I D I I I e II

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MOBILETTE 61, International's neu. improred all transistor, crystal con­ trolled converter provides a "quick and easy" way to convert your car radio for short wave reception. MOBILETTE 61, units cover a specific band of frequencies providing a broad tuning range. Mobilerte units are miniature size and quickly interchangeable.

Check these all New fea tures ... N ew and improved circuit for increased gain . . .New internal jumper for positive and negative grounds . .. New RF amplifier, mixer/oscillator ... New separate input for broadcast and short wave antennas ... Mounting bracket for under dash installation.

• MOBILETTE 61, is available in a wide choice of frequencies covering the Amateur bands 75 through 6 meters, Citizens band, Civil Air Patrol •• . with improved circuit for mobile short wave reception

low band frequencies, W/W/V time and frequency standards. Any frequency in the range 2 MC to 50 MC available on special order. *

Designed for 12 VDC, Mobilelte 61 units cover these short wave frequencies. Catalog No. Frequency MOBILETTE 61 will op­ 630 - 110 6 meters (Amateur) 50 - 51 MC erate on 6 VDC at reduced 630 - 111 10 meters (Amateur) 28.5 - 29.5 MC 630 - 112 11 meters (Citizens) 26.9 - 27.3 MC . output. Power connector 630 - 113 15 meters (Amateur) 21 - 21.6 MC 630 - 114 20 meters (Amateur) 14 - 14.4 MC plugs into cigarette lighter 15 MC (WWV) socket. 630 - 115 40 meters (Amateur) 7 - 7.4 MC 630 - 116 75 meters (Amateur) 3.8-4 Me See the MOBILETTE 61 630 -117 10 MC (WWV) 630 - 118 CAP (Low Band) at Your Dealer Today. 630 - 119 Special Frequencies 2 MC- 50 MC

Complete, ready to plug in and operate .... only $22.95 *Special frequencies 2 Me -50 MC-.. only $25.95

JANUARY 1961 73 MAGAZINE •I • •

fromiG__ I z'~ .. a comp'ete'y';n:e~w~~:::;;_l CITIZENS BAND that meets. '" TRANSCEIVER FCC regulations

·EICO premounts, prewires, pretunes, and seals the ENTIRE transmitter oscillator circuit to conform with FCC regulations (Section 19.71 SUbdivision d). EICO thus gives you the trans­ ceiver in kit form that you can build and put on the air without the supervision of a Commercial Radio-Telephone Licensee!

- Kit $69.95 #761: 117 VAC & 6 VDC #762: 117 VAC & 12 VDC incl. mtg. bracket (Pat. Pend.)

NEW! 6o-WATT CW COLOR .. MONO DC·5MC LAB .. TRANSMlnER # 723 5 ~ Kit $49.95 Wired $79.95 TV OSCILLOSCOPE # 460 Ideal for novice or advanced ham Ki t $79.95 Wired $129.50 needing tow-power, stand-by rig. 5 ~ PUSH·PULL OSCILLOSCOPE 6QW CW I SOW external plate mod­ -# 425 Kit $44.95 Wired $79.95 ulat ion. 80 through 10 meters. gO-WATT CW TRANSMITTER· # 720 Kit $79.95 Wired $119.95 PEAK·TO-PEAK ·U. S. Pat. No. 0.184,776 VlYM # 232 ..·UNI·PROBE@ " Top Dual ity" - ELE CTRO NI C Ki t $29.95 Wi red $49.95 KITS GU ID E. Ideal for veteran or ·U. S. Pat. No. 2,190.051 novice. 90W CW, 65W exte rnal VACUUM TUBE VOLTMETER # 221 plate modulatio n. 80 through 10 Kit $25.95 Wi red $39.95 meters. HIGH-LEVEl UNIVERSAL MODULATOR·DRIVER -#730 RF SIGNAL GENERATOR # 324 Kit $49.95 Wired $79.95 • (150kc.43smc) Delivers SOW und istorted audi o. Kit $26.95 Wired $39.95 Modu lates transmitters having fY·rM SWEEP GENERATOR RF In puts up to loOW. Un ique It MARKER # 368 cver- mceutetten indicator. Cover Kit $&9.95 Wired $119.95 E-S $4.50. GRID DIP METER # 710 Kit $29.95 Wi red $49.95 DYNAMIC CONDUCTANCE TUBE Incl udes complete set of coils .. TRANSISTOR TESTER # 666 for full band coverage. Continuo Kit $69.95 Wired $109.95 "';ilJ....- ous cove rage 400 kc to 250 me. TUBE TESTER # 625 • 500 ua meter. Kit $34.95 Wired $49.95

EICO, 33-00 N, Blvd.,LI.C. 1, N.Y. 73.1 -= ~hO~~I~eo~ oro ~?q~r~)'~ o~ O ~1~ Name - ~ I ~ro ge:3 ~~~; sJ~~~eC'~r~ rd; Address _ _ ~ I ~~v l ~~dli~:~See . 0~e ~~I: h1~r:~~ Cib' Zone State i I • EI C~I~b:!:~~~e~~.~I~I~O~~~o~~p~a~~~:r_·..:1

2 • 73 MAGAZINE JANUARY 1961 Magazine January, 1961 73 Vol. I, No.4 /379 East 15th Street Brooklyn 30, N. Y. Table of Contents

Nuvistor Converters for Six and Two ...... Tom Lamb K8ERV . . ... ••• • • •••• 8 417A perfo r mance without 417 A cost.

Down With Drift ...... Jim Kyle K5JKX/6 . · .. . . - ...... 12 Step by s tep !!o ta biliza t ion of xcur receiver,

6N2 Completed Don Smith W3UZN · ...... 14 Eico, H ea t h a nd J ohnson kits add up to 100 wa tts on S ix a nd Two.

1296mc ...... Bill Ashby K2TKN . ·...... 16 Secret con felilli on s of a U HF a ddict, Goblin Patrol Bill Lester W8UCY · ...... 18 H ams team up with cops to louse u p H a ll o w ee n lor the k id s .

Lost in a Tunn el Jim Kyle K5JKX/6 · ...... 20 Ploneer tng frust rations of a diode epeiluu ker,

8 me Crystal Modification Kit . • • • • . ... Don Smith W3UZN • •• • • • • • •• • • 24 Fee thee who a rt long on 8 m e rocks ,

Transistorized Frequency Standard • •• •• • •• • ...... Howard Pyle W70E •• • ••• • • • •• • 26 Think of all the edve ntages.

Suction or Whoosh Paul Barlon W6JAT • • •• • • • • • • • • 28 One is better, but you' ll never know which unless you read the a r ticle.

Transistorized Communications Receiver Hans Rasmusen OZ7BQ •• • • • • • •• 30 J ust to show you what you cun do if you reufIy want to.

Vertical Radiator ...... Howard Pyle W70E · ...... 36 To warm the ether, not you r shack .

A-M Deteclors Staff . • • • • • • • •• • • • 40 Our big t echnical article for the month. Gua ranteed both interesting a nd Informetive•

Switch from the T-17 ...... Roy Paffenberg . . .. . •• •• • • • • • •• 51 The fine art of su rplus acavenging.

Propagation Forecast Dave Brown K21GY . ·...... 52 W ha t banda what t ime to where p robably. Spot Frequency Operation of VHF Nets ...... Bob Kuehn WpHKF 54 How to herd everybody onto t he sa m e channe l.

See-Saw Bleeder . • •• • . . Pat Miller KV4CI . 56 Save power lind get better reg u la t ion t hisa way.

Misc.: Stoll: Feble of C onte nts 3 editor.publisher Wayne Green W2NSD de W2NSD, Editorial 4 publication s manager David Fish New Products _ 35, 50 e ssoclete editor Jim Kyle KSJKX/b letters to Editor 49, 57, 61 associate editor _ Don Smith W3UZN E:ttremely Importa nt Notice 58 MA RS Technice] Net Broedcests 55 e ssoclete editor .. " ' " Marvin Lipton VE3DQX Other He m Publlceticns 63 soles representetive Jim Morrissett WAbEXU Adve rt ising Inde x 62 subscription s see December cover Cut Out and Send In O uestion noire 50 fre nsportetlon Persehe COVER: W2M UM 's Mosley beam as photoqrephed by Joe Schimmel W2Q DM .

,3 ) [aK~7.J lI e Is puultehed monthly lJy ,\ ll1 all'ur lh d lo l'ulJ IIshlnll. Int'. • 116 )Ialn Htn'l't. :\"orw aIk, Conneetlcut. Buslness Offi ce , 1379 l':ast l :ilh S tr....t . B rookI)'n :lO. xew York. T elephone : I:\" g ersoll !H l!I;J 7. SulJscripllon r atee : U. S. A. and pOli N I JOnl , APO. }<'I'O, C.nada and )lu Iro; one )'ear $3.00 ; two )'ea~ $5.00; urree yean $7.00. l" orelllll: 0111' year $4.00 ; two )'ean $7.00. Application fQl" ent ry II s....<{lnd ·cJ.1I matter II po>n dIll1I at :-i or.ulk, (' OIl Il ~t1 ('U t. Prtnted III Ihe U.S.A. E nUre con to>nll co p)'rlllht 1961 by Amateur R ad io Publbblnll, l ac. l'oJit masler: P ielaI' lend fQl"m 3579 to 73 )lIl( lZlne, 1379 E alt 151h Street, Uroolll)'n 30, :\"e~ York.

JANUARY 1961 73 MAGAZINE • 3 •

stble advertiser for some infonnation and you could suggest that you'd like to see him sup­ ••• de W2NSD porting 73. ) Iost important of all are the advertisers who are presently supporting 73. They should (Never Say Die) be made rich and fat as a lesson to others. They will be very contented if you drop them a card a sking for further information about E'RE st ill completely embroiled in the their products. Before you shrug off the re­ W mechanics of sta ying alive, worrying in s ponsibilit y of this you should consider whether turn about subscriptions, articles, advertisers, you like 73, whether you like the basic ideas printing the next issue and (gulp) paying our which it represents, and if you think they bills. T here are a few unavoidable diversions are important enough you should take the such a s a chap who wanted us to help him get time to hel p a bit. Please r emember t hat an FL8 license (he got it). a chap go ing to though Br and X ha s five times our circulat ion Zanzibar and wanted some gear (he got it), the advertisers expect t he same results . .. going to conventions (Miami on J an uary 14th, which means that the intrepid band of 73-ites P hoenix in May, etc.) , talking to local clubs, has to be five times as active just to b reak fighting the flu (and losing), and trying to even.Rally to the post cards, men. beat down a growing mountain of mail with my recalcitrant typewriter. Fearless Survey Helping Hands Looking through the December issues A f ew fellows have really gone all out to of some of the more prominent ham let people know about 73 and to try to get magazines we find that the number of everyone they knew or worked to subscribe. pages devoted to technical and construe­ One of the most energetic is Ralph Morris, tion articles runs about like this: ' VI QU E of New Bedford, Massachusetts. 73 Magazine 33 pages Ralph sent in list after list of subscr ibers and Brand X 28 pages put up his own money for the subscriptions, Bra nd Y 23 pages collecting it later from the other chaps. Another bundle of energy is Don Smith, W3UZN, our Associate Editor down in Hag er st own, Maryla nd. There are many others Pacifists that ha ve helped tremendously too.Believe me we appreciate it and possibly might have Magazine reading is a pretty passive pas­ not been able to get the magazine properly time and I suppose this ha s a lot to do with started without it. the t remendous inertia that I sense every time If you are more interested in 73 and seeing it I suggest "doing" something. Like getting you grow than perhaps just reading it over every to pepper the advertisers with encouragement month and then forgetting about it, then you or cast a monthly vote for the articles you like can help. You can show it to your club mem­ best. bers and talk them into subscribing. You can How about taking an active interest? There discuss our articles over the air and pass along are lots of things you can do. w hen you find our address to the interested. Maybe you'd a ham parts di stributor that does not have like a sa mple copy sent to someone... just any copies of 73 on the counter you could tell send us the name and address (we're printing him about the magazine, suggest he order a few extra these days for this) . Perhaps you some counter copies, or drop me a card with know one of the manufacturers who should be his name and address so I can hound him about advertising in 73 and can pass a long some it. If you forget the address of t he magazine enthusiasm. You might be writing to a pos- just look up \V2NS D in a ny Callbook. Per haps you know of some company t hat i:m 111l 1111l1111l1111l1111l1 111l1111l1 111l1 111l1111 1111l 11 111 111l1 111l1 111l1 111l1 111l1 111I1 111II 111I1 111 11 111 11I 11 1lliiii"1II 111 11 111 11 111 11 11111 111 11 IIIU< would do well to advertise in 73. If they have been advertising in othe r ham m ag azines you : Old Call Books may be su re t hat I a m after t hem . .. if not , Few DX operato rs ce n efford to buy a C"II - = t hen drop me a card with thei r name so I book. If you have one tbet is less than three -­ can send them information. veers old that you would like to send to e OX Now t ha t home-brewing has dropped off to he m then d rop " card to Cliff Evans K6BX e nd he will send you a letter from e OX a shadow of its previous self we see few ads h"m that would like to heve your Cellbook. from component manufacturers. For that K6BX. Box 385. Bonita . California. We think matter we see that many ham di stributors ~ this is a wonderful service and extend our best = have just about dropped their parts depart­ req erd s to C liff for his work. ment. I hope that we can change the tide on ~ • this and revive a ~~weeping interest in home

4 • 13 M AG AZINE JANUARY 1961 THE MULTIPHASE MODEL MM.2 RFANALYZER

• Monitors the RECEIVED and TRANSMITTED s Ignals . Shows flat -topping, over modulation, parasitic s. keyed wave shape etc. Silent e lectronic switching keyed by transmitted RF . • No tuning required , Broadband response flat 1 MC to 55 MC at power levels of 5 watts to 5 KYV. • New va riable sweep control for trans mit and receive. • RF allenuator controls height of patt ern. Calibrated in 3 DB steps. • Function selector for ENVELOPE, TRAPEZOID and BOW ~ TIE patterns on transmit. For SSB, DSB, AM and CW . • Built-in 1 KC audio osc illator , le s s than 0.5%distortion. With 3" scope, is ideal for complete alignment of SSB exciter s . • For usc in se ries with 52-72 ohm coax line s . A short pickup antenna may be us ed with other systems. • Plug-in adaptors available to match 50 KC , 60 KC , 80 KC or 455 KC r eceiver IF systems. Only one simple connection to receiver. h.!M- 2 Kit (less IF adaptor ). $119. 50 T HE RE IS NO SUBSTITUT E FORASCOPE IF YOU WANT Wired (less IF adaptor) . $149. 50 T HE C LEANEST, MOST PERFECTLY MODULATED Plug-in IF adaptors (wired only) . SIGNAL YOUR TRANSMITTER CAN PROVIDE. THE MM-2 RM-50 (50 KCI. RM-80 (60-80 KC). ISBY FARTHE MOST DEPENDA BLE and EASIEST TO RM-455 (450 -500 KC). .. ea . . . $ 12.50 USE. SINC E IT WAS DESIGNED ST RICTLY FOR TRIS PURPOSE .

ENVELOPE R F TRAPEZOID

[J MM -2 AM TOKE SSB TONE LINEAR FLAT TOPPING

o , o R~ ~ 'l'IKC IKC RF RF SSD·AM AM VOICE SSB VOICE RF OUT IN EXCTR.0VER BIAS PARASITICS

A F TRAPEZOI D A M TRAPEZOID f7

MM-2 AM MM- 2 AM 100% OVER MOD . 100% 75% , o , o

IKC RF AF IKC RFA F LO-LEVE L MOD. AM 75% NON-LINEAR RI-LEVEL MOD. REGEN. OVER MOD.

OTHER FINE C.E. PRODUCTS Model 600L Broad -Band Linear Amplifier $495.00 •Model 20A Bandswitching SSB Exciter $299. 50 •Model lOB Multiband SSB Excit er $193. 50 •Model GC-l Gated-Compression Amplifier...... $ 66.50 •Model B Sideband Slicer with Q Multiplier $104.50 • Als o avail able in kit form AND MANY OTHERS.,. WRITE FOR LITERA TURE THE SSB PIONEER

JANUARY 1961 73 MAGAZINE • 5 construction. Whoops, there I go dreaming again. Why do I always try to make t he world over the way I want it, including stiff battles

, : i with City Hall. If I had a ny brains I'd see t hat old handwriting on the wall and print what '1 everybody wants : a magazine full of tests of commercial equipment which tell you how STRENGTH great each item is. Get away from me with t hat straight-jacket.

Which Do You Li ke Best? o The votes are in for the November issue and z THREE REASONS WHY again we find t hat every article in the book YOUR BEST BUY IS ... received some first place votes (by other than their authors). The winner t his month is Tom Sowers W3BUL and his Transistorized 10 Meter Converter. A check has been sent as t he winning prize.In second place by only a I couple of votes was Jim Kyle K5JKX/6 with I­ his $5 Frequency Counter. Our technical ar­ E·Z WAY AERO-DYNAMIC ticle for t he month on noise limiters placed ... d e sign d ecrea s e s wi nd load t hird. Tied for fourth place were Bill H a mlin and. pr ov ide-s tele s c o ping WIMCA's Improving the Performance of the action that permit , ' rai s in g , and lowering of t ower sections . Gonset III and John Wonsowicz W9DUT's , CRANK UP TO 60 FEET. VHF Tri-Mode Receiver. DOWN TO 2S FEET and them to be of inter est. Five articles will do. TILTS OVER FOR ACCESS The winning author gets extra pay, see '? TO ROTOR OR BEAM. " ;~ l­ TRENGTH b u il t · in to every E·Z Wo.f T ow er . ••He a v y e:( w tl! 1 steel t'U bing legs, c on. ALetter From Mama ti nl,lou s d i, gona l br a c in g o f so l~ Char lie Weaver (Cliff Arkett), frequently s:tee f rod a nd e le ctr ic. seen on t he J ack Paar television show, was ee II)" we ! ~ e d thro ug hout.. .. no lo os e bo1ts or nuts here. E-Z active on ten meter phone in t he late 1930's :e Way sig n ond s t reng th a re as W6SGP (Sweet Grand P a l , engaging in e:( your Oss urance of DEPEND­ long QSO's in the high, quavering voice of ABILITY that you can cou nt an old man. • . .WflH[(F 1&1 on year a fter yea r. See your lIl:I ne are st d is tr ib utor t oda y or w rite fo r free literature. Long Live 50 Cycles Much electr ical equipment, including ama­ Q Th e SATELlITE teur communication gear appears on the Model R BX ·6 0-3~ (Po inted) $335 .00 market today still bearing the notation "for Z Mode l RBX·60·3G (Ga lvo ni::ted) $410.00 50-60 cycles" despite the fact t hat the last e:( MOUNTING KITS, part of t he country of any consequence having lIl:I G~K X60·3 (Grou nd Post) 5125.00 50 cycle ac was the Boulder Dam area, includ­ BA KX (W a ll Broc ket) $17.00 ing Southern California. Through 1941 many - W6 CW stations could be identifi ed by t he Freight Prepa id a nywhere in (48) U.S.A. peculiar buzz on their notes resulting from t he lower efficiency of t heir power supply fi lter s at that f requency. The 50 cycle st uff did serve admirably as a standa r d reference for calibrating audio oscillators and frequency standards. . ..WflH[(F

Lowering C rystals If you're looking for different ways to lower t he frequency of a crysta l try sodium silica te, sometimes known as 'liqu id glass.' Available in drugstores and hardwa re stor es at very small cost, successive coats can be brushed on or washed off as the case demands. P.O. BOX 5767 • TAMPA 5, FLORIDA •. .WflH[(F

6 • 73 MAGAZINE JANUARY 1961 Mailthe FREEl LAFAYETTE coupon 324-PAGE 1961 CATALOG today America's "Electronics Shopping Center" for your SATISfACTION GUARANTEED OR MONEY REfUNDED fREE copy EASY PAY PlAN-the slmplest, and quickest way to get what you want when you want it As little as $2 down .•• up to 24 months to pay. NEW! LAFAYETTE HE-20 DELUXE CITIZENS BAND TRANSCEIVER

- o Built·in 12 Volt P.wer Supply 99050 o 14 Tube Performance $5.00 OOWN o 4 Crystal·C.ntrolied Transmit Positi.ns plus 4 Crystal·C.ntrolied Receive Positions HE·20WX o Tuneable Receiver over all 23 Channels Completely Wired

NEW! LAFAYETTE HE-2S"VOYAGER" LAFAYEITE PROFESSIONAL QUALITY COMMUNICATIONS RECEIVER­ 6 TO 80 METER TRANSMITTER ENGINEEREO FOR THE AMATEUR A Sensational Value Jar Your Ham Shack

Completely KT·200WX Wired HE-25WX in Kit Form 64.50 109.50 5.00 Down Imported 5.00 Down •••• • Superhet Circuit Util~ing 8 Tubes and HE·l0WX Rectifier Tube Wired IMPORTED • Built.in "S" Meter with Adjustment • Single Knob Bandswitching-110 Through 6 Meters Control and Tested • Full 120 Watts CW, 70 Watts Phone • Full Coverage 80·10 Meters 79.95 • High Q Pi Network Output Circuit Matches Anten· • Covers 455kc t. 31 mc 5.00 Down nas From 40-600 Ohms • Filtered and Shielded for TVI Suppression • Variable BFO and RF 6ain Controls • Clean Keying-Minimum of Clicks or Chirps • Swnchabl. AVC and Automatic H.ise Limiter The perfect Transmitter for Novice, Technician or The Communications Receiver that meets every General. Completely self contained with efficient amateur need _ available in easy-to-assemble kit Class C Final amplifier operation on all bands. form or factory wired and tested. Sign-al to noise Tubes: 6AU6 crystal oscillator. 6DQ6A multiplier- ratio is 10 db at 3.5 MC with 1.25 microvolt signal. buffer, 2~DQ6A final amplifier beam tetrodes, l2I\X7 dual triode audio amplifier and a 6AQ5 clamp Selectivity is -60 db at lOke, image reflection is tube modulator. Shpg. wi.• 38 Ibs. -40 db at 3 MC. 7'-0".15".9". Shpg. wi.• 22 Ibs. • ~.A.:Y"ETTE 165-08 LIBERTY AVIHUE, JAMAICA 33. H. Y. oft B. .A. :J:> X 0 011lEl LOCAT~'S ---- HEW YORK, H. Y.I HEWARK, H. J. I BRoHX, H. Y. IPARAMUS. H. J'1 BOSTON. MAss. I PLAIHflD.O, H. J. 100 6th Avenue 24 Central Avenue 542 E. Fordham Rd. 182 Route 17 110 Federal Street 139 W. 2nd Street ------~------"l""!!:;;;. I lafayette Radio Dept 73A·l P.O. Box 190 Jamaica 31, N. Y. FREE 324-Page: 0 $ Enclosed. Send Stock # ...... 0 Rush FREE 324 Page Catalog 61D 1961 I 0 $ Down Payment Enclosed for Stock # . Catalog No. 610! Lafayette Easy Pay Application Will Be Forwarded Upon Receipt of Down Payment

I Him. _ Cut Out & Paste I Addt... on Post Card ~ i Cltl Zone Stlt• • • -- .._ ---

JANUARY 1961 73 MAGAZINE 0 7 -

Nuvistor Converters for Six & Two

Tom l omb K8ERV T HE recent article on Nuvistors by Tilton' 1066 La rchwood Rood has created a great deal of excitement on Mansfi eld. Ohio the two meter band.\Vithin a month of pub­ lication there were at least five low-noise Nu­ vtstor preamps on 2 in Ohio, with their owners giving glowing reports of performance. A small group" of Ohio amateurs interested in low-noise conversion recently met to check the performance of the 6C\V4 Nuv istor on 144 me. This group used three noise generators and three receivers ( HQ- l lO, 75A-4, 2A) to check several 60\V4. 417-A. and commercial converters. The result was that the 6C\ V4 is as good, or slightly better than, the very best 4 17-A '5, and is a considerably easier tube to use.

1. Tilton, " T he Nuvtetoe as an rf Amplifier at 1440 me;' Q ST, September. 1960, p. 38. 2. Those attending : WgSFG, W 8LCA, W 8WNM, W 8QVK, K 8Mf'Z. K 8ERV.

8 • 73 MAGAZINE JANUARY 1961 (Here are a pair of compact converters that will give Meteor Scatter performance without hanging a mortgage on the roof. The heart of the circui t is a new tube desi gned for VH F service.)

PARTS LIST COIL TABLE L 1- 5+ # 26 en em el on '/4" polysty rene form , wi nd c r. C2, C S, CI I, e 12, Cl 4-500mm fd ceramic ( Erie ebcut %" long. Tep 2t from grou nd e nd. Adi ust G P- SOO) by apreedinq t urns. c s. C 6. C7. C IO. c u. C IS, C16, Cl9-1000mmfd L 2-Ne utrll lizina coil. About 20t # 30 on 5/32" d ill . si lve r-mice buttons (Erie FA - IOaO) high velue resistor.C lose wound . Adjust by C 4-lmmfd o r twisted wire spreedinq turns. ca, C9, CI7-1 -5mmfd tubulM trimmer (Surpl us- L 3-Some es 1I but no top. Borry # GC-35, IO¢) L 4-lt li n~ ove r L3. C l8-12mmfd NPO ceremic [Centeeleb Tel-121 L 5-6t top lit 2t, otherwise es 1I. C20. C2 1, e 22, C23-IOOOmmfd disc ce ra mic L b-26t # 32 enamel on II", " slug t uned form. close C2 4 'l 0mfd 250 volt electrolytic wou nd. {CTC PLSb form with green slug} C25, C2b-20m fd 250 vol t electrolytic L 7-2t lin ]; ove r Lb. L B-51/2t # 24 enemel close wound on C 8. RI. RS- 47k Ij,w L 9-1 9t # 32 e nem el close wound on C9. R2 , R6-220k 'j,w LlD-16t # 28 en amel top 51/2t fr om grou nd. Slime Rl , R7-100k 'j,w form <'I S L6. R4, R8-470 'lhw Ltl -c-N e ut relhinq coil. About SOt # 36 e ne mel wound R 9-500 2w <'I S L2 . RID-3k lOw (depends on TI) L12- 19t #28 enemel on Slime form es Lb. RI I- IOO I w L1l-1 t l in~ ove; 1I 2. R12 , RI3- IOk 2w (depends on Ti l L1 4-lt l in~ ove r LIS. VI . V4--6CW4 RCANuvistor (Socket C inch-Jones) 1I 5--17t <'IS L12. 133 -65-10-001) II b-SlIme es Lb. V2, vs, V5, V6-6AKS L1 7- Some es L7. V7-QB2 LI B-25t # 32 on sli me form es Lb. 51, S2-DPST toggle switch 1I9-2t li n ~ over LIB. DI-Silicon Diode, 600 PI V [Iexes Instrument 2071) Note: In ple ce of Silver-Mice button conde nse rs, TI -See Text whic h li re rether expensive. .001 discs moun ted with XI - Third overtone crvstel. 38.66666 me short leeds on 1I stand-off lug con be used will wo rk X2-Third overtone crystal, 22 me just es well.

vr vz 6CW4 6Ak5 6Ak5" " 28-501llC , i OUTPUT , • t.e "<11K • '" Ei to """" cs •• ~ ." '" T IOOO .-;r '-.-' ~ • • c

ve ve 6CW4" 6AK5 1';" 6Ak5 TO Iol lkER

U'3QIolC , e wtrl 5.O-52 "C • I• OUTPUT I • --- • '"'-'!I" '" n"" eq ~ -'- " '" " " "'~ '' ~ to ~ "'" ...--. no" CI5 '"1000 - - T ~o T 000 - ~ ~ -r~ ~ ~ .- -e- , TO OSCILLATOR , c ~

JANUARY 1961 73 M AGAZINE • 9 started backwards, with the oscillator-multi­ plier first. The if

A 28-30 me if was chosen for the two me coverage found on most In-meter receivers. The high intermediate frequency eliminates all image problems, and allows a simple broad­ band output coil to replace the usual cathode follower matching stage.

The O scill ator The lower transconductance of the 6CW4 (12500 umhos vs 25000 umhos for the 417-A) A 38l; me third overtone crystal oscillates makes it more stable, with a small sacrifice in a conventional turn ed plate circuit, using in gain. \Vhile a high transconductance is the 6AK5 screen as a triode plate. The plate usually thought to be essential in a low noise circuit triples to 116 me. This very simple tube, actually it is the ratio of transcon­ circuit generates a stable signal and sufficient ductance to plate current (among other mixer injection with a low tube dissipation things) that determines the noise figure of a tube. The very low plate current of the Nu­ vistor gives it a slight edge on the 417-A in the GmjIp ratio. The 6CW4 is probably the best tube presently available for stable, low noise amplification in a grounded cathode cir­ cuit. It is a thimble-sized, budget-priced paragon. The group's very careful measurements gave the 6CW4 converters a noise figure of 3.2 ± .4 db. This is not a startling value when com­ pared with the claims of so me of the 417-A jobs. However, the accurate measurement of noise is difficult at best and can be very easily and a B+ of only 105 volts. Initial adiust­ (and unknowingly) "helped out" several db ment: tune C9 for maximum negative grid VTV~I by improper measuring techniques. A true voltage as indicated hy a at pin 1 of figure of 3 db is quite good and is probably V3. The plate circuit will be tuned later. exceeded only by the exotic 416-B. The Mixer The mixer stage is conventional. A triode connected 6AK5 with grid leak bias gives low noise mixing in a simple circuit. The output coil is self-resonant for broad-band coupling into the receiver. If a full 4 me bandpass is required, it may be necessary to load L6 with a resistor or by increasing the turns on L7. Capacity coupling from the oscillator develops about two volts of bias. Adjustment: Dis­ connect the B+ lead from the 6CW4 at point X, and connect a 28 me receiver to the con­ verter. With a VTV~I on the mixer grid Converter Desig n (pin 1 of V2), adjust C8 for maximum nega­ tive voltage. This should ru n about two volts, The converters were designed for low noise. but isn't too critical. Now adjust L6 for maxi­ compactness, and low cos t. While the 6CW4 mum receiver noise, being sure you don't tune could be used throughout, the lower cost to the receiver's image frequency. If the re­ (surplus) 6AK5 serves just as well in the ceiver isn't sensitive enough to pick up mixer mixer and oscillator sections. The design was noise, L6 can be tuned later.

10 • 73 MAGAZINE JANUARY 1961 The rf stage is a "steal" from the KllJB If a noise generator is available, the input design. For all Ye Doubters, it can be shown tap and Ll tuning can be further improved, both mathematically and by experiment that but a 4 db noise figure was obtained with the a single rf stage with a gain of 20 db or above procedure. better is suffi cient to swamp out the noise of even a moderately good mixer stage. Addi­ Th e 6-Meter Section tional rf stages may in crease the converter gain and bandwidth, but will not noticeably The six-meter converter started out with improve the noise fi gure, and may lead to the circuit of the first two stages identical to overload problems. Any needed gain should the two-meter unit. The triode mixer immedi­ be placed ahead of the receiver, not the con­ ately developed a few bugs. First, it was verter. Wlth anything less than a 2-meter difficult to obtain enough injection coupling lew in your block, th e single rf stage should a 22 me signal into a 50 me tuned circuit. not produce cross-modulation in the converter. Cathode injection was tried with excellent re­ The rf stage from LI through L4 may be sults. Next, the mixer oscillated when L16 built as a separa te preamp for an existing was tuned to 29 me. Apparently the broadly converter. Several have been built with close tuned grid and plate coils caused some feed­ duplication of coils and performance. back at a common frequency. Changing to a pentode mixer solved this problem. The over­ Adjustment all noise fi gure on six is 3 db, so the pentode connection does not contribute too much noise \Vith all previous adjustments roughed in, at this frequency. the rf stage is ready for alignment. With the The adjustments and operation of the six BCW4 B+ still off, connect an antenna and and two meter converters arc identical. One receiver to the converter and tune in a strong caution-be sure to use iron slugs in the six­ local signal. (A GOO may not work due to meter coils that are intended for use at high direct pick up in L3 or 1.5.) Roughly peak frequencies. The Cambridge Thermionic L3, 1.5, and LB. Now carefully spread L2 for green and white slugs are rated for use in a minimum received signal. The neutraliza­ the 50 me range. tion point will be a sharp and almost com- • Th e Common Power Supply

The power supply is conventional and will be described only briefly. The requirements "'" of each converter are 60-70 volts at 10 rna for the rf and mixer stages, and 105 volts at 5 rna for the oscillator. The VR tube should be set to draw an additional 15 rna, for a total of 30 rna. A TV booster type of sup­ ply will power one converter, especially if the V B tube is omitted. For operating both con­ verters at the same time a larger transformer is needed. plete null. A few turns may have to be (Continued on page 50) changed, but in all cases neutralization has been reached very quickly and easily. Now reconnect the B+ lead and tu ne in a weak signal near the center of the desired tun­ ing range. Peak L3, L5 and LB. Ll will tune so broadly th at it may not seem to be effected by adjustment. Itechcck the neutralization and secure L2 with Q dope. As a final stabil­ ity test, insert an 0 -10 ma meter at X. The 6C\ V4 current should run close to 8 ma and should not drop when the antenna is dis­ connected at th e converter jack. Any drop indicates oscillation of the rf stage.

JANUARY 19b1 73 MAGAZINE • II Down

With Drift!

Jim Kyle KSJ KX/b

These graphs show before-and-after performance of a BC-779 (Vintage Super-Pro) which was modified as explained in the text. Note th at prior to modification, drift was measured in kil ocycles, while after, overall drift was less than 50 cycles.

H ow's the stability of your receiver? Does Convinced? Ready to go out and trade off it stay rock-like and steady where you the old rig for a new super-stable receiver at tune it, or does it have a tendency to wobble a cost of half a kilobuck? Relax-you don't and drift, thus necessitating retuning every have to. Here are seven gimmicks to improve few minutes for the first hour or so that you're the stabilit y of any existing receiver. Any of on the air? them can be used alone, or all can be combined. Chances are. unless you have a recent model Naturally, the more you use the more improve­ of receiver-and one of the t op-price models ment you'll get-but don't jump off the deep at that-that the rig could use some improve­ end too soon. Just three of them managed to ment in the sta bili ty department. tame a drifting Super-Pro down to an overall And if you s hould chance to a sk. "Why 40 cycles in the fir st hour! bother? I ca n retune u ntil it warms up," here T he first two tricks involve no circuit are three good r easons for making that im­ cha nges in the receiver, so you might like to provement: try them at the start. In the first place, it's much more convenient Number One is an old ie. Since most frequen­ to be able to tune once and sta y there than it is cy drift is ca used by heat trapped in the re­ to be conti nually touching up the adjustment. ceiver circuits, added ventilation will reduce Secondly, if )rou intend to utilize ultra-selec­ t he heat and therefore will also reduce the tive receiving techniques such as crystal fil­ drift. The simplest method of getting more ters, Q-multipliers, low-frequency if adapters, ventilation is simply to open the lid of the re­ or audio filters, frequency sta bilit y is a must. ceiver cabinet! The super-selective gadgets are a distinct Pur ists may not like t he appearance of a hindrance if the received signa l is wandering receiver sitting in the shack, its cabinet lid over the dial, even though they are a great open. They can place a sma ll blower on the help when the signa l sta ys put. side or rear of the cabinet to achieve the same Finally, in case you're interested in side­ r esult at a much greater cost. band, you will find that signals must at a y put Trick Number Two isn't so basic or so ele­ to be readable. Just 50 cycles drift when list­ mentary, but it can be a great help in taming ening to a sideba nd sta tion will make the voice an olde r Driftmaster. sound unnatural, and very much more than In most of the better-class r eceivers, there this will make it unreadable. is a centering-adjustment scr ew on the tuning

12 • 73 MAGAZINE JANUARY 1961 capacitor rotor sha ft. This screw adjusts pres­ put problem by trying to eliminate or mini­ sure at the sha ft's rear bearing. mize t he effects of heat. Now, we're making Pr oper adjustment of this screw will result a t urnabout. \Ve'r e going t o use t hem. in decidedly-lower drift. The object of the ad­ Of course, it's not quite a complete turn­ just ment is to get the ca pacitor r otor plate. a bout, since we're going to be using them t o in t he exact center of t heir area between the counter act ot her heat effects. stator plates. Expansi on of t he plates {cause-" \Vha t we're going to do it this: Install tem­ by heat) will then have a much smaller effect perature-compensating ca pacitors a t st ra teg ic on frequency of the local oscilla tor , since t he points in the oscillator circuit to make heat di stance from rotor t o stator plate will be at effects cancel out a s much a s possible. its greatest. Since ever y receiver reacts to heat differ­ To make t he adjustment, t une t he receiver ently, no ha r d-a nd-fa st formula can be given to a stea dy ca rr ier of known stable frequency to help you find those st r a teg ic spots. A good (such a s a broadcast st a t ion or \VWV). Tur n place to st a r t is right at t he t uning ca pacitor on t he B FO and adjust for comfortable pitch. f r a me. U se type N75D capacitor s, and don't Now, without touching the tuning knob or add more than 5 micromicrofarads if you can BFO adjustment, adjust the sc rew for t he low­ keep from it. In other words, if 5 mmfd doesn't est beat note. T hat's all there is to it. do the trick, look for another place to put the The other five gimmicks all r equire som e cir­ ca pacitor . cuit modifications in the set ; finish r eading the Naturally, t he capacitor's electrical con nec­ a r t icle, t hen heat up the old soldering iron a nd ticn will always be t he same-in parallel with prepare to dig beneath the chassis. t he oscillator section of t he ma in t uning gang. Number Three is also based on the heat-drift Only its physi cal location may d iffer. relationship and applies on ly to older sets Closely allied t o N umber Five is Number which use metal or g lass-octa l tubes. Six.However , it uses no special component These large tubes have large elements, a nd such a s t he t emp-compensating capacitor. It is a re t hemselves a heat source. The large tube t his : elements expand and change position a s the Disconnect the leads from the ca t hode termi­ ca t hode heat s. This expansion result s in fre­ nal of the oscill a tor t ube. Then, between the quency drift when t he t ube involved happens cathode and an y or all leads which were at the to be the oscill a tor . socket terminal, connect a 1,80D-ohm composi­ The remedy is this : replace t hat big bottle tion resistor. with a m iniature t ube. The 6C4 is r ecommend­ ed as a r eplacement for an y triode, triode-con­ nected pentode, or st ra pped-g rid converter • .. tube such a s t he 6SA7 when used in the oscil­ • la tor st age of a r eceiver. Except for chang ing l:i K 2200 the socket, no circuit modificat ions are neces­ .r . !nO' sa r y since all r eceivers oper a te this tube at w ra t ings sa t isf a ctory for t he 6C4. l.Ir-r . 12 AT7IS£ E TEXlI The small elements of t he 6C4 st ill cha nge 0 posit ion with heat, but t he a mount of change ------MIX ER is smaller and so is the resulting signal drift. 11'I10 T rick Number F our is really a switch on TOOL[; ~ CIRClH T • Number Three, but is highly recommended f or 1M ~IOO both old and new sets si nce it combines all the 2200 • • sma ll-tube advantages w ith the additional 100 bonus of a buffer sta ge. Number Four is the t win-triode cathode­ •• cou pled oscillator. First described some two years ago by Leonard Geisl er (who used a t ype Fig. I- This circuit, substituted for your re­ 6SL7 and thus m issed some advantages), this ceiver's present oscillator shge, will substen­ circuit may be subst it uted for the oscillator tia ll y red uce fr equency d rift. Parts val ues a re st age of almost any communication s r eceiver . non-critical, but lead d ress must be direct li nd \Vir in g of t he st age is shown in F ig. 1. N one short. Use of a Vector 6-N-6T socket or an of t he parts values is particularly critical, but Amphenol t yp e 59-369 socke t will simplify wi r­ make sure that all leads are a s shor t a s pos­ ing and installation of the stage. sible and that all bypass capacitors are secure­ ly grounded. The reasoning behind this gimmick is some­ If you don't happen to have a 12AT7 around, what involved technically. Researchers at use a 12AX7, a 12AU7, or with modification RCA Laboratories di scovered it while investi­ of the heater connections, any of the cascode­ gating stabilit y of TV oscillators in the UHF type TV twin triodes. They all work nicely. r egion. They r eport t hat changes in "cathode Number F ive d iffers from all its forerun­ interface resistance" occur when su pply vol- ners. So far, we've been approaching the stay- (Continued on page 61 )

JANUA RY 19b1 73 MAGAZINE • 13 .. .t t •• • •

Combining Kits for 100 Watts on 6 & 2

H ow does a 100 watt G and 2 meter, crystal DOMld A. Smith W3UZN controlled transmitter complete with Associete Editor power supply and plate modulator for $200.00 sound to you? Good, eh? Using kit equipment manufactured by E. F. Johnson, Heath Com­ ply voltages brought out to the VFO plug. pany and Eico, you can build such a rig. These It covers 6 & 2 meters and sells for $34.95 in three pieces of equipment go together as if kit form and 54.95 wired. The National Com­ they were made for one another. pany also makes a VFO for both bands which The transmitter section of the complete rig they call model VFO-62. It is available only is the Johnson Viking 6N2. It uses the pen­ in wired form and sells for $49.95. (This is tode half of a 6U8 tube as oscillator-doubler, a reduction of $20.00 as the unit originally the triode half as a tripler to 48-54 me. A sold for $69.95.) Another VFO is the Globe 6360 is used as a driver on 6 meters and a model 6-2, selling for 49.95 in kit form and tr-iplet- on 2, driving the final amplifier which 59.95 wired. I have used the Johnson and is a 5834 tube. The 5834 is an excellent choice National VFO's with the 6N2, both wi th ex­ for these two bands, running 100 watts input cellent results. AM on both 6 and 2. A 6AQ5 is used as a Your "Ca talog Searcher" found the perfect clamper to protect the final. Efficiency is very answer to the power supply problem in good on two meters (where losses are gener­ Heath's UT-l Utility Power Supply kit. The ally very high), du e to the use of silver plated supply is r ated at 600 volts at 250 mils. or tuned lines in the final The rig u ses the com­ 600 volts at 200 mils. and 300 volts at 100 mon 8-9 me crystals for both bands and has mtls., which is just what the rig requires! The provisions for the addition of an exter nal supply also furnishes 6.3 volts at 8 amperes VFO. An 8 prong female socket is mounted on for filaments. The circuit u sed in the supply the rear panel for this purpose and has fila­ is the well known voltage doubler with large ment and proper B· available from it. (This value input a nd output filter capacitors. Ex­ voltage comes from the supply furnishing vol­ tensive filtering is used in the primary of the tages to the rig.) The 8-9 me output from power transformer to reduce TV!. This filter­ the VFO is also connected to this socket. The ing includes two line chokes and four bypass Viking does not contain its own power supply capacitor s ! A neon lamp is mounted on the or modulator and requires 600 volts at 200 front panel to indicate when the supply is on mils., 300 volts at 70 mila., plus 6.3 vac at 3.5 and both sides of the ac line are fused with 3 amperes. 50 watts of a udio is necessary to ampere fuses. plate modulate the rig at 100 watts input. Catalog sea rching also turned up a 50 watt As mentioned above, the rig has provisions plate modulator kit manufactured by Eico for an external VFO. J ohnson makes a unit (model 730.) The modulator is conservatively especially for this purpose. It does not have rated and contains the following tube line up. a built-in power supply and requires the sup- An ECC83 (12AX7) is used as a two stage

14 • 73 l.4A6AZINE JANUARY 1961 speech amplifi er, a GAL5 as a speech clipper, a 6AN8 as amplifier-driver feeding two EL34 Sl-SPST TOGGl..E SWI TCH + power amplifiers in push-pull. An El\l84 tube (TRANSMIT SWITCH ) is used as an overmodulation indicator and , RI!IoDPDT 6.3 YAC RELAY , a slow warm up, heavy duty GZ34 is u sed for {POTTE R 1Io 8RUWUD • full wave rectification, eliminating the need for aKAIIAY·Il.S ,,'e, an external power supply for the modulator. , The modulator has sever al desirable fea­ " tures. One is the clipper circuit (6AL5). This is a series type clipping circuit with adjust­ ~ able clipping level. A filter is included in this NDTE:UP'PtR fl:E " CC*TACTS REMOY'"' 0 .... circuit to suppress high or der harmonics gen­ SEE TEXT. , er ated by the peak clipping. It is possible with this circuit to raise the speech level of the signal 8-12 db. Another feature is the out­ put transformer which is multi-tapped. pro­ viding a number of output impedances, one Fig. 2 of which is 3000 ohms, perfect for feeding supply when closed. F or safety this lead is re­ the final of the 6N2. The over modulation in­ moved from ground and the wire from the dicator indicates over modulation when the center tap of the plate transformer connected modulator out put signal exceeds the plate volt­ to pin 8 of the modulator output jack is also age of the rf amplifier. In this condtion, a disconnected. A lead is then run from this negative voltage will appear at the grid of the side of the switch to pin 8 of the output jack. indicator tube causing the indicator bars to A wire in the ca ble run from the modulator overlap. The front panel of the modulator con­ to the Heath supply permits the relay to con­ tains both gain and clipping level controls. trol the plate supply of the modulator. The old The Hea th power supply must be modified, plate switch of the modulator is now in series as it has only an off-on switch for ac power. and must be left to the on position. If cw is A 6.3 vac, DPDT Potter & Brumfield relay is desired, simply turn this switch to off and installed on the chassis of the supply in front the relay on the Heath supply will only apply of the large wire-wound resistor, as can be plate voltage to the rig and the modulator seen in the photo. ASPST toggle switch is wiII be inactive. (See drawings.) also installed on the front panel, next to the ac off-on switch. This switch wiII connect 6.3 vac to the field of the relay when on, thus acting as the transm itting switch. The nega­ tive ( B-), lead of the power supply is con­ nected to one of the movable contacts on t he relay.Both lower contacts are grounded. The B- from the modulator will also be connected to the relay (the othe r movable contact), so that when the r elay is energized both the \ power supply and modulator will be on. -

,..- -+ GHO-SMIELD IN lOIlTTfA CABLE ~ .. 6.3 FIL-BLACK LEAD r-: + M(lIX.LATED MY' RED LEAD Power supply showing relay installed and extra ~----+ LOWYOl.TAGE~ L EAD (transmit) switch. Note that a heavy ground str ap ('A to ¥.. inch), should be run from unit to unit and ~ :s , .. ':T"-_ then to a good ground. This will prevent any ,,~ , of the units from being "Hot" and will provide .. a common ground r eturn for all of the units. Operating the complete r ig is a real pleas­ ure. The 6N2 is provided with a "tune" switch, permitting tune up without the final being in oper a tion. This of course protects the final amplifier tube until there is drive available. Fig. I After tune up, the proper modulation can be obtained by reducing the clipping level to zero The modulator has an off-on switch for the and increasing the gain control until the in­ plate supply, located on the front panel of dicator shows the two bars overlapping slightly the unit. One side of this switch is ground so when talking into the mike in a normal tone. that the switch wiII ground the B- of the (Continued on page 59)

73 MAGAZINE • 15 JANUARY 1961 • 1296 Megacycles Bill Ashby K2TKN-AFA2TKN BOll 97. Pluckemin. N. J.

UHF television transmitting tubes look in­ terestin g:, but don't plan on results til you have seen the amount of rf output compared to the input! It is uppnrant that the 1200 to 1300 me region is th e dumping ground for odd resonances, sneak circuits, and resonant grid structures. 2.15 inches of metal or less from a low impedance point is infinity-sand you can­ not get rf from one point to the other. I have IlCA-BIB!'s and IlCA 6181 's operating on 1296 me, but not at full power, or in circuits that an amateur would care to build. Both have good possibilities and can be obtained b y trading your grandmother, for they are used in UHF television transmitters. The 2C39A is excellent, so are other planar triodes that have W O HK on equipment for 1::>96 me started the grid structure straight across the grid ring. here four years ago. It was im mediately Grounded grid operation is a necessity, and apparent th at years of experience on 432 me stage gain is very low. Figure on at least four were not going to help much. Those circuits stages of triodes to get from the 10 watts out­ and techniques that had been found to work put from a 3C39A doubler to the 300 watts of well on 432 me would opera te, but the effi ­ rf necessary to drive a K\V input final! 2C39's ciency on 1296 me was terrible. There is as need air, plenty of it, not only on the plate, much difference between 432 me and 1296 me but the glass to metal seals must he cooled , if as between the BC band an d two meters! reasonable life is to be expected. I have four 2C39A's in parallel in a barrel structure that For Instance will take 500 wa tts input and better than 30% efficiency. The blowers and cooling system are Link coupling from one resonate circuit to four times the siz- of the rf section. another will result in at least 3 db loss. The tremendous advantage of 1296 me over Solid dielectric co-ax of any type. size, or any other frequency known is the possibility cost is useless. Eliminate all plans to use any of hearing weak signals. The noise out put of a amount, even a few inches for a flexible. good amateur-built receiver on 1296 me will twister section to the antenna or receiver. The d rop more than 15db when switched from a losses at 1296 me are horrible, and even a few good 52 ohm resistor load at room temperature watts will melt the line. Many have thought to an antenna looking at a cold portion of outer that with RG-17 or 19 and a short run, that space. This means you can hear a signal that they could keep their losses to about 2db­ is more than 20db weaker than you can on 432 actual practice shows that true loss is about 3 m e. Cosmic noise is low here, and amateur­ times published fi gures, plus 3db of coupling built paramps can be made to work. Aft er loss. They end up with well over 6db loss ill many hundreds of hours, acres of Hashing cop­ transmission-less th an ~ of th e very hard to per, and weak eyes from re-reading every get watts from the Xmtr get into the antenna­ available article written on paramps, I am cer­ and 6dh of loss in receiving is a disaster. "G" tain I know less now than ever about these line makes sense, but the lowest loss method is machines of Mephistopheles. Don't even to mount all 1296 me equipment at the feed ­ bother trying a 2K25 etc., Klystron for 3 ern point of the antenna. Use of 3" x 6" copper pumping at 129B. At least 300 milliwatts of clad down-spouting is a wave-guide possibil­ available power is needed from a 3 em pump. ity. 30 milliwatt klystrons work in well designed

16 • 73 MAGAZINE JANUARY 1961 paramps using a 3X Freq, pump, but the ex­ tremely important problem of keeping the pump signal out of the mixer circuit is in­ TRANSISTOR OSC1LLATOl't BUFfER , creased. A stable, controlled amplitude, pulsed 1.8148MC HAL f REO test signal on 1296 me is an absolute necessity 1.8148111C for test and tuning a parump! Dis-regard your

pet circuits-build a transistor crystal oscillator $AX:;- 6CU-6CL6- 6MiO 12 66 101

and the resultant 1266 me signal is the LO for 2C39-2C39 your pet mixer circuit. Couple the crystal mixer " '" thru a hi-filar coil tuned to 30 me directly across the cathode of a 6AN4 grounded grid 1266Me 1st if. and a reasonably stable, low noise 30 2.C39·~9 ,,,. IIIC SS B, me signal is available from the plate circuit of IiIIlKEIl-AW e...rrs orrwt the 6AN4. Usc of Vaructcrs for the last two multipliers in the LO allows use of transistors ",.., thruout the oscillator-multiplier string, with plenty of injection signal at 1266 me. "'SS.B.''' Antennas-be my guest! As a result of 4 - months of hard labor by K2Y UD, master • welder; K2HIA, welder - owner; \\r2"IHK, scrounger - deluxe; K 2TK~ , contributor of materials, elbow grease and design info; a 20 feet of chicken wire, and a wooden frame, ft. steel parabola, of welded cond uit tubing you will be in business. Yagis are impossible­ and covered with solid # 24 gauge sheet iron bed-spring and square corner arrays work, and takes up most of my back yard . It is still on a slotted sheet holds possibilities. the temporary mount, but by means of a 30 \ Vhen are you ready to start holding aurora foot tower and a winch it can be pointed at and moon sched ules? When pointing your an­ any interesting portion of the sky and with tenna array at the Sun gives at least 6db raise much labor can be tracked on the moon as in noise output from the tail-end of your re­ long as the beer holds out! \Vhen the weather ceiver and you can burn large brown spots on is bad and given about 2 feet of snow, work your fingers with rf off of the antenna feed may begin on the polar, motorized mounting. during Xmit. With Kraus handbook on antennas, 300 square (Continued on page 55)

Framework for 20-foot dish at K2TKN.

JANUARY 1961 73 MAGAZINE • 17 Operation

Berna rd D.Ross 394 t Eestwev Rood Cobiln Patrol South Euclid 18 , Ohio

E:-.IUEUS of the Cuyahoga County Ama­ garded as vulnerable; schools, a housing de­ M teur Radio Emergency Corps made velopment with 400 homes under construction, local news when they tcamed up with Olmsted shopping center, lumber company, and farm­ Falls police officers to put the damper on er's exchange. Not regarded as vulnerable malicious Halloweeners. Led by Police Chief and in need of no special attention on Hal­ Don Shirer (\ \'8QBF) , the combined forces loween or the several days preceding was the put three police cruisers and seven ham­ graveyard. "It's never been bothered," said equipped cars on the road to patrol specific the Chief. areas and to cruise the community. "A kid Last year a group of teen-agcrs set fi re to can't even spit out of a window tonight with­ kerosene-soaked corn shocks. Afterwards some­ out the police knowing about it," observed one armed with a fir e wrench opened a fire one high ranking city offi cial, a twinkle in hydrant, and by the time the police arrived his eye. to close one hydrant, had opened three more Hams served for the fift h year to augment elsewhere in town. An estimated 100,000 the police normally serving that and two gallons of water were lost to the community neighboring communities with a total popula­ that night. tion of 15,000. In the Olmsted Falls police station, the ama teur master control station was located in the same room as the police master control. This arrangement allowed the desk officer to hear amateur communications and to relay the information immediately to one of the police cars on tour duty. A police offi cer rod e in each amateur's car, ready to serve as legal authority if required. Special emphasis was placed on points re- Rudy to roll are (from left ) Walt Ermer, W8AEU. AI Dolgosh. K8 EUR , Ed. Schweikert, K8BUl. Ed Posey. K8KKO; (second row) Ahti Wahter, W8LHX. Art Cever. K8JHZ. Bo b Moc­ Leren, SWL, AI Holl ar. K8 DPA; (third rowl C huch J in o, W8NZI, Glenn Bodeker, KB SBZ, and Prentis Drew. KBSP L. Briefin g the force is O lm sted Falls Police Chief Don Shirer {WBO BF}. Front row, from left, are th e chief, Sergeant Harry Powers. Policewo man Mary Powers. and Captain Ferb Bowe n. In second row are Patrolmon l ee Wurstner. Bob Fenderbosch, Francis Anderer. and Lester Sellers. A chilly day and early rain seemed to dampen the normally rambunctious spirits on Halloween this year, although police had rea­ son to suspect trouble. Several sources re­ ported that teen-agers were planning to start a fi re, d rawing the nrc department and sev­ eral police cars to the scene. T heil they expected to have free reign through the center of town, The report indi-

IS • 7J MAGAZINE JANUARY 1961 ca ted the youngsters intended to break meters. Ahti is one of two amateurs who re­ windows of people they didn't like. destroy ports to the U. S. W eather Bureau for the signs, and possibly damage the city hall, thunderh ead net in time of threatened severe which houses both the fire and police de­ thunderstorms of tornados. partments. Another outsta nding ham in the patrol was Scouting around, a police sergeant found Ed Posey, K8KKO , renowned for his rescue what appeared to be a pile of brush and of ] 6 Valley View, Ohio, families in January debris, ready to he saturated with kerosene of 1959. Ed volunteered and piloted his boat and set a fi re. According to the report. the eq uipped with a 30-hp outboard motor to fire was sched uled to he started between 10 buck the current of the raging Cuyahoga and 11 P.~1. Fortunately, and for some un­ River. known reason, the rumored fir e and later The amateurs on "Goblin Patrol" found events never did materialize. much in the police group to appreciate and At a bridge repair site. youngs ters stole 34 admire. Mrs. Dorothv, Wurstner, wife of lanterns and more than 40 oil pots. Patrolman Lee \\'urstner. supplied and pre­ pared an urn of coffee and three frosted cakes each of the four nights of patrol for the coffee break. Each of the police offi cers seemed more genial than the next, the geniality chang­ ing to fi rm tone and manner when it came to cond ucting police work. During the coffee break on Halloween, when the cars had returned to the station, someone managed to place a kitchen stove in the middle of Olmsted Falls' main street. Could he have had a receiver? The 1960 Goblin Patrol ended at 12: 30 A . ~ 1. It had been a quiet and relatively un­ eventful Halloween. Parting remark of one amateur as he turned to Chief Shirer: "Thanks. Chief. Invite me to your party again next Thre e t een-a gers. obse rved from patrol car, year. 73 lounge casua lly in fron t of drugstore. a p pa re nt­ ly with out a care in t he wo rld. A few minutes e arlie r, police came up on barricaded roadwa y to trailer part leu than ha lf a b l o c ~ a way . sa w yo ungsters r u n ni n~ in d irection of dru3 store. Three IS-year old girls from a nearby com­ munity were apprehended with a ca ~ fu l of pumpkins taken from outdoor displays. The roadway to a large-scale trail er park was blocked off by pyramids of cinder blocks, topped by signs reading, "Speed Limit-IO MPH," and "Peddlers and Agents-Keep Out." Included in the patrol was Wnlter Ermer. \V8AE U. Edison Award wi nner in 1959 for his organiza tion and leadersh ip of the A HEC in Cuyahoga County. Said W nlt, "We all en­ joy it and the amateur acq uires a much better knowledge of what our law enforce­ ment officers contend with and vice versa.I think that only when the ham group is around on Halloween , do the offi cers have a really good time. \ Ve all have fun, and this type of activity helps train the amateur for the real emergencies when they arise." Ahti ("Ottie"') Wahter, W8LHX, operated Ahti W ahte r, W81HX, o pe ra tes his 6-meter the 6-meter master control OTI Halloween. On treseelv ee a ma te ur master co nt rol in the Olm­ preceding evenings, the patrol operated 0 11 10 sted Fall s Police Station.

JANUARY 1961 73 MAGAZINE • 19 Lost

In A Tunnel

Jim Kyle KSJKX/b 1851 Stenfcrd Ave. Santo Susene, Calif

Fig. I

OFthe many new devices introduced into the electronics world within the past few years, none has captured the fancy of engi­ neers, experimenters, and of course hams like the tunnel d iode- that interesting little chunk of theoretically-impossible negative resistance which has nearly rewritten the book on semi­ conductor physics. Shortly after the idea for «73" was born, this writer (half-humorously) suggested to \ Vayne that an article on "How To Build a

Head on view of front of riQ . Box is 4 x 4 I 2.

20 • 13 MAGAZINE JANUA RY 1961 Tunnel-Diode Transmitter" might he in line with the magazine's policy of bringing into r- ~_y;,50... 0". focus the frontiers of amateur radio. "Creat!" was the answer from \V2NSD. • "Hop to it!" 10 TO CIRCUIT The writer hopped. The only thing wrong was that this particular frontier seems deter­ mined to remain a soft-focus image. Whatever Fig. 2 laws of classical physics fail to hold with the tunnel diode, at least one is proved truer than One of the least expensive is the Ceneral ever before: Murphy's Law No. I -If in any Electric IN2941, a 50-milliwatt, 5 -milliamp project, any conceivable factor can cause the unit which sells for $6.50 each in unit lots. wrong res ult, it will! You can buy 100 of them for $450, if you want your troubles in large doses.O thers available for less than $15 include the T exas Instru­ ments I N653 and the Sony Esaki Diode (no type number) which sells for $10. The GE

• unit was used in this effort. For a bit of background on the use of the gadget, see the July, 1960, issue of Radio­ Electronics in which two CE researchers show how the negative resistance is achieved. A more scholarly treatment of the action ap­ I peared in the July, 1959, issue of the Proceed­ ings of the I.R.E. If you happen to read both these articles, you will discover that there are at least two - ways to go about build ing a tunnel-diode , oscillator, in theory at least. F or convenience, we called these "Type A" and "Type B" cir­ cuits. They're shown in Figure 1. Looking at the circuits, you see that the source of bias voltage-necessary for operation of the device-is specified as a 100-millivolt battery with zero internal resistance. Nat­ urally, such a varmint doesn't exist. Obtaining such a power source (or at least, something which would look just like it to the diode) lnhnior shambles. Messy loo ~ is due to short proved to he somewhat of a problem. leeds necessary for functioning of gadget. F ortunately, following the lead of the GE researchers, a circuit was developed which Before going into the long story of how we provides from 10 millivolts to 1.5 volts, with got lost in the tunnel, let's say right here that an effective 10-ohm internal impedance. It's this is a construction article. Before it's shown in Figure 2. This bias-source circuit, through, it will tell you how to build a tunnel without change, was used in both T ype A and diode transmitter that works. H owever, that's T ype B oscillators and produced perfect re­ only a small part of the story, and if you sults. H owever. there's a d isad vantage-due to want to stay out of trouble with the FCC, the heavy drain of the two resistors, the bat­ you'd better read it all. tery only lasts about a week. Be sure to dis­ As in the famed recipe for rabbit stew connect it when the rig isn't in use to keep which begins, "First, you catch a rabbit," this the battery alive longer. instruction must begin with "First, get a tun­ Now to the long story. The first circuit nel diode." This isn't so hard as you might tried was the T ype A, following the lead of believe. Most major electronics parts houses the GE people. \Vith various inductance catering to the industrial trade stock a few, values inserted in the tank circuit- and omit­ and almost every manufacturer of semicon­ ting all lumped capacitance-fi ne oscillations ductors has at least one tunnel diode in the were produced at several points between 12 line. and 20 megacycles. Modulation was accom-

JANUARY 196 1 73 MAGAZtNE • 21 Sensitivitv? Hardlv! Project went ~lown the drain and the II( HEADSET UNIT B·] writer went to sec the engineers. After several weeks' study, during which a number of ot her versions were constructed, tested, adjusted, retested, and lorn down, 10 TO DIODE Project A-9 wns p ut togeth er. It was d ifferent ,,, from all its pred ecessors. It worked.

Fig . 3 plished as shown in Figure 3A, and the re­ sulting F~ I-A~I combination was copinhle on a Super-Pro in the 2.5-kc bandwidth position although quality was definitely poor. This original attempt might have resulted in the article in itself, except for one item: Murphy's Law. The inanimate objects proved their perversity, for the blame thing ahso­ lu tely refused to oscillate within the borders of any amateur band. At 13.7 me, yes. At 14.7 me, yes. But between 14.2 and 14.35 me, no indeedyl After a week's effort, proj­ Ma in subassembly shown separa tely. Di ode a nd ect A- I was abandoned and the Type B circuit those resisto rs not part of power supply are was tried. shown. The Type B circuit evolves from experi­ ments carried out in RCA's David Sarnoff Re­ search Center. \Vhile the T ype A arrange­ Since its circuitry also differs, drastically, ment places the tank in series with the diode, it's shown in Figure 4. Note that no tank the Type B circuit places the tank uud th e circuit exists, in the normal sense of the word. diode in parallel. This makes them more The engineers deduced that irregular per­ tractable at SHF, although it has little effect formance of earlier models was due to exces­ at lower frequencies. sive inducta nce which forced them to oper­ T he target this trip was a 432·mc converter ate in the switching mode rather than as true consisting only of a tank, a diode, and the bias oscillators, so the 20-ohm composition resistor circuit. An 8-inch strip of twin-lead was was substituted. Its inductance is sufficient, used for the tank, and the l O-ohm resistor of in conjunction with that of the pigtails and the bias supply was used to provide the short the capacitance of the trimmer. to make the at the shorted end of the line. The diode device operate in the range from 50 to 150 me. was located an inch out from the resistor, and Modulation in this one is somewhat d iffer­ bias leads were run from the resistor through ent, also, as shown in Figure 3 8 and 4. DC l -uh rf chokes. resistance of the headphone unit is high Like the preceding circuit, this one oscil­ enough not to upset the biasing arrange­ lated nicely with ap proximately 100 milli­ ment, and ac output is great enough to volts applied.\Vhen the Super-Pro's antenna give a swing of nearly a megacycle in the lead was connected to the loading resistor 50-me region-far too great to be used be­ (a zero-voltage point for the rf with in the low 525.5 mc. oscillator) any number of TV carriers could H you want to build one of these. duplica­ be obtained. Varying bias voltage between tion of the Figure 4 circuit is recommended 70 and 150 millivolts tuned the oscillator as a starting point. It's far from perfect, but across many, many megacycles. However, the it can he used to amaze your fr iends, at least. signal from the grid-dipper which was simu­ \Vith a few months more work, it can prob­ lating an incoming 432·mc signal eluded cap­ ably he developed into a reliable hand-carried ture. After nearly 40 hours of searching with portable good for up to a mile or so, suitable the receiver se t in Sckc bandwidth position, for C D and transmitter-hunt usage. the signal was spotted-but promptly faded A standard 4x4x2 Minibox makes a good out when the d ipper was moved more than six chassis, with a subchnssis of light aluminum inches from the tuned line. inside to hold the tunnel-diode socket and the

22 • 13 MAGAZINE JANUARY 1961 and the like are out-every movement within 15 feet shifts the opera ting frequency a mega­ cycle or more.

\II .0 " SET TO 4 0 .1\ ~ tN294 1. I I T:~ '0 '0 ,,!.

Fig. 4

The t ank circuit (also shown in No.4). Cepecl­ This may sound as if the gad get is still tor is visible, resistor is partially hidden behind far from perfected. You're right-it is. The phenolic board. Incidentally, phenolic board was scrounged from old RCA printed circuit; only claim mad e for this gadget at the pres­ this is reason for stencilled numbers on it which ent time is that it produces modulated rf­ may draw questions. about 1 volt of it peak-to-peak into a I-meg­ ohm load. Location of this rf in the fre­ quency spectru m is not guaranteed. If it falls switch. Wi ring is straightforward, with one within the hounds of any ham band, you're exception : DOX'T C UT H ESISTOR L EADS SHOI\T! not just lucky, you must be the seventh son while component lead s should usually he of a seventh son of a sev . .• The gadget, as short in VHF work, this rig uses their in­ hinted earlier, is notoriously unstable so long ductance for a tank circuit, and if you dress as any reactance whatsoever is in the vicinity them in proper approved fashion, it probably -and this includes the varia tion in capacitance won't work at all. caused by the breathing of the operator. How­ The big problem with this gadget is ever, it does show promise, and that's why coupling of the antenna. If you have a per­ it's here. fectly-matched line which is actually a true Mean while, hack at the madhouse, experi­ resistance, it can probably be shunted across mentation continues. Someday soon, model the 20-ohm resistor without effect. However, C-293 may produce more useable results. If any reactance reflect ed into the circuit will not, you can still say you read about the be ruinous to its performance. Whip antenna battle first in .. . 73

" M echa niz.ed Hole Cutting" are commonly known, are becoming more and more popular a nd are a va ila ble with a wide Roy E. Pefenberq range of attachments. The Greenlee hole punch becomes a formidable tool when powered by one of these labor saving devices. The com­ The problem of cutting large r ound holes paratively light , r apid impacts of t he tool in heavy steel rack panels has long plagued drives the punch through the thickest metal t he amateur who uses this method of construc­ with great rapidity.T he wear and tear on the tion.Hole sa ws and Greenlee knockout punches punch and drive screw is much less and the have been used with va rying degrees of suc­ familiar problem of twisting off the drive cess. Of course the hard way of drilling a cir­ screw is virtually eliminated. cle of sma ll holes and chewing out t he rema in­ T hese handy tools have many ot her u ses ing metal is used by many but this is ext remely a nd any number of drilling, tapping and laborious and the results leave much to be threading operations may be accomplished in desired. addition to that of nut driving. Use one and Electr ic impact tools, or wrenches as they you will not be ha ppy u ntil you own one. •

JANUARY 1961 73 MAGAZINE • 23 8 M C CrystaI Modification

Donald A.Smith W3UZN Associate Ed itor

HE very popular Heath 6 meter transceiver meter transceiver for $4.95. This includes all T can now he modified for 8 me crystals, parts, even the necessary hardware! All new with Heaths new Modification kit, HWM-29-1. H\V-29's purchased will be shipped with this Following Heath's policy of improvement for modification kit and the customer billed for existing kits, this modification has been re­ $4.95. Kits shipped after the first of the year leased to all previous purchasers of the 6 will incorporate this change in the main

, /

Close up of oscillator and xial before modifica­ tion.

• • Another view of completed chassis. • -~ {) o • • 0 chassis and no modification will be required. • The advantages of this modification are .- numerous. Probably most important is f re­ - .. quency stability, which is improved for two ... reasons. First, the fundamental Quartz crys­ " tals are inherently more sta ble than the fifth - overtone types and secondly because the crys­ ~~ -~ tal oscillator is isolated from the final ampli­ fier. Other advantages include ; 8 me crystals are much cheaper and more readily available g than the overtone type. Power output is also \ \ \\ increased, as the final amplifier operates straight through and has more drive than with the old circuit. A modified P ierce oscillator circuit is used for the oscillator stage, employing a 6AK5 Parts fur nished with HWM-29.1 Mod ification tube. 8.333 to 9 mc crystals are used in the kit. grid circuit and the plate is tuned to the

24 • 73 MAGAZINE JANUARY 1961 third harmonic of the crystal. The output of the new oscillator is fed to the grid of the old oscillator stage, which now becomes a doubler \V stage. The new circuitry does not overload the ac power supply and one Hea t h vibrator '0 '0 supply is still ample to operate the unit while ( t~~ IPzN...TOO£)· mobile. esc. Me ,.'" Me _- - !)TH OVERTONE "'''' T ORIGINAL TR /l ,.. SMI TTER 61.OCK \V ,"U8 ,..... ",. •• O!lCLATOR:.." "2 {TRlOOEI {PEHTOOEl Me Me TRIP\.ER Me OQUlll.ER Me ,.... L _- 8333.9111C T XTAL

Block diagram of transmitter before and after modification. 1 I socket a nd the rig t urned on. Tune up was Close up of tr ansceiver with new circuit in­ then like a ny other r ig. The oscillator slug shlled. was tuned to 25.2 me, the doubler to 50.4 and t he same for the fi nal. No parasitics could be .One of the photos shows the parts included found and the circuits would not double t une. In the modification kit. Note that a miniature Air trials were most encouraging. Stations chassis is furnished and all new parts are worked in York, Pa., approximately 100 miles mounted and wired on it. The new crystal over the mountains asked if I had increased socket for the 8 me xtals is mounted on one power! Frequency stability was terrific. I had end of this chassis and takes the common F T· a station in York zero beat my signal with 243 size. Complete instructions for wiring the his BFO. Then I cut my carrier for 60 seconds n~w oscillator circuit a re included, as they are or so and then t urned back on . He said that with all Heat h kits. It is necessary to drill two I was still zero beat ing with his BFO!All in holes in the f ront panel of the transceiver to alI, signal reports were somewha t better than mount the new chassis.A template in the before, plus f requency stabilit y and a lack manual simplifies the la yout of these holes. The s~ow . of FM. photos the unit completely wired before For an investment of $4.95 a great deal installation In the unit so that you may see more pleasure and reliability can be had from the wiring. your little H\V-29. 73

TO fO~MER XfA.L SOG ~ET '0'" R A NSCE IVER

••• , I OO ~ •• < 6.3 \\1.e > .ocr

THE " SIXER"

n 12VAC 6\1AC ~---* 5/32 "MOUNT~G HOLES Circuit diagram of new, added circuit. 'j\\~:!::: ••• No di ffi culties were encountered in the build­ POWER OUTPUT ing or installing of the modification kit and it 1 equired about an hour or so to complete the job. The real enjoyment began when a n Tem pl ate for locating two holes to be drilled 8.4 me xtal was installed, 6AK5 placed in its in front panel of th e transceiver.

JAN UARY 1961 73 MAGAZINE • 25 Bu ild a Transistorized Crystal Frequency Standard

Howard S. Pyle, "YB" W 70E 3434-74+1'1 Avenu e, S. E. M ercer Island, W" shington

F OR some time I had been debating construc- tion of a transistorized crystal frequency standard. A number of crystal aut horities whom I consulted warned me t hat not only would the crystal and the transistor be rather critical but that lead length and routing of the wiring would affect the frequency of even the. best. crystals. All suggested procuring a baSIC umt. sub-assembly, wired and tested by an established factory specializing in pre­ cision crystal/transistor work. I could then build around it with the assurance that per­ .~, formance would equal expectations. ....n u ... . Their. arguments, seemed logical, although it did begm to look hke a rather expensive pro­ ced ure. At a ny rate, I commenced shopping around.I didn't want a frequency sta ndard for kc and the TRO-3, 15 to 60 megacycles, in which I had to use a compensation curve : I fi ve ranges! Anyone of the three basic units wanted 'on-the-nose' accuracy without a 'lot will cost exactly four dollars; the first sur­ of namby-pamby, although I had visions of prise! The precision ground crystal is. of the greatest J?art of a fifty dollar bill going course, the greatest cost; $8.50. Several manu­ down the dram! That it didn't. continues to facturers offer precision crystals for fre­ amaze me. You know what? I came out with quency standard use at from $6.00 to $10.00, 8 . total cost. ~or the basic unit including tran­ but it is recommended that the crystal which SI StOI', precraron ground crystal, cabinet, bat­ the manufacturer has used to calibrate the tery a~d toggle switch for around fifteen dol­ oscillator be purchased with the basic unit to la1's, grve or take a few cents! insure complete accuracy. The same would After poring over several excellent 'dope hold should you elect to purchase a sub-as­ sheets' sent me by various manufactur-era, I sembly of another make. finally selected the Interna tional Crystal This little unit can be mounted right on t he Manufacturing Company" Type TRO-l basic chassis of your receiver if you li ke; practical­ sub-assembly. This was the complete oscil­ ly a ll modern receivers still have a bit of lator unit, miniaturized and completely as­ space available for such a tiny item, in spite sembled, wired and tested. It measured but of their many components. Or, you can do as 1*" square by 2" high with the crystal in I did so that you have a really flexible piece place. The wiring was of the printed circuit of equipment available for bench testing as type insuring against any change in routing well as checking your receiver; mount it in due to vibration or other causes. External its own separ ate cabinet. wiring required consisted only of the battery The accompanying photograph illustrates leads and the rf output feeder. This little t he treatment which I used. As its power re­ unit was capable of oscillation within the quirements are only 9 volts de at 2 rna, I frequency range of 100-300 kilocycles or 200­ chose a Burgess type D6 batter y and used a 5000 k ilocycles, with t he proper crystal ! Their conventional. bat-handled toggle switch with T RO-2 sub-assembly will covel' 3000-20,000 which to turn t he power on and off. I wired t his into t he negative battery lead ; note t hat -19 North Lee. Oklahoma City. Okla. the positive lead is grounded. Actually, with

26 • 73 MAGAZINE JANUARY 1961 this small current drain, such a battery will slightly ; it should bring you right on with a last for many months without turning it off, minute fraction of a turn. Set for zero beat but for complete fl exibility. particularly when and you've got it made . .. that's all there is installed in your receiver, use a switch. to it! For t he r f output I used a sta nda r d phono pick-up j ack available at any ha m radio store. A short lengt h (6" in my case) of fl exible, -.. st ra nded hook-up wire fi tted with an a lligator . ~ TRA NS ISTO R ~ 3 0l(.. - ~ # ~ clip at one end a nd t he plug of the phono APPl'IOX,2200 j ack a t t he other per mitted feeding the rf OHMS LOAD 1'011 o 8£5T RESULTS out put of t he oscillator into my receiver or o • a ny other device as required. C O• "'""- eo T he enclosing cabinet which I used was an • 'iT' ,o 'n , LM B chassis box which is also a stock item , , with most ham distributors. The one I chose ~ ,, co was Ll\I B's #140 of hammartone grey fini sh ,, and which readily accommodated all compo­ ~ . o nents including the battery.I fitted this with Te.' small rubber feet and bent up 8 sma ll alumi­ ~-~ num sub-chassis on which to mount conde n­ -90 6~, · ser C. This is merely a small trimmer conden­ : c/ S WIT~ ser of 7-45 mmfd ; t he one I used was an E rie, L.. --~ N-500 (most distributors ); any equivalent --''I IIIATTERY' will do. It permits compensating for any minor variation in frequency which ma y be If you st ill feci that you'd like to build 'From introduced by the cabinet and the internal scra tch' without benefit of a basic unit and wiring therein; though you may not need it, make your own calibration (it may prove put it in, just in case. A % t , hole in the cabinet tricky!). the Inter nat iona l Crystal Manu­ top, insulated by a rubber grommet, permits facturing Company has been kind enough to adjustment of this condenser externally, if and give permission to reproduce the circuit which when required. they use on their TRO·IL sub-assembly. to­ To put your frequency sta nda rd into op­ gether with component values. Like the trim­ eration, set you r receiver initially on one of mer condenser C. the fixed condenser C5 is a n t he on-the-nose frequencies of WWV, WWVH accessory item, not supplied with the THO-IL or some other known accur ate frequency trans­ sub-assembly a nd which you mayor may not mission of t he fundamental 01' harmonic fre­ want to add . It merely serves to improve the quencies of your sta nda rd. Clip the rf out put wave shape of the output which was of no con­ of your frequency sta nda rd on your receiver cern to me, therefore I Ignored adding it. antenna post in place of your regular antenna, Go to it but remember that j ust any old and turn the switch on the frequency sta nda rd crystal, transistor a nd circuit are lia ble to to the 'on' position. If you don't hear the C' V cause you headaches! A frequency sta nda rd is tone from t he frequency sta nda rd, adjust C a precision device; bet ter play it safe ! moo

Polarity Test Paper

Bob Rooney, W 2Q Cl inches. In the case of d irect current a bright red stain will appear on the test p aper near One of the simplest ways to find the polarity the nega tive terminal. W hen a lternating cur­ of current is through the use of polarity test rent is used the red stain w ill appear at both paper. From two common chem icals which terminals. can be obtained at the neighborhood phar­ To prepare the test paper we can take any fairly absorbent paper (t'Slick" paper such as macy. it is possible to make an a lmost un­ that w hich 7 :-1 is printed on is not recommend­ limited supply of this paper quickly and eco­ ed ) and b riefly soak it in the solution d e­ nomically. scribed he low. Allow the paper to dry and 111 lise, the paper is slightly moistened and merely moisten w ith water before usc. placed ill contact w ith the two terminals of The solutiou is prepared hy mixing on e part the current supply so that the terminals a rc p henolph thalein solution to three parts of 10% separated from each other by ouo or two potassium chloride solu tion. •

JANUARY 1961 13 MAGAZINE • 27 • •• • c ------...

• •

Suction

vs Whooosh Fig. I

Pe ul M. Borton W6JAT J en nings Re dic P. O . Box 1278 So n Jose 8, Col.

A ssn Linear Amplifier using a 4CXIOOO tube was set up in Jennings type con­ struction, but with provisions for supplying cooling air either from th e bottom, or the top of the tube in severa l ways. Fixed b ias batteries and a variable screen supply were used to set th e plate current where desired. 3500 volts of plate voltage was used. As there was no rf power involved, all th e de plate input was being dissipated

28 • 73 MAGAZINE JANUARY 1961 by the plate. With diffe rent types of blower series only yield a small increase in air systems, and for several amounts of de plate through the tube. input, the resulting plat e temperature was Now a glass chimney was placed over the measured wi th a thermocouple and alter­ tube plate fin s and a blower was set on top nately with temperature indicating waxes. of this chimney so the blower drew its air First, the chassis was pressurized in the through the tube, and blew it out into free more common manner. by blowing directly air (Fig. 3). With 700 watts plate input, into the chassis, as in Fig. 2, but w ith the the anode came up to 230°F, compared to bottom plate removed, rotated 1800 and re­ 260°F with th e same blower acting as a placed. This places th e blower to one side of blower instead of a sucker. the tube socket instead of d irectly under the The asumption here is that the sucker ar­ tube socket. \Vith 700 watts plate input, the rangement is able to draw more air through anode temperature came up to 260°F. All the radiators due to less losses in the tube tests were run until the resulting temperature socket, as considerable air will be drawn stabilized. through the tube radiators that did not have It is generally assumed that this simple to go through the socket at all (the tube base method of pressurizing the chassis is inefficient and filament seal still remained cool enough, due to turbulence, so the blower was plumbed however) . into th e bottom of the tube socket with a care­ Now the power was increased, using the fully fitted short direct duet (Fig. 2 ). The sucking arrangement, until the plate tempera­ resulting plate temperature was the same, ture came back to 260°F. This required 825 small increase with two blowers instead of watts, an increase of 18% over the blow one should be expected as two blowers in system. As an adequate blower for air cooled tubes Fig. 2 is quite expensive, this apparent 18% increase in effectiveness, is well worthwhile. It is not held that sucking air through the tubes is more effective, but that it is possible to plumb to the tube more effi ciently by sucking. This system has been used in a number of 1 kw amateur amplifiers with excellent re~ suIts. The rig pictured belongs to Elvin Feige, W6TT, the well-known dx hound and boating enthusiast. 73

Fig. 3

however. The assumption now is that the tube socket itself makes so much air losses that the chassis turbulence is of minor im­ portance (Fig. 1 ) . Next, the above two tests were repeated but with two blowers in series, the fi rst blow­ ing into the second, and the second blowing into the chassis or tube base. Now the tem­ perature only came up to 220°F, as one might expect. Now the plate input was increased slowly until the plate temperature came back up to what it has been with only one blower (260°F). One hlower required 700 watts to bring the plate up to 2600F, and two blow­ ers in series required 940 watts for the same temperature. This is an increase of 29% . This

JANUARY 196 1 73 MAGAZINE • 29 H MS Joergen K. Resmusen. OZ7BO 3 1 Bcrqevej Lyngby AN Denmerk ALL TRANSISTOR COMMUNICATIONS RECEIVER

LTHOUGU transistors have been available using a bandswitched converter. Selectivity is A for sever a l years, t hey are not as widely obtained with two sect ions of a half-lattice used in ama teur equi pment as one might ex­ filter on 480 kc. pect. Amateurs tend to believe they are dif­ fi cult to work with and troublesome. The transistorized communications receiver to be The Converter described should prove that this is not the case. The "front end" uses 3 transistors as the The receiver uses 14 transistors and covers rf amplifier, mixer, and crystal oscillator. AI. all bands between 80 and 10 meters. To obtain though the first if is r ather high (3.5-4.1 me), the best stabilit y, the main receiver covers 3.5 and images are no problem, it is necessary to to 4.1 me. Other frequencies are obtained by use high "Q" coils in the rf section to prevent

30 • 13 MAGAZINE JANUA RY 1961 if and spur ious signa ls from feeding through. F T-241 crystals. T he two filter sections must T he antenna coil is tuned with a 4- 40 mmfd. be well shielded to prevent stray coupling be­ trimmer. T he collector coil is tuned broadly to t ween the input and out put leads. The fi lter is t he center of the band. T he crystal oscillator followed by t wo amplifier stages a nd a diode ~ works di rectly on the cr ystal frequency and detector. A beat frequency oscillator is a lso ;~ harmonics are used for the injection voltage. coupled to t he diode, and its frequency is con­ On 7 mc there is a problem in choosing the t rolled by a va ria ble capacity pitch cont rol. oscillator f requency. To obta in 7 me, we must T he transformers a re standard vacuum tube add 3.5 and 3.5 me (crystal oscillator and vari­ types to which 50 turn base windings have \ able if) , but since the receiver will tune to 3.5 been added. • me a "hirdie" will be heard. Actually the "birdie" will be a n eagle, it blocks t he receiver The Audio Amplifier 20 kc on either side of 3.5 me. A practical solu­ tion is obta ined when the 40 meter crystal T he audio amplifier consists of fi ve transis­ oscillator oper ates on 3.3 me. The receiver wiII tors, including a class B, push-pull, out put then tune 6.8 to 7.4 mc. stage. Bet ween t he first and second amplifier Since the oscillator operates on the crysta l will be found an FL-8A war surplus a udio frequency, no coils are r equired, a nd out put is fll ter to increase C\V selectivity. The t hird applied to the mi xer through a 10 mmfd. capac­ transistor is a driver f or t he output stage. itor, Signal mixing takes place in the base The transformers are standa rd impedances , circuit of t he transistor. and American equivalents will make excellent The collector of the mi xer is not r esonated substitutions. The sidetone connection is wired at the va riable if but uses a n r f choke to obtain to a neon bulb oscillator and is keyed by the a broad bandwidth, and easily covers the 600 C\V transmitter. kc range. The Variable IF l The first, or variable, if tunes between 3.5 a nd 4.1 me, and a lso uses three transistor s. The oper a tion of t his circuit is quite similar to the conver ter bu t, of course, is tuned to the lower FREO frequency. CORECTOR-_ Input to the vif mixer base arrives from C3 the antenna on 80 meters and from the con­ cz __ ver ter on the other bands. To avoid tracking osc problems t he mixer base and collector tuning SECTION ca pacitor is not ganged to t he oscillator . These 06-- BASE two a dj ust ments are set nea r opposite ends of VOLTAGE the band for a fl a t response across the variable A!>JUST if· FIRST HALF The variable oscillator is the heart of t he LATTICE r eceiver for it must be very sta ble. This is not FILTER difficult for the transistors are low voltage and current devices a nd t herefore are not able to B'O-_ hea t t he adjacent components. The coils a nd capacitors should be of rugged construction a nd solidly mounted to the chassis.F or the most part stability will be determined by the de stabilization and, to a certain extent, t he room temperature. To provide the cor rect impedance match to t he oscillator coil, t he collector is tapped % rd f rom t he hot end a nd t he emitter about }'bt h from t he cold end. The output is taken f rom a link wound over t he cold end of the coil. One The Transistors end of the link is soldered to the emitter of the mixer tr a nsistor, a nd t he other end is con­ The transistors used in the r eceiver were nected to ground. T he oscillator and signal f're­ made by Philips of H olland, but are available quencies mix to produce a second if of 480 kc. in t he U nited States under the name Amperex. If your distributor does not car ry t hem, Radio The Second IF Amplifier Cor por ation of America makes an interchange­ able series.Tbe OC170 and OCl 71 t ypes may In t he second if selectivit y is obtained by be replaced with the RCA 21\384. T he OC44 means of two section half-lattice filter using is a junction transistor wit h a cut-off fre-

JANUA RY 196 1 73 MAGAZINE • 31 • •

I I I I• I- 1 I , I -- I .. - I I - I I - l...... '.

• • ..

H-I· - • • •• ·t

• I

Fig. I-Schematic diagram for the transistorized receiver. All 0.01 capacitors are

1I-40 meters. 4.05 ,u h, IS t urns. tap 3 t urns up from On 40 wi nd 2 t urns per g roove, others I turn cold end. Link is 3 turns tit col d e nd. per groove. 20 meters, 1.0 1 p.h, 5 turns, tap I turn up from 13-40 turns. 12.65 ,uh, tap 10 turns up from cold end, ~ cold end. link I turn. link 5 turns. 15 meters. 0.77 p.h , 4 turns, tap 112 t urn up f rom l 4-Sorne es L3, but no tap. co ld end. lin k I t urn. l 5-36 t urns, 12 ;,th, collector tep 12 turns from hot 10 me ters, O.77,uh , same as 15. Spacing-I t urn end, emitter tap 6 turns from cold end, lin k 5 covers two grooves on 10 and 15 meters. turns ot cold e nd. l3, L4, L5 wound two turns 12--4Q meters. 16.9 ,uh , 35 tu rns, lin k 5 turns. per groove. 20 meters, 4.2 ,uh, IS turns, lin k 3 turns. Cia, b-V<'.lr ioble if peaking, duel 5-60 mmfd. 15 meters, 1.9 ph, 8 t urns. link 2 t urns. C2-JOO mmfd on 40, 20, e nd 15, noneon 10 meters. 10 meters, 1.05 p.h , 4 turns, lin k I turn. C3- 50 mmfd on 05 11 bends.

quency of approximately 7 me, and the 2N113, rate de stabilization. This can be obtained in 2Nl14, or 2N137 should make an excellent one of two ways. One method uses a resistor in substitution. The OC45 is a junction transistor the collector and one in the base. T his cir cuit is and has a cut-off frequency of 3 me. The employed in circuits where constant base vol­ 2N140 will replace this transistor. The OC70 tage is not essential, such as the audio ampli­ and OC71 may be r eplaced with any general fi ers in this receiver. The best method uses purpose PNP t ype. The OC72 is a medium four r esistances. One is in the collector , one power transistor and has a maximum dissipa­ in the emitter and two (as a voltage divider) tion of 165 mw a t 25°C. The 2NI09 can be in the base. This system provides excellent used in place of this transistor. stabilizat ion and therefore is used in variable To prevent transistors from burning out at oscillators and rf amplifiers, as in this receiver. high temperatures it is necessary to Incorpo- To make base bias adj ustment easier, potentd-

32 • 73 MAGAZINE JANUARY 1961 • -_._-....-

- - - • li' ~ ~ " ~ " ~ - _. •• •• " j~ ~ • ~ 11:_ o l"- '" • - • • '" ~ !·f •• •• • • • • • • • • • • • - • • • • I r rrr: » > -- ~ '~J .~ - .. +- l e' ~ . ~ I ~'e ,"" .- ~ ~ - r: ... .. '" • • • • • • '" - iT- • • .. _- T

-. oM • jf-:m" - ~'f .. ·t

ceramic capacitors. Coil data is given in the accompanying chart (Fi3' 2) .

0 1. 02. 0 3. 04-0 CI 70, 2N J84. t urns of fi ne W i fe ove r one winding (bose OS, 06, 0 7. 08-0 CH [see text ], li nk ). 09-OC45. 2N140. TS-Pe rmeobility t uned if Ill -TS may be modified 010. 011. 012-OC70.OC7I [see te d) . M;lIe, # 9 IJ-C I) . 013. OI4-0C72 . 2N 109. 2N2 17. Tb-IOK to 2K et (Triad TY-56X ). RFC I, 2. 3-2.5 mh rf choke. T7- S00 ohms to 8 ohms (Trio:l d TY.45X) . $1 --6 pole, b position wofer switch. YI - 3.3 me. TI, T2-Permel'J bility t un ed if mod ified by replocing Y2-IO.5 me. one cepecltor with two series con nected Y3- 8.75 me. capacitors provid ing the same total co p"­ Y4-12 .25 me. city. Y5. Yb-FT24I surplus, Cha nnel 57. n. T4-Pe rmeobility t uned if modified by winding 50 Y7, Y8--FT24 I surpl us, Chennel 58.

ometers are u sed as the bias divider. adjust the frequency of each coil to its normal resonant frequency. Insert the variable oscillu­ Adjustments tor transistor in its socket a nd listen for oscil­ lation on another receiver. T he oscillator After the wiring has been completed and should tune between 3.01 and 3.61 me. An checked, it is time to adjust the receiver. osc illat ion will also be indicated by a change Measure and set the drain of the transistors, in collector current when you touch the hot using the potentiometers, at one milliampere. end of the coil. If the circuit is working prop­ Set the push-pull stage to draw 5 to 7 mao erly, the current will r ise. Use t he sa me pro­ Next, remove the transistors from the rf cedure with the beat oscillator and crystal amplifier, mixer, oscillator, and 1st if mixer oscilla tor. Replace the filter crystals with 10 a nd oscillator sockets. wttb a grid dip meter, mmfd. capacitors and connect a signa l genera-

J AN UA RY 1961 73 MAGAZINE • 33 Connect an audio signal to the second af stage and adjust the collector current of the CONVERTER pu sh-pull sta ge for the best waveshape as SECTION viewed on an oscilloscope. Insert the remaining transistors and connect • an antenna to the receiver. Set the receiver on 80 meters and connect an rf signal generator which tunes 3.5 to 4.0 me. Set the generator at 3.5 me and adjust the coil slugs (L3, L4) for maximum gain with CIa, C1b, near maxi­ o,, - -\-' mum capacity. Next tune the generator to 4.0 me and retune C1 for maximum gain. The C4 -~ signa l st rengt h should be about the same at both ends of the band. CIAR!" AMP 07 The la st step is set ting up the converter 74 section. Switch to 40 meters and adjust the 40 meter LI, L2 coils for flat response across the ham portion of the band. Repeat this process on the remaining ham bands. The receiver should now be ready for use.

TO

SfCOND HALF' LAT1lC£ f'l...TER OE TECltlR tor (at 480 ke) to the base of the 2nd mixer. Connect a voltmeter across t he diode load (10K) and adjust the if transformers for maxi­ mum gain (keep reducing the signal so that t he diode voltage reads less than one volt. In­ sert the crystals and repeak t he transformers on each side of the filter for t he strongest signal, consistent with flat response.

L5

Transmitting

Since transistors are voltage sensitive, it is necessary to protect the rf amplifier transistor with some form of switch or relay in the line. At OZ7BQ a TR switch of the cathode follower type (connected to voltage divider on tr-ans­ mittel' tank) is used. This system gives good protection on a 100 watt transmitter and the final amplifi er tank does not function as a trap. The final tube (s) must be run cut-off in receiving periods so that noise is not generated. Several methods of receiver blocking have been tried. The smoothest break-in was obtained SlOE -TONE lNPlIT when the variable oscillator was keyed off with a positive base bias.

34 • 73 MAGAZINE JANUA RY 1961 Layout ceivers a nd is equa l to them on all bands. The maximum volume, of course, is somewha t The chassis layout is somewhat unconven­ lower, and reception is best with headphones. ti onal. Ea ch sta ge is mounted in a sm all box. The power could be increased from 200 mw to This provides excellent shiel di ng a nd permits mo re than one-half watt by using- a 12 volt each st ag e to be removed for circuit changes. s upply on t he class B st ag e. • The boxes are made of t inned metal from coffee With no sig na l the cu r rent drain is 15 to 20 cans. The boxes are soldered in such a manner rna, and it kicks up to 140 rna on audio peaks. that you can reach the parts when t hey are The use of a 6 volt su p ply permits the receiver mounted on the front panel. For rigid con struc­ to be used at home, in a n a utomobile (new or t ion, t hese boxes are mou nted to t he front old), or port able with t he sa me excellent re­ panel with sever a l screws. The oscillator vari­ sults. 73 able capacitor is mounted directly on the front panel. Even when t he receiver is given quite a Fig. 2-The coils with the " L" prefix are wound blow it shows no signs of f requency instabilit y. o n this t ype of form . Any slug tuned form of La you t of the components is not cr itical if t he this a pproxima te diam eter a nd length sho uld rules of tube construction technique are fol­ be sa tisfa ctory, atl houg h the grooves mak e Jawed.P hotos of the receiver, which measures winding easie r. Numbe r 26 e nam. is used for a ll 7" x 8" x 12", show the assembly a nd layout. coils.

Conclusions

Many things have been learned by con­ st r uct ing and operating t he t r ansist orized com­ munications receiver. The oscillator drift is / less than 1 kc in warmup. T he sensitivity has IRO N CORE: been compared with modern American re-

New Products

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Two Meter Transmirter-Recelver The H ea t h " Pawnee" is a comple te two me ter trensmitter with VFO o r crystal control a nd 10 wa tts rf o ut pu t to the entenne throu g h a low pass filter t o e liminate TV!. The recei ver is d ouble conversion and of high stability. A three-way powe r supply is bu ilt in: 11 7 vee. 6 o r 12 vdc. C omes complete with buil t in spe a ker, mounting bracket and ce ra mic mi ke. MM sures 6" x 12" wide x 10" deep, 34 [bs. Price in kit fo rm: $ 199.95 from the fa ctory, The re are a lot more juicy details you ' ll want to kn ow about on th is so dro p He a th a line at Be nto n Ha rbo r, Mic higa n so t hey can fill you in.

JANUARY 196 1 73 MAGAZINE • 35 •

A Novel, Light-Weight, Low-Cost

ANTENNA SUPPORT MAST

and Vertical Radiator

This unique design results in a sturdy, easily handled and effective support fo r a horizontal wire antenna as we ll as 'doubling ' as a ve rti­ cal radiator. Weight is less than 35 pounds and the cost is under $15.00!

Hcwe rd S. Py le W70E HH-74th Ave., S.E., Mercer lslend. Wesh.

ORE substantial and less costly ccnatruc­ M tion of both vertical and horizontal wire antennas shou ld prove a welcome addition to amateur radio design practice. Presented here is an innovation in the way of a combination a ntenna support mast for wire antennas which can serve as well as a vertical radiator f or those who desire to experiment with both an­ tenna types. Better still, it is so light in weight t hat it ca n easily be erected by two men, one holdi ng down the base while the ot her 'walks it up'. If more help is available, put a man on each of t wo of t he center guy wires for added insurance against bowing and swa ying during erection.

P art, Lilt A-2" galvani:r.ed iron pipe 2" diameter by IS" long ,a. ( 4 required) D-Pulley block of your H - P o r c e lain insu lat ed choice IlCrew e}'es-(G required) C-Dow n -h a ul rope or cable I - .;;a solid galvanized - abou t 35 teet required iron wire D-Shackle or auto tire J- 2" diameter gah·ani:r.ed ebetn repair link iron rain pipe 14 ten E--Gal\'an i:r.ed eye a bolt" foot lengths r equired ) JA" X 3" with nut (in­ K -2" #12 b rass or &,a l­ eu la ted eye type) vanleed iron round-head F-#8 x %" galvanb.:ed wood screw sheet m etal IlC reW8 (42 (Unless otherwise specified. required) only 1 each of above itt-rna G-Wood re-inforcing plug, required.] l6 • 13 MAGAZINE JANUARY 1961 While some difference of opinion exists sn ips. Procure from your local lumber yard, among various authorities as to t he proper a six foot length of what is known as "full­ height of a vertical r adia tor for amateur r ound" wooden stock in the 2" size. Cut it into usage, popular pra tice seems to favor 33 feet , four 18" lengths. T hese will serve as 'plugs' plus or minus a foot or so, depending u pon the or connectors between sect ions a nd are shown desired r esonant f requency of operation, cal­ a t "G" in F ig. 1, a nd as " A" in Fig. 3. Use culated f rom existing formulas. Such a height t hese to connect the sections, drivi ng about is t he equivalent of a quarter wave-length in half of their length into each end of the rain the 40 meter ba nd, a half-wave on 20 and full pipe and securing them with sheet metal scr ews wave on 10 and works well on all. On 15 met­ as shown in the drawings. Butt the ends of the ers, the efficiency is but slightly impaired and metal pipe closely toget her and run a generous is really a matter of no concern.In the 75/80 solder bead completely around the metal joint meter band, f unctioning as a vertical radiator, for elect r ica l contact between mast sections. Do t he mast is somewhat less effective than at not depend on this however; mechanciaUy, the higher frequencies, but as t he 75/ 80 meter wooden insert w ill be adequate. Electrically, a hand is not considered a 'DX' band, the excel­ Iltle w ind swa y in the mast could conceivably lent ground wave propagation of a vertical break t he solder seal a nd destroy t he elec­ of this height a ssures reliable communication trical conductivity. So, make sure of this by over sever al hundred and often a thousand or st r a pping the sect ions toget her with galvanized more miles, dependent upon transmitter power. plumbers tape or ground st r a ps of copper at 'Ve have therefore set tled on the mechanically all three points (120 degrees apart) as shown practical height of between 32 and 34 feet a t OlD" in Fig. 3. This 'ta pe' or st r ap metal is which, in addition to being very effective as a generally sold in ten foot coil s and one roll of vertical radiator, also permits a horizontal wire ten feet will be suffi cient for all joints. Use a ntenna to be installed at a satisfactory sheet metal screws as in Fig. 3 to hold it in height above ground level, if desired. place a nd then make it a good electrical j oint T he mechanical st r uct ur e itself is somewha t by flowi ng a solder bead a r ound it as in "E" unique in that instead of using a wooden mast of Fig. 3. Not only will these straps insure or pole, with copper tubing down the side and good electrical conduct ivit y for your rf, but the topped with a 'whip' antenna, or using water mechanical strengt h of the joint will be greatly pipe, electrical conduit or irrigation piping, enha nced as well. rain-pipo of the 2" galvanized, r ound type is Your next step will be to sa w, or cut with used. T his is available from hardware stores, tin snips, the excess length of t he initial 40 builders supply houses and plumbing dealers feet of mast assembly. Determine the length practica lly a nywher e and a t nominal cost. In of the mast from handbook formulas a nd cut the writer's ar ea, it is pr iced at 15c per foot the top section to br ing t he over -all length into and comes in ten foot sta nda r d lengths. This means that you will need four of the ten foot sections and must necessarily discard a por­ tion of one if your mast will 'double' as a ver­ tical radiator and is cut to r esonance. The few feet you discard however, r epresent a very sma ll loss which can be disregarded in view of the low over-all cost of the complete mast.

Mast Assembly $ttTlOff THAU 0-0 As supplied, pipe sections are fluted at one end for a few inches to permit telescoping. Cut off the fluted end with a hack-saw or tin "-/ ~0,+ _ P a r h List A-2" diameter g a lva nized requ ired) ~ H iron rain pipe ( 4 t en [-Braid from co-axial en­ foot leng t hs required) ble to g round damp on R-Balsa wood s pacer strips "J" ®~- : [see t ext ) J -Five or s ix foot copper­ / 0 - 10-24 Ga l vanized or clad steel g round rod TO ~ brass stove bolt , 3" long K-Ma stic or roofing pitch TfIl.AMSWfTUI D-Wooden erose-a r m in­ waterproofing (see text) s u lator pin (see tex t) L--Petticoat type of pole E--Solder lUll to fit "C" line insula tor {see text) I and " H" M- %" x # 10 pan-headed F-Gah-ani1ed split lock sh eet me ta l screws (2 reo­ w asher to fit " C" qu lr ed) CD • G-Gah'ani1ed o r bra s s nVhere no quantities specl­ 10-24 nut fled, one o nly o f item list ed. H - Co-a x ia l cable (RG 8/U r equtred.] or RG58/U) (length a e . ,I ,

JANUARY 1961 73 MAGAZINE• 37 conformity with your calculat ions. Remember available in all TV and radio stores for a few to mea sure f rom the point of feeder connec­ cents. By so doing you don't have small radials tion at the base ("C" in Fig. 2) to what will and poor rf contacts to upset your theoretical be the top of t he mast. calculations for antenna height vs. frequency. Insert t he final plug into t he top of t he mast And you'll find it a big help in avoiding TVI and d rive it flu sh, secur ing with sheet metal which could result from microphonic contact screws as shown at "F" in Fig. 1. T o prevent between guy wires and mast! rain drip f rom going down the interior of the OK; mount three of these insulated screw­ mast and r otting t he wooden plugs ca p the eyes about 16" down from the top of your mast, top eit her with a 2" galvanized pipe cap ("A" spaced 120 degrees around the circumference. in F ig. 1) or a coffee ca n lid and a wooden, They will serve a s anchors for your upper rubber or plastic ball, if you want to be r eally ser ies of guy wires (see " H" in Fig. 1). Do decorative. Toilet tank floa t balls, either plastic the same at either t he ten or twenty foot level or metal will serve well here if you don't ca re of t he mast; they will anchor your second set for t he fla t treatment of a pipe ca p. of g uys. J prefer the t wenty foot level but do as you see fi t. You ca n even drive an addi­ Mast Hardware ti onal wooden plug half-way into the second Your assembly of the mast itself is now (from bottom) sect ion of t he mast if you want complete. \Ve assume that you ha ve, of course, the lower guys at a point about half-way up; paid proper attent ion to supporting it on sa w the decision is yours.Remember to 'stagger' horses or boxes so that it assumes a perfectly the screw-eyes a t least half an in ch in the level forma t ion which will insure a plumb vertical plane or their shanks will collide! and pleasing appearance when erected. A six­ And now, the final hardware mount; the teen or twen ty foot length of t,4" x 1%" lattice eye-bolt at the top of the mast (a few inches (rea l cheap at lumber yards) makes a good below) which will receive the pulley block for str aig ht edge, when used edgewise, to check the down-haul for t he wire antenna. This eye­ this. Your next step is installation of a few bolt should also be in sulated and can be a gal­ hardware items on the ma st. First, let's mount vanized type, three inches long, going clear the guy wire anchors. If this were to ser ve only through the mast and wooden plug as shown in a s a support ing mast for a horizontal wire F ig. 1 at "E". The pulley block itself can be antenna we could get by here with conventional anything you choose; galvanized iron, bronze, galvanized iron screw eyes or eye-bolts. How­ wood block with metal shea ve, etc. Connect the ever , a s we might want t o use this also a s a eye of it to the eye-bolt in t he mast with a vertical radiator, either initially, or later, why conventional 'shackle' ( hardware st ores or not make provision for such use now? So, let's marine supply houses) or, if no local sour ce use the ineulatcd type of screw eye, commonly for shackles, use an automobile tire chain r e­ pair link, available at any automotive ser vice st a t ion, tire shop or auto supply st ore. - '--- Now, if you have your guy wires in place • ! and your down-haul riven through the pulley .,I shea ve, you need only cut the guy wires every fifteen feet and insert a suitable insulator. • This should preferably be of the compression type as, in the event of breakage, the guy , , does not let go. The sma ll, glazed porcelain type known a s 'airplane' st r a in in sulators, are ideal; these sell for less than iOc each at most r adio stores. \Vith their installation, work i -, A , on the mast itself is now complete, mechani­ eally. \Ve recommend t hat you now give it at least t wo thorough coats of a lead base paint in any color that suits your fa ncy.Not only will this act a s a preserva t ive against r ust, but , will considera bly improve t he appearance of , your fi nal mast. , •• P arts List

A-2"x18" le ng t h of 'fu ll_ De-Perforated steet st ra p­ round' wooden pole (4 about t en feel r equired I reouir-ed ) (see text} 8 -2" diamE' tE' r galvanizeod • E--Solder application (see I .~ iron rain-pipe (4 tE'n foot . , text] I lE'nKths required] • e-II.:" x # 8 pan-head gal­ vanized s h e e t m e t a l scr ews ( 12 ut eneh joint)

38 • 73 MAGAZINE JAN UARY 19b I Mast Base Mounting Again you don't have much of a problem in tying your guy wires into the ground. You'll While the paint on the mast is drying (two need first three spots 120 degrees apart (ap­ coats take severa l days you know) it's a good proximately) and at a minimum of 7 % feet time to prepare the base mounting. This isn't from the center of the mast base. 10 feet is too bad and involves only digging a hole in better, bu t 7 % will do very well. \Vith a piece t he ground abou t a foot squa r e and approxi­ of str ing, centered on the mast base, you can mately ten inches deep. Make a little form of scr ibe a circle on t he ground and determine scr a p lumber if you're meticulous, let it pro­ your anchor points. Maybe you have a con­ trude about two inches above the ground level. venient tree a st ump or a building which will • • F ill the thing with concret e; you can get ser ve, in the a pproxima te area. If so, use It, "ready-mix" sa nd, gravel and cemen t in a If not, you have sever al choices for guy convenient bag a t your lumber yard). Follow a nchors.You can buy conventional, drive-in cr the consistency instructions on the sack a nd screw-in types of pole line a nchors from your you'll come out all right. After it sets up about power compa ny ; t hey won't be cheap how­ half hard, bevel t he top fou r edges if you like ever . You can dig a hole about two feet deep for a more professional job. At the same time, and t hree feet squa re, make a cross of a couple scoop a circular depressi on in the center of the of 30" 2" x 4" timbers and lay them in after top of the concrete base to a ct as a 'socket' for wrapping some stub lengths of guy wire t he base insulator to be next described. Use a around them to which you can tie your guy tr-owel for t his operat ion or you can use the wires above ground. Or, you can dig holes insulator itself in 'postal' fashion to achieve about a foot squa re and 18" deep, set a six this. Now you ca n leave the base alone while or 8 inch eyebolt (galva nized of course) in the it sets up (about 24 hours) . The base insulator a pproximate center , pour the hole full of con­ should next be procured a nd mounted on the crete mix and wait for it to set. Any of these mast. See the 'outside line construction f ore­ methods a re good ' you choose the one which " man' of your local power or telephone com­ you lik e best. Ev.en six foot lengths o.f 1 pany and show him Fig. 2. He will immediately pipe, driven at about a 30 degree angle, WIll do r ecognize "L" and "0" as a sta nda rd cross­ the trick. arm insulator ("L") and wooden mounting And with all of the above done, you need pin ("n"). wheedle, cajole or buy such a merel; r aise your mast, t ie on the feed-line ~ s combination from him ... it will cost you little. shown in Fig. 2 or raise your wire antenna 10 The insulator "L" can be either glazed por­ place, or both, 'and you're "on the a ir" with celain or of blue/green bottle glass as used by eit her a wire antenna or a vertical or both at the phone companies. E ither is more than ade­ will, as you choose! Lay back now and take quate electrically and mechanically. it easy; this is a mast which will last you a The end of t he wooden pin opposite the l-o-n-g 1-o-n-g ttme. Il 73 threads will be too small for your 2" mast. Build it up to the 2" diameter required w ith "' shor t wood strips (4). nailed with small brads ---to. to the pin itself. Balsa wood, usually available at most lumber yards, variety stor es and hobby ® ~ shops, will work well here. Get something about half an inch wide and of a suitable thickness to fill the gap when installed as shown in Fig. 2 at "B". A foot of this stock will be adequate. 1\I ount t he insulator and it's \ pin as in Fig. 3 and you've got a complete , antenna mast a nd vertica l antenna r eady for ~ erection when the paint dries! .... • " ® ,/ \ Your Co mplf'tf'd Antf'nna Sup!tort :\Iast/Vf'rtit":al Radiator • [ Should Look Like This! / \ A- Horiwntal w ire ant enn a pole _ line cross - arm In; ! , . , I , D-In sula tor lor " A" su la tor •• G--Down -haul rope or ea- G-Concrete base; about 1 ble ( use a sash weight cubic loot a t lower- end or a nchor H - Co-axia l cable feeder to a ch'at or E'ye-bolt (RG8/U or RG58/ U) near base ol m ast ) I-Ground rod ( 5 or 6 loot , D-Guy wire (.:t14 g81­ copper clad steel wit h va n teed iron) clamp) E--A irplllne t ype o l "(COOlie­ J -Porcelain i n s u lated ee e " stra in Insula tor scr ew-eye insulator F-Glazed p o r c elain or K-Gu)' w ire a nchor 'bottle-elass' pett i c o at

73 MAGAZIN E • 39 JANUARY 1961 The Diligent Detector 7] Stoff

O far as most of us are concerned, the clarify the approach used in this review, you S detector is the "forgotten man" in a com­ know that an ordinary A~l signal may be visu­ munications receiver. Ultra-simple circuitry, alized in either of tw o ways: It may be con­ tried and true over the years, tends to make sidered to be a single, steady carrier wave us think of the detector (when we bother varying in amplitude, or it may be thou gh t to think about it at all ) as one of the most of as an un varying carrier accompanied by nearly perfected parts of the set. sidebands of varying strength which are lat er The general impression that d etectors have mixed wi th the carrier to produce sound. little room for improvement isn't correct. F or \Vhile the second visualization is more cor­ a few cents worth of parts and a few minutes rect in the mathematical and physical sense, time, you can reduce your set's detector dis­ there is no measurable difference between the tortion to a fraction of its previous value. two. To avoid complicating this article with This will do a near-miraculous job of clean­ exotic mathematics, the first (and older ) visu­ ing up formerly-muddy signals whose only alization has been used in explaining diode­ actual fault was 100 percent modulation, and detector action. may even restore broken friendships if bad Sinco the most common detector in use signal reports caused th e breach! today is the diod e, let's look at it first. Most You call take your choice of a number of diode detector circuits are similar to that circuits to accomplish this end, thanks to the shown in Fig. 1. You may find a crystal diode audio fraternity which devotes much of its instead of the tube in some receivers, but the time to reduction of distortion. Some are principles of operation remain unchanged. nearly as simple as the conventional detector, Similarity between this circuit and an ordi­ while others involve addition of one or more nary half-wave power supply (less filter ) is tubes to the set. evident. However, the two circuits differ Each of these circuits has its own set of d rastically in several important operational advantages and disadvantages, making the details. choice a bit more complicated than one of In a power supply, the design factors are mere time and complexity. The purpose of chosen so that current will flow over as much this article is to list these circuits, together of the cycle as possible without flowing dur­ with their pros and cons, to make it easy for ing the reverse half-cycle. This reduces ripple you to pick the one best suited to your own voltage in the output to a minimum. needs. In the detector, however, the objective is Before going into the newer and more­ to make current flow through the diode in a sophisticated detector circuits, a brief review series of extremely short pulses. This is ac­ of the conventional detector is in order. To complished by making the resistance of RI very large compared to the diode's forward Fig. I. This basic circuit, or slight vari,~ltions of resistance, and by making the applied signal it, is the seeend-detectee in use in nearly every voltage as large as possible without running radio receiver on the market today. Except for into overload. the filter, the circuit is identical to a half-wave power supply but operates in a completely dif. Under these conditions, CI is charged by ferent fashion. the short pulses, and if the time consta nt is properly chosen the ca pacitor voltage will rise almost to the peak value of the applied signal. The voltage will vary in a linear manner with the strength of the applied signal as measured at the peak. For this reason the circuit is known to engineers as a "peak-linear" detector. ., Note that the voltage impressed on CI will follow the signal modulation envelope only if .. the tube voltage drop is negligible compared OUTPUT to applied voltage. At low signal levels, every rectifier becomes a "sq uare-law" device whose

40 • 73 MAGAZINE JANUARY 1961 voltage output varies with the sq ua re of input neers as "clipping" and as «differential dis­ voltage rather than varying linearly. Square­ tortion," is the major factor limitin g acceptable law detectors produce excessive distortion of modulation percentage. Distortion in conven­ A ~ I signals, but are useful as mixers. tional circuits remains under 5 percent at Under normal conditions, the output of an moderate modulation levels, but rises rapidly ordinary diode detector contains about 5 per­ to 12 to 20 percent when modulation depth cent harmonic distortion. \Vhile signals are approaches 100 percent. perfectly readable with this amount of dis­ T he third factor introducing distortion is tortion, reception can become extremely tiring the He lime constant of the detector load ( HI to the ea rs-as anyone who has ever operated and C I in Fig. 1). ]f the time constant is in a contest knows. too long, "bottoming" will occur on negative In addition to introducing distortion, the half-cycles of the inco ming signal, prod uc­ peak-linear detector plays another sneaky ing a raspy and most objectiona ble sound. ]f trick 011 the signal-it cuts down the effective it is too short, detector output will be low and modulation percentage. rf ripple will be too high.T his is not usually T his can happen because the if amplifier a problem, since design values found in most feeding the detector has very poor voltage sets represent a highly accepta ble compromise regulation. Output of the if transformer, with between output level and distortion. the same signal applied to the amplifier, is W ith this background established, we're considerably less under load than it is with ready to examine some low-distortion circuits no load- and the diode detector represents a and to compare them to existing detectors in very appreciable load. your receiver. W hat's more, th is load varies with strength One of the simplest of the low-distortion of the applied signal since the diode's im­ circuits is the "diode integrator" described a pedance will vary with voltage applied. This couple of years ago by Leonard Geisler. It's means that the if amplifie r is under a heavier shown in Fig. 2. load for the sidebands of a signal than it is for the carrier. and the ratio of sideband TO IF' power to carrier power as measured at the PLATE detector is reduced. Bad as this sou nds, it's actually no loss­ since a peak.linear detector is not capable of reprod ucing a 100 percent modulated sig­ TO 8_ nal without severe distortion. In one typical '""'0 case, breakup of the signal became objection­ ., OUT able at 75 percent modulation. Other authori­ ca lOOK ties claim the effect is severe at 70 percent. .1 By red ucing effective modulation percentage. the diode makes itself able to handle a more­ deeply-modulated signal than could otherwise be accommodated. Fig. 2. The diode inteqrator, sometimes called Distortion in a peak-linear detector is a peek-to-peek d etector, provides a virtually epen-cireult load to the il t ransformer sec' caused by three major factors. One-curvature ondary. All d istortion resulting fr om assym etri. of diode characteristics-is outside the control cal transformer loading is thereby eliminated, of the designer or the set owner. The other and detector efficiency is increased . two ca n be controlled to some degree, but the control always represents a compromise. Instead of being patterned after a half­ W henever the de component of the signal wave rectifi er, this circuit is an adapta tion and the ac component meet different load of the fu ll-wave voltage doubler. Since it is lines, distortion is sure to result. This situa­ a ful l-wave device, it utilizes both halves of tion occurs if AVC is derived from the de­ the input-signal cycle rather than only one, tector. if an S-meter is connected to the with resulting increase in efficiency. detector circuit, if an automatic noise limiter The reduction in distortion is brou ght about is incorporated, or if the detector feeds an by the fact that one of the two diodes is con­ audio amplifier. The Jast condition is neces­ ducting at all times. and both diodes never sary if you're going to hear anything out of conduct simultaneously. \ Vith both C I and C2 the setl set at the same value, the if transformer al­ This condition, known va riously to engi- ways sees a capacitive load- and under this

JANUARY 1961 73 MAGAZINE • 41 hias to the AVe line and then to clamp the -,Le' line to ground . I'" 100 The result is that the AVC line must over­ come the positive bias to become effect ive, ot ., hut can never go positive itself. The voltage­ PUlE ~!II! ~ " . C!JL d ivider circuitry provides a constant load for ,. ,r r . ,. ,.00< ""'" -aeo the AVC diode, preventing interaction with "' e'J( the detector diode coupled to the same trans­ ., '00" ~ ~ former and thus eliminating differential dis­ eoo« "UOIO OUT ., tortion due to the AVC action. m, The advantage of the circuit is its reduction '- ., of d istortion, coupled with DAve provision. AVe lNEG Major disadvantage is the requirement for , ;~ . . •• ., added components. A secondary disadvantage '70' '00' is the requirement for "cut-and-try" tailoring l'-e- . ~ '"' - of component values in the AVC circuitry. •• Since much of the distortion in a peak­ - 4.1"'EG linear detector is caused by interaction with associated circuits, use of some sort of isola­ Fig. 3. Most complex of the detector circuits shown here is the "sinki ng di ode" arrangement tion device appears to be a natural to elimi­ whic h includes delayed Ave a nd reduces dis. nate the distortion. One of the simplest and tortion. Crystal di odes ca n be substit ute d for most popular such devices is the cathode oI and 02, but 03 must be a tube to achieve follower. extremely high reve rse resistance. T wo circuits combining the diode detector and the cathode follower have been published, condition, the capacitance can be trimmed out and excellent results are report ed with each. by retuming the if transformer to resonance. The simpler of the two was developed by T his results in an effective load of nothing W. T. Selsted ami B. H. Smith in the Hadia­ at all; at one fell swoop you have eliminated tion Laboratorv of the University of Cali­ modulation cutting and have more than fornia, and appears in Langfcrd-Smuh's writ­ doubled the efficiency of the detector. ings. In it, the cathode follower follows the Advantages of this circuit are the reduction detector (see Fig:. 4 ) but precedes the load of distortion and the removal of loading from capacitor and filter components. the outp ut if transfor mer. Claimed distortion reduction is from 12 per­ It s major disadvantage is the high outp ut cent to less than 1 percent at total modula­ produced; in new-design eq uipment this is no tion. This is achieved because the isolation handicap, but when you modify existing equip­ presents an essentially resistive load to the men t the 35-volt peak-to-peak audio which detector, completely eliminating all causes of co mes out of the integrator and the 100 volts distortion except diode characteristic curva­ of AVC both prove somewhat unhandy to ture. Curavturc effects are minimized by keep- work with. \Vhile voltage dividers can be used to trim them back to more conventional values, the d ividers will then introduce fre­ Fig. 4. Leu th an I percent distortion a t 100 quency d istortion and differential loading cf­ percent modulation is ihe claimed performance Iects which may cancel out the advantages of of this cathode.follower plus diode detector circuit. Shunt impedance is eliminated from the circuit. the diode load (R1) by the direct-coupled Another low-distortion circuit is the "sinking cathode follower. diode" arrangement described b y Langford­ Smith and shown in Fig. 3. This circuit elimi­ TOIF nates differential distortion and also produces PLATE 12AX7.ETC. delayed AVe, at the cost of several additional components. It has been applied in at least '---1------one receiver-updating technique, and excel­ ., lent results have been reported. This circuit is identical to the peak-linear "'" . 02,,+_ + AWO circuit insofar as the detector itself is con­ 15K < OUT cerned. The only departure from conventional ".''--- --i techniques is use of a voltage divider and a clamping d iode ( 03) to first apply a positive

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JANUA RY 1961 73 MAGAZINE • 43 •

ing applied signal voltage high-greater than stage and three other components to the re­ 10 volts in most receivers. ceiver. However, it should be a natural for Major disadvantage of the circuit is its re­ inclusion in a homebrew receiver. q uirement for an added tube.However, Another ap proach to detection, basicall y should your receiver use a GALS as detector, different from the peak-linear diode circuit, it can be replaced with a 12AX7 w ith little is the "infinite-impedance" detector. Fre­ d ifficulty. The 611 6 can be replaced with a quently used In hi-f gear, it is seldo m seen 6SL7. in communications receivers because it makes There is no hurd-and-Fast rule that the iso­ no provision for Ave voltage. lation must be between the detector and its load. Similar advantages may be gained by isolating the detector from the if transformer _ISO as described bv Snreda. In this circuit ( Fig. 5 ), two major advan­ ~ ~@~6 AV 6 ' II Z IZAX7 tages appear. Loading of the output if trans­ ~11€ --- for mer is subs tantia lly reduced, since it feeds ;;~ gil only the high -impedance input of the cath­ • jll,-.., ,-+-.... AUOlO OUT ode follower. Differential distortion is also CI Rl slashed by an appreciable amount, since the .000 '" detector load resistor ( R2) is so much lower than any ussociuted shunt impedance. This means that any variation of shunt impedance with frequency or modulation depth becomes Fig. 6. The lnflnlte-lmpedence detector ep­ only a minute fraction of the impedance of H2. pears similar to a cathode-follower amplifier but operates differently. It reduces distortion a nd increases selectivity, but can be e verleed­ . 1SO -~ ed more easily than the conventional di ode circuit. 6C4.ETC. ~ II --- A typical infi nite-impedance detector is IF shown in Fig. 6. You can see that it appears II AUDIO II identical to a normal cathode follower type OUT ~ amplifier-and so far as the circuit goes, it as C2 ea is identical. The difference lies in the tube's 10 ' ,0041 operating point. "" S6MEG " W hile circuit constants in the cathode Icl­ lower are chosen so that the tube acts in a ",c linear manner, an infi nite-impedance detector C3 033 is biased almost to the cutoff point. This is T accomplished by the extremely large cathode resistor, Rl. Fig. 5. This cat hode-fo llower detector c irc uit With no signal, little plate current fl ows provides both a udio a nrt Ave fr om a single and the voltage drop across Rl is small and diode. It e liminates diffe rential distortion by steady. When an rf signal is applied, more keeping diode loa d resist an ce R2 at a low va lue so th at a ll shunting impedances will have plate current £l ows at positive peaks, increas­ minimum effe ct ing voltage drop across HI. T he voltage across H1 reproduces the signal's modulation en­ Use of the lew-valued load resistor requires velope in the same manner that the envelope that a high-conductance crystal diode be used is reproduced in a peak-linear diode detector. as detector. ]f a tube is employed, its for­ Sin ce the tube is operated in cathode-fol­ ward resistance will be an appreciable frac­ lower configuration with a large amount of tion of the load resistance and distortion will feedback, its input impedance is high. As a skyrocket. result, the if transformer is not heavily loaded No figures for distortion red uction have and selectivity is increased. The large amount been obtained for this circuit. However, it of feedback prevents overload effects until the appears that its performance should be com­ grid is driven far into the positive region, at parable to that of the d iode integrator. which time d istortion suddenly becomes ex­ Major disadvantage of the circuit is its treme. Since this doesn't happen until input complexity, requiring addition of one triode nears 50 volts, its effect is usually absent.

44 • 13 MAGAZINE JANUARY 19b1 A PRE-ENGINEERED HAM EQUIPMENT CENTER WITH BUILT-IN POWER & o COMMUNICATION FACILITIES

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Additional accessories w ill be available soon-watch for advertisement. Specs . a nd prices , ubiect to chan9. w ithout notice.

JANUARY 19b 1 73 MAGAZINE • 45 •

Distortion level of the typical infinite-im­ ability. pedance detector at 100 percent modulation is The superrcgcn has other advantages be­ in the neighborhood of 3 percent. This is not sides extreme amplification. It automatically so low as some of the more sophisticated diode limits its own output, making noise limiters circuits, but appreciahly lower than the 10 and AVC circuitry unnecessary. to 15 percent prod uced by the conventional However, in most applications its disad­ diode. vantages outweigh these advanta ges. The su­ Aside from circuit complexity, the major perregeu produces extreme noise output in disadvantage of this detector is that it makes absence of signal (the hiss mentioned before ). no provision for AVC takeoff. \Vith the re­ It radiates an interfering sign al, not only on ceivers using amplified AVC such as the the frequency to which it is tuned but at all Super-Pro and the SX-28, this poses no integral multiples of its quench or squegging problem. frequency for several megacycles in either di­ The only other A ~ I detector still in any­ rection. Its sensitivity is low despite the gain thing like wide usc is the superregenerativc because of the high noise output. And finally, circuit, developed by ~I aj . Armstrong. Hele­ its distortion is high. The superregen is defi ­ gated to the UHF hands before World War nitely not a low-distortion detector. II, it W ..L<; bronght hack fro m obscurity for \Vith a couple of modifications, though, it usc in Class D Citizens Band equipment and, can fill a major need as the second detector with some modificat ions, can find a penna­ in mobile sets design ed for VHF use. In this nent place in ham eq uipment. application, its amplitude limiting and great Too many superregen circuits exist for us gain become major advantages. Use of super­ to list them all here. One easily-handled het configuration for the receiver eliminates version is shown in Fig. 7. Note its strong re­ the low sensitivity, interfering radiation, and semblance to a grounded-cathode Hartley broad-tuning characteristics of the superregcn oscillator.As a matter of fact, the superregen used alone. is an oscillator, with its grid-circuit tim e con­ Care must he taken to shield the detector stant chosen to produce "squeggmg" at a completely. Otherwise, signals at the if will supersonic rate. The ear doesn't hear the leak through and he detected because of the oscillation or the squeggiug, and the nearly­ great gain. The if frequency to be used must infinite amplification produced when the cir­ also he chosen carefully. Quench or sq ueggtng cuit is oscillating makes it possible to hear Frequen cy should be approximately 1/1000 even the weakest signals. the signal frequency for best results, but in One major cha racteristic of the suporrcgen no case should it be in the audio range (or is its characteristic hiss. At one time, they even lower than twice the highest audio fre­ were known as "hiss-boxes." This hiss is ac­ quency desired in incoming signals) . This tually the noise produced by random move­ means that the if chosen should not be lower ment of electrons in the coil and in the than 10 rnc and can never be lower than 5 antenna- indicative of its great amplification me if good results are to be obtained. The circuit shown in Fig. 7 is designed for Fig. 7. This superrelJene rll tive detector for use in VHF mobile receivers co mbines AVe. noise use with an if of 17 me. It can be used with­ rejection . li nd extreme amplificlltion. R2 con ­ out cha nge through the range from 10 me trols reqen eration lind R4 is the audio gain upward. Should you desire to cha nge the ccntc ], The trllnsformer second ary must be quench frequency, the components which de­ centerta pped. termine it are HI and C3...... , Automatic Volume Control lOOK ., OUT While Ave circuits are rightfully a subject 112 6U8 ",,, unto themselves, they are so closely related to detectors in so many ways that they will be '"OM Cr'M~l.:i?'::li~-- If __-+ C2 IN IF -- treated briefl y here. The basic Ave circuit is identical to the " 0 ' peak-linear diode detector shown in Fig. I, 820K except that the AVC output line includes a low-pass H-C filter to eliminate all audio , _"0 components and leave only the de voltage de­ veloped by the incoming carrier. The time constants of this filter determine

4b • 73 MAGAZINE A WORLD OF VALUES

The Transceiver Buy Of A Lifetime! MODULATION TRANSFORMER 12 15 MC TRANSMITTER & RECEIVER Push pull 807 's to 829 fina l. H erme tically Consists of superhet rcvr a nd p ulse xmft for c per­ sealed ...... $3.95 ation o n 950-1330mc band. FILTER CONDENSER 1 TRANSMITTER: 2 12 watt output CWo Preq.: High volta ge filt er co ndenser. 4mfd 3000 vo lt 1215·1233mc. oil $3.45 REC EIVER, 100 DBM 925. 1330mc, 90DBM 23 00. 2465mc. Superhet. FILTER CHOKE CAVITY: Contains loc al csc., xmtr, p ulse e sc. Ittl 6 henry, 400 rn a. 600 o hms. C ollins se a led. 10kv mixer, 1-2C42,1 -2C46 tubes. Veeder counter. insulation $3.95 C ompletely wired. COAX SWITCH 60 MC IF STRIP 110 vee coax switch $3.95 Conhins a.6AKS l·bA LS tubes. Completely RECEIVER wired. Rl·I 037 & Rl.I039 rel ay inc lud ed. Receiver practically rea dy to go as is. Transmitter APR·4 Re ce i· e r , Like new $49.50 easily conve rted from pulse to CWo Easy-to. C urly C ords 49c follow, complete conversion instructions by WbMMU. 121Smc reco rd holder supplied fr ee of charge. COMPLETE AS ABOVE only $7.95 CAVITY AS ABOVE Com plete 4.95 IF STRIP AS ABOVE with tubes ...... 3.95 SIGNAL GENERATOR Hidok crystal controlled signclll gen era tor, 90 to 1600 kc, 1.6 t o I 44mc. A re al spe cial at on ly $21.95 APX-6 C ompl ete A PX·6 $ 10.95 See QST for Sept. CONDENSER 200-432 me CAVITY I·GE C o nd enser. 25 ,000 volts ...... $6.95 A simple and efficie nt way to get o n 432mc. Use t his unit as a tripler a nd d rive it with your 2C39 SOCKET ASSEMBLY C ommunicator or ot her 2 meter rig. Uses push­ Complete socket assembly fo r pair of 2C39's pull 2C39's in grounded g rid . C omplete conver­ includes g rid by-pass condensers a nd dc con­ sion info in Dec. issue W RA. nedions. 160 waHs input from 160 to 431mc. C om plete wit h tubes .. $12.95 l ess t ubes $4.00 C om plete less tubes . . 7.95 HEADPHONE LINE STRETCHER Aircraft type with ear pa ds ...... $3.95 Improve your loading, lower your SWRI Sil ver FILAMENT TRANSFORMER plated line stretcher Only 95e Fine for bridge reettfler, Will handle four 866's VIBRATOR in bridge circuit. Two 2112 volt 7 a mp windings, b.volt heavy duty vibrator dual contacts ... .99 one 2112 volt 14 amp winding. Impregnated against moisture $2.95 PHOTO FLASHER PLATE TRANSFORMER Sylvania photo fl ashe r complete with t ube $19.95 110, 220, or 440 volt primary. 400-0.400 volt 735 MIKE rna secondary. Impre g na ted ...... $3.75 C a rbon push mike $ 1.49

GLOBE ELECTRONICS 3103 PICO BLVD . SANTA MONICA, CALIF. EXmon. ].7206 & ].7207 Open 9 a .m. t o 5:30 p.m. weekdays

JANUARY 1961 73 MAGAZINE • 47 how rapidly the AVC will act, as well as the \ Vhen receiving C\V or SSB. neither con­ speed with which it will release after the sig­ ventional nor delayed AVe is in itself accept­ nal stops. F or communications use w ith able. Means must be found to apply Ave normal A ~ l signals, an overall time constant quickly. while retaining it even with no signal of about 0.2 second (for both attack and re­ incoming. Such circuits are known generally lease ) is optimum. Shorter time constants as "hang AVC" circuits because the AVe volt­ enable the receiver to follow fading more nge hangs on for an instant after the signal rapidly, hut result in loss of bass from the is gone. These circuits, together with d etec­ audio.Longer time constants emphasize fad­ tors for C\V and SSB, must form the subject ing effects. However, in hi-fi tuners where for another article. 73 excellent audio response is more important than freedom from fading (since most recep­ BIBLIO GR A PIIY tion is local in nature), time constants for this circuit average one second. Eastman, Fundamentals of \'acuwn Tubes, Third A major disadvantage of the ordinary AVe Edition, pages ,564-576. Geisler, Rciu cenation for the AU Detector, Badia­ circuit is that it applies a control voltage for Electronics, October, 1959, page 58. weak signals as well as for large ones. In Greenleaf and Chandler, Low N oise A .\f Tuner other words, it cuts back the gain of the set Uses Triode Input. Audio, September, 1959, even when you want all the gain you can get. Page 19. Langford-Smith, Radiotron Designer's Handbook, {I To overcome this disadvantage, delayed AVC Fourth Edition, pages 1072-1086, also pages was developed. The delay refers to voltage, 326, 1108, and 1117. not to time. It means that no AVC is ap­ Sareda, Better Diode Detection, Radio-Electron­ plied to the set until signals are above a pre­ ics, Au gust, 19.56, page 103. Terman, Electronic and Radio Engineering, {I determined level. Past that point, AVC action Fourth Edition, pages 547-558. is normal. One of the best d elayed AVC cir­ Tschanncn, \V9L UO. The "Club Saver" 2-Meter cuits is the sinking diode arrangement,F ig. 3. Portal)[e, QST, October, 1957, page II. Another is included in a squelch circuit shown Vog-elgesang, Unique AM Tun er Im proves Audio ill "The Perfect Squelch" (73, December, Q uality, Radlo-Elcctronics, December, 1956, page 80. 1960, pg. 26 ). ·Avaihthle f rom Radio Bookahop . • SIX METER RECEIVER • TWO METER RECEIVER MODEL 505A-50-54mc MODel 506A-144-14Smc

Here's the ideal low-cost receiver to start your six or two meter station only 3 inches high

• Excellent sensitivity with stable superregenera tive detector • Built-in 110 volt AC power su pply • Fully transformer opera ted, no voltage doubler • Compa ct, fully enclosed in cabinet-only 3 in ches high • RF stage for increased sensitivity and isolation • Send-receive switch for muting receiver • Bo nd set capacitor for fu ll 4mc ba ndspread • Features stable operation a nd dependa bili ty Mod el 50 SA, 50 6 A, KIT, tomplete a s above : $29.95 • WIRED: $49.95 MOBILE OPERATORS: Model 505A, 506A are available with mobile power supply instead of AC supply at slight additional charge. Send for data on the complete line of NEil 2, 6 and JOmeter fi xed station, mobile, and portable receivers, tra nsmitters and transceivers.

St;t<; \ '0 [;8 U K\LEK. OK OK lfER } ·R O:\I

THE NEIL COMPANY 1 1336 Calkins Rd • • SAker 5-6170' Pittsford, N. Y.

48 • 73 MAGAZINE JANUARY 1961 Ham Headlines

If ham radio make's flu: II c1I's/, a/,c r s in y our tm,'ll pI{'(ISt' send a d ipp ing to .\lan -in Li(>to)l VEJDQX. 3 1 1 Rose­ lIIary R oad, Toronto 10. Ontario, COlw do. .l/an-i" runs tile 73 XN.CS S rrn"c(' , /I mOlltl), publication $('11 ' to all editors of cllfb bulJetins. Ill' ~1;lI diacst the mo,st importollt stories that ore submitted eoch month f or u.s to prillt in 73. EVANS OFFERS lIam Station in 8 0mh Sh..Itej- COMPLETE SERVICE A ham Il l a t io n , oper-ntin g- on a ll a m a teur banda from Six to F.ighty meters, ha ll been inst a lled in t he enf'e­ • To HAMS · -• By HAMS ter-ia, wh ich doubles lUI a bomb s hel te r, of the C fevela nd ( 12 lice n se d employees) T w ist Dr ill Com pany, There are both indoor and out. door a ntennas, j ust in case. Call letters a re K8UFN . • EOUIPMENT a nd COMPON EN TS (ClN/dona P lain D eater, Clet-dalld. Oll i{) • . • from Parillo (Ho m - Ele ct ronic· Electrical) Radio Ollb). • TRADE·INS Ion new o r used units) II a ms and Uuctar Aid Stril:ken lIun tt'r • TIME PAYMENTS W 5FFX, W. C. London , at a ranch in Folsom N ew (fle xi ble . finan ced ourselves) Mexico put II phone putch t h roug-h W6MLZ, Ray Meye rs, to a doctor in t he Sa n Gabriel H os pit al. The doctor • ENGIN EERING DEPARTMENT prescribed emer srencv t r ea t me n t for II hu nt er- w ho ha d (backing a ll equipment sales) been str-ic ken wit h H h ea r t attack a t the isolated ranch. • REC ONDITI ONED EQ UIPMEN T Another a m a teur alerted a n a mbulance which rus hed La rg e st invento ry in the Northeast oxyge n to the sce n e, The new Mexico Hig h wa y Patrol la ter not i fi ed W6~fL Z that t he hunter had arrived a t • EXP ERIENCE --• 26 ye a rs as: the hos p tta l in Folsom a nd was o ut of da ng e r . (Los All' grla Timl'S) , "YOUR FRIENDLY SUPPLIER"

Tower Legislation The Menlo P a r k City Dou n cil has decided to make II blanket ruling a bout ham r ad io tower s. The iss ue was brought to a head by t he 70 foot tower of W illiam O r r W 6SAI w hich t he Cou ncil or-der-ed h im to ta ke down. Orr disputed the rulinK a nd refuged to take it down. A second tower was rece ntly discovered by the City P lann er, this o n e o nly 50 fe-et hhth. S ince the city h eig ht li mit is 35 feet this wag added to t he O r r tower d if­ fi culty a nd 1\ sing le com prehens ive r u ling s hou ld r es u lt. ( Daily Palo Alto T im('s, Palo A lt o, Califortlia) , VESTOTOWER Survives 156 mph Letters HURRICANE "DONNA"

n ea r P orsche P usher, Ve sta' s fam ou s H ullo There I J us t g ra bbed a copy of u r ne w m ugu­ "Hurricane-Proof" aine today (la s t copy of the October lseue ) w hic h m ade Construction is me pretty ha ppy. Dunno why I m ade tha t t rip to the the Rea son ! local Clip & Gip joint- but m aybe t hat "One S te p Be­ yo nd" p rog ram knows what it's talking a bou t. Anyhoo, I'm au r'e Klad that the ex-vEditor o f a lead­ NO GUY WIRES ing t ech n ical m ag a zine in the elect ronics fi eld ," to Quote a s ports car m ag azine which once pub li"hed a n article EASY TO ERECT by some g uy named G reen on Rally (e) inK, is back in t he business asnin. " X X" los t m e a bo ut t he aame time Step-by-step that it lost YOU (well maybe 2-3 minute later) , and instru ctions given! I've been ho ping you would r eturn. I renlize tha t t he Can be taken down opin ion of II teenager w ho can 't even a lford $3 for a and moved easily! 8u b!lC r ip t io n m a y not cou n t fo r too much, but I s u re like t he n ew "73" and you can be darn BUr l,' that my HOT DIP next $3 is headed directly to you ca ts. GALVANIZED Speaking- of teenaeers, why don ' t you maybe devote some s pace to t his g rowing fa cet o f t he ham fratern ity 1 to la st a lifetim e! A Qu ick g lance at t he loca l h igh schools' regional Sci­ ence Fa ir will show t hat we z ouns -un s h a ve a fa ir Prices start at a mou nt or kn ow -how . TH IS VEST O TOWER 2 10 (seventy 3's) ,. , Wm. Swo pe K7 H XP WITH STO OD HURRI CAN E Tacoma, W as hington " DONNA" IN FL OR IDA

OK H' m.• !,I/ t don't$ that S'/t'itch-bladl' alld start n.,.;t· ing. A lot of tcccnoarrs art' doing intt'rl'sting things if EASY PA'I'MUIl PLAN! VESTO CO., INC. thr)"d only r,.,.ite 'r".. Ill'. I've s('en som e grl'rU lwme·brl'1.t' write for new, I 20th ond Cloy St. stuff built by tees ooers , bllt darned if I hat'l' been able fR EE literature. North Konlos City. Mo. to get 'I'm to arlid l'·is;e the stuff,

JANUARY 196 1 73 MAGAZINE • 49 •

••••••••••••••••••••••••• ••••••• (6 end 2 from p"ge I I) ~ KEEP CANDEE HANDEE! t FAMOUS Q 5'Eft III Construction T h" 11 the fantabu loJul 011." 190 -550 te. The ee- reller you',., been looklnt: ror at only • .• .•• • •••• ••• $9 .95 BC · 45.4 : 3-6 Me. 7.95 BC· 455 : 6-9. 1 xre...... • .•. .• .• ..•• .•• .•• 7.95 The converters are built on a 3"x7" piece MO·T MODU LATOR : l';ll~d lll . •...... 3.95 of copper sheet with the edges bent 90° A TRIO OF HE AD SET BAR GAINSI H5 · 23 : III Imlledlnrll. Leat her COI' ""e!! headb and. for strength. If copper is not available try Urand nee. Grn t buy. Only ••• • ••• • ••••••••• • $4.9:1 H5.33 : !..ow lmped&n{lI. Le l lh~ ecreeed head· using printed circuit board as a chassis rna­ band. Brand nt'\1\'. A. ~ . J . Candee Special .... . 5.95 HI Fi H_ dset : 15.000 eyclH! Brand n_ with terial, without etching. Drill all holes first; chamoll ewbllXll. U', terrlfte l Onl,. •••• • •• ••••• 1.95 CO ·307A H" n t Eat_ion Cord : Brand new. then mount the Nuvistor sockets, filing the Appnllrlmltely .5 ft. IMic th. Only ...... 49 necessary slots in the ~" mounting holes. Next " PH -' Filii TRAN SC EIVE R 420-460 :\fl'. Comp l. wUh tubes. Eac. Ea. .•...... • $2.95 mount the shields by soldering to the chassis. Apprux. hhp. 1\"1. per uni t 25 Ibl. •.•. •• .• .•TW O lor 5.00 YOU GOT IT l WE WANT IT l LE T'S DE AL ' We're payi ng top $U for HltC-S; PIlC-6. -S. -9, - 10 : , GN· roIlA : All etecceoote test equtp. ! , J. '+ +'+ t • , •• +t i+ AP X·6 TRANSPOND ER • +++ , "+++.., A ml lllet warehouse of pan' l B lowen . three v eeder­ +.~ ... , + + Root count"'". I . F. strIps. cavity. over 30 tubes. ere. + + , + ".. + Ind udM 3 E29 tuh. Good coed. ASTEAL AT O:SLY , (2 to!' $19.00) •.• •• • •• •• ••. •. .. •. .••••. .. .• • ..•• .• $9.95 ...... , .., .., + + + ++ + +0+ + ++ + + + R·-4A /ARR·Z RECEIVER , , 234-258 1ofe. 11 tubee, t.:H lo.. tunable reeetrer, See i i i i , " AUI .l59 C.Q. :l1.,u lne rOlf eotlvenlon. Exc-ellent eced. •+ + two tot" $5.00. Eadl $2.95 + .. ~ ••10 .elO + 1.208 FMS IGNAL GENERATOR + + , + + FreQ . r&n(et : 1.9-4.5 Me. and llt-4:j :Ill.'. Frequency , d eYl atloo m&1 be adJulted 0.5 kc. for 1.9-4 .5 Me. and • 0-50 lie. each sldll ror the 19· 45 Me. band. ' v Uh output mete r and IPuklll". 115v 60 cydea or 12 Y!>c 2M ....J-.6M Input. Excellent eonc tttcn. .. . •••••• •• •• •••.. . ..• .. $49.95 j I. • A ll I'llnu FOB IJllrbnnk, Ca lil., .ub}"ct fa prIor In le. " DRILL U~""",Rlt[O HOI.£S .12 MTL' .020 (»t .on COfOp£R In Ca llI . n d d .,%. M in_ a rder '3.95. TAP .4'5 HOI.£S 4-40 OR 1116' pR1NTl O CJllCUlT BOARD J. J. CANDEE CO. D.pl. M' 509 No. Victory Blvd., Burbank, Calif. The printed circuit board is considerably PhO M : Victoria 9-2411 easier to solder to than is the copper sheet. •••••••••••••••••••••••••••••••• Now mount all parts, and wire. The small color coded wires removed from 8-wire TV rotor cable are ideal for the hookup and the coil links, If only one converter is to be built CUT IT OUT! simply split the chassis layout down the center. Except for the extra hole for C9 the 6&2 Yes, cut ih is out and send it in ri ght ow~y · .. we need it vesterdev.The problem is this: layouts are identical. we need some Fects end figures to help snow I hope some of you p's and 1', will build ~dvertisers . The main figure we need is one this converter and listen for K8ERV on 21 which wil l give them an ideo of how mll ny 73 73 reeders do not cerefullv reed other hem meqerines so t hey can see why, t hough t hey mev advertise elsewhere, they mus t elsa use th e peqes of 73 t o eporoech our elusive reed­ e rs.If you don't li ke to chop up your meqe­ New Product zine then send us e pcstce rd. IMPORTANT: send something . ••••••••••••••••••••••••• ••• Inlernalional Crystal Calalog Questionnaire If you look cereiullv in the smaller type in t he In­ In oddition to 73 I corefully reed the following temefionel Crvstel eds you will notice t htl t e ceteloq he m rneqezines __-:-__~~__--::-:-_-:­ is listed as being evaileble. Their new 196 1 mod el · .. (Oh, while you're sending something in is just off t he presses end it is 0 d er b. Thecreticellv you mig ht es well vote on t he erflcles} . you IH e supposed t o be interested in home brew if - Nuvistor Converters - Suction or W hoosh you read thi s meqezlne. t hus you e utcmeflcellv be­ -Down With Dri ft -Xstr Comm. Receiver come 0 first cless cendidete for t his home b rew ers --6N2 Complete -Vert icol peredlse. To be blunt : send immedletelv for this - 1296 mc -A-M Detectors ceteloq end join the rest of us in hungrily ogling -Goblin Petrel - T·1 7 Switch peqe eiter peqe of goodies. They heve dozens of -lost in Il Tunnel -c-Propeqetlon Chert circuit kits in there, both with t ubes end t ransistors. -8 me Conversion -Spot Freq. VHF Nets You cen build almost enything you wont with these -Trenslstor Freq. Std. -See-Sow Bleeder bes!c kits. If this cetelcq doesn't get you 011 excited then t urn in your hom t icket end subscription to 73, [Pleese list order of your preference . . • your Novice license htl s expired . lntemeflonel C rystel 1·2·3. etc.] Menufecturlnq Ccrn penv, 18 North Lee, Oklehcme City, Oklehome.

so • 73 MAGAZINE JANUARY 1961 A Versatile CITIZEN BAND TfXA$ . CLASS " D" CRYSTALS All '22 Frequencie s in Stock """ 3rtl overtone. .005% tolerance-e-tc meet 1111 .1<' C C requirements. H ermet t t- alty .ellied from Surp us IIC6/U holders. 'AI" pin Switch sjladng- .OJO pins. (.U!l3 $2 95 pins available. aud 1St! per cr)·stal). • EACH

The following Class "0" Citizen Band fNlquonci es In stock HE worthy T-17 Microphone has performed (frequencies listed in meIlMydos): 26.965, 2ti.97 5, 26.985, T 27.005. 27.015, 27.025, 27.035, 27.055, 27.1)65, 27.075, yeoma n military ser vice through one war 27.G8 5-, 21.105. 27.115, 27. 125, 27. 135, 27. 155, 27. 165, and a major " police action" and, in addition 27.175. 27.185. 27.205, 27.2 15. 27.225. .llald uJtl H)'stal sets for tnobe. uonset, CH I-Fone and lIalli­ has ser ved many thou sands of amateurs a s a ceauers Units .. . $5.00 pee set. Slll'eUy equipment make. rugged, high quality carbon microphone for •••••••••••••••••••••••••••••••• mobile and portable use. However, the best of : RADIO CONTROL CRY STALS IN HC6jU HOLDERS : equipment does give up the g host or is re­ • Rpodfy frequency, 'h" pin spacin&, pin diameter .05 • placed by newer and bet t er (?) gear. The T -17 • (.093 pin diameter. add 15t) $2.95 ea• • • FUNDAM ENTAL FREQ. SEA LED CRYSTALS • is no exception to this and repa irs of the • In HC6/ holders • • .I<:rom 1400 KC to 4000 KC .005% Tolerance ...... $4.95 ea. • models in which the carbon element is assem­ • F rom 4000 KC to 15.000 K C any fr equency • bled in the plastic case are difficult. • .005% Tolerance $3.50 ea. • • S EA LED O V ERTO N E C RYSTALS • • RUPlllled In metal HC6/U holders • • Pin spadng .486, diameter .050 • • 15 to 30 ~IC .005 Tolerance. • .• .•..•.• .•.•• ••.•..$3.85 ee • • 30 to 45 MC .005 'rcteran-e . .•.• . ..• ..•.•.•.••.•.$4.ll) et • 45 to 60 xrc .005 Tolerance $4.50 e": : ••••••• ••••••••••••••••••••••••• QUARTZ CRYSTALS FOR EVERY SERVICE All ery stals made from Grade "A" Imported Quartz.--ground and etched to exact f r e q II e n c I e e . Unwndltlonally &, ua rantoo

ASK YOUR P AR TS DEALER FOR T EX AS CRYSTALS See bIg r ed display .. . If he doesn't stock them, send ua hIs name and order dIrect from our Florida factory. NOW IE nglnee rIng samples and small quantities for proto­ types now made either at CliicallO or Ft. Myen Plant. 24 H our service I "Dismantled view of the T-17 switch showing IN C HICAGO. P HO NE GLadstone 3·3555 mounting details." RUS H YOUR ORDER TO OUR NEW PLANT Use coupon below for 1st Class sh ip ment. The photograph shows t he disassembled TEXAS CRYSTALS Dept. G·Il , lDOO CRYSTAL DR IVE, FORT MYERS, FLA. switch and the mounting cut out r equired. The For extra fast servtee, Phene W E 8·2100 other view shows the a ssembled swit ch mount­ • ed on a small con tr ol panel. The switch is easy •IATIACH TH IS COUPON TO YO UR ORDER FOR SHIPMENT I IV IA 1ST CLASS MAIL AT NO EXTRA COSTI to mount and where could you buy a better I TERMS: All items sub je ct t o prior sole and chonge of I switch for such applications as mobile VFO I price w ithout notice . All crystol o rd e rs must be accom- I " panied by check, cash or M.O. with PA YMENT IN fUL L. I spott ing ? I No COD's. Dept. G -II. . .. Pafenberg 1 ._------~

JANUARY 1961 73 MAGAZINE • 51 ALASKA mm. mm . m•••••• ARGE NTINA .m.a. a ••••• a •••••••••••• AUSTRALIA ••m... ..m. m••••• CANAL ZONE m...... • ••••••••••• ENGLAND GERMANY • ••••••••• ••• HAWAII • ••••••• •• INDIA •••••• • •• •••• •••••••11IIII. JAPAN MEXICO • ••• m•••••••••• PHILI PPINE'S ••• •• m PORTO RICO ••• m•••••••••a • SOUTH AFRICA •• ••••••• ..a•• U.S.S.R . •• . m•••••

ALASKA ARGENTINA .m• ••••• •••••• • ••••••• AUSTRALIA • •••••••••• CANAL ZONE ••••.am••••••••• • ••• ••••• ENGLAND • •••••••••• GERMANY • ••••••• ••• HAWAII • •••• •• INDIA • ••••••• JAPAN •• MEXICO • •• PHILIPPINE'S •••••••••• PORTO RICO •• •• SOUTH AFRICA • ••••••••••••••••••• m•• U.S.S.R . m.

ALASKA ARGENTINA •••••••••m•••••• • •••••• AU STRA LIA ••••mm• ••••• • •••••••••• • •••• 11IIIII. CANAL ZONE m••••••••• ENGLAND •••••• . m••• GERM ANY HAWA II • • •• INDI A •••••m• • ••• • •••••• JAPAN ••••m. MEXICO ••m• • • •• PHILIPPINE'S • ••••••••• PORTO RICO •••••mlllllll•••• • • •• SOUTH AFRICA m•••• • •••••••••••••••••m US.S .R. m••• • LEGEND ~ Propagation

Receive,... Transmitters. Mlerophonel. Met en. Headlell. Amplifier•• Gen. eratort. T ~ s t EQ ui llmcnt. T.l. phon. E«ulp. ment. Mot ol'$. Dyn.motors. P. ... r Suppli... Ant,nn' l. Cabl• • Tra nsformen . I IlYlrte,... Charts Etc.- Etc.

David A. Brown K21GY 60 Ne w Y o r~ Ave nue West Hempstea d. N. Y. 710k • • $29.95 GOO .Ki t k'::"7.!O,O-"' a nd a Sa ms 00 , TEM.6. $2.50 Ways to use your Ha m Test The bands listed are ~I U Fs and a higher Equipme nt." This book has 67 page s on how to u se the GOO. band will not work for the time period listed. Here i ~ my DEA L b oth of above $31.45 Pre-pa id to you Lower baud s will work, but not nearly as well. Da le W9NZJ/ ex W8GDE Times are G~ rr, not local time. Dalf.!'s Electronic S IlJJ I'I)' CO. These charts are to be used as a guide to ham 1125 Ea st MiC higan Street band openings for the month of January. MICHIGAN CITY , INDIANA 1961 to the various countries listed.I will be interested to hea r of your results in using these FABULOUS METER BUYS! charts and to know what other areas you 0-300 vee, 4" face $3.95 might wish included in future charts. 0· 100 ma., 2" or 3" round or square $2.95 " 'rile I .... Irr e bllll",i". O VE R 3.000 METERS IN STOCKI Add 50(' w ith order for handling & Shippi ng. 3529 Eost Co!ondo LR ELECTRONICS Pa s:ldeno, Colifornia Advanced Forecast: J anuary 1961 Good 1-3, 10.19, 23-31 risit COLUMBIA ELECTRONICS at the new store Fair 4-5, 8-9, 20, 22 4365 W. PICO BLVD. (nea r Cre'l$how) lOS ANGelES, CALIfORNIA LARGE STOCKO F ELECTRONICS COM PONENTS Bad 6-7, 21 HUGE SURPLUS DE PARTMENT COME AND GET IT! II you ran', rom.., .....iI..l

, E! - with - -"tk-

, . Send for (or, at your dist ributor), PL 77 Techni­ cal Specifications and Performance Bulletin de­ scribing 106 Anten nas from % t hrough 80 m eters including " BALUN "-FED ROTATABLE DI POLES. MONO. DUO. TRI. 4 -BAND AND "5PIRALRAY" ANTENNAS. ROTATOR/INDICATOR SYSTEMS. TOWERS. BROAD-BAND " BALUNS." ACCES­ SORIES AND " N ICE-TO-HAVE-AROUND- YOUR­ • SHACK" INFO.

For TOP·MAN·ON· C ommunic at ion an d T V Antennas THE-FREQUENCY results ••• SINC E In stall a Telrex antenna . . . dollar for 1921 rex LABORATORIES dollar better in eve ry way! Antenna systems from $6.95 t o $12,000.00 ASBURY PARK 40, NEW JERSEY, U.S.A.

JANUARY 1961 73 MAGAZINE • 53 Spot Frequency Operation Robert B. Kuehn WpHKF 1212 Bell ows St. Of VHF Nets St. Poul lb. Minn. o NE of the problems faced by users of com- me crystal could be used as well. A comparison mercial FM gear in amateur operation is with \V\VV at 10 me ensures output on ex­ placing all of the units on exactly the same actly 150,000 kc. frequency. Slightly off frequency operation We have a local BC station on 980 kc. A with this equipment results in a marked falling self excited oscillator is adjusted to 980 kc by off in sensitivity, and in the absence of other reference to the BC station and followed by a symptoms, everything else may be suspected tripler to 2940 kc. Since all BC stations keep but the true cause. within a cycle or two of assigned frequency, In amateur operation being on the exact the 2940 kc can be assumed exact as long as frequency is unimportant as long as all stations zero beat is maintained. are on the same frequency. A convenient way FREQUENCYCOtfTl'IOl of ensuring this is to designate one station, ON TRANS MITTER 980KC 00.000 KC BEING CHECKED ACOJRN:.YCHECKED usually the net control, as a standard and zero .eo::ctIRAcY Q£CI([O VA.'llE:O fOR ZERO BYREFEREMCt TO all other units on that one by means of this WITH WWVATlOIIIC BEAT AT 2940 KC IlAOADCAST STATION modified heterodyne frequency standard. ~~~ When the outputs of two transmitters within 10 kc of each other are combined in an rf IH AL STAfC)ARl) I I Fa. xym I I BC BAH(! QSC I detector the result will be an audible beat­ 2000 KC OR ecce KC 6121.SKC WPaC 980KC llTAl.,.OSC note representing the difference in frequency. 1 \Vhen the frequency of one of the transmitters 1 xa 1 is varied until the beat note becomes as low as Kl.OOOKC xa1 OSC 980KC possible and fin ally disappears, both transmit­ I ,I, 1 ters will be on the same rf frequency. A mobile .so,OOOKC 1 can draw up to the curb at the standard sta­ xa 1 I .1 tion, place this 'difference meter' on the fender I ~ Q OOK C 1410 eoKC 294QKC or trunk floor and with both carriers on, zero his transmitter exactly on frequency in a mat­ ter of seconds. In like manner the mobile can "".",,/ then carry the standard frequency to other 2940KC fix ed or mobile stations. Since sensitivity is no problem, the most rudimentary type of rf detector will do; in fact a portable grid dipper or a fi eld strength meter with phones can be CO/IIlIlllUNlC AroHS RECEIVER AT used. The circuit illustrates a tuned circuit, 2940 KC diode detector and transistor amplifier which, together with two penlight cells, can be built into a very small aluminum box. A piece of 150,000 minus 147,060 ( the frequency wire a foot or two long serving as an antenna being checked) is 2940. A small portion of gives enough pickup for an audible signal in the output of the transmitter and the 150,000 the phones. kc output are placed across a mixer consisting \Vhen it is desired to establish a net on an of a 1N34 diode and a tuned circuit at 2940 exact frequency it does not necessarily de­ kc. The result is compared in the station re­ mand an expensive frequency meter. It can ceiver (tuned to 2940) with the output of the be done with equipment and parts found in 980 kc tripler. Varying the crystal of the VHF any ham shack. The following procedure is transmitter for zero beat at 2940 kc will then used to set one of our nets on 147,060 kc. indicate operation on exactly 147,060 kc. In \ Vith obvious modifications it can be used for making a frequency check the receiver is tuned most 2 or 6 meter channels. quickly first to 980 kc then to 10 me and then A 2 me crystal oscillator is followed by a to 2940 kc for the fin al check. If a suitable BC quintupler to 10 me, another quintuplet to channel is not available the self excited oscil­ 50 me and a tripler to 150 mc. Two dual tri­ lator can be kept on any selected frequency by odes suffice, since little power is needed. A 5 means of an ord inary 100-10 kc standard. 73

54 • 73 MAGAZINE JANUARY 1961 (1296 from page 11 ) You will note no mention has been made of use of modulated oscillators or radar if new!. .. strips to get going on this band. Amateurs proved this type of UHF-VHF equipment CLiMASTER obsolete 20 years ago, so consider such garbage a waste of time. I have e APX-6, much modi­ INTERCEPTOR fi ed, etc., around to work out antenna patterns en entirely new concept with and so will you, but consider the time in VHF receivers- spent trying to talk to someone else with it a The INTE RCEPTO R features all the desl reble waste. If you are going to use " wave tanks q ualities of the best crystal controlled conve rters anywhere in the 1296 me portion of your with all the benefits and performance {actors of Xmtr. don't use 432 me equipment for drive to the best tuneable converters. The combined per­ Ic rmence teeters solv 6 the a ll too num erous a tripler. Triple from 216 me to 648 me and defects of most ellisting VHF receiving syste ms. use a doubler to 1296 meso Note some of the ed venteqes offered : If the above seems like a lot of work and • Complete freedom from cross modulation too much trouble-then stand on a mountain • Superior image rejection and use a flash-light to another such set-up­ • Neqliqible IF leak through • Ex cellent frequency stability you will then have communicated on some • 6 a nd 2 meter operation with a si ngle compact real-high frequency energy, but meanwhile sell-confeined unit W1FZJ, W2CXY, W8LIO, W9QXP, K2GQI, • Costs less than one-half of crvstel controlled W2TT~I , K2HAC, K2TKN are involved in the conve rters end tuneable receiver combi nations • New CliMASTE R styl ing- matc hing the new most interesting phase of amateur radio yet. MER CURY and ZEU S transmitters We have standards-the frequency is 1296 me - exact, and polarization is horizontal when et W,I...., ."0 . h.... on ,hi. unil. pointing at the horizon due south on a polar mount. DI~: ~:~:~~~ ~~C. Most of us have no special test equipment, e99 It. 53, Mt.Ta bor, New Jerse y . OAkw ood 7-6800 none have any money, any of us are more than glad to prove that any available equipment or parts provided by the few interested manufac­ turers will or won't work effi ciently at 1296 me, and we all welcome interest by any other amateurs. Please don't write asking for exact info on this or that, for I have no time to descrihe equipment that is obsolete by the time this gets in print- scream, holler, and insult W2NSD and he will see that articles appear in "73" on anything enough of you have interest in, besides we need the money! Seriously, Grote Reber summed up the whole situation very well when he was the first amateur working on these frequencies Ask for O.E.M. Prices. 0·50 p.A DC. ." .$8.95 some years ago-"There is much to be done!" 0·1 00 p.A DC 7.95 0.200 IJA DC. . 7.75 0·500 IJA DC. . . 6.95 Air Force MARS SO-0-50 IJA DC.. . . 7.95 100-0·100 IJA DC.. . 7.75 Eastern Technical Net 500·0·500 IJA DC... . 6.95 0 -1 Mil. DC.. . .. 5.95 0-5 Mil. DC..... 5.95 Sunda ys, 2-4 pm EST. 3295: 1540, 15,715 kc. 0·10 Mil. DC 5 .95 J an. I-No broadcast. 0·50 Mil. DC 5.95 0·100 MA DC. .... 5.95 Jan. 8-Ellotic Applica tions of Semi-Conduc­ 0·300 MA DC_ 5.95 tors. 0-30 voe 1000 U. 5. 95 0·300 VDC ~r volt. 5.95 Jan. IS-P",ssive Satellite Communications. 0·150 VAC 6.45 • D'Arsonvgl Type Movement ·20 + 3 VU 7.95 • 2.5% ACCURACYI Jan. 22-Some Aspects of Extre-Terrestriel 81atk bakelite t asel Communications. Production Quantities • 90° stale art! Ayailable • f its 2)/. '" Mountin g Hole. Jan. 29-Plasma Physics. • ••••••••••••••• • •••••••••••••••••••• Feb. S-Tih ation with HF Radiation. ~ IL Ii"" inl Electronic Products, Inc. Feb. 12-The Electronic Emission Microscope. t~ ~ ~ 3 Wolcott Ave., Lo .... rente 23. Mon .

JANUARY 1961 73 MAGAZINE • 55 See-Sow Bleeder

P",t Miller KV4CI P. O . Box 701 St. Thoma s, V. I.

OW would you like to save up to ten dollars bleeder clamp t ube. Under "key-up" conditions H a year on your ha m r ig? If you are an the bias cuts off the kever t ube. Under "key­ active CW ham , the following article will give down" conditions bias is shifted from the keyer you some good tip-off's on how to cut the cost tube, allowing it to conduct, a nd is put on t he of running your rig. grid of the bleeder clamp tube cutting off the The term "watts Per Dollar" has been used cu rren t in the bleeder. A small plate relay, frequently in con struction articles but invari­ sing le pole, double throw, is used to do the ably it has been in reference to the inital cost keying and st eals a few mills from the low of the components. Little thought, by radio voltage power sup ply. hams, has been given t o the every day con­ s umpt ion of useless watts by their transmit­ ters. The worst offender is the power sup ply bleeder, frying away and adding useless heat.

Commercial communications companies, with --- 62 their eyes war-ily looking at their electric bills, we --- took up this problem a long time ago and carne ,.. up with what could be called a "See-Saw" 2,K/200. bleeder. The design is a simple one and • .or amounts to nothing more than a clamp tube in series with the bleeder which pulls a lot of current under "key-up" conditions and clamps '~'O'~"~i-f~-~-~-___ 6146/807 off t he bleeder u nder "key-down" conditions. o-.,,::o,,";,;';':W.J We radio hams use this device as a source of ,,,,, 'o0'w screen voltage from the HV su pply b ut then 'W blindly proceed to add another bleeder in par­ allel with the clamp circuit. Such design does - nothing but add heat and st ra in to the power Fi g. 2 su pply. At KV4CI one of several methods of putting For those that use grid block keying a s ug­ a "See-Saw" bleeder to work was put into gested circuit is shown in Fig. 2. Here the action; see Fig. 1. This circuit is a bit fancy normal grid leak is inactive under "key-up" as it uses a keyer tube to key the screen of the conditions, acting only as a grid return for 4-125A final. However, the sa me bias that the bleeder clamp tube. Under "key-down" con­ keys the keyer tube is used to unclamp the ditions the bias source is practically shor t ed Fig. I out leaving only enough protective bias to keep the ampilfier cool if it should accidentally be off-tune. The same left over bias is used to clamp off the bleeder tube. Fig. 3 is another variation wherein the vol­ 20'"0. tage appearing at t he plate of t he clamp tube 6146 "'w" under " key-down" conditions is used to sup­ ~o , 'w 6146 ply the screen voltage to the amplifier. A vo l­ ----- ~~~ '~ A tage regulator t ube cuts off t he screen voltage --- entirely under "key-up" conditions while a --- --1--- small amount of negative bias is imping ed on the screen to assure full cut off. If you p roj ect your imagination on your own you can come up with at least a half dozen variations on "'"".,T....LOftEO... this theme with one of your own possibly more "OR won . tlESllUBI.£ RISt TIM[ suit ed to your circuit design. (Continued on page 59 )

56 • 7J MAGAZINE JANUA RY 1961 Leiters

Dea r Wayne: MOBILE It' s a helo fanote when I ha ve to get. t he in for ma tion on 73 Magazine from E ngland. POWER I had heard a few feeble r u m bles t hat you ha d s ta rt ed ram-roddfnz a new rag. but, t h in k I cou ld find anyone SUPPLY w ho knew t he s lightest thing a bout i t ' H A W! W e ll. I finally s n a g g ed a copy of 73 , t h a n k s to MOD EL W3NNK , who picked it up off a news sta nd back ('8St A12 / 600/200 and brought it with him to Texas. I was rather pleaseol with the fam iliar format and policy ou t li ne. 1 only hope you continue to follow )"our implication that 73 ) IBgazin" NOW will deal mainly with construction-type articles of ad­ vanced t echnica l interest. Some of the other a va ila ble mnll:'n:dnes a re g et t i ng rathe r p ed antic . $59.50 A n u mber o f yenra 8kO, back befo re you were on HTT¥- a nd st ill h ad hair . t here were n couple of in to j-, This 12V input d e to d c transis torized converter is (>B l ing, to m e, colum ns in CQ, One was " Pages F rom an conservotively rated for co'lti nuous output o f 120 Jo; ml"i neer s N otebook,' dealing with old, n ew a nd u nusual circuit applications, a nd m a inly consisted of chatter a nd watts a t 600V or 300V, or a ny combination of 600 scr ibb led sketches, very much li ke coffee-br-eak convet-sa­ a nd 300 volt loa ds totaling 120 watts. tion. The other column." T he Hraaspoursder-," was con­ eerned with our primary mode of transmission, C VW'. High e fficiency, small size, a nd light weight, plus It showered roses or threw brickbats at C W operators, with no holds barred. It was a very frank d iscu ssion freedom from maintenance. conserve your battery of good and bad sig na ls anti/ or oper-atjng tech n iques and increase the enjoyment o f mobile operation. henrd or worked by the writer of t he colu m n. I USE'l l to chat w it h h im every evening on 7020 ko but have n't heard h im (or yea rs. F or t ha t m a tt er , I've been ou t of the States for y oa rs-c-met ynu in Wieslmrlcn , Ge r m a ny ElECTRONICS DIVISION la st year. H ow about consfdertnz somet blnz like t hat for 73 1 GLOBE INDUSTRIES, INC. W a)'ne, YOU can see I'm rather partial to CW, anci it has been a lonR' long time stnee anyone had actively 525 MAIN STREET and frankly discussed t he " a rt" of transmitting GOOD BELLEV ILL E. NEW J ERSEY CW o Believe m e, it was a pleasure the other day to hook up with a n old retired Maste r Sgt. out in A lpine, Texaa'l-.!~~~~~~~~~~~~~~~~~~~~~~~~~~~~ It was the first t ime in years I was able to take t h e weights off t he "bug" and hla st, (l a lao have a COM· PLETE RTTY station- prof_sional g rude.} Wants I have no argu ments a bout A 3, A3a , or A 3b, bu t Ian't Dea r Wnyne, it a fact t hat when t he banda h ave g one dead, a few You r "73" is grf;'ut, I like it. Le-e have some RTTY CW m en a re st ill m anfully chugging a way. r ead ing copy, articles: 144 m e and UP ; informa tion on how to build h a lf ima gina t ion and half noise b reaks ,T hat 20 db wavegu ides and cavity resonator s : m ost com mon troubles advantage over A M is miR' h ty hard to deny. with T T machines. Stan Wilson W9 1FZ O tT t he record, W ay ne, it looked like you shook the SOPII('bodj."serite thou articles f or S tan. ,. "'('au! • .• cd, bucket a bit to come up with that collection of articles in the 2nd Issue of 73, but it was a darn good start Dear w a v ne : in the right direction. Everywhere I go on the air, people are mentioning Dwight B. Olson W 9EAM you r maglldne ! I never- fa il to hear a fellow say 73, Vo n O rmv, Texas r ight before he s ig ns off, AI Brogdon W 4UWA/K3KMO 1.0t$ morc III thc bll('kl't , D w ight , .. fVoYlle, State College, Penn sylva n ia

IN THE _ . , • WEST. It'. V\VIE§~~iE'I~N

~ -'"h,& .•t•• -~ FOR OVER 2S YEARS ONE OF THE WEST'S OLDEST AND LARGEST FIRMS DEVOTED EXCLUS IVElY TO AMATEUR AND ELECTRON IC EQUIPMENT. 1331 India St. San Diego 1, Calif. P. O. Box 1728 BElmont 9-0361

JANUARY 1961 73 MAGAZIN E • 57 •

Subscription Department

Big Brother is watching closely to see if you are really in there subverting other hams with the insidious germ of home-brewitus, Please note the secret invisible ink markings on the subscription blanks so we can tell whether you have been leading to the mental ruin of your friends. We can tell, so you'd better get the old scissors out and get your friends in the same leaky boat with you. ( Huh?).

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58 • 73 MAGAZINE JANUARY 1961 (SEE SAW from page 56) ;-----PLEASE NOTE ---I Not only is t his a money sa ving device, it is also a method which improves the overall vol­ Hams south of Boston, Mass. Bob Graham tage regulation on a C\V rig. For example at WIKTJ now has another exclusive amateur KV4CI the "load-no load" conditions for the store at 1105 North Main Street, Randolph, 4-125A final were 2400 volts loaded to 250 rna On Route 28, one mil e south of Route 128. and 2700 volts no load except for regular Telephone: WO 3-5005. bleeder. T he p icture changed dramatically after installi ng the "See-Saw" bleeder with SURPLUS BUYS 2600 volts at 250 rna and 2750 volts under 90,OOG n . military ObSHTaUOn unit hu a aun anglj 0f:::~ "key-up" conditions. So I enjoy the double Iystem : Contains 16 mm n & H eamera taking ling e _ ntctu ree solenoid driven. 8 day aircraft woe chronometer, ~~~ bonus of money sa ved and a couple hundred cilion lena and mirror I)·a tem. COffi Pan. barom eter , COU ll • OperatH 12 1'. Brand Kew. Perfect for nature lnd!!strl.al, Ct' ~~ more volts on the final to help fight the QRM. tlal photos. Orld nl l g01't. picked. r.o.b. Utica. ~ . Y. or Holb-wood. (Please .pedty.) $35.00- Brand Ne w l 2-meter mobile cOllxlll1 antenna. c}l nlm ll . •••..••••.... $ 5.95 UK/200,*, HO·8/U 50-n. with cormt'c tlil'l • •.. •.. .. ••...... ,...... 2.95 • HUlk ItG·5S/ U new 05/H' 2 ~It.tlOOW H ulk HG -8A/ U new •••••• •• •••••••••••••••••••••• •• _08/ • SLlOEII: T YPE liS -SO beadllhonea 600 ohm, _...... 1.39 HC-603 receiver, as II ....•.. , ...... 9.95 a-meter Oonaet Com municator ...•••••. .•. ...•...••.• 1 4 ~ . OO 2-wl:'t.er Gon.t't Com municator IV ••...••• ..•.•.•..• .• 290.00 4 -125A 6 146/B07r:t-,. 6-meter Gon.et LInear _•.•.• ... .• .•. ••• ..•....•••. _.. 89.00 CITI-FOXE ctnee n'e Bli nd 'rrensceteer with 2 ael, of 9 --- crYl tal, •• ••••.•••••. ••.• . •..•.••. . ...••..•...... 89. 5 N EWEST V AL LEY D ISTRIBU TORS FO R HALLI CRAFfERS AND GO NSET ."" \\'e will take anything in trade. We alao buy used ham aear. ""',. Harry W6ATe WIIlXly K6BXW "2'" . .'M AlyaRadio Diy. Standard Electronics 520S L . n ku~ i m Blvd. Nerth HollYW llOd , Calif. TRian,le 1· 211 3 -1~ O T EI,ETVI'EWIlITEIl EQUII';UENT COLLINS 51J2, 51J3, R-390A/ URR Receivers (.52 -30.5 MC) TElETYPE Printe rs # 14, # 15, # 19, # 20, _ 26, :28. KLEINSCHMIDT Printer, # TT-4 A, TT-76, TT-98, TT-99, TT-100, GGC-3. TElEWRITER frequency Shift Converte r. BIAS OPTIONAL For general information & equipment litt w rite: Tom W 1AFN ALLTRONICS-HOWARD CO. Fig. 3 BOle 19, Botton 1, Mo n . Ri chmond 2-4048 You will note that 6146's are used in my THE MIRACLE IS POSSIBLE • THE IMPOSSIBLE CAN circuits.I happened to have a half dozen used BE DONE ones laying around. 807's, 6L6's, 6Y6's, all of ITS NE W, ITS COMPACT, ITS POWERFUL, them will do the job equally well. 73 ITS LOW IN PRICE PRICE (6 and 2 from page 15) $39.95 The clipping level is then increased with the Net te Ama teurs, clipping control, just above the point where Complete w ith Tube a, See Your Dealet , the two bars meet, but do not overlap. SE ND MONEY Tests were run on both 6 a nd 2 meters a nd ORDER . the stations worked were asked for a report Prices Subject to Change wi thout on sig nal strength, frequency sta bility, modu­ Notice . lation percent and quality. Results were really TUBE COMPLE MEN T great. Stations one hundred miles away a nd on 5163 f inol Amplifiet 6AQ5 Modulator the other side of 2000 foot mountains were 6U8 O, cillotor Multipliet worked with S9 plus signa l reports! Most VHF 12AX7 Speech Amplifiet amateurs agree, as I do, that 100 watts on 6 EXCELLO ELECTRONICS PRESE.HTS . ANe w Low Price V.H. F. Six Meter Tr o n t ml tt ~ r Wired a nd 2 is almost ideal. Increases in power beyond ond teste -d with tubes. The Exce llo Mark II SIX M.eter this point do not result in much improvement, Tro nt miUer it the lowest priced tix me ter trontmltter on the ma rket toda y. This is not 0 kit, but a comp le:e unless the power is increased to 5 or 6 hundr ed un it, reod y to put on the ait with ony power t up p y watts. (Oh the TV! !) supplying 300 v , e t 100 m.c; I can report TVI from the rig is very low. TRANSMITTER FEATURES Meter Indica tot -Provid ing monitoring of Finol Tuning, Trouble was experienced on cha nnel two when Grid Drive Cl nd Modulation, CI t a gl a nce. operating on six meters, but channel two is Tun ing Controlt-Tuning Contra lt a re all on the Front Panel. I • a fringe area sta tion in my area, being 80 Acce n to Components- Removable Enc oture g ives ee- miles a way. This was t he on ly channel ef­ cen ta 0 11 Compone nts . •• . T.V.1. Supp renion-T.V.I, SuppreUlon It a ccompl lt hed fected when t he rig was properly tuned and by 1hielding end detign. ,.. , matched to the antenna. For a r ig which win Compoct Sile-Complete tile of unit it ""x~ ' x6 ma.­ ing it one of the Smollest Six Meter Xmlttera e vetl­ enable serious work on 6 and 2 meters, you ob le. will have to go a long way to beat this com. Low Power Consumption-250-3oo v, a t 7S m.o, 10 bination. 73 Woth on the Ante nn a . Excello Electron ics Co. JANUARY 1961 73 MAGAZINE • 59 196-10 116th AVE" ST. ALBANS 12, L. I., NEW YORK L- LA u,.lton B~3804 --1 ------. ""

75-BUILD.A.WARD QSl ALBUM- Mount your p rize QsL's in this album. Room for 100 cords in ea ch a lbum p lus Radio Bookshop labels for just obout all ponible operating ewerds. A fine woy to show off your cords. $1.95 O n the o fT ch ance that someon e may r ead this BO-sURPLUS RADIO CONVERSION MANUAL VOLUME a d who h a s the b ug to re ad a little on t h e ir favor ite subject, we've laid in a s tock of t he NO . I (second edition). This book g iv es circuit ete­ following books: grams, photos of most equipment, and rather good and complete conversion instruct ions for the following, BC­ I-elECTRONICS & RAD IO ENGINEERING- Terma n. One 221, BC·342, BC-312, BC·348, BC·412, BC ·645. BC-9.46B. ;:,f the mo~ t compl ete text books e .... er printe d. 1078 pages. Theory, b ut easy on the mo th. $15.50 SCR· 274N 453A series reeet...e rs conve rsion to 10 meter re ceivers, SCR· 274N 4!f7 A series transmitters (con....er­ 2-ElECTRICAL ENGINEERING HANDBOOK-Mcilw ain, sian 10 VfOl, SCR·522 (BC·624 and BC·625 conv ersion Formula s, ta bl es, circu its. A real handbook. 1618 pages. 10 2 meters), TBY to 10 and 6 meters. PE·1 03A, BC­ $10.00 1C68A/1l61A reeel....er to 2 me te rs, Surp lus tube index, cross inde x of A/ N tube s 'Is. commercia l types, TV & 5-ANTENNAS- Kr a U5 (W 8JK). The most comp lete book FM channels. $2.50 on anlenna s in pri nt. but largely de ~ i gn and theory, complele with moth . $11.50 81-SURPLUS RADIO CONVERSION MANUAL VOLUME NO. II. Orig:na l and con ....en ion circu it d iagrams. plus 20- RTTY HANDBOOK- Kretz mon (W2JTP). A-Z of hom photos of most equip me nts a nd full convers ion di s· Teletype. Very pop ula r book, low supp ly. $3.00 cun ion of the following : BC-454/ ARC·S reeeiv ers to 10 21 -VHF HANDBOOK- Johnson (W6Q KI). Ty pe ~ of VH F meters, AN/APS·1 3 xmtr/r('lr to 420 me, BC ·457/ ARC -5 propa gation, VHF circuitry, component limitations, a n­ xmtrs to 10 meters, Selenium rect ifier power units, ARC-5 tenna design and con str uction, test equipme nt. Ve ry power ond to include 10 meters. Coil data-simpli fi ed th orough book and one that should be in e ve ry VHf VHF, GO-9/ TBW, BC-357, TA -12B, AN/ART-13 to a c shac k. $2.95 w ind ing charts, AVT·11 2A. AM·26/AIC, LM fr eq uency meter. ro tato rs. power chart, AR B di agram. $2.SO 22-BEAM ANTENNA HANDBOO K- O rr (W6SAI). Ba sin , theory a nd cons truction of beam', transmin ion lines, B2-SURPLU5 RADIO CONVERSION MANUAL VOLUME match ing de.... ices. and test equipment. Almo,t all ham NO . III- O rig ina l C1nd con....ers ion d iagrams. p lus some stations need a beam of some sort . •. here ts the photo of these, 701A. AN/APN-l . AN/CRC·7, AN/URC-4. only source of basic info to he lp yo u decide wh.t beam CBY ·29125• .50083. S0 141. 52208. 52232, 52302-09, rr . to build or buy. how to instoll it. how to tune it. $2.70 ARA, BC·442. 453·455. 456 -459, BC-696, 950, 1066. 1253, 241A for Jetal fil ter. MBF (CO L- 43065). MD·7/ ARC·5. 23 - NOVICE & TECHNICIAN HANDBOOK - Stoner R-9/APN-4, R23·R·28/ARC-5. RAT. RA V, RM -52 (53 ), (W6TNS). Sugor coa te d theory: receivers, tro nsmitters, Rt-19/ARC-4, SCR·274N, 5CR·522. T-15/ARC-5 to T­ powe r supplies. antennas; simple construction of a 23/ARC-5. LM, ART -1 3, BC-312. 342. 34B. 191. 375. complete station. converting surp lu' equipment. How to Schematics of APT-5. ASS·5. BC-659, 1335A, ARR-2, get a hom license, build a station and get on the a ir. APA10. APT·2. 51.SO $2.85 24-BETTER SHORT WAVE RECEPTI ON-Orr (W6SAI). Rl99-GETTING STARTED IN AMATEUR RADIO- Bere ns How to buy a re ceiver. how to tune it, a lign it; build· (W2PIK). Fund a me nta ls for gett ing No.... ice Li ce nse. $2.40 ing aceen ories; better antennas; QSL's, map', aurora R221-BUILDING THE AMATEUR RADIO STATION-Berens zones, CW reception, SSB reception, etc. Handbook for (W2PIK). Sequel to a bov e. Everyt hing you need to know sho rt wav e listeners a nd radio a mate urs. $2 .85 to build yo ur first hem stcttcn. $2.95 28-TELEVISION INTERFERENCE-Ra nd (W1DBM) .This is sNSB-SOUND-N·SIGHT CODE COURSE . Th ree 10" LP the a ut horitati...e book on the subject of getting TVI out records end instructions for No ... ice code, 0-8 wpm. $9.50 of your rigs and the neig hbors sets . $1.75 SN520-S0UND·N·SIGHT CODE COURSE 20 WPM. Ad­ 32-RCA RADIOTR ON DESIGNERS HANDBOOK- l 500 vc nced course fr om 9-20 wpm, three 10" LP 's. $8.95 pages of design notes on e ....ery possible type of circuit. fobulou'. eve ry design e ng ineer needs this one. $7.SO SNS2B-SOUND.N·SIGHT CODE COURSE COMPLETE. All six LP records. 0 -20 wpm and full instructions. $15.95 40-RAD10 HANDBOOK, 15th EDITION- Orr (W6SAI). This is for and away the be st amoteur rodia handbook As inACl tion gets more headway the prices on books eve r p rinted . Over 800 pa ges. $7.50 w ill be rising. On FebruClr y first the price of #40 goe s up to 58.50. This is CI terrifi c book so you'd bette r order 45-CURTA COMPUTER . The world' s smallest computer. it now. #80·81 ·82 a re g oing up to $3 each. Send for deta iled info rma tion. Ma ke s the slide rule look siclt. Like a big Monroe compute r only hond size. $125.00 52-HOW TO READ SCHEMATIC DIAGRAMS- Ma rk,. Order Form Componenh & d iogra ms; ele ctrical, electronic, ce, de, a udio, rf, TV. Starh w ith ind ividual circu its and carries I 2 5 20 21 22 23 24 28 32 40 lhrough comp lele eq uipme nts. $3.50 45 52 53 57 58 69 73 75 80 81 82 53-BASIC ELECTRONIC TEST PROCEDURES-Turner. This book cov ers iust about ev ery possible type of e lectronic RI99 R221 SNS8 SNS20 SNS28 test eq uipment a nd explains in deloil how to use it for ev ery purpose. Testing : a ud io equipment, recei....erl. transmitter,. tron,istors. photocels. d istortion. tu bes. Name ...... Call . power • .. e tc, $B.OO 57-QUAD ANTENNAS- Orr (W6SAI). Theory. design, construc tio n and aperCl tion of cubica l qu ads. Build-it Address ...... yourse lf info. feed ,ystems. tuning. $2 .85 5B-ANTENNAS FOR CITIZENS RADIO- O rr (W6SAI). Generol co.... era ge, mobile and d irectional a ntenna s for City ...... State ...... 27 mc. bond. Build & tune 'em. $1.00 69-5·9 SIGNALS- Orr (W6SAI).A manu a l of pra cticCl l, detailed dato covering de ,ign a nd construction of highly RADIO BOOKSHOP efficient. inexpensi.... a nte nnas for the a mateur bonds that yo u can build yourself. $1.00 1379 East 15th Street, Brooklyn 30, N. Y. so • 73 MAGAZINE JANUARY 19b1 (DRIFT from page 13) tages vary, and this resistor between cathode and circuit swa mps out the interface resistance variations. Naturally, t he added r esistor is NOT bypassed for rI. The closing entry in this list of stabilizing 3 ELEMENT BEAM $13.95 M odel I ASO..3 Boom 6' x 1%" techniques is t he idea most hams t hink of first S ELEMENT BEAM $19.50 - but it comes last for a reason. The reason Model I ASO..SBoom 12' x 1%" is this : If you employ the first six g immicks, 6 ELEMENT BEAM $32.50 you won't need t his one! Model ASO-6 Boom 20' x 1Y.:z" STACKING However, if you don't want to go through 10 ELEMENT BEAM $49.50 KIT the t r ia l a nd er ror technique of Number Five, Model /A50-10 Boom 2,,'x1 Y.:z" AVAILABLE you'll find this one helpful too. SEE YOUR DISTRIBUTOR Simply regulate t he voltage applied W the -or write for Free Cotolog. oscillator a nd to t he mixer screen, if it's not 621 HAYWARD ST. already r egulated. CUSHCRAFT MANCHESTER N. H. For best results, use the VU t ube closest to the designer's voltage rating for t he oscillator. If t his rating doesn't happen to be 65. 75, 90, 105, or 150 volts, though, take the next-lower u. S. #1ELECTRONICS VR tube. a division of AMBER INDUSTRIAL CORP. And if t here's not room on t he chassis for 1'120 E. EDGAR ROAD (Right on Highw a y U.S. 1) another tube, you ca n still r egulate t he vol­ L1NCEN, N. J.- a cra !o s fr om ESSO RE SEARCH LABS tage. Use two small neon t ubes (NE-2 type works fine) in ser ies, a nd place them under PLENTY O F FREE PARKING! m i nuh~s the chassis. Each neon tube wiII regulate a t 30 b y Public Serv ice fr om N. Y. C. about 60 volts, giving you 120 volts for t wo in OPEN FOR RETAIL ser ies. In many ca ses, you'll find, just 60 volts cfter 1S years of wholesale only-now you can buy choice surp lus e lectroniu- from our enormous and on the osc illator gives plenty of out put. If it varied stocks-ma teria l for the whole e leclromognelic does, use it that wa y- you'll cut down the spectrum. heat problem with the lower input. R8/ARN ·8 75 mc RC VR 7 tube s $ 9.95 RT .. 86/ APW .. 1 Ex c.. for conversi on 10 At this point, you ma y be wondering just 2 melers. New . ...• .. .•. 19.95 what to expect in the wa y of r esults from GO-9 Bra nd new ....•••.•••••• 69.50 SCR .. 522 XCVR EXC W , Tubes ..•••.••.•.•.22.50 these tricks. While no promises can be made SCR-522 XC VR L/New.W . Tubes •...... • 17.50 (there's no way of knowing how bad your pres­ BC .. 603 RCVR New . Wilubes ..•...... • .. 15.00 ent r eceiver is !) I CUll show you wha t improve­ BC..604 XMTR Bra nd New.. W/lube s ...... 8. 50 BC-603 AS Is, Le ss lubes ...... 5.00 men ts t hese t ricks made for me. DM..J.<4 RC VR DYN 12 V. Ne w . .. •. •.••. 5.00 8C .. 458 XMlR 5.3- 7mc. New ...... • • • 7.50 Try them-they'll probably do a s well or bet- PE -117, 120 Power Suppl y, Vibrator .• .. 3.45 ter for you! (!J ill Fa mous PE·103 Dyn. New ...... •. .. .• • 14.50 PE 103 Excell. Candn. •. .. • • . .• •• • 12.50 BC.312 Ne w Condn. . .. •.••••• •. • 72.50 T·26 Mobile Chest Mike, New $1.eO ea .....5/ 3.00 Letters 5F or 5G 60 Cycle Synchro $ 15.00 eo. . .• . ••2/ 25.00 10M FD 600v Oil Cond. New. G.E...... 1.00 Dea r- Wa yne, 15MFD 600v O il Condo New. G.E...... 1.50 You r fi rst two Issues of 73 have been j ust dandy, I'm .COC 25 MFD. 8000 vall Peal. $1.00 ea.•••.•.6/ 5.00 glad I subsc r-ibed early. I n t he future I hope you a nd 73 MP.. 22 Mast b ase , e xc. mobile mt. New ...... 1.95 lay off 1111 sponsor in g of contests a nd a w urda for operate TH O USANDS OF ITEMS- THOUSANDS OF BARGAINSI ing . It's so bad n ow that a rllg'chewer ca n ha rdly open Write for free listing-2S% deposit a n C.O.D. orders­ h is station withou t being besiested with contest n u m bers Minimum order $5.00. All prices f.o.b. Linden, N. J. a nd reques ts for numbers. Or "Say, OM, j ust work none m ore o f us Tail-Twist ers lind we' ll send you a tail for you to twist for you rself." I'm not IIgainst good clean fun, and contests can be fun, Ror a m I against a wa r ds ANNOUNCING THE for outstanding achievement, but the p r esent sit ua t ion is a mateur ra diu is s lig h tly r itl iculous.Don ' t m a ke it 2M CONVERTER worse, Wa yn e. H a r vey P ierce WI,/lOPA $borrcrrs't SUPER LOW.NOISE-CUSTOM BU ILT OK [larv, 'UT'U Cllrb :dllJt little ('IIthu.u·aslI1 we m ight USING RCA',N EW NUVISTOR ha-ce had in that direction, I't·(, been propollenli"g slwrur PAUL A. REVEAL W2ADD BOX 575 cO ll f('sts as a means of a/lI't'iati'lg tire conocstion that has Church Street Stotion, New Ya rk 8, N. Y. built III'• •U a Il Y of the cmltest.f that arc 'With ItS today (o n a >-carl>' basis) arc hanflO1'rrs fro", th(' dim dark apes of h~m radio :I'hen it took two 10'19 wrrkcllds to :l'Qrk any ~I quan tity of stations..'io:(oadays a good op ran tl'Qrk more II A -S \V A P• fh.. ,.'ASTF.ST lea,. 10 b .. y, . ell or n eap 110m Cearl stutions ill 0111' /l iuht that till' w illners used to : (~,,"k durill.fI th r t-uo (Oll trst :1·I·rknds. Apparel/tl)' tile f oot prillts i ll t ime 51 a year bring s you 24 issue s of b argains galore­ PLUS Ihe " Fa ste st Wa y in Ihe World " to profitably err: [rosen IHld llll/i'ss a clamor is srt lIP by dist urbed in. dispose of your old or e xcess parts and e quipment. habitants of onr bonds (lik~ j'oursdf) thcse th i" 9S 11.11 go FREE a d certificate and Ioteat e di tion returned imma­ 011 [orcuer, Sotr the SSB aw d V HF COli tests 1(,/li( 1I I diately if you se nd $1 NOW 10: helped set l IP a f ew y ears back, both of w hich are short HAM·SWAP, Inc., 3S.F Eost Wgcker Dr., Chica go t, III. Qn d pop ll/ar. .• . tVa)·ne.

JANUARY 196 1 73 MAGAZINE • 61

• ;---Allenlion RTTY'eI'Si-.., AN/URA-6 Frequency shift converter units, complete with one CM14j UHH and two CV57/ URIC All you need is a receiver and a Tele­ Advertisers Index type printer to copy signals. This is an if type converter. Input 395·470 kc, output is electron tube keyer for keying 60 rn a Tele­ Aleo . 55 type loop. Original cost about $3000. Built into a two foot enclosed rack. Shipping weight Alden . 45 about 200 lbs. Your cost $295. All ied Radio _ . 64 Cr ,.·", tals. tvpe FT.243, 7725. 7900, 8000, 8100, 8025, 8050, 8075, 8150, 8175, Alltronics-Howard . 59 8225, 8275, 8300, 8325, 8350, 8375, Alva Radio . 59 8400, 8600 any frequency SOc Crvstuls type CR27/U. 7675.00, 7725.000, Amber . 6 1 7775.000,7966.667,8175.000,8180.000, 8202.778, 8270.000, 8613.889, 8760.000, Barker & Williamson . 43 8700.000, 8883.333, 9030.556, 9086.111, 91 19..t44, 929·1.444, 9180.000, 9319.444, Candee . 50 93·l7.500, 936.667 •. . any frequency 95c C entral Electronics . . 5 Hot receiver. AN/ARW-2, 30-.40 me FM d ouble con­ version crysta l controlled superhet. Also contains C legg Laboratories . 55 tl!'n ple te reloys, ten o udi o fi lters. Con be used on CB, 10M or 6M. Exce llent for TT or net f requencies. W ith 28 vde dynamotor (eosily converted to 110 ve e}, Columbia . 53 Shipping we ight 6S lbs., brand new $39.95. C ush craft . 61 We ho ve thousands and th ousond s of 1% I,l! w att (U. 5. made p recision resistors. Only $6 per hundred. a Send for my list. D Ie...... 53 If yo u like lists, woit' ll you see some of mine. J ust ...... osk, thot's a ll. Or come in ond soy he llo. Run W2UFU . EICO ...... 2 SPERA ELECTRONIC SUPPLY Evans ...... 49 37·10 33rd ST., LONG ISLAND CITY 1, NEW YOR K Excello _ . 59 STillwell 6.2199 STilwell 6-2190 E-Z Way Towers . 6 Fair Radio . 53 WANTED: Students Globe Elect ronics . 47 ... no experience necessary G lobe Industries . 57 G ~h a m . Lea rn 59 Build these and 13 other - ~- = -. Ham Radio Ham-Swap . 6 1 pieces of equipment which the Ea sy W ay will enable you to learn Inte rn ational Crysta l Cover II , 1 the in's and out 's of Radio const ruction and servicing La fayette Radio . 7 H am gear. L-R Electronics ...... 53 Neil 48 R-f Signol Genera tor AM XM TR Pete rson _ Cover II I All the necessary parts Pierce Schools ...... 62 and simple, easy to un­ derstand instruct ions ac­ Radio Bookshop _...... 60 company each RTT A Kit, which is designed Shorecrest 6 1 and engineered to meet the most r igid require­ Spera ...... 62 ments. Subscription ad ...... 58 Correspondence courses or resident inst ruction are Te lrex 53 available for both the beginner and for the advanced student in all phases of Radio and Electronics. Texas Crystal ...... 5 1 for information write to: Vesta 49 Radio Television Training of America Western Radio ...... 57 52 East 19th Street New York, N. Y. 73 Subscription ...... 58

62 • 73 MAGAZINE JANUARY 1961 /111111111111111111111111111111111111111111111111111111IIIIIIIIII lIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII1111I1111I11111111111111

Other Ham Publications

ATHER t ha n devote half or more of 73 to t he printing of news of R interest to specialized groups we believe that it is our function to do eve ryt hing possible t o encourage t he publi shers of bull etins which cater to t hese in terests. These bu ll etins bring you t he news you want in far g reater detail and in much less t ime t han is possible in a monthly magazine where it usua ll y ta kes two months for news to get in to print.

HAM.SWAP. Published by Ha m-Swa p. Inc., 35 Eest SIDE BANDER. Offlciel organ of the Single Sideband Woder Drive. Chiceqc I. Illinois. Editor is Ed Shuey. Amoteur Redlo Assocletlon. 12 Elm Street. Lynbrook. K9BDK . Subs li fe $1 per yellr by 3rd class meil, $3 for l. I.. N. Y. Subs include membership to SSBARA: $3 1st cless. $5 e lrmeil. li nd $7.20 special delivery. Pub­ per year. Monthly. Primorily opere tinq news end chit­ lished once " month. C ontains clessl f ie d ads entirely. c h <,1t for the ss e ox 9 .:o09. This is your best bet for on ine xpe nsive WlIY to se ll or swep some qee r in II hurry. W ithin two weeks TH E MONITOR. Mor -J~I( Publishers. 507 West Devls people lire e nswerlnq your lid . Street. O~I I~s 8. Texes. $1 e year, 3 veees for $2.50. Monthly. Lerqelv o pe re tinq news. C olumns : YL, Cl ub Mee tings, Ark tlns~ s News, Mississippi News, Flc rld e FLO RIDA RTTY BULLETIN. Fred W .DeMotte News. OX. Missouri News. MARS. Celifomie Ne ws, W4RWM, P.O. Box 6047, Deytone Beach. Florida. $3 Lo ui sie ne News. VHF News. Oklebome News. Rio pe r year including membership in Florida RTTY GrMde V ~lI e y News, Novice News. Society. Mostly operating news with e bit of technical info now and t he n. A ll IT me n should be getting VHF A MATEUR. 67 Russell Avenue, Rtlh wtly, New this. Jersey. $3 year. Monthly. O pereti nq news for VHF me n. Some tec hnlce! info.

SO UTH ERN CALIFORNIA RTT Y BU LLETIN . Me,6 11 OX-QSL News l etter. C lif Evans. K6BX. BOI( 385. l. Swen W bAEE. 372 West Warren W oy, Arcedle. Bcnlte. Celifomle. Published quarterly. 40; eech: An­ Cellicrnle. $2.75 per year, not including members hip in nuel subscription $ 1.25 (four co pies) by fi rst cless Society. Operating news lind some technlcel erticles. rnail ($ 1.50 for OX stetlcns] , lists ~ 11 QSL Bureeus. This is the oldest IT bulletin going. All IT men should rne neqers fo r rM9 OX statio ns. etc. W hy not se nd also get th is one. Monthly. your old C e llbook to <'.I OX hem? Write C lif for the nam e of someone wh o needs it .

73 HAM CLUB BULLETIN. Me"';n Upton VE3DQX. DIRECTORY OF CERTIF ICATES AND AWARDS. Cia 31 1 Rosemary Rood. Toronto 10. O ntario. Cenede. Evens, K6BX. BOI( 385. Bonita, C~I . C omplete Dlrec­ Sent free to all editors of hom club bulletins monthly tory p lus one yetlr of revisi ons (qu~rterlyJ $3.50. Add to keep t he m abreast of whet is going on with all 75¢ for 1st cless moil; $ 1.25 for elrrnai]: OX stat ions the othe r hom dubs. This is tin excellent source of 1st cless meil edd $1.00. Needless to soy. this is the ne ws fo r putting together your dub bulletins. To sub. most complete collection of dete on the hundreds of scribe to this news b ulletin just send e copy of your ce rtificetes end "words eve lleble. own club bulletin to Mervin. MOBILE NEWS. Published monthly by t he Amate ur Redic Mo bile Society. 79 Murchison Rd., l eyton, E. 10. England. J oining fee e nd I ye~r sub. is $2.50. W ESTERN RADIO AMATEUR. Don Willitlmson W6JRE. 105 17 Heverly Street, EI Monte. C ellfcmie. OX BULLETIN . Don Chesser W4KVX, RFD I, Burling­ ye~r, Monthly. Subs tire $2 per $3.50 for two ye e rs, $5 ton. Kentucky. OX news in depth. Published wee kly. for th ree veers. Operefinq news of west coest ectivltv. 3rd C lass mail $5 year; 1st cless $6 : Airmail $7.50. columns on OX. SSB. YL. end some articles. 48 p~ges . DX retes on request.

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JA NUA RY 1961 73 MAGAZINE • 63 • •

o OTHER RECEIVER KIT the ultra-selective "dx-getting" N h features: LIKE IT! check t e 5 micro'lo\t . H-l00 Better than 1. \\ sW trequenCles • • sensitivity on a 30 me in 4 bands j unes 540 kc to . ote se\ecti'liW • s\y 'lana Amateur Communications Receiver Kit • continuoU 5 to 4.5 ke i ro~b~~e~Pe\ectriCa' ~~n::~r~:~dS ONLY This incomparable receiver kit has a ll • Ca ~o through 10 m~ 't bandswitch 95 the features, selectivity a nd sensitivity on . ted Clrcul $99 of high-priced commercial units. H ere \us\l./e pon . E)l. e M \tip\ier $5 down is remarkable Amateur kit superiority • Built-in Q- u.. ction for Sse at tremendous savings.H ere is a marvel of easy Ella\ted BfO In~e Hf osci\lator assembly, made possible by exclusive plug-in • t running . d bandswitch and p rinted circuits. Includ es tubes, • Constan -. . VRB+ apphe a ll pa r ts, handsome metal cab inet. (9%i x 16 Y;; x M' [mum doft. 10 !4.) a nd etep-by-etep instructio n manual. (Less • tol'HF oscillat,o r throoghout phones, speaker a nd S-metcr .) S hpg. wt., 3 1 lbs . •Printed circultrj -;::;;:=J~ 83 YU 726. Amateur R ec eiver Kit _.$99.95 83Y728. Matching 4· Speaker '" 9.75 S 83 Y 727. S-Meter Kit for above 12.95 ONLy 5 DOWN 83 Y 256 . 100 K CC rystal Calibrator K it 10.95 KING-SIZE TR ADES r------ORDER , t96t ALLIED Catalog ALLIED RADIO. Dept. 209·Al TODAY I free 100 N. Western Ave., Chicago 80, III . I For the complete line of I Amateur KNIGHT-KITS, for o 83 YU726 Knighl.Kit R- I 00 Receiver Kit. I everything in E lectronics, Bee o 83 Y728 Speaker. 0 83 Y727 S·Meter. 0 83 Y256 Col. Ki t I your 1961 Allied Catalog. If you $ enclosed (prices nel F.O.B. Chicago) l haven't a copy, send for it now. , 0 Send Free 1961 Alli ed Cololog. I I I I Nome I serving the Amateur for 40 years I ..L OAn ... , ,,, I I Address I I I ALLIED RADIO I I 100 N. Western Ave., Chicago 80, III . L~~ : : ~~~ J

b4 • 13 MAGAZINE JANUARY 196 1 •• It }Jays to insist on

STANDARD OF EXCELLENCE SINCE 1934 AMATEUR TYPES 40 and 80 Meters, PR Type Z-2 Z-2 R ug ged. Lo w dr-ift. fundamental oscil la tor s. High a cttvrtv and po wer o utp ut. Stand s u p unde r maximum crystal currents. Stahle. long-lasting; + .i OO cy cles $2.95 Net Third Overtone, PR Type Z-9A H c rm eticallv sealed; cali b ra ted 2-t ,OS4.95 Net s Meters, PR Type Z-9A F ifth overtone ; for opera t ing d ircctl v in 6-metcT h:UHI: her­ meticallv scaled; calibratcd .sO to S4 ),lc., ± 15 Kc. : .0.lO" pins. 56.95 Net CITIZENS BAND CLASS "0" Type Z-9R, Transmitter FCC assigned frequencies in mega­ COMMERCIAL TYPES cycles: 26.965. 26.9i5. 26.985, 27.005, 27.015, 27.025, 27.035, Comm ercial Crystal s available from 27.055 , 27.065. 27.075. 27.085. 100 Kc. to 70 Me. Pric es on request. 27.105, 27.115, 27.125. 27.1 35. Typ e z.r , MARS and CAP 27.155, 27.165, 27.175. 27.185. Official assigned frcq ucncic-, ill 27.205,27.215, 27.225; ca librated tile range. Calihn u cd to .00.:; % . to .00 5%. (Be sure to specify manu- facturer of equipment) $2.95 Net 1600 to 10000 K e...... S3.45 Net Type Z 1, TV Marker CITIZENS BAND CLASS "0" Cha nnels 2 thru 13....$6.45 Net Type Z-9R, Receiver 4.5 M e. Int ercarrier, Specify I. E freq uency, also whcth­ .01% 52.95 Net er receiver oscillator is above or 5.0 M e. Signal G enera tor, below transm itter frequency. Cali­ .01% 52.95 Net brated to .005%. (Be sure to specify 10.7 Me.F M, I F, manufacturer of equipmcnt.) $2.9S Net .01 % $2.95 Net 2XP Type Z-9R, Radio Control Type Z-6A, FCC assigned frequencies in mega­ Frequency cycle" 26.995, 27.045, 27.09 5, Standard 27.145,27. 195,27.255; calibrated To determine band to .005%. (Be sure to specify ma nu- edge. To keep t he facturer of eq uipmen t) $2.95 Net \ -1"0 and receiver properly ca libra ted. Type 2XP 100 K <. . $6.95 Suitable fo r conver te rs, experimental, etc. Same holder Net dimensi ons a s T ype Z-2. 1600 to 12000 K c., (Fund.) + 5 K e $3.45 Net Z-6A 12001 to 25000 K c. (3rd O vertone) '" 10 K e $4.45 Net ALL PR CR YSTALS ARE UNCONDITIONALLY GUARANTEED. ORDER FROM YOUR JOBBER.

EXPORT SALES : Royal Natio nal C orpo ration . 25 (1 \V. 57th Sn- eer, New York 19. N . Y.. U . S. A.

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