, Jamaica, N. Y. .... TUNABLE HUM Tunable hum in a.c:d.c. receivers whose grounds are not connected direct- ly to the chassis can often be traced to the a.v.c. bypass capacitor. If this capa- citor is connected to the chassis, unsol- NEW Television Kits and Equipment der it and hook it to the circuit ground. Important Advances in TV Reception and ALAN SMITH, Servicing! Shaftesbury, Vt. NEW 10" TV KIT 3526 REPLACEMENT at amazingly LOW PRICE! The 35Z6 rectifier used in several of The now Transvision Model 10A electromagnetic TV Kit the older makes of receivers is no longer gives a bright. stable 52 sq. In. picture. Has 10- picture tithe. and CONTINUOUS TUNING on all 12 channels. Ito being manufactured. Replace bad ones high sensitivity makes for improved long -distance reception: especially good on high channels. Complete with all -channel with a 25Z6 plus a 33 -ohm, 5 -watt series double- folded dipole antenna and 60 ft. of lead -in wire. dropping resistor. MODEL 10A TV KIT. less cabinet Net 9199.00 MODEL 12A TV KIT, same as ahove, but has D. H. EBERT, a 12e picture tulle Net $263.00 Chicago, Ill. MODEL 10A TV KIT NEW STREAMLINED CABINETS for Transvision Model l0A or 12A TV Kit. Made of select .... ADMIRAL 7C63 grain walnut with beautiful rubbed finish. Fully drilled, ready for installation of assembled receiver. These sets are frequently brought in Walnut Cabinet for 10A or 12A (Specify) Net $44.95 with a complaint of low volume. Some- )Iahogany and Blonde slightly higher. times the set is dead. Begin by checking the twin lead connecting the two halves TRANSVISION ALL- CHANNEL of the loop antenna. It is fastened to TELEVISION BOOSTER the cabinet with staples, which, in some To assure television reception in weak signal areas, or areas which are out of range of certain broadcast stations. cases, short the loop. To prevent future Transvision engineers lace designed this new booster. It increases signal strength On all television channels. Tunes trouble, remove the offending staples all television channels continuously. Can be used with any type of television receiver. Unusually high gain in upper and replace them with ones small television channels. enough not to short the wires. Model B -1 LIST 944.95 D. L. FUQUA, Fairfield, Iowa TRANSVISION REMOTE CONTROL UNIT KIT REMOVE OLD CONDENSERS ALL -CHANNEL BOOSTER .... Will operate any TV receiver from a distance. Turns sat When new power- on. tunes in stations, controls contrast and brightness, turns installing supply set off. Ideal for installations where the telerision receiver filter condensers in a receiver, it is very is inaccessible. Tuner unit is a high gain. all-channel unit with about 50 micro-volt sensitivity. Easy to assemble in bad practice to leave the old ones in about an hour. place. They may down Model TRCU, with 25 feet of cable NET $69.00 eventually break Without cabinet NET 965.00 and short out. Remove or disconnect them. TRANSVISION TELEVISION AND FM Removal of certain types of conden- SWEEP SIGNAL GENERATOR sers benefits the serviceman in other Complete frequency range from 0.227 MG with no band switch- ways. Old aluminum cans, for instance, ing. Sweep width from 0 -12 MC completely variable. Ac curately calibrated built -In marker generator. are useful around the shop as r.f. ADDITIONAL FEATURES: I11 Dial eallbranvl in fre- on probes, tube shades. quency. . . (2) Self- contained markers readable directly shields, night-light the dial to .5% or better. (No external generator required to and ballast housings. provide the markers signale).... (3) Cantal controlled output makes possible any crystal controlled frequency from 5 -230 R. P. BALIN, MC. . (4) Plenty of voltage output- permits stage -by- stage alignment.. . (51 Outing impedance 5 -125 ohms. . Miami, Fla. (6) Directly calibrated markers. 20 -30 MC for trap. sound REMOTE CONTROL UNIT KIT and video IF alignment. . (7) SF for alignment of ZENITH 6MF080 FORD traps for IF channels when a DC volt meter is used as the .... indicating medium. . . (8) Unntodulated 1IF signal to I have serviced five of these auto sets, provide marker pips simultaneously with the main variable oscillator. . . . (9) Markers can be controlled as to output of low vol- strength In the pip oscillator. . (10) Power supply cont- all with the same complaint pletely shielded and filtered to prevent leakage.. .I11) All ume and intermittent reception. Replac- active tulles are the new modem miniature type. . . . (I21 Phasing control incorporated in the generator. ing the coupling capacitor between the MODEL NO. SG. Net 999.50 7B6 plate and the 7C5 grid with a 1,000 -volt unit of the same value cured Ì RADIOMEN . . . You Can GET INTO The the trouble in each case. The sensitivity I control usually needed adjustment, too. DAVID H. HORN, TELEVISION BUSINESS Miss. . Grenada, IN A BIG WAY WITH THE .. . INTERMITTENTS TRANSVISION DEALER PLAN One cause of intermittents is ground Write for FOLDER D -i lugs riveted to the chassis. These some- SWEEP SIGNAL GENERATOR times loosen up enough to cause resis- NEW 8 -PAGE CATALOG showing complete Transvision line now available at your distributor, or write to tance. To fix them permanently, solder them securely to the chassis. TRANSVISION, Inc. Dept. RE New Rochelle, N. Y. L. E. MEYERS, In Calif.: Transvision of California. 8572 Santa Monica Hlvd.. Hollywood It. Prices Subject to Change W ithrut N et( re, Ironton, Ohio \ All prices 5% higher west of Mississippi: all prices fair traded. All JANUARY. 1949 cc . ó for the best in TELEVISION C Q o for CUSTOM-BUILT installations 20 INCHES IONCH .Ai 520 S ERICTURf 26 INCHES t -0 PROJECTION TELEVISION ""%;;" ' r Bausch p Lomu Cscecal Electronic System provides a contrasty sparkling picture projected onto the Eastman Kodak Giass Froíection Screen, completely glare -proof. Every part of the entire set is designed. engineered and manulaLtured tor the express purpose of bringing you the tinest in television ... If ready for CUSTOM -BUILT installations in homes, schools, lodges. clubs. hospit.:ls, taverns and other public places. 10" 12" 15" TUBE BAUSCH & LOMB F:1.9 PROJECTION or LENS TELEVISION RCA 5TP4 PROJECTION C. R. TUBE in easy to install units PRE -WIRED 21.30 KV TRIPLER FLYBACK POWER SUPPLY ALUMINUM COATED FOP PROJECTION MIRROR EASTMAN KODAK GLASS PROJECTION SCREEN PRE- WIREO. PRE -TUNED I. F. PICTURE & SOUND STRIP (PAT. PEND.) DUMONT INPUTUNER all channels- MI FM Radio RCA 12 HIGH FIDELITY PM SPEAKER STANDARD MANUAL OF INSTRUCTIONS & SCHEMATIC MODELS 30- tubes, including the C.R. DATA prepared & edited by renowned Tube. Supplied with 13 -tube JOHN F. RIDER PUBLISHER. INC. I.F. Picture and Sound Strip (Pat. Pend.) completely PICTURE MODEL P -520 COMPLETE WITH RACK. H000 & wired, tubed, tested and FRAME aligned. Has standard tuner pre -wired to handle 13 chan- nels, ready to use with above unit. Here's why Television Experts praise T.A.C. Television TELEVISION ASSEMBLY CHAMPION MOORS Our products contain every new development, COMPANY GUARANTEE every new creation of television research. Our All components are of the finest WITH quality and are fully guaran efforts are bent towards quality and this is par- teed under the Standard RMA DUMONT INPUTUNER ticularly evident in the performance of our Guarantee. All TAC Assemblies 'ore guaranteed to operate when Gives continuous tuning for Assemblies. That's why men who know tele- assembled-according to oll 13 channels plus all vision are telling others about T.A.C. supremacy. directions. FM Rodio. Available for all tube sizes. Smart, Modern Available only through Hand -Rubbed National Parts Distributors Walnut & Blonde It C EVISO tl Write us for list Cabinets for 10" Write for literature 12" or 15" tube chassis Our own exclusive designs, avail. tt 0 Ave., N. Y. ASS E1I I l 540 Bushwick B'klyn 6, able for all T.A.C. models. Details on request. RADIO -ELECTRONICS for 67 Check this list for your nearest Television Assembly Co. Distributor CAL IFOR N I A- Berkley DELAWARE-Wilmington MINN ESOTA -M inneapol is NEW YORK -Flushing OREGON-Portland Dealers Supply Co. Almo Rodio Lew Bonn Co. Milo Rodio & Electronics Corp. Portland Radio Supply Co. Grove 8. Addison Sts. 6th and Orange 1211 la Salle Ave. 160.13 Northern Blvd. 1300 W. Burnside St. CALIFORNIA -EI Monte WASHINGTON, D.C. MONTANA-St. Louis NEW YORK- Fredonia United Radio Supply Co. El Monte Electronics Sup. Co. Allied Electronics Radionics C. R. Barker 22 N.W. 9th Ave. 992 E. Valley Blvd. #3 Thomas Circle 5040 Eastern Ave. 45 W. Main St. PEN NSYLVAN IA-Allentown CALIFORNIA -Glendale Capitol Radio Wholesalers Inc. NEW HAMPSHIRE -Portsmouth NEW YORK- Hempstead R. & M. Sales R. V. Weatherford Co. 2120 -22 14th St. N.W. Electronics Lab. of N. H., Inc. Island Radio Distributing Co. 1157 E. Livingston St. 6919 San Fernando Rd. Electronic Wholesalers Inc. 154 Congress St. 412 Fulton Ave. PEN NSYLVAN IA- Attoona CALIFORNIA-Hollywood 2010 14th St. NEW JERSEY -Belleville Standard Parts Corp. Kennedy's Radio Supply Hollywood Radio Supply Kenyon Rodio Wallace & Tiernan Co. 235 Main St. 1500 Seventh Ave. Hollywood Blvd. 2214 14th St. N.W. 1 Main St. 5606 NEW YORK -Jamaica PENNSYLVANIA -Erie NEW JERSEY- Camden Pacific Rodio Exchange, Inc. Northwest Radio Wholesalers Harrison Radio Corp. J. V. Duncombe Co. General Supply Co. 1407 Cahuengo Blvd. 3162 Mt. Pleasant St. N.W. 172 -31 Hillside Ave. 1011 W. 8th St. 207 N. Broadway CALIFORNIA -Long Beach Rucker Radio Wholeso lsrs, Inc. Norman Rodio Dist. Radio Electric Service Co. PEN NSYLVAN IA- Lancaster Fred S. Dean Co. 1312 14th St. N.W. 94 -29 Merrick Rd. D. Barbey Co., Inc. 513 Cooper St. The George 969 American Ave. Sun Radio Peerless Rodio Distributors 29 East Vine St. NEW JERSEY- Cliffside Park Lynde Radio Supply Co. 938 F Street N.W. 92.32 Merrick Rd. lorry Nidisco Cliffside Pork, Inc. PEN NSYLVAN IA- Norristown 853 Pine Avenue ILLINOIS- Chicago 658 Anderson Ave. NEW YORK - Jamestown Kratz Brothers Scott Radio Supply Concord Rodio Johnson Radio & Electronic Equip. Cor. Kohn & Oak Sts. NEW JERSEY -Clifton 266 Alamitos Ave. 901 W. Jackson Blvd. 48 -50 Harrison St. Eastern Radio Corp. PENNSYLVANIA-Philadelphia CALIFORNIA -Los Angeles Newark Electric Co. 637 Main Ave. N EW YORK- Middletown A & G Rodio Parts 323 W. Madison St. L S Radio 3515 North 17th St. Kierolff & Co. NEW JERSEY -East Rutherford & Sales 820.830 W. Olympic Blvd. INDIANA-Indianapolis Bergen Supply Co. NEW YORK -New York City Almo Rodio lea J. Meyberg Co. Van Sickle Rodio Co. Route 17 & Stanley St. Arrow Electronics 509 Arch St. W. 2027 S. Figueroa St. 54 Ohio St. NEW JERSEY -Jersey City 82 Cortlandt St. Herbach & Rademan Co. Rodio Ports Sales Co. IN D IANA-Logansport Nidisco Jersey City, Inc. Federated Purchaser, Inc. 522 Market St. 5222 S. Vermont Ave. A. E. Conrad Co. 713 Newark Ave. 80 Park Place Penn Electronic Parts Co. Rodio Products Sales Inc. 508 Broadway NEW JERSEY -Newark Fischer Distributing Co. 5303 Frankford Ave. 1501 S. Hill St. IOWA -Des Moines Continental Sales Co. 118 Duane St. Radio Electric Service Co. 195 -197 Central Ave. Rodio Specialties Co. Rodio Trade Supply Co. Harrison Rodio Corp. N.W. Cor. 7th & Arch Sts. 1956 S. Figueroa 1274 Grand Ave. Krisch- Radisco 12 West Broadway PENNSYLVANIA-Pittsburgh 422 Elizabeth Ave. Universal Rodio Supply Co. I There's a Television Assembly Co. Distributor near you! Check this list JANUARY, 1949 68 WOrld - lYide- Statio-1 List I for the best in By ELMER R. FULLER ELEVOSKIN TELEVISION Location station Freq. Sehedula F ALBANIA for CUSTOM -BUILT Tirana IAA 7.850 1300 to 1630 ALGERIA MIRY ED. Constantine 11.830 0130 to 0315; 0630 to 0915; 1315 to 1400; 1430 to 1700 installations ANDORRA 5.980 0600 to 0830; 1300 to 1900 ANGOLA Benguela CR6RB 9.160 1300 to 1430 Louanda CR6RA 9.470 0115 to 0230; 0630 to 0745; 1400 to 1530 MODELS ARGENTINE STANDARD and CHAMPION Buenos Aires LRSI 5.980 1800 to 2300 Buenos Aires LRYI 6.090 0645 to 2100 Buenos Aires LRAI 9.680 0800 to 2200 with 10 -inch, 12 -inch, 15 -inch Tubes Rosario LRR 11.880 0900 to 2100 AUSTRALIA Melbourne VLH3 9.580 0345 to 0830; Sut., PROJECTION MODEL 0245 to 0900; Sou.. Distributed by P520 0330 to 0830 Melbourne VLG3 11.710 0295 to 0345 Melbourne VLG3 15.230 2330 to 0045. 0100 to 520 inch PICTURE 0145; 2200 to 5300: Sat. and Sun., 2100 to 2300 Perth VLW7 9.520 0530 to 1030; 1600 to RADIO 1900 Melbourne VLR 9.540 0800 to 0915; 0930 to DISTRIBUTORS 1000: 1245 to 14,5 Shepparton VLC6 9.610 1000 to 1115; 1500 to 1015 Shepparton VLC7 11.840 2330 to 0045; 1500 to 1615 Shepparton VLC4 15.310 0245 to 0345; 0355 to 0730; 0800 to 1045 AUSTRIA Vienna KW54 7.160 2345 to 2030 Vienna 9.560 0000 to 11200: 0400 to FULTON AVE. 0830; 1000 to 1600 412 Vienna 11.780 2345 to 1005 Vienna 12.210 2345 to 1800 AZORES LONG ISLAND, NEW YORK Ponta del Gada 11.090 1500 to 1600 H EMPSTEAD BELGIAN CONGO Leopoldville OQ2RC 6.010 1200 to 1300 Leopoldville OTC 9.380 0000 to 0200; 1100 to 1500 Leopoldville OTC 9.740 1530 to 1645; 1700 to 2300 Leopoldville OTC 11.720 0530 to 0739 Leopoldville O 02RC 15.320 1200 to 1"00 Leopoldville OTC 17.770 0500 to 0930; 1130 to 1215 BOLIVIA Cochabamba CP40 6.510 1930 to 2200 DISTRIBUTORS for La Paz CP49 6.770 0700 to 0900; 1100 to 1200; 1730 to 2100 BRAZIL In Buffalo, N.Y. Belem P RC5 4.860 n800 to 0700; 0900 to 1100; 1720 In 2000 ex- cept Sundays Fortaleza PRE9 6.110 0'100 to 1200: 1000 to 1900 Rio de Janeiro ZYC8 9.610 1500 to 2200 U TEdE DUE Rio de Janeiro PSH 10.220 1700 to 1800 Here are the Rio de Janeiro P R18 11.720 0345 to 0700 Sao Paulo ZYB7 6.090 1000 to 2150 Sao Paulo PST2 7.410 except Saturdays and Sundays, 1800 to 2000 2 GREATEST NAMES MERd E BRITISH GUIANA Georgetown ZFY 6.000 0545 to 0745; 0945 to 1145; 1415 to 1945 BRITISH SOMALILAND in TELEVISION Hargeisa VQ6MI 7.130 0800 to 1030; 1200 to 1300 BRITISH WEST INDIES Jamaica 201 3.480 1R00 to 2200 CUSTOM -BUILT Jamaica Z01 9.950 1600 to 1730 for BULGARIA Sofia 0.330 2300 to 0100; 0530 to 8700; 1100 to 1330; CUSTOM -BUILT 1400 to 1545 TELEVISION BURMA Rangoon 6.040 0915 to 1015 INSTALLATIONS CAM EROONS in Douala 7.950 1300 to 1500 CANADA Calgary CFYP 6.030 0730 to 0100 Edmonton CJCA 9.540 0815 to 0200 Montreal CFCX 6.000 0700 to 2315 SAN FRANCISCO Montreal CBFW 6.090 0730 to 1945; 2000 to TEL 2400 Montreal C K LO 9.630 1600 to 1800 CALIFORNIA Montreal CKCX 15.190 0845 10 1100; 1820 to QSSEELY ED. 1935 Montreal CKNC 17.820 1345 to 0100; 0845 to 0030; 1820 to 1100 Toronto CFCX 6.070 0000 to 0030 Vancouver CKFX 6.080 0930 to 0300 AND Vancouver FBRX 6.160 0900 to 0200 Winnipeg C190 6.150 2200 to 0300 Winnipeg CK RX 11.720 1000 to 2000 CANARY ISLANDS Santa Cruz EA143 7.570 0730 to 0900; 1230 to 1700 CAPE VERDE ISLANDS RADIO Praia ASSOCIATED CR5AA 1530 to 6.400 1700 CEYLON RADIO Colombo SEAC 3.390 0730 to 1200 ELECTRIC Colombo ZOH 4.900 2100 lo 1145; 0100 to 0330; 0630 to 1200 DISTRIBUTORS Colombo 6.070 1930 to 1200 PRODUCTS INC. Colombo SEAC 9.520 1930 to 1200 1251 FOLSOM ST. SAN FRANCISCO 3 Colombo SEAC 15.120 1939 to 2300; 2330 to 677 Michigan Ave. 0500; 0700 to 1200 TELEPHONE Colombo SEAC 17.770 2300 to 0730; 1100 to HEMLOCK -10212 1200 BUFFALO, N. Y. Colombo SEAC 17.820 1930 to 0135; 0500 to 0700; 0715 to 1115 RADIO-ELECTRONICS for World -Wide Station List I 69 Location Station Free. Sehedule CZ EC H OS LA VA K IA Prague 9.550 1215 to 1230; 1315 to 1330; 1400 to 1430; 1445 to 1500; 1515 to 1530; 1600 to 1630; 1645 to 1700 Prague 1030 1100; 1115 to IN 11.840 to PHILADELPHIA 1130; 1200 to 1215; 1295 to 1300 Prague 15.230 1800 to 1900 CH ILE Santiago CE622 6.220 1900 to 2030 Santiago CE1174 11.740 1700 to 2400 and WILMINGTON Santiago CE1180 12.0110 0600 to 0800; 1600 to 2300 CHINA Canton XTPA 11.650 0400 to 0830; 2200 to 0030 Chungking XGOY 7.150 0530 to 0730; 0745 to 0945; 1000 to 1043 ItS Chungking XGOY 11.900 0040 to 0530; 0745 to 0830; 0893 to 1045 Foochow XGOL 10.000 0400 to 1000 Kweiyang XPSA 7.010 2330 to 0030; 0430 to U900 Shanghai XORA 11.690 0500 to 1000 COLOMBIA Armenia H1FH 4.880 0600 to 2200 RADIO CO. Barranquilla HJAB 4.780 1700 to 2255 Bogota H1CA 4.850 1900 to 2200 Bogota HIGH 4.890 1800 to 2200 509 ARCH STREET Bogota HJCW 4.940 0645 to 1115; 1600 to 2315 MODEL P H I L A D E L P H I A , PA. Bogota H1CQ 4.950 1000 to 1400; 1700 to P -520 2300 Bogota H1CX 6.020 0700 to 0800; 1400 to Corner SIXTH and ORANGE Streets 2315 520 SQ. INCH Bogota H1CD 6.160 0700 to 0800: 1600 to WILMINGTON, DELAWARE 2330 Bogota H1CT 6.300 1000 to 1400; 1800 to PROJECTION 2313 Bogota HJCF 6.240 1700 to 2300 Cartagena HJAP 4.910 0600 to 1300; 1700 to TELEVISION 200 Cartagena HJAE 4.960 1600 to 2230 Cali HIED 4.820 1900 to 2300 Cucuta H1BB 9.810 1700 to 2200 TELEVM Medellin HIDE 6.140 1100 to 2300 10",12 ",15" COSTA RICA San Jose TIRH 6.150 2130 to 2400 San Jose TIPG 9.610 0700 to 2330 PICTURE TUBE CUBA Camaguey COJK 8.720 2000 to 0030 STANDARD AND o Havana COBF 6.040 0800 to 2300 H avana COCD 6.130 0700 to 2400 CHAMPION MODELS Havana COCW 6.330 0600 to 2400 Havana COCO 8.700 0700 to 2330 Havana COCQ 8.830 0530 to 0030 TELEVISION ASSEMBLIES Havana COBZ 9.030 0700 to 0100 Havana COBQ 9.230 0800 to 1100; 1730 5, 2330 Havana GOCX 9.270 0700 to 0030 Havana COBL 9.830 0715 to 0045 for the best in TELEVISION for CUSTOM -BUILT H nana COCY 11.740 0530 to 2330 installations Santa Clara COHI 6.430 0630 to 2400 Santiago COKG 8.950 0600 to 2300 CU RACAO Willemstad 9.970 1400 to 1600 Willemstad PJCI 7.250 1130 to 1230; 1630 to DISTRIBUTORS 2130 DENMARK FOR openhagen OZF 9.520 1145 to 1545 DOMINICAN REPUBLIC for the Best in Ciudad Trujillo 1112T 5.970 1900 to 2400 LARRY Ciudad Trujillo HUN 6.240 1600 to 2250 Ciuoad Trujillo HIIZ 6.310 1600 to 2255 Ciudad Trujillo HI2G 9.210 0530 to 0830. 1300 to TELEVISION 1530; 1700 to 1645 ECUADOR LYNDE Ciudad Cuenca HCSEH 3.930 1800 to 2230 Quito HCJB 4.100 1800 to 1230 for CUSTOM -BUILT Riobamba HC5HC 4.930 1800 to 2300 RADIO Quito HCJB 5.970 0000 W 0200 Quito HCJB 6.280 1800 to 2400 DIRECT -VIEW installations Quito HCJB 9.960 2230 to 2900 except SUPPLY CO. and Mon.; Mon, 2300 to 0300; Bun, 0800 to PROJECTION 2150 Quito HCJB 12.440 1400 to 2230; Mon.. 853 PINE AVE. ASSEMBLIES 2230 to 2900 Quito HCJB 15.110 0500 to 1200; 1330 to for 2230 Long Beach, EGYPT Calif. CUSTOM-BUILT Cairo SUX 7.850 1400 to 1920 ENGLAND TELEVISION TELE uV London GRR 6.070 2300 to 0030 London GSL 0.110 2300 to 0215; 1615 to 1745 London GRW 6.150 1515 to 1600; 2000 to 2215 TELEVISION ASS o Landon GRM 7.120 1145 to 1215; 1445 to EModYE 1715; 2330 to 2345 London GSU 7.260 2315 to 2330; 2345 to 0130; 1000 to 1700 fL2 London GSC 9.580 1330 W 1345; 1930 to 1530; 1600 to 1613; 10-12 and 15 inch Tube 1615 to 2030 London CRY 9 G00 2300 to 0100: 1315 to HEADQUARTERSHEADQUARTERS 1600; 1800 to 2245 for and London GWO 9.620 1830 to 2300 London GVZ 9 640 0100 to 0400; 0600 to PROJECTION and DIRECT VIEW 1045; 1615 to 1745 Sq. In. Picture Projection London G R H 9.820 1830 to 2300 CUSTOM - BUILT TELEVISION 520 London GVW 11.700 2300 to 0030 London GSD 11.750 2000 to 0300; 1215 to 1745 Assemblies London GSN 11.820 0100 to 0500; 1230 to RADIO PARTS SALES CO. 1600; 1800 to 2030 London GRF 12.090 2300 to 1615; 1700 to 5220 -22 So. Vermont Ave. 2030 London GWG 15.110 0400 to 1600; 1800 to Los Angeles 37, Calif. 1930 London GSF 15.140 0600 to 0715; 0915 to 1015; 1030 to 1200; 1300 to 1600; 1615 to 2015; 2300 to 0100 DISTRIBUTORS for London OSO 15.180 1300 to 1600 1615 to in 2015 London GS! 15.260 0100 0500; TEILVISION Products ZACK to 1615 to 1845 CALIFORNIA London GWR 15.300 1200 to 1315 ASSEMBLYTEl. C0. RADIO SUPPLY CO. London GSP 15.310 1045 to 1315; 2395 to E. WENGER 0030 C. CO. 1426 MARKET San 2, London GRD 15.950 0100 ST., Francisco Calif. to 0500; 1700 to 1450 HARRISON ST., OAKLAND 12, CALIF. 2030 225 HAMILTON AVE., Palo Alto, Calif. London GVP 17.700 0600 to 0900; 1700 to 881 S0. FIRST ST., SAN JOSE, CALIF. 1800 JANUARY, 1949 70 World-Wide Station List Location Station Freq. Schedule GOLD COAST Accra ZOY 7.290 1045 to 1300 for the best in TELEVISION GUATEMALA Guatemala City TG2 6.610 1800 to 2300 Guatemala City TGWA 9.670 1830 to 2330 lE4EylS9 M Guatemala City TGWA 15.170 0730 to 1500 HAITI for custom -built Port -au- Prince H H2S 5.950 0600 to 0815: 1100 to 1300; 1730 to 2130 Port -au- Prince HHCM 6.000 1200 to 1400; 1830 to 2100 ASSEMBLY El Port -au- Prince HHCM 6.160 0500 to 0830; 1100 to INSTALLATIONS 1400; 1700 to 2145 HAWAII Honolulu K RHO 15.250 0100 to 1005 Honolulu K RHO 17.800 0230 to 0345 (off Mon- days) HONDURAS La Ceiba HR02 6.230 1200 to 1400; 1900 to 2300 the FamousT.A.C. Model P -520 San Pedro Sula HRPI 6.360 1100 to 1415; 1800 to MALZ PRESENTS 2330 Tagucigalpa H RN 5.870 0800 to 1000: 1300 to 1500; 1800 to 2300 ICELAND Roykjavík IFI 11260 Sundays. 0900 to 0930 PROJECTION TELEVISION INDIA Delhi VU D3 3.340 1100 to 1240 Deihl VUD3 6.100 1200 to 1245 Delhi VUD3 7.290 0800 to 1100; 1730 to neu Sq. Inch Picture) 1825; 2100 to 2300 ASSEMBLY Delhi VU D5 9.590 0900 to 1230 Delhi VUDII 15.290 2215 to 0030; 0125 to and o Complete Line of TELEVISION ASSEMBLY CO. PRODUCTS 0150; 0200 to 0400; 0500 to 0700 Delhi VUDIC 17.830 0430 to 0700; 0745 to 0800; 2215 to 0215 INDO -CHINA Saigon 11.780 1830 to 2000 IRAN Teheran EQB 6.150 0930 to 1400; 2230 to MALZ ELECTRIC CO. 2315 Teheran EQC 9.680 1200 to 1430 Tabriz 11.690 0500 to 0700 690? "5'T. CLAIR AVE. CLEVELAND, OHIO ITALY Rome 6.080 EN -4808 1400 to 1700 TELEPHONE: Rome 9.630 1400 to 1700; 1715 to 2015 Rome 15.120 1715 to 2015 JAMAICA Kingston ZQI 4.700 1630 lo 1830 JAPAN Kure WKLS 6.100 1630 to 2030 Tokyo JLW 7.280 home Service. 0300 Ale to 0900; 1800 to 1800; 2200 to 0230 Tokyo JLG2 9.510 0300 to 0830 THE ARROW FOR KENYA FOLLOW /C Nairobi VQZLO 10.730 0500 to 0600; 0830 to 0915; 0945 to 1100 KOREA AT ITS Seoul JODK 7.0:30 0530 to 0715 TELEVISION BEST! LEBANON Beirut FXE 8.030 0000 to 0115: 0515 to 0800; 1030 to 1600 LUXEMBOURG Luxembourg 6.090 0010 to 0030; 1400 to 1630 15.350 0600 to 0800 MADAGASCAR Tananarive 6.060 1330 to 1400 MALAYA Singapore 4.780 0345 to 1000; 2330 tO T ELE VO IJN 0130 Write for Singapore 6.770 0330 to 1200 Singapore 7.220 1330 to 0130 Free VIEW Singapore 11.730 0325 to 1200 DIRECT Singapore 15.270 0300 to 1200 Brochure Singapore 15.300 0330 to 1200 ASSEMBLY ED. AND MA RT IN au E Port de France 9.700 1780 to 1845; and later PROJECTION MEXICO Guadalajara XEJG 4.820 2200 to 2400 Mexico City XEUW 6.020 0700 to 0100 TELEVISION ASSEMBLIES Mexico City X E UZ 6.130 1500 to 0030 Mexico City XEWW 9.500 0800 to 0200 FOR CUSTOM -BUILT INSTALLATIONS Mexico City XETT 9.550 0700 to 0100 Mexico City XEYU 9.800 eked unknown Mexico City XEQQ 0.680 0700 to 0045 Mexico City X ETW 6.040 0745 to 0045 MOROCCO Rabat CN R3 9.080 0145 to 0500; 1315 to 1900 MOZAMRIOUE Lourenco Marques CR7BU 4.920 1330 to 1600 ; SundaSS, 10110 to 1500 A R RO W ELECTRONICS NETHERLANDS Hilversum PG 6.020 1745 to 2330; Tues-, Y. 0300 to 0430; Wed. 82 CORTLANDT ST., NEW YORK, N. and Bat.. 1030 to 1200; 1600 to 1730 NETHERLAND.nN DI ES Bandoeng 4.790 0730 to 0800 Batavia P M C' 18.130 1100 to 1130 NEW CALEDONIA Station Freq. S le Location Station Freq. Schedule Noumea FK8AA 6.200 0200 to 0400; 0430 tO Location 05110 0030 to 0130; 0145 to NICARAGUA London GRA 17.710 0045 to 0400; 0600 to Paris 11.840 0815; 0915 to 1115 0300; 1915 to 2245; Managua Y N DS 6.760 0800 to 1000; 1700 to 17.730 0830 to 0900; 1700 to 0000 to 0015 2300 London GVQ Managua Y N 0 W 0800 2400 1800; 2345 to 0030 Paris 15.350 0700 to 0900; 1700 to 6.850 to 2015; Managua YNQW 6.910 schedule unknown London GSG 17.790 0545 to 0715; 0830 to 1715; 1915 to 11130; 1100 to 1145 2030 to 2045 NORWAY 0700 to 0900; 1100 to Oslo L K1 9.540 0300 to 0315; 0500 to London G SV 17.810 0030 to 0300; 0400 to Paris 17.7060 1230 0745; 1090 to 1700 11:'.0 NOVA 0100 to 0500; 1100 to FRENCH EQUATORIAL AFRICA SCOTIA London GRQ 18.020 Halifax 2300 19011 Brazzaville FZI 6.1.40 0000 to 01I0; -1100 fo CHNX 6.130 0700 to , 0530 2200 18.080 í0:3o to 1600 2020 Sydney , ,. CJCX 6.010 to London to PALESTINE London -GSMGSM 21.1711 0500 to 1215 Brazzaville FZI 11.970 0445 to 0800; 0930 1030; 1100 to 2020; Jerusalem .. .. JCKW 7.220 2330 to 2000 London GSJ 21.530 0400 to 1215 PANAMA London GST 21.550 0100 to 0400; 1230 to .r 0000 to 0230 Brazzaville F21 15.590 0445 to 0800; 0930 to Colon . HPSK 0.000 0730 to 2300 1500 Panama City 6.030 1800 to 0030 London GRZ 21.690 0800 to 0900; 1030 to - 1030 1600 Brazzaville FZI 17.530 0000 to 0130; 0445 to Panama City HP5H 6.120 0630 to 2400 1230; 1300 to 11.700 0700 0715; 1030 to 0745; 1100 to 1700 Panama City HP5A to 2300 London GYT 21.750 0200 to HP50 2230 1045; 1100 to 1130 FRENCH MOROCCO Panama City 11.780 0630 to London GSK 26.100 0815 to 1200 Rabat CNRS 16.670 0795 to 0830 PERU FINLAND FRENCH WEST AFRICA Lima OAX4Z 5.890 1830 to 2330 Lahti 01X2 9.500 0100 to 0130; 0610 to Dakar FZK6 6.920 1330 to 1700 Lima OAXIV 5.910 1800 to 2400 0740: 1000 to 1000 Dakar F11 E3 11.710 1330 to 1700 PHILIPPINES Lahti 01X5 17.800 0130 to 0200; n500 to GERMANY Manila 11.890 Far East beam. 0400 0545; 0800 to 1700 Munich MUNICH III 0.080 1100 to 1700 to 1005 Stuttgart 6.180 0530 to 0830; 1030 to Manila 15.330 Indlan- Pakintn FRANCE 17:10 beam. 0230 to 0345 Paris 9.550 0000 to 0130; 0715 to Munich MUNICH II 7.150 1100 to 1700 POLAND 0845 Munich MUNICH I 11.870 1100 to 1700 Warsaw 6.100 1100 to 1800 RADIO -ELECTRONICS for Electronics 71 MIDGET ATOM SMASHER An atom smasher no larger than a flower pot detects and counts neutrons, the vital building blocks in the structure of matter, Westinghouse announced last month. The neutron counter was devel- A WI oped jointly by Dr. William E. Shoupp, manager of nuclear physics and elec- tronics at the Westinghouse Research HIGH QUA Laboratories, and Dr. Kuan -Han Sun, INSTRUMENT research physicist. Neutrons cannot be detected by ordi- nary means because they carry no elec- trical charge. They are instrumental, however, in splitting atoms, and Drs. Shoupp and Sun took advantage of this fact, constructing the atom smasher to make them reveal their presence. i 111 pro V /` d ESPEY 511 AM-FM RADIO Here is a fine rádio, in chassis form, to please the most discriminating music lovers. Easy to install in any console cabinet old or new, the Espey 511 AM -FM radio chassis embodies the latest engineering refinements for lasting high quality and enjoyment at a price that defies competition. Dr. Sun with world's smallest atom smasher. Features, 12 tubes plus rectifier and tuning indicator; drift compensated circuit for high frequency stability; In the new instrument a very small tuned RF on AM and FM, high fidelity push -pull audio; amount of uranium 235 is mixed with a special light -producing phosphor and 13 watts power output; wide range 12" PM speaker; the mixture is used to coat the surface smooth flywheel tuning; pFono input provision; of a phototube. The whole device is in separate AM and FM antennas. lined with two inches a metal cylinder Other models available including 25 watt output. of paraffin, which slows down fast -mov- ing neutrons. Write Dept. K for your free catalog. When a neutron passes through the Makers of fine radios 1928. paraffin shield and strikes the uranium - ssince phosphor mixture on the phototube, some of the uranium atoms are split. In the tiny explosion, nuclear fragments MANUFACTURING COMPANY, INC. producing light strike the phosphor, 528 EAST 72nd STREET, NEW YORK 21, N. Y. TEL BUtteleld 8 -2300 rays. The light acts on the phototube cathode and liberates electrons. The neutron -caused explosions can be observed directly on a fluorescent screen, or the electrons can be used to actuate recording devices which give an EASY TO LEARN CODE accurate count of the number of atomic It Is easy to learn or Increase speed explosions. The new detector can count with an Inatructograph Code Teacher. Affords the quickest and most prac- the particles cast off by the exploding tical method yet developed. For be- atoms at the rate of 100,000 a second ginnen or advanced students. Avail- - able tapes from beginner's alphabet 50 times faster than the standard to typical messagn on all subjects. to cut your Speed range 5 to 40 WPM. Always Geiger counter. ready -no ORM. RECORDING COSTS! Though all work so far has been de- ENDORSED BY THOUSANDS! Find out about the MAGNETIC TAPE voted to neutron counting, Dr. Sun be- The Instructograph Code Teacher literally takes the place of an oper- RECORDER that doubles your playing lieves there is no reason the same in- ator- instructor and enables anyone to learn and master code without fur- time, cuts your tape costs in half! Write strument cannot be used to count the ther assistance. Thousands or s operators Pave "acquired the with the nosofuist stem. today for technical literature. heavy mesons -components of cosmic Write today for convenient rental d prcùaseplans. rays -recently discovered in the upper AMPLIFIER CORP. OF AMERICA atmosphere and artificially made in the INSTRUCTOGRAPH COMPANY I giant cyclotron. 4701 Sheridan Rd., Dept. RC, Chicago 40, 398 -10 Broadway, New York 13, N. Y. JANUARY, 1949 72 MINE DETECTOR SCR -625 Brand New ATTENTION; LUMBERMEN, PROSPECTORS, MINERS, PLUMBERS, OIL COMPANIES, etc. * Below is a description of one of the finest metal detecting Mine Detectors ever built. * Operates in the manner of aural and visual method. * If you are looking for metal buried in logs, pipes in the ground, ore bearing rocks, under- ground cables, metallic fragments in scrap materials, metallic money buried or hidden in undetermined places this Mine Detector will probably surpass anything that was ever built. The United States Forestry Service has rec- ommended procedure for using this detector to find concealed metal in tree logs and other timber products. Our government is re- ported to have paid several times the amount of our prices. They originally were sold by War Assets to jobbers for $166.00 * Unit consists of a balance- inductance bridge, a two tube amplifier and a 1000 cycle oscillator. The presence of metal disturbs the bridge balance resulting in a volume change of the 1000 cycle tone. Tubes used are low battery drain types such as I G6 and I M5. The circuit may be modified for control of warning signals, stopping of machinery, etc., when metal is detected. * Operates from two flashlight batteries and 103 v (B). However, a power supply operating for 100 y may be used. * This unit is brand new and comes complete with spare tubes, spare resonator and instruction manual -in wooden chest 81/4 inches x 281/4 inches x 16 inches. Weight in operation is 15 pounds. Packed in original over- seas container. * We do not know exactly what the deepest possible penetration would amount to when this detector is used but we have had customers who have bought the detectors with the expectation that the de- tector would locate metallic objects buried sev- eral feet under the ground or under water and we have absolutely no complaints whatsoever re- the detector not living up to the cus- our price tomertomers'tourers' expectations. is 79 * We "can not overemphasize our belief that an Army surplus detector could solve prob-ppif Shipping lemsyinudefectinglems metal that this detector rshould Weight 125 pounds the bill. NOTE: Batteries are not furnished, we can supply for $4.50 extra. z,deo / Unless Otherwise Stated, All of i ¡` This Equipment Is Sold As Used REQUIRED 41$ 130 W. New York $ 4C St. WITHHALL ORDERS Indianapolis 4, Ind. Orders Shipped F.O.B. Collect RADIO -ELECTRONICS for 73 PRECISION TEST EQUIPMENT (Government Surplus Release) * Here is an instrument that any mechanic that works on automobiles, boats, or airplanes would be proud to own and we offer it at a fraction of its original cost. * The low voltage circuit tester is a self -contained trouble- shooting device for making a complete and rapid check of the generator- battery circuit, includ- ing any current and voltage regulators which may be used. Battery voltage, regulator and cut -out settings, and generator performance can all be easily deter- mined. * This tester is enclosed in a gray heavy-gauge metal box with a strong hinged top that, when opened, is supported by a slide rod and when closed, is latched by clamps. There is a carrying strap attached to the box. * This instrument was manufactured for the Quarter- master's Corps, United States Government Ordnance Department under the most rigid specifications. It is comparable in beauty and dependability to instru- ments made today that sell for many many more dollars than our price. Electric Heat Control Com- switch, voltage selector (3- circuit toggle switch), meter pany, Cleveland, Ohio, or the Heyer Products Corn - polarity switch, utility switch, volt- ammeter scale se- pony, Inc., Belleville, New Jersey manufactured these lector switch, field rheostat, regulator test selector for the Army. Although the unit you receive may be switch, multisection load resistor, is used to control made by either of these companies, it will be prac- all operations and functions of this instrument. The tically identical to the unit made by the other com- master meter reads 0-60 volts and 0 -60 amperes. pany and all are made under Heyer Products One switch box indicator has following ranges: 0 -9 Company's design and according to Government volts and amperes, scale deviation -0 -9 range in specifications. 1 /10th of a volt, 0 -18 in 2 /10th's of a volt, 0 -60 in I volt and ampere division, 0 -9 in .05th of a volt and * This low voltage circuit tester h 11 3/16" wide x ampere. 9 9/16" deep x 71/2" high and con be used on 14 either a 6 volt or 12 volt system. There is a metal * They are brand new. Each weighs approximately chart attached to the lid of each unit which is easily pounds. The price that we quote is oniy made pos- readable while using the instrument. This chart shows sible because of the fact that they are Government settings of all controls and gives operation instruc- surplus and this company bought them at a "steal ". tions to be used in conjunction with the operating Remember, this is truly the finest of instruments and is the manual which is included with the tester. One can we cannot over -emphasize that we believe it quickly determine and correct trouble with this in- best bargain ever offered. strument. There are two battery leads with drive -in connectors (with spikes -lead coated) 8' long; am- meter lead (3 -wire) complete with calibrated shunt, 6' long; voltmeter leads with alligator clip connectors and rubber insulators 8' long, and field rheostat leads with alligator type connectors and rubber insulators S' long. The direct reading meter scale 4" in diameter with color -coded scales, along with the push -button Unless Otherwise Stated, All of This Equipment Is Sold As Used CASH REQUIRED WITH ALL ORDERS Orders Shipped F.O.B. Collect JANUARY, 1949 71 Electronics TINY METEORS HELP RADIO T Millions of tiny meteors entering the NoT earth's atmosphere may be responsible RGEST for our ability to receive radio broad- LA casts from long distances during the bNt.. night, states Dr. A. G. McNish of the National Bureau of Standards. Radio waves, which travel in straight lines, must be reflected back to the earth if they are to be heard at any great distance. Tiny electrified particles in the ionosphere bounce the short waves back to earth. The ions that compose this reflecting layer are produced mainly by the ac- tion of the ultra- violet in sunlight which splits electrons off the atoms and molecules high up in the rarefied air. Just Published! Some of the electrical particles may also be produced by impact of tiny cor- puscles shot off from the sun, others b'y PRACTICAL cosmic rays and by meteors. The lower portion of the ionosphere TELEVISION SERVICING is rich in free electrons during the day, By J. R. Johnson and J. H. Hewitt So we aren't the largest radio and parts 375 pages. 6 x 9, over 230 illustrations due to the action of sunlight, Dr. Mc- distributors in the country. Just the Price only same, Nish pointed out. Directly after sunset $4 we can supply anything and everything M last. you an get a book that really gives you the most of the electrons are gone because low -down on television servicing-one that tells step by needed in the electronic field. And don't step what. to do and also you specifically on pre- they recombine guides you overlook this fact -lower with molecules. cautions to take and the mistakes to be avoided. PRAC- operating "Yet TICAL TELEVISION SERVICING is all the name Ito. expenses mean savings to our customers. -and herein lies the mystery -a piles-a complete. down -to -earth working manual for those sufficient number of who want to understand television servicing fully. get Let us know what you need. We're sure electrons persist at straightened out on the vast mount or 511Sinformation we this lower height all through the night that Is creeping Into the television picture. and really can fill your needs ... and our prices be able to do television servicing work. are always right. Drop us a line and get to reflect radio waves," Dr. McNish NOT a Book of Mere Theory on our mailing list. said. This isn't a book of theory. mathematics and general "Judging from the rate of electron - discussions. The authors -one a radio editor, the other well -known engineer -actually owned and operated a tele- decay just after sunset, one would not vision service shop to get the specific. how- to -do -it infor- ADSON RADIO & ELECTRONICS CO. expect to find any significant number mation they now pass along to you in easily understood form. In addition to a clear explanation of how television 221 Fulton Street New York 7, N.Y. beyond midnight." mponente, construction and operation differ from radio they show exartls how to perform all specific operations in Meteors may be the agency responsi- troubleshooting. diagnosing and remedying television r L ceiver troubles. You don't bother with needless theory. ble for reflecting the radio waves at You are actually shown how to do the work! night. Astronomers estimate that more MAKES TELEVISION REPAIR WORK than a thousand billion of these parti- EASY TO UNDERSTAND TELEVISION KITS cles, smaller than grains of sand, enter Here are the subjects covered: A real buy! A T' television kit with all the fea- the ear'th's atmosphere during a 24- I. Television Is Here 10. Test Equipment and tures of the more expensive sets. 6000 Volt High hour period. Traveling at speeds to 2. Fundamentals of the Alignment Voltage Supply assures clear pictures at all up Television System IL Wiring and Repair times. Comes with factory built, precision -engi- 200,000 miles per hour, they would The Radiofretueney. Techniques neered thirteen channel tuner already aligned. Intermediate -frequency 12. Common Troubles in Uses high -fidelity FM sound. Complete with smash violently into atoms and mole- and Detector SettIons Television Receivers illustrated instruction manual giving assembly cules of the upper air. These meteors 4. Video Amplifiers 13. Treubleshooti ng dato, alignment procedure, service notes and would tear some of the electrons from 5. Cathode Ray Tubes 14. Servicing Hints and much helpful information. 18 tubes for this set Case can be furnished 6. oCirircuitsng and Histories for $39.58, cabinet these particles to which they belong and Srni for $21.00. You can't go wrong at 55950 Synchweep 15. Color Television thus maintain the roof. A. Intermediate Fre- this low price radio 7. Power Supplie, of LESS TUBES quencies of Standard 6. Antennas and Wave Receivers Propagation 8. Receiver Layout 9. Television Receiver 0 lag rams R. F. MASS SPECTROMETER Installation C. Glossary FACTUAL SERVICING DATA ON 10" TELEVISION KITS A new method of tracing chemical flow to lest for an intermittent peaking coil elements in certain parts of the body or transformer For those who want the ultimate in TV kits, this How to get a signal over a mountain la" kit has everything; electromagnetic =con- has been developed. What to do when the linearity of the picture ning and focusing, A.F.C. horizontal hold con- and many fine 17 tubes During radar research it was found is poor trol, other features. for Flow to guy a mast properly this set sell for $57.30, cabinet for that water vapor and oxygen absorbed Checking video a square wave $23.50. Worth many times more $99.50 response with Than ultra- high -frequency radio energy; When to use mica capacitors in place of other LESS rueEa types their presence in air put an upper limit . and scores of other on the frequencies which could be used. practical problems Further research at M.I.T. and Colum- 5 showed 10 DAYS SEND NO MONEY -TUBE RADIO KIT bia University that certain A real buy. Comes complete with other gases and solid elements absorbed TRIAL JUST MAIL COUPON 5" Alnico speaker for only $9e757 waves of particular frequencies. The new spectroscope transmits u.h.f. Write for our new 1948 illustrated catalogue. waves of frequencies in the bands which Dept. RE -19, Murray Hill Books, Inc, 232 Madison Ave.. 16, are absorbed by specific isotopes. Speci- New York N. Y. LAKE RADIO CO. Send me Johnson & Newitt's PRACTICAL TELE- SALES mens of the skin, hair, or nails of ani- VISION SERVICING for 10 days' examination on 615 W. Randolph Street, Chicago 6, III. approval. In 10 days I will send $4, plue a few cents mals which have been fed small quan- postage. or return book postpaid. Postage paid on cash orders; same return privilege. (Rooks sent on tities of the selected isotopes are placed approval In U.S. only. Price outside U.B. $4.50 post- in the path of the r.f. energy. A detec- paid). PEN -OSCIL -LITE records how much the Extremely convenient tion device of \rame test oscillator for all radio servicing:icing: lignaient Small a pen Self powered transmitted energy is received. The dif- Range from 700 cycles audio to over 000 °mega - u.h.f. Output from zero to 125 v Low in Address cyclesost Used by Signal Corps write for information. ference is the amount absorbed by the City. Zone. State GENERAL TEST EQUIPMENT isotopes. From this information, the quantity of the given isotope in the Occupation 38 Argyle Ave. Buffalo 9, N. Y. specimen can be calculated. RADIO -ELECTRONICS for 75 A CHALLENGE -order a model 247. Disregard the unbelievably low price and compare it on the basis of appearance, quality and performance to any other Tube Tester (ANY MAKE, ANY PRICE). If you are not completely satisfied with the model 247 after a 15 day trial, return it to us for refund -no explanation necessary. full The model 247 is not surplus nor is it a hashed over pre -war model. It is newly designed and incorporates new advances in Tube Tester design. Read the description below and order one today! The New Model 247 TUBE TESTER Checks octals, loctals, bantam jr. peanuts, television miniatures, magic eye, hearing aids, thyratrons, the new type H. F. miniatures etc. Features; * A newly designed element selector switch reduces the possibility of obsolescence to an absolute minimum. e When checking Diode, Triode and Pentode sections of multi- purpose tubes, sections can be tested individually. A special isolating circuit allows each section to be tested as if it were in a separate envelope. Model 247 come, complete * The Model 247 provides with new speed - read a super sensitive method of checking for chart. Comes housed in shorts and leakages up to 5 Megohms between any and all of the handsome, hand - rubbed S terminals. oak cabinet sloped for * One of the most important improvements. we believe, is the fact bench use. A slip - on that the 4 position fast-action snap switches are all numbered in portable hinged cover is exact accordance with the standard R.M.A. included for numbering system. outside use. Thus, if the element terminating in pin No. 7 Size 10%" x 8%" 5%". of a tube is under i test, button No. 7 is used for that test. The Model 88 A COMBINATION SIGNAL GENERATOR and SIGNAL TRACER SIGNAL GENERATOR SPECIFICATIONS: SIGNAL TRACER SPECIFICATIONS: 'Frequency range: 150 Kilocycles to 50 Megacycles. The R.F. Signal Frequency 'Uses the new Sylvania 1N34 Germanium crystal Diode which combined with a re- is kept completely constant at all output sistance- capacity levels. Modulation is accomplished network provides a fre- by quency range of 300 cycles to 60 Megacycles. Grid -blocking action which is equally ef- ective for alignment of amplitude and fre- The Model 88 comes complete quency modulation as well as for television with all test leads and operat- receivers. R.F. obtainable eparately or ing instructions. ONLY $2885 modulated by the Audio Ere,. zency. THE NEW MODEL 670 The New Model 770 -An Accurate Pocket -Size SUPER METER VOLT -OHM MILLIAMETER (Sensitivity : 1000 ohms per volt) SUPER METER. A combination Features: VOLT - OHM - MILLIAMMETER plus CAPACITY Compact -measures 31fí" x 61/s" x 2% ". REACTANCE. Uses latest design 2% accurate 1 Mil. INDUCTANCE and DECIBEL D'Arsonval type meter. Same zero ad- MEASUREMENTS. justment hobs for both resistance ranges. D.C. VOLTS: 0 to 7.5/15/73/150/750 / It is not necessary to readjust when 1500/7500. A.C. VOLTS: 0 to 15/30/ switching from one resistance range to 150/300/1500/3000 Volts. O U T P U T VOLTS: 0 to 15/30/150/300/1500 /3000. another. This is an important timesav- D.C. CURRENT: 0 to 1.5/15/150 ma.: ing feature never before included in a 0 to 1.5 Amps.RESISTANCE: 0 to 500/ V.O.M. in this price range. Housed in 100.000 ohms. 0 to 10 Megohms. CA- round- cornered, molded case. Beautiful PACITY: .001 to .2 5l(d-. .1 to 4 Med. black etched panel. Depressed letters (Quality test for elertrolYtles.1 REACT- ANCE: 700 to 27.000 Ohms: 13.000 Ohms filled with permanent white, insures Ns, to 3 Megohms. life even with constant use. Specifications: 6 A.C. VOLTAGE RANGES: INDUCTANCE: 1.75 to 70 Henries: 35 0- to 15/30/150/300/1500 /3000 volts. n.11llo lieu ries. 6 D.C. VOLTAGE RANGES: 0- 734/15/75/ DECIBLES: -10 to +18. +10 to +38. 150/750/1500 volts . +30 to -¡-58. 4 D.C. CURRENT RANGES: 0- 134/15/15n Ifa. 0 -1% Amps. The model 670 comes housed a in rugged, 2 RESISTANCE RANGES: 0 -500 ohms. 0 -1 steel cab- inetlead completem ouste with test The Model comes complete lards and operating in- 770 $1390 structions. Size with eads n rod batteries. 5%' x NET test loos and all operating NET 7r," z 3'. instructions. Available for Immediate Shipment From Stock -20% Deposit Required on All C.O.D. Orders DEPT. ST. MOSS ELECTRONIC DISTRIBUTING CO. 7. N Y JANUARY, 1949 76j Try This One PANEL LETTERING Designations can easily be printed on radio panels with a rubber stamp out- BUILD THE NEW fit, obtainable at most stationery stores. The choice of stamp pad ink is impor- MODEL TV -67 ALL CHANNEL tant. Volger's opaque ink, available in several colors, and special stamp pad are excellent for marking dark panels; mistakes can be wiped off with a rag moistened with benzene. HAROLD PALLATZ, TELEVISION BOOSTER Brooklyn, N. Y. FOR YOUR OWN USE OR FOR RESALE CONDENSER GROUND LEADS Many of the new molded tubular ca- With the aid of our TV -67 pacitors have no mark to indicate which INDUCTOR TUNER lead is connected to the outer foil. To Illustrated below. determine which is which, connect the capacitor across the input of an audio $350 amplifier and place your finger on the only capacitor at the end from which the grounded lead emerges. Then reverse INDUCTOR TUNER comes com- the capacitor connections and repeat plete with circuit and instruc- tions for building the TV -67 the test. TELEVISION BOOSTER. When your finger induces the least We will also include at no charge is basic circuits utilizing the TV -67 hum, the grounded lead the one con- INDUCTOR TUNER to build a nected to the foil. Television and F.M. Signal Gen- ALAN SMITH, erator, a Television Interference Eliminator and front end for Shaftesbury, Vt. Television Receiver. USE FOR SOCKET PUNCHES Many people do not know that screw - No need for switching when type tube -socket punches (such as the using the TV -67 Greenlee and others) will also work with Presdwood, Bakelite, and hard rubber. NORRIS MCKAMEY, INDUCTOR Davenport, Iowa TUNER CLEANING TOOL Designed to Cover All Chan- Here is an interesting and useful tool nels 2 to 13 Inclusive. which makes cleaning inaccessible parts, such as band switches and variable capacitors, much easier. Remove the head from an old vibrator -type electric TV -67 Booster Features: shaver and attach a short fiber stick to * Permits use of Indoor Installations. the vibrating driver. The fiber is at * Reduces or eliminates interference including Amateur, F.M., Short Wave and Inter- right angles to the shaver so that when Channel. the shaver motor is turned on it vibrates cotton is to Permits TV reception in fringe areas. lengthwise. A piece of glued * the other end of the fiber stick. * Amplifies weak signals. To use the gadget, dip the cotton in * Provides brighter and clearer images. carbon tetrachloride, start the shaver, and apply the cotton to the dirty part. Specifications: The vibration will make the cotton wipe off the dirt. The Model TV -67 employs 1 -6AK5 as a high gain amplifier; 1 -6C4 as an isolation * LLOYD O. WALTER, amplifier and 1 -6C4 as rectifier. Use of these highly efficient miniature tubes in con- junction with INDUCTOR TUNER results in maximum gain on all channels up to Dillonvale, Ohio channel 13. DIAL POINTERS * The Model TV -67 provides a 6 megacycle band -width reducing Video detail loss to absolute minimum. To make a new pointer for a dial which lost its original one, straight- * The Model TV -67 is designed to operate with any antenna system indoor or outdoor - has any impedance. en a 12 -inch length of solid tinned cop- per wire by fastening one end of it to * New INDUCTOR TUNER covers all television channels, 2 to 13, inclusive without switching. a nail or screw on the bench and pulling on the other end with pliers until it INDUCTOR TUNER comes complete with circuit breaks. Cut a piece the needed length, and instructions for building the TV -67 Television and fasten it to the dial shaft. Booster. We will also include basic circuits utilizing This is an excellent way to straighten the TV -67 INDUCTOR TUNER to build a Television wire for any purpose. and F.M. Signal Generator, a Television Interference GEORGE L. GARVIN, Eliminator and front end for Television Receiver. only South Bend, Ind. BC RECEPTION Some surplus receivers, such as the GENERAL ELECTRONIC DISTRIBUTING CO. BC -348, can be converted to broadcast - band reeeption with the aid of an a.c.- 98 PARK PLACE NEW YORK 7, N. Y. DEPT. RC -1 d.c. midget broadcast set to whose i.f. the surplus unit can be tuned. RADIO -ELECTRONICS for 77 INSTRUCTION MANUALS GREAT TUBE VALUES DC 312. BC 342 11.25 SCR 281... 91.25 SCR 509 1.25 DYNAMOTORS 01-A 5.45 12A6 .35 860 15.00 Mark 11 1.00 SX -32 1.00 1524 .S5 1388V .65 561 40.00 2C21 .69 12557 .9 874 1.95 2C22 .69 11557 .72 876 4.95 2J21-A 25.00 15R 1.40 1005 .35 VIBRATORS 2.122 25.00 2507 .75 1613 .95 2.126 25.00 30 (Spec.) .70 1619 .21 TR 1210. 12 vole. 5 pin 91.00 2J27 25.00 45 (Spec. .59 1624 OAK V -6075, 24.32 vde, 7 pin 1.00 2J31 25.00 39/44 .49 1629 .35 Mal. Type 534C. 12 vde. 5 pin 1.00 2132 25.00 35.51 .72 1961 5.00 Mai. Type G029a. 12 vde. 4 pin 1.00 6.0111 3.136 25.00 2278 3.85 9002 .65 Radiaart 82. v. DC. 6.pin specil 1.00 Input 2J39 25.00 225 8.80 9004 .7 - Mfrs. quantitlea available. Type Volts Amps Volts Ampso Rst Prim 2J55 25.00 265-8 20.00 .7 S D 778M 14 40 1000 BC 191 520.00 N 3J31 55.00 355A 19.50 CE072 1.95 14.00 LN 21(2/879 4178 E 73 28 10 1000 .330 BC 375 24.50 N .69 25.00 E F 50 XMTR TUNING UNITS DM 21 14 3.3 235 .090 BC 312 3.5 LN 3A4 .85 530 90.00 E-1145 .75 DM 2168 28 1.6 235 .090 BC 312 N 35111 2.25 531 45.00 i-127 20.00 For BC 610: TU 48 -3 : 47 3.5 12.5 TU DM 25 12 2.3 250 BC 307 3C24 .80 532 3.95 F11255* 165.00 Iß.9 Inc); TU 53 (8.12 me). Each 11.75 .050 2.49 I.N 3C30 .70 559 .00 FC 271 40.00 For BC 17 me): TU 18 DM 28R 28 1.25 275 .070 BC 348 8.75 N 223AX: TV (2.3 DM 33 28 7 840 .250 BC 5.50 N 3116 79 582 90.00 OL 562 75.00 -4.5 . Each 91.95 450 3C1 3.50 615 .89 CL 623 75.00 DC 3O0.Á. Antenna DM 42 14 48 513 .110 SCR 500 0.50 LN Loading unit for BC 10//30 .050 3021.8 1.50 703-8 7.00 01 897 75.00 375 & BCC IDI ...... 52.75 3011 2.25 704-A .75 ML 100 60.00 D-104 12 326 .100 14.95 N 3E11 2.95 705-A 2.55 13859 65.00 Ó0Óvde. originally used for Collins ART-13 .200 3F17 3.55 707- (20.00 O 860 65.00 xmtr S .69 DA-3A 28 10 3000 .280 SCR 522 8.95 N 3611 3.50 25.00 0891 65.00 150 .010 305 .79 715-5 12.00 Q882 65.an 14.5 S9r1 1.20 7205V 50.00 PICO 932. .65 ROTARY BEAM CONTACTOR :5053 28 1.4 250 .0130 APN -1 3.05 N 55P4 4.95 721-8 3.60 VP 91 l.On 1100 .400 TA -2J 15.00 N 5CP1 3.75 713-A/S 12.50 VE 130 1.25 ASSEMBLY % E SS ?.J7 25 500 .400 SCR 245 5.25 LN 5FP7 3.50 72411 1.75 VR 135 1.25 fm.vm FE 86 28 1.25 250 .060 RC 30 N SJP2 .00 725.1 25.00 VR 137 1.25 dulyooLrlow-loss' PE 101 C 5J30 726-A 15.00 120 1.00 dla form rwith bear.. 13/26 12.6/ 00 SCR 515 5.25 39.50 vu Mg to 8t 13I..odism.. shaft. Anwexcellent 0.3 800 .135 60 2.00 600 2.25 Vu 134 1.00 feeding AC 1.12 6L60A 1.00 50l-A 1.10 WL532 4.75 unit for that new beam. Each ring 0 89 93 28 3.25 975 4.95 N 65C7 .70 504 9.95 WS ISO 3.nn Is brought out to a separate pin. New 23350 27 1.75 3.50 7C4 1.00 e1S 2.50 99.45 ea. 285 .075 N WT 280 5.00 35X0455 28 1.2 250 .000 3.50 N 7E5 1.00 536 1.15 Cavity. ZA.0515 12/24 4/2 500 3.95 N 7E6 .72 537 1.95 t With 5-19 pack 12 9.4 275 .101O Mark II 101' .60 843 .59 Photocell. INVERTERS .050 9.95 N N-New. LN-Like NéwO Le,.. Filter Box 6 Relays PE 218:Input: 25 -28 VDC @ 92 amps. Output; 115 rolls Cir 1500 volt-amps. 380-500 cycle.. New. Berm. Sealed CROSS POINTER (as shown) .249.95 Coed. Ex. Cond.S35.00 INDICATOR CARBON PILE PE 200 -A Input: 28 Dual 0 -200 mlroamp. movement In 3" VDC IN 38 amp. Out- case. Nadi movement brought out to 6- VOLTAGE put: 80 volta 6 500 term reeeptable at rear. Originally used volt-amps. 800 cl'clMI. in T1.5 equipment. New $5.50 Leland. New, complete REGULATORS ith enclosed relay 161911 1619!! 1619!! filter, instructi Type 16111 vacuum tubes, fl2 octal based pentode. . . The 50 most versatile high perveance tube at A New lo price. 5.21 ea. 5 for...... 51.00 Type TYPICAL CHARACTERISTICS "A ": Coll current .105 to .115 HEADSETS Filament 2.5 °v Amps amps. 80 volts. Leland Electric.. 53.00 A Class C RF Amp (Talon.) Class 552 Audio (2 Tubes PP) Dynamic mike and headset combination. high Plate Vola 400 400 Type "C" Input: 22 -30 v. colt, 30 quality, efficient unit, used in B -19 tank Xmtre. Screen Voltage 300 300 amps. Mike and phones complete, new $2.75 Plate Current 75 ma 75/150 ma Output: 19 v. 5.7 amps. Spec. Screen Current 10.5 ma R -15 headsets: 8000 ohms impedance, nlbber Grid Voltaire -55 0.5/11.5 ma c VR9000 -2e. Leland Electric laa ions. Comes with 8 cord and PL cushions. ft. plug Grid Current shown) 53.00 55. Grid Drive .30 W a HEADBANDS: -1, ITB -4. DB -30. New .25 ea. Output 10.5 W s35X045B: 22 v. .1 to 3 amps. for nB While ey last s 21 en. or 5 for 51.00 K -14B Ounsight. Webster 53.00 SCR 11.10 METER PORTABLE 610 I All merchandise Mail orders promptly filled. 131-C F.O.B. cok City. MOBILE RIO Moneyne Order or Cheek. Only shipping chargesese .O.D. SCR 610 portable transmitter- receiver. 27 en PHONE 38.9 me crystal controlled, using FM for effici- Liberty St. ent operation. Unit consists of Xmtr -rcvr BC I DIGBY 659 and power supply PE 97 ... operating from COMMUNICATIONS 6 or 12 vdc. Slightly used, excellent condition New York 7, N.Y. EQUIPMENT CO. Less xtale 525.00 MANUFACTURERS QUANTITIES AVAILABLE 9 -4124 Disconnect the secondary of the last i.f. transformer from the remainder of the broadcast -set circuit and attach leads of convenient length. Connect AT LAST!! A LOW COST POWER these leads to the antenna and ground posts of the surplus receiver. Now tune the surplus receiver to the i.f. of the midget, and tune the midget for which- UNIT FOR SERVICE WORK ever station is desired. This is a particularly valuable idea 44AH when the surplus receiver has a good ELIMINATOR KIT audio end. The broadcast -band receiver from a 274 -N, for example, was used to #KC 1 -10 feed the input of a BC -779 -B in one Including pic- setup. torial and only schematic CURTIS M. EGGERS, $1950 diagrams Las Vegas, Nev. USING KNIFE SWITCHES For the first time, we are offering a well- engineered six volt direct current power unit for auto -radio and similar service work in kit form!! In many applications requiring a This unit was formerly in the high priced range. Now, we have placed all the essential single -throw knife switch, it is better to 'components necessary for construction in kit form, and are offering them to you at this low, use a double -throw unit. The double - low price. a off throw switch has positive position, These kits fulfill the long -standing need of every serviceman and technician. They are keeping the blade in place so that the designed to operate from a z15 V.A.C. 5o /6o cycle source, and deliver 6 V.D.C. well -filtered circuit is less likely to be closed acci- from three to eight amperes, with a peak rating of ten amperes. The A.C. ripple percentage is dentally. held to remarkably low values. CHARLES ERWIN COHN, This unit charges a standard auto battery in one day!! Chicago, Ill. Do away with bulky batteries! Do away with corroding fumes! WIRE STRIPPER Simplify your service operation! A pair of pocket fingernail clippers Order this line kit for your bench today!! can be used as a wire stripper. Clamp No C.O.D.'s. Full remittance with order. Shipping wt., 12 lbs. the wire in the jaws and pull. If the ATTENTION DEALERS! Write for quantity dtMcouut5 pointed end of the depresser is filed off, it can be used as a small screwdriver. OPAD -GREEN COMPANY CECIL HARRISON, 71 Warren St. Phone: Spencer, Okla. BEekman 3 -7385 New York 7', N. Y. JANUARY. 1949 s I 1llicsti011 INSTRUCTIONAL RECEIVER PHONO AMPLIFIER am- eel I would like to have a diagram of inquiries are answered Please design a phonograph Questions Box a volt- a one -tube radio to which a second by mail. Those of general interest are plifier using a pair of 35Z4's as (audio) stage can be added at some printed on this page. A fee of $7.00 age doubler, a 35L6 as output tube, and future time. The set is to be used for is charged for questions requiring no a suitable 12 -volt tube as voltage am- instructing students in the elements of research or schematics. Write for esti- plifier. Provide a microphone input, too, radio. -G.E.J., Bedford Hills, N. Y. mates on questions requiring research please.- L.I.M., Milwaukee, Wis. or schematics. Be sure to give full specifications and details. Due to you asked for is A. The set you requested is shown in it A. The amplifier nominal fees charged for this work, you use a the diagram. The r.f. tube is the 1S5. must be handled as o part -time prop- shown in the diagram. If When the 1S5 circuit is constructed, osition. Therefore rapid service is im. PICKUP OR MIKE 125J7 35L6 T use the headphones in the position possible. Six to eight weeks is re- XTAL CS shown by the dotted lines in the dia- quired to draw up answers involving gram. When ready to build the 1S4 large drawings or research. amplifier, connect the 1S4 grid in place of the phones, and use the phones at 70 ANT POST the output of the 1S4. 6L7 The receiver will have fairly low gain. To increase the gain, the 1S5 is made regenerative. Over a standard broadcast loop antenna wind 10 to 15 turns of No. 28 wire. You will have the 2/elS4 L 3 R3 B+ NI OAP PHONES A+ TO ADO 1S4 CONNECT HERE c 117VAC 35Z4 2 ) C2 C4 1 RI- 500,000-ohm potentiometer R2 -560 ohms /2 watt R3-4.7 mego(tms, V2 watt R4- 100,000 ohms, 1/2 watt R5-470,000 ohms, '/2 watt R6- 15,000 ohms, I/2 watt I watt -L- R7-150 ohms. 1 R8-3,000 ohms, 10 watts R9-270,000 ohms, y7 watt CI -10-0 25 -volt electrolytic + -IF-+ 270,000 ohms, y2 watt RI- C2- .05 -µ1, 400 -volt paper 1/2 watt A+5 8 +45-90V R2, R6- 47,000 ohms, C3 -8 -0, 450 -volt electrolytic ohms, 1/2 watt R3-470 C4- .0I -uf, 400 -volt paper 22,000 ohms, 1/2 watt RI, R3-2.2 megohms 1/2 watt R4- CS- .025 -0, 400 -volt paper ohms, 2 watts R2-I megohm, i/ watt R5- 15,000 C6- 20 -uf, 450 -volt electrolytic R7 -3,300 ohms, 1/2 watt CI- 365-fµµ variable Cl. C8- 20-0, I50 -volt electrolytic .02 450 paper C2- 140 -µ0 variable CI- -0, -volt C9-0.25 -1f, 400 -volt paper C2, C7 -gang, 365 per -gang, air variable C3 -250-µµ10 mica -2 -40- T- output transformer, 5,000 ohms to voice coil C3, C4-0.5 450 -volt C4- .01 -0, 150 -volt paper -0, paper SPKR-PM speaker Broadcast loop antenna (see text) C5- 0.1 -uf, 450 -volt paper A-1.5-volt battery C6- .001 -0 adjustable padder microphone, you may not get as much B-45- to 90 -volt battery C8-100 -µµf mca SW- s.p.s.t. toggle switch LI- broadcast antenna coil (Miller A -727 -A or volume as you want unless a high -out- equivalent) put crystal is used. In any case, the both L2- broadcast oscillator colt (Miller B -727 -B or correct number of turns when equivalent) output will be higher from a crystal volume and regeneration are easily con- T-i.f. transformer, 1500 -kc (Miller 912 -WI or phonograph pickup. trolled by C2. equivalent) If B is 90 volts, you may replace BAND -SWITCHING RECEIVER the headphones with a suitable output I am building a short -wave set COIL TABLE transformer and PM speaker. ? Band Coils Wire Turns Length Tap CI with band switching. Please give me (AW6) (µf ) specifications for coils for 6, 10, 20, and 75 meters LI, L3 28 13 close -wound CONVERTER FOR BC -312 (4 mc) L2, 14 28 53 I inch 75 meters.-B.R.S., Vine Grove, Ky. LS 28 39 I inch 14 .006 ? Please print a diagram for a broad- 20 meters LI, 13 22 6 close -wound cast -band converter to be operated with (IS mc) L2, L4 22 11 1/2 inch A. The front end of a typical receiver LS 22 10 /2 inch 3 none receiver.-E.W.W., L3 22 5 a BC -312 surplus is shown in the diagram and coil data 10 meters LI, close -wound Jefferson, Ohio. (30 mc) L2, L4 22 51/2 l/s inch is given in the table. To get perfect LS 22 51/4 / inch 2 none tracking and the desired coverage it 6 meters LI, L3 14 3 close -wound A. A two -tube converter is shown in (50 mc) L2, L4 14 3 5/16 inch may be necessary to vary the coils LS 14 3 5/16 inch lye none The two filaments should LI between L3 and the diagram. slightly. Spacing between and U and be connected in series to the 12 -volt L4 is about 1/16 inch to V. inch; vary for best re- The coil values have been calculated sults. All coils wound on 2/4 -inch- diameter forms. All winding of the transformer in the BC- wire enameled. Tap column shows number of turns 312. B- voltage and a.v.c. can be obtained for an i.f. of 1500 kc. up from ground end. from the receiver as well. SC B+ T 6SA7 The tuning range of the converter is ua[R about 550 -1500 kc. If you have a local station at 1500 kc, you will be unable :l R2 B+ to receive it unless you set the i.f. coil to about 1560 kc, connect a signal 0 Tcn generator set to 1560 kc to the 6L7 ( _ osc' grid cap, and tune the transformer for MC ' SC + AVC S 6J5 output. maximum receiver 3 GANG-25$0 PER SECTION - IF 1500KC To use the converter, connect its out- to post of the BC -312, put the antenna RI -47,000 ohms, VI watt C4 C7-.05-0, 600 -volt paper tune the receiver to 1600 (or 1560) kc, R2-55,000 to 10,000 ohms, /2 watt CI11-I00 -40 mica Cl-see coil table C11 -0.1 -0 600 -volt papar and tune in your station with the con- ) C2, C. C9-3- 30-140 mica trimmer T- 1500 -kc f. transformer verter. C3, CS, C$-25 -µµf, 3 -gang tuning capacitor LI, 12, 1.3, L4, 15-see table RADIO -ELECTRONICS for People 79 Dr. Willard H. Bennett has been des- ignated head of the Physical Electronics Section of the Atomic and Molecular Physics Division, National Bureau of Standards, where he will be actively en gaged in basic research on cathode emission processes and the physical properties of negative atomic ions. Dr. Bennett is responsible for the recently developed radio - frequency mass spectrometer tube and assisted in the a early development of a gas -filled, cold - cathode rectifier. He has also done considerable re- search on high - voltage generators BRATION and tubes and nu- merous other electronic devices. opoo Ricardo Muniz of Rutherford, N. J., well known to readers of Gernsback publications as the author of articles on technical subjects, has been appoint- `HEAT ed to the post of General Manager of the Television Receiver Division of Allen B. Du- Mont Laboratories, Inc., of Passaic and Clifton, N. J., according to Leon- ard F. Cramer, Vice President of e the company. George D. O'Neill, assistant to the manager of research, Sylvania Electric Products, Inc., Flushing, N. Y., has been elected Fellow by the Board of Directors of the Institute of Radio En- gineers. He will receive a Fellowship Award for his work in electron -tube theory and design during the Institute's National Convention in March, 1949. SPRAGUE TUBULAR CAPACITORS Among his engineering contributions widely used in radio and electronic de- velopments are: Types and twin - element TM MB tubes; indirectly (600 Volts) (1600 Volts) heated power out- put tubes; indi- Take a look at Sprague Type TM and MB Phenolic Molded rectly heated, low - Tubular Capacitors! See how their sturdy phenolic jackets offer voltage -drop recti- complete protection against moisture, vibration and heat -the fiers; and micro- three factors that cause 9 out of 10 failures in ordinary wax tubu- wave developments lars. Then try Sprague TM's and MB's on your toughest jobs -and restricted for se -. curity reasons. you'll quickly understand why-these little -units represent the During his career greatest capacitor development in modern radio servicing history! as a radio engi- Sprague TM's and MB's are a "must" for auto radio, aircraft neer, he has been granted twenty pat- ents and now has six applications pend- radio and television applications. And because they cost exactly ing. the same as ordinary wax cardboard tubulars, wise servicemen use them exclusively for all service replacements. no Milton L. Kuder, prominent in Navy There are radar anxl guided missile development service complaints, no dissatisfied customers when you projects, has been appointed to the staff use Sprague TM's and MB's. of the National Bureau of Standards, Get the genuine article! Be sure and ask for Sprague Mr. Kuder will be concerned with re- search and engineering in the Bureau's TM's and MB's by name! Ordnance Research Section. Dr. Allen V. Austin has been named Chief of the Electronics Division, Na- SPRAGUE PRODUCTS COMPANY tional Bureau of Standards, Washing- North Adams Massachusetts ton, D. C., to succeed the late Harry JOBBING DISTRIBUTING ORGANIZATION FOR PRODUCTS OF THE SPRAGUE ELECTRIC COMPANY Diamond. JANUARY, 1949 801 People Charles Freshman, Chicago -born pio- Headphone BARGAINS neer radio manufacturer, died October 2 at his Pasadena, Calif., home. The Type H$23- -8000- ohm i ped- founder of the Charles Freshman Com- once, highly sensitive ... light - ALL IN v/eight only 9 oz. Leather cov- pany, a radio manufacturing company ered spring steel adjustable headband. 12" cord with PL54 in New York in the early 1920's, he plug attached at side out of Masterpiece. woy. lock and rubber cord sup- introduced the Freshman _. plied to extend length to 51/2 the first low -cost, feet. Removable rubber ear TUBE TESTER cushions. Brand New-513,50 mass - produced ra- Value. Stk. No. 17A37 dio for home use. SET TESTER SPECIAL PER PAIR... $2 ,455 Later he set up Type 84530-8000 ohm impedance. Small plants in Chicago BATTERY TESTER " yet highly sensitive. Built on hearing aid principle with ear fitting soft rubber and other cities. In cushions attached to receivers . . shut CONDENSER TESTER ®o. out outside noise. Comfortable, light. 1928 he sold out his metal band easily shapes to contour of in firm AUDIO R.F. - F.M. ,1011 head. Supplied complete as illustrated interest the with 6 foot cord and PL55 plug, shirt for and was Eastern SIGNAL GENERATOR - clip and matching transformer 8000 ohm impedance. Very popular for con- sales director for version to mikes, telephone sets, minia- ture cr9stal sets and all around head - the Belmont Radio RCP Model 8573 phone at the record smashing price only use. Brand New., A Terrific Value! Corporation of n Me. 17A410X, $1 Every square inch solid -backed M Per Pair .29 Chicago before his retirement. with value! Look what you get in V this phenomenally low- priced tester: 5BP4 CATHODE RAY TUBE $2.95 (I) A complete tube tester with over 800 listings in has been ap- (2) A battery tester Has 5" white screen. Quality make individually boxed Dr. Robert D. Huntoon its famous Rollindex roll chart, carton. Brand New, Perfect, Guaranteed. indicating actual voltage under rated load, (3) A in cushioned pointed Chief of the Atomic and Mol- AM. capacitor tester, (4) A fixed point calibrated 5ECIALSPECIALAL EAACH._._._...... _. _.. $2.95 ecular Physics Division, National Bu- FM signal generator, (5) An audio oscillator; and a dozen additional features. ORDER NOW from this ad- include postage. reau of Standards, Washington, D. C. Readable scale divisions on the ohm meter start at He will also serve as consultant to sev- 0.05 ohm to 25 megohms. FREE -the big NEW B -A Catalog No. 491. 132 pages of if you hove not received it. eral specialized laboratories of the Bu- DC Volts: 0, 2.5, 10, 50, 250, 1000, 5000 Ovhtanding Values. Write AC Volts: 0, 10, 50, 250, 1000, 5000 reau's Electronics Division. DC Milliamps: 0, .5, 2.5, 10, 50, 250, 1000 0, 10 DC Amps: BURSTEN-APPLBEY Ohms: 0, 250, 2500, 25000 ' :., Arnold Everett Bowen, research en- Megohms: 0, 2.5, 25 1012 -14 gineer of the Bell Telephone Labora- Decibels: -B to +15, 15 to 29, 29 to 49, 32 to S5 KANSAS CITY 6. MISSOURI Output Voltmeter: 0, 10. 50, 250, 1000, 5000 tories, died at the age of 47 in Strouds- Complete with tubes, batteries and test leads, out- burg, Pa., after a brief illness. Mr. put leads, etc., housed in natural finish oak case; TS-10 SOUND POWERED Bowen helped to develop the system for hammertone gray panel. See this outstanding buy at today write for new catalogue I C. HANDSETS microwaves through hol- your jobber -or These are what .a( have been wait- transmitting RCP INSTRUMENTS --BEST FOR EVERY TEST ing for: Ali. BRAND NlAV. Made low new by we:. RCA atid Automatic Elect. guides, which made possible Requires no batteries transform- ers. Useful rf forms of radar RADIO CITY PRODUCTS CO., INC. tenna installations. inlercomms. line communication. etc. No battery used in World War feature makes It possible to (provide communications in pants where ex- II. During the war, 152 West 25th St. `) New York 1, N. Y. bive chemicals used. Clip u TS -IO on each end of a line d he in bave your communication in a Jiffy. served Wash- Air -mail or wire your aumlity is ington as officer -in- per pair 16.95 of the Air COMPLETE TELEPHONE SYSTEM! charge 2 -13 Handsets. 2- 115152 Telephone -FREE Consists of -TS All Forces' Airborne and duplex copper telephone NEW per set Radar Equipment ILLUSTRATED RM -53 REMOTE CONTROL BOX Two way telephone conversation can be mused over Board with the a transmuter and receiver output Itransftmred to a telephone line with this bandy remote trol box. 1949 CATALOG Talk over transmitter via telephone..ONLY 52.50 en. rank of lieutenant (Send 25 Deposit On All Orders. Balance COD) colonel. Radio and Electronic OFFENBACH & REIMUS CO. Of 372 511(5 Street San ranciseo 2. Calls. Tubes and Parts Dr. Newbern Smith has been appoint- Send For It Today to the Great ed Chief of the Central Radio Propaga- Come Laboratory of the National Bureau All brand new merchandise sell- tion SHOPS OF of Standards, Washington, D. C., where ing retail at wholesale prices - he will plan and direct basic theoretical catering to Hams, Experimen- and experimental radio wave propaga- ters, Servicemen, and Students. COYNE tion research, head the operation of the A new company dealing world -wide net- radio work of radio prop- only in mail orders to give you ÉeRA DIO- agation observa- quicker service on all orders tories, and direct large or small. TELEVISION development of ra- MAIL ORDERS dio measurement RADIO SERVICE standards at fre- NY 75 BARCLAY ST., DEPT. RE, NY 7, PRACTICAL SHOP TRAINING - quencies from 10 NOT HOME STUDY kilocycles per sec- Trained Radio men needed now. Get Radio -Tel- ond to 300,000 evision training and be ready for a real future. Learn on actual equipment at Coyne.50th megacycles per WE ARE Anniversary Year. Not "Home Stud) ". Free second. employment service to graduates. Many earn while learning. If you are short of money, ask been LOOKING about Student Finance Plan. G.I. Approved. G. Lester Jones has appointed Coupon brings special plan for men of dratt age. Chief Engineer of Lear, Incorporated, SEND COUPON FOR FREE BOOK of Grand Rapids, Mich., according to FOR TUBES' an announcement made by Mr. Richard B. W. COOKE. President WHAT HAVE YOU GOT? COYNE ELECTRICAL !t RADIO SCHOOL M. Mock, President of Lear, Inc. Interested in small or large quantities of all 500 S. Pauline St.. Dept. 19 -BU. Chicago 12, III. During the past year, MI-. Jones types Industrial, and Receiv- Send Big Free Radio-Television Book. also your epe- of Transmitting. cial plan for men of draft age. served as assistant to the President of ing Tubes. Send offerings to: Indian Motorcycle, Springfield, Mass., T. L. BLACK, WHOLESALE TUBE DIV. NAME where he supervised subcontracting and NIAGARA RADIO SUPPLY CORP. ADDRESS tooling of two new motorcycles. Mr. Jones was instrumental in setting up 160 Greenwich St., New York 6, N. Y. CITY STATr their new plant in East Springfield. moa RADIO- ELECTRONICS for -New Patents 81 CIRCUIT- DESIGN AID Patent No. 2,446,993 * BRAND NEW! JUST RECEIVED! * Joseph Alter, Long Branch, N. J. * SUPER- SENSITIVE THE NEW SPELLMAN * This device is intended to save time in design- F1.9 PROJECTION TV LENS ing r.f. and a.f. amplifiers. It aids the designer * TELEVISION SET! in selecting optimum values for the components. DESIGNED FOR All the components that might be used in a REMOTE standard voltage- or power -amplifier circuit (the "FRINGE AREA" OPERATION * drawing shows an audio voltage amplifier) are * mounted on a panel, with several different types * AF VOLTMETER 1 * * INPUT LOAD¡ * * Dimensions: Length 1 ", Diameter 41/4" * F1.9 EF.5 in. (127.0 mm.) This lens in- corporates in barrel a corrective lens for * use with a 5TP4 projection tube. It is R GULATED A 34 tube TV set with remarkable gain easily removable for use with flat type * POWER and hold characteristics. Set contains 10" tubes. Lens can be utilized SUPPLY to project pic- picture tube. A natural for "fringe area" ture sixes from several inches to 7x9 feet. * dealers who must supply their customers complete with mount- with good television reception. AVAIL- Only ing ring. of tube sockets wired in parallel. $90 * All components ABLE FOR IMMEDIATE DELIVERY. are made variable to eliminate the necessity for Machined slotted Mounting Ring avail- soldering in a number of different capacitors Write for technical able for hand focusing adjustment. Has * or resistors. complete data and further in- 4 holes for easy mounting on plate. Indicating lights are placed above the controle $469 formation. $8.00 extra. * to indicate which ones are in use. SEND FOR FREE PROJECTION T_LEVISION CATALOG STP4 Projection Kinescope Tube Stand for Projection Television Soft * 30 KV RF Power Supply Front and Rear Projection Television SUPERSONIC INSPECTION Projection Television Chassis Screens Patent No. 2,448,398 Hi- Voltage Coils Hi-Voltage9 RF Coils-151(V, 251(V, 30KV Hi- Voltage Television Voltage Vincent G. Shaw, Pittsburgh, Pa. Capacitors Hi- Meter-0 to 30KV Include 25% Deposit With Order, Balance C.O.D. * (Assigned to Sperry Products, Inc.) The thickness of an object, or the distance from PIONEERS IN PROJECTION TELEVISION its surface to a flaw beneath it, is measure: by the time needed for supersonic waves to travel TELEVISION through it. As in radar, the time between a trans- SPELLMAN CO., INC. mitted pulse and its reflection (from the flaw or DEPT. f3 , 130 WEST 24th STREET, NEW YORK 11, N. Y. AI. 5 - 3 6 8 0 the other surface of the body) is observed on a cathode -ray tube. REFLECTED PULSES %MITTED PULSE AC POWER SUPPLY AND SPEAKER DYNAMOTORS Completely wired power supply INPUT OUTPUT STOCK NO. PRIG' and speaker. volume with con- 9 V. DC 905 V. 95 MA DM 635 X 83.0 - trol l' W and on C o:f (twitch. housed In a metal cabinet. size 12 V. DC 220 V. 100 NIA D 402 3.93 4 (i," a í't4' s 4!5'. For receiver 12 V. DC 940 V. 200 MA D 401 7.93 showy) below or any other type V. command receiver: ready to plug 12 DC F/ SCR 522 PE 98 i"-.93 into receiver or rack. and 110 18 V. DC F/ SCR 522 PE 94 7.95 Volt 60 cycle line. 12/24 V. DC F/ No. 19 MARK II P/S #3 9.50 V Wired t"nk 13/26 V. DC F/ BC 695 l'E 101 2.93 Price-Kit of l'arts $9.975 28 V. DC 400 Cycle Inverter MG-149F 12.95 only STAL TRANSDUCER 12/29 V. DC 500 V. 50 MA USA/ 0151 1.95 28 V. DC F/ Comm. Receivers 1)3f 32 1.95 BC 454 COMMAND RECEIVER MOTOR -6 or 12 Volt AC -DC. Heavy Duty reversible 3 In O Mfesaeycles. Corers 75 and SO meter amateur motor with 5/16' x 7/16' shaft. Price: NEW..52.95 FLAW BENEATH SURFACE hand. Price. completo with Schematics- NEW $6.95V 7 TUNING CRANK for Comm. TUNING UNITS If a fis ion or break exists very close to the sur- Receivers 6Se ea. face of he -17 or TU -25 for BC 223 -NEW each material, the reflected pulse occurs SELSYN TRANSMITTER & INDICATOR TU $4.50 within a very short time and may interfere with TU -5 for DC 191 -BC 373- ):E \V.... $3.95 Ideal the original pulse. The transmitted pulsemay over- aaltadlo TU- 7- 8 -9 -10 or 26 for BC 191 -BC 375 - Steam position NEW $2.95 load the oscilloscope amplifier. If the reflection indicator far. occurs almost immediately there is not enough llam. Televi -t RF Unit for BC 312 -1st. 2nd. or 3rd 51.50 time to restore the amplifier to normal sensitivity. sinn. or Com -i Detector Assy. BC 348 -0 51.25 clal tae . An artificial transmission line or other delay Complete with circuit is added in series with the five Inch, crystal trans- ramq\u- . THREE FOR 51.50 SPECIALS ducer to delay the reflection so that it cannot tnsyn Trans., C Me . Unit 6 to 9.1 MIC F/ BC 454 interfere with the transmitted pulse. In the dia- 12 Volt 60 ryclo trans "ice gram, the reflected pulse is shown occurring at a 465 KC IF Iron Core 1st, 2nd. or 3rd. former. and' KC Standard without the delay network, and at b with the wiring instructions. Price: NEW $7.95 955 IF Replacement 456 KC IF lice Wee delay circuit added. 1 -82 Indicator, only $4.95 30 MC Ile F31 or T.V. Broad Band TRANSFORMERS 2.85 MC IF FM Narrow Band Assy. H.F. ELECTRONIC SWITCH Primary 110 Volt GO cycle; 29 Volt Sec. 1 amp $1,95 Patent No. 2,439,651 Primary 110 Via 60 cycle; 29 Volt Sec. .5 amp 51.50 .r,ELSYNS Robert B. Dome, Bridgeport, Conn. l'r!mary' 110 Volt GO eyelet 14 -14 Volt Sec. 715 or 13 mna $4.95 110 Volt 00 cycle. 78411 Size V...... 55.95 Pair (Assigned to General Electric Co.) 231G 1 G0 cycle. Primary 110 Volt 60 cycle; 12 Volt Sec. 1 amp.. -$1.50 -110 Volt Instructions $3.00 Pair In radar, for example, it is necessary to ADDRESS DEPT. RE switch rapidly from one antenna to another. CHOKES This switching may be done effectively as de- Prices are F.O.B., Lima. Ohio scribed here. CHOKE -5.20 11 500 MA (Swinging). 5000V Test.S7.95 25% DEPOSIT ON C.O.D. ORDERS CHOKE -8 H 500 MA Filter, 5000 V Teat The output of each antenna is passed through $8.50 separate and similar channels. Each contains two parallel networks and a rectifier. The tube 132 SOUTH MAIN ST. cathodes are connected across a square -wave generator so they conduct alternately. The par - FAIR RADIO SALES LIMA, OHIO JANUARY, I949 New Patents 821 allel circuits are made to resonate at the radar frequency. The variable resistor R is adjusted so that the total resistance between the L center -tap RADIO TUBES and ground is Ro /4 during periods of conduc- MEjy tion. tile is the impedance of the parallel net - si work LC at the radar frequency.) With this ad- e are attenuated to zero (the- Her816 justment currents All Brand r+e. oretically). During non -conducting periods the added re- AND MONEY BACK GUARANTEE! sistance of L2C2 upsets this condition. There is INTERCOM practically no current flow through this network, therefore attenuation is almost zero. THIS LIST COMPRISES OVER Currents from both channels are mixed in a COMBINATION transformer circuit. The output transformen are RADIO spaced a quarter wavelength from the common 100,000 TUBES line to prevent interaction. RUSH YOUR ORDERS IN ANT 1A7, Sylvania .59 1 H5, Kenrad .59 1 LC6, Sylvania .69 1 LD6, Sylvania .49 1 LE3, Sylvania .79 1 LN5, Sylvania .39 1 N5, Sylvania .59 1 R5, Unbranded .49 at a PRICE 155. Tungsol .49 S0.WWAVE GENERATOR 1T4, Unbranded .29 That Can't Be Beat 39 5, R.C.A. .59 6 tube superhet -3 tube WHILE 3S 4, Unbranded .29 THEY LAST intercom permits corn- $/ /95 5Y3, R.C.A. .39 ANT munication between -- /Y7J/ 1.59 `` 6866, Philco radio- master and up to With 1 sub -station and 6C4, Nat. Union .22 4 sub -stations. 50 feet of cable Extra Sub -stations 6C8, Stand. Brand .69 Original cost $64.50 53.95 each 6H6, Western Elec. .37 6SA7, Stand. Brand .46 MIDGET I. F. Brand .46 65K7, Stand. . - .49 I1` TRANSFORMERS 6 SL7, Philco OF - I Ì Original At discounts 6597, General Elec. .39 List $2.70 up to 86% 6X5, Stand. Brand .49 NOW 400 -500 Kc range 12K8, R.C.A. .57 11/4" square, 3 " high 12S J7, Tungsol .49 H. F. GENERATOR .7+ hi -gain iron core. 2,448,501 36c 12 SR7, Kenrad .29 Patent No. INPUT -A826 Howard J. Tyner, Caldwell, N. J. EACH 14A7, Sylvania .49 t I OUTPUT -A827 (Assigned to Ferris Laboratories) 14B6, Sylvania .49 Specify Type and designers have had ex- Matched Egg Crate 149 7, Sylvania .49 Most technicians Pair Dozen of 100 perience with the mysterious behavior of high - 14R7, Sylvania .49 frequency circuits. Dead spots may appear over 69c $3.95 $29.00 25A6, Stand Brand .79 portions of the dial due to transit time difficulties and h.f. losses. When these dead spots are elimi- 25L6, Sylvania .54 nated by circuit changes. they frequently reappear 35L6, Sylvania .55 at other points of the dial. making it difficult to 1 meg. VOLUME 35W4, Tungsol .37 design an oscillator or amplifier to cover a wide band. j,,,,, CONTROLS 35Y4, Sylvania .59 A switching arrangement is used in the h.f. #- 35Z5, R.C.A. .39 oscillator shown here. A three -way switch is thrown automatically as the tuning condenser is 50A5, Sylvania .69 rotated. The switch changes the feedback circuit -k. .a085 %Q DISCOUNT 50L6, R.C.A. .55 to produce more efficient operation over each Universal with 117L7, Philco .88 portion of the dial. switch 117Z3, Tungsol .69 117Z6, Sylvania .74 -om OZ4, Stand. Brand .59 8016, Philco 1.59 9001, Hytron .39 10014 oto 29c 9002, Hytron .39 Each 9003, Hytron .39 9004, Stand. Brand .59 LI( ORDER INSTRUCTIONS K55B, Hytron .29 Minimum order -$2.00. 25% de- ( posit with order required for all 27, Philco .36 FREQUENCY MEASUREMENT Demand This C.O.D. shipments. Be sure to include Patent No. 2,445,800 Seal of Quality sufficient postage-excess will be 17, R.C.A. .34 refunded. Orders received without 77, Nat. Union .39 Alfred Mortlock, London, England postage will be shipped (assigned to Standard Tel. and Cables Limited, expr.w colon. AU prices 78, Philco .49 London) F.OJ, o.tat. This circuit is effective over the audio range. Substitutes of other standard brands will During each cycle a condenser becomes charged SUPPLY & be made if listed brands are out of stock and then discharges through a voltmeter, which KHVIV rises in proportion to the frequency. ENGINEERING CO., Inc. BROOKS RADIO DIST. CORP. The input tube is biased to block during half of each cycle. During these periods condenser C 85 SELDEN AVE. DETROIT 1, MICH. 80 Vesey St., Dept. A, New York 7, N. charges frmn the B- supply through one of the RADIO- ELECTRONICS for New Patents 183 rectifiers. When the tube begins to conduct, C scribes only the second subharmonic, others may During positive output peaks (such as P in discharges through it and through the other be generated if desired. Fig. 2 -a) the bias is reduced. Therefore, the rectifier. Charging and discharging pulses are The input circuit (Fig. 1) is tuned to an in- grid goes positive and clips the positive peak of filtered by R -C circuits. The meter is connected coming signal of frequency f. The output is a the signal (Fig. 2-c). During negative peaks across A and B. high -Q circuit tuned to f /2. The second triode (such as N), the negative bias is increased and It is often more convenient to have the meter is a class -C amplifier biased to twice cutoff. When there is no clipping. Therefore. only alternate read in proportion to the logarithm of the fre- a signal is applied, subharmonic energy is avail- positive peaks of incoming signal are lost. This quency, rather than directly with frequency. The able at circuit O. Due to flywheel action the is shown in Fig. 2 -c. values shown provide a logarithmic relationship voltage will be nearly sinusoidal (Fig. 2 -a) al- As a result of clipping action, only alternate over a range of 500- 10,000 cycles. though the plate current is composed of pulses cycles are effective in driving the class -C ampli- (Fig. 2 -b). Part of the output is fed back through fier. This increases output at the desired sub- 5.6K condenser C to the first tube to control its grid harmonic. 8+ bias. cT.0ool5 STATIC ELIMINATOR Patent No. 2,444,455 .00025.1. 1 .00025 Emile Labin, New York City and I50K Ross B. Hoffman, E. Orange, N. J. (assigned to Federal Tel. and Radio Corp.) Designed especially for pulse communication, noise or signal, but the desired pulses produce 150K B this receiver can greatly reduce and even com- greatest output. Pulses of other timing such as pletely eliminate static and noise. It includes a static are greatly reduced. resonant circuit tuned to a low -frequency com- Incoming signals and noise are first amplified ponent of the desired pulses. The circuit is in a wide -band amplifier. This is followed by the shock- excited by every incoming pulse, whether shock -excited circuit which has a Q of about r A FREQUENCY SUBDIVIDER CLIPPER PISE IIOIDENING CIRCUIT INDICATOR Patent No. 2,445,161 Vernon H. Vogel, Cedar Rapids, Iowa (assigned to Collins Radio Co.) This frequency subdivider is designed for effi- ciency and simplicity. While the following de- $0. The desired pulses produce greatest WIDE BAND RECEIVER PULSE SHAPER output. F The diode damps out each oscillation after the first half -cycle. The noise which still remains is lost in the clipper circuit which transmits only signals which have greater than predeter- GI O mined amplitude. To produce a greater effect in the pulse indi- 1 I O cator (which may be an oscilloscope) the pulses may be widened in a pulse- broadening Its 0 circuit. This is similar to the previous resonant circuit except that it is tuned to a lower frequency. When it is shock- excited, the output pulses from Fig. 2 this circuit are relatively wide. This receiver can improve the signal -to -noise ratio by about 14 db. For GREATER Earnings.. LEARN RADIO- ELECTRONICS This fast- growing science of RADIO, TELEVISION, RADAR and ELECTRONICS, offers tremendous opportunities, and in no industry is I RADIO -ELECTRONICS more important than in aviation. A skilled technician / who knows the modern application of electronic devices, as used in the aircraft industry, is always in demand ... not only in aviation, but in many other / industries. Many large organizations call on Spartan regularly for graduates. Often, students are hired months before graduation. Don't confute the RADIO- ELECTRONICS course offered by / SPARTAN with other courses, offered anywhere! As a graduate from this I famous school you will know the application to industrial control devices; / to the search for petroleum; and the important uses of radar, television I and other electronic equipment. / SPARTAN offers two complete and thorough courses. / You will work on the most modern and complete equipment. You will build equipment. You may join the SPARTAN "Ham" Club. Either / SPARTAN'S 21 years of teaching civilian and course prepares you for Federal Communication Commission army personnel is your assurance of receiving the license / best possible training in the least possible time. tests - first class radio telephone,, second class radio telegraph, or class / You'll not need MORE than Spartan training -you "B" radio amateur. / cannot afford to take LESS. BIG CATALOG -Pie& NAME AGE_ SPA R TANE SCHOOL OF RADIO AND ELECTRONICS ADDRESS I CITY SCHOOL of AERONAUTICS COLLEGE of ENGINEERING STATE MAXWELL W. SAVOUR, DIRECTOR ADDRESS DEPT SE -19 - I Dept. RE -19 . TULSA, OKLAHOMA G. I. APPROVED -Write TODAY for Complete Information JANUARY, 1949 84 Radio-Electronic Circuits NOVEL 12 -WATT AMPLIFIER PHONO AMPLIFIER ing relay can be heard clearly through the speaker. Seldom do 12-watt audio amplifiers When used with a high -level crystal The tone of the buzzer usually can be use transmitting -type output tubes as in pickup, this amplifier produces about 5 Radio and Hob- watts adjusted over a small range by varying this circuit taken from output. Inverse feedback is used the voltage. bies (Australia). The tube line -up con- from the output transformer secondary spring tension and battery sists of a 6SJ7 voltage amplifier, 6SN7 to the first cathode. If the amplifier .4. paraphase inverter, 6SN7 push -pull squeals, reverse the secondary connec- 0001 22.5-45V KEY driver, and push -pull, triode -connected tions. Varying the 3,300 -ohm feedback o Upp 1110----A--7 807's. This amplifier delivers up to 12 resistor may improve results, but if its SPST RELAY watts output with negligible distortion. value is too low, the circuit will motor- Input terminals are provided for phono- boat. This makes a simple and satisfactory graph and radio tuner. All inputs are The 6F6's are connected as triodes to arrangement for the beginner who is high- impedance. reduce their plate resistance and pro- learning code. Inverse feedback is developed between vide better listening results. All cathode ROBERT F. CUTA, one side of the voice -coil winding and resistors are unbypassed to add addi- La Crosse, Wis. the cathode of the input section of the tional stability. (The buzzer may create interference phase inverter. With feedback, about 1.5 EDGAR SCHOENIKE, to nearby radios, so be careful to avoid volts of input are required for full out- Winona, Minn. offending the neighbors.Editor) put. Without it, only 0.15 volt is re- quired. The signals on the grids of the 6C5 6SL7 6F6í23 807's are balanced by varying the set- ting of the 20,000 -ohm potentiometer in series with the plate load resistors of TONE VC the driver stage. Feed an oscillator sig- 2MEG 500K nal through and the amplifier compare .ows the a.f. voltages on the 807 grids with MICA a v.t.v.m. Adjust the potentiometer un- PM SPKR til the voltages are equal. o IK If a suitable capacitor C is inserted in INPUT 0-4 ---IH - 6Kr.PLATE -PLATE the feedback circuit, the gain of the 15/450V IOW TRANS stages within the feedback loop will 22N 2W vary inversely with frequency. The r amount of feedback is controlled by the series resistor R. Values of R and C, on the diagram, are selected to give bass TWO -TUBE RECEIVER boost below 250 cycles of 6 db per oc- tave when one end of the loop is con- The unusual feature of this 2 -tube nected to an 8 -ohm voice coil. Combina- regenerative receiver, which has an tions of 4,700 ohms -0.1 µf and 2,200 amazing amount of sensitivity and out- ohms -0.2 µf are for 15- and 2.3 -ohm put volume, is in the r.f. tuning section. voice coils, respectively. Instead of the usual high- impedance an- The 6SJ7 stage is designed to have the same bass -response characteristics toL3 2 15N 114 (2) WIRELESS CODE PRACTICE as the feedback network with C in the .00025 x LIL2 circuit. The gain at middle frequencies A battery and a normally closed 6 is 2.5 times or about 8 db. Close S3 and s.p.d.t. telephone -type relay hooked up 2.2MEG short out the 6,800 -ohm resistor for full as shown make a good high -pitched 365 aut gain from this stage. buzzer for code practice. If a nearby There are four positions on the radio is turned on and tuned to a clear PHONO -RADIO switch Si. Two of these spot on the band, the sound of the buzz- 6SN7(2) 807(2) ANT 50 -75FT MAG SPKR -IKn 33K 221( 30H/20MA 8 /600V 6SJ7 tenna coil, two similar coils are used for 51,52 GANGED 107K the antenna and grid circuits, as in RADIO e--14.02 51 Grace's crystal receiver (RADIO -(RAFT, .1 Pu January, 1948). L1 and L2 are secondaries from 3 6.8K Meissner 1410 -10 coils. The primary of each assembly is removed. L3 is a pri- LO PU mary replacement winding, Meissner 4 14 -6852. L3 slides over L2 so that it IMEG 3.3K.R 2.2K can be set for the best regeneration point. Coupling of Ll and L2 can be varied to control selectivity, but the two should be kept as close together as 5 }1- possible. 5U4-G 20H/175MA I 5 For utmost sensitivity connect to- 000 l gether the two points marked X; if 5V/ 3A 117 V AC w selectivity is needed, do not connect 6/. \6 them. ö 850V 270K 16 /600V g-175MA As the diagram indicates, I used a o 4 !< 1,000 -ohm magnetic loudspeaker. A are connected to the radio input ter small PM speaker can be used instead, 6.3V/2.5A TO minais and two to the output of the 807FILS if a suitable output transformer is 6SJ7. Si and S2 are ganged so that the added. feedback capacitor C can be included in 6.3V/2A TO OTHER FILS JOSEPH AMOROSE, the feedback loop for added bass boost. Richmond, Va. RADIO -ELECTRONICS for Theory and Resign U. H. F. NOISE DIODE Noise generators using standard tem- BUYING SURPLUS perature- limited diodes have been used MEANS SURPLUS SAVINGS in laboratories for measuring the sen- ...... a sitivity and noise factor in receivers. Brand New! Kenyon Filament Such generators were often limited in . Transformers their high- frequency range and were -.-+ For 304 TL's. Will aperal suitable only for narrow -band ...,. two 304 TL's. etc. Sec.. tuned " Volts, C.T. at 60 amps. PH 115 Volts-80 cycles. Shp;.. circuits. w4. 26 lbs. The Type TT -1 co -axial noise diode --4-: $8.95 was developed to overcome these limita- WESTINGHOUSE TERMINAL STRIPS tions. This tube, developed by RCA and 12 a nect ions, molded black Phenolic. l:ra,- screws, now being manufactured by Eclipse - terminal 1% x 1% x 9'. Slips. ls'l.. 1 lb. Pioneer Division of Bendix Aviation 99c 1 EXCLUSIVE Corp., goes up to 3,000 mc and is suit- *Wide -Range G.E. PICKUP CIRCUIT Synchronous 13x8xax8 MFD -600 V able *Scratch 1 (Self- Rectifying) OIL FILTER for untuned wide -band circuits. Suppressor New circuits enable you to attain VIBRATOR *Volume 1 full benefit from the new G -E Ved. Hermetically Sealed CONDENSER pickup. 100 milliamperes. Expander able Reluctance Magnetic flood for Pert ect for a life t i III , Employs an exclusive, humless pre. Does not require rectifier power supply -In the sae 1 equalised pre -amplifier to produce tube. Fits standard octal price range as Electrnh Supreme per- tube socket. Orig. Gov't tics. Packed Unit Shp,: the most satisfying musical amplifier price over $5. Skips. wt. WI. 4% lbs. formance the world has ever known. If you _Iba. each with any vari are a perfectionist, you are the one 6 Volt ModcI..51.29 $3.75 able reluct 1 for whom the ACA .1000E wes de- 12 Volt Model....99c 3 for $9.95 once pickup. signed. Send for technical literature. 1 HEINMAN POWER CIRCUIT BREAKERS OF Like newt Protect your rig trout blown -nil to .s. AMPLIFIER CORP. AMERICA Slipping wt. 21 lbs. 5 amp, 115v Net 99c 398 -10 Broadway, New York 13, N. Y. 20 amp. 115e Net 51.39 NEW! RL -42.B ANTENNA REEL BRAND NEW SURPLUS! GUARANTEED! Motor & Gear Box Perfect Beam Rotator Lightweight (4 lbs.l, easy mounted. 3/4 RPM, HI- TORQUE magnetic clutch. will reverse with s.p.d.t. switch. Also for barbecue spit or door opener. Many other uses. ELECTRIC MOTOR Shpg. wt. 5 Ihn. Plus $4.25 40c Pos loge Shipment made by either fast truck freight or press rollers, or iv Parcel 1.,n1 if postage is Included with and order. No deposit required on C.O.D.'S. No orders 10.5 $2.85 Handling than $2.50. please. GOV'T COST. $40 Operates on I10V AC, 60- cycles ELECTRONIC SALES COMPANY Noise -factor measurements are made (Requires 5559 West Adams -Dept. RC -1 Rersible. Slfe - LO kg t Clutch.er by connecting a properly loaded tem- With Full Instructions. Los Angeles 16, Calif. perature- limited FOR ROTATING HAM. FM. TELEVISION AN- / diode across the in- TENNAS AND MANY OTHER USES. put of the receiver and measuring the FB for that sew QUAD receiver noise output with an output BARGAIN RADIO, Dept. BR -3 meter. After noting the reading, the 249 N. luani ta Los Angeles 4, Californis GREYLOCK diode is turned on and its filament cur - A Dependable Name in rent increased until receiver output is twice its original value. The diode anode RADIO current is used as the receiver noise MADE EASY! RADIO TUBES GT. Glass & Miniature Types factor after it has been corrected for A JRI Trainer All Tubes in Individual Cartons transit time and spurious A NEW APPROACH to radio receiver repairing. Here receiver re- is METHOD of radio repairing that can be LEARNED 5Y3GT I2AT6 1115 QUICKLY -Begin repairing immediately. The electronic 6AT6 I2BA6 1T4 sponse. 1213E6 1U4 field is wide open. Prepare yourself for a 0001) INCOME 6BA6 The 100 -ma maximum anode current NOW! Discover for yourself that radio repairing is EASY 68E6 12K7GT 155 TO LEARN by this NEW 5fKTHOD. Send for the ZRI 6SA7GT I2Q7GT 354 makes 12SA7 3Q4 noise factor measurements pos- Home Trainer TODAY. 82.00 postpaid or plus c.o.d. charge. 6S17GT Satisfaction guaranteed. 127 sible up to 20 db. The transit-time re- 6SK7GT 125S0Q 7 12ÁF6 6SQ7GT 39. duction is 3 db at 3,000 mc. THE JRI TRAINERS 25L6GT 128ÚB P. 0. Box 2091, Dept. 100 -A, Chicago 9, III. 6V6GT 35W4 3585 The co -axial diode 6X4 35W4 3525CT each consists of an 6X5GT SOBS 35256T outer conductor (the anode) and a con- 12AöGT 50L6 11723 centric inner conductor. The ratios of All 39e Tubes may be pur. We have increased our SPECIAL OFFER! chased In lots of 100 as- the diameters of the conductors sorted. at $35.00 per 100. pro- production so we are duces a 50 -ohm characteristic impe- 8A7 6A U6 6G6G dance, making the diode suitable for di- now able to again make BACS 6BH6 6SNi GT BAKS 61316 12AÚ7 49c rect connection to the antenna terminals immediate delivery on BAQS 6C6 25Z5 GARS 6D6 each of many high-frequency receivers. The Wright Verified Speakers 6A15 6BL7GT 6AL5 3.2 -volt, 2.5 -amp. filament current en- with the IHSGT 19T8 11717 ters the diode through a lead inside the INSGT 701.7 6L6GA 59c inner conductor and returns through 321.7 84 53 each the inner conductor itself. SPECIAL!! 6BG6G $ .89 Further in- Standard Replacement VOLUME COIPIROLS, formation on this tube is to be found in All sires. iqk' shaft. less switch, each S .24 With SPST switch. each .34 the March 1947 issue of RCA Review. With DPST Switch, each .44 PM SPEAKERS Lese Trees. 4' with Alnico V Magnet $1.14 with Alnico F Magnet 1.14 6' with Alnico V Magnet 1.49 One billionth of an ampere can be meas- 3' PM with plastic cone. and 8 -oa Alnico V Magnet 1.35 ured by a new microammeter developed 6'x4' PSI with Alnico 5' Magnet 1.19 by RCA. The instrument is expected to Mounting WEBSTER Ail Pickup. plastic arm 1.49 Bracket SELENIUM RECTIFIERS be important in various branches of re- 100 Ma. .. .59 write for literature 75 Ma. .49 search. It may be used with multiplier TERMS: Net C.0.0., F.O.B. N.Y.C. 35e Handling phototubes to measure light intensities Charge on all orders under $5.00 and the density of in WRIGHT, Inc. Write for Bargain Catalog C.I gases and atomic 2234 University Ave. research for checking ionization -cham- GREYLOCK ELECTRONIC SUPPLY CO. ber currents. St. Paul W4 Minn. 30 Church Street New York 7, N. Y. JANUARY, 1949 861 Theory and Design RADIO AMATEUR NEWCOMER MULTIMETER SHOWS ONLY DESIRED SCALE the only comprehensive book for Ever since the invention of the mul- the beginner! timeter, radiomen have complained that You need no other book to get your license and a single meter face with enough scales get on the air. Ideal for those lust getting started, to cover all the ranges is confusing and or getting interested in amateur radio. time -wasting. ABSOLUTELY COMPLETE The Simpson Electric Company has How - to - build simple Il put on the market a multimeter de- equipment for a complete station all newcomer signed to solve this problem. Known as bands. the Roto-Ranger Model 221, it has 18 Operating instructions. i different ranges, measuring voltage, Simple theory. Complete section of current, and resistance. Instead of hav- study questions, including ing all the scales printed on its face, those needed to post the license exam. there is a mask over the entire meter U. S. A. Amateur rodio face. As the photograph shows, a slit regulations in is enough to re- Millen be ter editor, of the mask just large RADIO 11.4 NnnooK. veal a single calibrated scale. 100 AT YOUR DEALER. On direct orders from The cutaway view of the rear of the us please add 10c for mailing. panel indicates how the scales are A front view of the Roto- Ranger Model 221. changed. A drum behind the meter has 18 slotted recesses, each containing a The contacts are molded into plastic volt, ohm, or A 1303 KINWOOD ROAD. SANTA SARSARA, CALIFORNIA single current scale. discs and are silver-plated. Separate molded wheel on the end of the drum is bakelite pockets are provided for each scalloped, with each scallop recessed to resistors, HEADSET H -16U SPECIAL of the shunt and multipliér 5000 ohm Dual. Headset 11-16 /U fit a 3/16 -inch ball bearing. The ball as well as for each of the batteries. -most sensitive phones built- bearings comprise the indexing mech- photograph does nolseproof-may be used as a Though the cutaway sound powered intercom - Also anism, which holds the drum securely not show it, switch and rotating scale used with simple Niel to make complete radio receiver -light. in any of its 18 positions. are completely enclosed. No wiring is durable. efficient, molded. soft neoprene caroms. shaped to Movement of the drum is controlled visible except that connecting equip- snugly and comfortably envelope A site mitre ear. Everyone BRAND entirely by the range- selector knob. ment inside the housings with the four NEW. Complete with Illustrated manual. Send money pair of beveled gears transmits motion pin jacks, which are mounted on a small order or check today. Special per pair $1.89 of the selector- switch shaft to a shaft panel of high -dielectric material. Plus 25e each for postage which moves the drum. The 18 ranges of the Roto-Ranger ATTENTION Amateurs - In addition to the single -scale meter measure up to 5,000 volts a.c. or d.c. at Experimenters -I nventors feature, the Roto- Ranger incorporates 20.000 ohms per volt; 10 amperes d.c.; Cut your cost on radio supplies and equipment In an unusual range switch. Unlike most and 20 megohms. An output scale is half. Clip coupon today. Hundreds of "hard to get" war surplus items along rotary switches, it is entirely enclosed. included. with the beet in standard brand equipment -all at great savings to you. Let us know your particular requirements. IMMEDIATE DELIVERY. PLEASE PUT MY NAME ON YOUR MAILING LIST FOR SPECIAL BULLETINS. NAME ADDRESS ZONE CITY STATE NIAGARA RADIO SUPPLY CORP. 160 Greenwich St., New York City 6, N. Y. Get 1hi5 Valuable Book R E Expia n for Merely Examining Latest sets Coynes NEW Pay- Raising Mechanism which keeps rotating dial and switch in step. Note encased multiplier resistors. Here's a PRACTICAL set of radio hooks just off the press! Gires you "know how" on everything in Radio today. Basic principles to newest in Televi- sion and F.M. - how crntstruct, install. service. Latest trouble - shooting methods. 1000 illustrations. PROBLEMS OF ELECTRONIC BAKING over 1500 pages. ideal for reference or home train tog. To prove how valuable these great books can be to you. Coyne will give you a FREE copy of o Recent experiments in England have cause all parts of the bread are heated new. helpful "150 New Radio Diagrams Explained" to of for looking or the 5 Vol. Set. OFFER LIMITED drawn attention the problems bak- at about the same time and to about the -ACT NOW! We will send you 5 vol. set AP- ing bread electronically. The tests were same degree, no crust can develop. But PLIED PRACTICAL RADIO for 7 days FREE ex- amination together with Radio Diagrams. Look set conducted by the British General Elec- most people seem to prefer bread with over for 7 days. If you like It send $15 cash, or $3 after 7 days- and $3 monthly until $16.75 is paid. tric Company, Ltd., using standard If you don't want one set, return it and you owe high -frequency dielectric heaters. NOTHING. Either way you One of the most keep Diagrams Rook Free. interesting factors SEND NO MONEY! Cou- in electronic baking is illustrated by pon asks to see books free and the photograph of two loaves of bread. got roar gift book FREE for doing it! Send The loaf on the right, baked by ordi- BOOK coupon NOW! nary radiant heat common in today's COUPON EducationalBook Publishing Dlvisiod COYNE ELECTRICAL & RADIO bakeries, looks normal in every way. The SCHOOL, Dept 19 -TI, loaf no 500 South Paulin' St Chicago 12 Illinois on the left, however, has crust. OK. Send me. postpaid. Coyne's new 5 volume set. It was baked by high- frequency dielec- "APPLIED PRACTICAL RADIO" for 7 Days FREE TRIAL per your offer. Also send. absolutely FREE, I tric heating, one characteristic of which "150 New Radio Diagrams Explained" as a gift. is the into the I NAME AGE that heat penetrates ADDRESS very center of the heated object even TOWN ZONE STATE before it acts on the outer surfaces. Be- How electronic and ordinary baking compare. RADIO -ELECTRONICS for Theory and Design 187 a crust vcept when it is used for sand- wich making or other special purpose. Another difficulty is placing the bread DURABLE! and electrodes in their correct relative RUGGED! positions. For uniform heating, the air gap between the electrodes and the A POWER SUPPLY heated material must be uniform at all THAT CAN REALLY "TAKE /T of points, and it should be very small. Since bread batter is not rigid, it must be held in a container. Baking tins can- not, of course, be used, since they shield the bread electrically. Wood and card- board containers were used in the re- cent experiments with some success, but Model "A" 6V 15 Amp. or 12V 21/7 Amp. DC filtered from 105V to 125V 60 cycle power line. This model has proper rectifier, choke coil, condenser and trans- former to provide heavy instantanequs output and still maintain rated output under unusual load and heat conditions. Ideal long life power supply for testing auto radios with solenoid tuning and tone controls; 12 volt marine and aircraft radios; tele- phone circuits, laboratory apparatus, etc. "Oven" is designed to keep load constant. Write for complete information a fully satisfactory solution has not yet been found. Bread creates additional difficulties because it rises during baking. Any un- ELECTRO PRODUCTS LABORATORIES even bulges cause some parts of the loaf Pioneer Manufacturers of Battery Eliminators to come closer to the electrodes than 549 W. Randolph St. Chicago 6, III. others, with the resultant danger of local burning. The photograph of a loaf of bread being placed between the elec- trodes shows how this problem was at least partially solved. The sides of the container are made rigid so that the loaf rises only in a vertical direction. Then the electrodes are placed at the sides of the container. Heating time is extremely important, ABSOLUTELY NO KNOWLEDGE OF RADIO NECESSARY much more so than with ordinary radi- YOU NEED NO ADDITIONAL PARTS! ant heating. Heat continues to be gen- THE PROGRESSIVE RADIO KIT Is the ONLY COMPLETE KIT volts ACS are employed in these circuits. The circuits are designed in bread all the time it is - Operatef 110 -120 erated the oc. Contains everything you provide excellent performance. Altogether, fifteen need. Instruction Book. Metal circuits are constructed, including 11 r 1 audio between the electrodes and undesirably chassis, Tubes, Condensers. Resisters and all other n mplifier and 3 transmitters. The sets start With simple essary radio parts. The 3e -paie Instruction Rook writ- circuitsis 1 tube plus rectifier. gradually grow high temperatures may develop if it is ten by expert radio instructors and engineers teaches you and finish with several examples of radio sets to build radios in a professional manner. Te first Ear sing three tubes plus recto fir. long. n Each left in too Since the heat initially ilk built is simple one-tube detector receiver. u PROGRESSIVE RADIO KIT . ONLY 514.7E < ceeding circuit i c0 ate w arrangements of de- centers within the loaf, the outside of tectors. RF and AF amplifiers. This kit is excellent for FREE OFFER learning the principles of receiver, transmitter and SPECIAL with mpegfl.r n. i ols Electrical and Radio Tester sent absolutely FREE the loaf does not necessarily indicate in PLUS FREE membership in Ae Xt. e 1 sed Óetec'torcaor u each Progressive Radio Kit. Progressive Radio Club. Entitles you to free expert ad- how well the bread is baked. If the including plate and infinite-impedance. licensed radio techni ramotterai grid tmsodesignedi with Hartley and Arm - vice and consultation service with oscillators, using control-grid Write for further information or ORDER your KIT process is used commercially, automatic d Both vacuum tube and selenium rectification NOW! timing devices will be necessary to pre- WE PAY POSTAGE ON PREPAID ORDERS C.O.D. ORDERS SHIPPED COLLECT vent drying, toasting, or even total of the loaf. It is interesting Send for Your PFREE catalog and burning ATTENTION RADIOMEN!! I1DEALERS to consider that if the bread were RADIO KITS AMPLIFIER KITS . FM COIL & CONDENSER KITS RESISTOR KITS allowed to toast, it would actually de- CONDENSER KITS RADIO TOOL KITS FM -AM CHASSIS SPEAKERS RADIO velop a crust on the inside! PARTS PORTABLE RADIOS CAMERA -RADIOS TUBES AUTO RADIOS HOME RADIOS TELEVISION SETS TELEVISION CABINETS TEST EQUIPMENT FM The practical results of high -fre- TUNERS quency baking are fairly encouraging. Baking time for an individual loaf is CO. less than 5 minutes. However, because PROGRESSIVE ELECTRONICS the heating kills the yeast almost in- DEPT. RE -20 497 UNION AVE. BROOKLYN 11, N. Y. stantly, very little rising takes place during baking and a longer "rising" "! A.sg,%aa time must be allowed the raw dough "POCKET TALKIE TALK -SING -PLAY DRADIONY REALLY WORKS -talk and hear 2 -10 REAL RADIO MIKE! At- miles or snore FITS IN YOUR sVitl, the NEWEST before baking so the yeast can work. - taches In a )iffy. FULL INSTRUCTIONS GIVEN! POCKET! Uses flashlight batteries. SWELL FOR PARTIES " -"CUT IN ON OR Although the results are interesting, ABOUT SIZE OF 2 PACKS CIGA- KID" REGULAR NETWORK PROGRAMS OR 51. 11 PUT ON YOUR OWN BROADCASTS! AMAZE R(cash Fke kt or MO) FEND FRIENDS -REAL M UN! ARN RADIO General Electric states, baking does not ($1.52 C.O.D.) for F2 to read plans. BEAUTIFUL SILVER assembly Ins.. pictures and flans YOURBROADCASTING! PI.ASTIC Detachable base -6 foe wire! appear to be an immediate commercial price lists with D..fAILED CATALOGUE ON 135 OTHER an PRODUCTS SUCII AS: ($1.00 refunded on parts order) SEND NO MONEY R2» COD plus post- 3 -tube Pocket Radio Cigar Box Transmitter. Dash Can we postage! application for dielectric heaters, espe- Radio Garage Door Openers. ¢e or send $2.99 and pay Transmitter. ORDER ownI REAL RADIO MIKE TODAY -N MOTOR INDUSTRIES. Dent. CW -1. Kearney. Nebr. cially when its high cost is considered. MIDWAY CO. Dept. MRC -1. K , Nebr JANUARY, 1949 881 Miscellany BRITISH "RADIO NURSE" FACTORY AIARD-TO-GET PARTS L. SPEAKER POWERFUL ALL-PURPOSE INDUCTION ' 1!x`4t REPAIRS MOTOR IDEAL FOR E%PEaI 101 USES `EO SINCE 1927 Sturdily constructed to precision oNE standards, xis self- starting shaded pole Inductionian Pow- RM -4 RECORDING MOTOR. Back again by popular erful enough foor numberumber of demand! This terrific little motor at truly amazing of these are: Tim. Price. Heavy duty 110V, 60 cycles. Silent operatmg Devices, Current Interrupters, Einglectric Fans, Electric Chimes, for WIRE, TAPE or DISC RECORDING. 33a sq. Window Displays. Photocell Contro x 2% ". Less turntable, mtg. plate & reduction drive Device°, Electric Vibrators, Small wheeL Shpg. tut. G lbs. 34.96 Grinders, Buffers and Polishers, Miniature Pumps, Mechanical Mod- els, Sirens, and other applications. HIGH FIDELITY CRYSTAL MICROPHONES Consumes about 15 tt° of The microphone buy of the year! Made for a andd has a speed of 3,000 world famous hearing aid manufacturer. Now at r.p.m. WhM geared down, this a sensationally low price. Sensitive diaphragm sturdy unit constantly deep, ideal for an -Ichnl tr loadedodate type. Small size (132' O.D. IA' With 200 lbs. dead weight-THAT'S POWER! REGULAR, LAPEL or CONTACT MIKE or as 14 convenient high shaft PILLOW SPEAKER. Rubber shock -mid. metal hasDimensionsconvenient nt ngstud.; i13/4. aló g housing 98e by 3/16' diameter, and s In° Ifall in ell- frame. Leas retaining bearings. for 110.20 volts, 50 -80 Shp. Wt. 2 lbs. ITEM NOC147only. SHOCK MOUNTS- Moulded live rubber In sturdy YOUR PRICE $2.45 metal frames at money sin Mg prices. 1" mtg. holes, 3/32" hole... ea..1 O; 12 for 61.00 1 %' mtg. holes. Y.' hole... ea. . 1 5; 8 for 61.00 ULTRA MAGNET wt. 2 2.1 mfg. holes. tA' hole.ea. 49 (Shpg. lb.) LIFTS MORE THAN 20 TIMES INSULATED STAPLES. Handy sire 47 ( %' x %I. ITS OWN WEIGHT Sale price, per 100 $ .29 LITTLE GIANT MAGNET per 1000 2.89 lbs. CO FITTING M.359 (83 I AP). Low loss poly. Lifts 5 easily. Weighs 4 os. -AXIAL of ALNICO new high aaggnn tlo Priced for quick turnover $ .29 steel. Complete with keeper.World's 4 for 1.00 most powerful magnet ever made. ARC 5 /BC 457.8.9 P.A. COILS. Nos. 7991, 7247- The xperimenter and hobbyist will find hundred' of excellent uses for 48-49-50; ranges from 1.5 to 9Mc. They're going, high quality permanent magnet. fast! Order yours now! .39 Measures 13/4 x 11/2". Ship. Wt. Kit of all Ere 1.49 thislbs. ITEM NO. 159 YOUR PRIG[ $1e 25aaS FREE SUPPLEMENT CHECK FREE SUPPLEMENTS DESIRED GENUINE "RECORDING PARTS & ACCESSORIES" MICROPHONE TRANSMITTERS Regular telephone trans- "ALNICO MAGNETS" taken from a large Courtesy !British Inf ormation Service "HEARING AID & MINIATURE PARTS" t ittersnt supply company's tocckk. Work perfectly This English version of the Radio Nurse is an u "GEARS, SHAFTSR &NPULLPARTS"EYS" usered on P.A. systems, ordinary . The is up Ssyysteme, inter-communica- intercom. master unit set mine" of relays, tions seta. short-line tele- some PE -157 POWER SUPPLY. A "gold phone circuits. of spot near the mother and the remote switches, selenium rect., jacks, etc.. incomplete tofa m hung on the handlebar of the baby's carriage. army unit. Surplus stock at a terrific saving to yon. 'uphone lines, also to talk Portable hinged lid metal case (B"x8'x12') OD through your own radio or finish. descriptive 173p. TECH as dictaphone crackle PLUS plellup. Useful replace. TELESETS FIXED RIGHT! MANUAL. Shp& wt. 20 lbs. 52.49 m ants batteryopersted rural telephone lines. A new racket involving phony tele- THESE ARE GENUINE JUMBO RADIO PARTS ASSORTMENT MADE BY vision repairmen is being foisted upon A grab -bag of radio values that will delight you. KELLOGG, WESTERN ETE RICE AND SSTROMBERG. OMBERG. 17 lbs. of useful items at one bargain price! excellent A television set owners in a number of com- émremarkable rkÑC and onepP° seldom offered` In1the New & dismantled Radio & Electronic Wt. 1 °1D. ` ponents. 17 FULL POUNDS OF COILS. ITEM No.NO. . W cities, Radio & Television Weekly re- SOCKETS, WIRE, SPEAKER ACCESSORIES. YOUR PRICE $l HARDWARE. RESISTORS, CONDENSERS, ported last month. TRANSFOR5IF,RS, etc., etc. All these and WATTHOUR METER Usually operating in pairs, thieves MUCH MOItE (Shpg. wt. 21 lbs.) ONLY $2.95 completely overhauled and a. vready for immediate service. spot prospects by looking for TV an- olt, for POWER RHEOSTATS. The rheostat of a thousand volt. 00 2 -wire A.C. tennas. Then, usually during the week uses. Indispensable around the shop or home for Simple to install: controlling small motora. electric trains, toys, etc. line when the head of the family is at work, 2 wires to the load. Sturd- Famous make, wire -wound % shafts. constructed heavy 25 watt; 20, 100. 175. 370 or 900 ohms, ea. .89 niera high they ring the bell. The conversation 50 watt: 2, 25. 50, 300, 500, 1250, 2K, 311 wide, 5" deep , Westinghouse. goes like or 7500 ohms ea. 1.29 G. E. Fort Wayne, Sangamo with the housewife this: Ner available make. Shp. SPECIALS!! 25 watt; 250 ohms ONLY .39 W t. 14 lbs. "We understand from your husband 6 for 2.98 ITEM NO. 33 50 watts, 15 ohms ONLY .98 YOUR RICE... $5.95 that you've been having trouble with TUBES AT NEW LOW PRICES!! your television receiver. We come from STOCK UP NOW at up to 80% off list. Bargains AMAZING BLACK LIGHT!! without equal. Perfect condition. GUARANTEED Powerful 250-Wan Ultra -Violet Sourest the service department." FOR 90 DAYS! Unsealed cartons. practical "Yes, we have been having some #27, 35, 39, 77, 85, 5W9, SAT, 6116, 6K7 urcce of ° ulä:violet! light or 8:5 general experimental and enter- .39 tainment use. Makes all Buono. trouble." #41, 78, 1A7. 5U4. 5Y4, SAS. 6137. 6C5, cent subatances brilliantly lumi 615. 68'5. 605, 6J5. SEAT. 65D7, 6S117, No transformer f any The two phony repairmen then make OSE7. 6117, 7A7, 788, 7Y4. 12SK7, 12317 kindant.needed. Fits any standard or 50ß5 .49 lamp socket. Brings out beau- a pretense of examining the set and tiful opalescent hues in various TUBE CARTONS: tines of materials. Swell for announce it will have to be taken Miniature ( l' sq. x 2%') per 100 .98 etc.; that GT size (1%" sq. s 3V. ") per 100 1.25 o(Staini unique ° lighting efcts. back to the repair shop. They walk out Medium WA' sq. x 4%'( per 100 1.49 B ela only. Shp. Wt. 2 lbs. Large ( ITEM NO. 87 re- 2' sq. x 5') per 100 1.79 YOUR PRICE $95 of the house with the television ceiver, and that is the last seen of them RADIO PARTS KIT WESTERN ELECTRIC BREAST MIKE 31. B. F. Antenna & OSC COILS. 10S tine air- or the set. .98 craft carbon microphone.e. v It weighs set owners should be #2. SPEAKER CONES 4'to 12'moulded only 1 lb. Television & free -edge (magnetic incl.). Less Mike comes and has 12 -wayM °untingswivel- warned of this racket. They should be voice coils. Kit of 12 amid. 2.00 ing adjustment that It can be #8. KNOBS; wood & bakelite; set. screw adjustedhere are to ádesired position. advised to check the credentials of any & push -on types. Kit of 25 asstd. .98 woven one goes WAFER cans neck. the other repairmen who come around. Other- #9. SOCKETS; 4 to 8 prong. Straps n be snapped o Kit of 12 asstd. .25 and off quickly by an ingenious be cured per- #10. VOLTAGE DIVIDERS; Multi - arrangement. wise, the trouble may tapped; high wattages, of 10 excellent kit asstd. 1.98 adapted for broadcasting or manently by the theft of the set. #11. SHIELD CANS; for coils, tubes, private transformers, etc. Kit of 15 asstd .98 onting breastplate, It can be #20. SPEAKER REPAIR KIT. Save used mes complete -with 6 -foot cord Moat -needed inventions of 1949, ac- time & money with this professional plug. kit. Contains: 25 mtg. rings, 25 voice and herd bber Finished in herardlzed plate, ru table. Shipping weight, 2 lbs. cording to the National Inventors Coun- coil forms, 10 spider., S yds. felt strip, ITEM NO. 152 20 chamois leather segments, kit of 16 YOUR RICE $1,45 cil, include a number of improvements shims & tube of cement. All for 2.49 #27. PRECISION RESISTORS. Famous and ideas in the radio -electronic field. HUDSON SPECIALTIES CO. I makes. wire-wound -4- or - 1% Ohmage' to 400E. Kit of 10 asstd. 1.98 40 West Broadway, Dept. RE -1 -49. New York 7, N. Y. E First among these is simplified fre- MINIMUM ORDER $2.00 I have circled below thenumbers of the items I'm I 20% deposit required on COD's ordering. My full mittance of S (in- I quency control of radio equipment, Please add sufficient elude shippin charges) Is enclosed (NO C.O.D. postage. ORDERS UNLEFSS WITH A DEPOSIT.) either with synthetic quartz crystals or Components no radio amateur or professional can be without, at prices you can't afford to miss. OR my deposit of R fs enclosed (20 S magnetostriction units or some other Order your required). Ship rder C.O.D. for balance. NO O.O.D. kits now! ORDENS FOR LEES THAN $5.00. RE SURE TO IN. CLUDE SNIPPING means, and new construction methods Circle Item No. wanted: ST 153 33 for ultra -lightweight radio equipment. Other needed inventions are satisfac- LEOTONE RADIO CO. Name tory miniature batteries and a high- 65 -67 Dey St., New York 7, N. Y. AddresS A Please Print speed electronic telegraph printer. WOrth 2-0284 Clearly more efficient collapsible field antenna City State was also listed. eenaommiume M MMM M M m LMn- '-.M I RADIO -ELECTRONICS for Miscellany 189 ELECTRONIC LITERATURE OPPORTUNITY AD -LETS Advertlegmente In this section met 25c a word for Any or all of these catalogs, bulletins, each insertion. Name, address and Initials must he included at the above rate. Cash should accompany THE HOUSE OF and periodicals are available to you if all classified advertisements unless placed by an you write to us on your letterhead (do accredited advertising agency. No advertisement for less than ten words accepted. Ten percent discount not use postcards) and request them by six Issues, twenty percent for twelve issues. Objec- tionable number. is or misleading advertisements not accepted. It necessary to send only the Advertisements for February. 1949. issue, must reach number of the item you want. We will w not later than December 24, 1948. forward the request to the manufac- Radio- Eleetrenlet 25 W. Broadway, New York 7, N. Y. TUBES turers, who in turn will send the liter- ature directly to you. This offer void SELECTED GROUP OF MEN. GRADUATES OF WELL - known trade school, desire employment in Radio Field. GEORGE W. KLEIN after six months. Will travel anywhere. Qualified in radio servicing. Instal- lation. test Instruments, circuit operation, etc. Contact Placement Dept.. Easton Technical School, 888 Purchase 8748 Linwood Ave., Detroit 6, Mich. Street. New Bedford, Mass. 1 -1 -1949 ALLIED CATALOG Phone: Tyler 8 -7129 AMATEUR RADIO LICENSES. COMPLETE THEORY The latest Allied Radio Corporation preparation for passing amateur radio examinations. Home study and resident courses. American Radio Institute. World wide finest and fastest service. List your catalog, No. 117, needs no introduction 101 West 63rd St., New York City. See our ad on Page 05. to most servicemen, amateurs, and ex- needs with us on all ham gear. All tubes are WE REPAIR ALL TYPES OF ELECTRICAL INSTRU- standard brands and guaranteed. Merchandise perimenters. It has 176 pages and con- ments, tube checkers and analyzers. Hazeltan Instrument Co. (Electric Meter Laboratory), 140 Liberty Street, New in original package. Minimum order $5.00. 25% tains complete listings of radio and York, N. Y. Telephone- BArclay 7 -9239. deposit required on all C O D orders. F O B electronic parts and equipment, tools, WANTED-5000 LBS. ALUMINUM FOIL ,00017 TO Detroit. Request our prices on receiving tubes. supplies, and books. 18-Any width. Good -All Condenser Co.. Ogallala, -Gratis Nebraska. 15E $1.50 954 8.50 955 .50 1 -2- INSTRUMENT CATALOG YOU CAN ACCURATELY ALIGN SUPERHETERODYNE 15R 1.50 receivers without signal generator. Complete instructions 1520 .50 958 .50 $1. Moneyback guarantee. Chas. Gates. Pecos 2, Texas. LOOR 1.00 957 .50 Bradshaw Instruments Co. issues a V R75 1.35 958 .50 four -page illustrated leaflet LANCASTER, VR90 1.35 959 .50 describing ALLWINE & ROMMEL. 436 BOWEN 1619 .50 Building, 5, V5105 1.35 Washington D.C. Registered Patent Attorneys. 1624 .60 the Range Master Models 10 and 10 -P Practice before United States Patent Office. Validity and V S150 1.30 HY114B 2.25 1625 .60 multimeters, Model 30 infringement Investigations and Opinions. Booklet and 1626 the multitester, form "Evidence of Conception" forwarded upon request. 2C26 .35 .60 and the Model 300 signal generator. 2021 1.80 1629 .60 - 2X2 1.35 1630 .60 MAGAZINES (BACK DATEDI- FOREIGN, DOMESTIC, .60 2050 .80 Gratis arts. Books, booklets, subscriptions, pin -ups, etc. Catalog, 2304 3B25 4.50 2051 .80 100 (refunded). Cicerone's, 863 First Ave., New York 7193 .30 17, N. Y. 3024 .80 J -3- ELECTRIC PLANT GUIDE 51(34 1.10 8005 2.95 6AK5 1.56 9001 TRANSFORMERS- 2 : A 20 85,000 VOLTS AT 30 MA. -350 6AK6 1.15 -page guide points out differ- Amp., 5 Volt jobs. Make offer. Bradshaw Instruments, 348 9003 .60 Livingston SL, Brooklyn 120A 1.25 ences between the a.c., d.c., and bat- 23, N. Y. IH2O .55 9004 .60 9005 .60 127A 3' tery- charging electric plants made by WANTED: USED SPRAYBERRY RADIO N.D. COURSE. 211 .95 9006 .60 D. & Box 192, Wray, Colo. 3D21A 7.50 C1(1006 .65 W. Onan Sons, Inc., and gives in- 10Y 1.95 1071 .35 .85 structions for choosing the proper type NEW CARTONEI) TUBES 39c. 1A5gt. 185, 155. IT4, 354, 3048 .95 SCOPE 3v4. 5Y3gt, BADS, OAKS, SAAB. 611A6, 613E6, 611116, 304TL .85 TUBES and size for any application. A.c. mod- 6B.16. 6C5gt 6J5gt. 6SA7gt. 6S1.47gt, 6V6gt. 6X4, 12AT8, 316A 1.50 2AP1 2.95 908 1 95 12BA8, 12BE8, 12A8gt. 25L6gt 32L7gt 35135. 35W4, 97, 323A .80 els supply from 300 to 35,000 watts at 5085, 70LTgt, 80, 117L7gt, 11723. Write for catalog. 350A .80 9LP7 1.50 all standard voltages Renshaw Radio, 3619 ')'roost, Kansas City, Missouri. 446A .80 5 CP1 1.50 and frequencies. 815861513 1.10 1.50 D.c. models deliver 750 to 15,000 watts 800 1.95 YOU CAN HAVE 28 YEARS RADIO EXPERIENCE AT 3.75 your fingertips. I've repaired over 45,000 radios. Have 801A 115 volts, and 2 to 15 kw 230 per- 802 1.95 at at volts. fected simple, easy system anyone can follow step by step. 803 3.95 0A2 $2.2013 Battery- charging plants deliver 30 to No calculations, no formulas. Total price, $2.00 postpaid or Money 805 3.75 0A3/VR75 1.35R C.O.D. -back guarantee, Roas Radio, 14615 -B Grand - 2.50 3,500 watts 6, 12, 32, and 110 volts river, Detroit 27, Michigan. 807 0B2 2.30 at 808 1.85 083/V1190 5.35R d.c.- Gratis 809 1.95 0C3/V11105 1.35 R LONG PLAYING RECORD TURNTABLES, 33% AND 78 810 4.95 003/V5I50 1.308 H.Y.M., take rr record. volume control. pickup input. 811 2.45 2C26A 7.75 J-4-CONVERTER CATALOG Modify these high quality precision made, units for use 812 3.50 2E25 5.50 with your record player. Regularly $49.50. Our price $4.99. 813 5.95 2E30 2.455 This 12 -page catalog lists specifica- Ask for bargain list Amplifier and Radio Parts, Magull'e, 814 4.95 384 3.60 68 West 48th Street, New York 19, New York. 816 2.95 104 1.95 tions of vibrator -type converters and 826 .95 864 1.75R power supplies made by Electronic Lab- NEWSFLASH from Radio Britain. PRACTICAL WIRE- 829B 3.75 1616 8.65R LESS, Britain's leading radio monthly, covers entire 832A 3.75 5514 4.95 oratories, Inc. Converters deliver 115 - British -European radio -television field. Latest advances 836 1.75 5516 5.95 "over there" detailed and explained by experts In every 837 1.75 E1148 2.25 volt, 60 -cycle a.c. from 6 -, 12 -, 32 -, and issue. Packed with new ideas and information essential to 838 1.75 HY24 1.50 110 DX "hams" listening to Europe, servicing experts and 860 2.50 HY35Z 5.50 -volt d.c. and from 115 -volt, 25- and all radio enthusiasts. For annual subscription (12 issue. 866A 1.95 HY69 5.50 50 -cycle sources. Power supplies deliver mailed direct to your address from London). send only $2.00 874 1.20 HY75A 4.70 to George Newne. Ltd. (PW /33), 342, Madison Avenue, 884 1.35 HY615 2.25 high -voltage d.c. from 6 -volt d.c., and New York 17. 876 1.25 HY12312 5.50 831A 2.95 11Y1289 5.50 6 or 12 volts d.c. from 115 -volt a.c. Re- 12B8 8e 2588 TUBES. ADAPTER UNIT USING 2 placement vibrators for converters, am- miniature tubes (BATS & 6BA6 for 12158, and 12ÁT6 & 1211A6 for 2588). Takes less space than original tube- THE HOUSE OF TUBES plifiers, and transmitters are listed. - nothing else to buy-lust plug to & It works. Money -back guarantee. 12B8 or 2588 unit complete: $1.49 each, 10 8748 Linwood Ave., Detroit 6, MIch.l Gratis units for $22.50. Send 25% deposit balance C.O.D. Write for tree parts catalog. COMMERCIAL RADIO, 36 Beattie 8 SL, Boston. Mass. Phone: TYler -7129 1-6-POWER SUPPLY BULLETIN L WANTED: APR -5A, APR -4 RECEIVERS AND TUNING J A 2 -page bulletin, issued by Electro Units, Antennae. Radar Scanners. VHF -SIIF Gear. Labo- E -Z TO ASSEMBLE! Products ratory and Test Equipment of all types. Also quantity stocks Laboratories, Inc., lists sev- of all types of surplus materials for marketing. Engineering eral types of A- and B- eliminators for Associates, F20111111 Branch Box 290, Dayton 9, Ohio. Save Money With This use with 1.4- and 2 -volt battery radios. PORTABLE SUITCASE SIZE RADIO SHOP. BUILD ltr, WAR SURPLUS They are available for operating from it and be ready for ready cash. Carry it In your car and double your income. Write, Grand Federal, Argentine Branch 6 -volt d.c. or 117 -volt 60 -cycle sources. Box 57C, Kansas City 3, Kansas. Aircraft A 6- or 12 -volt d.c. supply is also listed. PHOTO FLASH CRYSTAL SET -TELEPHONE COMBINATION DIA- -Gratis gram and instructions 25c. Includes attractive offer, liter- KIT! ature. year's membership In XTAL-X CRYSTAL SET I CLUB ", Box 608, Torrance, Calif. Offered at fraction of original Cot. J -6- PRIMER ON C -R TUBES Simple to a..enable. Save mane RADIOMEN, SERVICEMEN, REGINNEIIS - MAKE dollars. tomes brand n w In it. The Cathode -ray Tube and Typical more money. easily. quickly. $250 weekly possible. We original box complete with: gray Applications, by Instrument Division, how you how. Information free. Merit Products. 216-32L metal fini.bwt rease. all connectm. 132nd Avenue. Springfield Gardens 13, Nov York, relay control. each Allen B. Du Mont Labs., Inc., is 2000 volts-light output UM watt a 63- seconds, 4 HIGH SPEED FLASH page non -technical discussion of the "RADIO BUILDER" FOR CRYSTAL, 1 -TUBE EX- TUBES -plastic sealed. unbreak- perimcnten. 3 issues 25e. Laboratories, Eye -b, San Carlos, able. ALSO 4 reflectors. trans- cathode -ray tube and its functions. Sup- California. former, connectors, connecting ford.,. spare parts. After conver- plied with a wall- chart, the book is in- sion unit operates on flattery or on PHONOGRAPH RECORDS 20e. CATALOGUE, PARA - 110 volt A.C, by flick of switch. tended for schools and colleges. -Gratis mount, J -313 East Market, Wilkes- Barre, Penna. lomplete Instructions and dia- to teachers and instructors requesting grams. TELEPHONE DIALS, USED. NATIONALLY KNOWN Immediate Delivery on all mail orders on school stationery, 50c per copy to all make. Standard speed. 10 pulses per second. Ite -built $2.25. Complete Re- adlusted $125. postpaid. Kissel Electric Products, 431 -C f. 165 W 46th St . N. Y. 19, N. Y. De others Sherman, Gallon. Ohio. CINEX, INC., JANUARY, 1949 90 Miscellany ANSWERS TO QUIZ ON PAGE 37 1. If the control were open, there would be no d.c. path from grid of the tube to ground: the grid would block, and the set would squeal and motor- boat. If shorted, however, the grid would be at ground potential for audio. To check, touch the center lug with a screwdriver held in your bare hand. If nothing is heard, the grid is shorted to r V p namic SPee AM TV. y fM- ground, probably through a shorted Modern, problems, S -S. S tells HOW - in the Simple, and control or a lug touching the control's ing complexplotlearnpure hose simple, direct language. alignment ^ to case. N eou'pn` New 9th edition now off the press. No extra ment 2. Anywhere between 1 and 3 watts, - non-obsolescentEquip 100 pages of valuable information. Basic Test depending on the resistances. If the 2- Employs) only Available from all leading radio ports and watt resistor were twice as large as the equipment distributors or directly from factory 1 -watt unit, twice the voltage of the 1- at only 40c per copy. watt unit, and therefore twice the watt- age (P= E' would appear across it. Inc. 92 -27 Horace Harding Blvd., Elmhurst 4, N. Y. /R), PRECISION APPARATUS COMPANY, Then if this wattage were 2, the wat- tage across the smaller resistor would MORT'S NEW YEAR SPECIALS be 1, and total circuit dissipation would be 3 watts. If both resistors were equal, NEW HF 10 TRUSOUND AMPLIFIER A general purpose unit of small the same voltage would appear across Sise (0- 9- x 7) for high goal. ity prodluetlon of sound. music each, and each would have to dissipate speechpeeeh from records. microphone. Engineered and built the same power. Obviously, the maxi- to the high quality standards meet mum for each resistor would be 1 watt, usedd indconjunction withe tile nnew fidelity pickups. with total circuit dissipation of 2 watts. tuners a eaker sys- tems. NOTE THESE. FEATURES: R & M's GOT IT! To convince yourself, assign values to a * 10 Watts undistorted power output IS watts peak. * Inputs: Nigh gain for variable reluctance pickup.; pair of resistors and work out the cur- for high impedance mikes. Low gain 'for FM -AM NO MORE SEARCHING rent, voltages, and wattages. tuners and high output pickups. * Selector switch for rapid changeover. 3. In the parallel circuit the voltage * Hum level 70 db below 12 watts. FOR HARD -TO -GET * Tone compensation. Separate conti ly variable across both resistors is the same, but bne and treble controls. * Treble -from 10 db to minus 15 db at 10,000 cps. the current through each varies with * Sass -nom plus 10 db to minus 15 db at S0 cps. the resistance values. Again maximum * Note -oat characteristics obtained with controls SURPLUS Ocentered. dissipation is from 1 to 3 watts, de- * utput impedance 2, . S. 16 and 500 ohms. * Straight AC for 110.130V 50.50 cycles fused. pending on the resistances. * Tubes- -6SL7, 65C7. 2-6VS, 5V3. RADIO is * Chassis and shield silver grey hammerloid finish. 4. A practical temporary repair Complete with Tubes and Cover $29.95 EQUIPMENT shown in the diagram. Rl is 0.8 times SPECIAL LOW PRICE ON SPEAKERS 5" 1275 Ohm Field $1.79 ea. 1275 Ohm Fild a. Three large warehouses stocked with 3" PM with transformer... - Ì.5 ea. thousands of govt. surplus equip- MICRO GROOVE PHONO PLAYER ment and parts, priced at a frac- A NEW Record tion of original cost. RI R2 hundreds o'of bromcusldne` lation. in thPlayer.'SnU. S. Tile Trusound Microgroove Record Player Uses the new SHURE Featherweight and cartridge. Overall wt. 8 grams. of the micro.gmove h Write for complete price list. Indi- 9nÌ /3lRPM tante la ecor nimble, tm Inerfere With vidual data supplied on specific andrqu et it / oaW mWSOor equipment. the original volume control's resistance, List Prise 524.95 Your Cost in lets of 1.3.....9.50 ea. and R2 is 0.2 times the original. 513.95 ea. or More 5. the receiver is an a.c. model, re- 10 LS. SURPRISE PACKAGE If I Contalnin miscellaneous Radio P. rin. Condensers. RandM move tubes one by one, beginning with Hardware. etc. Easily worth more Lech the antenna end of the circuit. After SERS 1 FIFO Generator Codenser RADIO COMPANY each tube is removed, rotate the volume in Metal Can 22c ea... 10 for 52.00 Television Condenser control and note the change in back- .001. 8.000V 49e ea. loo for 545.00 .0005. 8.000V 49c ea. 100 for 545.00 ground noise it causes. When, after re- Write for Our Free 1949 Catalog. TERMS: Minimum order $3.00. 25e/e deposit. moving a particular tube, rotating the Bal. C.O.D.. F.O.B. Chicago control has no effect on the noise, you can assume that the control was in the Mort's Radio Shack circuit of the tube just removed. Dept. RC -IA In an a.c.-d.c. set, removing a tube St., Chicago 6, Illinois 630 W. Randolph 1426 N. Quincy St., Dept. F, Arlington, Va. opens the filament string. However, if you rotate the volume control before NEW PRINTED LEARN the filaments have a chance to cool down, you will still hear the change FUN cRCIJITS PROFIT in noise. Of course, you must replace DESIGN -REPAIRRESEARCH each tube and give the heaters time to Now Faster and Easier warm up again before pulling out the Be first to learn the new printed -circuit methods. Most new radios have partly printed circuits. Paint next. WORKING circuits over your sketches. Kits of con- WIRE ductor and resistance paints: Standard 53. Super ó5 LITZ (has sliver Ink). Instructions. Valuable for colleges. Radar for locating icebergs was used Free descriptive literature. Just send cash or M. O. and note with name. address and desired kit to: Magnet Wire last summer by ships of the U. S. Coast MICROCIRCUITS CO. Guard. Since the international service Dept. 2D New RMMale. Mkhi as LARGE STOCK for detection of icebergs, derelicts, and Radio courses are the most popular of * * other obstructions was set up in 1914, all studies among veterans taking cor- MAGNET WIRE, Incorporated operations from both ships and aircraft respondence training under the GI Bill, have often been hampered by fog. The the Veterans' Administration reported 25 WEST BROADWAY radar penetrates fog. A standard radar recently. Twenty -six percent of the vet- Worth 4 -5447, Beekman 3 -8465 scope shows the icebergs as pips on the eran students are enrolled in radio and Cable Address: "Magnetwire, New York- screen and their exact locations are other communication courses. worked out with the aid of loran. RADIO- ELECTRONICS for Miscellany 91 sabio Tfjírtp-lfíbe Pearl ago iltt Ocrn.9barb Vuhlicatíong HUGO GERNSBACK LET THIS "AUTOMATIC TEACHER" Founder Modern Electries 1908 show you exactly how to repair over Electrical Experimenter 1913 Radio News 1919 Science & Invention 1920 Radio -Craft 1929, Short-Wave Craft 1930 Wireless Association of America.... 1908 4800 RADIO MODELS Some of the larger libraries in the country still hay copies of ELECTRICAL EXPERIMENTER on Pie for interested readers. without expensive test .equipment ! In ELECTRICAL EXPERIMENTER January, 1915 GHIRARDI SAVES YOU TIME Wireless Telegraphy from Airplanes Short-Wave Receiving Loose Coupler -HELPS YOU MAKE MONEY Ghirardi's RADIO TROUBLESHOOTER'S Aerial Insulators HANDBOOK is the ideal manual to show you Mounting Detector Crystals, by Ralph exactly how to repair radios at home in spare tins-- quickly and without a lot of previous ex- E. Brooks perience ar costly test equipment. It contains Hy -Tone Radio Test Buzzer MORE 'THAN 4 POUNDS OF FACTUAL. time -savig, money- making repair data for re- High Tension Aerial Switch by John pairing all models and makes of radios better, Chambers faster and more profitably than you may have A Synchronous Rotary Spark Gap for 'thought Possible! Small Coils, by Earl Emendorfer NOT A "STUDY" BOOK RADIO TROUBLESHOOTER'S HANDBOOK An Acoustic Radio Amplifier can easily paY for itself the first time you use it. The E. I. Co. Laboratory at New York You don have to study it. Simply look up the make, model, and trouble symptom of the Radio Long Distance Radio Receiving you want to repair and go to work. No lost time! 110 Volt Transmitting Set on Batteries Clear instructions tell exactly what the trouble is likely to be- EXACTLY how to fix it. Act -ally, this big 714 -page manual -size HANDBOOK brings you factual, specific repair data for the common troubles that occur in practically every radio in use today -for over 4800 Popular models of Home and Auto radio receivers and Automatic record changers cal 202 manufacturers! In addition, there are hundreds of pages of helpful repair che:rts, tube charte. data on tuning alignment, transformer trouhles, tubes and parts substitution, etc., etc. - all for ordy E6 ($5.50 foreign). Read it for 10 Lt coupon. days ... our risk! Use 741 manual -size Dagea Get a Complete RADIO- ELECTRONIC SERVICE EDUCATION NEW SUPER -CLIP -BOARD King of all clip- boards is this "Electronic Circuit Panel" developed recently by Kepco COMPLETE DATA ON TEST INSTRUMENTS Laboratories. It substitutes push -down binding posts for the clips, and circuits are printed -TROUBLESHOOTING -REPAIR on sheets with holes which fit over the posts. A. A. Ghirardi's big 1000 -page ment types ; how thoy work (with Thus it it necessary only to wire directly over MODERN It '1.1310 SERVIC- wiring diagrams), when and why the line below to follow the circuit. The 23 ING is the finest, most com- to use them; how to build your book own; circuit charts cover a wide range of circuits, plete instruction on Ra- preliminary trouble checks; dio- Electronic service work for circuit and parts analysis ; parts from diode detectors to scale -of -two counters. either the novice or the profes- repair, replacement, substitution; Blank sheets are also provided for the stu- sional Radio -Electronic service- obscure radio troubles ; aligning dents' own circuits. Rear wiring shown below. man -bar none! Read from the and neutralizir g; int. rference re- beginning, it is a COMPLETE duction and hunt reds of other COURSE IN SERVICING by subjects -incluefng How to Start the most modern methods. Used and Operate a Successful Radio for reference, it is an invalu- Electronic Service Business. 723 1300 pages. 706 illus. able means of brushing up on self -testing review questions help 723 review questions any servicing problem. you check your progress EVERY Gives complete information STEP OF THE 'WAY. Only 35 on all essential service instru- complete 35.50 foreign). FREE You Can't Go Wrong on a 10 DAYS' EXAMINATION Ghlrardl Radio Book Technical Division, MURRAY HILL BOOKS, INC. Dept. RC -19, 232 Madison Ave., New York 16, N. Y. Send me the books checked below for 10 days examination on approval. In 10 days I will pay for the books plus a few cents postage, or return them postpaid. (Postage paid on rash orders; same return privilege. Books sent on approval in U. S. only.) Q MODERN RADIO Q RADIO TROUBLE- SF.RVICING SHOOTERS HANDBOOK 35 155.50 foreign) $5 (35.50 foreign) Q Special MONEY-SAVING COMBINATION Both big books for only $9.50 (310.50 foreign) MONEY- SAYING Name OFFER! Get BOTH big books - Radio's most fa- Address mous Service Library - over 2030 pages a City & Dist. No State - at (Please print or write plainly) bargain combination price. See coupon. JANUARY, 1949 Miscellany 92 ( RADAR TELESCOPE ONLY $99.50 IS THE COST! GET YOUR E/Co Radio astronomy will be studied at Cornell University with a new radio TEST INSTRUMENT KITS telescope, the university announced last from month. The telescope, completion of GREEN which is expected in a few months, will HIGH PRECISION consist of a 17 -foot parabolic reflector with a small antenna at the focal point. VACUUM TUBE Sensitive receivers will record extra- VOLTME TER terrestrial r.f. noise. This is the first Model 2 @ o instrument of its capabilities built espe- Complefe2 Kit $23.95 noise. The tele- THE MOST USEFUL TOOL _ cially to study cosmic ON YOUR RAD10 BENCH! scope described last March was a con- D.C. and A.C. ranges 0 -5. 10, .. . lip 100. 500. and 1000 colts. . , verted Wurzburg radar antenna. Ohmeter ranges train .2 ohm ^_ to 1.000 megohms In steps of ..t4) O 11x1. Rx10. Itx1000. 11x10,000 for the SENSATIONAL -NEW- IMPROVED and Rai megohm. Db scale from -20 to 55 Db In 5 ranges. D.C. Input resistance is 25 megohms. A.C. Input Impedance Is over PA 10 INCH megohms. Diodo A.C. rectifier for greater accuracy and wider frequency range to 30 Kc. Large. rugged. 4%" meter with all A.C. and D.C. readings on one simple scale. All multiplier resistors matched to 15b accuracy. KIT Complete with 6H6. 6X5, 66N7 tubes and test prods. TELEVISION All numbers etched Into panel: can never rub off. Heavy Complete with new built -in pretuned and gauge steel cabinet. Size: 9 -7/16' x 8" x 5'. Shipping WL 10 lbs. NOTHING ELSE TO BUY! aligned 13 Channel tuner, all parts and easy step -by -step Instructions and schematics. Model P -75 germanium crystal probe for glutei RE signal tracing. and measurements to over 200 mega $99.50 Is tubes cycles $7.50 Kit, complete with all tubes $149.50 ASSEMBLED VTVM Specially designed cabinet for kit 25.00 Model 221- Includes all advantages of above. Com- assembled. hand calibrated and tested and one pletolY An amazing value! Even a beginner can assemble ready to use. at the amazingly lose of these fine. new Improved television kits. Uses the price of $49.95.Des s7 Js7 new 13 channel tuner, prewirod and factory aligned for the entire television spectrum. High quality pans and excellent circuit assura perfect performance. Cir- POCKET cuit designed by outstanding T.V. engineers. Contains RF stage. oscillator and mixer. Uses new I.F. coils 3s VOLT -OHM providing maximum gain and picture definition. Sound reception is high quality FM for years of listening MILLIAM- pleasure. ¡lei Same quality and featares for 7° KIT complete. M ETER COM- lass tubes. $59.50 Complete. with tubes .. 99.50 PLETE KIT Specially designed cabinet for 7° kit 2250 Model 511 -K A This kit can be used with Sylvania 10 HP4 tO" pie. "MUST" FOR tore tube without modifications. EVERY SERVICE- 7- and 10° KITS AVAILABLE FOR IMMEDIATE MAN! The small. DELIVERY FROM STOCK! handy instrument that every repairman uses a thousand times a day. Large 3" meter, beautiful etched panel. Simple to as- aemblo. A PERFECT KIT FOR BEGINNERS. Ranges. DC -0/5/50/250/500/2500 v-1ts. AC -0/10/100/500 /1000 The New volts. Output -0/10//100 /000 /1000 volts. Dl' Ma. Model B -45 -0/1 /10. DC Amps. -0/1 /10. Ohmmeter -0/500 /100.000 New radar telescope at Cornell University. Battery ohms /0 /1 meg. Db meter -8 to 55 Operated Db $14.95 ASSEMBLED -READY TO USE The analogy between the radio tele- SIGNAL Model 511- Completely wired, tested and assembled at the factory. Rugged, built for heavy scope and a standard optical telescope GENERATOR duty $17.95 is very close. Both are used to detect for servicing AM. electro- magnetic radiations. The optical FM and Television OSCILLOSCOPE telescope receives radiations in the vis- Receivers. H.F. fre- KIT quencies from 150 ible which includes a band of Kilocycles to 50 Model 400 -K Indispensable range, Megacycles (150 Kc. for AM, FM, and TELEVI- frequencies about one decade wide, that to 12.5 Mc. on Fun- SION. sweep cir- Meals and from cuit 151t. to irontu cycles. All C is, with a 10 to 1 ratio between the Il Mc. to 50 Mc. on harmonica). C ploc with controls on front panel lowest frequencies. The - highest and shielded test lead. self -contained bat $27 75 Lines sweep with 884 gas tcries and Instruct Ions. NET -P triode. Graph screen for radio telescope receives frequencies be- ale. req peak to volt- 1 age. . Ftal anmv ricalresponse of tween 20 and 30,000 mc. Cerafrom and vertical The New Model TC50 from cycles to 50 Kc. Cosmic noise or static in the r.f. ,rte .i Inputandut impedanceImpedance 1 megohm in TUBE and 50 mmfd. Etched panel b,- 6 range originates at certain places - - a. i for Ionic life. Tube compte b the universe and has certain frequen- AND SET ment: 2 -8577. 2 -5n3. 1 -884. . crlelon for ex- cies at each place. The parabolic an- TESTER ternal syncDeflecattnn teat voltage and In ensity modulation. Deflection .65 volts per In h full tenna is very sharply beamed and polar- gain. Detailed Inalructlonsinstructions and pictorialpi diagrams In- A complete laboratory x1 ELSE TO BUY! ized. It will scan areas of the sky with . 1 all purpose teat -in- Sieot:d81/2'W 13 "H D. Shoe wt of 2 to 30 degrees, depending 0 strument, this versa 40 lbs $39.45 diameters Me combination tube on frequency. It will be rotatable in and set tester will ac- COMPLETELY FACTORY WIRED 4,1 ' a curately test all up- several directions, as well as turning to -date designed tubes. OSCILLOSCOPE p The multi -meter sec Model 400 -Same as above but wired, tested and as- on its own axis to vary polarization. thon affords many sembled. A sturdy well -designed Instrument. ready to necessary mesure use ort your work bench. Don't sealz. Receivers for 50, 200, 1400, and 3000 $69.95VJ s7 meets for everyday's order NOW! mc are being assembled. Through the service work. The New Model TC -50 Tube nd Set Tester com- comparatively new medium of radio bines seven instrumente, D.C.V.. A.C.V., D.C.M.A., SENSATIONAL PRICE REDUCTION! Ohms. Output Meter. Decibel Meter and Tube Tester. Model 113 -A MULTI- ANALYST astronomy Cornell hopes to discover Full scalo accuracy to 2%. English Reading GOOD NOW much new and enlightening information and BAD scale for testing tubes. Obsolescence reduced FIRST TIMES $69.95 to absolute minimum. Simple and quick reading charts about the structure of the universe. for tubo testing. Multimeter section affords most pop- A Complete VTVM that follows signal from antenna ular everyday's measurements. to speaker! Extremely sensitive wide range AUDIBLE Model TC -50 Tube and Set Teeter operates on 90 -120 signal tracer. G tubes -gain over 90 In probe alone! Volts 60 cycles A.C. Housed In a sturdy beautiful Limited quantity-order NOW! Television may be used for teaching portable. hand -rubbed cabinet. Complete with tent leads. tubo charts and all detailed. operating in- 20% Deposit required trilh 0. 0. 0. Orders. All orders deaf children as the result of experi- structions. F.0. B. A e,eYork. All orders must Include shipping chows. Size 8" x 10',4- z NET $3950 ments conducted by RCA and Dicto- IMMEDIATE DELIVERY FROM STOCK THE HOUSE OF BARGAINS graph. Group hearing aids will be tied All orders tilled same day received into the sound channel of the receiver. GREEN RADIO DISTRIBUTORS A demonstration of the new technique 9tmpJAipolL1an ELECTRONIC & was given last month in Detroit at the INSTRUMENT CO. Electronic Supplies and Equipment convention of Teachers of Deaf Chil- 482 Sutter Ave nue DI 2.4444, Brooynkl 7, N. Y. RC-1 12 WARREN ST. N. Y. 7, N. Y. dren, a national organization. RADIO -ELECTRONICS for Communications 193 LIKES NEW R -E FORMAT SENSATIONAL RADIONIC OFFER ' Dear Editor: As a faithful reader of your maga- TUBES 32c zine for the past 10 years, I think you in bulk, lots of 100 per type have set the pace for magazines. I've Free! Individually it's always longed for one which had all White Boxed, asst'd 36c each the items on successive pages. Thanks Made by leading manufacturer - unbranded. RMA guarantee. Money back, less postage, if to you, a feature may be read without not completely satisfied. THOUSANDS OF SAT- thumbing through the whole magazine. ISFIED BUYERS! IRS 6B8G 6SK7GT 12SJ7GT Your new name surely expresses the 155 6C8G 6S8GT 125K7GT NEW contents of the magazine and in my 1T4 6K5GT 6V6GT 32L7GT 1U5 6K6GT 6X5GT 35W4 opinion could not have been better. 394 6SA7GT 12AT6 5085 1949 WALDEN MCKIM, 3S4 6SD7GT 12BA6 117L7GT 6AT6 6SF5GT 128E6 117Z3 EDITION Bessemer, Ala. 68A6 6SG7GT 12SA7GT 68E6 RCA GE SYLVANIA NATIONAL our LANGHAM HAS A FAN UNION KEN -RAD HYTRON 29th year Dear Editor: TUNGSOL RAYTHEON Type Packed in bulk Individually white How about a few more articles like 100 per type boxed - assorted those by James R. Langham? I think an 5Y3GT 400 490 6F6GT 550 69e article written in story form with a bit 6SN7GT 750 850 of humor is very informative as well as 12S97GT 550 650 25L6GT 650 750 being amusing. Of course I don't mean 25Z5 550 650 THE MOST FAMOUS that all articles should be written that 25Z6GT 550 650 way! 3516G7 650 750 35Z5GT 450 550 TIME AND MONEY SAVER I regard the Technote Section very 5OL6GT 650 750 highly, as well as articles such as W. G. Above 10 types show manufacturer's brands. Ship- ment will be made of makes available when IN Eslick's "Time- Saving Repair Tips" order is received. STANDARD RMA GUARAN- RADIO-ELECTRONICS! (July, 1948). The magazine has pro- TEE APPLIES Specify price when ordering ... l vided me with much of my radio educa- What other types can you use -bulk pocked - tion and I hope it will continue to do so 100 to a carton. LET US QUOTE! BIG 180 -PAGE Minimum order 53.00. 20% deposit. balance in the future. C.O.D. BERT DE KAT, Send for Free Bargain Bulletins LAFAYETTE-CONCORD Minburn, Canada - RADIONIC EQUIPMENT COMPANY CATALOG Tribune Theater Entrance This great 180 -page buying guide pays 170A Nassau Street. N. Y. C. 7 you dividends R -E INTERPRETS SCIENCE WOrth 2-0421 on every order you send to Lafayette- Concord. Look: Open daily 9 -6 :: Saturday 9 -5 Dear Editor: 1. GREATEST VALUES Your article describing the transistor You get the lowest prices in the industry, because you deal in the September issue was with the biggest radio supply organisation in the world! of great Lafayette buys in huge quantities, and the savings are interest to me. JANUARY VALUES passed along to you. You lop off a quarter, a buck or two on A private most every buy. That kind of money adds up, mieter. experimenter of limited Lafayette reliability is an old story to 500,000 satisfied formal education, I sometimes find such 3 TUBE PHONO customers ...So why take chances on unknowns? Trade periodicals as the Journal of Applied AMPLIFIER ii ii with Lafayette where you'll be sure of a square deal. Physics, Physical Review, and so on, 2. MOST COMPLETE STOCKS hard to understand. RADIO -ELECTRONICS s r You name it; we have it if anybody does ... in the house, all has become a sort of interpreter for 1.95 ready to ship! Headquarters for hi -fi, TV, P.A., testing translating scientific literature into equipment, parts, tools, kits. You can one-stop -shop for all the COMPLETELY WIRED, the famous brands in radio. Also, thousands and thousands little fellow's language. VOLUME and TONE CONTROLS of hard-to-find parts ... the kind that can drive you crazy if you don't know just where to lay your hands on them! Keep up the good work! Set of 3 tubes; 50L6, 3525, 12SQ7 $1.25 HERMON OutpuI trans. 50L6 .35 E. COTTER, 1¢ Meg- vol. control .15 3. FASTEST DELIVERY !k Meg. vol. control with sw .35 Detroit, Mich. AB dual control 200M ohm .69 You order from the nearest of our three great mail order 4' pen speaker .95 centers: Chicago, New York, Atlanta. Each center keeps 5" pm speaker 1.15 large catalog stocka on hand, to give you same -day service on 6" pm speaker 1.55 your orders! Or you can shop in person at any of our outlets DOWN WITH NOISE! 6x4" pm speaker 1.39 8" pm speaker 2.49 in S cities. Figure out how much this set -up saves you in time Webster pickups 1.79 and shipping costs! Dear Editor: Asiatic Cartridges L -70A, L -26A 1.49 Now you can ne why veteran radio mat feet positively naked .Alliance motor & Turntable 2.50 to copy I agree with Mr. Ward (Communica- G.E. Reluctance Cartridge 4.54 without of the Lafayette- Concord catalog around the tions, November) that ignition noise Phono Pre- Ampl!Ber complete with tubes 4.95 shop or shack! if you don't have it, shoot the coupon to us on Phono Oscillator complete with tubes 4.52 a penny postcard. We'll see to it that yon get one fast! must go, and the sooner the better. But Oscillator Coil, 12SÁ7 .15 PM ..C400 INTERMIX CHANGER IN NEW YORK - 100 Sixth Awn. 542 East Fortnum seed let's not stop with ignition noise -let's Automatic Stop -Special Price $19.95 IN CHICAGO 901 W. Jackson Blvd. 220 Waal Madison SP., SEABURG 3 POST INTERMIX CHANGER - go further and eliminate all man -made IN SOSTON 110 Federal Onto Aut ems. tic Stop 527.50 - IN NEWARK - 24 Central Awn. static! We should have little trouble Slow speed motor and TT 3.89 IN ATLANTA - 265 P..hlree Stn. Slow speed pickup with QT cartridge 3.89 dealing with radio interference now F.P. cond.. 4 section, 10 MFD -400V .39 I F transformers 456KC that there are plenty of spark -plug sup- Input or output, ea .39 pressors and power -line filters on the All prices F.O.B. N.Y.C. -on C.O.D. 25q'o Deposit. market. Write for latest circular LAFAYETTE- CONCORD I HE 1401, (l'. I P,^,E5! 1)4111)1 Slll'l'IY CnMI'l.'.- As Mr. Boehnke said (same issue), THE ROSE COMPANY an interfering amateur gets into plenty LAFAYETTE- CONCORD, Dept. JA-9 98 Park Place, Dept. C, New York 7, N. Y. RUSH!! of trouble; at the same time we have 100 Sixth Ave., New York 13 to put up with noise caused by some 901 W. Jackson Blvd., Chicago 7 FOR defective household appliance. 265 Peachtree St., Atlanta 3 Interference makes things even hard- a TINY RADIO! FREE ' 1sß. t Red plastic c ,e No tunes. Please send FREE catalog No. 89 er for us in Alaska than for you in the I /i .1 batteries or ctric plug- -PAGE ¡ .1st Ins needed! auaran- 180 States. We rely on short -wave reception \ - teed to receive local stations. Only $3.0)1 CATALOG eke tin ash) là NAME_...... - ...... - ..r....- ...._. 1 a for the programs you hear from your . I I-.i erl n nIY 51.000 e local station. - Pay 62.00 Complete PASTE ON e plyC.0.13, e e tlon. With Personal" phone. FLOYD P. BROWN, JR., Get your tiny radio now! Sitka, Alaska MIDWAY SALES CO.. DEPT. Tic-1.. KEARNEY. NEBR. CITY . ZONE STATE ===s'====POSTCARD JANUARY, 1949 94 RADIO SCHOOL -s i DIRECTORY WANTED Men and Women fo Fill TOP RADIO JOBS S P E C I A L I Z E S P E C I A L I Z E in AM- FM- Television If you are looking for a career with a future. why not join the Martin School loflRa diodArts now dsuccessfully employed In the radio industry. The demand Is great for qualified radio personnel in AM- F31- Television. Train now to be an announcer, script writer. disk jockey. news- caster. or radio technician. Complete day and night classes the latest equipment. Free placement service. Approved for veterans. Write for free booklet. Don Martin School of Radio Arts 1655 North Cherokee St. Hollywood 28. Calif. IREVISION ¡EC NICAL CAREER As Television gains momentum, rapidly, constantly, It offers to properly-trained tech- nicians careers with a future in Industry, Broadcasting or own Business. can become a Radio and Train at an Institute that pioneered You in TELEVISION TRAINING since 1938. Morning, Afternoon or Evening Sessions in Technician now! laboratory and theoretical instruction, un- Television covering all phases der guidance of experts, of Radio, Frequency Modulation. Tele- 4,000 a week will he created in the A million new jobs - almost - vision. Licensed by N. Y. State. Free television industry during the next five years according to estimates of Placement Seri lee. Approved for Veterans. Actually, during 1948, television grew faster than ENROLL NOW FOR NEW CLASSES industry leaders. Visit, Write or Phone any other industry in the history of America. Here is a real opportunity for you. Trained television technicians are RADIO- TELEVISION in demand. By starting now, you can get in on the ground floor - grow as television grows. INSTITUTE the Milwaukee School of Engi- 480 Lexington Ave., N.Y. 17 (46th St.) To help supply this needed manpower, Plaza 3 -4585 2 blocks from Grand Central neering has expanded its radio and television courses. Now you can get complete practical, technical training in the MSOE laboratories. This is not just a serviceman's course. It prepares you for a career in all of the technical phases of television and radio. This special course Prepares you for any of the following ca Rail - RADIO Television Serviceman Supervisor in Radice and Police, Taxi-Cab and Radio Serviceman Television Assembly road Transmitter Operator Radio and Television Radio and Television Tester Police, Taxi -Cab and Rail - COURSES Retailer Broadcast Radio -Operator road Receiver Serviceman Preparatory, Service, Broad- OTHER COURSES AVAILABLE cast, Television, Marine Op- Fre- SERVICE TECHNICIAN PROFESSIONAL erating, Aeronautical, 6 to 12 Months 1 to 2 Years 3 Years quency Modulation, Radar. Electricity Electrotechnics Electrical Engineering Classes now forming for mid -year term Feb. ist Welding Radio and Television Bachelor of Science Electronics Degree Entrance exam. Jan. 17 Refrigeration Refrigeration, Healing and Air Major in Electronics Veterans. Literature. Heating Conditioning or Power COMMERCIAL RADIO INSTITUTE (Founded 1920) *---MILWAU(f 38 West Biddle Street. Baltimore I, Md. 5CHML of ENGINEERING a Technical SCHOOL Institute SOUND RECORDING Fended 1903 A practical engineering course in Sound Fundamental,. Recording, and Sound Transmission measurements; In sets. oscillators, by Ds M Wealth a laboratory containing transmission square wave generator and intermodulation analyzer. and :4 1 - -p Cher equipment. Complete recording studio assimilating broadcast, motion picture and commercial sound recording. under the direction of H. M. Tremaine. MILWAUKEE SCHOOL OF ENGINEERING, -' Dept. RE -I49 HOLLYWOOD SOUND INSTITUTE, Inc. N. Broadway and E. State Milwaukee, Wis. 1040 -C No. Kenmore Hollywood 27, Calif. Without obligation send me free booklet "Career Building" and more details on course in Radio and Television or course. Name Age RADIO COURSES RADIO OPERATING CODE Address RADIO SERVICING ELECTRONICS City State F.M. TELEVISION I_ REFRIGERATION SERVICING Write for Catalog and Picture Brochure Y.M.C.A. TRADE 8 TECHNICAL SCHOOLS 15 W. 63rd St. (N'r B'way) New York City LEARN RADIO! IN ONLY 10 MONTHS RADIO and TELEVISION PREPARE FOR A GOOD JOB! Complete Radio Engineering COMMERCIAL OPERATOR (CODE) Course. Bachelor of Science De- Thorough Training in All BROADCAST ENGINEER gree. Courses also in Civil, Elec- Technical Phases RADIO SERVICEMAN trical. Mechanical, Chemical, Aeronautical Engi- APPROVED FOR VETERANS DAYS-EVENINGS WEEKLY RATES Television Servicing -15 Months neering: Business Administration, Accounting. Secretarial Science. Graduates successful. 66th RCA GRADUATES ARE IN DEMAND Veterans get $130.00 Equipment year Enter Jan., March, June, Sept. Write for For Free Catalog Write Dept. RC -49 SEND FOR FREE LITERATURE catalog. RCA INSTITUTES, Inc. TECHNICAL INSTITUTE A Service of Radio Corporation of America BALTIMORE AeaiGOLLA ö11ë INDIANA 1425 Eutaw Place, Dept. C, Baltimore 17, Md. TRI -STATE COLLEGE 350 WEST 4TH STREET NEW YORK le. N. Y. RADIO -ELECTRONICS for Communications 95 ELECTRIC SHAVERS INTERFERE WITH FM? Dear Editor: on razor interference is evidence of how AU RAI;/0 PECEPT/ON The letters on FM interference you subservient it is to commercial inter- \TO Llee, have published during past months have ests? (Aren't motor cars also objects i"0 & /r//1(.ß('..'1 left me puzzled as to why the powerful of commerce ?-Editor.) buzz -saw interference of electric razors I'd like to see what the neighbor's eludes not only the execration it de- beard does to television -but not in my serves, but even mention. Razor inter- living room. The ruination of music is ference is an even greater evil than bad enough, thank you! ignition noise. Why is the lesser evil C. P. BROCKETT, A featherweight unit that gives greatly in- -dwelt on to the exclusion of the greater? Ajax, Ontario creased signal pickup when attoched to any typo whip car aerial. Attached instantly -ad - I could name a Scandinavian country ¡astable for any angle -will not wind -whip- where everything likely to create inter- (In our experience, a genuine FM set highly decorative -not- rusting, allows use of ference rod in telescoped position or extended- must by law be quieted. Laws -not a wide -band, high- frequency AM I greater volume -greater distance. like this will have to be passed here set -gives practically no evidence of an The Signal Soc is the most unusual auto radio some day meantime, what primitive electric shaver, even . item to appear on the market in the past ten ... brought close to years. chaos ! the antenna lead. Have other readers Available in Red, Blue, Green, or natural I wonder if the silence of the press had shaver trouble ? -Editor) anodized aluminum finish. List price $2.00 Your Cost $1.20 WANTS MORE COMMER CIAL AUDIO CIRCUITS Dear Editor: body, Specify colon wanted Check with order. Postpaid In U.S.A. and I think everybody should be Robber inmates ...oiled.) May I take this opportunity to say I well satisfied. WORLD. IN COLOR PRODUCTIONS like your new title, style, and layout Your latest Audio -Sound issue was, los W. dumb U. ElaJea. N, Y, very much? I am an audio fan, and I of course, especially interesting to me. wish to thank you for the very fair way Could we have a few more circuits like you allocate space to the different de- the Langevin 122 amplifier? They keep partments. My friends and I all think us up on modern practice. it is the most interesting of the many H. G. WARREN, publications we get. You cater to every- Luton, England RADIO- ELECTRONICS GREE TS RADIO- ELECTRONICS Specials in Condensers Dear Editor: boon to our 5 Mfd. 35V Tubular 10 for $1.25 technicians. 10 Mfd. 150V " 10 for $1.95 Congratulations! We, too, feel that You and we both arrived at the same 20 Mfd. 150V " 10 for $2.25 RADIO-ELECTRONICS the name more ade- name, but by different routes; we 8 Mfd. 400V " 10 for $2.95 quately describes the material in your through imagination and nerve -and a 8 -8 Mfd. 450V " 10 for $4.95 excellent magazine. Every month we little money; you through years of hard 2" Round G.E. 0 -I R.F. Meter $1.95 look forward to our copy. work and of literally growing up with Write for Bulletin No. C -914 Veterans who started our own radio the industry. XSOUND EQUIPMENT Co. and appliance business, we have many Keep up the good work! 911 -913 Jefferson Ave TOLEDO 2,01110 reasons for praising your magazine. J. M. BURDETT, The help we have received from your RADIO- ELECTRONICS, many diversified articles has been a Kapuskasing, Ontario Get Started in Radio 10 "HOWTO1)0IT" BOOKS LONG BEACH, CALIF., W ILL HAVE PORT RADAR Get n solid foundation In radio by of these 10e timely text books. Dear Editor: tween the ports of Long Beach Each' clearly written, profusely iOus- and trated, contains over 15,000 words. We appreciate your inquiry Los You'll be amused at the wealth of regard- Angeles even though they are Information into these °Excellent `for ing the installation by us of a port located in the same geographical area; for technical library. Your money radar. Our Board of Harbor Commis- this radar is being considered for Long bark if not satisfied. sioners is giving final consideration Beach. At the present time we are the 5 BOOKS for 50c . to the installation on our pier of fourth largest producer of oil in the 10 BOOKS for $1.00 a pilot such station for radar equip- state of California with an annual in- Sent to You Postpaid ment. come from oil of approximately $30 Noe tionary (Leading Terms) Incidentally, you committed a grave million per year. Therefore we prefer l Sto°vFourShort No. 6-Ho To Have Fun No. With Radio error in stating, "that you plan the that a distinction be made between Moat Popular Alll-h Wave l No. 7 -Now To Read Radio the and 2 Tube Receivers Diagrams construction of a port radar Los two ports. NO. Currant for -eil te ersing No. fie- Simple Elecctricai Ex- Angeles." A. MADDY, No. 4-All About Aerials periments There is a keen rivalry be- K. No. a- Beginnen Radio Pic- N 10-Television Executive - Secretary. Remit by check or order -register letter It you Board of Harbor Commissioners, send cash or stamps. Long Beach. Calif. RADIO PUBLICATIONS 25A West Bwey. New York (7) (RADIO- ELECTRONICS desires to apolo- Lea he Telegraph Remo ed. nten l'htuThousands Ceres of gize for its error, and wishes the port of men "ode IntenselyLearn interesting work-good naa.pay. Learn at ho as o Long Beach every success in its struggle wherever you are. easily. Pill BROOK DU the far for its proper place in the System. Qualify for amateur or commercial license. Books sun. Latest $3.00 n FOR CARTOON IDEAS report, incidentally, says contract has - CANDLER SYSTEM CO. RADIO -(RAFT prints several radio car- Dept. S -A, Box 928 Denver I, Colo. been let and work is about to start.- toons every month. Readers are invited Editor) to contribute humorous radio ideas which can be used in cartoon form. It CORRESPONDENCE COURSES IN is not necessary that you draw -a sketch, unless you wish. . RADIO and ELECTRICAL ENGINEERING RADIO IDEAS NOT WANTED No ELECTRICAL ENGINEERING ;r, TECHNICIAN and RADIO SERVICE COURSES electrical or radio definitions wanted. Prepare yourself at Low Cost, for enure future. Mulero Some of these were published in the ti" simplified anyone can understand mnrkly, FM and TELEVISION past, but the subject is about exhausted. n r ^° fir In rad' ^ RADIO ENGINEERING All checks are payable on publication. urk. Trains you to be su,Vg,ererviced mam vacuum. AMERICAN RADIO INSTITUTE t i fan. aer+lremen needed badly. Diploma on Address: 101 r,lstiun. Many graduates earning big pay. 11 West 63rd St., New York 23. New York Free Colle. RADIO CARTOONS, RADIO -CRAFT school 4 "ro Either Approved Under GI Bill of Rights 25 West Broadway, New York 7, N. Y. WRITE ab, mt deferre ' co-. ent`plan. :rit! $25 Coursa Seta, co-. Licensed by New York State Lincoln Engineeringg i:ean -Wool, 871C1311. Linwln 2, Nab. JANUARY, 1949 90 sex* FREE&tedoq CanM'latch these Index to Advertisers You Adson Radio Company 74 Allied Radio Corporation 55 /CSI !/a/uese! Almo Radio Company 69 /1N-I/1fliP American Phenolic 61 Amplifier Corp. of America 71, 85 Electronic Lab Arrow Electronics 70 MIDWEST Associated 68 Mofle! 2606 Radio Distributors Bargain Radio 85 PORTA-POWER Bell Telephone Laboratories, Inc. Back Cover RADIOS Ready for immediate installation Brooks Radio Distributing Co. 82 to operate mobile transmitters, Buffalo Radio Supply 58, 59 receivers, public address systems, Burstein -Applebee Company 80 etc. Requires only 6 VDC input; sup- Capitol Radio Engineering Institute 6, 8 plies 300 VDC at 100 MA under load. Cines, Inc. 89 Powerful Cleveland Institute of Radio 20 ONLY Hum -free output. Trim metal case with bumper feet; measures only Communications Equipment Company 77 5":51/4"041/4". Complete with 6X5 Coyne Electrical School 80. 86 tube. Nothing else to buy. Regular DeForest's Training, Inc. II $11e95 $29.95. You save 60%! Editors A Engineers 86 Electronic Sales Company 85 Electro Products Laboratories 87 807 SCOOP! Engineering Associates 96 Famous -make 807's at a wonderful bargain Espey Manufacturing Co. 71 400 hand, so order quick. ' Esse Radio Company 72, 73 price. Only on First come, first served. Each only Fair Radio Sales BI General Electronic Distributing Co. 76 BK -22 -K Relay Assembly General Test Equipment 74 Green Radio Distributor 92 Part of the 269 -F Direction Finder. Contains many useful Greylock Electronic Supply Co. 85 SYMPHONY GRAND Heath Company 14, 15, 16, 17 ports; 12 -volt DPST relay, 28- AM -FM RADIO -PHONOGRAPH volt stepping relay with The House of Tubes 89 Hudson Specialties 88 CONSOLE 5 -deck. 6 position switch, fuse clips, terminal boards, other Instructogra ph Company 71 A magnificent musical instrument. Mee International Resistance Company 4 parts. Brand new. atJe ,,tt Series 16 AM -FM Radio Island Radio Distributors 68 the powerful MA -2182, only ... $2 49 Chassis. Offen Flash -O -Matie Volume The JR! Trainers 85 and Band Indication; TELEVISION Lafayette -Concord 93 Audio Switch-Over; Giant 14A' Pane - FM-AM HAM ANTENNA Lake Radio Sales Company 74 sonic Speaker; Color -Ray Tuning; No- anand_ Larry Lynda Radio Supply Company 69 Drift FM. Other console and table. Leotone Radio Corporation 98 modela with Series 16, 12, or 8 chassis. Lifetime Sound Equipment Company 95 BUT DIRECT rOOM RACTOR0 AND SAVE! AN- 104 -B. 1/4 wave at 100.156 MC: formerly McMurdo Silver Company Inside Front Cover used with SCR -522, 274 -N, ARC -5. A pair Magnet Wire, Inc. 90 TODAY. Vireo IN Nam are SIND THIS COUPON make an excellent broad -band dipole for 39rs Maltz Electric Company 70 LAW. (Alone Prier) - (wpm w k Peed. FM reception. Coaxial connector in base. I! Metropolitan Electronic & Instrument Co, 92 7 MA -2153 MIDWEST RADIO TELEVISION CORP. Very sturdy. Use anywhere. Microcircuits Company 90 i Mid -America 96 Dept. 385, Broadway, Cincinnati 2, Ohio Company 909 Midway Sales Company 87. 93. 96 Plc.. rend m. your new FREE 1949 Catalog. Money- Saving KITS! Midwest Rodio Corporation 96 Mort's 90 NAME MA -2481- communication knob kit for amateurs Radio Shack and set -builders. 18 set -screw knobs for 1/4 " Moss Electronic Distributing Co. 75 ADDRESS. shafts. Many ore expensive brass -insert construc- Motor Industries Company 87 tion. Plenty of knobs to give professional Murray Hill Books, Inc. 74, 91 Lan ... ZONE STATE 1 appearance to any transmitter, receiver, etc. National Plans Company 96 A really terrific value $7.49 National Rodio Institute 3 National Schools 5 MA- 50870 -31 miniature base pilot light sockets Newark Electric Company 97 -builder's MINIATURE STORAGE in a great assortment to meet every set Niagara Radio Supply Company 80, 86 needs. Never before at this low price 89r Offenbach L Reimus Company 80 BATTERIES MA- 2480 -40 push -on knobs in a wide variety of Ohmite Manufacturing Company 12 types PLUS a generous assortment of felt ush- Opad -Green Company 77 A real power supply for that pocket transceiver ers. Meets more replacement needs. All knobs Opportunity Adlets 89 (each battery 344x1;kx7/8 in.) for 1/4" shafts; no less than 3 of any type 980 Pilot Rodio 9 Precision Company 90 Real, rechargeable Storage Batteries, built for Apparatus MA- 3050 -Steatite and glazed porcelain stand- Progressive Electronics Company 87 Radio Sonde transmitters. Drycharged -just off insulators. Total of 32 in 8 different types. add standard electrolyte (1.280 Sulphuric R d M Radio Company 90 Keep high voltage and rf away from chassis or Radio City Products Co., Inc. 80 Acid). Directions included. Plugs into stand- panel. Ideal for all amateurs 79.' ard Octal socket. Radio Corporation of America 13 Radio Dealers Supply Company 64 Each set includes one 2 -volt and three 36 -volt Radio Electric Products Inc. 6$ (total 108v.) units, the latter good for 100 MA T -17 Microphone Radio -Electronics Library Series 64 intermittent drain. Recharge at 20 MA, Famous T -l7 carbon mike with built -in hiss Radio Mail Orders 80 5 with PL -68 Radtonic Equipment Company 93 Set of 4 batteries filter. -foot rubber covered cable postpaid in U.S. plug. These are used units but in perfect Rodo Ports Sales Company 69 3-00 operating condition. Don't miss out Radio Publications 95 ENGINEERING ASSOCIATES on this great value 79es7 Far Hills Branch Box 26, Dayton 9, Ohio PARI- DYNAMIC J -61 Speaker Wall RADIO SCHOOL DIRECTORY (Pages 94 -95) TO SUCCESS BAFFLE American Radio Institute 500 FORMULAS Handsome cabinet com- Baltimore Technical Institute m i li d s s tand h a e fom ufim o r pletely enclosed and fin- Candler System Company M they paid IIg price. Here . ished with simulated brown Commercial Radio Institute have salt no less-tried and tested formulas. and proceases leather and chrome trim. Don Martin School of Radio Arts makingi hing. ridic- Internal sound -absorbing Hollywood Sound Institute. Inc. low price of 25e. Here le your opportunity to start a material corrects for high - Lincoln Engineering School business p fidelity reproduction. Takes Milwaukee School of Engineering capital with undreamed profits In prospect. Youpc n also use any 6" speaker. Wonderful RCA Institutes formulas in your Own home to cut for homes, stores, offices, Radio Television Institute household eensesxp tto the bone. Or you n put them use your etc. Regular $14.50. Shpg. Tri-State College workshop to Cut to as muchmn as t. 81/2 Lbs. Not many of YMCA Trade 6 Technical Schools ,°oó . Quit paying out many dollars In these at this price. profitsfits to manufacturers, wholesalers. MA-2287 iS4.AS ..77.7 dealers. when you can make the Rodio Supply A Engineering Company .. 82 same for cents. easy when you follow The Rose Company 93 simple Instructions. Jÿ: Order from this Ad Howard W. Sams A Co., Inc. 19 66 PAGES, 3200 WORDS IN TEXT Santo Radio, Inc. 18 Send for tha.aRl' 5 AND SCI Quantities on above- listed items are strictly limited! close 5c, You asked ford another You must act last lo make sore you get what 3011 N. Silverstine Company 62, 63 cent now r later. Sold on a money-back guarantee. want. send 25rí deposit. lay balance plus postage Spartan School of. Aeronautics 83 on delivery. ttet your name and address on Slid - Spellman Television Company 81 NATIONAL PLANS COMPANY receive monthly bargain P. O. BOX 26 R. America's select mailing list to Sprague Products Company 79 STATION N. New York 23, N. Y. bulletins that give you first crack at the latest, greatest. money-saring buys In radio parts. electronic Spayberry Academy of Radio 7 equipment, tubes, etc. Send orders and mailing list Supreme Publications 57 TALK ANYWHERE data to Desk RC -IO. Sylvania Electric Products 10 Instantly To Anyone Technical Radio Parts 97 with Inter -Talkie! Just push but. Television Assembly Company ...... 66. 67 ton and talk to Or from 7 differ- .... ent places! Not phone-loud room Transvision 65 volume -no electr v plug-ins Triplett Manufacturing Company.Inside Back Cover tubes needed! Sit or hang ft! Simple and quick to hook Wells Sales, Inc. 98 For homes, STORE WAREHOUSE 69 farm, etc. ONLY E. C. Wenger Company 2412 S. Michigan Ave. 2307 S. Archer Ave. Productions 95 Gtore., Write euaranteed! for $9.97 World in Color C.c.,,. 16, Ut Chic., 16. 111. free details today! Agents wanted. EACH Wright, Inc. 85 MIDWAY SALES CO., Dept RCI, Kearney, Nebr. Zack Radio Supply Company 69 RADIO -ELECTRONICS for Book Reviews I97 POST WAR COMMUNICATIONS RECEIVER The material is listed in MANUAL Including Aircraft and Marine Radio, a cross -index compiled and published by Howard W. Same & so the reader can find a circuit although Co., Inc., Indianapolis, Ind. 81/2 x 11 inches, pages it may be known by a variety not numbered. Price of names. $3.00. The original source of material is given Amateur and commercial radio oper- at the end of each article. ators, servicemen, and shortwave lis- Engineers and students may find ma- teners will appreciate the wealth of terial in this book that will save count- technical free data on communications re- less hours spent in searching through ceivers and allied equipment made technical literature. Instructors can use between the end of the war and mid- many of the circuits to illustrate the- summer 1948. The average amateur - oretical text -book material. always wondering about the other fel- low's receiver -will find delight in cir- RADIO RECEIVER DESIGN, PART II, by K. R. cuits and on 26 communications Sturley. Published by John Wiley and Sons, Inc. data 5% x 8% inches, 480 pages. Price receivers, the Gon -Set converter and $5.50. RME's preselector and converters. This, plus Part I of the same work, published in 1943, is, in Flyers, amateur and professional the true sense For EVERYONE interested in of the word, a textbook. The author, sailors, and aircraft- and marine -radio TELEVISION RADIO ELECTRONICS technicians will be interested in data head of the Engineering Training De- partment of the BBC, has compiled all SOUND SYSTEMS INDUSTRIAL EQUIPMENT on 22 pieces of marine and aircraft ra- EVERYTHING in standard brand equipment) dio equipment. the available information on receivers. The material, prepared in the same Each portion of a receiver has been Professionals! Radio Horns! Television Enthusiasts! given Beginners' Oldtimers' Amateurs! Hobbyists! Here's manner as the Photofact folders, con- a comprehensive treatment. The one book thot's a MUST for you) Our FREE 148 page tains diagrams, keyed photographs and chapter on a.f. amplifiers, for example, catalog jammed with over 20,000 different items. is The smallest part to the most complete industrial pertinent servicing information, on all 55 pages long and all information system from one dependable sourcei except the equipment described.- R.F.S. that directly applicable to re- 24-NR. MAR. ORDER SERVICE ONE YEAR TO PAY ceivers has been excluded. A separate HANDBOOK OF INDUSTRIAL ELECTRONIC 75 -page chapter takes care of power 3 GREAT STORES: Uptown at 115 West 45th St. CIRCUITS, compiled by John Markus and Vin and Downtown at 212 Fulton St. in NEW YORK amplifiers. 323 W. Madison St. in the heart of CHICAGO Zeluff. Published by McGraw -Hill Book Co., Inc. There New York. N. Y. 272 pages. Its/a x 9 inches. Price are eight chapters in the vol- MAIL ORDER DIVISIONS: 242 W. 55th St., N. Y. 19 $6.50. ume, six of them rounding out the AM and 323 West Madison St., Chicago 6, Illinois This is a compilation of 433 practical receiver information with material on electronic circuits that have appeared power supplies, automatic gain control, in Electronics, Electronic Industries, push -button. remote, and automatic tun- .jEWARK MAIL COUPON NOW QST, Radio, Review of Scientific In- ing, and performance measurements, . is RADIO 6 TELEVISION Newark Electric Co struments, Sylvania News, RCA Review and the last with D St A 11.242 W. 55 St two dealing FM and New York 19, N.Y. and others. The authors were careful TV receivers. Please send me FREE the Newark 1949 Catalog to select only practical circuits that il- The material is compressed to give !NAME lustrate novel approaches to particular the maximum information in a given ADDRESS CITY STATE problems. The circuits have parts val- space, though the old engineering prac- ues so the reader can use them without tice of stating a proposition in very spending time experimenting or com- vague (and uninformative) terms and puting the value of each component. then restating it mathematically ap- TECHNICAL KOs The circuits are divided into 20 clas- pears to delay the reader to some ex- sifications according to function. Among tent. However, this is a minor com- Special: 10% discount on orders of $5.00 or more. the chapter headings are: Capacitance plaint. More important is the fact that OIL- FILLED TRANSMITTING Control, Cathode -Ray, CONDENSERS MICAS Metal Locating, almost every useful formula for re- .05 51F1) 1000V 50.35 .00005 2500V 50.15 Temperature Control, Timing, Photo- ceiver design is given. .05 50ov .14 .00005 3000V .35 1 2500V .75 .00005 5000V .85 electric, Ultrasonic, and Motor-Con- In short, the book is uninteresting 1 7500V 1.65 .000067 2500V .20 x.l 7000V 4.10 .00907 2509V .20 trol Circuits. Stroboscopes, voltage reg- from a literary standpoint, but an un- .12 150011V 7.95 .00025 2500V .25 1000V .35 .00025 5000V .85 ulators, multivibrators, oscillators, lim- usually complete reference text for re- 4000V 2.15 .0005 2200V .25 iters and power supplies are also ceiver design engineers, for .25 6000V 3.75 .00072 5000V .85 which pur- ü:.25 1100V 1.05 .0008 51100V .85 described. pose it was obviously written. -R.H.D 00nV .28 .0001 2500V .25 .5 1000V .40 .0011 5000V .85 2000V .75 .002 1000V .20 400V .30 .002 3000V .65 .85 600V .35 .003 2500V .30 1.0 1090V .45 .003 3000V .65 2.0 200V .20 .004 2500V .35 2.0 000V .40 .005 1000T. V .15 i.0 1000V .60 .005 3000V .65 4.0 600V .60 .006 2000V .35 4.0 1090V 1.00 .008 1200V .15 5.0 220VAC .55 .01 120OT.V .15 0.0 1000V 1.45 0.0 On0V 0.0 1000V 1.7f'8S TUBES-CHOKE -POTS 10.0 600V 1.00 'rubes -12K8 Metal .29 30.0 nOVAC 1.40 Choke-10011A-1011, 30.9 330VAC 3.75 250 Ohm 1.59 Pots: 20K- 50K -100K .19 25.0 Electrolytic 25V .40 Dual. 'h Meg 100.0 " 25V .50 '250K -501C' .30 SHIELDED WIRE a22 50 Ft. for .65 RESISTOR KIT Assorted % &1W 100 for 1.49 BATHTUB KIT 3x.1, .5, .05, ETC. 10 for .58 CONDENSER KIT .01- .00001....100 for 2.99 MICAS .01. .002, .005, ETC. All Values .0 .01 150V PAPER (MIDGET) 60 for 1.00 1.1 600V PAPER 8 tor 1.00 52.00 min. order F.O.B., N.Y.C. Add postage 50 9/e deposit, balance C.O.D. with all orders. Manufacturers inquiries Invited. Send for Flyer. Prices are subject to change without notice. TECHNICAL RADIO PARTS CO. MOVED TO LARGER QUARTERS 557 McDonald Aye., Brooklyn 18, N. Y. Suggested by J. F. Dunnett, Vancouver, B.C., Canada DEPT. RE -8 JANUARY, 1949 98 Guaranteed by WELLS Brand new, standard make tubes by the thousands are ready for immediate delivery at the lowest prices in our history. Check this list for exceptional values in magnetrons, cathode ray tubes, voltage regulators, transmitting tubes and also neon, pilot and flashlight bulbs. Be sure to order enough for future needs directly from this ad or through your local parts jobber. Type Price Type Price Type Price Type Price 01A .50 VR78 .68 838 3.25 2051 .95 1822 5.55 VR90 .70 841 .55 7193 .35 1R4/1294 .85 VR92 .65 843 .55 8011 2.55 2J22 14.85 VR105 .70 860 2.55 8012 4.35 2J31 14.85 VR150 .70 861 34.50 8020 3.25 2J32 14.85 VT127 ENGLISH .35 864 .55 9001 .70 2J38 18.95 VT127A TRIODE 2.55 865 2.55 9002 .65 2J48 16.55 211 .65 869 24.95 9003 .55 2JI58 9.85 217C 5.95 8698 28.95 9004 .55 5J23 14.85 218 4.45 872A 2.45 9006 .55 5J29 14.95 282B 4.35 874 2.15 CF972 1.55 2C26 .55 250R 7.85 878 2.15 FG105 10.95 2C26A .70 304TH 6.55 884 1.50 KU6I0 7.45 2C34 .46 3047L .90 885 .85 RK20A 4.95 2C44 1.25 305A 12.45 930 1.10 12X825 2 Amp Tungar 2.95 2E22 1.35 305B 6.75 954 .55 RK34 .45 2X2/879 .75 316A .55 955 .55 GL471A .95 3C24/24G .49 350A 2.75 956 .55 EFSO .70 3API/906P1 2.75 350B 2.55 957 .55 HY615 1.25 3BP1 2.75 371A 2.55 1005 .45 704A 1.55 3CP1 2.75 371B 2.55 2050 .75 705A 2.15 3E29/8298 3.95 388A 6.45 1148 .40 707A 19.95 3FP7 2.95 417A 19.85 1201/7ES .95 3HP7 2.95 GL434 2.95 1616 1.25 ' 5AP1 3.75 446A 1.55 1619 .55 NEON BULBS FOR RADIO USE 5111.1 2.85 4468 1.55 1624 1.25 58P4 3.95 GL471A 2.95 1625 .45 NE-15 Price Ea. .06 5GP1 6.55 481 4.50 1626 .45 NE-48 Price Ea. .24 5HP4 5.95 WL530 24.95 1629 .45 NE-16 Price Ea. .24 12HP7 10.95 WL531 19.95 1641/RK60 .65 NE-51 Price Ea. .06 6A6 .90 532A 3.55 6B7 .99 GL559 3.75 6C21 19.95 WL681 19.95 6H6 .52 7008 9.95 6J5 .52 700C 9.95 PILOT AND FLASHLIGHT BULBS 6SL7 .65 700D 9.95 6U5/6G5 .70 702A 2.95 7A7 .70 7078 23.25 Stock Mazda Watts Bulb Base Ea. 7C4/1203 .45 708A 6.55 No. No. Pelts 710A 2.15 Price 7H7 .75 350.40 64 6-8 797 .70 714AY 9.95 E 3 CP G-6 DC Bay .07 10 .52 715B 7.95 350-50 1820 28 .1 Amp Min Bay .12 10Y .55 717A .90 350-31 57 12-16 1.5CP G.4"2 Min Bay .08 .35 721A 3.95 12A6 350-42 Spec. 12 6 Watts S-6 Cana Scr .13 12C8 .35 721B 3.95 125H7 .45 7248 4.25 350-20 1446 12 .2 Amp G-31/2 Min Scr .07 19.95 REL21 3.65 725A 350-14 49 2 .06 T-31/4 Mu, Bay .06 FGI 7 2.95 726A 19.95 350-15 356 120 3 Watts S-6 Can Bay .11 30/Y767 J Fee .95 726C 19.95 33/V733 'Walk], Talkies... .95 80IA .80 348-22 PR-10 6 .5 Amp B-31/2 Min Flang .05 34 .35 803 7.75 350-18 1477 24 .17 Amp T-3 Min Scr .16 .45 805 5.75 RK34 LB-101 323 3 T-11/2 953 .22 39/44 .34 807 1.20 (Aircraft) 41/V751 .55 810 7.95 350-19 Pro¡. Bulb 120 500 Wafts T-20 Med Pf 1.45 VT52/45SPEC .55 813 7.85 LB-103 44 (Ruby) 6.8 .25 Amp T-31/2 Min 'lay .04 814 3.75 46 .85 LB-102 1195 12-16 .50CP RP-11 DC Bay 76 .55 826 .49 .14 77 .55 828 4.55 LB-104 313 28 .17 Amp T-31/2 Min Bay .11 78 .55 8298 3.95 LB-105 1816 13 .33 Amp T-3'/2 Min Bay .12 .85 830B 3.75 83 LB-106 12A 12 .09-Amp 11 T-2 Tel Base .18 83V .95 832 2.75 100R 3.45 832A 3.50 LB-107 24-A2 W E 24 .75- Amp 105 T-2 Tel Base .18 EF50/VT250 .65 837 1.25 LB-108 S 14 ARGON 105 2' 2 Wafts Med Screw .22 Cut Out This Page Distributors: Our standard jobber arrangement For Ready Reference applies. Order directly from this ad. /WELLS Manufacturers: Write for quantity prices. SALES, INC. 320 N. kLA SALLE ST. DEPT. Y, CHICAGO 10. ILL. Printed in the U.S..-I. RADIO-ELECTRONICS for JANUARY. 1949 PRINTED IN THE U. S. A. BY THE CURED PHEW INC. ,j NOTE the Sensational All Resistors Are Improvements Precision Film Or Wire Wound Types... Sealed For Permanent Accuracy. Model 630 USA. $3750 Dealer Net Unit Construction... Re sistors, Shunts, Rectifier, Leather Carrying Case $5.75 Batteries All Are Housed In A Molded Base Built ADAPTER PROBE FOR TV Right Over The Switch .. . Inside view cover HIGH VOLTAGE TESTS EXTRA Provides Direct Connec- tions Without Cabling .. removed...inverted No Chance For Shorts. A completely new Volt- Ohm -Mil- TECH DATA Ammeter that does more .... has D.C. VOLTS: 0- 3- 12- 60.300- 1200 -6000, at 20,000 Ohms /Volt proved components .... and will A.C. VOLTS: 0-3-12-60-300-1200-6000, at 5,000 Ohms/Volts give a lifetime of satisfaction. D.C. MICROAMPERES: 0 -60, at 250 Millivolts D.C. MILLIAMPERES: 0- 1.2 -12 -120, at 250 Millivolts D.C. AMPERES: 0.12, at 250 Millivolts OHMS: 0 -1000- 10,000; 4.4 Ohms at center scale on 1000 scale; 44 Ohms center scale on 10,000 range. MEGOHMS: 0 -1 -100 DECIBELS: -30 to +4, +16, +30, +44, +56, +70 OUTPUT: Condenser in series with A.C. Volt ranges TRIPLETT ELECTRICAL INSTRUMENT CO. BLUFFTON, OHIO In Canada: Triplett Instruments of Canada, Georgetown, Ontario The case C ' the Creeping Sleeve Lead sheathing on telephone cable meets many stresses - the tug of its own weight, wind pressure, contraction and expansion from cold and heat. Then, too, there's the pressure of nitrogen gas put in Long Distance cable i to warn of sheath breaks and keep out moisture. And, sometimes, lead is subject to "creep"- a permanent stretching - even when the stress is but a fraction of the normal tensile strength. Creep is especially likely at the lead vleeves used where two lengths of cable are joined. 11íe sleeve may stretch and break open exposing telephone circuits to the elements. So Bell Laboratories scientists have developed meth- r ods to test and control creep. In a special testing room, weights are applied to scores of samples of 1 ed, under controlled conditions. Exact records of the a, ount of creep are obtained with a precision instrument. Years of careful study have produced a lead ccm- position which resists creep and yet has all the other properties required of sleeves. This means better tele- phone service for you and helps give that service at lowest possible cost. It is an example of the way Bell Telephone Laboratories scientists study and improve every part of the great telephone plant. BELL TELEPHONE LABORATORIES EXPLORING AND INVENTING, DEVISING AND PERFECTING, FOR CON- TINUED IMPROVEMENTS AND ECONOMIES IN TELEPHONE SERVICE.