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POPULAR ELECTRONICS IS publishetI monthly byy Z,ITDavia Publishing Company. William B. Zia. Chairman of the Board (1946- 1953). al 434 S. W..bes,' Ave.. Chi.ago 5. Ill. Serond.elassi posi ge rani,) at Chiragn. Illinois Atinhorited hV Post Otflre Deuu,'linenl. Ottawa Caned:,. as a ,nd-elass mailer. SUBSCRIPTION RATES: One year U.S. and possessions. and Canada $4.00; PunAmertcan Union Countries $4.50, all other foreign countries, $x.uQ.

AmericanRadioHistory.Com JULY 1960

VOLUME 13 NUMBER 1

Electronic Construction Projects One -Transistor Pocket Radio Alvin Mason 43 Earphone Booster Amplifier Louis E. Garner, Jr. 46 Electronic Burglar Alarm Ed Duda 62 Radioman's Lamp Charles Coringella, W6NJV 69 D.P.D.T. Switches in Power Circuits Kenneth Richardson 98

Audio and High Fidelity Build a Picnic Speaker Luis Vicens 54 Inside the Hi -Fi Microphone Joseph Marshall 55 How to Extend the Life of Your Records John Milder 77 Communicating Through the Earth ..J. C. Fischesser 87 Stereo Amplifier -Preamplifier 90 Electronic Features and New Developments Operation Radio Control 39 TV Explores Deep Wells Harry J. Miller 48 New Developments in Product Design 50 Ship -Shaping Marine Radios Leo G. Sands 59 Magnetic Amplifiers-How They Work, What They Do.... Ken Gilmore 71 Test Instruments-The Sweep Generator G H. Harrison 80 Transistor Topics Lou Garner 84 Carl and Jerry: Tussle with a Tachometer John T. Frye, W9EGV 94 Amateur and SWL Notes from the Editor: SWL Registration Oliver Read, WIETI 6 FCC Report: Computers for FCC Robert E. Tall 8 DX'ing Down Below Tom Kneitel, WPE2AB 51 The Strange Inhabitants of 75 -Meter Phone.. James F. Van Delta, WA2FQZ 66 On the Citizens Band Tom Kneitel, 2W1965 76 Across the Ham Bands: Putting Up Antennas....Herb S. Brier, W9EGQ 91 Short -Wave Report Hank Bennett, W2PNA 97 Departments Letters from Our Readers 12 POP'tronics Bookshelf 18 New Products 24 Tips and Techniques 34

Cover photo courtesy ITT Laboratories

2 POPULAR ELECTRONICS

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AmericanRadioHistory.Com PQPULAI Editor & Publisher

OLIVER READ, W 1 ETI

Managing Editor JULIAN M. SIENKIEWIC2, WA2CQL ELECTRONI CS Feature-Editor ' World's Largest -Selling Electronics Magazine FURMAN HEBB '

' Ayt Director. Average Net Paid Circulation 295,979 ALFONS J. REICH

Aºsociote Editors RICHARD A. FLANAGAN MARGARET MAGNA PERRY WINTER, K2VLR Editorial Assistant COMING NEXT MONTH DOLORES GIMBEL'

Contributing Editors H. BENNETT, W2PNA- l H. S..BRIER, W9EGO J. T. FRYE, W9EGV PÓPI)LÁY "9r"o L. E. GARNER, JR. T. KNEITEL, 2W1965 ' ELECTRONICS Art Associate J. A. ROTH

Art and Drafting Dept, K. W. PAUL, JR. W. K. VAHLSING, WV2GYL

Advertising Director . . rm-o-Imrt JOHN A. RONAN, Jr.

Advertising Manager WILLIAM G. McROY; 2W4144

ZIFF-DAVIS PUBLISHING COMPANY, One Park Ave., New York 16, N. Y. William B. Ziff, Chairman of the Board (1946-1953); William Ziff, President; W. Bradford Briggs, Executive Vice (ON SALE JULY 26) President; Michael Michaelson, Vice President and Circulation Director; Hersh- el B. Sarbin, Vice President; J. Leonard O'Donnell, Treasurer. BUILD THE MIN -O -SCOPE An oscilloscope that's actually dwarfed by an ordi- E D o nary VTVM (see photo above), the Min -O -Scope is the ultimate in portability-and it costs only about $30.00 ABC>= to construct ilkO INC ONE -TUBE FM TUNER For less than $10.00, you can build an ultra -simple BRANCH OFFICES: Midwestern Office, 434 5. Wabash Ave., Chicago 5, Ill., FM tuner offering amazing sensitivity and fidelity Jim Weokley, Advertising Manager; Western Office, 9025 Wilshire Blvd., TAPE TECHNIQUES Beverly Hills, Calif., Don Cena, Western If you own-or plan to buy-a tape recorder, you'll Manager. want to read this article on how to get the most from Foreign Advertising Representatives: your tapes D. A. Goodall Ltd., London; Albert Mil - hado & Co., Antwerp and Dusseldorf. TUBE TESTERS The first of two articles on how tube testers work and what to look for when buying one

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CONTRIBUTORS: Contributors are advised to retain a copy of their manuscripts.cripts. and illustrations. Contributions should be mailed to the New York Editorial Office and must be accompanied by return postage.Contributions will be handled with reasonable care. but this magazine assumes responsibility ter their safety. Any copy accepted is subject to whatever adaptations and revisions are neees- a.y to meet º the remu iremnents of this publication. Payment covers all author's. contributor's and contestant's rights. e titles. and interest in .,$ to the material accepted and will be made at our currentrates upon acceptance. All photos and drawings will be considered us ea,, of mate, ial purchaseo.

4 POPULAR ELECTRONICS

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July, 1960 5

AmericanRadioHistory.Com Notes from the Editor

SWL REGISTRATION. Just the other day we received a tabulated report on the Short -Wave Monitor Registration Program that was sponsored by POPULAR ELECTRONICS last year. Here are some of the statis- tics from the report which I think will interest you. The tabu- lation, incidentally, was based on 12,948 registration forms received up to January 1, 1960. First of all, let me fill you in on the purpose of the registration program itself. There had long been a need for the "SWL" to have some individuality. Unlike hams, who are licensed by the government and assigned their own call letters, short-wave listeners had no one to turn to and were "lost in the shuffle." We decided to do something about this situation --it was high time each DX'er had his own "call sign" to use on his QSL cards rather than the anonymous "W5-SWL" type of identification. We then devised the now -famous "WPE" call signs, cleared them with the FCC, and began issuing them to DX'ers. The most striking bit of information extracted from the tabulated report was that 41.2% of the registering short-wave monitors own more than one receiver. These receivers are not home-brew one - tube regen sets but top -notch -quality all -band receivers that would make the average ham turn green with envy. Manufacturers whose receivers were listed the most times were --in order-- Hallicrafters, National, Allied Radio (Knight and Knight -Kit), and Heath. All together, these manufacturers accounted for 65% of the receivers owned by the registrants. The most frequently listed receiver was --you guessed it --the Hallicrafters S-38. Various models of the S-38 are being used by almost 10% of the registrants --quite an endorsement of this old favorite. The second most -used receiver was the Heath AR -3, a unit which has started many an SWL on the road to this rewarding hobby. The most popular bands monitored are 20, 25, 31, and 40 meters --more than 20% of the registrants reported that they listen to these bands regularly. Over 55% of the monitors use a long-wire antenna; however, many prefer a high -gain beam antenna of some .kind --with a few using antenna rotators. One last statistic points out.the degree of interest that most of. the registrants have in short-wave listening: almost one out of ten reported that he had already obtained over 100 QSL cards. The overwhelming number of applicants for the certificates made the registration project worthwhile and helped us gain a great deal of valuable information about our SWL readers in addition to reaffirming our belief that DX'ing is a serious and vital electronics hobby. We hope to translate this information into better, more interesting coverage of the SWL field.

6 POPULAR ELECTRONICS

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AmericanRadioHistory.Com TIME TO CLEAN UP YOUR SYSTEM . n a

ore co® T-7 LOUDSPEAKERS with voice coil magnets of ?___ Report Ticonal-7 steel (30% more efficient' than Alnico V) 1 t , By ROBERT E. TALL O... 30% more efficient i- Washington Correspondent response to the full signal range of your amplifier ... WHETHER ITS RATED OUTPUT is Computers for FCC 10 WATTS or a HUNDRED... at any listening level from a HE electronic data processing bug has whisper to a shout! I bitten the FCC. At the moment, chances look good that the Commission will be GUILD -CRAFTED BY PHILIPS OF blipping out your Citizens Band licenses by THE NETHERLANDS TO GIVE YOU machine in a few more years. Studies are already being made by the National Bureau THE of Standards to see which parts of the FCC's activities can be fitted into computer operation, but it will probably take CLEANEST until early 1963 for the Commission to make the necessary decisions and get the program into full swing. SOUND Word on the computer plans was passed to the House Interstate & Foreign Com- AROUND merce Communications Subcommittee when the Commission went up for its annual quizzing in connection with appropriations for the year starting July 1. Several of the Congressmen briefed on the plans expressed quick support. FCC Executive Officer Robert W. Cox told the subcommittee that both the Bureau of Standards and the Commission feel it is "premature" to say how much money can be saved or how much faster work can be done by a computerized operation. How- ever, both agencies are "very optimistic" about the possibilities. The big question concerning the Citi- zens Band and other two-way radio fields administered by the FCC is not whether the Ask for a machines can handle license processing, but demonstration wherever whether they can do the work more eco- good sound is nomically. A decision as to whether or not sold or write to: to swing into a full data processing pro- NORTH gram will probably be made by the FCC AMERICAN this fall. If the agency goes the computer PHILIPS route, another complete overhauling of ap- CO., INC. plication and license forms is indicated. Chairman Albert Thomas (D., Tex.) of High Fidelity Products Division, 230 Duffy Avenue, the House Subcommittee said the work of Hicksville, L.I., N.Y. the FCC's Safety & Special Radio Services

8 Always say you saw it in-POPULAR ELECTRONICS

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AmericanRadioHistory.Com Bureau, which includes the Citizens Band Model activities, should fit into computer. opera- C-25 tion "just like it is made to order." If the New "In program is undertaken, it very definitely Circuit" should mean much quicker application Capacitor Model T-61 New "Speed Tester Kit processing. Check" Tube Tester Kit - Kit Net Price $49.95 Kit Net Price $19.95 Citizens Band applications were being Factory -wired Net Price $69.95 Factory -wired Net Price $29.95 received by the FCC at a rate of more than 10,000 a month, and the FCC told the Model T-5 , Model SC -1 House members that since "an estimated 50 New t New firms are making or planning to make the Rapid 1 ' Condenser Filament relatively inexpensive Citizens Band equip- Substitution Tester ment, a steady in Box Kit rise receipts can be ex- 3 Kit pected as sales promotion plans get under Kit Net Price $4.50 Kit Net Price $8.95 way and competition results in lowered Factory -wired Net Price $6.50 Factory -wired Net Price. $11.95 prices." The Congressmen sitting in on the sessions did not raise many questions when ...and now PRECISION they were told that the Commission ex- pects the Citizens Radio Service to grow 'addsl0 more value -packed to an estimated 200,000 licensees this year, and that the blossoming service has re- °kits to the p A quired enforcement action "leading to the issuance of at least 100 citations per month" for violations. The FCC asked for money for added en- Model CD -3 Model SR -2 forcement personnel to handle problems in- New New volving class D licensees, which will "un- Decade Resistance a' Condenser Substitution doubtedly increase as the band becomes Kit Box Kit saturated." Individual CB enforcement 6 cases continue to involve primarily off - Kit Net; Price $19.95 Kit Net Price $8.95 frequency operation Factory -wired Net Price $24.95 Factory -wired Net Price.$11.95 and failure to answer FCC violation notices. Amateur radio, meanwhile, got a large Model Model RD -5 ~Mt national publicity boost when a live broad- 11 _ ñ » ST -45 New Decade cast account of the annual meeting of Pres- Resistor/ New AM -FM ident Eisenhower's Committee on Employ- Divider Kit Stereo Tuner Kit 8 ment of the Physically Handicapped was 7 Kit Net Price $84.95 transmitted to physically handicapped and Kit Net Price $23.95 Semi -kit Net Price $99.95 Factory -wired Net Price $29.95 Factory -wired Net Price $134.95 other radio enthusiasts throughout the world. Model L2 -U Accounts of the May 5-6 meeting in New Washington were Wide-Jtange put on the amateur airways by Miss Margaret Cauffield Model ST -35 Two -Way Speaker (W3UTR) -Kit New FM Tuner Kit. System Semi and Gordon Walker. Miss Cauffield is a 9 Semi -kit, unfinished wheelchair -bound "ham" employed by the Kit Net Price $59.95 1U Net Price $59.95 Office of Vocational of Semi -kit Net Price $69.95 Semi -kit, walnut finish Rehabilitation the Factory -wired Net Price $89.95 Net Price $69.95 Department of Health, Education & Wel- SEE'THESE KITS 0 N DISPLAY AT'ANY fare; Mr. Walker is also confined to a LEADING ELECTRONIC PARTS DISTRIBUTOR wheelchair and is an electronics engineer with the Navy's Bureau of Ships. The station they used was loaned for. the m0dm venture by a Washington electronics and

. PACO Test Equipment and Hi Fi Kits are produced under the auspices of PRECISION Apparatus Company, Inc., world- radio parts firm. It was operated with a famous manufacturer of industrial electronic test instruments power of about 145 55' x 35' and stereo high fidelity components for over a quarter of a watts, with a century. Write to Dept. P for the new complete 1960 PACO Cata- antenna supplied by the Naval Research log, just off the press. You'll keep it for permanent reference. PACO ELECTRONICS COMPANY, INC. Laboratory on the roof of the Departmental 70-31 84th STREET, GLENDALE 27, L. I., N. Y. Auditorium in Washington where the meet- Kit Division of PRECISION Apparatus Co., Inc. ing was held.

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F.C.C. LICENSE-THE KEY TO BETTER JOBS Learn by Correspondence or in Resident Classes An F.C.C. commercial (not amateur) license is your ticket to higher pay and more interesting employment. This license Grantham training is offered by correspondence or in is Federal Government evidence of your qualifications in resident classes. Either way, we train you quickly and electronics. Employers are eager to hire licensed technicians. thoroughly ---teach you a great deal of electronics and WHICH LICENSE FOR WHICH JOB? prepare you to pass the F.C.C. examination for a first rr The THIRD CLASS radiotelephone license is of value class license. Get details now. Mail coupon below. primarily in that it qualifies you to take the second class examination. The scope of authority covered by a third class license is extremely limited. The SECOND CLASS radiotelephone license qualifies This booklet you to install, maintain and operate most all radiotelephone liridswd equipment except commercial broadcast station equipment. The FIRSI CLASS radio telephone license qualifies you FREE! CAREERS' to install, maintain and operate every type of radiotelephone " equipment (except amateur) including all radio and tele- 1tFaJNICS, vision stations in the United States, its territories and pos- tl. sessions. This is the highest class of radiotelephone license This free booklet gives available. details of our training -d and explains what an GRANTHAM TRAINING PREPARES YOU F.C.C. license can do for The Grantham course covers the required subject your future. Send for o..., v f matter completely. Even though it is planned prima- your copy today. rily to lead directly to a first class FCC license, it does _ this by TEACHING you electronics. Some of the subjects covered in detail are: Basic Electricity for HERE'S PROOF... Beginners, Basic Mathematics, Ohm's and Kirchhof's Laws, Alternating Current, Frequency and Wave- that Grantham students prepare for F.C.C. examinations in a length, Inductance, Capacitance, Impedance, Reso- minimum of time. Here is a list of a few of our recent graduates, nance, Vacuum Tubes, Transistors, Basic Principles the class of license they got, and how long it took them: of Amplification, Classes of Amplifiers, Oscillators, license Weeks Power Supplies, AM Transmitters and Receivers, FM Mario Bldese, 342 Alexander Avenue. Greensburg, Pa. _ _ -_ _ - _1st 12 Transmitters and Receivers, Antennas and Trans- Richard M. withal. 2t04 Santa Paula. Las Vegas, Nev. - - - - _ - _1st 12 mission Lines, Measuring Instruments, FCC Rules Larry R. Perdne, 7 Normandy Place. Champaign. Ill._ _ - - _ - - - _1st 15 and Regulations, and extensive theory and mathe- Emerson F. Lawson, 111 Excelsior Ave., Union, S.C. ______.1st 12 matical calculations associated with all the above Marion Woolsey. 3246 Warwick, Kansas City. Mo. _ - _ - _ -1st 12 Harold W. Johnson, 5a10 Hermosa Are.. los Argeles. Calif._ _ _ 1st 15 subjects explained simply and in detail. - - - Arthur W. Hardy, 66 Dresser Ave,. Great Barrington, Mass. - 12 - _ _ _ --1st Ralph Frederick Belsner. 2126 Grand, Joplin. Mo. _ - _ _ _ - - -1st t2 OUR GUARANTEE N. B. Mills, 11, 110 So Race St., Statesville. N C. - _ - _ _ - - 1st it If you should fail the F. C. C. exam after finishing our Dean A. Darling, 403 S. Chase Are., Columbus 4. Ohio. ______1st t2 course, we guarantee to give additional training at NO Paul D. Bernard. 408 Feint Are., H.E.. Watertown. S.D. _ _ _ _ -1st-1st t6 ADDITIONAL COST. Read details in our free booklet. Gerald L. Chopp, 518 Aubudan Road, Kohler. Wisc. - ______1St 12

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u. .Grántham. School.;1 of -ÉlectOorilics r RESIDENT CLASSES (Mail in envelope or paste on postal card) HELD IN FOUR CITIES TO: GRANTHAM SCHOOL OF ELECTRONICS you If are interest- 1505 N. WESTERN AVE., HOLLYWOOD 27, CALIF. ed in attending day Gentlemen: or evening classes Please send me your free booklet telling how I can get my commercial F.C.C. license quickly. I understand there is no obligation mail the coupon for and no salesman will call. free information to our home of- Name Age Address fice in Holly- wood, Calif. City Slate

I I am interested in: O Home Study, Seattle classes I

Hollywood classes, Kansas City classes, Washington classes MAIL COUPON NOW-NO SALESMAN WILL eCALL*-L 03 -Ka July, 1960 II

AmericanRadioHistory.Com If P.E. fails to provide articles of general interest, it is up to us "members" to make our "officers" aware of it so they can correct the situation. We "members" hold the controlling interest since the "dues" are our "officers'" bread and butter. DON F. LAMPREY Schenectady, N. Y.

Right you are, Don. We can only add a hearty "Amen." Extra Copies Out There? For the past two years I have been trying to Club Members Wanted locate copies of the 1955 May and June issues of It seems to me that you frequently publish let- POPULAR ELECTRONICS. I am willing to pay any reasonable price including ters from readers who want to form clubs to pro- for them, postage. mote their favorite areas of electronics. Although JOSEPH A. PALMER 9 Brouillette St. I am sure these readers have good intentions, I doubt that many of them know exactly what Lowell, Mass. functions they wish their clubs to perform, and that even fewer have a satisfactory means of Batteries for Solar Cells communicating with other 'members (unless the I thought you might be interested to know that club is local). I just finished building Donald L. Stoner's 40 - Personally, I like to think of POPULAR ELEC- meter solar -powered transmitter described in the TRONICS itself as a club, with each issue serving August 1959 issue. Instead of solar batteries, how-. as the club bulletin. If you consider the monthly ever, I used two penlight cells for power. With cost of the magazine as dues, this is a pretty in- all -new parts, the total cost came to $6.91. expensive club to join. No matter what the topic BILL JACOBS -.if it is of general interest-there seem to be Boardman, Ohio regular articles in P.E. pertaining to it. If there aren't many articles on a particular topic, chances Capacitors are that few people are interested in it, and thus Congratulations on your fine article on capaci- one would have a difficult time forming a club to tors which appeared in the April issue. This is the promote it. first simple, yet concise, article I have found on

Each and for ery t mutual undueconductance ube is tested We to our ' maguarantee and life own laboratory purchased replacement fo;sl. y

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AmericanRadioHistory.Com MOBILE -FIXED CONVERTER Letters (Continued from page 12) POLICE FIRE CITIZENS' BAND the subject anywhere. It was not only a refresher For Use with for old-timers, but an education in itself for any a ui 12 V. Transistor Type Car Radios newcomer to the electronics field. In almost five 26-50 MC .. 5331H-Complete with crystal and . tubes. Requires no high voltage supply. Operates on 12 V. DC. Self installed in seconds. $24.95 Other models for 108-162 MC avaialble. #31SA is a practical converter for emergency use. Easily installed. Tuning range approximately 12 MC in the 26-50 MC band-30 MC in the 108-174 MC band. Designed for mobile or home use. sY, $ 13.95 Available crystal controlled up to 54 MC. $ 1 9.95 Also available crystal controlled up to 165 MC. $22.95 years of hamming, I had never been able to find #316I, V 1RIAISLE CONVERTER. Front a good, clear article on capacitors before. panel tuning permits rapid change be- BRUCE \V. \VALLACE, K8OIG/AFA8OIG. tween separated signals over 10 MC range in 26-54 or 108-174 MC bands. Rochester, Mich. $ 19.95 #3-I1A ('ITIZENS BAND TUNEABLE Canadian Novices CON% ERTER. This universal converter covers the entire Citizens Band and is I would like to start a move to have Novice designed for use with home. ear or com- licenses issued in Canada. Any Canadian S\VL's munications sets-AC-DC or standard models. Also available: 200-400 KC Air- who are interested in becoming Novices are invited craft, 2-:t M(' Marine. 4.5 Mt' -('AP, or to send me their signatures so I can forward them, Amateur 2-3(1 M('. $24.95 along with our arguments, to the Department of Full line of converters and receivers for every application. Transport. ORDER TODAY or WRITE for LITERATURE DAVID A. GRANGER 73 Sunninghill Ave. "KUNá :ELECTRONICS Hamilton, Ontario, Canada - 20;GLENWOOD' CINCINNATI l7; OHIO Information Please I recently bought a surplus receiver called a "R2/ARR 3." It works well but I can only pick V ++ up channel 4. Can you tell me how to convert it Z1o,," óo -/ / 44451'5R 0r =r-111' s' F t11 bob.. LEADS AGAIN WITH CITIZENS BAND "RADIO -PHONE" Ott/ TR-800 TRANSCEIVER ONLY to the FM broadcast band, or where I could get the necessary information? JOHN BECKETT .95 338 Inverness Ave. East LIST Hamilton, Ont., Canada

a á -.odd"' Furnished with Ceramic Can anyone out there give Reader Beckett Microphone and one helping hand? Transmitting Crystal For Communication on the move! BC DX'ing I was glad to read Mr. Leitch's letter in the Superhet Trans -Receiver On -Off & R. F. Indicators 5 Channel Transmit Noise-Limiter Control .April issue concerning BC'ing, for I would like to 22 Channel Vernier -Tuned Mobile Mounting Brackets see broadcast -band listening come into its own. Receiving Included Although I am also a short-wave enthusiast (I've I. 5 Watts Input -Plate Modulated Power Supply Available For in R. F. Amplifier 6 and 12 Volt Operation logged 35 countries, 12 verified to date), listening on the broadcast band with my Hallicrafters Write for Brochure and Name of Your Nearest Dealer S -38E provides a bigger thrill-I've been doing it UNITED SCIENTIFIC LABORATORIES, INC. for about a year now, and short-wave listening 35-09 37th AVE., LONG ISLAND CITY I, N. Y. was never so much fun. Also Mfr's of DeWald RI -FI Stereo Components and FM Radio s On the BC -band I have thus far logged 244 stations, covering 27 U. S. states, three Canadian 14 Always say you saw it in-POPULAR ELECTRONICS

AmericanRadioHistory.Com frequencies while leaving lower frequencies unaffected. The loading plugs force the sound to travel a circuitous path, producing in - phase sound regardless of the frequency of the signal. Coupled to the Avedon Sonophase Throat Design is the Hoodwin Diffraction Horn, designed to in- sure sound dispersion throughout the listening area. This is especially important in stereo application to prevent the "beamed" or directional nature of most high frequencies.

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o a:....a.-=- sible distortion, or mechanical im- perfections prior to shipment. Such care in manufacturing and testing assures maximum reliability, all-important stability, and remarkable uniformity within dynamic types. FINE NEW HAM Loading Plug DYNAMIC MICROPHONES RECEIVER PASSES THE

' A, YOU CAN DEPEND ON ... TOUGHEST TEST OF ALL ALWAYS An interesting story lies behind the recent performance testing of "How stable?" is the question the first RME 6900 Communica- asked most often about a micro- tions Receiver. After final inspec- phone. Once the type of installa- HORN -LOADED TWEETERS tion of the first unit, one of the tion is determined, it is essential RME executives (W9IOP), de- that frequency response and direc- PROVIDE CLARITY WITHOUT cided to use this new receiver in tional sensitivity characteristics the 1960 Radio Amateur Sweep- remain unaffected. This is stability DISTORTION stakes. This contest, sponsored -and should remain constant. It Electro -Voice Tweeters are noted each year by the Amateur Radio a the wide acceptance is clue to for clarity and low distortion. But Relay League, determines which and universal use of the Electro - amateur operator can establish Voice family of dynamic micro- obtaining that clarity was a critical problem until E -V's develop- the most radio contacts in a given phones-a family comprising 35 40 hour period. different models, each designed ment of the Avedon Sonophase The receiver was delivered for a specific application. Highly Throat Design. to developed precision tooling, ex- VHF tweeters handle the widest W9IOP only three hours before tensive research, and functional range of response -from 3500 to the contest began. In spite of his design have created instruments 20,000 cps. E -V tweeters function lack of familiarity with the re- of outstanding ruggedness and as a true piston in the ower range, ceiver, W9IOP not only won logged record - durability. All internal parts nest but at the critical point (about the contest, but a breaking 1,369 contacts to estab- or interlock to prevent any move - 12 kc) sound must be taken from á ment of the reproducing mechan- the center of the diaphragm and lish a new national Sweep- ism even when the case is subjected from the periphery at the same stakes record. to severe shock. In addition, the time. Without some way to pre- The RME 6900 Communications exclusive Acoustalloy diaphragm vent it, sound cancellation occurs Receiver is the product of over 30 assures smooth response and re- because of diaphragm deformation years of high -frequency receiver liability far surpassing ordinary at and above this critical fre- design. Engineered by radio ama- demands. This vital moving ele- quency. This deformation causes teurs - for radio amateurs - it ment has no equal in withstanding phase shift to occur between the incorporates every conceivable high humidity, temperature ex- center and periphery of the dia- operating feature to facilitate tremes, corrosion and mechanical phragm. Increasingly higher fre- working today's busy ham bands. the phase shift to impact. Laboratory tests reveal quencies cause For more information write be more pronounced because of only two ways to damage Acoust- Dept. 70P alloy: heat the microphone so hot an ever increasing deformation of it can't be handled, or actually the diaphragm. puncture or tear the diaphragm. The Avedon Sonophase Throat Each microphone type is field- Design accomplishes the vital res- tested prior to acceptance for man- toration of phase relationship and EleC.99deG® ufacture and, when in production, level by incorporating a compres- ELECTRO -VOICE, INC. every model is evaluated for exact sion driver with unique loading Buchanan, Michigan frequency response, level and pos - plugs which properly phase upper July, 1960 I5

AmericanRadioHistory.Com RESIDENT SCHOOL COURSES IN Letters LOS ANGELES AND NEW YORK CITY (Continued from page 14) provinces, and nine Mexican states. In addition, START YOUR CAREER I have picked up two Cuban stations but have not yet been able to enter them in my log for IN óELECTRONICS NOW lack of adequate identification. I am hoping that the hobby of logging in the AT RCA INSTITUTES.... broadcast band will soon begin to interest more and more fans of the airwaves. I sincerely believe that BC'ing deserves a great deal of attention, for Choose from this -list it is most fascinating. Length o} DONALD BURLESON Course Qualifications Course Wichita Falls, Texas A Advanced Electronic High School grad, with Day 21/4 yrs. Readers interested in joining a Technology (T-3) Algebra, Physics Eve. 53/4 yrs. BC DX'ing club or Science should contact the National Radio Club, Box ó3, Kensington Station, Buffalo 15, N. Y., or the B TV and General 2 yrs. High School, Day 11/2 yrs. DX'ers Radio % Electronics (V-7) with Algebra, Physics Eve. 41 yrs. Club Jim Ernst, Mahone Bay, or Science Nova Scotia.

C Radio & TV 2 yrs. High School Day 9 mos. Car Radio Servicing (V-3) Eve. 21/4 yrs. Conversion Thank you for the fine article on "How to Convert a Car Radio for Home Use." by E. G. D Transistors' V-3 or equivalent Eve. 3 mos. Louis in the February issue. I bought a used car radio like the $2.50. E Electronic 2 yrs. High School, Eve. 3 yrs. just author's for I used a Drafting (V-9)' with Algebra, Physics Stancor PM8419 transformer for the conversion or Science and the radio works swell-no hum or noise of any kind. I haven't it F Color TV V-3 or equivalent Day 3 mos. put in a cabinet yet, but Eve. 3 mos. it really pulls in the stations. ELDRIDGE BRANDON G 'Audio -HI Fidelity' V-3 or equivalent Eve. 3 mos. Hazel, Ky. H Video Tape' V-3 or equivalent Eve. 3 mos. Manual Wanted

I Technical V-3 or equivalent Eve. 3-18 mos. I urgently need a copy of War Department Man- Writing (V10) ual TM11-300AF for Frequency Meter BC -221 (SCR -211 -AF), frequency coverage 125 kc. to 20,- J Radio Telegraph 2 yrs. High School, Day 9 mos. Operating (V.5)' with Algebra, Physics Eve. 21/4 yrs. 000 kc. I will gladly forward an International or Science Money Order for the cost involved. RoN YOUNG K Radio Code (V-4)' 8th Grade Eve, as desired D. 3 Bell Hill

L Preparatory Math & 1 yr. High School Day 3 mos. Danbury, Chelmsford, Physics (P-0) Essex, England

M Preparatory 1 yr. High School Eve. 3 mos. Mathematics (P -OA) Young Mexican Fan I like see 'Courses to be added to Los Angeles Curriculum thought you might to a picture of my son, Enrique, shortly after he went to sleep read- .ItCA Institutes is one of the largest technical institutes in the United States devoted exclusively to electronics. Coeducational Day and Evening classes. Free placement service. Applications now being accepted. .fi r,__ t, mi l ' Jn:O nF The Most Trusted Name diXis ~ in Electronics RADIO CORI'OR:\TION OF AMERICA nett tnsrmnts1 ?- \ Send to the school nearest youl- , -- ó RCA Inc., Dept. PER -70 ~P Institutes, P" 350 West Fourth Street Pacific Electric Building . "~th New York 14, N. Y. 610 S. Main St., L.A. 14, Calif.

Please send me your FREE catalog. I am interested in the courses circled below.

A BCDEFGHIJKLM ing a copy of POPULAR ELECTRONICS. Enrique is Name only four years old, but he enjoys your magazine (please print) Address very much. MANUEL MENDEZ City Zone State Jalapa, Mexico For Home Study Courses See Ad On Opposite Page Then how corve it put hire to sleep? -[1- 16 Always say you saw it in-POPULAR ELECTRONICS

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17 July. 1960

AmericanRadioHistory.Com P01:21-tr4arlé+cs 2201 E. 46th St., Indianapolis, Ind. 168 pages. Soft cover. $2.50. INU Bookshelf One of the best substitutes for actual bench experience is Bob Middleton's series of "101 Ways" hooks. 1.1111 This latest volume, which discusses the use of test equip- "APPLICATIONS OF ELECTRONICS" by ment generally asso- Bernard Grob and Milton S. Kiver. Pub- ciated with amateur lished by McGraw-Hill Book Company, 330 radio operation, is a touse W. 42nd St., New York 36, N. Y. 628 pages. worthy addition to Hard cover. $7.00. the series. The spe- I ' Intended as the second volume of a two - cific equipment cover volume set, this book takes up where Mr. ered includes the Grob's previous book, "Basic Electronics," grid -dip meter, the left off. It can be used alone, however, by antenna impedance anyone who has a basic knowledge of elec- meter, the VOM and tronics. Topics include vacuum -tube ampli- VTVM, the oscillo- fiers, transistor amplifiers, receivers, test scope, reflected -power and instruments, SWR meters, industrial electronics, military plus bridges and some other miscellaneous electronics, and electronic navigational aids. equipment used to perform various types Recommended as a text or reference. of measurements. This book is well worth careful study since the diagrams and explanations of the "101 WAYS TO USE YOUR HAM TEST testing procedures illustrate many aspects EQUIPMENT' ' by Robert G. Middleton. of electronic theory. Consequently, is Published by Howard it W. Sams & Co., Inc., recommended not just for hams but for

ALL TUBES INDIVIDUALLY SMASHES .-.PRICES BOXED UNCONDITIONALLY FOR ONE YEAR GUARANTEED omplte be List ON Send Free 8 ' 0 derr Blank. Yore Inquiryu Will Mailing List EL!RO Put You on Our SAVE ONTUBES ALforL New Price Schedule of TUBES EICOz5ERBE TELEVISION PICTURE TUBES HERE'S A PARTIAL LIST .1115 OF MOST OFTEN FREE 1I+..V ..1>43 1004 1915 7104 .. 1.,5 45 USED E, < A TUBES 14AY .1643 IAY .. e3 1e25 1º23 51274.. 17 23 . 42 .1y3. .4º with Purchase of 1e04 399 .137s lolls];. 6227 .... At e f1Awºe e.73 2004 . .eo o 16074 145 v4 6 rJ Y! $100. +Recur. Tubes 1)75 21E4 17.23 . ss124117 ; 1193 ]111V4. . IeJ3 2104 'tee 3 43 in 60 Days. Buy it for ' I9.15 NA4 2725 .. .70 `023° 1024 . 11213 21A 1525 21124 IRS N.. 51.53 24a.4 ...2873 .51 6018 40 O 534.95 . ppd. :¡"vPV ... 13.ás 114 4a 60040r 0 PICTURE GUARANTEED FOR ONE (1) YEAR 0 64 1201: 1. d ,"b Sa 6AOS4a Boss' 12056 W wb p.,l. o d.c o e 4v 6BGBG with 510. , xxe . 1' dlAbne 3100 ..' Ada a. -1 i 570D e 1. 19'^ M", I 'FREE ]e. .42 6.6113CT 742 60 as 12111 .]º .e,a .1.1209ºilWld tr. ab. _o.e. 10} 49 57.50 pkg. inc. 3- 6SN7 ad w,e h. úse. ..,. . 4a 16 .N ..ac,. . ,rt eo 116.042, ,... 1022. 1}0.+} plus CY. .. JS a7 406.01. 25 td.tubes with " " Awe 1}006 FREE e ... __ 1 4:x6', 4 ..ú $25. +order! :0 44.7 64 500 TVs ]FR7 ff TRADE IN ry r]E24 CHANNEL MASTER ANTENNA q° 49 asx7 ¡5 FOR QUICK SALE séci 11.4 KIT. COMPLETE WITH 8 "USED TVs ..:ú .yo45001 AO ELE- 1145 44 MENT ANTENNA. We have purchased from a huge appliance CHIMNEY ae 31 ^a es.7 34 store a quantity ee7s 007... AS STRAPS, 50 FT. of used TVs. The sets lore . 300 OHM LEAD rem ° . _SI tecb' I. .. 21 125x7 IN, ALUMINUM MAST, STAND excellentex condition and most are Standard 3 95 een. .. sus ...4 6 - . 10001'.... 3 , Brands. Sixes run from º61e:.....43 s, tae, - °4 - OFFS AND INSULATORS. 57.99 12" to 24" - Excel. as is . ºSu au sl 'ere ew. lent for second ILt or for 404 .64 e4 I]v r LOTS OF THREE ewbbi ü - - - - $7.49 SwETS (cominemol sa RAILWAY EXPRESS FOB our USA 6 4eo>.... .7s 04 27 FOB HARRISON, N.J.IM. eax> .. .n DLVY. arehousePEO Conada ex. "'' ,>Ax.er so m e18: only) 204 ...,' 2e Z.:. 5 ' 7" 2AW :11.---..: .. 4m6 . 17p -.p HEAVY DUTY SOLDER GUN. ss 0 < 4 - - PREPAID $4.95 - 3 for 514.29 SELF-SERVICE 403 74 8047 10641:44 ,, 3'0601 .1v ' CHANNEL MASTER SWITCH seos a G`G sa .ºu .5i 6602A2 .43 ]"0164 "Ara º0. 1 TYPE RABBIT La .. 21 EARS__. $2.99 ; TUBE CHECKERS ey3G .23 :.5 '0 ` ... 34 !d 0 LOTS OF 6 52.49-- -PPD. e's These reconditioned console model 22 socket ,4d Itcr7 - snv _ .. ..il Sfw.cr rube checkers have provena 6V43pr. VIBRATORS1.59 pro their 27:4.0.. _ busy shops. a . pr. repair Let your tube c is am :_ .95 6 test their own 4 G 12V 4 pr. _ _ _ _ $1.99 tubes. Your investment will be 3 ... ]Ale worth41 ascser returned in one DURABLE ALUMINUM week with little effort on Your FOB 3164.° 2Aue RARUIT EARS _ _ 51.69 Pa H- COMPLETE WITH KEY FOR BOTTOM WAREHOUSEOUR2A) '° .4s-"- .0 ,..s3 swea Ilnu> _ ' DOOR AND NEON LIGHTED toes -_ PARALLEL TUBE PPD. ,,.. ca ye...±.ua sv4c BRIGHTENERS ,I :I:nat. anr,Jar r. HEAD..4,.. .o . v . _ - ..._ 4v 4003 _5.99 l.v Tre.,.. n.. .,,,.,n,,,,. r,..r .v _.. - - e .-,,,....,, sv> e0 sat,s een.. T...tv..rt.. 3:.. dnon r.n..r..l o, 124x.'.. pn,.. 3w, r ..i.1 ., i.mIn,.r. ,.:.:::e.., CwWn sosa'! so ...I.,WN. .Y ue n ..,,..er 6 NGr_ 124I} ,n,,.. m., I . Aa w ºqe I.ni- 6Cxa `' 1'22'01 3 Send .5} 1 far FREE c m Jlete list ofm often ELECTRIC CÓ = .., ot4-9 used tube B2es. T E,.LrT RÓI. 428.HARRISONrAVE.,428 HARRISON, N. J. I8 Always say you saw it in -POPULAR ELECTRONICS

AmericanRadioHistory.Com YOU of i, - pvalue be the judge A tkUCT OE 'Oat SW ó, FREE examination privilege More and more people are finding quality of the components, the cir- out how easy it is to build exciting cuitry, the easy -assembly manual. r t Knight-Kits, how satisfying they are We're so confident you'll want the .:..... ,. to own, and how much they save. kit, we can make this offer: If you're ' If you haven't yet enjoyed the ex- not COMPLETELY SATISFIED, just re- a041..- perience and fun of building and own- turn the kit for full refund. ing a Knight-Kit, we invite you to take advantage of our free examina- Order a Knight -Kit now. Know the tion offer. Order any Knight -Kit. thrill of the most satisfying build - Examine it on arrival. Inspect the your-own experience in electronics. easiest to build... satisfying to own ...money -saving ONLY $2 DOWN on orders up to $50; $5 down on orders

ñ.e ' Citizens up to $200... : Y-713. Best-selling ás0..°.. Band Transceive, Tunable Y-737 "Ranger" re- Clo h -Ratio 22 -channel sdper-regen with "sleep" switch...124.95 - ceiver 39.95 see scores of - -AM Stereo Hi Y.731 Deluxe FM only $2 down add -in) $87.50 only $2 down other knight -kits ¿Tuner (Multiplex only $5 down HI -Fl KITS ' Stereo Preamplifier 50 -VI Stereo Amplifier .: Monaural Amplifiers Hi -Fl Tuners © V-771 5 -Transistor Superlwt V Portable Radio (less battery) Speaker Systems e and others Y -2S8 4 -Band "Span Master" $25.95 only $2 40 -Watt Stereo Reces er (with cazinet).$25.95 down Y774 Deluxe Cha79 HOBBYIST KITS (with Center only $2 down ° Amplifier 50 "Space -Spanner" Radio tc" only $5 down "Ranger" Radios Transistor Radios 2 -Way Intercom Electronic Lab Kits and many others e___á -INSTRUMENT KITS V121. General-purpos3 Lab AC VTVM - VTVM (11 meg.Input rest 20 -Watt VOM's Super -Value R100 Amateur Communica- $25.74 Y-773 ....$44.50 only 5" Hi -Fl Amplifier tions Receiver ;Hi -gain, with $2 down Scopes Stereo Tube Checkers only $2 down built-in Q-Multlplier)..$104.50 only $5 down 41% Sig ial Tracer Audio Generator =a Sweep Generator plus many others AMATEUR KITS Y-143 Model "600" Tube 50-'Natt Transmitter Che;ker (checks over Self -Powered VFO HI-FI Tuner 700 types) $32.95 100 kc Crystal Calitrator x )a k) Multiplex1p Y-7081000 Ohm/Volt Pocket only $2 down Code Practice Oscillator only $2 down Volt-Ohm-Ivriiliammeter Grid Dip Oscillator $9.95 a -1, ALLIED RADIO

® knight -kits ALLIED RADIO, Dep-. 23-G there's a money -saving knight-kit 0. 1)0 N. Western Ave., _hicago 80, III. for every need ...see them all in the j i Send FREE Catalog -eaturing Knight -Kits. ALLIED CATALOG Describes the complete KNIGHT - KIT line in detail. Order the kit FREE Name of your choice-judge quality and value for yourself under ow send Address Free examination privilege! for it ! City lone Sta -e J

19 July, 1960

AmericanRadioHistory.Com Bookshelf THE VERY (Continued Jron1, page 18) FINEST l,. I anyone who would like to have a fuller and J -.. CITIZENS' ~ more detailed understanding of all phases of electronics. RADIO..., W9 `

Tr.

"RADIO CONTROL FOR MODEL BUILD- ric.., from 412975 ERS" by William Winter. Published by Farming, Anyone John F. Rider delivery or can operate-license issued Publisher, Inc., 116 W. 14 St. by FCC on fleet operation request! New York 11, N. Y. 220 pages. Soft cover. 23 channel Class "0" Band coverage -choose 1 of 5 channels by flip of $4.25. switch! Here is a complete guide for the radio- Designed for 10 watts-limited to 5 for Citizens Radio. Excellent receiver sensi- control fan. The author is the tivity editor of and selectivity. Built-in Squelch, Auto- Model matic Volume Control, and Automatic Noise Airplane Car -to -office Limiter. With tubes, or home microphone, and crys- News and he knows tals for 1 channel. communication ' his RADIO CONTROL , Available from authorized Johnson subject inti- Distributors-installation and service mately. Starting at at all General Electric Communica- tions Service Stations. a basic level, he MOOEi. BUILDERS gradually works his . ev w.miwsM, r»,.. r.vsp.. «,. E. F. JOHNSON CO way up to more ad- IBoat -to -boat or 126 Second Ave. S. W. Waseca,Minn. ship -to -shore vanced topics. Fol- communication Please rush me your full color brochure describing the Viking "Messenger" Citizens' Transceiver. lowing an excellent FREE .° NAME_ introductory chap- Color Brochure ADDRESS on WRITE TODAY ter how to get CITY STATE started in radio con-

trol, he discusses ...... a.-. nas- .._." a141 ,..' .-.,.... Enjoy your H/-fl OUTDOORS transmitters, re- . . ceivers, ,.rime:,,.. PATIO, GARDEN, TERRACE, POOL actuators, power supplies, meters, relays, the radio - with the new WT-0 controlled boat, and advanced systems. Highly recommended as a most useful ATLAS HI-FI source of information about radio control. COAX -PROJECTOR all-weather construction... install if, forget M... m ® or fake it with you wherever you listen. "ABC's OF HAM RADIO" by Howard S. True hi-fi TWO-WAY system- Pyle. Published by Howard W. Sams & not just a "compromise." The WT -6 comprises a weather- Co., Inc., 2201 E. 46th St., Indianapolis 6, proof cone type driver (with Ind. 112 pages. Soft cover. $1.50. I 6 -inch throat) coupled to its r1 individual woofer horn; a This 4 sep- simply written introduction to ham arate pressure -type driver loaded to its separate tweeter radio covers the subject from the stand- horn; and built-in electronic point of the complete newcomer. It dis- t: crossover filter. For all indoor and outdoor. cusses how to go about getting a license uses ...universally adjustable and how to learn code. In addition, it pro- 6' "U" type rugged steel mount- %,k ing ... finished in high-tem- vides a brief course in basic electricity and -, perature baked modern beige = enamel. electronics. Recommended to anyone in- Power Rating 15 watts contin- terested in becoming a radio amateur, it uous. Freq. Resp. 125-15,000 cps. Impedance 8 ohms. Ms- would be a fine gift for a youngster. : persíon 120°. Bell opening 15 overall depth 12". See the WT-6 át CD, CD, tD, , your local dis- Net $34.50 trtbutor. Send for catalog 560. "PRINCIPLES OF GUIDED MISSILES AND NUCLEAR WEAPONS," prepared by the ATLAS SOUND CORP. U. S. Navy Training Publications Dept. PE 7, 1449 - 39th St., Brooklyn 18, WY. Center. Available from Superintendent of Docu- 20 Always say you saw it in-POPULAR ELECTRONICS

AmericanRadioHistory.Com 'HE -15 111k0E LAFAYETTE _ -t § CITIZENS BAND 11 METER SUPERHETERODYNE TRANSCEIVER Not)Superregenerative but SUPERHET Planetary Vernier Tuning: Controls include 3 position function switch (transmit, receive, plus transmit with spring COMPLETELY return) and automatic noise limiting switch. WIRED High Output Crystal Microphone: 2 position push to talk slide switch; especially designed for sustained transmit NOT operation with a minimum of background noise. 4.5 Adapts for Use Anywhere: Modern compact styling. Brack- 5.00 DOWN r A KIT ONLY ets are supplied for easy mounting of unit in auto, truck Acdition of 6 or 12 volt power supply (separately Operates at a or boat. 5 Crystal Controlled Transmitting Positions: supplied) adapts transceiver for mobile operation. Only input of 5 watts fully modulated. maximum FCC legal power 41/2"D x 6"W x 4"H. Tuneable Receiver Over Full 22 Channel Superheterodyne No examination or technical knowl- stage in both Transmitter and receiver, 3 watts Anyone Can Operate: Band: RF citizen 18 years or older is eligible audio plus large 4" speaker. edge required-Any output fill out FCC application supplied with Complete with Transmitting Crystal: Removable front plate for a license. Simply for easy accessability of crystals. Channel 9 crystal sup- HE-15 Transceiver. plied. HE -15 Factdry Wired and Tested (Less antenna) 4 Dual Function Tubes, plus 2 Single Function Tubes, plus 2 5.00 Down Net 64.50 Compares with units 3.95 Rectifiers for 12 Tube Performance: HE -19 Whip Antenna Net as much. Unexcelled reception on land and 11.95 costing 3 times HE -16 Power Supply For 12 Volts - Net coverage up to 20 or more miles depending on sea .with Power Supply For 6 Volts Net 11.95 antenna height and terrain.. HE -18

i Boating - Ship to Shore INDICATOR NEW! LAFAYETTE TELESCOPIC NEW! LAFAYETTE RADIO FIELD CITIZENS BAND WHIP ANTENNA A Must For All Ham and Citizens Band Chrome'Plated Telescopes From 161/2" to 40 " Mounts Vertically or - Provides a Continuous indication 7.95 3.95 Rigt Angle of Transmitter Output An outstanding antenna value. This high quality Rugged 200ua Meter Movement antenna is designed - . three section telescoping with Variable Sensitivity Control Q----- for attachment directly to your citizens band. over Requires no Electricity, Batteries transceiver. Ideal for point to point service iL, pmü . short distances. Molded base loading coil has a or Transmitter Connection - r,e T41 threaded stud with a PL -259 plug-connector for vertical or right angle mounting. Shpg. wt; Measures the RF field generated HE -19 Net 3.95 by any marine, mobile or fixed transmitter. Rear phone jack ac- earphones. Antenna ea - cepts mount- LAFAYETTE "Tiny" 6 -Transistor Radio tends from 31" to 103/4". Bottom plate magnet allows ing on any metal surface. Measures 31/a"W x 21/4°r H x 2"D (less a Small Package! Sensational Performance In antenna). Shpg wt., 2 lbs. 4 Plus a 6 Transistors y Net 7.95 Germanium Diode TM -14 Superheterodyne PLEASE RUSH ITEMS CHECKED Circuit Radio Field Indicator Vest Pocket Size- HE -15 Citizens Band Transceiver TM-14 Only 4"H a 2t/a"W x \10; HE -19 Whip Antenna FS -206 "Tiny" 6 Transistor Radio 17/4"D 600 Built In Earphone Jack Free 303 Page Catalog For Private Listening Enclosed Fínd $ Trouble-Free Printed Please include postage to cover shipping Circuit Built-In Ferrite Bar FREE 308 Giant Size Pages Antenna Economical-Uses 1, Name,. Only One 9VoltBattery Address ONLY 19.95 case and earphone. Complete with battery, carrying City Zone State Shpg' wt. 2 lbs. P.O. BOX 222, Jamaica 33, N.Y. Dept. IG-6J FS -208 "Tiny" 6 -Transistor Radio Net 19.95 LAFAYETTE RADIO

21 July, 1960

AmericanRadioHistory.Com Bac,kshelf New York, N. Y. Soft cover. 100 pages. $2.25. (Continued from page 20) This is a very interesting book about the meats, U. S. Government Printing Office, fundamentals of direct current electricity Washington 25, D. C. 284 pages. Soft cover. in terms of the Franklinian Approach-or $2.00. from the point of view that current flows Like many U. S. Government publica- from plus to minus. The illustrations effec- tions, this book is notable both for the tively complement the text, adding interest amount of information it provides and for and clarifying the presentation. Consid- the clear way in which it is presented. erable attention is paid to electrochemistry, Much of the text is devoted to explaining voltage drop, and the magnetic effects of the principles of guided missiles, including electric current. Recommended as reward- systems for propulsion, control, and guid- ing reading for anyone with a basic knowl- ance. This part of the book is jam-packed edge of electronics. with information that should' interest anyone with a mechanical or electronic turn of Miscellaneous mind. Literature The remainder of the work is concerned IÍ A complete catalog of Lafayette audio with nuclear weapons. The section on their and electronic kits has recently been destructive effects is an- absolutely spine -chill- nounced. Write to Lafayette ing; if anyone still believes that nuclear Electronics Mfg. Corp., 104-46 Dunkirk St., Jamaica 12, war is feasible, let him read this hook. N. Y. for this attractive 20 -page booklet.

m "Tape Recording Head Reference Guide," a 16 -page booklet containing specifications "DIRECT CURRENT ELECTRICITY" by and illustrations of tape recorder heads, is Alexander Efron. Published by John F. available for 50 cents from Robins Indus- Rider Publisher, Inc., 116 West 14th St., tries, 36-27 Prince St., Flushing, N. Y. -

REMARKABLE TUBE VALUES AT 1950 PRICES °?/oua.(ie.sl (Ju.f sa : ALL TUBES IND. BOXED, ,. CODE DATED AND BRANDED "TRU-VAC®" Typical TRU-VACS Bargains! THIS IS A PARTIAL LIST TAlwhousays murkMore In 65N7GT ALWAYS 30c 6W4GT ALWAYS 30c 024 7CT5 584 6ASS 6887 6C56 650700 704 774 17827 1916 SOCO 024 364 5U4 6616 681.702 6C15 6555 705 1768 17CA5 1918 l A7GT SAS 5046' SUB 6AU4GT 6BN6 6CU6 6507 786 17465 17C145 74A I BlGT 56 3615 3240 6AUSGT 600601 606 6507 787 11605 1204 IC6 252601 57 36C5 52601 6AU6 6807 60E6 65X7 788 17616 1715 16 1C7 58 3066 508 6A118 6000 600607 6517 7C4 1]617 12K7 114 523 77 71A 3026 646501 6858 6006 6567 7Cí 126116 .1716 3S IFS 6A6 6.626 75 3CB6 66250 615 6517 7C6 11667 1207 35A5 IG4 304 6684 6ÁW8 6826 656 6507 7C7 76 126V6 116A7 7585 77 1H SOT 354 6AC7 6Ax40T 6827 6116 6587 7E5 12A67 17517 35C5 78 114 224 6614 631K5GT 4C4 614 6L4 7E6 11527 35W4 80 116 41307A 6605 6C06 615 608 6UB 7E7 17A47 1256707 3525 16507 858 646407 6846 6C060 636 62601 717 84/624 12627 12507 76 1R5 4827 66114 6BCS 606 617 6W6GT 11717)1723 'Le_12AK4GT... 758 1284 179607 38 155 4CB6 6ÁK5 'BCE 6CG7 66601 624 707 11866 114 1252407 70/44 SA/68 6415 6806 6CNB 6K7 64507 7117 12867 1114 12Ka 1 For any used SANG 6ÁM8 60E6 6C16 6X7 646 7647 12606 1US 14A7/1787 SA18 6ÁN8 6685 6CM6 607 6266 707 12016 1V2 1486 42 SAVE 6605 68060 eCM7 654 764/x)t5 757 120,6 162 8407 42 or factory second tube! 5624 6606 6006 ¿CO? 657 7AS 746 12BN7 19 AS 74,4 SORB 6607 6816 6COB 65807 766 767 12806 2064 19611407 50A5 516 OARS 6865 6CR6 6567 767 724 12807 198060 SOBS c11araUSEDeed CONSOLES 1 YEAR GUARANTEED p ' PICTURE TUBES & Work 51'he17"When Brand New. Allied A-1 Tubes New 14" .. $29 Receive Below Listed do not include dud. grand IG Them erices Add Additional 56.00 Deposit n tube sizes to 20': 19" on 21' and 24 tubes -57.50. Deposit ielunded immediately when dud Is returned prepaid. 20".'2137 Aluminized tubes -54.00 extra. An sets Picture tubes shinned only to continental USA and Canada-All F.O.B. N. J. 9e. Sets ed in two tubes Harrison. antl CSets s Only d ) 97 avoid 17Ce4 I n, u n 116199 1,r DM lug 31 ll 1139 onl 108/4 1049 1/0141 100 1181 116641 7.19 21x94 1 U.S.A. 11.99 1469 FREE New 141/C14 171114 1 160,4 1319 11694' 479 11/914 7139 414 39!: BON Jersey. 16604 199 609 11,94 1::: 701114 17, 14791 19.79 ]0417,11 FREE with US--RABBIT 11019 17.19 17Áv16 1199 17019 11.69 21614 71 99 14 17.99 74094 7X9 each EARS I1G 14 1607 1/ 4 21 e 9 1Á4 set 17119 u 211/9 1161,16 4 17.49 purchased ATTENTION QUANTITY USERS! , Bin Diseounte Are You:r... 1Cu7 11 or 1 Write For Our $ 7.95 1000 Tube "Private Label" Sneoinl! Attention Rrandlne Dent. BI GR. Money cheerfully refunded within five (5) days. if not completely satisfied! Value TRU-VAC® PAYS YOUR POSTAGE on orders of $5 or ore in U.S.A. and Territories. Write For GUARANTEEare Send approximate no tae, on Canadian and lennon orders. Any order Iran $5 On Y 7011NÁ0.' 25e than require. FRE LIST - rep ? bondline char.,. Send "-fi ú on C.O.D.'.. All orders subject 111 h Complylnz to prior sal0. Of TuEbes d nt0easny ttubc 1rit1. Federal rre Intione. the folloll'loe 11 Tru-Vne iOrfe irF statement runlet,*( adver- Products Sold d eter twhae tie t1: Tubes onpeorinl 10 this ad may be FACTORY and are óales FUSEE SECONDS or USED tubes Oy TRU- CLIPI 1,FREE e y marked. ,ht" VAC® P1rc OL' of 5Ay y Or Mori. Vint Ow Ol Electric Company Hugs Testing Dept. In The Heart .:T Harrison. N. J:6 Ele

AmericanRadioHistory.Com CONVERT YOUR CAR RADIO FOR SHORT WAVE RECEPTION WITH...

INTERNATIONAL'S ALL TRANSISTOR, CRYSTAL CONTROLLED CONVERTER

Now, in a matter of minutes, your standard International Mobilettes cover these short wave bands. broadcast car radio becomes a short wave Catalog No. Frequency receiver ... bringing in stations from coast - 630 - 105 75 meters (Amateur) to -coast as well as the four corners of the 630 - 104 40 meters (Amateur) globe. 630 - 106 10 MC (WWV Time Broadcasts) Designed by International for AMATEURS, 630 - 103 20 meters (Amateur) CITIZEN LICENSEES, SHORT WAVE LIST- 630 102 15 meters (Amateur) ENERS, HOBBYIST. - 630 - 101 11 meters (Citizens) Available in SEVEN frequency ranges cover- 630 - 100 10 meters (Amateur) ing the Amateur bands, 75 through 10 meters, 28,5-29.5 MC Mailable soon for 6 and 2 meters the Citizens band, and WWV National Bureau at slightly higher price. of Standards Time Broadcasts. Three simple steps to install. (1) Remove a _ -*AlfAlft . antenna lead from car radio and plug into input of Mobilette. (2) Plug jumper wire from Mobilette into antenna connection of car radio. (3) Plug power connector into cigarette lighter It's that Complete, ready to plug socket. easy! in and operate ... only $19.95 Works on either 6 or 12 volts without change. Order direct from International. Terms F. O. B. Miniature size. Okla. City. Include postage. Shipping Weight 2 lbs.

INTERNATIONAL CRYSTAL MFG. CO.. INC.. IS NO. LEE T -"'-iY i OKLAHOMA CITY, OKLAHOMA Is GYi ; GENTLEMEN: PLEASE SHIP THE FOLLOWING MOBILETTES C I ` 519.95 EACH. CATALOG NO. FRED. QUANTITY 1 TERNAiriÓ ¡NIA L SHIP TO - NAME CRYSTkL MFG 'é,ó5()_-) NC. AMOUNT ADDRESS ENCLOSED 18 NORTH LEE - OKLA. CITY, OKLA. INCLUDE POSTAGE WITH ORDER.

July, 1960 23

AmericanRadioHistory.Com CITIZEN BAND CLASS "D" CRYSTALS TEXAS 3rd Overtone: Hermetically Sealed .00500 tolerance-Meet F C C regdire- HC6/U ments, t/a" pin spa ling-.050 pin diam- eters. (.093 pins avail- fallable. add 150 perrrys. ALL 22 FREQUENCIES EACH products IN STOCK! (add Se per crystal for postage and handling) STEREO CARTRIDGE The following Class "0" Citizen Band frequencies in The Norelco Model AG3400 stereo car- stock (frequencies listed in megacycles): 26.965, 26.975, tridge 26.985, 27.005, 27.015, 27.025, 27.035, 27.055, 27.065, employs the moving magnet principle 27.075, 27.085, 27.105, 27.115, 27.125, 27.135, 27.155, and features 27.165, 27.175, 27.185, 27.205, 27.215, 27.225. high vertical Mulched crystal sets Coy Globe, Gooses. Citi-Fone and Ilallitrafters Units . . . 55.90 per set. Specify equipment make. compliance RADIO CONTROL CRYSTALS (3.5x10 -'cm/ w in HC6/U HOLDERS-SIX FREQUENCIES In stuck Ior Immediate delivery lfre,luencie,, Ilsled iii ,n gn- dyne) and high I eleH1: tolerance .005%. n mating. .0:'0 Inn iaeter. o 1,0'.13 pins available. arid Iuo crystal.1 dm desired. per Specify I, ognency output (30 milli- ate C z 26.995, 27.045, 27.095, 27.145, volts per chan- 27.195, 27.255 $29 5 EACH (add nel) . Frequency Sc per crystal for postage and handling) s1,1**" Send for FREE CRYSTAL CATALOG #860 response is vir- WITH OSCILLATOR CIRCUITS tually flat. from ASK YOUR PARTS DEALER FOR TEXAS CRYSTALS

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AmericanRadioHistory.Com products (Continued from page 26) marketed by Sidco, Box 312, Venice, Calif. Constructed of nylon, the handle is air- cooled and does not require a cork grip;

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r . xI 1. , KITI OF _ : ll " 00 . .. sy rr1bol of Bi-Pass . ., . a oyCONDENSERS. .1 r - RA_D-TEL Are 6110V -`_}w " aLaH Q THAN 4e each " 0 0 oft o _: _ o g .Sm ir" Molded { tll' ta .Paper and MYLAR ) atua } Y;, QuALITY , _ t Made up of approa. p ! INSIST ON RAD-TEL FOR EVERY 16.200V. 20.400V -- TELEVISION AND RADIO TUBE NEED and 64-600V. ,_- -.001 to ,. BONEFizz 70% OFF- ón '`BRAND NEW =TUBES - YEAR! o .You.4º:Cán Rely ,On Rad-Tel's Speedy One Day, Service! Not Used Not Pulled - Out Of Old Sets Each Tube Individua ly and Attractively Boxed! sty. Type Price Qty. Type Price Qty. Type Price Type Qty. Price Qty. Type Price Qty. Type Price Qty. Type Price -_OZ4M .79 _4827 .96 -6AV6 AD _ .6DE6 .58 _ _12ÁE6 .43 - _12CR6 .54 -1704 B9 _1A :K2 .62 _ _4CS6 .61 __68W8 .89 _ _6066 .59 _ .12AF3 .73 _ _12C115 .58 ' -11330T .79 __4016 ___17006 1.06 .62 ___6844 .65 __6006 1.10 _ _12AF6 .49 - _12006 1.06 _10 95 .55 _ _40K6 -1716 58 .60 _6AX7 .64 _6DT5 .76 ...._12A16 .46 _ _12CXE .54 __17W6 -1G3 .73 _ _4016 JO .55 -_6BA6 .L9 _._6016 .53 _.12815 .45 - 12065 .69 _19804 -113 .73 53 ___5AM8 .79 ___68C5 _ .54 ..6E08 .79 _ _12A18 .95 ___120E6 .15 _,_.19866 1.39 ¡1 K3 .73, - _5AN8 .86 ._68C7 £4 _ ....6688 .79 _..12805 .52 12013. .35 _1918 90 116 1.05 _ _5A05 .52 __6BC8 .57 _6H6GT .58 .. .12AT6 .43 ....12DM7 .37 __..21E46 _11115 .59 ___58T8 1.49 .80 _ _.6806 .51 __615GT .51 __ __12AT7 .76 _12006 1.04 _ . 25606 1-11 -165 .62 _ .5BK7A .82 _6656 .55 -616 .67 _1206 .50 _._1205- .79 - _25C5 S3 -155 .51 _ 5607 .97 _...6BF6 .44 _6K6 .79 -12807 .60 __1202E .56 _ _25C115 .59 il _174 .58 _ _58R8 .79 __6866 1.66 __6S4 .48 .___12ÁV5 .97 _._12316 .50 ___25CD6 1.14 __11.14 .57 _ .5CG8 .76 _ _68116 .65 -6SA7GT .76 -12AV6 .41 __12EGE .54 _25CU6 1.11 -1115 .50 5018 .76 _.68H8 - .87 -6SK7GT .74 __12AV7 .75 -_12EZ6 .53 ___25DN6 1.12 _1X2B .82 _._5E48 .80 ___61316 .62 __6S17 .80 _12AX4 .67 __12F5 .66 ___25EH5 .55 -2AF4 .96 __ 5E118. .80 __613K7 .85 _6SN7 .65 _12AX7 .63 _._12F8 .66 _ _2516 .57 _2CY5 .71 - 516 .68 -__6617 1.00 -6507 .73 ._12427 .86 -_12FM6 .45 _.__25W4 .38 -_3A15 .42 -_5T8 .81 _-68N 4 .57 ..._614_.99 __1284 .63 -_12K5 .65 _25Z6 .36 ___.3AÚ6 .51 - 504 .60 _68416 .74 __6U8 .78 __1213A6 .50 --12SA7M .86 _ _35C5 .51 _3AV6 .41 _ .508 .81 -6805 .65 -.6V6GT .54 ___1213D6 .50 -_12SK7GT .74 __3516 .57 _ 3EA6 .51 _5V6 .56 a _6806GT 1.05 .75 __6W4 ___128E6 .53 -.12SN7 .67 _.. 35W4 .52 -3EC5 .54 -5X8 .78 ._6807 .95 _...6W6 .69 _126F6 .44 _12SQ7M .73 _. _3525GT .60 -_36E6 .52 -5Y3 .46 __6BR8 .78 -644 .39 12BH7 .73 1207 .62 .5085 .60 -3B416 .76 _6AB4 .46 --HUB .70 - _6X5GT .53 ..... 12B16 .56 -.12V6ST .53 __5005 .53 -_36U8 .78 _.6ÁC7 .96 .__68Y6 .54 _6X8 .77 __12606 1.06 ____12W6 .69 _ 50DC4 .37 -3BY6 .55 -.68F3 .73 __6826 .54 _..7807 .61 _._12BY1 .74 _._12X4 .38 .50EH5 .55 -_3616 .55 _6ÁF4 .97 .__6827 .97 __7A8 .68 -_12BZ7 .75 __178X4 .67 _..5016 .6.1 _3CB6 .54 _6ÁG5 .65 __6C4 .43 .766 .69 _ _12C5 .56 _..17805 1.09 117Z3 .51 _3CF6 .60 -6AH6 .99 .6C86 .54 ._7Y4 .69 _12CA5 .59 __17C5 .58 __3CS6 .52 68K5 .95 - ___6006 1.42 __.8ÁU8 .83 _ . 12CN5 .56 _ ..17045 .62 _3CY5 .71 _6AL5 .47 ___6CF6 .64 _._8ÁW8 . -__3D86 .60 __6AM8 .78 ___6067 .67 _...8605 .60 __3D16 .50 _ _6AN4 .95 _ .6068 .77 __8CG7 .62 TRANSISTORS _305 .80 6AN8 .85 _ _6CM7 .66 .68 ` a __8CM7 lCBO 6V 1E80 7 3J hFe ckt A _354 .61 _ .6805 .50 _ 6CN7 .65 _8CN7 .97 ' ' ___3V4 .58 10 pa max. 10 pe mar. _ .6AR5 .55 _ _6CR6 .51 _ _8C413 .93 25 mir. _4BC5 .56 In, _6AS5 .60 _ .6CS6 .57 _.._8EB8 .94 _4BC8 .96 a IN LOTS OF 10 6AT6 .43 __ 6C U5 .53 _.._10DÁ7 .71 a , _48N6 .75 _6ÁT8 .79 _ 6CU6 _....11CY7 .75 -4EQ7 .96 6AÚ4 1.0.3,,,,c,,,,,T o. 11111 - .82 .6CY5 .70 ___12A4 .60 .147-1_ -4ES8 .98 _ _6AU6 .50 _ 6CY7 .71 _ ..12 .55 II, 'n"" W" _ 8 "" 4E U8 .71 . _.6AU7 .61 __OM.405 .68 __._12AC6 .49 _4BZ6 _ .58 - _6808 .87 6DB5 .69 . .12806 .57 General: purpose Type EA, SEND FOR FREE TROUBLEI SHOOTER GUIDE AND NEW TUBE & PARTS CATALOG. ' e 55 Chambers St l II 'i Newark 5, N. J. PE-760 1 =TERMS: 25% depositIIIo° must accompany .$1 all orders - balance C. O. `D Not Affilicited With. a -HANDLING CHARGE FOR ORDERS UNDER - $5. Sub-ect to° prior sale. Any Other Mail ,. Please add postage. No C. O. D_'s outside continental, U_ S. A_ . Order Tube Co. July, 1960 33

AmericanRadioHistory.Com mounting the batteries on a small wooden Tips base with thumb tacks, wood screws, or cellulose tape. Make the leads more com- and pact by curling them around a stiff wire AV and then withdrawing the wire. Solder each Techniques lead to a medium -size (34" -long) Fahne- stock clip screwed to the wooden base. The

TAPE MOUNTS CAPACITOR Need a mounting bracket for an electrolytic capacitor? A band of electrician's plastic tape will serve the purpose. Wrap

-7[ , :.P!'. 1 positive (red) terminals can be labeled with a ball-point pen.-Art Trauffer, Council Bluffs, Iowa.

MAKE YOUR OWN QSL CARDS You can make an inexpensive and artis- tic QSL by drawing a sample of the desired a short length of tape around the capacitor, card to size, in India ink, on a sheet of and leave a small tab extending from the white paper or cardboard. Take this black body of the unit. Punch a hole in the tab and white "master copy" to a photo -finish- and mount the capacitor with a screw and ing shop and have a negative made. Prints nut. John A. Comstock, Wellsboro, Pa. can then be ordered on heavy postcard size paper imprinted with a standard postcard SPOOL HOLDS WIRES FOR SOLDERING form on the reverse side. (The negative can Your solder spool flange can be used to be copied at home if you have printing hold wires and parts while you solder them. equipment.) Color the finished postcard Hacksaw a couple of "V" shaped slots on prints with photo -tinting solution.-Glenn P. Pittsley, Fayetteville, N. C.

WALL SWITCH SAFETY LOCK When working on electrical equipment controlled by a distant switch-basement lights and attic fans, for instance-you can use this safety "lock" to protect yourself from accidental 14; electric shock. Take an ordi- opposite sides of one flange. File off any nary 11/4" -wide burrs or sharp corners on the cut edges and spring -action slip in the wires to he soldered.-Joseph paper clip and Carroll, Brooklyn, N. Y. attach a "hands off" sign to it as PROTECTING SUN BATTERY LEADS shown. Clip it Ii r N D S OFF. Sun battery leads are fragile and often on the switch break off during experiments. Since they lever controlling the device you are about are difficult or impossible to repair, try to work on. This makes it impossible for 34 POPULAR ELECTRONICS,

AmericanRadioHistory.Com CREI has developed a program of home study that is .comparable in technological content to advanced residence courses in electronics. The program was developed hand -in -hand with For serious- leading companies and Government agencies contributing to the Nation's efforts in electronics, communications, missiles, minded men and space exploration. This CREI program in Electronics Engineering Technology may be completed in 2 to 4 years, depending on how much of your spare time you can devote to study. The courses are desiring presented in easy -to -understand form. Our instructors will give you personal attention and assist you when you need help. higher To qualify CREI graduates for advancement to key technical positions, CREI offers a complete program in electronics, including- income and Automation Instrumentation Industrial Electronics Aeronautical Electronics Guided Missiles Radar Servo -mechanisms Computers Astronautics Tele - status- metering Communications Electronics Manufactur- ing Field Engineering A COLLEGE -LEVEL EXTENSION PROGRAM IN ELECTRONICS There is a drastic need in the electronics industry for well- educated engineers and technical personnel. Although the CREI's Extension Division great majority of students find ample opportunity for advancement with their present companies, CREI maintains a Placement Bureau to assist graduates and advanced stu- offers you a college -level dents in finding more desirable positions. For many years, the demand for CREI graduates and advanced students has home study program in far exceeded the supply. A few of the private companies and government agencies electronics comparable in whose officials approve CREI for their own personnel: U. S. Navy (5,240 enrolled in Florida Power & Light technological content to extension program) Pan American Airways Army, Air Force, Marine Corps, Coast Guard United Airlines advanced residence courses. The Martin Columbia Broadcasting System Company All America Cable & Radio National Broadcasting Company Voice of America Federal Electric Corporation ... and many others QUALIFICATIONS FOR CREI. You qualify if you have a high school diploma or equivalent, and if you have had basic electronic training and practical experience in electronics. Available to Veterans. Mail this coupon ... today!

CAPITOL RADIO ENGINEERING INSTITUTE To obtain ECPD Accredited Technical Institute fast, immediate Curricula Founded 1927 service and to avoid delay, Dept.1207-G, 3224 16th St., N.W., Washington 10, D.C. Please it is necessary that the fol- send me your course outline and FREE 44 -Page Book lowing L"Insurance for Your Future in the New World of Electronics" information be filled describing opportunities and CREI home study courses in: in Advanced Electronic Engineering Technology. Employed by Radar, Servo and Computer Engineering Technology Check field o Electronic Engineering Technology of greatest Communications Engineering Technology Television Engineering Technology Type of Present interest Aeronautical Electronic Engineering Technology Work o Automation and Industrial Electronics Engineering Education: Technology Years of High School Name Age Street Other City Zone State Electronics Experience Check: Home Study O Residence School p Korean Veteran

July, 1960 35

AmericanRadioHistory.Com sufficient wattage rating to handle the drill's current safely. To obtain the wattage (Continued from page 34) rating of your drill, multiply its current anyone to snap on the circuit accidentally rating by 117 volts. Don't operate your without first removing the paper clip.- drill on higher line voltages continuously George P. Pearce, Albuquerque, N. M. for any extended periods as this might damage the motor.-Jerome Cunningham, Chi- TRANSFORMER SELECTS DRILL SPEEDS cago, Ill. To obtain a variety of speeds from your electric drill, use an isolation transformer DON'T "VISE" THAT DRILL with adjustable output voltages. By setting Never clamp your electric drill directly in a vise in an effort to replace a horizontal drill stand. You could very easily tighten the vise enough to crack or cave-in the drill's case and cause it to rub against the motor armature. Instead, take a thin 41''., piece of scrap the transformer switch for an output above aluminum, about 2" x 12", and wrap it or below the normal line voltage, drill speed tightly around the drill. Clamp the ends of can be changed several hundred rpm, up the aluminum strip in the vise.-Charles or down. Be certain the transformer has Lang, San Francisco, Calif.

'Build the Best CITIZENS BAND TRANSCEIVER E/COQ, *760 (117 VAC) less hracket: Kit $59.95: Wired $89.95 *761 (117 VAC & 6 VDC): Kit $69.95. Wired $99.95 *762 (117 VAC & 12 VDC): Kit $69.95. Wired $99.95 Highly reliable; exemplary electronic, mechanical, industrial design. Powerful 5 -watt (as defined by FCC) crystal -controlled transmitter & extremely sensitive, selective superhet receiver with RF stage & noise' I miter. Built-in speaker, detachable ceramic mike. Pre-set & sealed crystal oscillator circuit elements. - To change channels, just change crystals - no adjustments ' 41 needed. Built-in variable "pi" network matches most popular .,O antennas. Portable whip & roof antennas available. No exams tf or special skill needed any citizen 18 years or older may obtain station license by submitting FCC form, supplied free by EICO.

90 -WATT CW TRANSMITTER* #720 Build the Best 6 -TRANSISTOR RADIO RA -6 Kit $79.95 Wired $119.95 Kit $29.95 Wired $49.95 tÁd 'U.S. Pat No. D-184,776 includes FET, less 9V battery ttt. "Top quality" - ELECTRONIC KITS GUIDE. High sensitivity & selectivity. New plug-in ,'s Ideal for veteran or novice. 90W CW, 65W Big -set volume & tone: 4" type transistors. external plate modulation. 80 through 10 o 6" speaker; push-pull audio. Built-in Fer- ,..i' meters. rite rod antenna. Pre -aligned RF & IF transformers. Planetary vernier tuning. Earphone jack for private listening. Attractive tan HIGH-LEVEL UNIVERSAL leatherette case, retractable handle. Com- MODULATOR-DRIVER #730 lbs. pact: 81/2" w, 41/2" h, 21/2" d. Only 3 Kit $49.95 Wired $79.95 Cover E-5 51.50 Buifd,thé Best -Ham Gear undistorted audio. Modulates t> .1.12. Delivers 50W .. transmitters having RF Inputs up to 100W. New Code Practice Oscillator #706 Unique over -modulation indicator. Kit $8.95 Wired $12.95 Rugged battery -operated transistor oscillator GRID DIP METER #710 circuit, built-in speaker. Front panel has Í flashing light,'phone jack, pitch control (500- Kit $29.95 Wired $49.95 2000 cps), external key terminals, "tempo- Includes complete set of coils for full band rary" key. Panel switch selects Tone, Light, coverage. Continuous coverage 400 kc to 25u or both Tone & Light. 61/2" h, 314" w, 214" d. mc. 500 ua meter.

Add lvd in the. West &1960 Compare - judge for yourself - at your neighborhood EICO dealer. For FREE catalog on over 70 models of 3300 N. Blvd.. , L. I. C. 1, N. Y. easy -to -build professional test instruments, hi -ti and , ham gear, fill out coupon on Page 38

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EVERYTHING YOU WANT IN A QUALITY CARDIOID MICROPHONE introducing the ... AND THEN SOME! Compact size ... modern design .. . world's smallest wide response . . . superior feedback suppression ... uniform cardioid pattern ... ruggedness ... reliability; you cardioid dynamic name it, SHURE has designed it into the dramatic new Unidyne III. microphone 50°% SMALLER - Less than 6" x 1'A", 0.6 lb.! PERFECTION IN PERFORMANCE- moving coil design with truly uniform cardioid pick-up pattern. Response: 50 to 15,000 cps. Up to 75% greater distances from sound source. Impressive feedback suppression. l\iDY\F MAXIMUM VERSATILITY - unobtrusive size, dual impedance, light weight, in- by stant change from stand to hand, and wide -range response make it ideal for faithful reproduction of voice or music, SH U R E indoors or out, for P.A., tape recording ... anywhere fine quality is required. RUGGED AND RELIABLE-Famous $5000 SHURE quality. Takes 6 -foot drop - tests and still performs according to Professional Net specifications! Literature available: SHURE BROTHERS, INC. 222 Hartrey Ave., Evanston, Ill. July, 1960 37

AmericanRadioHistory.Com Listen to the EICO Hour, WABC.FM, N.Y. 95.5 MC, Mon. -Fri., 7:15.8 PM, & Sat. 11-12 PM.

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See Page 36 for the BEST BUYS in CITIZENS TRANSCEIVERS, "HAM" GEAR and TRANSISTOR RADIOS. 38 Always say you saw it in-POPULAR ELECTRONICS

AmericanRadioHistory.Com =:7 A<; : -, ---7.--- _-== _, ;-ti.R .-_...... 44;i4 y Operation -: .-,Z ~.....-.,a,..,..- .l. - 1..,v1.K-+z+ _ G 9 , . . . , Radia '...

f L. .:.,- , e- w.nn-r Control .

Engineers at ITT

relax and have fun with radio -controlled

, rY model boats and planes 1

N a lake near Nutley, New 0 Jersey, a model aircraft carrier backs slowly out from shore, swings around, and majestically sails away. Accurately detailed down to the planes on its landing deck, the miniature craft responds to every electronic command from shore. A few miles away, a model plane climbs into the air. It cir- cles, goes through a series of ac- robatic maneuvers, and finally comes in for a perfect landing. Again, its every action is con- -' trolled electronically from the ground. These scenes are duplicated countless times on any sunny weekend from Maine to Califor- nia. But the enthusiastic electronic hobbyists that control their models near Nutley, N. J., are unique in at least one way. Dur- ing working hours, they design and develop some of Uncle Sam's most complex electronic hardware. All of these men are employed in International Telephone and Telegraph's electronic de- fense research Technician William Hudson puts his beauti- laboratory. Their fully detailed aircraft carrier through "ts paces. July, 1960 39

AmericanRadioHistory.Com crazy over

Designer Seymour Glassner has a mighty serious look on his face when he's behind his drafting board (below), but when he prepares to launch his model freighter (left), he breaks out in smiles. e The freighter's hull, by :' the way, sports 15 alternating layers of lacquer and :x elbow grease. Although the a,`_ ship looks almost perfect, Seymour says he will put another year's work into it. In the meantime, it's fully seaworthy, and Seymour enjoys sailing it.

C.:

jobs entail work on radar, satellite tracking - and communications equipment, navigation 7. aids, and htish-hush electronic counter- measures gear.

Since they are engineers, technicians, and 10- 9 designers, most of the ITT modelers have - greater technical knowledge than other hobbyists. But they still run into problems with their R/C boats and planes. t_ One day last summer, for example, technician Dick Lachenauer wished he had never heard of radio control. It all began when he tried to he helpful. A small boy's boat had drifted out into the middle of a lake, and Dick sent his radio -controlled tug out to nudge it back in to shore. Ap- parently the tug nudged it a little too hard, because the boat sank! Dick ended by rolling up his trousers and going wading. But, as with most modelers-and particularly with those who have been bitten by the radio -control bug-such minor difficulties are quickly forgotten. Not long ago we went out with the I s T radio -controllers and came back with these pictures-which prove that electronic hobbyists, he they amateur or pro, have more fun than the proverbial barrel of monkeys!

40 POPULAR ELECTRONICS

AmericanRadioHistory.Com model boats...

, ,Jr r -,' 017 Y, r ' -..,

k ' -`s 4f; '-``

Senior technician Richard Lachenauer -called "Cap'n Dick" by the boys-is equally at home when checking out a Loran -C navigations simulator in ITT's avionics laboratory or designing control systems for model boats.

After making some control adjustments, John DiCiccio carefully fits the superstructure back onto his sleek model cruiser. If you look closely, you'll see scale - sized passengers on the deck. This cruiser, like most model boats, is driven by an electric motor. But at least one craft in the ITT fleet is powered by a gasoline engine, and one ,. 1 goes still further toward realism ;..! with a miniature steam engine. "`-'::-,1e;w ' `", ® +dig 7 .ws. .

July, 1960 41.

AmericanRadioHistory.Com ... and model planes, too!

2 . off she goes! Chuck does the launching himself; a friend handles the controls until Chuck can get back and take over.

:.1

1 Engine's revving up just right . . . the

radio gear's all checked out . so .

KINGPIN of the ITT modelers' "airborne division" is veteran radio -control enthusiast Chuck Kenny. The possessor of college degrees in both electrical and mechanical engineering, Chuck specializes in packaging- . that is, cramming more and more parts into less and less space. Like most of the other ITT modelers, Chuck designs and builds most of the 27.25-mc. control gear used in his planes. Here are some recent shots of Chuck and one of his planes in action.

The launch was successful A o i1 3 and the plane is climbing steadily now. Looks like it's going to be a good flight.

A few minutes later, Chuck 4 takes over the controls and puts the plane through a series of fancy aerial acrobatics.

42 POPULAR ELECTRONICS

AmericanRadioHistory.Com Reflex and

regenerative circuits !+s y. are combined

in this sensitive

and stable .. .

TRANSISTOR POCKET RADIO 111.,, á _

DESIGNING and constructing a one -transistor pocket receiver is a challenge to any experimenter. A good many "pocket" receivers are either too large or too bulky for true "pocket" operation. Or they simply don't possess enough sensitivity and gain to pull in stations without an external antenna. The little receiver described here gets around both of these weaknesses. It uses a combination of reflex and regenerative action to cut size and components to a mini- By mum and increase sensitivity to striking proportions. The ALVIN MASON complete unit measures only 4" x 21,2" x 3/4". And it's powerful' enough to pull in every local station on the dial with no external antenna at all! Reflex Circuit. Because of the "reflex" action .of the circuit, a single transistor is made to amplify the signal twice-once at radio frequencies and again, after detec- tion, at audio frequencies (see "How It Works"). To simplify the circuit, a diode is used as a detector, leaving

July, 1960 ,43

AmericanRadioHistory.Com the transistor free to do nothing but am- the fact that, once adjusted, the set is as plify. stable as most non -regenerative detectors. Also acting to increase the circuit's sim- Although a Philco r.f. transformer was plicity and stability is the regeneration used as TI in the model, this particular hookup. The circuit is designed so that the transformer is available only from author- amount of positive feedback or regenera- ized Philco distributors and may prove hard tion doesn't control the overall sensitivity to get. However, Ti is in no way critical- as is usually the case with regenerative de- a number of transformers were substituted tectors. What's more, there is no regenera- for the Philco unit, and most of them tion control or annoying oscillation to con- worked satisfactorily. tend with. The Argonne AR -162 (available from Since the remarkable efficiency of this Lafayette Radio, 165-08 Liberty Ave., Ja- little set doesn't depend on regeneration maica 33, N. Y., for $2.95) seems to be a alone, only a limited amount of regenera- good substitution. A miniature output tion is used. Its stability is evidenced by transformer measuring only 1" x 74" x 3/4", the AR -162 has identical center -tapped ,m,,-,,,,,,,,,,,,,,,m,,,,,PARTS LIST primary and secondary windings of 500 BI -15 -volt battery (two Eveready 404E's or ohms with a d.c. resistance of 18 ohms. equivalent in parallel) You'll have to remove the transformer's CI -365-µµt. variable capacitor (Lafayette MS -495 or equivalent) strap and laminations to fit the unit in the C2-/O-Ø., 25 -volt miniature electrolytic capacitor small plastic box specified in the parts list. C3-30-µ1., 25 -volt miniature electrolytic capacitor But you'll find that this bit of disassembling C4-.0005-µ1. ceramic capacitor proves no problem C5-.01-µ1. ceramic capacitor (see illustration on next C6-Gimmick capacitor (see text) page). The windings are light enough to be DI-IN60 diode held in place with a strip of transparent LI-Antenna coil for Cl (Superex 2004 or equivalent) tape. The center -taps are not used. L2-Six turns of #26 insulated wire wound on Construction. The chassis is a piece of LI (see text) Formica or phenolic board about 4" x 21/2" x Q1 -2N78 transistor M6". R1-10,000 ohms Depending on the size of the compo- R2 -2Z000 ohms S All resistors nents, the chassis should fit into a small watt R3-S60 ohms 1 1/4 plastic box measuring about 4" x 21/2" x %". R4 -10,000 -ohm volume control with s.p.s.t. Homemade printed circuitry switch SI (Lafayette VC -28 or equivalent) was used on Sl-S.p.s.t. switch (on R4) the model, but standard wiring will do T1-Coupling transformer (Philco 32-4763-2 or just as well. Most of the component leads equivalent-see text) are long enough to permit point-to-point 1 -2000 -ohm impedance earphone (Lafayette MS. 368 or equivalent) 1-Transistor socket 1-4 x 21/2" x 3/4" plastic box 1- 1" x 21/2" x 1/16" phenolic board Misc.-Tuning dial, knob for volume control, wire, solder, etc.

mumnnnuummmmmundmmmumumummuummuuunmummimmmmm

One transistor does the work of two in this highly efficient circuit. The signal is amplified twice-once at radio frequencies and, after de- LI L2 COLON SOT tection, at audio frequencies.

TO RI TO OI BASE TI TO B - BOTTOM VIEW 44 POPULAR ELECTRONICS

AmericanRadioHistory.Com ci u

I 41.

f t t t C2 ,Rl. C'4 DI 77-."15.3 p/I Eorphomt-f

Parts are mounted on a phenolie bóard f'R2 and C6 éré ore reverse side.

, ,. wiring, but a transistor socket was used .,,,,,,,,,,,,,,,,,,. HOW IT WORKS to prevent possible damage to the transis- One transistor and one diode are employed in a circuit that combines the advantages of both reflex tor when soldering. and regenerative action. Because the signal passes Coil L2 consists of six to nine turns of through transistor Q/ twice-once as r.f. and once No. 26 insulated hookup wire wound on as al. the transistor is prrperty described as operating in a "reflex circuit. Adding to the already high the "ground" end of LI and spaced %/1,,," efficiency of this circuit is the regeneration furnished from it. "Gimmick" capacitor C6 is made by gimmick capacitor C6. lengths of insulated hookup In operation. the r.f. signal picked up by antenna up of two t/" coil L1 is tuned by coil -capacitor combination Ll-Cl wire twisted together several times to form and induced into secondary. coil L2. Fed directly into a small capacitor. the base of transistor 0/. the r.f. signal is amplified and and passed to transformer TI. A portion of the signal It's a good idea to lay out all parts from Ql's collector is returned to Q/'s base by capaci- drill most of the holes in the chassis be- tor C'6 to prmidc additional gain through regenera- fore starting assembly. Since the wiring tion. The signal induced in T/s secondary is detected by diode D1, smoothed by capacitor C5, and returned is relatively simple, you should be able to to the base of Ql through volume-control R4 and take your time and do a good job. As with coupling capacitor ('2. any project, time spent in Transistor 01 attain amplifies the signal, this time construction at audio frcqurnccs. 'rte audio signal from Ql's careful wiring will pay off in the long run. collector is led through the primary of TI to the Operation. After all parts have been r.lrphone. mounted and soldered in place, double-check all connections. Now, with the switch off and battery BL in place, plug in the transistor. Turn on the set and rotate the volume control to full on. Select a station, preferably the strongest one on the dial. Listen for distortion. If necessary, either loosen the coupling in capacitor C6 by un- twisting the leads slightly or by snipping off the leads bit by hit until the distortion disappears. Once adjusted, the set should be nearly as stable as the superhet in your living room. And it's a safe bet that in sensitivity tronsr'iormer TI must be a miniature unit will have Coupling and portability this little unit. If Argonne Type AR -162 is used, it can be re- few equals. duced in size by removing the strap and laminations. July, 1960 45

AmericanRadioHistory.Com Build an Ea rphone Booster Amp/iffier

By LOUIS E. GARNER, JR. i

v ,+ _1_ f '

Self-powered device steps up earphone volume

MAGNETIC earphones are a fa- components available through both local miliar item in the experiment- and mail order supply houses are incor- er's world. Beginners use them porated. with crystal sets, one- and two - Construction. Use a clean, hot, well - tube radios, and small transistor tinned soldering iron and rosin -core receivers. More advanced hobby- solder for all connections. The transistor ists use them with, signal tracers, leads should be soldered as quickly as short-wave sets, and possible to avoid overheating; dozens of other units. use your long -nose pliers as This little transis- a heat sink by gripping the torized earphone transistor lead between the "booster -amplifier" joint to be soldered and the will increase the sen- transistor case, and insulate sitivity of any stand- all bare leads with spaghetti ard magnetic ear- tubing. phone. Inexpensive Resistor RI should be se- and easy -to -build, it is one of the lected to match the output impedance of most, useful accessories the experi- the unit used with the earphone booster. menter can own. Only standard Transistor portables will probably re -

POPULAR ELECTRONICS

AmericanRadioHistory.Com quire a 470 -ohm, 1/2 -watt resistor for R1; crystal radios about 47,000 ohms, 1/z watt; vacuum -tube receivers about 100,000 ohms, 1/z watt. Make the battery connections last-note that the terminal strip lug connected to the positive battery terminal is grounded. Be- cause battery life is quite long, the battery can be soldered permanently into the circuit. Avoid heating the battery excessively when soldering, since heat may damage it. IT With the wiring completed, double-check A one -stage resistance coupled amplifier, the ear- possible errors, poorly phone booster uses a p -n -p transistor in the common - all connections for emitter arrangement. The input signal applied across soldered joints, and accidental shorts. And R1 is coupled through d.c. blocking capacitor CI to pay particular attention. to battery polarity. ()I's base. Amplified output from Q1 appears across the magnetic earphones serving as QI's collector load. Operation. To use the completed in- Operating current is supplied from a single IS -volt strument, plug standard magnetic ear- battery, B1; base bias is obtained from the collector im- circuit through resistor R2 which also introduces phones (units from 500 to 6000 ohms inverse feedback to improve transistor interchange- pedance will work with the booster) into ability. output jacks J1 and J2. Next, plug input tip plugs P1 and P2 into the earphone jacks of the unit whose output you want to boost -a crystal receiver, for example. The earphone booster goes on the instant phones are plugged into it; so be sure to unplug the phone from the booster when 401 pNolkl it's not in use to conserve the battery. 30 ° A ?

PARTS LIST, RUBBER GROMMET B1 -1S -volt battery (Burgess Y10 or i equivalent) C1-0.1-01., 200 -volt capacitor 1I, 12-Phone tip jack GROUNDED PI, P2-Phone tip plug THROUGH MOUNTING/ QI-CK722 transistor SCREW R1-See text INSULATED R2-270,000 -ohm, 1/2 - FROM CHASSIS watt resistor 1-31/4" x lye" x 15/e" aluminum box (Bud CU -3001A or equivalent) Misc.-Hardware, S- lug terminal strip, small bracket, grommet, etc.

47 July, 1960

AmericanRadioHistory.Com TV Explores Deep Wells

Watertight TV camera provides "inside" pictures from 1500 feet down

CLOSED-CIRCUIT TV, already at work in factories, banks, hotels, and garages, is now being used to explore the watery depths of wells. A Los Angeles company, Halla- more Electronics, in conjunction with Layne and Bowler Pump Co., has designed a special watertight TV camera that can be lowered into well shafts up to 1500 feet deep. The TV camera is cylindrical in shape and measures about 4" in diameter and 20" in length. It carries its own lighting-three tiny 150 -watt filament -type bulbs, each with - a quartz envelope. Lighting intensity is variable, being controlled at the surface by a Variac. Whatever the camera sees down in the well is viewed on a 17" monitor receiver. During a well survey, photos can be taken of the monitor screen, thus providing a permanent record of the well's condition. The sweep waveforms for the camera are supplied by circuitry in the mónitor and are . carried down to the camera by a multi - conductor cable. The new system has already proven its worth many times. In one well, for example, the bottom part of a pump had fallen ° P e off as ít was being pulled out of the shaft and had become tightly wedged. The cam- This is the custom-built TV era quickly showed exactly how the camera that sends part back pictures from the bottoms of deep was stuck, providing the workmen with wells. enough information to retrieve it. In another instance, a well was not de- livering as much water as had been anticipated. When the camera was lowered to the level at which water had first been located during the drilling operation, a flow water could be clearly of determined by watching the movement of particles floating past the camera. The problem was solved when the camera also showed that layers of white limestone were impeding a full flow of water. Since the system has been in operation only a relatively short time, well drillers expect this new electronic underwater eye to disclose many more deep secrets. 3p 48 POPULAR ELECTRONICS

AmericanRadioHistory.Com r

s "'""L.7".' " }1

wA f, 4.1

--..-,. ,59 By HARRY J. MILLER

Gasoline -operated generator makes the TV system independent of power lines.

Photo taken off mon- I itor shows the metal screening at the bottom of a 200' well.

Here, the impeller of a pump lies at the bottom of a well and impedes water flow.

July, 1960 49

AmericanRadioHistory.Com NEW DEVELOPMENTS IN PRODUCT DESIGN Large -Screen Portable TV THE Motorola "Astronaut" is the first large -screen battery -operated portable TV set to be offered for sale. Com- pletely transistorized, the forty -pound "Astronaut" features a 19" picture tube. A silver -cadmium battery which can be recharged overnight from an a.c. outlet powers the set for five or six hours of operation. Price: around $360.00, including battery.

Swedish Hi -Fi Speaker ONE of the most unconventional loudspeaker systems ever to reach these shores, the Swedish -made Lund 1001 is a two-way speaker with a built-in bass - treble bi-amplifying system. The frequency response of the amplifiers- which operate without output transformers-is adjusted to complement the response of the speakers. The Lund 1001 will be priced for sale in this country at approximately $395.00.

....Radio Hearing Aid

A NEW concept in eyeglass hearing aids, the Telex "Radiant" is a two-piece unit, with a five -transistor miniature radio transmitter built into the earpiece and a one - transistor receiver incorporated into a separate dime -sized earphone. The design of the "Radiant" eliminates all external wires and mechanical connections and reduces acoustical feedback. Price: about $330.00.

50 POPULAR ELECTRONICS

AmericanRadioHistory.Com ir'i

'LIVER wonder what goes on "down below" The long -wave band is only a half -mega- E the standard broadcast band? Most of cycle wide, compared with over 26 mc. for us think of short-wave listening when we the international short-wave bands. Half a think of DX, but there are many diligent megacycle is close quarters in any man's and adventurous DX'ers who find excite- band. But there are many stations that ment in a different world of communica- must operate on these low frequencies, stations. They DX from 540 kc. down to 10 kc. tions which comprise the delicacies of -otherwise known as the long -wave band. "down below" DX'ing. The special "gimmick" on this band is The "rock bottom" of the radio spec- something called "ground wave." Short- trum-below 20 kc.-chatters away with wave stations have it too, but on a small c.w. stations of the U. S. Navy, the British scale compared to long -wave stations. Post Office, the Swedish Telecommunica- Ground-wave signals travel along the sur- tions Dept., the German Post Office, and face of the earth from the transmitting about 101 other outfits. These stations ex- antenna. The intensity tends to drop with tend upwards in frequency to 90 kc. Here distance, but if you blast out with enough they are joined by many of the world's power at low frequencies, you can cover the coastal telegraph stations that contact globe on a ground wave 24 hours a day. ships on international routes. The ships Huge antennas are required for long - themselves start showing up on 130 kc. wave transmission. And tremendous trans- They soon become intermixed with over 85 mitting power is needed to push the ground - European and Asian broadcasting stations, wave signal around the earth. One long - beginning at 150 kc. wave station, operated by the U. S. Navy The next group of stations is by far the in Jim Creek, Wash., puts out a million most popular with long -wave DX'ers. They watts, pumping its signal into an antenna are the zillions of radio navigational sta- that has its supporting wires strung be- tions throughout the world which start tween several mountain tops; its signal popping up around 200 kc. These aeronau- packs such a wallop that it can be heard tical and marine beacons and ranges, op- by submarines 90 feet below the surface of erated by commercial, government, and military interests, send their identifications the water, wherever they may be. rl dab

"listen to hundreds of fascinating stations all over the world on the little-known v.l.f. band

By TOM KNEITEL, WPE2AB

July, 1960 51

AmericanRadioHistory.Com u111.11a11,1x.1111.111x11xixu1Yn,11111x1uu1nu11n1111u.1111in1WYWWnnnWxllnxW TYPICAL LONG -WAVE STATIONS HEARD IN U.S.A.

Kc. Coll Location Kc. I Call Location

14.5 CNM Casablanca, Morocco 98.5 X?M50 Thule, Greenland 15.3 NHB Kodiak, Alaska 98.5 TAB Ankara, Turkey 15.3 NPN Guam, Mariannas Is. 99.55 OEV33 D. Altenburg, Austria 15.3 NLK Jim Creek, Wash. 99.7 DIU Potsdam, E. Germany 15.5 NSS Annapolis, Md. 100.0 CCS Santiago, Chile 15.7 NPL San Diego, Calif. 103.4 NAU San Juan, P.R. 16.0 GBR Rugby, England 103.4 NAU3 St. Thomas, V.I. 16.4 DMA Bonames, W. Germany 108.0 RKA76 Moscow, U.S.S.R. 16.6 NPM Honolulu, Hawaii 110.05 GYP Hong Kong 17.0 NDT Tokyo, Japan 110.15 CQX S. Torne Is., S. Atlantic 17.2 SAQ Varbery, Sweden 110.15 CQZ Lobito, Angola 18.0 NBA Balboa, Canal Zone 112.0 NHY Pt. Lyautey, Morocco 18.0 NPG San Francisco, Calif. 112.E5 GYS Singapore, Malaya 20.27 IDR Rome, Italy 115.3 CFH Halifax, N.S., Canada 33.95 LCA Jeloey, Norway 119.15 NAM Norfolk, Va. 39.35 JJC Tokyo, Japan 119.15 ZSL Capcntown, U. of S. Africa 44.0 VHB Belconnen, Australia 121.0 UBP U.S.S.R. 44.8 GYU2 Gibraltar 122.65 CQF Bissau, Port. Guinea 51.7 XDA Mexico City, Men. 124.75 CTF Flores, Azores Is. 53.0 NUD Adak Is., Alaska 124.75 CTQ Funchal, Madeira 55.5 NPO Manila, Phil. Is. 125.0 HRC Tela, Honduras 58.0 NPC Keyport, Wash. 125.0 STP Pt. Sudan, Egyptian U.A.R. 60.0 KK2XEI Boulder, Colo. 125.0 VPC Pt. Stanley, Falkland Is. 60.0 MSF Rugby, England 125.0 XXA Goa, Port. India 62.0 GIZ20 Rugby, England 125.0 YQI Costanta, Roumania 62.1 ORL48 Ruiselede, Belgium 126.0 UDL3 U.S.S.R. 62.45 SOA7I Radom, Poland 127.0 UCJ Vanavara, U.S.S.R. 63.1 HAB Szekesfehervar, Hungary 131.0 UNA Kherson, U.S.S.R. 63.85 FY03 Paris, France 132.0 RFSO ' U.S.S.R. 65.95 NAW Guantanamo Bay, Cuba 132.0 ULV Faizabad, U.S.S.R. 65.95 PEW Koolwijk, Netherlands 135.0 PGU Pt. Barrios, Guatemala 72.45 EAA Aranjuez, Spain 142.0 UOX Chamidta tvlys, U.S.S.R. 75.6 OXE21 Skamlebaek, Denmark 142.86 UBJ Baku, U.S.S.R. 78.2 GYC Whitehall, England 142.86 UIX Tcheliuskin, U.S.S.R. 78.55 LOF Mar del Plata, Argentina 147.5 WCC Chatham, Mass. 79.0 RET Leningrad, U.S.S.R. 150.0 ZBH S. Georgia Is., S. Atlantic 83.1 OFA83 Nummela, Finland 152.0 YNNA Managua, Nicaragua 85.7 OAZ Lima, Peru 153.0 VWC Madras, India 96.05 H8B Berne, Switzerland 182.0 TFU Reykjavik, Iceland 97.45 GYZ Malta 194.0 ASK Karachi, Pakistan 'Location unknown

so slowly that, even if you don't read c.w., world. Many planes flying international you can log them with one ear tied behind routes also operate on this frequency. your back. All you have to do is jot the In the remaining portion of the "down actual "dots" and "clashes" down on a piece below" band -510 through 535 kc.-there of paper and later decipher them from a are numerous government beacon stations, list of Morse code characters. familiar to the many DX'ers who have Many of the aeronautical stations send wandered off the beaten path with regular weather transmissions in voice at 15 min- "communications receivers." utes before and after each hour. There are DX'ploring receivers that tune down also many airport control towers to be to the 15-kc. sub -basement are inexpensive heard which use voice. At 405 kc., tht navi- and plentiful in the used and military sur- gational stations end and the maritime plus market. They include the U. S. Navy's communications stations again take over. RAK and RBL models and RCA's AR -8510. If you can copy c.w. at any respectable The soldering -gun crowd can build a sensi- speed, you might find more excitement dur- tive 13 -to -550 kc. receiver from plans in the ing a few hours of listening on 500 kc. than December 1958 POPULAR ELECTRONICS. For you'd get from a week of watching TV. receiving, any long-wire antenna will give This is the "International Calling and Dis- dandy results in this range. tress" channel, used by every commercial If, like many. you are interested in the coastal telegraph station, eery Coast beacon stations -200 to 400 kc.-you have Guard and Navy station, and every ocean- a still wider selection of sets to choose going commercial and military ship in the from. If you stick with the low-priced sur -

52 POPULAR ELECTRONICS

AmericanRadioHistory.Com plus gear, you'll find the U. S. Army's low - International Telecommunications Union, frequency beacon receivers quite good. They Palais Wilson, Geneva, Switzerland. Write include the BC 344, 348, 433, and 1206. The directly to Geneva for details and prices of Navy has its own models: the ARB, ARN, their many lists. RAL, RAO, and RAX. There are also avail- Many easily heard U. S. aero beacons and able many used commercial long -wave re- ranges are listed in the bi-weekly booklet ceivers: the Bendix MN -26; Hallicrafters called "Airman's Guide," sold by the Super- S-51 and S -72L; and National's HRO and intendent of Documents, U. S. Government NC -200. Printing Office, Washington 25, D. C. Prices New commercial receivers for the beacon vary from issue to issue-usually ranging frequencies are currently manufactured by between 50 cents and $1.00. Admiral, Heath, LT Labs, Motorola, Na- Canadian aero beacons and ranges are tional, Nova -Tech, Sonar, Zenith, and a host of others. In addition, European manufacturers normally include a long -wave #'N ..71.-. ,,21,¿-,.' ... The author's listening post. His 11111> r. long -wave receiver, an RBL-2, is second from the bottom on the left.

sa - 4

, 9 -

_ !. , 5 1,, ` ' . 's .

_--- , a-.-,.n:... A U. S. Coast Guard radio operators "stand watch" on 500 kc., the Inter- national Calling and Distress Fre- quency, which is monitored by all marine stations and ships at sea.

hand in the majority of "home -type" receivers they turn out. A Of particular interest to the dollar -con- This three-way navigational aid at scious DX'er is an efficient and inexpensive Long Beach Harbor, Calif., transmits low -frequency converter, the TC-1. recently a low -frequency radio beacon in addition a 140,000 by to flashing -candle- developed Boulevard Electronics (1229 power light and blasting on its fog- W. Washington Blvd., Chicago 7, Ill. I. It horn. (U. S. Coast Guard photo) can be connected to the antenna of any good communications receiver' or car radio. given in "Air Navigational Radio Aids," Battery -operated and transistorized, it available for 25 cents (in Canadian funds) tunes from 200 to 400 kc. from the Queen's Printer, Department of QSL's from v.l.f. stations are some - Public Printing and Stationery,. Ottawa, 'thing to try for. Station information is plen- Ont., Canada. Make checks and money tiful, especially from the Secretary General, (Cantin t.ed on page 108)

July, 1960 53

AmericanRadioHistory.Com Build a Picnic Speaker

By LUIS VICENS

JUST "pipe" the output of your car radio into this extension loudspeaker, and you can have pleas- ant background music at picnics and beach parties. The complete assembly costs only a few dollars and takes an hour or so to put together. Basically, the unit is a small PM loudspeaker (about 4") mounted in a box. You'll also need a length of connecting line, a carrying handle, and a sharpened spike for mounting the assembly in the ground near your picnic spread. The extension speaker is hooked up in parallel with the speaker on your car radio. Mount the picnic speaker in an aluminum chassis box about 4" x 5" x 6" or larger (Bud CU -2107A or equivalent). Cut a baffle opening in the box and cover it with grille cloth or screen -door netting to keep careless fingers out. If you prefer to work with wood, you can use a cigar box, lacquered to make it weatherproof. The spike is made from a 28" to 32" length of 9/8" aluminum rod. File one end to a point and thread the other end to accept a mounting nut. A small bracket can be attached part -way down the spike to provide a toe grip for driving the spike into hard -packed soil. Hook up +he extension speaker assem- Connect the picnic speaker's voice -coil terminals bly to your car radio as shown, then to the car radio with about 15 to 50 feet of 117 -volt mount it near your picnic area by driving the aluminum spike into the ground. rubber -insulated "zip" cord. Attach an RCA phono plug (PL1) to the end of the cord, and PIa bring the car radio's voice coil terminals JI 15-50SPEAKER (IN CAR) PLI Out phono jack (JD) LINEIPiECORDORD /t to a matchingRCA

TO AUTO RADIO which can be mounted on a bracket under SPEAKER TERMINALS ~ the car's dashboard. 30-

Metal cleat bolted to rear of unit holds cord in place when the picnic speaker is not in use.

d '-'' m4v. 54 POPULAR ELECTRONICS

AmericanRadioHistory.Com INSIDE the Microphone

PART 1 of two parts

MICROPHONES are transducers-they convert mechanical energy (sound waves) into electrical energy, just as loudspeakers convert electrical energy into mechanical. As a matter of fact, these two transducers-microphones and loudspeakers- are so closely related that, given the right conditions, any dynamic speaker can be used as a microphone and vice -versa. This dual -function use is utilized in intercom systems and is one reason in- tercoms can be produced so cheaply. There are many different types of microphones. Some are rough -and -tough customers that you can drop on the floor with no ill effects. Others are prima donnas that will refuse to work if you so much as sneeze at them (this is literally true in the case of the ribbon microphone). To see why the various types of microphones have the specific advantages and disadvantages that they do, let's start by discussing the dynamic mike, a versatile performer which can be found in use all the way from ham shacks to recording studios. Dynamic Microphones. Since dynamic microphones are similar to loudspeakers in basic theory, they present some of the same design problems. (See Fig. 1.) Somewhat like a loudspeaker, a dynamic microphone tends to have a peak in its mid range because of resonance in its suspension system. This peak, however, can be controlled by providing an empty space behind the diaphragm. The air cavity works to reduce resonant peaks in the same way a properly designed enclosure damps By out a loudspeaker's resonances. Several other small JOSEPH MARSHALL air chambers behind the diaphragm carefully pro- portioned to emphasize or attenuate certain frequencies-are generally included in the microphone's design. The bass response of a dynamic microphone is sometimes extended by building a "ducted port" into the case. This is a hollow tube which permits

July, 1960 55

AmericanRadioHistory.Com STEP-UP TRANSFORMER MAGNETIC GAP

MOVING COIL

DIAPHRAGM PERMANENT MAGNET

SUSPENSION

\ Fig. 1. Construction of a typical dynamic microphone is shown at upper left. Examples of dynamic microphones include the Shure 530 (at left) and the Electro -Voice 635 (above).

the sound to excite a resonant chamber, vibrating the back of the cone in phase with the front and thus producing a greater movement of the diaphragm at frequencies near the chamber's natural resonance. This boost can be removed by closing the duct. The dynamic mike has several advan- tageous features. If it is well designed and carefully constructed, it can provide a very wide and smooth frequency response. In addition, it is quite sturdy and can take its share of hard knocks without damage. Fig. 2. Basic de- One of the most important characteris- sign of a bimorphic tics of a dynamic microphone is its low out- crystal microphone put impedance. This is a valuable feature is shown below. since it allows long cables to be run from At right is the Sonotone CM -l0 the mike to the amplifier without excessive ceramic micro- hum pickup. But this low output impedance phone. necessitates the use of a special step-up transformer at the amplifier to match it to a high -impedance input. The polar pattern of a dynamic mike is normally omni-directional-that is, it picks up sound from any direction equally well. It is possible, however, to modify this pickup pattern, as we shall see. Crystal and Ceramic Mikes. Some OUTPUT crystalline materials such as Rochelle salts barium produce volt- CRYSTAL and titanate electric ages when they are bent. This phenom- DIAPHRAGM enon is the basis for the operation of both the crystal microphone and the crystal phono pickup. SUSPENSION CASE There are two types of crystal mikes: the 56 POPULAR ELECTRONICS

AmericanRadioHistory.Com STEP-UP granules are attached to a diaphragm so TRANSFORMER that the carbon is compressed "in tune" DIAPHRAGM with the variations of the sound waves as the diaphragm moves. The resistance of CARBON GRANULES the carbon varies at an audio rate as the carbon is compressed. When the carbon LOW -VOLTAGE "button" is connected to a battery, its POWER SUPPLY varying resistance causes the current going through it to vary also. These current Fig. 3. Diagram of a variations are delivered to an amplifier carbon microphone with through a transformer. (See Fig. 3.) its associated power supply and transformer. A carbon mike delivers high output voltages and consequently needs little amplification. But its frequency response is limited, and,' because of the changing con -

SUSPENSION STEP-UP TRANSFORMER

RESISTANCE 7 DIAPHRAGM a. I- STATIONARY O PLATE

HIGH -VOLTAGE POWER SUPPLY

Fig. 4. Elements of bimorphic and the sound -cell. In the bi- a capacitor mike morphic type, a crystal is connected by are shown above. At upper left are a lever to a diaphragm so that the move- internal and exter- ment of the diaphragm bends the crystal nal views of the and generates a voltage. (See Fig. 2.) In Sony C37A capaci- the sound -cell type, there is no diaphragm: tor microphone. sound waves Immediately at left hit the face of a bank of is the AltTc crystals and bend them directly. Bimorphic Lansing 21D crystal mikes are inexpensive and produce "Lipstik" mike. a response up to around 7000 cps. Sound - cell types are more expensive but they go up to 10,000 cps and beyond. Crystal mikes are omni-directional and have relatively high output at very high impedances-from 500,000 ohms to 5 meg- tact resistance of the carbon granules, it is ohms. For this reason, they can be con- quite noisy. Carbon microphones are used nected directly to the input of an amplifier in telephones and in the simpler types of without using a transformer. The char- voice communications where price is an im- acteristic high impedance of crystal mikes portant consideration; they are not suited makes them highly susceptible to hum for high-fidelity applications. pickup, however, unless a short intercon- Capacitor Mikes. The moving dia- necting cable is used. phragm of a capacitor microphone is one Ceramic mikes are very similar to crystal plate of a two -plate variable capacitor. mikes in general characteristics, price, and When a fixed high voltage is applied to the performance. They are much less suscep- two plates and a resistor is placed in series tible to heat and humidity, however. with this polarizing voltage, a movement Carbon Mikes. The oldest and cheapest of the diaphragm will cause the capacitance microphone is the carbon mike. Carbon between the plates to vary, thus varying

July, 1960 57

AmericanRadioHistory.Com CORRUGATED METAL RIBBON

STEP-UP MAGNET TRANSFORMER

Fig. 5. Construction of a ribbon microphone is detailed above. Commercially available recording. Since capacitor mikes are large- ribbon mikes include ly handcrafted, they are expensive-around Shure 330 (at right) and the Dynaco B&O 50 $400.00 apiece. (upper right). Ribbon Mikes. A less expensive type of microphone that approaches the capacitor type in overall performance is the ribbon mike. This design consists of a narrow .11 ribbon of corrugated Duralumin supported at its ends in a magnetic gap. As the ribbon vibrates in response to sound waves, it cuts the gap's magnetic field and generates a the current flow through the resistor. (See voltage. (See Fig. 5.) Because it has no Fig. 4.) diaphragm and complex suspension system, Because the current variation is very a ribbon mike's resonance can be kept be- small, however, the resistor must be quite low 20 cycles. The ribbon mike is also free large to produce a useful voltage drop. This from cavity resonances and pressure dou- results in a high -impedance circuit which bling. would be susceptible to hum and noise pick- Ribbon microphones have extremely low up if a long shielded cable leading to the output impedances and thus have built-in amplifier were used. For this reason, the transformers to match them to the line preamplifier is built right into the micro- (usually 600 ohms). Frequency response in phone; the preamp is designed to have a less expensive models can extend to beyond low output impedance so that cable length 13,000 cycles, and some broadcast and re- is not critical. cording ribbon mikes go from 20 to 20,000 In the old days, the physical size of cycles. capacitor microphones made them unsuit- The main disadvantage of the ribbon able for most purposes. Recently, however, mike is that the ribbon itself is very fragile the techniques of miniaturization have and will not stand up to rough treatment. helped the capacitor mike come back with To avoid damage to the ribbon, it should a bang. One example, the Altec Lansing not be used outdoors if there is a wind. "Lipstik" microphone, is even smaller than Also, a ribbon mike has a tendency to over- most dynamic and crystal mikes, being only accentuate the bass end when picking up a 51;" in diameter and 6" long, complete with a voice at close range. This effect has been built-in preamplifier, but less the power reduced in many models, however, by the supply which is in a separate box a few feet addition of damping pads or electrical net- away. works to roll off the low end. The new capacitor mikes approach the The ribbon mike differs from the others ideal in frequency response and dynamic we have discussed so far in that it is bi- range characteristics, covering the entire directional. A sound that comes from the audio range with an unprecedented even- side will not move the ribbon and there is ness and lack of coloration. For this reason, no voltage generated. Sounds from the they are widely used today in professional (Continued on page 107) 58 POPULAR ELECTRONICS

AmericanRadioHistory.Com . .:

L=p 1 aa

By LEO G. SANDS

COMMON complaints about marine radiotelephones are noisy recept_on, in- adequate range, and interference from other vessels. More often than not, however, the boat owner doesn't really understand how to get the most from his equipment. Actually, much can be done to improve the operation of boat radios. First, consider the fact that ' n g very low power systems are in - Ship- a volved. An AM broadcastingroadcastin station's signal, for example, comes from a transmitter as powerful as 50,000 watts. But a boat radio radiates only 2 - 5 watts. Even a tele- a phone company shore station radiates only r; n e about 100 watts. Yet there are users who expect greater range from a boat radio than from a broadcasting station'. Typical boat radios are rated at 20 to 150 Radios

Good installation and operating techniques improve the seaworthiness of any marine radiotelephone

July, 1960 59

AmericanRadioHistory.Com watts input. Since power rating is. based on power input rather than output, a "20 - ."_' watt" set doesn't actually deliver 20 watts. Its final r.f. power amplifier tube consumes 20 watts, a figure derived by multiplying its plate voltage by its plate current in amperes. Most transmitters are about 50% efficient, so a 20 -watt transmitter will deliver about 10 watts of honest -to -goodness r.f. energy to the antenna. To go one step further, the transmitting range is determined by the power radiated by the antenna, not the power that it consumes. When a 20 -watt transmitter is fed into an antenna of 20 25% efficiency, the effective radiated,ipower is on the order of 2 - 21/ watts. This is low power indeed compared to a 50,000 -watt AM broadcasting station or a TV transmitter with an effec- C a tive radiated power in excess of 100,000 watts. Antenna/Ground System. No boat radio is better than its antenna system. And a good boat antenna is rarely more than 25% efficient because it simply isn't as long as it should he. For best results, the an- hull is best. If this isn't feasible,. brass or tenna should be one-half wavelength long, copper strips about 3" - 4" wide can be which, at 2 mc., would mean an antenna fastened to the inside or outside of the hull, 230 feet in length! A quarter -wave vertical securely bonded together by copper braid antenna about 115' long would be an effi- soldered or bolted to each strip. In addition, cient radiator, but even a quarter -wave an- the engine and all large metal parts should tenna is far too long for small -craft use. be bonded to the ground system to obtain Consequently, a compromise must be as much ground area as possible. made. This compromise usually takes the Recently, special grounding devices of form of a loaded antenna consisting of two porous metal have been developed which rods joined in the middle by a loading coil. are less than a square foot or so in area. The loading coil "stretches" the rods so that These devices are sponge -like in construc- the antenna takes on some of the electrical tion, and their makers claim that water characteristics of a long-wire. While this seeping through their pores helps make is not a very'efficient scheme, it is the best them effective grounds. answer engineers have come up with to But regardless of the installation, the date. proof of the antenna "pudding" is in its Many boat owners are unaware that the performance. A radio technician can de- actual antenna is only half of an antenna termine the antenna ground system efficien- system. Without an effective ground, even cy by noting how well the transmitter loads a good antenna will function poorly. A into its antenna. And the boat owner him- metal hull is an excellent ground, but good self can check antenna ground efficiency by electrical contact must be made with it. A noting how far he can talk. bolt through the hull is one safe bet, with Modulation. Most modern transmitters the hull scraped clean so that good electri- arc designed so that modulation cannot cal contact can be made with a piece of flat exceed 100%. But if modulation is less than metal braid (1/z" or larger) connected to the 80%, range will be impaired. radio ground terminal. Both the metal braid In most transmitters, a modulation limit- and the antenna lead-in should be as short er is included to prevent overmodulation as possible. and to maintain a higher average level of To obtain a good ground on a boat with modulation. Weaker sounds picked up by a wooden or plastic hull, a large (12' x 12', if the microphone are boosted and louder possible) copper plate on the outside of the sounds are prevented from being amplified 60 POPULAR ELECTRONICS

AmericanRadioHistory.Com 411 A handsef is often better than an ordinary microphone for marine use. In- experienced users find it hard to hold a telephone -type handset improperly. Also, the handset's directicnal properties cut noise pickup from wind, rough weather and the boat's motor.

Microphones are sometimes a source of trouble for the uninformed boat -owner. Used correctly, they should be held two to three inches from +he lips in order +o deliver enough output for good modulation.

to a level that would produce overmodula- attainable. Talking more loudly than re- t ion. quired to obtain maximum modulation The percentage of modulation achieved won't increase range and can actually cause depends to some extent upon how the mi- distortion. crophone is used. Talking too softly into a Input Voltage. Transmitting range is microphone at an excessive distance usu- also determined in part by the input volt- ally results in insufficient modulation. And, age applied to the transmitter. On small because of the action of the modulation lim- craft, power is usually obtained from a iter, background noises picked up by the 12 -volt storage battery, but the actual volt- microphone may be too loud, making it dif- age across the battery terminals will vary. ficult for a distant listener to separate the What's more, there is a loss in the wires voice from the noise. leading from the battery to the equipment. By talking into the microphone at a dis- This loss is determined by the size and tance of 2 - 3 inches, in a normal voice, ade- length of the wires as well as by any elec- quate modulation and good range should be (Contiiwed on page 104) July, 1960 41

AmericanRadioHistory.Com --..'314-bdriGNAT r

.-*-- 1"12.

" o P . Build an Electronic

Inexpensive unit protects your boat, car,

NOW THAT the boating season is in full tainers or layouts can be used, if you wish, swing, you'll want to take steps to pro- since the circuit is not critical. tect your shipboard gear from burglary and Relay KI plugs into a standard octal tube vandalism. Here's an inexpensive and sim- socket and transistor QI into a transistor ple burglar alarm that can turn on a warn- socket. All other parts are supported by ing light, a horn, or even a siren, if any their leads except "five -way" binding posts unauthorized persons attempt to remove BPI, BP2, BP3, and BP4, which arc equipment from the craft. It can also be mounted at one end of the box. Be sure to used to protect ham gear in your car, or position BPI and BP2 exactly %" apart in guard your home while you're away on order to match the spacing of banana plugs vacation. This electronic watchman will PI and P2 on the test unit. If desired, make your summer holiday more carefree potentiometer Ri and transistor Q1 can be and enjoyable. mounted in a separate plastic box as shown. The alarm uses only a few parts and will The relay should be waterproofed before operate for months on its self-contained it is installed in the alarm. To do so, remove battery-standby current is only 50 micro- the four screws from the relay's plastic amperes. Due to the low operating voltage cover. Then, using lacquer or clear nail and current, there is no danger of shock. polish, coat the area between the octal base Even so, the relay in the alarm can carry and the metal flange, both inside and out- up to 2 amps at 125 volts, enough to oper- side the relay. Replace the cover and ate most bells and sirens. screws, and coat the mating area between Construction. The model was built into the relay cover and the metal flange. Use a 6" x 31/2" x 11/z" plastic box with a hinged plenty of lacquer around each of the four top, as shown in the pictorial. The accom- screws. panying test unit was built into a 27/8" x Adjustment. Before adjusting the alarm, 11/4" x 11" plastic box and is designed to be sure that the relay and transistor are plug into the burglar alarm. Other con - firmly seated in the sockets and that the 62 POPULAR ELECTRONICS

AmericanRadioHistory.Com ,.~Ark---0 ..- ~^~. .

. .. C. o y 5

° óa _.

, o 4zw Burglar Alarm

or home while you're away By ED DUDA

18 -volt battery is properly connected. alarm should now be ready for installation. Wrong battery polarity can ruin the tran- Be sure to keep a jumper wire across sistor. BP3 and BPy when the unit is not con- Next, plug Pi and P2 of the test unit nected to an alarm circuit. This keeps cur- into binding posts BP1 and BP2 of the rent drain on battery B1 at a minimum. burglar alarm; lamp PL1 on the test unit Installation. One of the most important should light. Connect binding posts BP3 considerations in any burglar -alarm system and BP.4 with a length of wire and adjust is to prevent the burglar from disabling potentiometer R1 until the lamp goes out. the alarm. Once a convenient hiding place When you remove the jumper wire, the has been selected for the alarm, the next lamp should light once more. The burglar step is to hook up binding posts BP3 and

Simple test unit (at right) clecks ouf the alarm. Binding posts are hooked up to the warning and sensing circuits. fltv 11 1144 i

July, 1960 63

AmericanRadioHistory.Com PARTS LIST la 91 -18 -volt battery (two Burgess 2N6 9 -volt bat- OT usco teries or equivalent in series) BPI B2 -1.5 -volt penlight cell (test unit) BP2O BPI, BP2, BP3, BP4-Five-way binding post (La - s layette MS -566 or equivalent) KI-S.p.d.t. relay, 4000 -ohm coil; 2 -amp., 125.volt - contacts; 1.9 -ma. operating current (Kurman 23DB42 or equivalent) 81 18V. PIN NUMBERS ON PI, P2-Banana plug OCTUL SOCKET PIA-LS-volt flashlight lamp (test unit) Q1-2N188A transistor R1 -250,000 -ohm, 2 -watt potentiometer fOhmite Single (Q I) CLU-2541 or equivalent) transistor 1-Octal tube socket energizes relay KI when PI 1-Transistor. socket circuit across BP3 and Misc.-Hardware, plastic boxes, battery clips,. BP4 is opened. Test BI penlight cell holder, penlight bulb socket, etc. unit plugs into BPI and pPH, -i BP2; ramp PLI lights when KI is energized. TEST UNIT

BP4 to a "sensing" circuit at the property requiring protection. The sensing circuit is nothing more than a switch that is inad- vertently operated by the burglar when he equipment or open a METAL attempts to remove CONTACTS window or door. Typical sensing circuits, one for each of these three cases, are shown at left. The final step is to connect binding posts BP1 and BP2 to the warning circuit, which TO BP3, BP4 can be any of a number of electrical signal- ing devices. Two typical warning circuits are shown at right. On your car or boat, you can use your horn for an alarm. v --METALLIC RIBBON To do this, connect one lead from binding WINDOW OR ALUMINUM FOIL post BPI to one horn -button terminal and another lead from BP2 to the other horn - button terminal. In other installations, BP1 MOVABLE CONTACTS and BP2 can he connected to an alarm ON WINDOW to a door METAL BAR ON SILL gong, flashing light, siren or even bell. If the equipment to he protected is a piece of mobile electronic gear housed in a TO BP3, BP4 metal cabinet, attach leads from BP3 and BP4 to separate metal plates underneath FIXED CONTACT the cabinet. Should the cabinet be lifted I ON DOOR JAMB MOVABLE off the metal plates, the circuit through CONTACT ON DOOR the cabinet will be broken and the alarm set off. This same technique can be used with the front or rear door of your home. A movable switch contact should be mounted on the door and a fixed contact on the door jamb; one contact is connected to BP3 and the other to BP4. If anyone opens the door, Sensing cireu-ts are "switch- the alarm Na ill go off. Be sure to use a es' which trip alarm when they -are opened. As current is only sensing switch that will remain open once 50 microamps, alarm is safe to the door has been opened; otherwise the operate near children or pets. thief could close the door after him and thus silence the alarm. 3p-

64 POPULAR ELECTRONICS

AmericanRadioHistory.Com Layout is not critical. The author mounted potentiometer RI and transistor QI in a small plastic box inside main box. Relay K I plugs into octal tube socket. -

HIDDEN ON -OFF SWITCH CAR OR ne-c/r BOAT HORN O1-_ STORAGE tq BATTERY illy

LAMP LIGHT FLASHER BULB HOW IT WORKS The burglar alarm employs s single transistor (Ql), with a relay (KI).as as collector load. In operation. BP3 and are o- 117 V.A.C. BP4 connected to each other at the m ON-OFFHIDDEN O ALARM SWITCH equipment under protection. Potentiometer Rl acts GONG 117 V.A.C. as a voltage divider in series with battery BI and relay Kl. The arm of RI is set to a point where the base of Ql is only slightly le;s positive than Q1's emitter. Warning circuit on boat or car car use horn to This setting of R1 keeps Ql in the non-conductive sound the alarm. Installations in homes or stores state; insufficient current flows to energize relay Kl. can operate a 117 -volt a.c. system. Open hidden When the circuit actor: BP3 aad BP4 is opened, the switch to silence alarm after it has been tripped. base of Ql goes very negative and QI conducts heav- ily, energizing Kl. With KI energized, normally open contacts I and 6 of L'l close and connect binding posts BPI and BP2. This switches on the warning device and thus sounds an alum. When plugs PI and P2 of the test unit are plugged into BPI and BP2, battery B2 will light warning lamp FLI if there is a break in the circuit connecting BP3 and BP4. In actual use, a bell, siren, or other warning device is substituted fcr the test unit.

July, I96Q 65

AmericanRadioHistory.Com The Strange Inhabitants of -í r'

75 -Meter phone

Then there's the fellow who just won't There's no lack of unusual characters sign off. He's more difficult to disengage on 75 -meter phone. How many than a Novice after his first DX contact. of the operators described here This verbose chap comes back for a "final final," have you come across? final," then for a "short final final and so it goes. After a half hour or so of this kind of thing, you begin to flush with By the excitement of the challenge. As time JAMES F. VAN DETTA, WA2FQZ slips by, an earnest duel evolves. If you're fortunate, QRM renders the official decision a draw. ONE of the most popular meeting places Perhaps you've run into the guy who for hams is the 75 -meter phone band. leaves you to "tie the ribbons on it" while Although the propagation characteristics he sneaks off the frequency to find another of this band aren't particularly conducive QSO. He doesn't even wait to hear your to exotic DX, evening time finds the fre- final transmission before scampering off in quencies between 3800 and 4000 kc. buzzing search of another contact. After you sign with activity. off with him and tune up about 30 kc., there Most of the operators that work this band turn up night after night to talk about anything and everything under the sun. The great majority of them are fine, considerate gentlemen; a few are miserable clods. In between are all kinds imaginable. Here are some of the stranger types you'll meet on 75 -meter phone. FIRST, let's consider the lovable character who calls CQ, gets you to answer his call, transmits for half an hour, and then signs off because he has to run some urgent errand. As he signs off, lie asks you to give him your handle quickly because he "can't final." "My even hang around for your Waiting for the fellow who continually has to final!" you weep pitifully, "I haven't even search for words can be a harrowing experience. had my initial!" His best bet might be to try a written script. POPULAR ELECTRONICS 66

AmericanRadioHistory.Com he is, already in another QSO. It gives you background noise smashes into your ears. a nice warm feeling to know you have been "Well, I ROAR -ROAR hope you ROAR - talking to the frequency instead of to an- ROAR -ROAR can copy me ROAR -ROAR other human being. over there ROAR -ROAR -ROAR." This Did you ever meet the fellow who doesn't situation has to be experienced to be ap- seem to know the name of anything? He preciated. makes you want to break into his trans- "A lot can still be said in favor of a hand - mission and supply him with the appropri- operated T -R switch," you explain to the ate word. "At last my ah-uh-oh my ah-uh nice man in the white coat as he adjusts trans uit-ah mit ah -oh ter is working fine your snug -fitting jacket. now, but my uh.-ah-oh . . ." The poor guy just seems to be noun -less. HE independent fellow with his own Worse than being noun -less is the opera- 1 phonetics often confuses more than he tor who is thought-less. "Yessiree. Now informs. If his name is Pat, for example, his phonetics might be "psychological; Aetna; tsetse." If the QRM is pretty rough, you get only the last word of phonetics. So when you come back at him with, "Well, Fifi, the QRM is pretty bad here. . " it hits him where it hurts most-in his phonetics! The operator who avoids "I," "me," and "mine" like the plague is apparently unaware that "I" and its various forms are perfectly respectable. "We have enjoyed the o

Transmit -receive switching can be complex, but this guy carries things too far. If he goofs his switching sequence, your ears will be the losers.

you wanted to know about ... (long pause) ... Say, did you ever hear about that idea to have all ... (pause) ... I wonder if my SWR will ... (long pause) ... When I tell you . . ." This fellow seems determined never to finish a thought. we Racks of home-brew equipment fill the h-m shack Since all can't afford the kind of of the self-styled "electronic designer." You'll transmit-receive switching we would like, recognize him on the air by his 60 -cycle hum. sometimes you'll find a ham who has to throw a dozen switches before he turns it QSO, OM. It has been a pleasure for us to back over to you. Once in a while, he will meet up with you." You wonder if perhaps get his switch -throwing sequence mixed up he is a pair of Siamese Twins. and his signal will howl and screech until Then there's the fanatic single-sidebander he completes his switching operations. As who scornfully refers to AM as "ancient your eardrums vibrate against your chat- modulation." Following his wobbly signal tering molars, you'll have the unforgettable as it wanders around the band requires an experience of knowing what a sound en- alert pair of hands on the receiver controls. gineer means when he talks about the As he recites his entl-usiastic praises of "threshold of pain." SSB, he also remarks that the reason you're Your nerves can also be quickly worn to a having trouble receiving him must be faulty frazzle by the fellow who has an electronic operational technique or, your part, or may- voice control circuit that isn't functioning be a design defect in your 75A4. properly. After he mutters each phrase, And who hasn't met the operator with a his carrier snaps off with a thump and the homebrew rig who fancies himself an elec- July, 1960 67

AmericanRadioHistory.Com tronic designer? This character is easy to When he finally comes back to some of recognize because his signal features a the stations that have been calling him, this healthy 60 -cycle hum. He joyfully spends guy says, "Thanks for the shout, fellows. three times the cost of a commercial kit to I was just tuning up the ole rig here. get one-third its performance and sneers Wanted to make sure it was socking out the disdainfully at anyone who buys a kit. If ole soup. You know, I've been on the air he only knew how much his performance umpteen years, and I never yet called a CQ. could be improved! Don't believe in it. No need for all this Closely allied in spirit to the "electronic CQ'ing " designer" is the self-appointed "electronic Occasionally you run into a would-be genius." You'll find him to be a generous comedian. He has a new joke every day. A fellow when you are experiencing some sample of his refreshing humor goes like trouble with your rig. With unmatched this: swiftness, he will offer a diagnosis of your "Did you hear the one about the two difficulty. halun coils? There was these two halun Your problem, he will tell you with an air coils and one says to the other, 'Social of condescension, is due to one or more of security'." Here he breaks into riotous laughter as he turns it over to you. "I don't get it," you admit. He comes hack howling with hilarity, "You won't-ha ha ha-until you're 65!"

RAFFIC NETS are a distinct plus for 1 ham radio. You always feel your shoul- ders go back a little in pride as you hear the net begin to pass messages. "Being discharged on April 5th. Bake a cake, Mom. Warm up the car, The amateur comedian really breaks himself up with Dad. See you both soon. Love." His attempts at humor are his own corn -ball jokes. who is usually met with cold silence at the other end. So goes a message from a soldier shortly to join his parents. You slowly break into a smile of vicarious satisfaction. the following: (1) bad tubes, (2) bad com- Then it hits you. This is the 28th of April! ponents, (3) shorts, (4) improper trans- The message is over three weeks old! The mitter tuning, (5) faulty design, (6) faulty poor ex -GI will probably receive his own wiring, (7) something wrong with antenna message at home. Or maybe it will be re- system, (8) something wrong with a.c. line. ceived by one of his descendants. And wonder of wonders, when you do For a first-hand course in the torments find your trouble, it is almost invariably one of frustration, try a QSO with the joker or more of the causes suggested by the who has a one-track mind. Regardless of helpful diagnostician! Are there any others? your comments or questions, he will ignore How quickly this wizard can pinpoint trou- your transmissions. If he's a hi-fi buff, for bles is an endless source of amazement. example, he will come back to you with, "Yeah, OK there, OM. Well, today I got ACHARACTER we could do without is this new speaker system for the hi-fi. Com- the fellow who tunes up his transmitter plete absence of coloration with acoustical without checking to see if the frequency suspension, you know? Say, when you com- is clear. Listening to his variable -pitched pare it with the old system I had . . ." and whistling, one becomes quite convinced that on he rambles. he must be a cross between a parrot and an Finally, to complete our cast of charac- intoxicated canary. However, he dispels ters on 75 -meter phone, there is, as you may this assumption to some ex ent by his have suspected, the unlikely individual who "count -ups" and "count -downs." He usually makes notes on some of the other in- counts up to about 100 and then back down habitants of 75 -meter phone and sends in an to POPULAR ELECTRONICS describing to 1 . . . by l's, as if he were training to article become count -down officer at Cape Ca- them. His only additional words are, naveral. "BCNU on 75!" 30

68 POPULAR ELECTRONICS

AmericanRadioHistory.Com By CHARLES CARINGELLA, W6VJV

iAD1M~ LAMP

LAMPS have been made using everything from abalone shells to zebra hides. For the electronics enthusiast, what could be gish' .At#'; ar more appropriate than a lamp made from . a large transmitting tube? Such a lamp can be built for less than ten dollars and completed in one evening. The only tools you'll need for the project are an ice pick, a drill, a screwdriver, and a soldering iron. Your best source for one of the big transmitting tubes is an electronic surplus store. Ir These tubes come in a variety of sizes and .. ., usually sell anywhere from a dollar up. Size isn't critical, but the one you choose must have a plate cap. The Western Electric 701A tube used here costs about $8 ($16 for two, if you want to make a pair of matching lamps). It's especially well suited for use in a lamp because its pins are actually hollow lengths of hi" tubing-this makes passing leads through the pins a comparatively simple matter. Then, too, one pin is High -power transmitting tube located at the top of the tube and four at the bottom, which gives the 701A the necessary top cap and base makes attractive fable lamp connections required for the lamp. To start the actual construction, make a small hole in the end of one pin to protection in the event the tube should release the vacuum. This can be done with break. any sharp instrument, such as an ice pick, Next, drill a i/s" hole in each of the since the copper pins are very soft. Play four bottom pins and a 38" hole in the it safe by wrapping the tube in several lay- top pin. Be careful when drilling-and ers of rags until it is completely covered don't attempt to drill before the vacuum except for the pins. The rags will absorb any has been released. accidental shocks and offer some degree of Two leads of insulated No. 20 hookup July, 1960 69

AmericanRadioHistory.Com First step in wiring lamp is to pass two insulated leads, one at a time, through top pin, inside tube, and out bottom pins.

Self -tapping screws inserted in unused tube pins hold tube on chassis base. Terminal strip is tie -point for leads and line cord.

Socket and switch assembly at - tacked to top pin completes lamp. 3 QSL's or circuitry applied to shade imparts electronic "touch."

wire are required to supply power to the light bulb. Each lead is fed through the

_ top pin, one at a time, and passed through the tube and out separate bottom pins. (The other two bottom pins are used to mount the tube to the base with a couple of self -tapping screws.) This is the critical. point in the wiring-all in all, it takes a little patience and about 15 minutes to work the wires through. When this is done, fasten a standard lamp socket -switch fixture to the top pin and connect the wires to it. Now prepare the base, which is a standard 5" x 7" x 2" aluminum chassis (Bud AC - 402 or equivalent). If you wish, you can use any other size chassis or mounting base that suits your decor. First drill four 14" holes through the top side of the chassis to match the location of

, the tube's bottom pins. Next, drill a gís" hole at the rear apron of the chassis to accommodate the power cord. After all the holes are drilled, apply three or four coats of quick -drying enamel to the chassis and let it dry thoroughly. Then mount the tube to the base by inserting sell -tapping screws through the appropriate holes in the chassis and into the remaining two tube pins. Install a 3/,," rubber grommet in the power cord hole and connect the cord to the leads coming from the tube. A two -lug terminal strip can be used as a tie -point; if a terminal strip is not used, twist the leads together and carefully insulate them with electrical tape. Add any lamp shade your heart desires, ` and your "transmitting tube" lamp is ready for operation. -a(11-

70 POPULAR ELECTRONICS

AmericanRadioHistory.Com hat they dog yv or and `"W .,...--, how theY ;-: `:_

r--1' 0 c '. J ..,tw'S ,.. C~ . `;

-1.1""tos..a" 1:1' .»..yTr

'k 't 11,A__ ta .,'y- t = ...- : .... . :n_...... o

. '%' ' s:-:_h,?:fi.;; -s; `-- By KEN GILMORE

THE ATOMIC SUBMARINE Triton glides swiftly and silently through the deep. As its pov er plant purrs steadily, scores of electronic watchdogs probe every part of the sub's powerful reactor. Suddenly the pressure in a reaction chamber begins to rise over the al- lowable amount. One of the electronic guar- dians instantly notes the rise and applies a corrective signal-before a human operator could know that anything had begun to go wrong. Scores of magnetic amplifiers in the The electronic watchdogs that keep the world -circling Triton control its atomic Triton's powerful nuclear plant reactor. Above, finishing touches are operating put on the General Electric "magnetic" without a hitch are magnetic amplifiers- that monitors the reactor's temperature.

July, 1960 71

AmericanRadioHistory.Com Stages in the assembly of a magnetic amplifier. Its similarity to a transformer in con- D.C. CONTROL struction technique and gen- VOLTAGE eral appearance is striking.

RECTIFIER,

transmitting stations used his circuits. By the early 20's, however, the flashy vacuum tube had taken over, and the "magnetic" was almost forgotten in this country. It was not forgotten in Germany, however, as we found out when World War II started. In the years between the wars, the Germans had brought the magnetic ampli- Fig. 1. Basic circuit for fier to a high state of development. War- half -wave magnetic amplifier. time found them using magnetics for reliable, accurate, and trouble -free control of everything from gun turrets to automatic almost a hundred of them are used for this pilot systems, and they even used them in critical job. Yet these same magnetic am- the V2 rockets. plifiers-the heart of the control system of Awakened to the possibilities inherent in one of the world's most up-to-the-minute this design, Allied scientists began to push fighting machines-are straight out of the the development of magnetic amplifiers. horse -and -buggy era. Before much progress had been made, Forgotten and Rediscovered. Mag- though, the war was over. But the spark netic amplifiers came into being when the had been kindled, and a few years later century was just one year old. It would Vickers Inc. (now a division of Sperry be six years-in 1907-before a youngster Rand) came out with the first commercially named Lee DeForest would make news produced magnetics. with his audion, the world's first vacuum - By that time, interest had been aroused tube amplifier. And the transistor was still all over the world. In the following decade, 47 years in the future. hundreds of other firms, including all the For a while, it looked as though the mag- big names in elect' ical and electronic equip- netic amplifier would hold its own against ment, have added magnetics to their prod- that upstart, the audion. In 1916, E. F. W. uct lines. And almost no branch of industry Alexanderson, the electronic pioneer, em- now operates without them. ployed magnetic amplifiers to modulate his Flux Controls Current. A modern-day early transmitters and many World War I magnetic amplifier is, essentially, nothing 72 POPULAR ELECTRONICS

AmericanRadioHistory.Com ~-~..-'

.. Wm. ,--zi:7; f

-h

-1i' I-

First, let's look at the basic half -wave cir- Magnetic amplifiers like the Vickers snit cuit shown in Fig. 1. above allow fingertip control of elaborate A d.c. current flowing through the con- lighting systems in TV studios. (NBC photo) trol winding will cause a build-up of magnetic flux in the iron core. The greater the flux, the lower will be the impedance of the output winding. With a lower impedance in the circuit, more current will flow from more than an iron core with two or more the a.c. power supply through the output coils of wire wound around it. In construc- winding and the load. tion and appearance, it is similar to a trans- When the current in the control winding former. But there the similarity ends. reaches a certain point, the core is said to A magnetic amplifier-or saturable reac- be saturated, which means that it has all tor, as it is sometimes called-is a true the flux it can hold. At this point, the im- amplifier. Like a vacuum tube, it uses a pedance of the output winding is very low, small signal to control a large one. But and the current through the load is very there are sharp differences. Where the high. On the other hand, when there is no vacuum tube controls a current flowing to control current flowing, and consequently a d.c. power supply, the magnetic amplifier no flux in the core, the output impedance controls an a.c. flow. While the vacuum is extremely high, and practically no cur- tube is primarily a voltage amplifier, the rent flows through the output winding or magnetic is a power amplifier. And where the load. Thus, by controlling the current the vacuum tube uses voltage variations to through the control winding, the output control a flow of electrons, the magnetic winding impedance, and consequently the amplifier controls current flow through a current through the load, is made con- coil by varying magnetic flux. tinuously variable. Magnetics come in half-wave and full - A rectifier in series with the output wind- wave types, as do a.c. power supplies. ing keeps the constantly reversing polarity July, 1960 73

AmericanRadioHistory.Com . .., : y' ;r--LI1wÍr-a... ° ' -

El; ` . , -+s .u1! : .

4117 ' , ';' e

Thanks to magnetic amplifiers, this paper -making machine at West Tacoma Newsprint Corporation in Tacoma, Washington, can operate at 5000 feet per second, many times faster than previously possible. Magnetics continuously adjust the speed of the take-up rollers, slowing them down as the roll of paper gets larger. Control room is at left.

N of the a.c. supply from cancelling out the control winding flux. The direction of the current flow through the secondary is arranged so that the magnetic fluxes created by the two windings reinforce each other Fig. 2. Basic circuit for a rather than cancel each other out. full -wave magnetic amplifier. A full -wave circuit is shown in Fig. 2. It works like the circuit in Fig. 1, except that it makes use of both half cycles of the a.c. supply current. The two halves of the output winding are wound so that the direction of the magnetic flux created by both of them in the center leg of the core is the same as the direction of the flux created by the control winding. The bias winding can be used to control the general range of the amplifier's operation, just as the bias on a vacuum tube causes the tube to operate on a certain part of its characteristic curve. In a magnetic amplifier, when a small bias current flows, a certain amount of flux is continuously present in the core, even with no control voltage supplied. Thus, the impedance of the output winding will never reach its maximum value, nor will the current through the load reach its minimum. Many magnetic amplifiers have an additional control winding which is used for feedback. This winding taps a certain amount of the output circuit's current and applies it back as a control current. As with a vacuum tube, the feedback can be 74 POPULAR ELECTr.ONICS

AmericanRadioHistory.Com either negative or positive. In general, the field of entertainment, too. NBC's two negative feedback improves the linearity big color television studies-one in Burbank, of the amplifier while positive feedback California, the other in Brooklyn, N. Y.- increases its gain. have magnetic amplifier lighting -control Single -stage magnetics can he built with systems. With this setup, the lighting man gains of about 200,000, far beyond the capa- has fingertip control over each of tile hun- bilities of the vacuum tube. With a gain dreds of lights throughout the studio. He on this order, a few milliwatts of power in can control them individually or in banks, the control winding-an amount that could as he desires, working from a small key- be supplied by one or two flashlight cells- board that looks something like an organ

E Steel -rolling mills use mag- "Itt.sa..,.. netic amplifiers, too. Because ._ the steel gets longer as it is rolled, each set of rollers must i 1. turn at a slightly different z.' speed. Magnetics , keep all the rollers operating at the proper speed relationship regardless of how fast the steel is fed ,, ''' in. (Pittsburgh Steel photo) MLA

° ,I .

may control a load of 25,000 watts in the console. Unlike older types of theatre light- output circuit. ing devices-autotransformers and rheo- Rugged and Reliable. Magnetics are stats-magnetics present no fire hazard. extremely rugged. They can be-and fre- Since magnetic amplifiers have no mov- quently are-completely potted and sealed ing parts and no delicate components, they in airtight containers. They thrive on ex- last for years with virtually no mainte- tremes of heat, dust, moisture, vibration, nance. For this reason, they are used in and other adverse conditions that would put such critical applications as the control of vacuum tubes and transistors out of opera- the atomic pile in nuclear subs and in tion. Their efficiency is high, as with trans- missile -guidance systems, where reliability formers and other magnetic devices. In under adverse conditions of vibration, heat, addition, no filament current is required. and acceleration is vitaL So little heat is generated by magnetics Reliability is also the reason magnetics that they can be packed into extremely were chosen to monitor and control the small containers which need practically no critical voltages and currents of the trans- ventilation or cooling. atlantic cable. If a voltage begins to Because magnetics can handle large change, a magnetic compensates for the amounts of current easily, they are a natu- change, ar.d, at the same time, sounds an ral choice for electric furnace control. A alarm so an operator can check to find the Reynolds Aluminum Company furnace in reason for the change. If the current drawn Corpus Christi, Texas, uses such a control by the underwater repeater amplifier tubes system. Precise furnace control by mag- begins to rise, once again the alarm is given, netics also helps to "grow" transistors in and corrective action is taken automati- the latest types of transistor -manufactur- cally. By insuring that the current does not ing processes. rise to dangerous levels, the magnetics pro - Magnetics have recently begun to invade (Continued on page 109)

July, 1960 75

AmericanRadioHistory.Com On the ,Citizens Band

By TOM KNEITEL, 2W1965

ANYONE who has spent five minutes obvious table manners that CB'ers should listening on the 11 -meter Citizens Band observe. If you have any to add, send a will agree that some "rules of the road" are post card to this column with your sug- badly needed to guide operators along the gestions (keep them brief). We'll incor- path to proper, courteous, and efficient op- porate them into our code if they are ap- eration. The POPUL \R ELECTRONICS CB Cour- plicable. tesy Code" (below) sets forth some basic A CB Log Book is being issued by "FI" operating policies for CB'ers. Enterprises, P.O. Box 867, Brooklyn 1, N. Y. Even though the FCC doesn't require logs 1 Do not transmit on a channel without for CB stations, you might find it useful to first listening to see if it is clear. If keep a record of communications from your the channel is in use, stand by until it station. If you are a businessman, you will is clear. probably find that keeping track of orders and dispatches is a must. The book sells for Keep calls down to a minimum $1.98 ($1.50 to members of the Five 2 ("2W4887, 2W4887, this is 2W4580" -Watt should be sufficient). If the called Wizards National CB Club). station doesn't reply, try again in 30 We finally found out what a Hush - seconds. If there is still no answer, Puppy is. It's an automatic squelch adapt- wait 10 minutes before you call again. er designed for the Heath CB-1 (although it will work on many other CB and non -CB Say "over" at the end of each trans- receivers, too). Taking only about four 3 mission so the operator you are con- minutes to attach, it really silences the tacting will know that you expect him to transmit. receiver until an incoming signal activates it. Write to Western Massachusetts Elec- If you hear a station being called tronics, Great Barrington, Mass., about this which you know has cleared the chan- adapter if you're interested. nel, inform the calling station. A pocket-size field -strength meter is now available from Quaker Electronic Co. of Always help in an emergency, even if Plymouth, Pa., for $7.95. Weighing only 5 the extent of your help is to cease 11/2 pounds, it shows the maximum power transmissions and keep the channel radiated by your This open. transmitter. unit comes in two models-all-band or for your

a station accidentally interferes specified frequency. eIfwith your communica+ions, request Canadians who want to have a Citizens that the station stand by for a few Band should get in touch with Larry D. moments until your communications Whiting of Strathroy, Ontario. Larry is are completed. You should then fin- spearheading the cause and has already re- ish your contact as soon as possible. ceived a huge response to his letter on Ca- nadian CB which appeared in our March Never work cross -channel unless it is issue. 7 the only way to send an extremely important message. If you must work Larry was informed recently that the cross -channel, ask the other station to Department of Transport is conducting a give your channel a quick check to survey into the practicability of Canadian see if it is clear. CB. That's a start, and we wish Larry and his group the best of luck. CB would cer- Does your station abide by the POP'- tainly be a boon to the many people living tronics "CB Courtesy Code?" It should. But in Canada's wide-open spaces where land - these pointers are only a few of the more line communications don't exist. 30 76 POPULAR ELECTRONICS

AmericanRadioHistory.Com how to eixtend the life of your records

IV fittemu

Here's what you should know

about record wear and care

By JOHN MILDER

WHEN the time comes to show off your hi-fi rig, you frequently find that your favorite records just don't have the sparkle they once had. Annoying pops and clicks, distortion, and muffled highs supply the all -too -audible evidence of record wear. To make your system sound its best, you reach not with your finger, either. A camel's hair for that brand-new record fresh from your brush is just about ideal; it will clean off dealer's stock. the dust and dirt, but it won't damage the There's no denying that record wear will stylus' delicate suspension system. take the fine edge off your listening enjoy- There's no way to predict just how long ment unless you take active measures to your particular stylus will last. It depends prevent it. Fortunately, there are many on how much listening you do, the kind of ways to save your records from unnecessary record player you use, and the amount of punishment. With a little help from you, pressure on the stylus. In any event, don't they can continue to sound brand-new even wait until your records begin to sound fuzzy when they should be eligible for an old -age before you have your stylus checked. By pension. Let's look at the inside story on the time you can hear the effects of a worn record wear and see how it can he pre- stylus, it has already been at work dam- vented. aging your records. Stylus Condition. Since the tip of your If you don't use a diamond tip, you should stylus is in constant contact with your rec- have your stylus checked at least once a ords, it has a crucial influence on record month. A diamond should last a year or wear. The first rule is: keep it clean-and more, but if your record playing is a daily July, 1960 77

AmericanRadioHistory.Com v

Camel's hair brushes are ideal for keeping the tip of a stylus clean. Don't use your fingers-you may damage the pickup.

habit, it's a good idea to start checking at the six-month mark and every month or so thereafter. When it's time for stylus replacement, buy a completely new assembly. A few companies will still re -tip your old stylus bar, but the small saving involved isn't worth the disadvantage of keeping a stylus assembly which has probably lost most of its original compliance. A replacement made or approved by the manufacturer of your cartridge is the best way to make sure that your records get the treatment they de- Tracking pressure is serve. easily checked with Cartridge Compliance. Probably the the assistance of a good pressure gauge. next most important factor in record wear is the design of the cartridge itself. The battle between a poorly designed cartridge and your record grooves will always result in your records coming out on the losing "pinch effect"-which requires that the end. A good cartridge, though, can bring stylus move up slightly when highly modu- your records safely past the hundred -play lated sections of the groove reduce the ef- mark. fective groove diameter. A mono cartridge The key to your cartridge's behavior is with poor vertical compliance will plow its compliance-the freedom of its stylus straight ahead through the modulation in- to move from side to side and up and down stead of moving upward. Damage to the when following the twisting trail of a rec- grooves is the result. In the case of stereo ord groove. Cartridges vary in their com- records, poor vertical compliance will in pliances mainly because of differences in time demolish the separation between the their mechanical innards. The more work channels. the generating element inside the cartridge You can get a good clue to a cartridge's has to perform, the stiffer and less com- compliance by using test equipment no pliant the stylus assembly will be. more elaborate than your own ears. A mon- For stereo records, the cartridge's vertical ophonic record is your best listening source, compliance is particularly important. But since stereo tends to divide your attention. mono records, too-despite the fact that On a mono record, a pickup with good their grooves are modulated laterally- lateral compliance will produce a smooth demand a cartridge that has good vertical and wide frequency response, with a solid compliance. If the stylus has trouble mov- and well-defined bass. At normal listening ing vertically, it won't be able to cope with volume, the loudest recorded passages (ex - 78 POPULAR ELECTRONICS

AmericanRadioHistory.Com Loose dust can be cleaned off records by wiping them with a damp cloth. Don't use a dry cloth, however, because it will ,,%, create static electricity, causing more dust to be attracted. sl

"Billow" the record jacket when sliding a record in or ouf of it to prevent the record surfaces From rubbing against it.

Dirt that has found its way deep into the record grooves can / water. , be removed by gently washing the records in lukewarm J ..

of mono records that have been damaged by less considerate cartridges. Record -Handling Tips. Although your cartridge and its stylus have first say in the treatment of your records, you yourself are next in line. Your record -playing habits can extend-or cut short-the life of your records. Here's how to make sure that they will stay new for a long time. Stylus pressure is of primary importance cept at the innermost record grooves) and should be checked from time to time. should come through with no sense of strain The important thing here is to follow the and with no extraneous noise superimposed. recommendations of the cartridge manu- Also, with the volume control of your am- facturer. Don't make the tracking pressure plifier all the way down, you shouldn't be either heavier or lighter than the manufac- able to hear much, if any, sound coming turer suggests. While it's easy to visualize from the cartridge itself when you stand record wear caused by too much stylus more than two or three feet away from pressure, too little pressure can do just as your record player. much damage; it prevents good contact be- If your cartridge seems to flunk these tween the stylus and the record groove, tests, have it checked to see if its stylus causing the stylus to rattle around in the assembly has reached the end of the road. groove. This adds a fuzzy quality to the If the stylus seems to be in good condition sound and encourages groove -skipping. Un- but it still won't fill the bill, you should less your cartridge and tone arm are spe- think about stepping up to a better car- cifically designed for ultra -low tracking tridge. Even if you don't have a super-duper pressures, don't try to get down into the system \\ ith all-out frequency response, one- or two -gram region. both your system and your records will If you use a record changer, don't pile benefit from a better cartridge. A pickup too many records on it at once. A thick with really good compliance will surprise stack of records makes it tough for most you by "finding" music down in the grooves (Continued on page 110) 79 July, 1960

AmericanRadioHistory.Com Test Instruments

the ar 001W :.xan a . R p I weep' Generator ':Y 4 .

. c. 9 IBy G. H. HARRISON

How it works and how it is used

UNTIL RECENTLY, it was a rare serv- 1.0 ice shop or experimenter's bench that boasted a sweep generator. But the coming .8 of FM and TV has made this valuable test instrument an absolute necessity for the .6 serviceman. At the same time, the ham o and electronic experimenter have learned J that the sweep generator can be a versatile ó .4 tool in servicing and aligning a wide variety of electronic equipment. Basically, a sweep generator is nothing .2 more than a frequency -modulated signal generator. In other words, instead of producing a steady signal at one frequency, it 980 990 1000 1010 1020 sweeps rapidly back and forth over a FREQUENCY, KILOCYCLES selected band of frequencies, just like an Fig. 1. A standard signal generator can be FM broadcast station. Its output frequency used fo plot the bandwidth of an AM receiver, might start at 50 mc., for example, rise but the procedure is time-consuming. A sweep swiftly to 55 mc., dip back to 45, go up generator shows ill's complete curve instantly. again to 55, and so on. The generator would repeat this frequency sweep from 45 to 55 ages, currents, and other variables, and mc. and back 60 times each second. Such a then figuring out what is happening. would unit have a sweep rate of 60 cycles, General Applications. To get a better a sweep width or bandwidth of 10 mc. (55 idea of how a sweep generator works, let's 45 = - 10), a center frequency of 50 mc. examine the way it can be used in checking What is the purpose of a sweep genera- the bandwidth of an AM receiver. This job tor? Simply this-with a sweep generator could be done with a regular AM signal and oscilloscope, you can actually see an generator and voltmeter by taking a series overall response curve of an electronic cir- of output measurements at different fre- cuit, rather than simply measuring volt - quencies. With the receiver tuned to 1000 80 POPULAR ELECTRONICS

AmericanRadioHistory.Com kc., for example, you could take output readings while tuning the signal generator to frequencies from 980 to 1020 kc. in 5-kc. steps and plotting the output curve on graph paper. The result would probably look something like Fig. 1. But a sweep generator can be set to sweep through the same band of frequencies. Then, with an oscilloscope hooked to the receiver's output, the frequency response curve will appear instantaneously on the scope tube. While such a procedure is merely helpful when checking AM radios, it is essential for TV and FM. Thisis because the wide bandpass characteristics of TV and FM circuits necessitate the use of a sweep generator. Figure 2 shows two typical curves. For the associated circuits involved to operate properly, the shape as well as the am- Fig. 2. Sweep generators are essential for the proper FM plitude of these curves must be accurate. alignment of and TV cir- only cuits, since the curve shape is important. The practical way to align such cir- Pips are injected to aid in alignment.

SWEEP TUNABLE CATHODE - OUTPUT CONTROL - SWEEP FOLLOWER ATTENUATOR OSCILLATOR BUFFER

EXTERNAL o MARKER

BLANKING VOLTAGE VARIABLE CRYSTAL CIRCUIT REGULATOR MARKER MARKER OSCILLATOR OSCILLATOR

HEATER AND PLATE VOLTAGES POWER PHASING PHASING OUTPUT SUPPLY CONTROL o (TO OSCILLOSCOPE)

cuits is to actually see the waveforms on Fig. 3. Heart of a typical sweep gen- an oscilloscope and note how the shapes erator is the tunable sweep oscillator. It change as the alignment controls are varies its output frequency continuously and forth around a adjusted. back center frequency. Sweep "Oscillators." The block diagram of a typical sweep generator is shown in Fig. 3. Note that a "tunable sweep os- running, the frequency of the generator's cillator" has replaced the simple r.f. oscilla- output signal would continuously sweep tor found in the AM signal generator. Actu- through a band of frequencies. ally, however, there isn't a great difference Early sweep generators were made in ex- between the two. If you were to take an actly this way. A small, specially designed ordinary AM signal generator and turn the motor -driven capacitor (Fig. 4) was con- tuning knob back and forth, the output fre- nected across the main oscillator's resonant quency would vary continuously as you tank circuit. Today's sweep generator ac- turned the knob-you would be sweeping complishes the same thing but generally the generator through a band of frequen- uses more modern sweep circuits. cies. A small motor attached to the knob There are several all -electronic sweep could be used to drive the tuning knob back methods in current use. The Heath TS -4A and forth automatically. With the motor sweep generator, for example, employs the

July, 1960 81

AmericanRadioHistory.Com "Increductor," a transformer -like device capacitance appearing across the tank cir- in which the inductance of one coil is con- cuit also varies, and so does the oscillator trolled by the amount of current flowing frequency. in the other. Figure 5 shows a simplified Tunable Swept Oscillators. There are diagram of the Heath circuit. two common methods of controlling the The a.c. current flowing through the pri- output frequency of the sweep generator. mary winding of the Increductor creates a Some units have a tunable swept oscillator magnetic field in the common core. The -that is, the frequency -modulated oscilla- higher the current, the less the permeabili- tor can be tuned through the entire range ty of the core, and, consequently, the lower of the instrument with the main tuning the inductance of the secondary coil (which control. This circuit has the important advantage of simplicity, e+ v,.-_ but it has one drawback, too. There is some variation in the sweep width as the center frequency is changed. To over- come this, some generators operate on a MOTOR -DRIVEN SWEEP somewhat different principle, using the CAPACITOR basic circuit shown in Fig. 7. The swept oscillator operates at a constant 100 mc.; the

e+ INCREDUCTOR

Fig. 4. Motors once turned capacitors to provide sweep, but most sweep generators today have electronic sweep circuits.

Fig. 5. Heath TS -4A sweep generator uses an Increductor to provide electronic sweep from Colpitts oscillator circuit.

forms part of the oscillator tank circuit) . tunable oscillator has two bands -100-200 Thus, the oscillator frequency sweeps back mc. and 200-300 mc. The outputs of the two and forth with the 60 -cycle current applied oscillators are heterodyned to give any sum to the primary of the Increductor; the or difference frequency between 0 and 400 greater the current, the wider the frequen- mc. (In practice, the output would probably cy swing. be used only up to 300 mc., as shown in the The small rectifier in the Increductor diagram.) Since the frequency of the swept primary circuit keeps just enough d.c. cur- oscillator is fixed, the sweep width is abso- rent flowing so that the tank inductance is lutely constant over the entire range of the maintained about halfway between its instrument. maximum and minimum values with no Other Controls. Most sweep generators a.c. current applied. When the sweep cir- also contain one or more marker oscillators cuit is turned on, the oscillator's frequency (see Fig. 3). These oscillators generate swings about equally above and below the small markers or "pips" which can be seen center frequency, rather than in just one on the output waveform (see Fig. 2). direction as would be the case if the recti- Since the frequency of the marker pip is fier weren't used. known from the marker dial setting, an op- Another popular method of sweep modu- erator can adjust the waveform until the lation is the reactance tube, shown in Fig. pips appear on exactly the proper part of 6. Briefly, the oscillator "sees" the react- the curve. He then knows that the wave- ance -tube circuit connected across its tank form is accurately aligned. Many genera- circuit as a capacitor. As the reactance - tors have two marker oscillators: one tube control voltage varies, the circuit crystal -controlled, the other tunable. The 82 POPULAR ELECTRONICS

AmericanRadioHistory.Com B+ I

OSCILLATOR JW TANK SWEPT 0 CIRCUIT OSCILLATOR r- r F=100 MC. u>00 CENTER FREQUENCY 0-I00MC. RANGE DIFFERENCE BETWEEN F AND VFO BAND A Fig. 6. Reactance tube varies 100-200MC. RANGE DIFFERENCE oscillator frequency electrical- MIXER IT BETWEEN ly by altering capacitance in F AND VFO the oscillator tank circuit. BAND B L2.00-300MC. RANGE SUM OF F ANN VFO BAND A VARIABLE Fig. 7. A fixed center fre- FREQUENCY quency for the swept oscilla- OSCILLATOR tor increases stability; oscilla- A=100-200 MC. tor outputs are heterodyned. 8=200-300MC. crystal oscillator is used both to produce with the oscilloscope's trace. As the genera- a fixed -frequency pip and to calibrate all tor sweeps from 45 to 55 mc., for example, of the other ranges of the instrument. the scope trace will travel from left to right Sweep generators also usually have an across the face of the scope in exact syn-

input which will accommodate an external chronism. if the phasing control is properly . marker oscillator. An ordinary signal gen- adjusted. erator can be used as an external marker. Aligning Receivers. The actual proce- With this arrangement, it is possible for an dure for aligning a television receiver is operator to have three separate, individual- quite complex, and varies considerably ly controllable pips on the sweep-two from from one set to another depending on the the generator's own oscillators, and one circuits used by the manufacturer. There- from an external oscillator. (A skillful op- fore, even experienced servicemen usually erator can have e\ en more pips by mixing find it necessary to have the manufactur- the outputs of the various oscillators to er's alignment instructions on hand before produce a series of harmonics at proper undertaking this job. Although the align- frequencies.) Simpler generators may not ment of an FM receiver is considerably have an internal tunable marker oscillator simpler, it helps to have the manufacturer's at all; instead, they may merely incorporate instructions here, too. an input jack for an external marker. Television and FM circuits operate at Sweep generators usually provide a higher frequencies than AM circuits and blanking circuit. This circuit makes the are therefore much more critical. Conse- output waveform appearing on the oscillo- quently, these 10 general rules will help you scope face easier to read by blanking out get best results when using a sweep genera- the generator's return sweep. For example, tor with these receivers: if the generator were set to sweep from 45 1. Follow the manufacturer's instructions to 55 mc. and back again, the blanking cir- exactly. Use only recommended tools, and cuit would let the rising sweep from 45 to set the controls exactly as indicated. 55 mc. go through but would "blank out" 2. Grounding is important. Connect the the return sweep from 55 back down to sweep generator ground lead as close to the 45 mc. Although TV or FM receivers can hot input as possible. If grasping the leads be aligned without this feature, the scope causes any change in waveform, try to get face in most cases is a little easier to read better grounding. Use heavy straps (hook- and interpret with the sweep showing in up wire is usually not suitable) to connect one direction only. the chassis of the various pieces of equip- There is one more control on most sweep ment together. A metal -surfaced wo'-k generators-the phasing control which is bench is ideal for this purpose. used to synchronize the generator's sweep (Continued on page 113) July, 1960 83

AmericanRadioHistory.Com `ransisfor 'Topics

the pulse to reach the reflecting surface. If the velocity of ultrasonic energy in water is assumed constant, then the lapsed e1, time is directly proportional to the distance to the bottom (or to the submerged object). The signal's velocity in water is approximately 4800 feet per second. Reducing this By LOU GARNER to unit length, it requires .000208 second for the signal to travel one foot. Suppose, now, that we send out a pulse and receive an echo exactly .0208 second later. Since this BOATING, with its allied sports of fishing, represents twice the time required for the water skiing, and skin diving, is among signal to reach the target (half going to the nation's fastest -growing hobbies. And target, half returning as echo), we divide in paralleling this increasing interest in boat- half, giving .0104 second. Dividing .000208 ing is a strong demand for economical, re- into .0104, we find that the target, be it liable, and easy -to -use marine electronic the bottom or a submerged object, is ex- equipment. As we might expect, the tran- actly 50 feet away from our signal source. sistor's chief attributes-high efficiency, The heart of the DS -1A is a governor - light weight, small size, low power require- controlled, battery -powered motor driving a ments, and good reliability-make it ideal rotor which carries a small magnet and a for use in most types of marine electronic neon indicator lamp (see Fig. 2). The motor gear. speed is held accurately at 1440 rpm, so One of the most interesting electronic that the time required for a single revolu- devices available to boating enthusiasts is tion (.0416 second) exactly equals the time the echo -type depth sounder. Heath's Model required for a pulse to travel 100 feet DS -1A, available as a comparatively low- cost, easy -to -assemble kit, is typical of commercial depth sounders. Its basic principle of operation is illustrated in Fig. 1; the " BOAT D o block diagram (Fig. 2) shows the important circuit functions. TRANSDUCER In operation, the DS -1A projects a "beam" of sharp, accurately spaced, high -frequency (185-ke.) ultrasonic pulses through the TRANSMITTED water from a barium titanate ceramic SIGNAL transducer mounted on the boat's hull. These pulse -like signals are reflected or "bounced back" from the bottom as well as -- = _ :.- REFLECTED from submerged objects, fish, or other ob- "ECHO" stacles beneath the boat-in much the same way that an echo is reflected from the side of a building or from a distant canyon wall. Water depths are measured by determin- BOTTOM ing the time required for a single pulse to be bounced back to the boat. This time F.g.1. Depth sounders determine the distance to underwater objects by sending out a pulse and then lapse is equal to twice the time required for measuring how long it takes for the echo to return. 84 POPULAR ELECTRONICS

AmericanRadioHistory.Com through water and to return as an echo. cause an echo, multiple flashes may occur. As the rotor spins, the magnet is aligned These flashes vary somewhat in intensity, once in every revolution with a small pick- depending on the strength of the reflected up coil. Passing the coil, the magnet gen- signal and hence, to some extent, on the erates a sharp electrical pulse. This pulse, size of the object. With experience, the in turn, triggers a 185-kc. transistorized depth sounder operator can tell the nature oscillator, turning it "on" for a few cycles of submerged objects (fish, sunken wreck, of operation. The high -frequency energy or what have you I and the type of bottom developed is fed simultaneously to the cer- over s% hich the boat is traveling. amic transducer and to a five -stage transis- Readers' Circuits. Robert Palladino, torized amplifier. 34 Aspen Rd., West Orange, N. J., sent in The electrical energy coupled to the the simple receiver circuit shown in Fig. 3,

MOTOR

MAGNET

NEON INDICATOR

1ST 2R0. DRIVER OUTPUT PULSED 3RD 'DIODE AMPILIF IER AMPLIFIER OSCILLATOR _AMPLIFIER . AMPLIFIER t-; AMPLIFIER CLIPPER ---i (2N383) (2N383) (R270) (R270) (R270) (R265) ,

BATTERY POWER PACK jap TRANSDUCER 9 VOLTS

Fig. 2. Heath's DS -IA depth sounder is an all -transistorized device for small boat owners. The R270 and R265 transistors are produced by Texas Instruments. transducer is converted into sound energy and projected as an ultrasonic pulse through the water. The reflected pulse or 'echo," returning when the oscillator is inactive. is detected by the transducer and coupled to the five -stage amplifier. Of course, the reflected pulse is much weaker than the original signal, due to loss of energy and dispersion in the water. Both the original pulse and the echo sig- and the audio level meter circuit in Fig. 4 nal are amplified and clipped to similar comes from Robert Bari. 207 N. Washington levels. The two signals are then used to Ave., Bergenfield, N. J. drive the neon indicator attached to the Referring first to Fig. 3, this two -transis- motor's rotor arm. Each pulse causes the tor broadcast -band receiver is a relatively neon lamp to flash. The original pulse high -gain, low-cost set requiring a mini- flashes the lamp when the magnet is lined mum of components. Coil L1 is standard up with the pickup coil; this represents Superex ferrite loopstick, C1 a 365-µµf. vari- "zero" depth. The echo pulse flashes the able capacitor. Almost any diode can be lamp at some point during its rotation, with used for Dl; types 1N34, 1N69, and CK705 the angle of rotation directly proportional are suitable. Transistor Q1 is a 2N35 to the distance to the object causing the (n-p-aa,) unit, Q2 a CK722 (p -n -p) unit; echo. Thus, the dial scale behind which the other transistors with similar characteris- neon lamp rotates can be calibrated in feet. tics could be used equally well. Since any object under the water can Aside from a pair of moderate impedance

July, 1960 85

AmericanRadioHistory.Com relative sound levels and can serve as an applause meter for amateur theatricals. This unit is also useful as a noise level meter or as a balance meter for adjusting stereo installations. A miniature PM loudspeaker (Argonne No. AR -95) serves as a microphone. Signals picked up by the speaker are coupled to a common -emitter amplifier stage though impedance -matching transformer T1 (Ar- gonne Type AR -96). Capacitor Cl is a d.c. blocking capacitor which prevents Fig. 3. Two -transistor broadcast -band Qi's base bias from passing through Ti's receiver designed by Robert Palladino. secondary winding; bias current is fur- Diode DI is the detector; audio ampli- nished through RI. fication is furnished by the transistors. The amplified audio signal supplied by QI is coupled through interstage transform- (1000- to 4000 -ohm) magnetic earphones, a er T2 (Lafayette Type TR-98) to Q2, a type s.p.s.t, on -off switch, and a battery power 2N170 n -p -n transistor in the common - pack, resistor RI is the only other electrical emitter arrangement. Base bias for Q2 is part required. The power pack, B1, can be furnished through a voltage divider made a single transistor battery (such as an RCA up of R2 and T2's secondary winding. Re- Type VS309A) or it can be made up by con- sistor R3 serves as Q2's collector load. necting six penlight or flashlight cells in From the second stage, the signal ap- series. pearing across R: is coupled through ca- In operation, r.f. signals picked up by the pacitor C2 to resistor R4. The audio signal antenna -ground system are selected by is then rectified by diode D1 which develops

Fig. 4. The +ransistorized audio level meter submitted by reader Robert Bari a d.c. voltage across output load resistor measures sound levels. Miniature speaker serves as an inexpensive microphone. R5. Capacitor C3 serves as an output filter. Operating power is furnished by 22% -volt battery B1 (Burgess Type U15), controlled tuned circuit LI-C1 and detected by diode by s.p.s.t. toggle or slide switch S1. Dl. From here, the detected audio signal As long as standard construction practice is amplified by a two -stage amplifier (Q1 - is followed, the audio level meter's layout Q2) using n -p -n and p -n -p in a complemen- and lead dress shouldn't be too critical. tary arrangement. A common -emitter cir- Care must be taken to observe electrolytic, cuit is employed, with R1 serving to limit diode, and battery polarities, of course. To Q2's base current. minimize the possibility of external hum or Bob indicates that best results are ob- noise pickup, the assembled circuit should tained with an external antenna, although he mounted in a small metal cabinet. strong local stations can be received with Sun -Powered Car. From the Interna- L1's pickup alone. tional Rectifier Corporation in sunny Cali- The transistorized audio level meter (Fig. fornia (1521 E. Grand Ave., El Segundo) 4) is designed to operate with a d.c. VTVM comes news of a sun -powered automobile. on the 0-3 or 0-15 volt scales. It measures (Continued on page 112) 86 POPULAR ELECTRONICS

AmericanRadioHistory.Com Communicating T

o u g h The Earth

IT ALL STARTED on a very hot day last You can go on the air summer. I was sprawled in a chair in my basement workshop- -the coolest spot I through the ground with this could find-and was in the middle of a beau- ultra -simple system tiful dream about the day I would get my ham ticket when the phone rang. It was Frank, and .he sounded as if he had just won the Irish sweepstakes. "Joe," he blurted, "I'm on the air in the ground." By J. C. FISCHESSER "Frank," I said, "I know it's hot, but you can live with it. Just calm down and start over." "It's the truth. I am on the air in the ground," he repeated. "Go out in your back yard and drive a ground rod at the back of your lot. Run an insulated wire from the rod into your basement, and then hook a set of headphones in series between the wire and a cold water pipe." A few questions convinced me that Frank had not flipped his lid, but he still wouldn't tell me the whole story, so I dug out an old copper ground rod and followed his instructions. When I hooked some phones between the wire from the ground rod and the cold water pipe, I heard a 60 -cycle hum, a whine or two of some higher frequency, and a few clicks and pops. This was mildly interesting, but it got old fast, and I was just about to doff the phones when I heard something July, 1960 87

AmericanRadioHistory.Com else. Code signals, bearing the unmistak- -but the other ground should have as much able stamp of Frank's shaky fist, were metal as deep into the soil as is practical. coming out of the phones! Sure enough, he Several ground rods bonded together are was on the air in the ground. better than one, and a piece or two of scrap I made it over to Frank's house-a dis- sheet metal buried along with the rods tance of four blocks-in record time. He won't do any harm. Don't make the mis- and I both have a common interest in elec- take of using the water pipes of two dif- tronics and a common struggle to master ferent houses as the two grounds. The wa- the code for our ham tests, but he always ter pipe grounds are shorted together by seems to be ahead of me when it comes to the neutral circuit of the power lines. dreaming up some new experiment. This An ohmmeter can be used to check the time he really had me guessing. quality of the ground system. Our best sys- I found him in his workshop. He had a tem measured 20 ohms between the two telegraph key, a code practice oscillator, grounds, and the poorest measured 200 and an audio amplifier sitting on the bench. ohms. In measuring the resistance, always But there was nothing new in this. I had switch the meter leads and take the aver- seen those gadgets hundreds of times. age of the two readings. The readings will "Okay, Marconi," I said. "Explain." probably differ because there will usually "Did you hear me?" he asked. be a small direct current between the two "Yeah, I heard you. How did you do it?" grounds, which will add to or buck the me- "Simplest thing in the world, Joe. I ter current, depending upon the polarity of plugged the code practice oscillator into the meter connections. There is also an a.c. the amplifier and connected the amplifier voltage between grounds which is usually to a couple of grounds; and, presto-I had large enough to show up on the low -voltage a transmitter." scale of a multimeter. "You mean to tell me I heard the Matching Impedances. Once the ground grounded output of that amplifier? How system is installed and the resistance deter- much power does that thing put out, any- mined, the amplifier must be matched to way?" that resistance. Most amplifiers have a va- "Only ten watts," Frank beamed. "I riety of output impedances, and this makes tried it out first only a couple of blocks it easy if your ground resistance falls close away, and it was so loud. I felt sure you to one of the impedances. For example, the would be able to hear it at your house." 16 -ohm output on Frank's 10-watter worked "Say," I exclaimed, "you know what this very nicely into the 20 -ohm ground at his means ?" station. "I sure do," he grinned. "It means you If you end up with some odd value that and I are going to breathe some new life your amplifier won't feed, you'll have to use into that old, dull code practice. We're go- a matching transformer between the am- ing to have our own communication circuit plifier and the grounds. This doesn't need through the earth." to be a drain on your wallet, though, since And so we did. In fact, we found two any transformer in the junk box with the more fellows in the neighborhood who proper turns ratio and power rating will wanted to learn the code, and we soon had work fine. a four -station net going. In the course of For example, one of the fellows in our setting up the net, we learned a few things net used a modulator as his audio amplifier. that might help others who want to try the It was a 30 -watt job that gave him a nice same system. signal, but the lowest impedance he could The Ground System. First of all, we match was 500 ohms. Since his ground re- found that the two grounds should be as sistance was approximately 20 ohms, he far apart as possible. Most fellows won't needed a transformer with an impedance be able to locate the ground rod more than step-down ratio of 25. Knowing that the a hundred feet away from the point where turns ratio is equal to the square root of the water pipe enters the earth, but that's the impedance ratio, he looked around the good enough, and even shorter distances junk box for a transformer with a turns will work okay. ratio of 5 to 1. He found just what he Also, the grounds should be as good as needed in an old power transformer with possible. You won't need to improve the a 600 -volt secondary. By hooking the mod- water pipe ground-Ts pretty good already ulator's 500 -ohm output to the high -voltage 88 POPULAR ELECTRONICS

AmericanRadioHistory.Com secondary winding of the power transform- are still higher -frequency noise components er and the 117 -volt primary winding to the which ride through with the signal. We did two grounds, he got a good match from the not try supersonic signal frequencies with modulator to the load. appropriate filters and amplifiers at the When improvising matching transform- receiving end, however; this might be an ers, it is useful to check the actual power interesting field for experiment. developed across the load to be sure the Incidentally, hooking a mike instead of match is right. We did this by measuring an audio oscillator to the amplifier gave us the a.c. voltage across the two grounds an easy way to use voice to compare notes while the key was closed. In the case of the on code practice. Phone signals were fair

Block diggram of the 'through - WATER the -earth" communication system. PIPE '=GROUNDS

KEYy 9

"S^ ° AUDIO AMPLIFIER HEADPHONES

I I

MATCHING TRANSMITTER TRANSFORMER (IF NEEDED) RECEIVER

-GROUND RODS-.

modulator, we measured 25 volts across the but naturally not as strong as c.w., and only 20 -ohm grounds. Ohm's law (power equals stations close to each other could use this voltage squared divided by resistance) indi- mode of operation. cated that the amplifier was developing full Operational Range. We learned that power (31 watts) across the load. the idea of communicating through the Installation Tips. There is very little earth was not a new one. In fact, the that can be said about the receiver setup French used a similar scheme with spark since it is so simple. Any set of headphones coils rather than audio amplifiers during will do. The same grounds that are used for World War I, and hams used the method transmitting will serve for receiving, pro- to a limited extent when they were forced vided that a send -receive d.p.d.t. switch is to leave the air during World War II. Nev- employed. However, we found it better to ertheless, the principle has not been used use two separate ground systems. This widely enough to be familiar to a large method assures that the amplifier will al- number of experimenters. Perhaps this is ways be loaded, eliminating the risk of due to the limited communication range of ruining an output transformer by operating the system. into an open circuit. The question of how much range can be Also, a separate ground system for re- covered with an earth communication sys- ceiving permits monitoring your own send- tem is hard to answer because there are so ing and the use of break-in, which is a lot many variables. Based upon our experience of fun in net rag -chews. The receiving with moderate power and simple ground grounds need not be as elaborate as those systems, I would say that a mile radius is for the transmitter. We use single rods the outside limit with only headphones as located some distance from the transmit- a receiver. We copied a weak signal at this ting "antenna" so that our own signals arc distance with 50 watts of transmitter power not deafening in the headphones. in soil which was predominantly clay. On We experimented with receiving ampli- the other hand, with improvement in the fiers, but they don't help since the noise in signal-to-noise ratio through the use of the earth is amplified along with the signal. supersonic frequencies, amplifiers, and Filters to discriminate against the 60 -cycle filters, it might be possible to extend the noise are not fully effective, either, as there range to several miles. -j3p- July, 1960 89

AmericanRadioHistory.Com e Amplifier- Preamplifier T E R

E oN --F... siv á4. _ _^+"`y`-

Lafayette KT -250A delivers 25 watts per channel, provides equalized inputs for phono, tape, or tuner

IF you haven't yet "gone stereo"-or if you're looking for a "best buy" to replace your present stereo amplifier-the Lafay- ette KT -250A kit is a good bet. An integrated stereo amplifier -preamplifier, it has equalized inputs for magnetic or crystal as well as inputs for phono and tape head, OUTPUT a tuner and an "auxiliary" source. Its output matches 4-, 8-, and 16 -ohm speakers, and there's a third -channel output which furnishes a monophonic blend of both "e" stereo channels. If you really want to raise OUTPUT the roof, you can, feed this third output to an auxiliary monophonic amplifier. With a pair of fixed -biased EL86's in the output of each channel, the KT -250A provides 25 watts stereophonically or 50 watts monophonically. Simple switching allows four different modes of operation- reproduction of either channel through both Ganged "separation control" varies amplifiers, normal stereo, reverse channel, the amount of cross -coupling between "A" and "B" amplifiers to re- and reverse phase. duce exaggerated stereo effects. Each channel has its own bass and treble controls. Corresponding controls for the two channels are concentrically mounted, and the volume controls can be clutched to serve as a master gain control for both channels. A touch of a switch and the volume controls become loudness controls for low-level listening.- The measured frequency response of the unit was within 1.5 db from 20 to 20,000 cps and IM distortion was 1.3% at 20 watts output per channel. Hum and noise was down 72 db on the tuner input and 48 db on phono. Sensitivity for full output was .5 volt on tuner and 3 millivolts on phono. The KT-250A is available from Lafayette Radio, 165-08 Liberty Ave., Ja- maica 33, N. Y., for $74.50; a fully wired model (LA -250A) is available for $99.50. 30 90 POPULAR ELECTRONICS

AmericanRadioHistory.Com Ham Bands By HERB S. BRIER N W9EGQ PUTTING UP ANTENNAS

MOST hams quickly learn the importance of Mi a good antenna system in getting more than mediocre results from a ham station. But some don't learn until too late that putting up an antenna improperly can be the most dangerous thing they ever do. The following items which appeared in midwestern news- papers in recent weeks tell the story. "South Bend, Ind. Two teen-age brothers, one of whom had just received his new ham license, were killed last 4. night when the antenna they were erecting fell against a 12,000 -volt power line. A witness said, 'It was like a dozen Roman candles going off all at once.' " "Chicago. Two 16 -year -old boys, pals since grade school, were electrocuted last night while stringing a ham antenna between two trees. They tied a wrench to one end of the wire and threw it over a power line. One boy held on one end of it, and the other boy grabbed the other end of the wire to pull it." High -Voltage Power Lines. Do not discount the chances of getting tangled up with 12,000 volts because you think there are no high -voltage power lines in your neighborhood. You may be right, but don't bet your life on it. There are a lot more high voltages floating around the utility lines along our streets and alleys than most people suspect. The average utility pole has at least three power lines with about 4000 volts between them and 2300 volts between each one and ground. What's more, to satisfy the constantly increasing demand for electrical power to operate air conditioners, electric stoves, and the like, power companies are replacing these 4000 -volt distribution systems with 12,000 -volt lines (7200 volts to ground). In addition, there are often high -s oltage lines on the poles for street lights and other special services. With such high voltages around the utility lines, there is just no safe way to erect an antenna over or near them. Even if you did manage to put an antenna up without getting killed, the antenna would land in a maze of high

July, 1960

AmericanRadioHistory.Com voltage if it ever fell, and this voltage would a live wire. Never depend on the insulation be brought right into your ham station via on outside power lines; after years of being the antenna feed system. exposed to varying weather conditions, it A Safe Installation. For absolute safety, just can't be trusted. no antenna should ever be erected over a If the power lines across your yard make power line. However, if we followed this your antenna problem difficult to solve, rule, few of us would have any antennas at don't hesitate to discuss the problem with all, since there aren't many backyards with- a representath a of the power company. out at least one set of power lines carrying You will probably be pleasantly surprised 115 or 230 volts to our homes. Fortunately, at the help and cooperation you receive. you can still put up a safe antenna system, Keeping the Antenna Up. Just as im- in spite of power lines, by exercising ele- portant as getting your antenna up is keep- mentary precautions-and by making sure ing it up. This is not too difficult. Use at not to string an antenna over a line carry- least No. 14 copper -clad steel or No. 12 ing more than 230 volts. copper wire (enameled) for the antenna It's best to have a plan of operation be- proper in conjunction with antenna insula- fore you start climbing. Your antenna tors strong enough to stand the strain. should be measured and preassembled with Usually you have to contend with a lot its insulators and feed line attached. Then more than merely the combined weights of you won't have to measure it and put it the antenna and feed lines, especially when together while hanging precariously on the they are covered with ice or snow and the top of a pole with the antenna wire draped wind is blowing. over a couple of power lines. Twist all connections tightly and solder Wear heavy work gloves, preferably of them carefully. When the antenna is sup- rubber. Their insulating qualities may save ported by a tree, place a strong coil spring your life if you should accidentally touch between the antenna insulator and the tree

Tom Moss, W4HYW, is a c.w. and radioteletype operator for the Third Army at Fort McPherson near At- lanta, Ga. As a ham, he has held practically all A.R.R.L. offices and is now Vice -Director of the Southeast- ern Division. He is also active in R.A.C.E.S., having served as Deputy Director of the Atlanta C. D. W4HYW covers all ham bands from 1.8 to 148 mc. He uses separate amplifiers capable of a maximum power input of '750 watts on each band, driven by a variety of low - power transmitters. He also runs a Nam of the Month separate 500 -watt phone transmitter; the modulator on this rig doubles as a modulator for the v.h.f. finals. The equipment in his shack is rounded out with an SSB exciter, an electronic keyer, and RTTY and test gear. Tom's antennas include a Mosley 20/15/10 meter tri-bander, an "all -band" doublet and a vertical for the lower frequencies, plus separate rotaries for the v.h.f. bands. Since 1951, Tom's major ham activity has been as manager of the K4/W4 QSL Bureau. Each month he handles a barrage of DX cards. He manages to keep them flowing to their destinations as long as the "4's" keep him supplied with stamped and addressed envelopes. However, he constantly has a backlog of several thousand unclaimed DX cards on file. Tom is something of a DX man himself and an award chaser as well. Top man in the world-wide "Award Hunter's Club," he has over 107 recognized amateur awards to his credit.

92 POPULAR ELECTRONICS

AmericanRadioHistory.Com Transmitter crystal selector (left) holds up to ten crystals, two fitting in each of five octal sockets. For clarity, +he schematic below shows only two of +he sockets and +heir connections to switch Sla/SIb.

MOSIEY PLUG N0. 301 PI to absorb excessive strain on the antenna as the tree sways. Arid use heavy weatherproof rope or strong rustproof wire for GROUND your antenna halyards. TO BOX SEE TEXT CRYSTAL SELECTOR A crystal -controlled transmitter can be frus- trating when you want to be able to change frequency quickly to get "on top" of that "rare socket is grounded (as in the Globe Chief one" calling CQ. With the plug-in adapter 90A or the Heathkit DX -20), then ground shown here, you can select any one of ten the rotor of S1b. Alternately, you can use crystals by just turning a knob. In effect, a single -pole, 11 -position switch (Centralab this gives you a sort of crystal -controlled PA -1001 or equivalent) instead of the VFO. double -pole unit. If you decide on the The unit is built on a standard 3" x 4" x 5" single -pole switch, ground one lead from aluminum box (Bud AU -1028 or equiva- the 300 -ohm line and pins 1 and 7 on each lent). Standard octal tube sockets (SOl- octal socket; but keep in mind that this S05) are used as crystal sockets; each one limits the adapter for use only with trans- accepts two crystals. Note that octal mitters having one side of the crystal socket sockets 503, SO4i, and S05 and their con- grounded. nections to switch terminals 5 through 10 Connect a short length (about 12") of have been left off the schematic diagram 300 -ohm line to the rotors of Sla and Slb, for clarity. or to the rotor of S1a and ground, depend- Two circuits are possible, depending on ing on the circuit used. This line is ter- the type of transmitter you have. Switch minated in crystal socket plug P1 (Mosley Sla/S1b is a double -pole, 11 -position switch 301 or equivalent). Mark the ground pin on (Centralab PA -1005 or equivalent) which PI and the ground pin on the transmitter's can be used for both circuits. If neither side crystal socket if your particular transmit- of the crystal socket in your transmitter is ter requires it. grounded (as is the case with the Johnson To operate the unit, plug P1 into the "Adventurer" or the Knight T-50, for ex- transmitter crystal socket, plug crystals ample), use the circuit as shown without into the octal sockets, and use switch S1 to the ground. select the desired crystal. If one side of your transmitter's crystal (Continued on page 115) July, 1960 93

AmericanRadioHistory.Com By JOHN T. FRYE W9EGV v' Carl and Jerry

Tussle With A Tachometer «u ERE ARE TWO electronic tachometer. Remember we resolved that anything 11 ters we can build for our car," Jerry we put on the car had to be functional." said as he spread a magazine and a little "A tachometer is functional," Carl in- yellow booklet on the bench in front of his sisted. "Knowing exactly how fast the pal, Carl. "This one uses an 884 thyratron motor is turning over is important in many powered by a vibrator power supply. As you cases. For instance, take 'boxwork,' as can see, it's a detailed construction article, we hoity-toity motorists call gear -shifting. and the gadget uses a relatively inexpensive There is one proper engine speed for each 1 -ma. meter as an indicator. shift, and working with a tachometer per- "The other one, in this booklet published mits you to find and use those speeds. Also, by Sylvania, has two 2N233 transistors con- we can log the oil pressure for a particular nected in a one-shot multivibrator circuit. engine speed and use that as a reference Power is taken directly from either a six - later to see if we're losing pressure. We can or twelve -volt car battery. However, about note at what engine speed our generator all we have to go on here is the diagram begins to charge the battery and use this and a very limited description. And this as a check on the generator's operation. tachometer uses a fairly expensive and deli- Wíth a little math that takes into account cate 50-µa. meter." the rear -axle ratio and the rear -wheel cir- "Do both work on the same principle?" cumference, we can convert rpm into "Actually, yes. Whenever a selected mph and check on the accuracy of our spark plug fires, the thyratron is triggered speedometer." into firing or the multivibrator circuit into "Enough!" Jerry interrupted. "I'm con- flip-flopping. Each 'firing' or 'flip-flop' vinced. All that bothers me now is how sends a pulse of current through the meter we're going to calibrate the tachometer." which has a large capacitor connected "Well, just remember that a particular across it. This meter -capacitor combina- cylinder of a four-cycle engine fires only tion responds to the average current pro- once every two revolutions," Carl pointed duced by the pulses. Since these pulses are out. "When the engine is turning over at equal in amplitude and are uniformly spaced, the average current indicated by the meter goes up in linear fashion with the frequency of the pulses. That means the meter can be calibrated to show the rpm of the motor." "I say we build the transistor job," Carl decided, as he finished looking over the two l "We and the articles. have the transistors J ° meter, and we should know enough about electronics not to need step-by-step instructions." "Okay, but before we start, suppose you tell me once more why we need a tachome-

94 POPULAR ELECTRONICS

AmericanRadioHistory.Com 4000 rpm, our tachometer will be receiving that the meter reads 48 µa. when the multi - 2000 pulses per minute-" vibrator is being fed a square -wave signal "I've got it!" Jerry suddenly interrupted. of 40 cps. We can double-check the lineari- "Let's get busy and build the thing. Then ty with square waves of 30 and 20 cps. They I'll show you an easy way to calibrate it." should produce readings of 3600 and 2400 rpm respectively." IT DIDN'T TAKE the boys long to collect "Sounds okay to me," Carl agreed, "but the parts they needed. But Carl and how are you going 1.o be sure you have ex- Jerry prided themselves on making their actly 40 cycles from the generator? The electronic equipment as compact and well - dial calibration is reasonably accurate, but arranged as possible, so they spent con- you can't depend on it down to the cycle." siderable time on layout. Since they real- "That's where the 'scope comes in. We'll ized that the tachometer vould be subjected to intense vibration in the car, they anchored all parts for the multivibrator circuit solidly on a small perforated board of insulated material, and then fastened this board securely inside a small metal cabinet. Two 10,000 -volt capacitors, a neon bulb, and a fixed and variable resistor for attenuating and limiting the high -voltage pulses from the spark plug were similarly mounted in another metal box. Phono jacks on the boxes allowed them to be connected together by a short piece of RG- 58/U coaxial cable. Another length of cable connected the multivibrator unit to compare the 40-, 30-, and 20 -cycle output of the meter, which was shock -mounted on a the generator with the 60 -cycle line fre- bracket designed to clamp on the steering quency with Lissajous figures. Watch." column. Jerry turned on the 'scope and switched "Well," Carl said as he surveyed the on the audio generator, set for sine -wave completed tachometer, "I guess we're ready output. As he approached the 40 -cycle to mount it in the car and calibrate it." mark on the dial, the rapidly revolving pat- "We calibrate it first and then mount it tern of interlaced curving lines slowed down in the car," Jerry corrected him. "Trot out and finally stopped. the sine- and square -wave generator and "See," Jerry said; "a line along the left connect it to the input of the multivibrator side of the pattern would touch three of the circuit while I set up the 'scope." loops while a line across the top would Carl did as instructed, then watched touch two. That means the ratio of the as Jerry ran leads from thé output of signal generator frequency to the line fre- the audio generator to the vertical in- quency is 2:3 or 40:60." put terminals of the oscilloscope and con- When the generator was putting out ex- nected the 60 -cycle test voltage terminal actly 30 cycles, two loops of the pattern on the 'scope to the ungrounded horizontal touched the imaginary vertical line and input terminal. only one touched the horizontal line. At "Here's my idea-double-check me and 20 cycles, only one loop still touched the see if I'm wrong," Jerry said. "Our 0-50 µa. horizontal line, but three Loops touched the meter will indicate 0 - 5000 rpm. That vertical line. means 48 µa. must correspond to 4800 rpm. Jerry went back to the 40 -cycle frequency This reading should be produced when the and switched the generator over to square - multivibrator is receiving 2400 pulses per wave output. As he did so, the distorted minute, or 40 pulses per second. pattern began to wiggle, showing that the "Our square -wave generator should put change in output had caused the generator out a pulse that will trigger the multivibra- frequency to shift slightly. A touch of the tor in the same fashion that the attenuated generator tuning knob stopped the pattern pulse from a spark plug does," he con- again. Jerry reduced the generator output tinued. "All we have to do is adjust the until the meter indication began to fall off calibrating resistor of the tachometer so and move erratically; then he increased the July, 1960 95

AmericanRadioHistory.Com output until the reading was stationary. generator won't go below 20 cycles, it looks "Okay, now set the calibrate control for as though 2400 rpm is the lowest engine a 48 -pa. reading," he instructed Carl. When speed we know is accurate," Carl observed. this was done and the generator set exactly "Wait a doggoned minute!" Jerry sud- for a 30 -cycle output, the meter read 36 denly exclaimed, clapping an open palm to pa. When the frequency was reduced to 20 his forehead. "When the engine is running cycles, the reading dropped to 24 µa. 400 rpm, the tachometer is receiving 200 "Right on the money!" Jerry gloated as shots a minute from a single spark plug. he grinned across at his pal. "The thing is And since all six plugs fire once every two certainly linear over the top half of the revolutions, the coil is putting out 6 x 200 scale at any rate. Disconnect that six -volt or 1200 shots a minute, right?" lantern battery, and let's install the gadget "Right." in the car." "And when the tachometer is recei\ ing 1200 pulses per minute, it reads 2400 rpm. THE MULTI VIBRATOR UNIT was bolted Can you see where I'm heading?" to the metal body of the car up under the "Yeah, I sure can. All we have to do is dash, the attenuator unit was mounted on connect the pickup of the tachometer to the the front of the fire -wall in the engine com- hot lead from the ignition coil and adjust partment, and the connecting coax cable the idle until we get an indication of 2400 was run through a small hole in the parti- rpm. Then we reconnect the pickup to a tion. Connections were made to the rear single spark plug, and if the meter action is spark plug and to the cold side of the ig- linear we should get a reading of 400 rpm." nition switch so that the tachometer would "And 400 rpm is very close to the slowest be switched on with the ignition. When speed we'll need to read. So if the meter in- everything was connected, the boys started dicates correctly there, we can depend on the motor. Then they adjusted the variable it over the whole scale." resistor in the attenuator unit until the The lead from the coil to the distributor was arranged so that a temporary connection could be made to it. Then Jerry adjusted the idle screw until 2400 rpm was indicated on the meter. Next, he used a pair of plastic photography tongs to transfer the input connection of the tachometer from the high-tension terminal of the coil to a spark plug. "What does it read?" he called to Carl. "It might be just a freckle low," Carl said slowly as he peered closely at the meter, "but it's so close to 4 pa. that you can't tell the difference." "Good!" Jerry said with satisfaction.

. E CERTAINLY went to a lot of ,. trouble to make sure this thing was telling us the truth," Carl observed, turning off the ignition. "When it comes to test equipment of any meter gave a steady and unvarying indica- kind, either you have confidence in it or it's tion at a constant engine speed, and moved no good," Jerry remarked. "The time a up and down smoothly as the motor was technician takes to make sure his instru- speeded up and slowed down. ments are accurate is never wasted. Work- "Well, it seems to be all right, but I still ing with a meter whose readings you're not would like to be sure the indication is ac- sure of is like using a rubber ruler to build curate at slow speeds," Jerry fretted. "We a house. But now I've got the connection both know bottom -of -the -scale meter read- back on the spark plug, so what say we taxi ings are often less dependable than those around a bit with our tachometer?" shown in the top half of the scale." "Be my guest!" Carl said, and he opened "Maybe so, but since our square -wave the car door for his friend. -El- 96 POPULAR ELECTRONICS

AmericanRadioHistory.Com XTl1t 21371

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AmericanRadioHistory.Com Shorf - Waive Repo rot QSL

By HANK BENNETT W2PNA/WPE2FT Scott RCH receiver (Navy surplus; 12 tubed, an RME DB-20 preselector, a six - meter Gonset converter, and, for trans- MINISTER, high-school teacher, free- mitting, a Globe Scout 680-A. His "antenna lance newspaper and magazine writer farm" contains 70' and 140' dipoles and a -our featured DX'er this month is all of 225' long-wire. Incidentally, Drayton's RCH these things-and an amateur radio op- receiver, which dates from World War II erator, licensed broadcast engineer, and days, provides continuous coverage from 50 short-wave monitor as well. kc. to 24 mc. Primarily a Presbyterian minister, Dray- Since Drayton returned to short-wave ton Cooper, Edisto Island, S. C.. doubles listening, he has collected a total of 35 as a high-school teacher specializing in veries, covering 20 of 45 countries heard. higher mathematics. He also worked in (Previously he had a total of 100 countries broadcast radio for several years, winding with 98 verified) . He considers his best veri up at WSB, Atlanta, as associate news editor. Drayton developed an interest in radio at the tender age of six (he's now 27 and married). He did some SWL'- ing for a while, then got his f ham license (in 1955) and be- came known on the airways as K4KSY. He is currently one of our outstanding SWL monitors in the southern states. i. Edisto Island is an ideal location for DX'ing; a semi- tropical island off the extreme lower South Carolina coast between Savannah, Georgia, and Charleston, Drayton Cooper, K4SKY, has a minimum of equipment in his SWL S. C., it is in right the mid- corner but he makes good use of it. Radio enthusiast from the dle of "Hurricane Alley." age of six, Drayton is a full-time minister and part-time writer. Drayton frequently provides the only means of communication between the island and the mainland, to be one from HI7T, Santiago, Dom. Rep., especially when the local police net is on 90 meters. Preferring to DX the lower unable to get through on their channel. bands because they "present more of a chal- During hurricane "Gracie" last fall, for lenge," his favorite listening for all-around example, K4KSY stayed on the aír for 44 good programing includes stations in Den- continuous hours. Watch for him on the mark, Switzerland, Australia, and Ger- 75 -meter phone band during the hurricane many. He would like to hear from other season. DX -minded ministers. Included in Drayton's listening post is a (Continued on page 117) July, 1960 97

AmericanRadioHistory.Com witches ial Pc» r irc cif its

By KENNETH RICHARDSON

The common double -pole double -throw (d.p.d.t.) switch has a number of novel applications unknown to the average experimenter. By properly connecting one or more of these switches, you can achieve control over lamp brightness, transformer voltage output, and electromagnet strength.

Photoflood lamps have a comparatively short life span when used on normal line voltage, but connecting two of these lamps in series will greatly lengthen their life. A quick changeover from parallel (normal) to series connection can be accomplished through use of a 10 -amp switch. The series connection furnishes sufficient light to perform preliminary focusing adjustments; switching to the parallel connection delivers full illumination for exposure of the film.

A filament transformer with two 6.3 -volt secondary windings can be used in an experimenter's power supply to provide either 6.3 volts or 12.6 volts a+ the flip of a d.p.d.t. switch. Maximum current output for +he 6.3 -volt output is +he sum of +he maximum currents of both 6.3 -volt windings; the 12.6 -volt output current is limited by the lower current rating of either winding. If voltage output is zero, the secondary windings are bucking each other, and the connections to one of the 6.3 -volt windings should be reversed.

A d.c. electromagnet with two iden- MAGNET tical coils can be varied in strength and polarity by using two d.p.d.t. switches. Switch SI selects either parallel or series connections for the coils. More current flows in the parallel setup, creating a more powerful magnet. Switch 52 reverses current flow, switching +he magnetic poles. Reverse the connections to POLARITY REVERSING one coil if the magnct is weak. SW Ten

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July, 1960 99

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trols . .. all of these deluxe features in a single, compact and handsomely styled unit! Five inputs for each 25 watt channel are provided: stereo channel for magnetic phono cartridge (RIAA equalized); tape head input; three high level auxiliary inputs for tuners, TV, etc. There is also an input for monophonic magnetic phono cartridge, so switched that monophonic records can be played through either or both amplifiers. The automatically mixed center speaker output lets you fill in the "hole -in -the - middle" found in some stereo recordings, or add extra monophonic speakers in other locations. Nearly all of the components are mounted on three circuit boards, simplifying assembly and minimizing possibility of wiring errors. 30 lbs.

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MANUAL STEREO RECORD PLAYER KIT Made by famous Garrard of England, the kD-10 is a compact 4 -speed player designed to provide trouble -free performance with low rumble, flutter and wow figures. "Plug-in" cartridge feature. Rubber matted heavy turntable is shock -mounted, rs.-`.... and idler wheels retract when turned off to prevent flat spots. Powered by a line -filtered, four -pole AD -10 induction motor at 16, 33%, 45 and 78 rpm. Sup- plied with Sonotone STA4-SD ceramic stereo turn- 13395 over cartridge with .7 mil diamond and 3 mil sapphire styli. Mechanism and vinyl covered mounting base preassembled, arm pre -wired; just attach audio and power cables, install cartridge and mount on base. With 12" record on table, requires approximately 15" W. x 13" D. x 6" 1-1. Color styled in cocoa brown and beige. It) lbs. 1~11, a s"Asdrary of [~DAYSTROM, iNcoRr'oRATED Always say you saw it in-POPULAR ELECTRONICS

AmericanRadioHistory.Com ECONOMY STEREO PREAMPLIFIER KIT Although these two new Heathkit models are designed as com- panion pieces, either one can be used with your present stereo system. The preamplifier (AA -20) features 4 inputs in each stereo channel and gives you a choice of 6 functions. It will accommodate a magnetic phonograph (RIAA equalized), a crystal or ceramic phonograph, and two auxiliary sources (AM -FM tuners, TV, tape recorders, etc.) and is completely self -powered. The six -position function selector switch gives you instant selection of "Amplifier A" or "Amplifier B" for single channel monophonic; "Mono- AA -20 $3495 phonic A" or "Monophonic B" for dual channel monophonic using both amplifiers and either preamplifier; "Stereo" and "Stereo Reverse". 8 lbs.

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AA -30 14595 HI-FI RATED 14/14 WATT STEREO AMPLIFIER KIT A tremendous dollar value in the medium power class, this top- quality stereo amplifier -preamplifier combination delivers full 14 watts per stereo channel (28 watts monophonic) to drive your stereo system with ease, while versatile controls give you fingertip command of its every function. In addition to "stereo" and "stereo ' ' ¡ i-`--;:=--" reverse" functions, the SA -2 provides for complete monophonic operation. Inputs on each stereo channel accommodate "magnetic phono" (RIAA equalized), "crystal phono", "tuner" and high level auxiliary input for tape recorder, TV, etc. Other features include a speaker phase-reversal switch, clutched volume controls, ganged tone controls, filament balance controls, and two AC out- lets to accommodate accessory equipment. Handsomely styled in tr`f SA -2 15495 black with inlaid gold design. 23 lbs.

UTILITY RATED 3/3 WATT STEREO AMPLIFIER KIT Your least expensive route to stereo, the SA -3 delivers 3 watts per ' stereo channel (6 watts monophonic), adequate for average living - - room listening. The high level preamplifier has two separate y a inputs for each channel and is designed for use with ceramic or crystal cartridge record players, tuners, tape recorders, etc. Featured are ganged bass and treble tone controls, clutched volume controls, channel reversing switch, speaker phase reversal switch and mono -stereo function selector switch. Attractively SA -3 $2995 styled with satin -black cabinet. 13 lbs.

MIXED LOWS STEREO CROSSOVER NETWORK KIT The AN -10 makes it possible for you to convert to stereo or improve your present stereo system by using just one bass "woofer"; saves buying a second bass speaker, permits using more economical "wing" speakers, improves the bass response of any stereo system. Delivers the non-direction bass frequencies of both channels below 250 cps to a single woofer and passes the higher frequency stereo channels to a pair of wing speakers. Rated at 25 watts per channel. Matches 8 or 16 ohm woofers, 8 ohm high frequency speakers, or Heathkit SS -1-2-3 speaker systems. 10 lbs. AN -10 11 995

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July, 1960 101

AmericanRadioHistory.Com R HEATHKIT9 GIVES YOU MORE IN THESE TEN WAYS :

1. Building a Heathkit is easy-Check-by-step instruction 6. Your Heathki'. is Guaranteed-Every Heathkit unit Is manuals make it virtually impossible for you to tall. guaranteed to meet advertised performance specifica- 2. Building a Heathkit is quick-No complicated, tech- tions . , . or your money will be cheerfully refunded. nical jargon for you to decipher; at most, a Heathkit taken 7. Your Heathkit is available on Convenient Credit- only a few evenings to assemble: Our time payment plan makes it possible for you to order now ... nay later. 3. Building a Heathkit is economical-Mass production 8. Your Heathkit is in and purchasing economies are passed directly along tó Tops Quality-The very finest in you, our customers. electronic equipment comes to you in kit form from the' Heath Company. 4. Building a Heathkit is educational-As yon build,. 9. Heathkit.Dealers can Serye you Locally-Carefully you learn ... more about electronics, more about the selected Heathkit representatives are available in most component units and when and where to add them. localities. 5. Building a Heathkit is fun-Nothing quite equals the 10. Heathkit Service is Customer Service-Our staff of sense of achievement you receive when you successfully technical experts is always ready to answer your ques- complete a Heathkit unit and "tune -in" for the first time. tions or help you if you have any difficulty.

C1 TEN -TRANSISTOR "MOHICAN" GENERAL COVERAGE RECEIVER KIT (GC -1) 1n excellent portable or fixed station receiver. Many firsts in receiver design, ten transistor circuit, flashlight battery power supply and new ceramic IF transfilters. The amazing miniature transfilters used in the GC -1 replace transformer, inductive and capacitive elements used in con- ^r k " " n?-`T-x: :=y ventional circuits for shaping bandpass; offer . superior time and temperature stability, never `` need alignment, provide excellent selectivity. HD -19 " r Telescoping 54" whip antenna, tuning meter, fly- $3495 wheel tuning and large slide -rule dial also featured. Covers 550 kc to 30 me in five hands. $10995 Electrical bandspread on five additional hands cover amateur frequencies from 80 through 10 $11.00 dn., $10.00 mo. meters. Operates up to 400 hours on 8 standard size "C" batteries. Sensitivity: 10 uv, broadcast band; 2 uv, amateur bands, for 10 db signal-to- noise ratio. Selectivity: 3 kc wide at 6 db down. Measures 61/2" x 12" x 10". 20 lbs. HEATHKIT XP -2 Plug-in power supply for 110 VAC operation of GC -1. 2 lbs. $9.95 HD -20 $1 49s

6 -TRANSISTOR PORTABLE RADIO KIT X R-2 P (XR-2 Series) $2995 Unsurpassed quality and styling are combined in (6 lbs.) these handsome sets to provide you with superb and dependable portable entertainment wherever you are-wherever you go! Choose the gleaming, two-tone molded plastic model or the handsome simulated leather-and -plastic combination-both feature a gracefully curved grille in smart beige plastic. The XR-2P complements the handsome grille with a mocha colored case of high -impact plastic, while the XR-2L encases the beige grille in suntan color Sur -U -Lon simulated leather. Vernier tuning control gives you smooth, precise station selection. Six Texas XR-2L Instrument transistors are used for quality per- HW-19 (10 meter) $3495 formance and long life; a large 4" x 6" PM speaker HW-29 ( 6 meter) with heavy magnet provides "big set" richness (7 lbs.) of tone. Ready to play after simple assembly- $3995 transformers prealigned. Six flashlight batteries used for power (50(1-1,000 hrs.) (Batteries not Oafl, included).

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New! One switch operation MUTUAL CONDUCTANCE TUBE TESTER (TT -1) "HYBRID" PHONE PATCH KIT (HD -19) The impressive list of its features make this tube tester a fine value. Tests Gm Transfer calls from ham rig to telephone (amplifiers) from 0-24,000 micromhos, by flipping a single switch! Allows voice `t b' Emission, Leakage, Grid current (% l _e control (VOX) or manual operation. VU et 0- d' ,T, ,A microampere sensitivity), Voltage reg- meter monitors output to 600 ohm line 4 ulators (built-in variable DC power sup - and serves as null depth indicator. Sep- . " 1-'" Low power Thyratron and Eye arate receiver and transmitter gain con- tallow " tubes. Features 300. 450, and 600 ma trols. Provides better than 30 dh isolation TT -1 constant current heater supplies, life test, between receive and transmit circuits. Hybrid tube test, built-in switch operated All leads filtered to minimize RF feed- 113495 calibration circuit. Large easy -to -read back. Matches receivers with 3 to 16 $13.50 dn., $12.00 mo. meter, and constant tension free -rolling ohms impedance. 4 lbs. roll chart mechanism. Individual selector .switches allow testing any tube type, regardless of basepin connections, protect- NEW 100 KC CRYSTAL ing against obsolescence. Assembly sim- CALIBRATOR KIT (HD -20) plified by 7 wiring harnesses and transformer terminal board. Assembly skill of This versatile ham aid provides marker technician or higher recommended, time frequencies every 100 kc between 100 kc 40 hours average. Black leatherette case and 54 mc. Use to align all types of com- with white trim, nylon feet, removable munications equipment. Features tran- top. 27 lbs. sistor circuit dependability, battery power portability, and crystal control accuracy. EDUCATIONAL KIT (EK-1) .005% crystal supplied. 1 lb. Teaches, as you build, the basic "yard sticks" of electronics-opens up fascinat- Two brand new models ing areas of study for youngsters and adults alike. The combination kit and HEATHKIT 10 & 6 METER text -workbook gives you a practical dem- TRANSCEIVERS onstration of the principles of voltage, current and resistance; the theory and Complete ham facilities at low cost! Ideal construction of direct current series and for beginning and veteran hams for local parallel circuits, voltmeter, ammeter and net operations. Transmitter and receiver ohmmeter circuits and the application of are combined in one easy -use -to instru- 's ohms law to these circuits. The completed Features ment. neat, modern styling, meter is used to verify ohms law and the press -to -talk transmit/receive switch, maximum power transfer theorem, one built-in AC power supply, variable re- of the most important theorems in elec- ceiver tuning, variable gain control, and tronics. The finished kit, a practical volt- amplifier metering jack. Operates mobile ohm-milliammeter, may be used in a using vibrator power supply. Microphone variety of applications. Procedures for and two power cables included. Hand- checking home appliances and automobile somely styled in two-tone mocha and circuits included with the kit. The EK-1 beige. Less crystal. will serve as a prerequisite to following VIBRATOR POWER SUPPLIES: VP- , ki; Heathkit Educational kits. Get started 1 -6 (6 volt), VP -1-12 (12 volt). 4 lbs. Kit; - ' EK-1 NOW in this new and exciting series of $8.95 each. Wired; $12.95 each. $1995 "learn -by -doing" educational kits. 4 lbs.

`The convenience of Local Heathkit Sales See Your Heathkit° Dealer* and Service costs but a few dollars more.

July, 1960 103

AmericanRadioHistory.Com Ship -Shaping Marine Radio transmitted as well as the received signals. (Continued from page 61) Bonding all metallic objects together is usually the answer, although a poor bond trical resistances at the connections. A total can aggravate the problem. resistance of only 0.1 ohm in the joints and To obtain maximum range and minimum \vires combined can cause a 1 -volt drop in noise, every channel of your receiver should a 10 -ampere circuit. And, in a 12 -volt sys- be tuned as close as possible to the correct tem, even a 1 -volt drop can cause a signifi- frequency. When you're having trouble on cant loss in transmitter power output and a particular channel, the cure is to replace in receiver sensitivity. The wires should be that channel's crystal with one specifically as short and heavy as possible, and connec- designed for the make and model receiver tions should he tight. you are using. You may have trouble if the Ignition. Receiving range is determined crystal was designed for another type of mainly by the level of man-made noise in set, even if the frequency stamped on it is the vicinity of the receiver. In an automo- correct. If all channels are consistently bile, it's easy to control ignition noise be- noisy, the trouble could he caused by de- cause the engine is enclosed in a metallic fective components in the receiver's i.f. or compartment which acts as a shield. On a audio amplifiers. boat, it is far more of a problem because Many marine radiotelephones are the engine and its high -voltage wiring are equipped with squelch control. The receiv- usually exposed. ing range will be cut drastically if the A commercial suppressor inserted at the squelch is improperly adjusted. With some spark -plug end of each high -voltage line settings, only very strong signals s ill be between the distributor and the spark plugs heard; with others, very weak signals will should do much toward reducing noise. In be heard, but the noise that accompanies the case of a single -cylinder engine, a sup- them will be excessive. By varying squelch pressor inserted in the lead between the settings, you can learn to regulate the effec- ignition coil and the spark plugs is required. tive sensitivity and signal-to-noise ratio of Sometimes it's necessary to use shielded your receiver to meet your requirements. cable (with the shield grounded to the en- Too often, a receiver is blamed when it is gine head or block) between the spark the squelch setting itself that is at fault. plugs and the distributor or ignition coil. Some noise is unavoidable in receivers A special ignition -noise -suppression ca- equipped with automatic volume control. pacitor, consisting simply of a capacitor in- Strong stations will have little background side a metal can, can be installed between noise; but since sensitivity is automatically the input to the ignition coil and the near- increased on weak signals, the noise level est grounded point. Since even the lighting is boosted as well. circuits pick up and re -radiate ignition im- Proper Maintenance. The performance pulses, it may be necessary to install sim- of a marine radiotelephone depends upon ilar capacitors at switches, lamp sockets, the kind of maintenance it is given. Both and other points along the vessel's wiring the transmitter and receiver should be system to bypass ignition impulses to checked thoroughly every few months. ground. Noise caused by the sparking of Tubes and vibrators should be tested and generator brushes can be eliminated by con- replaced when indicated. All transmit and necting a capacitor across the armature of receive frequencies should be measured the generator. with a frequency meter. Receiver sensitiv- If noise persists after all of these precau- ity should be measured, and if found to be tionary measures have been tried, a port- below par, the receiver should be realigned. able transistor radio held close to the ' No license is required to repair or tune wiring will usually pin -point sources of in- a transmitter as long as it's connected to terference. a non -radiating dummy antenna. When con- Other Interference Cures. Poor connected to a "live" antenna, however, a tacts between metal surfaces will some- transmitter can be tuned only by someone times cause metallic objects to act as a rec- possessing a valid first- or second-class ra- tifier or detector, allowing noise and even diotelephone operator license. In all cases, radio signals to mix and form a maze of it is the transmitter's licensee (station li- interference. Vibrating wires also contrib- cense holder) who is responsible to the FCC ute noise and sometimes interfere with the for its proper operation and use. 104 POPULAR ELECTRONICS

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GIANT TUBE -SALE! 7 0D/D to 900/0 OFF! NAMED BRAND TUBES -YEAR GUARANTEE! TYPE SALE TYPE SALE TYPE SALE TYPE SALE TYPE SALE TYPE SALE 024 .50.59 3V4 .69 TYPE SALE TYPE SALE 6AH6 . 1.29 66E6 .63 6CU6 . 183 . .89 4BQ7 . 1.14 6AK5 1.1') 6517 .89 6x8 .89 1216 .67 6BG6G 1.89 60E6 . 1115 . .89 4BZ7 . .69 6557 .79 12ÁT6 .49 125A7 1.12 6AL5 . .53 6BH6 60136 .99 154 . .89 .79 . 1.14 6507 . .79 12Aí7 .84 SAI/IK .95 6AM8 . 12$K7 .89 .89 613115 .99 6J5 . .69 . . 155 .69 50198 . .. 6T4 1.19 12A1J6 .61 12557 .99 650$ . .99 .79 174 . 6BK7A .94 626 .. .79 6T8 1.05 .64 5AQ5 . .63 6AQ5 .62 12007 .79 12SQ7 .89 lU4 . .69 SATE .89 68.7 1.09 6156 .79 608 .99 1200/6 .49 12V6 .59 6455 . .69 6BN6 .84 1U5 . .59 58K7A . I2AV7 .93 12x4 .49 .99 GATE . .53 6606 1.29 1V2 . .57 12AX4 .75 25506 1.29 .81 6AT8 . .91 6807 1X2A . .99 1.09 .69 ST8 . .98 6AU4 . 12Ax7 . .96 6BZ6 .63 20 3AL5 .54 504 . . BUY TUBES TAKE AN 125,7 .99 .69 6AUG . .69 . 61327 1.19 TUBE TESTER 3AU6 .64 SU8 . . .94 12A77 .74 3BCS .69 6AU8 6C4 5)18 . . .93 GAVE. .49 6C136 .66 ADDITIONAL 10% OFF .74 Check 400 tu bes 3BEG .63 5Y3 . 12846' .69 .52 6AW8 . .99 6CD6 1.69 .86 - 1213E6 Wired . 3856 6AB4 . .59 6AX4 6CES .66 .59 $2.49 38Y6 .69 6AC7 . .99 12807 .85 6BA6 . 31326 .65 GAF4 .. .57 6CF6 .72 654 .. .59 6V6 ... .69 1261%5 .99 35C5 .. .59 1.06 6858 . 3086 .63 SAGS .79 1.04 6CG7 .69 65A7 .. .89 GW4 ,., .74 12696 1.29 35W4 .. .49 6BC5 . .65 6CL6 1.04 6SC7 .. .85 6W6 3C56 .68 6AG7 . 6 BC8 ... .79 128Y7 .85 35Z5 .. .55 1.19 . 1.19 6CN7 .74 6527 .. 354 .. .69 . .79 6x4 ... .48 12827 .85 60114 .89 61306 . S005 .. .59 .65 6C56 .64 65/17 .. .84 6X5 ... .59 12096 1.15 5016 .. .89 ORDER BY "BLACK -TYPE" HEADLINES HOW TO ORDER MINIMUM r i.e. 60 II TERMINAL STRIPS -ST ORDER $2 135 EVERETT AVE. AVG. WT. 1 Ib. per pak. State price with each item. Iunlcient postage: excess returned. Send cheek Or M.O. Including CHELSEA 50, MASS. I nclude Postal C.O..U orders, 25 r/c dung; rated, net 30 lays. - Zone No. In address. (Canada postage, 480 lot lb.; 28c ea. add'1 lb.) - .k- July, 1960 105

AmericanRadioHistory.Com Annou nc i ng 1 -- ~-- _ --- The most ------' ix Complete Guide to Hi -Fi and Stereo Ever Published!

In this compact, handy reference, you'll find the answers to nearly any question on hi-fi, plus details and data on trends, components, speakers, stereo, audio theory. Prepared by the Editors of POPULAR ELECTRONICS, the 1960 STEREO HI-FI GUIDE is easy to understand-complete with diagrams, illustrations, and clear explanations. Here's what you'll find in the five big sections of the 1960. STEREO HI -Fl GUIDE:

I. YEARBOOK IV. STEREO Trends and New Products Stereo Standards Multiplex-an analysis and forecast What You Should Know Before Buying Stereo Stereo Simplexing Simplified II. INSIDE THE COMPONENTS Stereo Tape is Back to Stay Detailed analysis of preamps, stereo preamps, Balancing Your Stereo System Stereo Cartridge Directory ' power amps, tuners, turntables, and stereo cartridges Stereo Records-Fad or Fulfillment? III. SPEAKERS AND ACOUSTICS V. AUDIO THEORY AND APPLICATION Inside the HiFi Loudspeakers and Enclosure Maintaining and Testing Your HiF1 Electrostatic and Cone Type Speakers Harmonic Distortion and Networks Does Shrinking Size Mean Shrinking Sound? Filter Crossover Between Speaker and Ear . Custom -Built Equipment Enclosure DON'T DELAY-NOW ON SALE at your favorite newsstand or Electronic Parts Store, or order by coupon today. Only $1.00. 'STEREO. NOW Ziff -Davis Publishing Company ;.111-E1119á Department PE -760 On Sale 434 S. Wabash Avenue, Chicago 5, Illinois Please send me a copy of the 1960 STEREO° HI-FI GUIDE. I or order by enclose $1.00, the cost of the GUIDE, plus 10¢ to cover mailing and handling charges. (Foreign $1.25, plus 25¢ handling coupon today! charges.) Name Only $1.00 Address City ?one State L J

ELECTRONICS 106 Always say you saw it in-POPULAR

AmericanRadioHistory.Com Inside the Hi -Fi Microphone (Continued from page 58) front or back produce an output that depends on how accurately the sound source is centered either at the back or the front. The result is an overall pickup pattern having the shape of a figure eight. Under some circumstances, the bi-directional pickup pattern has great advantages. Unwanted sounds can be minimized simply by facing the mike in a different direction. The balance between sections of an or- chestra can thus be varied quite easily. PORT ARTHUR Single -Direction Mikes. Designers worked for a long time to develop uni- directional mikes and they eventually suc- COLLEGE ceeded using some highly ingenious methods. One of the curious facts of geometry ELECTRONICS COMMUNICATIONS is that the sum of á circle and a figure eight RESIDENT CO-EDUCATIONAL is a figure called a cardioid-a heart -shaped pattern. Combining an omni-directional AM -FM RADIO TV STATIONS mike with a bi-directional mike results in a MARINE RADIO cardioid pattern which is a reasonable ap- proximation to the uni-directional pattern TRAINING Is the finest. Well equipped col- desired. This can be done by building two lege classrooms and laboratories with AM, FM microphones into the same case and then transmitters, radar and marine equipment, col- combining their outputs. (See Fig. 6.) A or fundamentals, transistors, television, camera potentiometer which mixes the outputs of chain, experimental laboratory test equipment, the two mikes in different proportions al- etc. used as standard part of curriculum. lows the pickup pattern to be varied. PRACTICAL On -the -job -training program. Another type of dual -element cardioid College operates Radio Station KPAC, co- microphone is made up of two ribbon trans- owner of KPAC-TV. You learn the interesting ducers. One ribbon is open on both sides way. You learn by doing. and has the typical figure -eight pattern. G.I. APPROVED The back of the other ribbon, however, is totally enclosed in an acoustic labyrinth, CO-EDUCATIONAL You enjoy the personal and has an omni-directional pattern. When growth and cultural advantages that only the American the outputs are combined, a cardioid pat- co-educational college system can tern results. provide. In the RCA 77 dual -ribbon microphone, LOW COST Being a non-profit vocational in- the directional pattern can be changed by stitution explains our low tuit-on rates ... $36 adjusting the opening which leads from per month. Room and board at campus dormi- the back of the second ribbon to an acous- tory only $52 per month. Monthly payments accepted. tical labyrinth. When the aperture is all the way open, the back of the ribbon is also FREE PLACEMENT SERVICE Our graduates effectively open, causing the second ribbon are in demand at good salaries. We have trained men from all 49 states and abroad. INVESTIGATE Write for illustrated booklet P-48 for further details. Classes now forming. Non high school graduates must pass entrance examination. Persons 21 years or older may be accepted on individual approval.

(A) (B) (C) PORT ARTHUR COLLEGE Fig. 6. The most common microphone pickup patterns are omni-directional (A), bi-directional (B), PORT ARTHUR, P-1182, TEXAS and uni-directional, or cardioid (C). When (A) Founded in 1909 and (B) are added algebraically, they produce (C).

July, 1960 107

AmericanRadioHistory.Com to have a figure -eight pattern. When the DX'ing Down Below aperture is closed, the pattern of the second (Continued from page 53) ribbon is omni-directional. This pattern combines with the figure -eight of the first mike orders payable to the Receiver General of to make the cardioid pattern. Other pickup Canada. patterns can be obtained by adjusting the Hundreds of other long -wave stations are opening. included in "Radio Navigational Aids, H.O. The omni-directional pickup pattern of a 205," which can be had for $5.00 from the dynamic mike can be converted into a car- U. S. Navy Hydrographic Office, Washing- dioid shape by controlling out -of -phase ton 25: D. C. pickup and by adjusting various acoustical If you'd like a "sneak preview" of DX'ing impedances in the microphone case. There on the 200- to 400-kc. aero beacon band, you are two general ways of doing this. The can listen to a fascinating new LP record first is to put one or more resonators at that was made aboard an aircraft in flight. the back of the case which vibrate out of It's called "On Course, On the Glide Path," phase with the diaphragm, thus tending to and is produced by Aero-Progress, Inc., prevent the diaphragm from responding to 10493 Santa Monica Blvd., Los Angeles 25, sounds from the side and back. The other Calif. It's complete with an illustrated bro- technique is to provide several small open- chure, and should make an ideal reference ings at the back air chamber to permit the guide for any DX'er. It sells for $5.98 plus acoustical impedances to be varied and thus 25 postage. change the pickup pattern. Some manu- Why don't you put on your electronic facturers prefer to manipulate the charac- diving helmet and plunge into the kilocycle teristics of an omni-directional mike when depths? As you pass that last standard they design a cardioid microphone rather broadcasting station at the bottom of the than build two microphones into one case dial, you'll enter a new world. Come on in, and then combine their outputs. 30 the DX is fine! 30 Hors You Can "GET ON THE AIR" ithout An EXAM! NEW Class "D" Citizens Radio Handbook Answers ALL Your Questions About: How to use two-way radios for business and pleasure-to talk from car to car, ship to shore, office to mobile unit, between farm buildings, on hunting trips, and dozens of other useful applications. HERE'S how to get the most out of your Class transmitters, receivers, antennas, power re- D Citizens Band Radio Set-how to buy quirements, and gives you full instructions for how and use equipment for the ultimate in fun and is stallation and maintenance. Tells you your set and includes practicality! This new, hilly illustrated, easy - and where you can use to -read hook tells you, in layman's language, complete FCC rules and regulations. Contains EVERYTHING the Citizens Bander needs to 130 clear simply -written pages and 72 informa- know. Contents include what to buy and how tive illustrations: only $1.95 plus few cents tch it will cost...which set will suit your fur shipping. FREE 7 Day Trial -Send no needs best...how to apply for your free license money! Mail coupon at once. (no FCC examination required). Discusses Mail Coupon TODAY for 7 DAY FREE TRIAL Examination! ELECTRONICS BOOK SERVICE A Division of the Ziff -Davis Publishing Co. CRE76O 434 South Wabash Avenue, Chicago 5, Ill. Please send me copies of CLASS D CITIZENS RADIO 'and bill me only $4.95 per eopy plus a few cents postage. If I ant not pleased with the book. I may return It within 7 days and I will owe you nothing. r CllEClg IIERE AND SAVE MONEY. I enclose payment for and will pay the postage. (Same 7 -day return j con talk m bookls) herewith. you ,-...Ul hom o ogre to tor, hoot or ' privilege.) ^ , any moving r vehicle on Clans D Citizens -t . Band Radio. And you can send and PRINT NAME receive on Citizens Bond without 4' ADDRESS passing on FCC examination! '4 CITY ZONF STATE N.Y.C. Residents, Please add 3% Sales Tax.

ELECTRONICS 108 Always say you saw it in-POPULAR

AmericanRadioHistory.Com Magnetic Amplifiers (Continued from page 75) The TRUTH About long the lives of the submerged tubes. This is important because lifting the cable to ELECTRONICS JOBS! replace a damaged tube costs thousands of High -pay positions await you in Electronics- dollars. fastest-growing major industry in U. S. 1,500,000 Long -Life Switching. Basic magnetic employed-more needed! Huge demand for trained men in missiles, rockets. electronics, outer - amplifier circuits can he modified to give space projects. Also in Radio-TV service, broad- special effects. For example, a magnetic casting studios, communications. Real opportunity to which has if you prepare now, this easy, low-cost way. FREE excessive positive feedback book tells all! been applied becomes "bistable." This means that it is stable in only two states Get this valuable of operation: maximum output or minimum book now .. . output. There is no in-between. The amplifier is adjusted so that the core is normally in a non -saturated state. But even the -w TREE tiniest input signal-perhaps only a few microamperes-will throw it into complete saturation. Thus it becomes the equivalent 11 of an extremely sensitive switch, or relay. But a magnetic amplifier is a switch without moving parts or contacts, and it is . virtually indestructible. The bistable mag- in netic is beginning as Future to find widespread use ¡q Your a,._ a replacement for relays where long, relia- I ELECAT ble service is great of importance. PP roveRONIdforCSVeterans Several automotive companies-the Ford Your Chance for High -Pay Career: Motor Co., for example-are now using magnetics to control the flow of parts in the I would like to send you my FREE book shown above. It will. tell you all about the Electronics - engine assembly line. First, proximity Radio -Television field . show you the many switches containing magnetic amplifiers high -pay careers open to trained men . . . and explain how you can qualify yourself in a mini- sense the presence or absence of necessary mum of time, at a minimum of cost. Home study parts on an automated line. Other mag- or resident training. Demand for electronics specialists greatly exceeds the supply. Just check the netics, cued by the proximity switch, supply positions held by these recent Central Graduates the parts as needed. Since there are no picked at random from our files: moving components and no contacts, these Garry Sheley, ELECTRONIC TECHNICIAN, Jack Frazier, EN- magnetics show no signs of wear after Convair Astronautics; STUDIO GINEER, Station KM TV-TV ; Alvin Brazda, millions upon millions of operations-long STAFF ASSISTANT. Sandia Corporation; David after normal relay contacts would have Winkler, PUBLICATIONS ENGINEER, Martin Company. Over 50,000 successful graduates since worn out. Another series of magnetics con- 1931!/ 1 L. Foster, President trols the speed of the engine assembly conveyor, to determine the proper produc- /-.Clii/ppaand Mail Today! 1 tion rate. II ELECTRONICS DIVISION-Central Technical Institute The uses for magnetic amplifiers are al- 1 Dept. A.70, 1644 Wyandotte St, Kansas City 8, Mo. most limitless. They serve as memory (Offering engineering technician curricula accredited units by Engineers Council for Professional Development.) in computers and as speed regulators in I Please tell me more about how your training can qualify ME for a high -pay Electronics career. steel, paper, and textile mills; they control (Check specific field(s) of interest below, if you gun turrets and radar antennas on navy I wish.) 1 Radio Guided Missile Tech. Drafting ships; they regulate the voltage output of Television 13 Nuclear Power Armed Forces huge turbine generators; they control auto- Color TV O Radar Civil Service II Electronics Aviation Your Business matic elevators, mine hoists, power shovels, ' Other cranes, and printing presses. In short, Nome wherever the considerations of precise, re- 1 Address liable, trouble -free control are important- 1 City Zone .CCR.RDITED by from jet aircraft to atomic submarines- 1 State County MenlbolYtional you'll find magnetic amplifiers working 11/ Age Education silently and efficiently. 30 L _-111

July, 1960 109

AmericanRadioHistory.Com Extend Life of Records. 'BUILD THE WITH THESE 19 PROJECTS (Continued from page 79) DESCRIBED IN THIS changer arms to track at a uniform stylus ISSUE OF pressure and playing angle, and there's also a greater chance for your records to do PRODUCTS themselves damage by grinding dust and POPULAR grit into each other's grooves. ELECTRONICS Regardless of whether you play your records on a turntable or a changer, bring the unit to a complete stop before you put "Build a Picnic Speaker" Use BUD CU -2107A-$1.50 records on it. Don't grind those delicate record grooves against the moving surface "Crystal Selector" of the table. Also try to get into the habit Use BUD AU -1028-$1.37 of slipping the records you've played back "Unlicensed Two -Way Radio" into their jackets before you settle down for Use BUD WO -6-$12.05 more listening. "Radioman's Lamp" The Dust Problem. No matter how Use BUD AC -402-$1.17 careful you are in handling your records, "Build an Earphone Booster" you still have to cope with the problem of Use BUD CU-3001A-6IC keeping them free of dust. Records start to All Bud products are available for imme- collect moment they diate delivery from your Authorized Bud dust almost from the Distributor. They are the best for applica- leave the stamper at the factory, mainly tions described in these projects. because they bristle with static electricity WATCH FOR THESE LISTINGS EVERY MONTH which attracts airborne dust with tre- IN POPULAR ELECTRONICS mendous speed and efficiency. Recently BUD RADIO, INC,. some of the record manufacturers have 2118 East 55th Street Cleveland 3, Ohio started to add a static -eliminating agent to Dept. P.E. the record "mix," but the great majority of records reach your living room with a good To build the static charge on their surfaces. projects in The time to attack the problem of static this electricity is before you play the record for issue Utei iede the first time. If you wait until it has been of g' played a few times, the dust attracted by STANCOR its static charge will already be partially POPULAR TRANSFORMERS ground into the grooves. Simply brushing the record off with a ELECTRONICS rag won't get rid of the dust attracted by static electricity. On the contrary, it will probably build up the static charge even more. A damp, soft cloth will usually do Sorry a satisfactory job, but for best results you need one of the products specifically Nothing This Month designed for static elimination. Anti -static products include treated Transformers are specified only cloths, sprays, and even mildly radioactive when they have been verified for capsules which clip on to your tone arm their application in the construc- and de-staticize the surface of the record as tion projects listed in this issue. it plays. Both cloths and sprays do the job pretty well, but their effects are not LOOK FOR this helpful list- t permanent. Sprays have their . disadvan- ing every month. It appears reg- tages, too; an overenthusiastic. user can ularly in Popular Electronics. apply such a healthy layer of spray that it will gum up the record grooves and the CHICAGO' STANDARD stylus as well. TRANSFORMER CORPORATION Probably the easiest anti -static products = 3501 W. Addison St. Chicago,` Illinois to use are the radioactive types, either at -

110 Always say you saw it in-POPULAR ELECTRONICS

AmericanRadioHistory.Com Inched to the tone arm or imbedded in a special record brush. With these gadgets, your records can be conveniently de-static- FREE CAREER ized at each playing, and you can count on a year or two of use before having to re- BOOKLET place the radioactive clement. Incidentally, you should always "billow'' the record jacket when you're sliding a Trepare 1°r CAREER record in or out of it to prevent the surfaces 1n of the record from rubbing against the in- ,a,ilaCC ring side of the jacket-and thus increasing the amount of static electricity build-up. Also, the glassine -type inner covers are very efficient static electricity generators and should be deposited in a nearby waste basket. Once you've licked the static problem, you'll find it much easier to keep your records free of dust, and those pops and clicks from your loudspeaker will he few and far between. For even better listening, To guide you to a though, you should give your records a bath successful future in every year or two. This will get rid of the abrasive grit that's managed to find its ELECTRONICS way deep down into the grooves. All you have to do is give your records a RADIO -TV very gentle scrubbing with a soft sponge in some lukewarm water that contains a COMPUTERS little sudsless detergent. A quick rinse under the faucet and a wipe with a clear ELECTRICAL sponge-plus a few seconds exposure to the ENGINEERING air-and your records will be clean as a whistle. Try this treatment on one of your This interesting pictorial booklet tells you bow you can prepare for a dynamic career older records to see just how easy and as an Electrical Engineer or Engineering effective it is. The only precaution here Technician in many exciting, growing concerns the record label itself. On a few gelds: brands, the ink will run when it is wet. Al- MISSILES AVIONICS AUTOMATION though this is the exception, it's wise to SALES DEVELOPMENT check ELECTRICAL POWER ROCKETRY and see if the ink is color -fast before RADAR RESEARCH you dunk it into the wash water. Get all the facts about job opportunities, Record Storage. Storing your records length of study, courses offered, degrees is quite simple and involves only a few you can earn, scholarships, part-time work rules of common sense. Keep the records - as well as pictures of the Milwaukee away from radiators School of Engineering's educational and and sunny windows to recreational facilities. No obligation - it's avoid warping, and store them on end on a yours free. shelf or in a cabinet. Don't stack them MILWAUKEE SCHOOL OF ENGINEERING horizontally because the ones on the bottom will suffer from too much pressure and -MALL COUPON TODAY! those on top are likely to warp. Plastic Milwaukee School of Engineering sleeves for your records will help seal out Dept. PE -760 1025 N. Milwaukee St., Milwaukee, Wis. dust, when Please send FREE "Your Career" booklet particularly your record jackets I'm interested in start to crack open with age. Electronics Radio -TV Computers Electrical If you follow the techniques for record Engineering Mechanical Engineering Name..._..._...._._...... _ ...... _.._...... __.._._... Age.. care outlined above, your records should PLEASE PRINT provide like -new performance for a long Address. time. And the slight effort you spend to City...... _ ...... _...... Zone. .._..... State...._._...... _ keep I'm eligible for veterans education benefits. your records in tip-top shape will Discharge dale..._...... _...... _...._ ...... _.... M5-117 pay dividends in listening pleasure. 30

July, 1960 1II.1

AmericanRadioHistory.Com Transistor Topics YOUR COPIES OF (Continued from page 86) POPULAR trot. Company engineers made tip the car by ELECTRONICS ELECTRONICS combining the old and the new-a 1912 ARE VALUABLE Baker Electric teamed with a roof-mounted panel of 10,000 silicon solar cells connected in a series -parallel arrangement to charge the storage batteries of the car's 72 -volt electrical system. The panel, covering 26 :.:.,nr square feet, can charge the batteries in 10 In:tez:rers hours. Powered by a 3 -hp. electric motor, the car is capable of speeds up to 20 mph. But don't rush out to buy your own sun - KEEP THEM NEAT ... CLEAN .. . powered car-this unit is one of a kind, READY FOR INSTANT REFERENCE! and the power panels are not yet in mass Now you can keep a year's copies of POPULAR ELEC- production. TRONICS in a rich -looking leatherette file that makes it easy to locate any issue for ready reference. Spe- Product News. Sylvania's new Type cially designed for POPULAR ELECTRONICS, this handy file-with its distinctive, washable Kivar cover and D-4121 silicon diode has the highest switch- 16 -carat gold leaf lettering-not only looks good but ing rate of any commercially manufactured keeps every issue neat, clean and orderly. So don't risk tearing and soiling your copies of POPULAR ELEC- unit-it's capable of performing up to 500,- TRONICS-always a ready source of valuable informa- 000,000 logic in a fraction of a tion. Order several of these POPULAR ELECTRONICS functions volume files today. They are $2.50 each, postpaid - second when used in computer circuits. It 3 for $7.00, or 6 for $13.00. Satisfaction guaranteed or your' money back. Order direct from: has a switching speed of 0.3 µsec.-three- tenths of one thousandth -millionth of a JESSE JONES BOX CORP. Dept. PE second. And man, that's fast! (Established 18431 The tunnel diode continues to make news. Box 5120 Philadelphia 41, Pa. Here in the U. S., RCA is producing these units in pilot plant And from o quantities. Tokyo comes news that the world-famous Sony plant has started producing them. mEE The International Rectifier Corporation (El Segundo, Calif.) has introduced a new yÓURSTHIS BIG WALSCO series of low-cost Zener diodes. a ELECTRONICS PRODUCTS Featuring new CATALOG! sealing technique, these units are made Send postcard today for your in standard RETMA voltage steps from 5.6 free copy of Walsco's 64 -page to 27 volts. Rated at 10 watts, they sell for Catalog 59 ... or ask for one at your distributor. under $6.00 each. Thermoelectric cooling units designed to maintain constant operating temperatures WALSCO ELECTRONICS MFG. CO. Division of Textron Inc. for transistors have been put on the com- Western Plant: Los Angeles 18, California mercial market. Manufactured by Westing- Main Plant: ROCKFORD, ILLINOIS, U.S.A. In Canada: Atlas Radio Corporation house Electric Corporation (Youngwood, Pa.), they use the Peltier effect (see Tran- MASTER ELECTRONICS sistor Topics, May, 1960). Intensive, highlevel training at this recognized public college prepares you for a successful career in electronics. Fine equip. From the General Electric Company ment-experienced instructors-small classes-personal attention- all college advantages provide excellent learning opportunities. (Syracuse, N. Y.) comes news of a series of Associate in Applied Science Degree in 18 months. Engineering option. Low tuition and living costs. College housing for single high-speed germanium n -p -n switching tran- and married students. Established 1925. FREE catalog. Write sistors, Types 2N1288 and 2N1289. Under TRINIDAD STATE JUNIOR COLLEGE Trinidad Dept. PE -7 Colorado development for over two years, these units operate up to 60 mc. With maximum rat- engineering degree in 27 months ings of 20 volts, they have betas up to 150. asp your chance for a better life. Rapid advancement. Better income. Selling price, in large quantities, is under BACHELOR OF SCIENCE DEGREE IN 27 MONTHS in Elect. (Elec- tronics or Power major). Mech., Civil, Aero.. Chem. Engineering. five dollars per unit. IN 36 MONTHS In Business Administration (General Business. Mete.. Motor Transport Mgt. maim's). Small classes. More professional class That about covers the semiconductor ho,lrs. Well-equipped labs. Campus. Dorms. Modest costs. Year-round operation. Founded 1884. E]ner Sept., Jan.. Mar.. July. Write J. D. story for now. I'll be back next month with McCarthy, Director of Admissions, for Catalog and "Your Career in Engineering and Commerce" Book. more news and circuits. 3670 College Avenue TRI-STATE COLLEGE Angola, Indiana Lou 112 Always say you saw it in-POPULAR ELECTRONICS

AmericanRadioHistory.Com Test Instruments (Continued from page 83)

3. Use an isolation transformer if the receiver under test is of the transformer - less type. 4. Use only the output lead furnished with the sweep generator. Extending the lead with extra wire can change the wave- YOUNG MEN form drastically. AND WOMEN 5. Keep the leads as clear as possible of stages other than those under test. Electronics is the key to your future. 6. Use the lowest sweep generator output Money - Security - Respecr. Two that gives a usable waveform. A generator World Renowned names PHILCO and output ev en slightly too high can distort SPARTAN bring you the finest elec- the curve. tronics training on the newest and 7. Marker pips should also be kept as most modern equipment available to- small as possible to avoid waveform dis- day. Radar - Sonar - Radio -Transistors - tortion. Television-Modulars and Solid State 8. Generally, a better i.f. alignment will Computers. result if the local oscillator is disabled .11 while i.f. is being aligned. il fit 11 t i1 ti ii 11_(C!s!' e 9. Be sure that. both receiver and test O equipment are warmed up for at least 30 minutes before you begin. . - - _-----, 10. Exact bias, as called for in the manufacturer's alignment instructions, is G1 important. If dry cells are specified for bias voltage, make certain you use fresh 7 , ones. Various Models. Sweep generators offer many different features, and naturally come in a wide range of prices. Some instruments have variable internal marker oscillators, for example; others do not. If óu Hurt I4d NOW/ you already have an AM signal generator that can be used as a marker oscillator, you may not need a sweep generator with WHICH CAREER INTERESTS YOU an internal tunable marker. Nevi Electronics Some generators have a wider sweep Jet Mechanic bandwidth than others. There are even a [ Co -Pilot Etgitieer few generators designed for servicing FM [] Commercial Pilot receivers only, but most cover the FM and [] Link Trainer TV bands with room to spare on either end EJ Instrument Mechanic -some are even tunable down through the broadcast band. Excellent sweep generators can be built from kits. They run from around $35 for Director of Admissions the simpler models to about $75 for the Spartan School of Aeronautics more complex units. Wired models cost Municipal Airport Tulsa, Okla. from almost $100 to several hundred dollars. There are also combination signal and Name sweep generators which can perform all Address the functions of both; these, naturally, are Age a little more expensive. Other special units City can be bought with especially high- or es- Zone State.. pecially low -frequency ranges, high output, Spartan Alumni Write George Goodhead P. O. Box 15852 Tulsa 9, Oklahoma or other unique features. 30 a. 113 July, 1960

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A ONE -TUBE FM TUNER FOR LESS THE HOW AND WHY OF SOLDER THAN - $10.00 What kind of solder has the lowest melt- This one -tube FM tuner is so easy to ing point? What type is the strongest? build at such a small price! You'll he When should acid flux be used? You'll amazed at its remarkable sound. find out the answers to these and many other questions in August POPULAR INSIDE THE HI-FI MICROPHONE- ELECTRONICS. Port II Here's Part II of this important series POPULAR . ","° ó" on hi-fi mikes. August POPULAR ELECTRONICS will give you additional ELECTRONI facts on how to .choose and use a hi-fi mike that's perfect for your needs.

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POPULAR ELECTRONICS 434 South Wabash Avenue Chicago 5, Illinois 114 Always say you saw it in-POPULAR ELECTRONICS

AmericanRadioHistory.Com Across the Ham Bands (Continued from page 93) for News and Views CITIZENS BAND Jack Hurray, K3GRE, 1601 Indiana Ave., Monaca, Pa., runs 25 watts to a Heathkit AT -1 ® transmitter. He added the VFO described in "Across The Ham Bands," June, 1959, to es- cape the QRM of the 40 -meter Novice band. area Now he does most of his operating between 7000 and 7150 kc., c.w., although he modulates the AT -1 about 50% with his tape -recorder gets on 20 meters ra amplifier and occasionally is to chat with a few locals. Jack worked only 11 states as a Novice, but his total is soaring now. He receives with a Hallicrafters SX-17, and his antenna is a 40 -meter dipole In the April "Letters from Our Readers," Jim, WSUJN, objects to using a hi-fi amplifier as a ham modulator (described in our January column) on the grounds that its frequency response would cause the signal to take up too much room in the ham bands. But a series capacitor -potentiometer high -frequency attenuator at the output of the amplifier should make it perfectly suitable for ham use. Trial and error while on the air will give you the right values for the attenuator components. Incidentally, reader Frederic J. Mohr in Bayville, N. J., has called our attention to a typographical error in the May Across the Ham Bands. The parts list for the 80 -meter 93 0.0003-µ4. harmonic filter on page gives MOSLEY V . values for Cl and C3. These capacitors should . -274P, be 0.0003-microfarad units. Howie Lawrence, KN1 MFA, 8 Fermoy Heights Vertical Antenna for Ave., Dorchester, Mass., has worked 130 sta- 100% RUST PROOF tions in 23 states, Canada, and Puerto Rico the 11 meter Citizens Band. 360° radiation in two months on the air. He started on 80 pattern for effective communication at any meters, worked his way to 40, and then to 15, where he worked 12 new states in two days. heading when antenna is mounted clear of A Heathkit DX -20 heats his 40 -meter dipole, interacting objects. and Howie receives on a Hallicrafters S -38E. .. Rich, KNOYCP, of St. Louis. Mo., works Radiator and radials are of heavy gauge 40 meters most of the time with his Heathkit aluminum. Fittings and hardware are DX -40 and Knight R-100 receiver. He asked 61ST6 some questions about two meters and a ver- brass, copper and stainless steel. Vertical tical antenna but did not include his address. and radials are each 9' long. Heavy duty If he will furnish it, we will be glad to answer base mount with ccax connector fits 11/4" ID pipe mast. Supplied with Mosley Antenna Coat for protection against salt corrosion. Model V -27 -GP, less mast & RG-8/U coax. Net Price, $34.95 r -r -- --'- -

- Available from most electronic equipment t, distribctors-coast-to-coast. Arlawirkg

Ut. .r4, E Alan Richards, WA2EGA, operates in Flushing, N. Y. 4610 N. Lindbergh Bridgeton, Missouri July, 1960 115

AmericanRadioHistory.Com his letter Fred G. Leisen, WV6HEI, 2674 Friedell Dr., San Diego 10. Calif., in 10 months as a Novice worked 34 states, three Canadians, and Ivor, VK3XB. using a DX -40 transmitter and a National NC -300 receiver. His General license is now on the way. Dudley H. Cohn, KRQEX, 3408 Mulhern Ave., Kalamazoo, Mich., really ran up a record as a Novice with his Heathkit DX -40, Hammar- lund HQ -129X receiver, home -built 15 -meter beam, 40 -meter dipole, and 80 -meter long -

SIX -METER RULE CHANGE The FCC has moved the 100-kc. segment of the six -meter band which is reserved for Al Ham shack of Fred Leisen, WV6HEI, in (c.w. telegraphy) emission only. The author- San Diego. ized segment is now 15, 50.0-50.1 mc., rather 1. with the vertical and a folded dipole serv- than 50.9-51.0 mc. The ruling permitting Al ing as alternate 15 -meter antennas. Doug re- emission only on 147.9-148.0 mc. in the two - ceives with a National NC -109. He has worked meter band remains unchanged. 24 states and considers California on 40 meters his best DX. After just spending an extra $2.00 for postage on duplicate QSL cards, Doug's pet peeve is wire. "Worked All Continents," "Worked All the non-QSL gang. States," and a 20-wpin code certificate deco- rate his shack wall. He has 44 countries G. W. Grove, W1WHL, better known as "The worked with 24 confirmed. Now that he is a Old Connecticut Squire," informs us that the General, Dudley finds the competition a bit Fifth Annual Graveyard Net Picnic will be rougher. But he logged UJ8GG on the low held on July 9 and 10 at Jamestown, Virginia. end of 40 meters the other day Doug Highlights of the event will be "Eyeball" Price, WV2IRW, 59 Mill Spring Road, Man- QSO's, QSL and mobile judging contests, draw- hassett, N. Y., feeds his DX -20 into a vertical ings by the dozens, equipment auctions and on 40 meters and into a 2 -element beam on swaps, a beauty contest for the ladies, and games for the children. Facilities are available for camping, fishing, swimming, and boating. For more information and literature on the event, write to 1, OPULAR Norm Reynolds, K4GKN, 36 N. Lawson Rd., Poquoson, Va. tELECTRONICS Send Steve Richmond. K1JAW, 115 Franklin, Reading, Mass., started as a Novice in 1958 a ems+ POPULAR at the age of 14. He has made the L ,]. "Brass Pounder's League" for his message -handling, has a 30 -wpm code certificate and a pretty ` ELECTRONICS fair 40 -meter DX record. With his Heathkit c DX -20, Knight, VFO, and 40 -meter dipole, Steve has worked Russia, Poland, Sweden, - . -IF-)_, Every Germany, Czechoslovakia, and 47 states. He will be glad to help the would-be hams in his - Month immediate area get their tickets Thomas

name ELUSIVE HARMONIC address In the May issue of POPULAR ELECTRONICS, two errors crept into the article entitled "The Case city zone state of the Elusive Harmonic." One was permitting Bob, a Novice ham, to a 3 years for $10 use VFO. Well, Bob is now back on crystals and working hard for Check 2 years for $7 one: that General ticket. The other occurred in the 0 1 year for $4 schematic on page 71; the 2.5-mhy. r.f. choke Payment Enclosed El Bill Me connected across the antenna terminals should In the U. S., its possessions and Canada. be wired from the right-hand junction of Foreign rates: Pan American Union countries, L2 -R5 to the 150 -ma. meter's top terminal. add .50 per year; all other foreign countries, In the original schematic, the only DX Bob add $1 per year. could get was from his power supply. Many Mail to: POPULAR ELECTRONICS I thanks to our readers who pointed out these Dept. PE -76, 434 S. Wabash Ave., Chicago 5, III. mistakes.

116 Always say you saw it in-POPULAR ELECTRONICS

AmericanRadioHistory.Com M. Gooding, K4LHB/WPE4TW, P. O. Box 91, Oakton, Va., has been running five watts to a 6AQ5 on 7175 kc., and working such areas as t' Leo 1i Meyerson, WQCFQ, Says Florida, California, and Indiana. Tom's regular pay only 10% down transmitter is a Globe Scout -65 driving an 813, s 1 and his receiver is a Hallicrafters SX-28. He . ,on these would like to compare notes with other experimenters who have low -power transmitters Citizens Band Radios Howard W. Epley, KN7KPM, Route 2, Box 263, Winlock, Wash., asks: "What's this about a sevens He will sked 'Where are the club?'" GLOBE g ELECTRONICS anyone on 15 meters for his first "7" or Wash- ge ington contact. In two months on the air, Howard has worked 46 states, Canada, Wales, NEW Sweden, Southern Rhodesia, Japan, and GIVES Johnson Adven- Pocketphone Puerto Rico. His tools are a YOU turer transmitter, a Hallicrafters SX-100 re- only $1250 ceiver, and a home -built two -element beam. down Carl O. Baptiste, HH2BC, Jacmel, Haiti, W. I., reports that his friend, Jean Sorel, P. O. $7.50 Per Mo. Box 555, Port-au-Prince, Haiti, W. I., would like to correspond with sightless amateurs. NOW ATE /WUAP/ Mr. Sorel, who is a successful lawyer, lin- guist, and teacher, would like to become a I1tIit& latrA 6 111 ham himself and then help other blind people Actual Size 11/4x23/8x61/4 join our hobby Jeff Speiser, K1LDD, 254 W. 234 St., New York 63, N. Y., a student Range 1/2 to 1 Mile at M.I.T., is interested in contacting anyone Handy Paging System with information on the CRP-46ADA radar Requires No License receiver. He also wants to locate persons in r the New York or Boston areas interested in New portable high styled two-way radio 10 astrono- that actually fits into your pocket. Ex- the 3- and -cm. ham bands-radio clusive "power-pak" rechargeable battery my, moon bounce, etc. lasts a year or more. For factory, sur- How about your letter, pictures, and com- veying, construction, department stores, stock -yards, hospitals, firemen, police- ments for next month? 73, golf, .office, and home. Herb, W9EGQ men, $125.00 Each AAAAAAAAAAAAAAAAAAAAAAAAAAA Short -Wave Report CB -200 Sz1saleag//i efee4P/ 97) (Continued from page Especially designed for the commercial u and consumer desiring more Rugged unit. Five crystal controlled achannels for transmitting. The following is a resume of the current Four crystal channel receiving plus one tunable position over entire band. Adapted for selective reports. All times shown are Eastern Standard calling system. Dual conv,sion eliminates in- and the 24 -hour system is used. At time of terference. Absolutely quiet. compilation all schedules given are correct. Size: 37/ex12x1O1/9. $179.95 each. Stations often change frequency and/or schedule with little or no advance notice. CB -100 all reports to P. O. Box 254, Had- Please send Complete 3.rham,el 2.way station for permanent donfield, N. J., in time to reach your Short - installation or travel. Only 31/25101013. Easy to install, operate. Only 3 controls. Range Wave Editor by the eighth of each month. 15 miles. Complete with one set crystals, push Albania-ZAA, Tirana, has been carrying an to -talk microhone, 5129.95 each. English segment at 1730-1758 on 7157 kc. French precedes this at 1700. (WPE1AAC, EMI 111111 MI WPE3NF) I Antigua-Radio Antigua, British West In- WORLD RADIO LABORATORIES dies, has been found on 3255 kc. from 1758 WRL 3415 W. BROADWAY PHONE 32 8-1851 with tuning signal and s(on at 1800 in English. COUNCIL BLUFFS, IOWA A recorded music period with some request tt 1 1845 LEO: PLEASE SEND ( ) TALKABILITY numbers followed to when the signal FOLDER ON THE GLOBE CITIZENS BAND faded. Does anyone know the power? RADIOS. (WPEOAE) Argentina-LRA, Radio Nacional, Buenos Aires, is beamed to Central Europe on 15,345 NAME kc. at 1400 in Spanish, 1500 in German, 1600 in Italian, 1700 in French, 1800 in English, and ADDRESS 1900 in Portuguese, to Eastern N.A. on 9690 kc. 2100 in and 2200 in English, and & STATE: at Spanish PEPjCITY -7 to Western N.A. on 9690 kc. at 2302 in Spanish and 0002 in English. All xmsns are one hour WI MI I= I~1 July, 1960 117

AmericanRadioHistory.Com long. (WPEIAMW, WPEIBD, WPE3EX, WPE9AHC) Australia-Here is the latest schedule from R. Australia (all English except where noted) . SELL YOUR USED To S. and S.E. Asia: 1714-0900 on 25,735 kc.; 1714-0415 on 21,540 kc. (Indonesian at 0100- EQUIPMENT Through 0230) ; 2130-0230 on 21,600 kc. (Saturdays only -sports service); 1714-0230 on 17,840 kc. (In- POPULAR ELECTRON ICS' donesian at 1714-1815. French at 1815-1915, Indonesian at 0100-0230) ; 1714-1915 on 15,210 ° Classified Columns! . ' kc.; 1714-1930 on 15,320 kc. (Indonesian at 1714-1815, French to 1915) ; 0100-0445 on 15,160 kc.; 0429-1230 on 11,740 kc. (Indonesian at 0429-0600, Chinese to 0800, Thai at 0830-0930) ; 0829-1000 on 11,760 kc.; 0459-1230 on 9580 kc.; 0429-1230 on 7220 kc. (Indonesian at 0429-0600, Chinese to 0800, Thai at 0830-0930) . In the East Asia and N. Pacific Islands Service: 1559- 1800 on 15,240 kc., 0244-0700 on 11,760 kc., and 0459-0900 on 9630 kc. To Mid -Pacific Islands: The 320,000 purchasers 1500-1700 on 15,315 kc., 1930-2030 on 17,710 kc. (French) , 1930-2030 on 15,160 kc. (French) , of POPULAR and 0100-0445 on 11,810 kc. (Saturdays at ELEC- 0244-0445). To S. Pacific Islands: 1500-1700 on 11,840 kc., 1815-1915 on 21,680 kc. (French), TRONICS are always and 0100-0415 on 11,710 kc. To N.A.: 0714-0815 on 11,710 kc. (East Coast) and 1014-1115 on kc. interested in good used 11,810 (West Coast) . To United Kingdom and Europe: 0100-0230 on 11.710 kc. To Africa: 2329-0045 on 21,680 kc. The DX program is equipment or compo- aired Saturdays at 1700, Sundays at 0030, 0215, 0800, and 1100. (WPE4BC, WPEOAE) nents. So, if you have Bahamas-If you have never logged these islands, look for ZNS, Nassau, in the broadcast band at 1540 kc. DX'ers along the East something to sell, let PE Coast should have little trouble finding this one during evening hours. (WPE4JP) readers know about it Bolivia-A new station is R. Guavira, Santa Cruz, 9200 kc. It was noted at 1858-1930 with Spanish anmts, good music, and frequent ID's. through our classified (WPEOAE) CP27, 9444 kc., La Paz, has two English columns. It costs very programs: "At Close of Day" at 2105 on Thursdays and a religious program daily except little: 501 Tuesday and Sunday at 2100. This sta- just a word, tion, now powered at 400 watts, is expected to increase to 10 kw., according to Harold Hill, including name and ad- Director. (FB) Brazil-ZYN31, R. Soc. da Bahia, Salvador, dress. Minimum mes- 1525 kc., is noted at 1500-2300, replacing 11,875 kc. There is severe QRM from Lisbon (beamed to Brazil) until 2100. (WPE4FI, WPE9KM) sage: I 0 words. The best time to log the experimental college station on 17,725 kc. 'is around 1800 on Saturdays or Sundays. Otherwise, this station is. on an irregular schedule. (WPE9KM) PRN9, La Voz da Policia Federal, Rio de Janeiro, is to have an English DX program put on by the Brazilian DX Club. Dates and times have not been given as yet but the frequency should be 9295 kc. Pennants will be awarded for correct reports. (WPEIBY) Canary Islands-Two stations currently being heard are R. Atlantico, Las Palmas, 9490 kc., with 'For °cÁ ; Martin Lincoln English on Saturdays at 1800- 1900, and EA8AB, Tenerife, 7295 kc., at 1724- POPULAR CS. 1820 with talks in Spanish and some jazz mu- information ,; One Park Avenue sic. Contrary to schedule given in World Ra- ° dio Handbook, the broadcasting write: ,, New York 16, definitely N. Y. runs past 180d. (WPE3NF, WPE8BGF) Cook Islands-ZK1ZA, Rarotonga, 4965 kc., 118 Always say you saw it in-POPULAR ELECTRONICS

AmericanRadioHistory.Com is on the air Wednesdays only as 2327-0030 with native music. The IS is island drum COMPLETE SERVICE TRAINING beats. (WPE6EZ) written so you can understand it! Curacao-Here is another country that few ... have logged. Look for R. Curom, Willemstad, 9654 kc., at 2000-2230. This is all -Dutch but you may be able to log it by carefully listening for the ,ID. (WPE4FI) Dominican Republic-A new station is R. De- portiva Tangica, 6250 kc. Previously heard on 6200 kc., it has been noted at 1730-2100 and later. (WPE3NF, WPE9KM) El Salvador-A letter from YSEB, San Sal- vador, states that its affiliate, YSDR, Santa Only $13 Ana, has a new outlet on 4800 kc. with slogan for the complete of R. Tropical. Reports go to Apartado Postal 2 -volume course 1006, San Salvador. (WPE3HP) Finland-Op Yleisradio Ab, Helsinki, operates to Europe at 0400-0600 on 6120 ke. and at 1100-1330 on 6120, 15,190, and 17,800 kc.; to N.A. Sept. 23 to March 20 at 0630-0900 (DX program Saturdays at 0630-0700), March 21 Ax any TV or Radio to Sept. 22 at 1530-1800 (DX program Fridays at 1530-1600) on 15,190 and 17,800 kc. The DX program alternates weekly with "Musical Mailbag." (WPE9ADY, WPEOSS) Formosa-The Voice of Free China has Eng. Ever Made daily at 2030-2045 and 0505-0550 on BED7, 7320 kc., BED6, 11,815 kc., BED57, 15,345 kc., BED58, 17,755 kc. (WPEIBD, ET) No complicated theory or mathematics! These famous Ghirardi France-Paris is strong on 7280 kc. at 0100- books get right down to brass tacks in showing you how to handle all types of AM. FM, and TV service work by approved 0145, beamed to the Pacific Islands and dual professional methods. Almost 1500 pages and over 800 clear to 9560, 17,765, and 21,580 kc. illustrations show how to handle every phase of troubleshooting (WPE6EZ) and servicing. Each book is co-authored by A. A. Ghirardi whose Germany-Cologne operates to Eastern N.A. manuals have helped train more servicemen than any other books at 1900-2200 and to Western N.A. at 2200-0100 or courses of their kind! on 11,795 and 9640 kc.; to Eastern N.A. at 1-Radio and Television Receiver 1715-1845 on 15,375 and 11,795 kc. and to West- ern N.A. at 0000-0130 9735 TROUBLESHOOTING AND REPAIR on and 11,945 kc. A complete guide to profitable professional methods. For the German lessons are given at 1815 on 11,795 beginner, it is a comprehensive training course. For the experi- 15,375 enced serviceman, it is a quick way to "brush up" on specific and kc., and at 0100 on 9735 and 11,945 jobs, to develop improved techniques or to find fast answers kc. Test programs have recently been heard to puzzling service problems. Includes invaluable "step-by- step" troubleshooting charts that snow what to look for and to West Africa at 1300-1400 on 15,275 and where. 820 pages, 417 illustrations, price $7.50 separately. 17,875 kc. (Eng. news at 1330) ; to So. America at 1620-1630 on 15,275 kc.; and to Central 2-Radio and Television Receiver America at 1920-2000 on 9605 kc. The latter CIRCUITRY AND OPERATION two xmsns are in German and Spanish. This 669 -page volume is the ideal guide for servicemen who realize it pays to know what really makes modern radio -TV (WPE2AXS, WPE2BFB, WPE2BMO, receivers "tick" and why. Gives a complete understanding of basic circuits and circuit variations; how to recognize them at a glance; how to eliminate guesswork and useless testing in servicing them. 417 illus. Price separately $6.75. Special low price . .. you save $1.25 If broken into lessons and sent to you as a 'course." you'd regard these two great books as a bargain at $7"S or more! Under this new otter, you buy both books for Only $13.00 you save $1.23-and have the privilege of paying easy'sy install- ments while you use them! No lessons to wait for. You learn fast- and right! ' -' STUDY 10 DAYS FREE! - Dept. PE -70, RINEHART & CO., Inc. 232 Madison Ave., New York 16, N. Y. Send books below for l0 -day FREE EXAMINATION. In 10 days 1 will either remit price Indicated (plus postage) or return books postpaid and owe you nothing. O Radio & TV Receiver TROUBLESHOOTING S REPAIR (Price $7.50 separately) Radio & TV CIRCUITRY & OPERATION (Price $6.75) Cheek e for, MON COMBINATION OFFER Sher o oenl$y1.$213.0SenodrN . poe $14.25 You sav $1.25.) Peable at rote of $4 plus postage 1 month for 3 months until fthe t total) of $13.00 has been paid.a SAVE! Send cash with order and we pay postage. Same return privilege with money promptly refunded.

Name

Address

Allyn M. Lamb, WPEOSN, does his DX'ing in City. Zone. State Outside ü.S.A.-.$8.00 for TROUBLESHOOTING & REPAIR; Wichita, Kansas, with a Hallicrafters S-85 receiver, for CIRCUITRY nd&d OPERATION; for both. Cast; $7.25b rn$14..00books a 100-kc. calibrator, rfot0 and a Heath QF-I multiplier. tf t R to r t - ~ ~ ~ - ~ - - - - -.11 July, 1960 119

AmericanRadioHistory.Com WPE2YK, WPE3AJC, WPE3BBM, WPE3DS, CODE WPE4BC, WPE4MF. WPE6PG, 1VPE9KM, been WPEOTA, VE3PE6Y. EC. WK) I have teaching Code LR for forty years turd I know ` Greece-Athens is good on 11,718 kc. with that before you can read Code s/on at 1800. It can also he heard on 11,718 you must first learn the Code alphabet according to SOUND. and 15,345 kc. with English news at 1230. Doialash is not A. The SOUND (WPE8BGF, WPE9KM) resulting front doldash is A. Regiu.dless of discouraging Honduras-A new outlet may be La Voz de ecperienee to the contrary learning ('otle is extremely Suyapa, 4940 kc. Good from 2100, it should easy and fascinating. II dues not have to be third not be degree punishment. \ly automatic transmitter is really confused with the Suyapa outlet on :: ulonlalic. In a matter of seconds you select .lust at 6125 kc. (WPE9KM) fete letters, an entire lesson, any number of lessons Iceland-A letter from TFJ gives the sched- or entire record of seven lessons engraved in copper and your selection will Ile automatically transmitted ule as 1600-1700 daily and 0815-0915 on Sun- over and over with no slopping or changing anything'. days on 12,175 kc. Reports, accompanied by Let nu' send you the full story. an IRC, should be sent to Iceland State B/C R. G. Miller, TELEPLEX COMPANY Service, Reykjavik, Iceland. tWPEIAAC, 739 Kanner Court Modesto, California WPE1HY) India-All India Radio, Delhi, has replaced 15,105 kc. with 15,180 kc. in the 1445-1545 xmsn to the Middle East. The 15,280-kc. channel is noted well at 0730 with IS, Eng. ID, and opening with news. (WPE10E, WPE3NF, WPE8HF) VACATION Special Bargains! Israel-4XB31, Voice of Jerusalem, 9009 kc., COMPLETELY has extended the Eng. xmsn to 1515-1600, an TRANSISTOR WIRED increase of 15 minutes. (WPEOEH, VE2PE1H) oP¢ORTABLE Japan-The latest schedule from R. Japan Reg. reads as follows: to S. Asia at 1000-1130 on .:::: 11,965 and 15,325 kc. in Hindi, Urdu, $24.95(stag$19®vPpstagr) Japanese . and English; to Middle East at 1145-1345 on With Built-in Speaker! 11,705, 15,325 and 9675 kc. in Arabic, French, Complete with 9 -volt battery, carrying case, earphone, English and Japanese; Europe II at 1400-1600 speaker, built-in antenna for on 11,705, 15,325 and 9675 kc. in Russian, Ger- suburbs (telescopic for rural). man, French, Italian, Swedish, English, and Satisfaction Guaranteed 6 TRANSISTOR * RADIO Send cash, check or M. O. KIT: t:,vie 30 ties. ,ri. Japanese; to N.A. at 1930-2030 on 17,855 and (plus Postage) Ir's, nse coils. in -anti -out transit..v:ues 15,325 kc. in English and Japanese; Latin Scc o J 8í3 toil p 9e ad vvrket..ln.n,,eti,n...... LEKTRON 135 Everett Ave., Chelsea SO, Mass. , ,,,,,,...... o.,,,, o,.., . .,,,,,,,,,, SHORT-WAVE ABBREVIATIONS anent .\llllotlltcelllellI kw.-Kilowatts 13/C -Broadcasting N.A. North .\ merica .ling.- English QR\1 Station interfer- I L-Identification ence GET IRC--International Reply R. Radio INTO ELECTRONICS Coupon s/off Sign -off \'.T.I. (ratable leads to success as technicians. field engineers. IS Interval signal s/on- -Sign-on specialists In commialleations. guided missiles. computers. radar. Lc. kilocycles .'man-'transmission automation. Basic & advanced courses In theory & laboratory. Assoc. degree In 2!) mes. B. S. obtainable. ECPD accredited. C.Y. approved. Graduates with mui r companies. Start .Seat.. Fein. Dorms. campus. 11. S. ,1'aduates 01. esUiralent. Cntnlog. VALPARAISO TECHNICAL INSTITUTE America I 2200-2300 17,855 Dept. PE VALPARAISO, INDIANA at on and 15,325 ,, ..b., _`e6 kc. in Spanish and Japanese; N.A. and Ha- waii at 0000-0200 on 11,705, 15,325 and 17,825 kc. in English and Japanese; Europe I at 0230- 0330 on 17,855 and 21,620 kc. in English and Japanese; Latin America II at 0400-0530 on I 11,705 and 9525 kc. in Portuguese, Japanese LOOK and Spanish; Australia and New Zealand at ( IQ NO FURTHER ... IF YOU'RE 0430-0530 on 11,800 and 15,235 kc. in English UNHAPPY WITH "HI" HIFl PRICES. WRITE FOR OUR and Japanese; East Asia at 0500-0730 on 11,940 UNUSUAL AUDIO CATALOG. kc. in Japanese; Asian Continent at 0545-0745 KEY ELECTRONICS CO. on 11,705 and 9525 kc. in Chinese, Japanese, 120-8 Liberty St., N. Y. 6 Russian and English; Philippine Islands and Indonesia at 0630-0800 on 17,855 and 15,325 kc. in Indonesian and English; Korea at 0800- 0900 on 9525 kc. in Korean and Japanese; S.E. Asia at 0800-1100 on 11,705 and 9675 kc. in ~ SCIENCE Chinese, Fukinese, Cantonese, Thai, French, ENGINEERING English, and Japanese. General Asian Service ~ Bachelor's degree in 27 or 36 months at 1900-1930, 2100-2130, 2300-2330, 0100-0200, Accelerated year-round program: Aero. Chemical, Civil. Glee., 0300-0330, 0400-0430, 0500-0530, 0600-0630, Mech., Metallurgical, Mathematics. Chemistry, Physics. Modest rate. Earn board. New classes start Sept., .tan., Mar., June. 0700-0730, and 0800-0900 on 15,135 kc. in Eng- Catalog. 2370 E. Washington Blvd., Fort Wayne 2, Indiana. lish and Japanese. (WPE1BD, WPE4BFY, UN, Radio Japan News) INDIANA TECHNICAL COLLEGE Jordan-A station believed to be in Amman 120 Always say you saw it in-POPULAR ELECTRONICS

AmericanRadioHistory.Com 500

ELECTRONIC- . . - ELECTRONIC 1960" - DIRECTORY KITS WHAT THEY ARE! WHAT THEY COST! { l WHAT THEY DO! Yours in the brand new 1960

ELECTRONIC' 1960 DIRECTORY.

Here it is-the only complete, corn- prehensive directory covering the exciting world of electronic kits! It's yours in the 1960 ELECTRONIC KITS DIRECTORY-over 160 pages- listing over 500 kits of all kinds. Each listing gives you manufacturers, specifications, prices, everything you need to know about kits! You'll find such informative features as: GIANT KIT BUILDERS GUIDE Gives you the latest improvements, and innovations in kits...helps you select the right kit... identifies parts for you, too! COMPLETE SURVEY AND DIRECTORY OF: Kits for HI -Fl - make your own amplifiers, preamps, speakers, turntables, stereo control units, and tone arms. Kits for COMMUNICATIONS-Rundowns on kits for oscilloscopes, tube testers, power supplies, transmitters, receivers, transceivers. Kits r Ziff -Davis Publishing Company for EDUCATION-Coverage of radio kits and PE 76 g manyDepartment434 S. Wabash Ave., Chicago 5, Illinois other special projects. Please send me a copy of the 1960 ELECTRONIC KITS DIRECTORY. I enclose NOW ON SALE AT YOUR FAVORITE $1.00 plus 100 to cover mailing and handling charges. (Canada and Foreign $1.25 plus 100 postage). NEWSSTAND OR ELECTRONIC PARTS STORE ONLY $1.00 Name Don't miss 1960 ELECTRONIC KITS DIRECTORY. Now on sale Address at newsstands, electronic parts stores and hi-fi salons! Buy your copy today, or order by using the handy coupon at right. Only City Zone State $1.00. July, 1960 121

AmericanRadioHistory.Com has been noted testing on 11,812 kc. at 0000- 0100 in Arabic. Further checks are being TV PICTURE TUBES made. (WPE3NF) Middle Congo Republic-Brazzaville carries AT LOWEST PRICES English at 0015 on 21,500, 15,440, 11,725, 9730, 10BP4 $ 7.95 16WP4 $12.00 17TP4 $17.00 21EP4 $13.50 and 5970 kc., at 0300 on 15,440 and 21,500 kc., 12LP4 8.50 16P14 9.95 19AP4 16.00 21FP4 14.50 14B/CP4 9.95 17AVP4 12.50 20CP4 13.50 21WP4 14.00 at 0600 on 15,440 kc., at 0700 on 15,420 kc., at 16DP4 12.00 17BP4 9.95 20HP4 14.50 21YP4 14.50 0930 on 17,720 and 21,500 kc., at 1200 on 11,725, 16EP4 12.75 17CP4 17.00 21AP4 22.10 212P4 13.50 16GP4 14.50 17GP4 17.60 21ALP4 15.75 24CP4 23.50 ,,,,1 1,,,,,,,,,,,111,1 1,,,,,,,,,,,,1,,,,,,,,,,,,,,, 11, 1,111111111111111111111111.11.1111111111.13.1.111111111.11.lllll 1111.11 I,1, 16KP4 9.95 17HP4 12.50 21AMP4 15.75 24DP4 24.50 1604 10.95 17LP4 11.50 21ATP4 15.75 27EP4 39.95 16RP4 9.95 17QP4 9.95 21AUP4 15.75 27RP4 39.95 SHORT-WAVE CONTRIBUTORS 1 YEAR WARRANTY Aluminized tubes $3.00 for 21 'r $5.00 for 24' and 27"addi- Stanley Schwartz (IVPEIAAC), Bridgeport, Conn. tional. Prices include the retu n of an acceptable similar tube under vacuum. These tubes are manufactured f mu reprocessed Donald Brison (IVPEI.4MIV), Edgewood, R. I. used glass bulbs. All materials including the electron gun are C. W. Green Pittsfield, Mass. brand new. (WI'ElARL), ALL PRICES FOB CHICAGO, ILLINOIS. Deposit required, Anson Boice (IVPEIBD) New Britain, Conn. when old tube is not returned. refundable at time of return. Alan Roth (WPEIBY), Bridgeport, Conn. 25% deposit required on COD shipments. Old tubes must David Gems Concord, Mass. he returned prepaid. Tubes shipped Rail Express. We (IVI'EJCE), ship to the Continental U. S. and Canada. only. Peter Lukesh (IVPEIDS), Sudbury, Mass. WRITE FOR COMPLETE LIST Steve Ewing (WPEIHY), Atkinson, N. H. Robert Newhart (WPE2AXS), Merchantville, N. J. -PICTURE TUBE OUTLET - Myron Smith (IVPE2BFB), Rochester, N. Y. 2922 MILWAUKEE AVE., CHICAGO 18, ILLINOIS Jim Teeling (IVPE2B.11O), Orange, N. J. Dickens 2-2048 Albert Mencher (WPE2BRH), Bayside, N. Y. Danny Katcher (WPE2C.V1), South Orange, N. J. Allan Tannenbaum (IVPE2CPP), Passaic, N. J. John Lounsbery (WPE2FK). Brooktondale, N. Y. Ed MacDonald (IVPE3AJC),'Malvern, Pa. Walter Schulz (lt'PE3A 1"B), Philadelphia, Pa. C. Small (WPE3BB.1I) Washington, D. C. Donald Campbell (11'I'E3BCF,), Washington, D. C. E Dan Metro (WPE3DS). McKeesport, Pa. FR C. Rene Reixach (IVPE3E.X), Washington, D. Richard Morcroft (IVPE3/IP) Pittsburgh, Pa. Full year's subscription to RADIO SHACK'S George Cox (IVPE3.WF), New Castle, Del. ELECTRONICS CATALOGS Grady Ferguson (IVPE4BC), Charlotte, N. C. Sensational Richard Lane Memphis, Tenn. world's largest and best line I (IVPE4BF1"), Send. coupon at once! See Roger Legge (IVPE4F1), McLean, Va. of electronic equipment. Stereo, hi-fi, ham radio, tapes- Fla. money- Bill Bruner (II'PE4JP), Key \Vest, over 100,000 items for pro or amateur-alt at Jim Miller (IVPE-111F), Dickson, Tenn. 15 no home trial on any item. 1 saving prices. -day -risk Pedro Vasquez (IVPESRB), Irumagawa, Japan (tem- MAIL COUPON' NOW! porary) Jack Stanley (WPE6BAR). Lomita, Calif. Radio Shack Corp., 130 Commonwealth Ave., Boston II. Mass. Dept. 60-11 J. Art Russell (IVPE6EZ)) SanDiego, Calif. Without further request, send latest catalog plus every new Gerhard Kmeth (WPE6PG), Bakersfield. Calif. issue for one full year-all FREE and POSTPAID.. Ron Russell (IVPE6TY) Stockton, Calif. Name Charles Sutton (l1'PE8BGF), Toledo, Ohio Address Dan \Vilt (IVPE411F). Akron, Ohio Watts Post Office Dan (IVI'E811S), Greenwich, Ohio or City.. Zone State John Gontochak (iVPE8RE), Struthers, Ohio Hank Zabielski (WPE8VS) Taylor, Mich. Richard Olson (IVPE9AD1'), Rochester, Dl inn. 55 PLASTIC EXTENDER: Earl Kinmonth (IVPE9.IGB), Joliet, Ill. Pwh Button Alsembl,iF Thomas Savage (IVPE9AHC), Bloomington, Ill. FRÉE Pin -Point APPlirabon' V Won't,Cau?,CauseiSho,ii Robert Klein (IV PE9ARA), Beaver Dam, Wis. s- 'o "No -Noise" "NoNoisé' A. R. Niblock (WPE9KII) Vincennes, Ind. VOLUME CONTROL and TUNER -TONIC John Beaver, Sr. (IFPE(0AÉ), Pueblo, Colo. CONTACT RESTORER tC With Pe,ma.rlm )onald Dlackison (IVPEOAJP), Denver, Colo. R 2nr. Sil. s Cleans 6 ox. can "A little doesa lot!"` Dick Schreiber (WPEOEH), \Vheat Ridge, Colo. .6e. ..: $1. .P ri"'e4$2,25 <.i$3.25º Jerry'IcMahan (WPECSS), Barnes City, Iowa L Gerhardt Martens (1VPEOTA), Frazee, Minn. 0' Insist On Genuine "No -Noise" Products ...,._.- ''" K. Kerber (VEIPE21,), Halifax, N. S. ' ELECTRONIC CHEMICAL CORK a, Yost Que. 0813 0-1ya Donald Druick (VE2PE711), Montreal, Communipaw Ave.' YJersey City.4N, J. Osb Bruce Lawton (VE3PE6Y), Don Mills, Ont. Richard Bendall (VE4PE!U), Winnipeg, Man. Fred Baines (FB), New Glasgow, N. S. NOW= AVIATION WEATHER' REPORTS, Edward Colby (EC), Lynn, Mass. Doug Eggen (DE). Edmonton, Alta. I,N YOUR'CAR Charles Krabek (CK), E. Weymouth, Mass. Be a weather expert! TC-I Weather John Kennedy (1K), Shelby, Ohio Radio receives 24 hour aircraft weather \\ illiam Kosek (IVK), Washington, Pa. reports (200-400 N.C.) on your car radio. Minutes to install, no electrical Halvor Leifer (HL), Navarre, Ohio connections, won't Interfere with .ant Julia Maldonado de Loebel (IL), River Forest, Ill. reception. Nationwide reception. Edward Tilbury (ET), Anchorage, Alaska or $ year guarantee. Send check Send for free Noack (UN), Kelsterbach, Germany money order. 235.20. postpaid. Ulrich illust ated brochure Radio Japan News Boulevard Electronics. 1229 W. ' Washington, Chicago Ill. Dept PE -7 - 5970, and 21,500 kc., at 1310 on 11,725 and 5970 ESSCOIZED-..,'A new term not found in Webster's...: kc., at 1430 on 9540 kc., at 2015 and 2145 on n CB radio gear: Denotes ULTIMATE PERFORMANCE in 11,725 kc. The 21,500-kc. channel is used on EXCLUSIVELY AVAILABLE, the unique super sensitive A selective dual conversion superhet receiver adaptor as described in TOM Sundays only. (WPE2CPP, WPE3AJC, KNEITEI.'S column in the May POPULAR ELECTRONICS. Factory wired -aligned for simple installation in your Heathkit CB -1 Trans- WPE6BAR, WPE8VS, WPEQAJP, VE4PE1 U, ceiver case. Includes effective noise squelch.. 539.95 ESSCOI ZED CB -1 transmitter section. A unique nver ion includes DE, JK, HL) additional III OUTPUT f4W) class C stage & PI Network. It results In fabulous performance. strongest signals an CB band. Factory Morocco-Rabat is heard on 7115 kc. at stallation only Includes'erystal checking...... $29.95 THE ESSCO DUAL GROUND PLANE ANTENNA ,will extnd your XMTil 1600-2200, all -Arabic, and on 7226 kc. at 1740- range because of its :tits gain. Sturdy longlasting elements.. 327.95 ESSCO CB HATS. 58 Walker Street N. Y. C. 13, N. Y. 1800 with French news at 1750 and Spanish 122 Always say you saw it in-POPULAR ELECTRONICS

AmericanRadioHistory.Com We'd like to send you t ese important new books for a 7 -DAY FREE TRIAL EXAMINATION

CLASS D CITIZENS RADIO Leo G. Sands Here is the first complete book on Citizens Radio Operation. Ever since the initial use of 2 -way radiotelephone by police departments, this field has been growing in ' ` CITIENS importance and application. Now, with more than a million vehicles equipped for its use, Citizens Radio is a major phase of the electronics field. This important new volume covers every aspect of the field-its history, rules, and everything about how it works- . L. in seven big chapters with one hundred major sections. You'll learn exactly what Citizens is. WTL- , Radio its applications, what equipment you need, the full story on receiver circuits and transmitters, antennas, installation, and maintenance, full FCC rulings, how to apply for licenses, etc. Many illustrations. $4.95

COMPUTERS AND HOW THEY WORK -. by James Fahnestock Here is a fact -filled ti exciting guidebook to the wonderworld of electronic computers. with more titan 120 `f illustrations and easy -to -follow tables in 10 big chapters. Step by , step, you'll see I and understand the workings of every type of computer ever used. This important new book illustrates the basic principles of computers in methods p1ERS that require no r knowledge of electronics. You'll learn all about computer memories. flip-flops and the binary counting system. You'll learn the mathematical language of computers I 1 where + = 10. Other chapters show you how computers use tubes and transistors to make complex logical decisions in thousandths of a second. COMPUTERS .r. AND HOW THEY WORT( is must reading for career minded students and for electronics S pros who want a more complete knowledge of this field. $4.95 .

THE ELECTRONIC EXPERIMENTER'S MANUAL by David A. Findlay With a few dollars worth of basic tools, and this book to guide you, you can explore the magic of electronics experimentation more completely than ever before. In a few short hours, you'll start your first project. You'll learn about every component in used experimentation, every tool, its function and why it is useel. There are 10 big sections, each covering a specific phase of construction. There's a giant section of projects you can build, test equipment you'll construct and use in your future work. Tire ELECTRONIC ExPERIxtENTI'.R's MANUAL will give you the professional know-how you must have no matter what phase of electronics is your specialty. $4,95

USE THIS CERTIFICATE FOR 7 DAY FREE EXAMINATION

7 DAY FREE ELECTRONICS BOOK SERVICE EXAMINATION 434 S. Wabash Ave., Chicago 5, III. Please send me copies of CLASS D CITIZENS RADIO anal bill me at only When your books arrive, $4.95 a copy plus a few rents postage. I lease send read me copies of COMPUTERS AND HOW THEY WORK, and and enjoy their diver- hill me at only 54.95 a copy plus a 'ow cents postage. sity of contents, the thor- h lease send me conies of THE ELECTRONIC EXPERIMENTER'S titAN UAL. and hill me at only oughness of their $4.95 a copy plus a few cents postage. coverage. If I 11011'1 agree that this is one of the best electronics I've investments Then after seven days ex- ever made. I may return the hook (s) within seven days and get a full refund. amination, if you decide that $ enclosed. (SAVE SIDNEY! Enclose payment with your order and they are not everything you we'll pay the postage.) want, send them back and Name receive a complete refund Address of the purchase price. City Zone State ZPE70

July, 1960 - 123

AmericanRadioHistory.Com news starting at 1800. (WPEIBD, WPE3NF) is given at 1645, 1830; 2300, 0430, 0700, 0800, Neiherlands-Hilversum is now on 11,755 kc., 1000, and 1045. Call letters: 9730 kc., DZH7; replacing 11,915 kc., to N.A. at 2030-2120 (Sun- 11,855 kc., DZH8; 11,920 kc., DZF2; 15,300 kc., days at 2100-2230). (WPE1ARL, WPEICE, DZH9; 17,805 kc., DZI6; 21,515 kc., DZI$. WPE1DS, WPE2BRH, WPE2YK, WPE3AJC, (WPE3DS, WPE5RB, WPE6TY, WPE9ARA) WPE3NF, WPE4FI, WPE5RB, WPE9KM) Senegal-R. Senegal, Dakar, 4893 kc., has Norway-Norsk Rikskringkasting, Oslo, op- English news from its own station sources, not erates to N.A., North Atlantic, and Caribbean a Brazzaville relay. Try for it at 1730 on Sat- areas at 2000-2120 ("Norway This Week" on urdays. (WPE3NF) Sundays at 2105-2125) and to the North At- Sudan-R. Omdurman, Khartoum, has a lantic, West N.A., Pacific areas, and E. Africa new schedule that reads: Arabic at 2315-0030 at 2300-0020 ("Norway This Week" on Mon- (except Fridays), 2315-0600 (Fridays), and days at 0005-0025) on LLM, 15,175 kc., LLK, 0930-1600 daily. To Southern Sudan at 0900- 11,850 kc., LLG, 9610 kc., and LKJ, 6130 kc. 0930 daily, 0300-0400 (Sundays) . English at (WPE3BCE, WPEOTA) 0730-0800 daily. Frequencies are 5039 kc. (20 Peru-Try for R. Continental, 9350 kc., at kw.) , 9600 kc. (7.5 kw.) , and 11,855 kc. (20 kw.) . 2155-2215; dual to R. America on 9455 kc. only (WPE1BY) for Spanish news at 2200-2205. Another sta- Turkey-R. Ankara, has Eng. news and mu- tion noted well at times is R. Loreto on 9530 sic to N.A.. daily at 1815-1900 on 9515 kc. kc. from 2330 to 0000 s/off. (WPE6EZ, JL) A "Mailbag" is given Sundays at 1825-1840. Philippines-Far East B/C Service, Manila, Other xmsns noted from Ankara include: has English at 2300-2330 on 9730, 11,855, 15,300, 0830-0915 on 17,820 kc.; 1330-1415 on 7285 and 17,805, and 21,515 kc., at 0915-1045 on 9730, 9745 kc.; and 1600-1645 on 15,160 kc. 15,300, and 17,805 kc., at 0800-0830 and 1000- (WPE2CNI, WPE3AYB, WPE4BFY, WPE8HS, 1130 on 11,920 and 21,515 kc. English news WPE8RE,WPE9AGB,VE1PE2L,CK,JK) 30

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W Experimenters Amateurs Hobbyists ILKIE TALKIE RADIO SENDING 'SET Extraordinary values await you in government surplus electronic YOUR OWN POCKET SIZE RADIO STATION components. Don't buy anything until you have o "Bargain Talk to any house or ear radio without wiresor Bulletin"; newmaterial for mere dimes on the dollar. Remem- hookups of any kind! Wt. only t/a lb. Size 1," ber, everything is brand new; here are typical values: 2I/2" x 41/2"./ Built-in antenna. 'Break-in" on w Staneor choke, 5.3 by/450 mils. 50 -ohms, 3 KV..12 lbs. $3.89 regular radio broadcasts with "Dial Setter" and MI Pwr xfmr 115/80. 490 t/130. 5/2 & 6.3/3 pot. 9 lbs. 3.19 "Push -to -Talk" switch. Self-contained flashlight 40 meter coil for BC -610-15 oz. 69e 3 for 1.79 hatterles-Power transistor! Talk to radios in Mallory oil fond, 8 mfd/660 AC (1750 DC okay) 3 lbs. 2.39 the same building and to cars or between cars Cathode ray tube, Type 3API-2 lbs. $1.45....75 lbs. 24/18.95 p to cnea block or way-depending on Fil xfmr, 115/60 pm. 27 amps of 6.3 volts 9 lbs. 3.29 local conditions. Non license or permit needed! MI Jennings type VC vacuum toad, 100 mmfd/2O kV 2 lbs. 6.95 Practical and real fun in a million ways. 4.5-5 MC IFs, dual caed tuned -7 oz. 390 3/ .95 -I Guaranteed to work -1 year service guaranteed. Tone arm, Webster AJI replacement arm -1 lb. $1.69...2/2.95 .1 SEND ONLY $3.00-leash. ek. 0,0) and pay= Slo-Blo fuses. type 3,50, 1/32 amp, box of 100... 2 lbs. 2.95 postman only 99.95 plus COD postage or send NI 612.99 for pnstpd. delivery. Shipped complete al WRITE TODAY FOR FREE GOVERNMENT SURPLUS BARGAIN ºairy to operate with Instructions for all kinds BULLETIN operation. Model Radio Talkie is IN P.O. Box 6188 nuof Ni' 1961 yours now-Today! Availablef'u onlyi from' N JOE PALMER Sacramento, Callfornla WESTERN RADIO, Dept. TEL -7 Kearney, Nebr.

One At Our Regular Low Price And Buy ONE CENT SALE Get The Second For Only lc More NEW SILICON 500MA RECTIFIERS* CITIZENS BAND TRANSMITTER (27 SIC) I watt chassis. complete with crystal GENERAL PURPOSE 400 PIV AT 250 MA 114.99 each, taco for *15.1)0. SPECIAL 2 FOR $ 25 FOR $10 CITIZENS BAND RECEIVER chassis tunable throuth all 22 chanpels. Complete ails audio amplifier. $9.00 ea.. two for .91000. AMATEUR BAND TRANSCEIVER (144-148 MCI chassis with dual VIIF triodes rms/plv s/plv rms/piv rmanolv for ,ral k ie-tit kit radiophone. $0.911... two for $10.00. 35/50 70/100 140/200 210/300 SIGNAL BOOSTER chassis for 27 SIC. High gain (2000) double tuned RFpen- 250 350 450 550 tndo a, pld:er. Improves performance of any Citizen Band receiver. Complete with rmspiv ms/` iv rals/Piv plv tune $11.99 each, 2 for $12.00. 280/400 350/500 420/600 490/700 KIT OF PARTS for ASI-FSI-VHF radio receiver. Tunable from 80-200 me. which 650 850 $1.35 includes U.S. satellite frequencies, .58.19 en two for 47.00. 51.10 CONVERTER (Cryaual Controlled) for 27 SIC Citizens Band, Adapts any alndºrd ms/piv rms/ply ns/piv /piv broadcast radio to 27 SIC band. Tunes all 22 channels. Complete with tubes and 560/800 630/900 700/1000 770/1100 crystal. 914.09 each. 2 for $1.5.00. $1.50 $1.70 $2.00 $2.50 LIMITED QUANTITY-NO LITERATURE OR CATALOG Use in F.W,Bridge or F.W.C.T. up to 750ma DC or into 2" s4 Remit in full. Include sufficient postage. No C.O.D.'s. Fins for 1.5Amp. (Orders $5 o e we pay postage 48 states.) VANGUARD ELECTRONIC LABS. Dept. E-7 -Denote 20% for Capacitor Input r Send 250 for Catalogue Fr y & il Order, 948 99thve.,A Nol l 23, N, Y. "TAB" IIIK Liberty St. N. Y. 6, N. Y. Retail StorMe;a 196-23 J1an0.)aica Ave. , Nollis 23,is N. Y. All BAND TRAP ANTENNA'! NEVER FAIL-' Reduces Interference and For ALL Amateur Trans - s Nalsc All Makes Short Itts for 500 MAIL Spy Wade ZONE YOUR Rene cepti Makes World Link Power for Wide Reception Stronger. LinDirect ,Light.Light. Neat, Clearer on All Bands) Wcathcrprool The Post .Office has divided 106 cities into postal Complete JIB shown total len011, 102 ft. will, 87 ft. of 72 ohm balanced (redline. 4t Hi-imta,et molded sealed automatic frequency resonant trees 3 ' delivery zones to speed mail delivery. Be sure to IFr1at.Yaoutjnt rune oder eadndnnd fotrm'rtelesunl.t.FoErsN ALL w r t nn O C ANDI A: L5' zone number when writing to these cities; , CLAatAeTEURSI as ravared V tor Band Eliminates 5 include antennae í01YIRE IIOUSE a 5ÍIEARACE EASY INSTALLATION'junnntced. be sure to include your zone number in your return 80-40-20-15-10 meter bands. Complete 510.95 . I 40.20-1540 meter bands. 54 ft. antenna (beet for aorldnide awl's) 513.95 'I 20.15-10 meter hands. Dual Trop. 24 ft. Antenna 519.95 v address-after the city, before the state. SEND ONLY 53.00 Icas)1. ek.. mol and pay postman balance COD plea Dealeen on arrival or send 1,ll price for postpaid delivery. Available only from: WESTERN RADIO Dept. AEL-7 Kearney, Nebraska ., 124 Always say you saw it in-POPULAR ELECTRONICS

AmericanRadioHistory.Com ELECTRONICS MARKET PLACE Q0a`,

RATE: 50d ner word. Minimum 10 words prepaid. September issue closes July 7th. Send order and remittance to Martin Lincoln, POPULAR ELECTRONICS, I Park Ave., New York 16, N. Y.

CYLINDER and old disc phonographs. Edison Conqueror, Idelia, and Oratorio models. Berliner Gramophones and Zono-o-phones, Columbia cylinder Graphophones, and Coin -operated cylinder Phonos. Want old catalogues and literatue on early phonos FOR SALE prior to 1919. Will pay cash or trade late hi-fi components. Popular Electronics, Box 50, 1 Park Ave., New York 16, N. Y.

ELECTRONICS Kits wired and tested. Cost, 20% kit price. Work guaranteed. Ten years kit building experience assures top results. Write, E. McCann, 52 Summer, Haverhill, Mass. HIGH-FIDELITY FOLDING Pocket Binoculars -2.5x25 mm. Amazing Price, $3.00: Dave Donovan, 7 E. Wilmot, Havertown, Pa. 10 DISTANCE Crystal set plans -25t;; 20 different 50(:, with Transistor experiments, Laboratories, catalog. 1131-L Valota, PRICES? The Best! Factory -sealed Hi -Fi Yes! Redwood City, California. Components? Send for free catalog. Audion, 25P Oxford Road., Massapequa, RADIO and Television Tubes-Brand New, 1st Quality. Top Name N. Y. Brands in original boxes, 60% off list, Free Bonus with orders, DISGUSTED with "HI" Ili -Fi Prices? Unusual discounts on your Prompt Deliveries; U T C-Box 306, Syosset, N. Y. High Fidelity Requirements. Write Key Electronics, 120 Liberty St., New York 6, N. Y. CLoverdale 8-4288. TELEVISION Sets $9.95 plus Shipping-Jones T.V., Sanatoga, Pa. AUDIO Accessories-best prices-free catalog. Audiotone Re- DIAGRAMS for repairing radios $1.00, Television $2.0C. Give cording Services, P. 0. Box 9, Port Washington, N. Y. make, model. Diagram Service, Box 672 -PE, Hartford 1, Conn. TREMENDOUS savings! Sherwood, Dual AR, all others! Im- GOVERNMENT Surplus Receivers, Transmitters, Snooperscopes, mediate reply to your correspondence. Sound Room, 1509 Parabolic Reflectors, Picture Catalog 10C. Meshna, Malden 48, Bedford Avenue, Brooklyn, N. Y. Mass. KITS Assembled: Hi -Fi, Amateur, Test Equipment, Etc. Work- manship Guaranteed. For Details Write Remco, Box 475, AUTO Radio Distributor Selling, Servicing, Becker Blaupunkt, Knoxville, Illinois. FM -AM, other European, American Sets. Save 30% + Square Electronics, 150-60 Northern Blvd., Flushing, New York. GOVERNMENT Sells! Surplus Electronics; Test equipment; Oscil- loscopes; Transceivers; Jeeps; Boats; Aircrafts; Misc.-Send for U. S. Depot Directory & Procedure $1.00-"Government Surplus TAPE & RECORDERS Sales," Box 425 PE, Nanuet, Y. N. í WPE-SWL-CB-QSL Cards-Samples 10C-"Brownie" W3C11, 3110A 1 Lehigh, Allentown, Penna. TAPE Recorders, 1i -Fi components, Steep Learning Equipment, RADIO & TV Tubes at Manufacturer's prices! 100% Guaranteed! tapes. Unusual Values. Free Catalog. Dressner, 69-02F, 174 Brand New! No re -brands or pulls! United Radio, Box 1000-E, St., Flushing 65, N. Y. Newark, N. J. AMPEX, Concertone, Magnecord, Presto, Bogen, Tandberg, Pentron, Sherwood, Rek-O-Kut. Scott, Shure, Dynakit, others, REPAIR Instructions, Schematics, Radios, T.V's, HiFi's, 99C Trades. Boynton Studio, Dept. PE, 10 Pennsylvania Ave., Tucka- Model? "Coop" Box 5938, Kansas City 11, Missouri. hoe, N. Y. CONDENSER checker-opens, shorts intermittents. Accurate, RENT Stereo Tapes-over 1,000 different-all major labels- reliable. Ready to use. Guaranteed! Mesco, Box 4521, free catalog, Stereo-Parti, 811-P Centinela Ave., Inglewood 3, K. C. 24, Mo. California. RECORDERS, CITIZEN Banders increase coverage 100% R. F. cascode ampli- Components Free wholesale catalogue. Carston, fier kit $4.95. Wired $6.95. I. F. Amplifier kit $4.95 wired 125-P East 88, N. Y. C. 28. $6.95. Specify, Make, Model. Money back guarantee. Todd LOW Quotes on everything HiFi & Stereo Tapes., Bargain Lists. Radio 9417-3 Ave., Brooklyn 9, N. Y. HiFi, Dept. P2, Roslyn, Pa. SAVE 100% 2 CITIZEN'S Band! Add a Hushpuppy noise suppressor to your Over Tape -Recorder -speed 71/z"/sec. 33/4"/sec. 5 in. 8 Heathkit transceiver! Squelch Action. Completely Wired. Guar- speaker $49.95 -transistor 2 -Band w/battery, earphone anteed. $4.98. Western Mass. Electronics, Great Barrington, leather case $28.85 6 -transistor w/battery, earphone leather Mass. case $17.85. Check or money order, guaranteed. P. 0. Box 2404, Memphis 2, Tenn. CITIZEN'S Band. Preamplifier Kit, printed high sen- circuit, NEW Patented Tape Threader. Simply attach to end of tape. sitivity $12.95 complete, $22.95 wired. Capri Electronics, 3118 Eliminates pigtail threading. Automatically releases at end of W. 48th, Los Angeles 43, Calif. reel. Holds Loaded reel from spilling. A boon to every tape CAPACITOR Leakage Tester. Checks Shorted, Leaky condensers recordist. Send $1 for 5 threaders. Tunetime Recording Enter- quickly, easily. Guaranteed. Send $14.95 to: Bob's Radio & TV prises, Box 652, Adelaide St. Postal Stn., Toronto, Ontario, Supply, P. 0. Box 149, Wayland, Mass. Canada. CHEMICALS and Apparatus Catalog 25e. Nu -Age Laboratories, Box 232, Bellmore, N. Y.

INSTRUCTION WANTED

-a TRANSISTORIZE your automobile ignition system. Complete plans and instructions: $2.50. Technical Services Institute, CASH for used short-wave Ham Receivers, Transmitters and 5699 -24th Terrace North, St. Petersburg 10, Florida. Accessories. Treger, W91VJ. 2023 N. Harlem Ave., Chicago 35B, TUxedo 9-6429. COMPLETE your high school at home in spare time with 63 -year - old school. Texts furnished. No classes. Diploma. Information WANT to buy good equipment and accessories? Place a low-cost booklet free. American School, Dept. XB63-Drexel at 58th, classified ad in this space. Chicago 37, Illinois. July, 1960 125

AmericanRadioHistory.Com WRITE Martin Lincoln, Popular Electronics, 1 Park Avenue, New BUY direct from factories -Appliances, Cameras, Watches! York 16, N. Y. for information on how to place a classified ad Free details! Cam Company, 6810 PE -20th Ave., Brooklyn 4, in this section. N. Y. POLICE Radar Detector. Stop before those radar speed traps. GROW Mushrooms. Cellar, shed and outdoors. .Spare, full Fool proof, legal system. Complete diagrams and instructions time, year round. We pay $4.50 Ib. dried. We have 29,000 $2.75. C. Carrier Co., 5880 Hollywood Blvd., Hollywood 28, Calif. customers. Free Book. Mushrooms, Dept. 334, 2954 Admiral Way, Seattle, Wash. BE A Spy! Correspondence course on wire tapping, bugging, telescopic sound pickup, recording techniques, microphotog- RADIO Parts Stores & Hi -Fi Salons: Someone "borrowing" your raphy, invisible and remote photography, telescopic and aerial personal copy of Popular Electronics each month? You ought to photography. Lessons in surveillance, tailing, and use of equip- be taking advantage of Popular Electronics' convenient re -sale in a ment. Complete course $22.50. C. Carrier Co., 5880 Hollywood plan. Sell copies your store ... perform good service for Blvd., Hollywood 28, Calif. your customers . with no risk involved. For details, write: Direct Sales Department, Popular Electronics, One Park Avenue, ELECTRONIC Hypnotizer. Simplifies the art of Hypnosis. Dia- New York 16, New York. grams and operating instructions $3.00. C. Carrier Co., 5880 MAKE newspaper for Hollywood Blvd., Hollywood 28, Calif. $25-$50 Week, clipping items publishers. Some clippings worth $5.00 each. Particulars free. National, 2 MAN Submarine. Jet powered. Cheap and easy to build. Con- 81 -DG, Knickerbocker Station, New York City. struction plans and instructions. $4.25. Seaway Electronics, 5880 Hollywood Blvd., Hollywood 28, Calif. 2 WAY Wrist Radio with auxiliary Long Distance Booster. Com- plete construction details $3.00. C. Carrier Co., 5880 Hollywood Blvd., Hollywood 28, Calif. MUSIC JUNK Your Distributor and Voltage Regulator.: Improve automobile mileage and performance. Construction details for transistorized distributor and voltage regulator. No moving parts. $4.75. DB Enterprises, 8959 Wonderland Ave., Hollywood SONGPOEMS And Lyrics Wanted! Mail to: Tin Pan Alley, Inc., 46, Calif. 1650 Broadway, New York 19, N. Y. COLOR TV. Convert your black and white TV to color. Completely POEMS Wanted for musical setting and recording. Send poems. Electronic. No mechanical gadgets. Costs about $35. Complete Free examination. Crown Music, 49 -TM West 32, New York 1. construction details $4.75. DB Enterprises, 8959 Wonderland Ave., Hollywood 46, Calif. ELECTRONICS By sleep teaching. The thorough way to train. Catalog 24¿. Electra -Sleep, 8959 Wonderland Ave., Hollywood 46, Calif. EMPLOYMENT 'INFORMATION EXPERIMENT with nature's electronics! Instructions -Still- water, Box 337 W. Morris Plains, New Jersey. CALCULUS or Algebra, Easy Lessons. First Four $1. Matchco, 4256-8 Minmor, Cincinnati 17, Ohio. OVERSEAS Employment. American firms and United States Gov- job information $2.00. Foreign Op- HIGHLY Effective Home -study Review For FCC Commercial ernment. Comprehensive Box 172, Columbus 16, Ohio. Phone Exams. Free Literature. Write: Chief Instructor, Cook's portunities, School of Electronics, PE7, Box 10634, Jackson 9, Miss. EARN extra money selling advertising book matches. Free samples furnished. Matchcorp., Dept. MD -70, Chicago 32, Illinois. HIGH Pay Overseas, Domestic Jobs, Men, Women. Generous Benefits. Companies Pay Transportation. For info, write: World Wide, Dept. E, 149 N. Franklin St., Hempstead, N. Y: INVENTIONS WANTED PHOTOGRAPHY -FILM INVENTIONS wanted. Patented: unpatented. Global Marketing Service, 2420-P 77th, Oakland 5. Calif. EQUIPMENT, SERVICES INVENTIONS Wanted, patented: unpatented. J. T. Invention Sales Company, 25 Fayette St., Brooklyn 6, N. Y. Math Bargains Request Free Giant Catalog TURN Your Ideas -Inventions into cash, royalty. Ketchum's OPTICAL Science "C1" 128 pages Astronomical Telescopes, Microscopes, Advertising, B -1058-I, Springfield, Illinois. - - Lenses, Binoculars, Kits, Parts. Amazing war surplus bargains. Edmund Scientific Co., Barrington, New Jersey.

MISCELLANEOUS STAMPS & COINS'

BIRTHDAY, Graduation Gifts for Hams. Brochure. K9TVA, 26. 6429C Glenwood, Chicago 105 DIFFERENT U. S. stamps 25C, Approvals included. Shelron. VOLTAGE Tester Screw Driver Combination $1.00. Naelco, Box Box 907-1, New York 8, N. Y. 182, Mercer Island, Washington. 50 ALL Different stamps -Free with approvals. Wm. Rice, 87 Washington Avenue, Kingston 42, N. Y. SHOPPING. GUIDE LEATHERCR AFT Classified -

AND SERVICES NOT A HANDY REFERENCE TO PRODUCTS FREE "Do -It -Yourself" Leathercraft Catalog. Tandy Leather NECESSARILY ELECTRONIC, BUT OF WIDE GENERAL INTEREST. Company, Box 791-M-34, Fort Worth, Texas.

BUSINESS OPPORTUNITIES MISCELLANEOUS

VENDING MachInes-No Selling. Operate a route of coin ma- FREE! New 1960 catalog of all photographic books available for chines and earn amazing profits. 32 -page catalog free. Park- your copy. Send postcard with name and address to Catalog, way Machine Corporation, Dept. 12, 715 Ensor St., Baltimore Popular Photography Book Service, One Park Ave., New York 2, Md. 16, N. Y.

126 Always say you saw it in -POPULAR ELECTRONICS

AmericanRadioHistory.Com WINEMAKING, Beer, Ale Brewing, Cider. Methods, illustrated, $3.00. Eaton Bookstore, Box 1242.C, Santa Rosa, California. WHATEVER your needs, Popular Electronics classified can solve them. Simply place an ad in these columns and watch your SEN®MG results pour in.

PEN -PAL Specialty Service, 221 West Maple, Viroqua, Wis. Scientific A Interests Matched -25C Free Information. BILL? NEW Mothers' Names! $1.00 per 100. M.A.M., P. 0. Box .;8213, It'll get there quicker you Honolulu, Hawaii (Waikiki Branch). if give KEY chains, personalized ashtrays, smoke sets-Novelties for your postal delivery zone number home, office and gifts. Inexpensive items. Send 10e for illustrated brochure. House of Brand, Dept PE -3, 3458 Fish Ave- with your address. nue, New York 69, New York. The Post Office has divided 106 HOMEBREWED Wines, Beers. Complete instructions-$1.00. Dean's, Box 40 -EL, Elberton, Georgia. cities into postal delivery zones to HOW to pick locks! Illustrated. $9.95 Wilford Publications, 7400 Benjamin Franklin Station, Washington 4, D. C. speed mail delivery. Be sure to BUSINESS Cards $3.75 Thousand postpaid, Free samples, Imagination, Box 761, Hollywood 28, Calif. include zone number when writing GOLF Clubs Wholesale. Free Price List. Crystal Golf Sales, to these cities; be sure Crystal, Mich. to include zone HOMEBREW. Make it yourself. Complete instructions $1.75. your number in your return Homecrafts, Box 587-A, Bellevue, Nebraska. address after the city, before OVER 320,000 buyers and sellers - will read your ad when placed in this space. It costs only 50C per word; minimum of 10 words the state. including your name and address.

Advertisers' Index JULY 1960-POPULAR ELECTRONICS ADVERTISER PAGE ADVERTISER PAGE Airex Radio Corporation 24 National Technical Schools 7 Allied Radio 19 North American Philips Company, Inc. 8 Atlas Sound Corp...... 20 Audio Devices, Inc. 2nd Cover Olson Radio Corporation 28 Blonder -Tongue Paco Laboratories, Inc...... 26 Electronics Company, Inc...... 10 Boulevard Electronics 122 Palmer, Joe 124 Bud Radio 110 Picture Tube Outlet.. 122 Popular Electronics Book Division 108, 123 Capitol Radio Engineering Institute 35 Popular Electronics Book Division Listing.. Central Technical Institute 109 29, 30, 31, 32 Chicago Standard Transformcr Corporation.. 110 Port Arthur College 107 Cleveland Institute of Electronics 25 Progressive "Edu-Kits" Inc. 27 Coyne Electrical School 9 RCA Institutes, Inc. 16, 17 DeVry Technical Institute 5 Rad-Tel Tube Co. 33 EICO 36, 38 Radio Shack Corp. 122 Electro -Voice 15 Rinehart & Co., Inc. 119 Electronic Chemical Corp. 122 ESSCO ...122 Sarkes Tarzian 99 Shure Brothers Inc. 37 Grantham School of Electronics II Spartan School of Aeronautics 113 Sprayberry Academy Heath Company 100, 101 102, 103 of 2adio-Television.... 13 Springfield Enterprises 28 Indiana Technical College 120 International Crystal Mfg. Co., Inc...... 23 "TAB" 124 Teltron Electric Co. 18 Johnson Company, E. F. 20 Texas Crystals 24 Key Electronics Co. .120 Tri-State College 112 Kuhn Electronics 14 Trinidad College 112 Tru-Vac Electric Company Lafayette Radio 22 . 21 Lektron 105, 120 U. S. Air Force 3 United Scientific Laboratories, Inc. 14 Micro Electron Tube Co. 12 Miller, R. G. 120 Valparaiso Technical Institute 120 Milwaukee School of Electronics...... III Vanguard Electronic Labs. 124 Mosley Electronics, Inc. .115 Walsco Electronics Moss Electronic Inc. 3rd, 4th Cover, 128 Mfg. Co...... 112 Western Radio 124 National Radio Institute I World Radio Laboratoriez 117

July, 1960 127

AmericanRadioHistory.Com SHIPPED ON APPROVAL NO MONEY WITH ORDER -NO C O.D. INIVI MOM 111111 ~I 111111 IMO MIN ~I ~I IIIIIIIIIII VIM =MN i Superior's New Model 76 ALL PURPOSE BRIDGE ITs A CONDENSE BRIDGE IT'S A SIGNAL TRACER - IT'S A RESISTANCE BRIDGE Its A TV ANTENNA TESTER CAPACITY BRIDGE SECTION make stage gain measurements, locate loss in 4 Ranges: .00001 Microfarad to .005 Mi- signal R.F. cind Audio. stages, lo- calize faulty stages, locate crofarad; .001 Microfarad to .5 Micro - distortion and hum, etc. farad, .1 Microfarad to 50 Microfarads; 20 Microfarads to 1000 Microfarads. Will V TV ANTENNA TESTER SECTION also measure the power factor of all con- Loss of sync., snow and instability are be densers from .1 to 1000 Microfarads. only a few of the faults which may in the antenna, so why Model 76 ALL PURPOSE BRIDGE RESISTANCE SECTION due to a break BRIDGE not check the TV anrenna first? .Locates Total Price $26.95 2 Ranges: 100 ohms to 50,000 ohms; o break in any TV antenna and measures Terms: $6.95 after 10 day trial, then 10,000 ohms to 5 megohms. the location of the break in feet from $5.00 per month for 4 months if satis- SIGNAL TRACER SECTION the set terminals. factory. Otherwise return, no explana- With the use of the R.F. and A.F. Probes R.F. and A.F. '26ss tion necessary. Complete with Net included with the Model 76, you can probes and test leads

Superior's New Model Tv -50A GENOMETER -. 7 signal Generators in One! I P.F. Signal Generator for A.M. r Bar Generator i.; R.F. Signal Generator for F.M. II Cross Hatch Generator Audio Frequency Generator ' Color Dot Pattern Generator C=,,.© l.._ tl Marker Generator This versatile All -Inclusive GENERATOR Provides ALL «) the Outputs for Servicing: A.M. Radio F.M. Radio Amplifiers Black and White TV Color TV Model TV -50A GENOMETER... The Model VARIABLE AUDIO FREQUENCY GEN- Total Price $47.50 R. F. SIGNAL GENERATOR: TV -50A Genometer provides complete ERATOR: In addition to a fixed 400 10 doy trial, then Terms: $11.50 after for A.M. and F.M. alignment. cycle sine -wave audio, the Model TV - for 6 months if satis- coverage $6.00 monthly Radio Frequencies from 100 50A Genometer provides a variable 300 return, no explano- Generates factory. Otherwise Kilocycles to 60 Megacycles on funda- cycle to 20,000 cycle peaked wave tion necessary. mentals and from 60 Megacycles to 180 audio signal. Megacycles on powerful harmonics.

The Model CROSS HATCH GENERATOR: The Model DOT PATTERN GENERATOR (FOR COLOR TV) BAR GENERATOR: most of your -50A projects an actual Bar TV -50A Genometer will project a cross- Although you will be able to use TV for servicing Color TV, Pattern on any TV Receiver hatch pattern on any TV picture tube. regular standard equipment is a Dot Pattern Screen. Patterns will consist of The pattern will consist of non -shifting, the one addition which is a "must" The Dot Pattern projected on any color 4 to 16 horizontal bars or 7 to horizontal and vertical lines interlaced to Generator. the Model TV -50A will enable 20 vertical bars. provide a stable cross -hatch effect. TV Receiver tube by you to adjust for proper color convergence.

MARKER GENERATOR: The Model TV -50A includes all the most frequently needed marker points. The following markers are pro- The Model TV -50A comes abso- 456 Kc., 600 Kc., 1000 Kc., 1400 Kc., 1600 vided: 189 Kc., 262.5 Kc., lutely complete with shielded leads Kc., 2000 Kc., 2500 Kc., 3579 Kc., 4.5 Mc., 5 Mc., 10.7 Mc., (3579 Kc. is the color burst frequency). and operating instructions. Only

USE APPROVAL FORM ON NEXT PAGE) INTEREST OR FINANCE CHARGES We inviteyout try before you buy any of the models de- .110 scribed on this andthe following pages. If after a 10 day ADDED! you arc completely satisfied and decide to keep the trial to the Tester, you need send us only the down payment and agree If not completely satisfied, you are privileged return to pay the balance due at the monthly indicated rate. Tester to us, cancelling any further obligation. MOSS ELECTRONIC , INC. Dept. D-765 3849 Tenth Avenue, New York 34, N. Y.

128 PRINTED IN u.s.A. POPULAR ELECTRONICS

AmericanRadioHistory.Com TR FO 10 DAYS before you buy! then if satisfactory pay in easy, interest free monthly payments. See coupon below. 1~1 SupeModel82A A truly do-it-yourself type TUBE T TEST S ANY TUBE IN IO SECONDS FLAT! OInsert It Into a num- 0ITurn the filament selector socket as desig- Press down the qual- switch to posi- 2tierednated on our chart 3 ity button tion specified. (over 600 types In- - cluded). O THAT'S ALL! Read emission quality direct on bad -good meter scale. FEATURES: Production of this Model was delayed a full Tests over 600 tube types. Tests OZ4 and year pending careful study by Superior's en- other gas -filled tubes. Employs new 4" meter gineering staff of this new method of testing Model Tester with sealed air -damping chamber resulting in tubes. Don't let the. IOW =rice mislead 2.0111 82A-Tube accurate vibraticadess readings. Use of 22 We claim Model 82A will outperform similar Total Price ...... _...... _ $36.50 sockets permits testing all popular tube types looking units which sell for much more-and and prevents possible obsolescence. Dual es proof, we offer to ship it on our examine Terms: $6.50 after 10 day trial, Scale meter permits testing of low current before you buy policy. then $6.00 monthly for 5 months tubes. 7 and 9 pin straighteners mounted on if satisfactory. Otherwise re- panel. All sections of multi -element tubes Model 82A cornea housed in turn, no explanation necessary. tested simultaneously. Ultra -sensitive leak- handsome, portable, Saddle- age test circuit will indicate leakage up to 5 megohms. Stitched Texan case. Only....Net'36"

SUPERIOR'S NEW MODEL :33 C. R.T. TESTER Tests and Rejuvenates ALL PICTURE TUBES ALL BLACK AND WHITE TUBES ALL COLOR TUBES From 50 degree to 110 degree types Test ALL picture tubes-in the carton- -from 8" to 30" types. out of the carton-in the set! Model 83 is not simply a rehashed black but lacking in proper definition, contrast /[N and focus. To test for such malfunction. off and white C.R.T. Tester with a color 1i©t. adapter added. Model 83 employs a new you simply press the rej. switch of Model improved circuit designed specifically to 83. If the tube is weakening, the meter ©°- _ - test tae °leer type black and white tubes. reading will Indicate the condition. the newer .ype black and white tubes and Rejuvenation of picture tubes is not simply all color picture tubes. Model 83 provides a matter of apply.ng a high voltage to the separate filament operating voltages for the filament. Such voltages improperly applied can strip the cathode of the oxide coating Model 83-C.R.T. Tube Tester older 6.3 t. pcs and the newer 8.4 ty-Des. Model 83 enploys a 4" air -damped miter essential for proper emission. The Model 83 Total Price ...... $38.50 with eualit7 and calibrated scales. Model applies a selective low voltage uniformly to 83 properly tests the red, green and glue assure increased life with no danger of Terms: $8.50 after 10 day trial, sections of color tubes individually-for cathode damage. then $6.00 monthly for 5 months each section yf a color tube contains its !lauded tn handsomeTexportablee if satisfactory. Otherwise return, own flame it, plate, grid and cathode Saddle Stitched Texan case- no explanation necessary. Model 83 w II detect tubes which are appar- complete with sockets for all ently good but require rejuvenation. Such black and white tubes and tubes will pro-ide a picture seemingly food all color tubes. Ossl.v

We invite you to try before you buy any of the models described - on this page, the preceding page and the following pages. If after a 10 day trial you are MOSS ELECTRONIC. INC. completely satisfied and decide Dept. D-765, 3849 Tenth Ave., New York 34, N. Y. to keep the Tester, you need send us only the down payment Please send me the units checked on approval. If completely satisfied I will pay on and agree to pay the balance the terms specified with no intereit or finance charges added. Otherwise, I will return due at the monthly indicated after a 10 day trial positively cancelling all further obligation. rate. I] Model 76 .. .Total Price $26.95 Model 83.. Total Price $38.50 NO INTEREST S6.95 within 1 0 days. Balance $8.50 within 10 days. Balance monthly for 4 months. OR FINANCE $5.00 $6.00 monthly for 5 months. Model TV -50A Tonal Price S47.50 Model 70... Total Price $15.85 CHARGES ADDED! S11.50 w ithln 10 days. Balance $3.85 within 10 days. Balance monthly for 6 months. $4.00 monthly for 3 months. If not completely satisfied, you $6.00 are privileged to return the Tester to us, cancelling any further Model 80 . Total Price $42.50 Model 82A...Total Price 536.50 obligation. $12.50 within 10 days. Balance $6.50 within 10 days. Balance $6.00 $6.00 monthly for 5 months. monthly for 5 months.

SEE OTHER Name SIDE Address CUT OUT AND MAIL TODAY! city Zone State All prices net, F.O.B., N. Y. C.

AmericanRadioHistory.Com SHIPPED ON APPROVAL NO MONEY WITH ORDER -NO C.O.D. ______I_ _ _ _ CRUM Superior's New Model 70 UTILITY TESTER® FOR REPAIRING ALL ELECTRICAL APPLIANCES t'114_ and AUTOMOBILE CIRCUITS As an electrical trouble shooter the Model 70: Will test Toasters. Irons, Broilers, Heating Pads, Clocks, Fans, Vacuum Cleaners, Refrigerators, '1I Lamps, Fluorescents Switches, Thermostats, etc. Measures A.C. and D.C. Voltages, A.C. and D.C. Current, Resistances, Leakages, etc. Will measure current consumption while the appliance under test is in operation. I Incorporates a sensitive direct -reading resistance range which will measure all resistances commonly used in electrical appliances, motors, ele. Leakage detecting circuit will indicate continuity from zero ohms to 5 megohms (5,000,000 ohms). As an Automotive Tester the Model 70 will test: Both 6 Volt and 12 Volt Storage Batteries Generators Starters Distributors Ignition Coils Regulators Relays Circuit Breakers Cigarette Lighters Stop Light, Condensers Directional Signal Systems All lamps and Bulbs Fuses Ileating Systems horns Also will locale poor grounds, breaks in wiring, poor connections, etc. INCLUDED FREE This 64 -page book-practically a condensed 1 course in electricity. Learn by doing. rModel 70-UTILITY TESTER UTILITY Model 70 comes com- Just read the following partial list of contents: What plete with 64 page book Total Price...515.85- TESTER is electricity? Simplified version of Ohms Law and test leads Terms: 53.85 after 10 day trial, What Is wattage? Simplified wattage charts How to measure voltage, current, resistance and leakage then $4.00 monthly for 3 months, How to test all electrical appliances and motors if satisfactory. Otherwise return, no using a simplified trouble -shooting technique. $1 85 explanation necessary. How to trace trouble in the electrical circuits and parts in automobiles and trucks. Only

SUPERIOR'S NEW MODEL 80 20,000 11,1"ALLMETEE -, THE ONLY 20,000 OHMS PER VOLT V.O.M. SELLING FOR LESS THAN $50 WHICH PROVIDES ALL THE FOLLOWING FEATURES: SPECIFIC OTIONS: .. 6 INCH FULL -VIEW METER provides large easy -to -read calibrations. No squint- 7 D.C. VOLTAGE RANGES ing or guessing when you use Model 80. (At a sensitivity of 20,000 Ohms per Volt) MIRRORED SCALE permits fine accu- 0 to 15/75/150/300/750/1500/7500 Volts. rate measurements where fractional read- 6 A.C. VOLTAGE RANGES: ings are important. ( At a sensitivity of 5,000 Ohms per Volt) CAPACITY RANGES permit you to ac- 0 to 15/75/150/300/750/1500 Volts. II curately measure all condensers from 3 RESISTANCE RANGES: css..e- .00025 MFD to 30 MFD In addition to the 0 to 2.000/200.000 Ohms. 0-20 Megohms. ` K standard volt, current, resistance and 2 CAPACITY RANGES: decibel ranges. 00025 Mfd. to .3 Mfd., .05 Mfd. to 30 Mfd. Model 80 ALLMETER IIANDSOJtE SADDLE -STITCHED CAR- 5 D.C. CURRENT RANGES Total Price $42.50 RYING CASE included with Model 80 0-75 Microamperes, 0 to 7.5/75/750 Allmeter at no extra charge enables you Milliamperes. 0 to 15 Amperes. Terms: $12.50 after 10 doy trial, then to use this fine instrument on outside 3 DECIBEL RANGES: - 6 db to + 18 rib. $6.00 monthly for 5 months if satis- calls as well as on the bench in your shop. 14 db to + 38 db 4 34 db to -I- 58 db factory. Otherwise return, no explona - tion necessary. Model 80 Allmeter comes complete with operating instruc- $4250 lions, test leads and portable carrying case. Only (T1L NOTE: The line cord is used only for capacity measurements. Resistance BEFORE you buy! ranges operate on self-contained batteries. TRY FOR 10 DAYS THEN if satisfactory pay in easy, interest free, monthly payments. See coupon inside. We invite you to try before you buy any of the models described on this and the preceding pages. If ofter a 10 day trial you are FIRST CLASS completely satisfied and decide to keep the Tester, you need send us only the down payment and agree Permit No.61430 to pay the balance due at the monthly indicated rate. (See other New York, N. Y. side for time payment schedule details.) BUSINESS REPLY CARD NO INTEREST No Postage Stamp Necessary if Mailed in the U. S. VIA AIR OR FINANCE CHARGES ADDED! POSTAGE WILL BE PAID BY - If not completely satisfied, you are privileged to return the Tester MOSS ELECTRONIC, INC. to us, cancelling any further obligation. 3849 TENTH AVENUE SEE OTHER NEW YORK 34, N. Y. SIDE ' CUT OUT AND MAIL TODAY!

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