International Crystal Bax-1 Schematic Or Circuit


Wayne Green, W2NSD/1 Ralph [race, Jr., WA1GEK Kayla Blook, W1EMV

Advertising Bill Beatty

Production Roger Block Phil Price Nellie Sildar Jeff Barsanti JaneTracey Carol Ring

Bill Kellogg Bill Morello


Mary Andreae Dorothy Gibson


Joe LaVigne


John Nelson

WTW Editor

Dave Mann K2AGZ


Walter Manek Dudley Orr

73 Magazine- is published by 73. inc., Peterborough, N.H. 03458 Subscription rate $12 00 for Three years, S6 00 for one sear Second Class Postage paid at Peter borough. New Hampshire. afliJ al addmoiui nailing offices Printed al Puntuc. Illinois. t -v Entire contents copyright 1969 by 7?. Irw PoitiTiiUcr p1e«< tend form to 73 mifi/iw. Peierborotish. Nc" Hampshire 03-158 Add ten label cypher youc call letters, <houl.1 folio» your name If we've luJ to nuke up a ndl just drop u1- a nole and well change it to your real call 1 lie number under the call is our code for The lust issue on your subscription The first number is the month, the sccond. the year of the last issue. 50 would indicate expiration with May 1970. Renews! notices are prepared ahead >»f lime a-id you may receive one or two after sour «-ubwriptkm hj- been renewed- View this -aniatiun unh humor and toleraikv Tell your friends jboui it. if you mast. but Jon": feel it necevsaiy to lell us. we already know «11 too well about it


4 A DX Curtain for 15 Meten: VE1TG

An easy 3-4 db gain for you, 8 Tunnel Diodes—Theory and Practical Application . . . K8TSQ Including a one transistor solar powered transmitter,

14 The Magic T Thorpe

Method for running rf transistors in paraUel-

19 Unete WÍU and News from «he Poudre Valley K0DVI

In dialect yet.

20 Basic Soldering Outfit W1EZT

Good Lord! Another article or solderingl 24 Light Naturally Runs Down K1CLL

A special Scientific American type feature.

36 Cable Pickup and Shielding W2EEY/1

Keeping interference to an absolute minimum.

39 WWV-Pioneer in Standards Broadcasting WA1AAU

Perhaps you've heard the catchy tune they play

42 Basic Theory and Application of Transistors WA1FHJ

Something you have always wanted to know.

50 Series Gate, Solid State K6ZFV


52 Improving NC-300 SSB Reception WIOOP

53 AFSK Generator W1ESH

Crystal controlled, using digital IC'sno less.

64 Transistor Transmitter Aspirin K0VQY

How to keep from westernizing your transistors. 68 Improvement of Phone Intelligibility by Base Clipping. .. Ives Discussion of base dlpping.

72 Measurement of Meter Resistance WA6NIL

Making it possible to uersatilize your meters.

74 Diode-Stack Power Supplies-The Easy Way K6KA

Instant operation of the Henry 2K and other rigs.

76 Transistor Testing Techniques W9KXJ

Testing with a vom without destruction.

78 2V4W Transmitter KftVQY

Work the world with this three transistor rig.

80 Neutralizing the H X-l 0 W2PQG

Simple way to stabilize this rig.

84 More Taylor Modulation DL5KS

Remember that AM is still going strong on VHP,

88 An Audio Sinusoid Generator W6FOO

90 Capacitor Usage and Electron Flow W0HMK

Where to use what capacitor and why.

96 What About FM? W9VZR

We'll have you on FM within the year.

98 A Primer on Radio Propagation WA1GEK

If signals really do bounce, this is how it works.

106 Measurement of Percentage of Modulation Granger

Of AM Transmitters.

108 Extra Glass License Course, Part VIII Staff

124 Big Signal-Good Looks WA7AIA

3-40QZ kilowatt linear.

129 A New Vidicon Camera for ATV W8VCO

Isn't it time you tried your hand at ham TV?

133 Two More Transistor Testers W9DJZ

Handy if you by your transistors by the bag full.

139 The FET Compressor WA0IOC

Audio compressor using two FET's.

140 The Mike Mixmaster WA2YRF

Just like a broadcast station.

142 The T-60 Works Just Fine WA1GEK

Part XVII of our Novice Instruction Manual.

144 • Leaky Lines K2AGZ

Not to be confused with columns In other magazines.

147 A Unique RF Plate Choke W6RET

Actually it isn't really all that unique

148 Modification of the ac Input on the SB 200 K3KMO

Published by popular demand.

ll'aync Green

Our New Magazine

Last month I mentioned briefly that we are planning to start a new magazine for debut this fall. Since we are depending very heavily on you, the readers of 73, for articles for the new publication, perhaps I should tell you a little more about it.

The idea is to put out a magazine which can be read by the general public and which will carry them on up through the Novice License. 73 is far too technical for the beginner and we are hoping that a magazine can be put out which will fill in this gap.

Remember back to when you got started in radio as a hobby. The chances are pretty good that you started out either in CB or as an SWL, depending mostly on when you got into the game. I went the SWL route myself, but I am quite sure that if I had come along during the CB era that I would have entered through that door. Both CB and SWL can be fun ... a lot of fun. Both could, I believe, use an adult magazine to help people get more fun and education out of these aspects of radio.

For instance, have you seen any articles about listening on much more than the broadcast band or the short wave broadcast stations? What about VLF? I'd like to have readers send in articles on listening to some of the more offbeat bands .. . ship-to-shore, police, fire, CAP, doctor calling, telephone, aircraft, etc. And how about some articles on using RTTY gear for tuning in the ham bands, news broadcasts, stock market, weather, foreign languages, and other interesting services. Used FAX machines are available inexpensively now and can be used for copying Tiros directly ... or FAX broadcasts of weather maps and other items. I think there is enough going on to provide interesting articles for a long time to come.

The beginner won't be able to build very much, so I think we should try and concentrate on telling him how to buy commer cially available equipment and accessories... how to use it . . . what you can do with it . . . how to hook it up . . . and anything else they should know about it. This goes for ail of the CB transceivers, antennas, test accessories, tuners, and gadgets, as well as converters, tuners, receivers, etc., for SWL. CB'ers want to know how to install equipment in their car and how to make it work the best possible way. They want to get every milliwatt out of their system at home or mobile. They want to know all the things they can do with their CB gear that are legal and how to avoid being illegal with it. They should be encouraged to work their way up to amateur radio if they find the need to get on the radio and talk for the fun of talking. That's what ham radio is for and CB isn't for.

Since we will be covering radio up through amateur Novice, we will be looking for articles on Novice gear and on Novice operating. I'd like to see a lot more straight from the shoulder articles which will help Novices enter our hobby with a better understanding of amateur radio. Too many of them get hung up with poor equipment which spoils their fun, just because they don't know any better than to scrimp on the receiver.

The time is already growing short and we are getting the first few issues of the new magazine ready for publication, so get busy writing and let's see if we can turn the tide and not only provide a lot more fun for those coming into radio as a hobby, but encourage them to go on to amateur radio.

If you don't feel that you have an article to write, perhaps you would like to volunteer yourself to answer questions from readers? Send me your name and address and let me know what particular type of questions you can handle in particular, and I'll list you as one of the Technical Advisory Group. Readers will be requested to send their questions to (continued on page 66)

International BAX-1 Broadband Amplifier is a general purpose unit which may be used as a tuned or untuned amplifier in RF and audio application. For example: when used as untuned RF pre-amplifier connect between antenna and receiver antenna posts. Ideal for SWL. Experimenter or Amateur applications. Easy So build. Complete Kit S3.75


2. Frequency Range 20 Hz to 150 MHz

-3 db 100 hz to 10 mhz down 15 db at 100 mhz down 24 db at 150 mhz

5. Operational Impedance 50 to 500 ohms

6. Noise less than 10 microvolts rf across 50 ohms: audio less than .0005 volts

7. Minimum Input Level 01 volts ac

Mounting d holes with spacers

Write for complete catatog.


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