Contents

4 Nawassa W2NSD/1

The intimate inside story of KC4DXJ

16 Slow Scan Television W9MTP

Introduction and general principled

28 Premodulation Speech Processor W6AJZ

Get a 1 10 2S-unit increase in signal

33 Two Buck Signal Generator . , + h WB4MYL

For 2m FM ^tnd stuff like That

35 Transmitters. Then and Now W2FE2

HistOfV-

4 1 Practical Amateur FM Repeaters K9STH

Next month impractical FM repealers maybe?

58 El Cheapo Test Probes WB4MYL

Cheapskate use for old marking pens

SO Prog Line Power Supply - K6VBT

Actually this wi;t power any surplus FM rig. getting you on FM for beans.

62 Random Accass Switching W9SEK

Some push button control circuit ideas

G5 Diode Receiver for 432 MHz K1CLL

Also receives radio signals - like F M.

73 The Taminy of the HHRW K7TCU

Why hjw ihe wife hate amateur radio when shi? can be induced to grudgingly coex isi with it?

75 S5 Preamp Compressor VE3GSP

It realty does make a difference.

77 Push To Talk For The Sixer WB2YWO

Plus other mocMicattons for this jnd the Twoer,

81 Audio Distribution Panel K3PUR

And phone patch, plus other goodies

37 Voltage Multipler Supply for Scopes . .K2BEH

A 300 volt Transformer tan generale T500 volts tfmaway.

89 VFO Operation tor the Twoer WB6FVW

Usmg th^ Heath HG 10, Should work with rhe Sixer too.

91 /MM Maneuvers VK4S5

Wherein our hero fixes a marine riy, answers a QRR and gets into d«p trouble

97 The Sun and Ftadio_____, . <_____P . + _ , W4ZBE

Silence Itraturu

105 Poor Man's Transcanner ; , WB9FOP

Mating a canning receiver to an FM transceiver, the Regency HR2 and TMR 8 in this case Resutt: an inexpensive transcanner

107 SCR Regulator tor KW PowerSuppl.es W3HXO

More flexible than one of those oid great big expensive V arises and voltage regulate^ to boot' Your HV supply will be obsolete without this

115 The Ideal Crystal Oscillator * * . , . , .K1CLL

For that 1 296 MHi rig you are going to build.

117 The HW 16 on Phone? WN2REW

Simpie modification.

119 FM Adapter WILE

FM gadget lor low band receiver so p( will work with those VHF converters and let you listen to all the repeaters,

127 Electric Trmer W6LM

Turns things (like rigs} on, oif, or whatever you want i29 Circuits—Circuits—Circuits WA1KGO

Enough data for experienced butiders to make do and references foi beginners to get more info.

139 GDO Coil Extension . ,WA0ABI

For short GDOY

141 50 MHz OXing WA6CPP

The band is open a lot more than yt>u suspect. Here's how to get more DX out oi *t 158 Home and Auto Burglar AJarms K6ZFV

Are yOu waiting to get rtpped off before you put in an atarm?

73 Magazine is published monthly by 73r Inc., Peterborough New Hampshire Q3-15S. Subscription rates are Sti far one year in Xorth jAmcrrca and t\S /Ap Code areas oversteas. $7 per yetir elsewhere. Two years Si J tn U.S, and $12 overseas. Three years $15, and 916 overseas* Second class postage paid at Peterborough h'fl and at adtiitutnal tnailing offices. Printed at tfenasha, Wisconsin 54952 U S.A. Entire contents copyright 197:! hy 73 inc., Peterborough NH 03458. rhone: 603 92-1 :t8 73. It s too darned late to nign up for the 73 tour in September and include Moscow, what with the incredibly stow system they have go in a, but it in possible tn go along and hit uli other at ops \f you send in y our $200 deposit immediately. Simd for poop sheets on i/>. tour from Lm Greenr 73, Peterborough NH 03 158. Don't miss the trip of v Ufetime White it looks an if the Bajo jVitevtf trip is filled, there moy he rttom for some xtandbvs . . . see page I 12 last month* Positions are open in the advertising and editortat departments for experienced amateurs. O.l/ or YL . . they don't pay a lot but they are fun . . . arid tWiai i* more important* 73 is growing rapidly. Xow stop reading this trivia and net to the articles , r and most important, ¿t nd in that readers service list The agonies of deep persona} torment will plague you if you don't simd it in,

ckW2

EDITORtAL BY WAYNE GREEN

Caveat Emptor

That means buyer beware. Rather than gQ through long lists of problems that fellows have had with various firms, getting inlo a hassle over nits, perhaps a short list of who to contact for details about what firm is in order.

If you would like consumer info re: HT Specialists, also possibly known as Curtis Communications, in Willow-dale, Ontario,, write to Bob Co bum W1JJO, RFD 2 Tinkham Lane, Londonderry, NH 03053.

Consumer info on Herbert Gordon Company, also known as Bolton Labs, and possibly other names, Harvard, Mass,, check with Charles Terry W4FZX 1300 Shady Lane, Orlando FL 32804; James Sandberg K6HE. 1138 E, Rustic Road, Escondido CA 92025; William Watts WApSQL, 1020 Main, Durango CO 81301; Stanley Allan, R1 Box 99, Durango CO 81301; James Thurber W4ICF Box 373, Boynton Beach FL; Thea Vance, 212 Ellendale, Crown Point IN 46307; Max Fraser VE4MF, Binscarth, Manitoba; Carl Pohlner K3PZF, 1780 Joan, Baito MD 21234; Harvey Wills K6KYC, Box 462, Independence CA 93526.

There is quite a bunch of ham gear made up in Japan that is simply awful, This should not be confused with the fine gear that is being imported by reputable companies such as Standard, Drake, etc., which meet all U.S. specifications. Some of the rigs couldn't meet specs wjthoui a major rebuilding job. For instance the Standard 145. available only from Japan, and equal only in looks to the U,S. imported Standard 146, failed miserably in the 73 labs and seems like a real loser. Please watch out for anyone importing or even selling these - and watch out for anything else they are selling for if they will try and foist a 145 on you they may have no scruples about selling other useless gear.

FCC At It Again

Several of the operators using the WA6ZD! repeater in Los Angeles have received citations tor signing their calls as "'mobile" instead of '"mobile six/' Yes, this really happened. It seems so outrageous that it must be a put on, but Fve seen the citations myself and an FCC engineer did really

ckW2

EDITORtAL BY WAYNE GREEN

spend his time and our money enforcing this obscure and insignificant flyspeck in the amateur regulations.

Step two of the citation process has been more jolting to those using the ZDI repeater. This machine has an input of 146,61 (honestly!) and out put on 147,33 (yep!) with the result that the Tech users, though they are personally transmitting within the Tech band, are being repeated out of band. This brought on more citations from our friendly citation center. The Techs involved answered the citation by pointing out that they were at all times keeping their transmissions within the Tech band. Clearly the persons cited were not in violation of 97.7(c) yet they have received no further communications from the FCC. The result of this is that those cited are afraid to transmit on 146.61 unless they hear further. Many of those not yet cited are afraid to transmit on 146.61. It is only fair that these chaps get ati answer.

When you consider how hard the crew in Washington are working to provide leadership and guidance for amateur radio, it is a shame that problems such as this are souring things at the field engineering level.

The Case for 34-94 Repeaters

Probably one of the most hysterically emotional things that I could write about wouJd be a call for more repeaters on 34-94. 1 know of no way to get more FMers up tight and furious. ! shall write about it.

There is no question in my mind that there is probably more unanimity of mind among FMers on the subject of there not being any more 34-94 repeaters than just about any other aspect of the field. Not only do they not want more, they passionately want the repeaters presently on 34 94 to get the hell off - and now! Km for more 34-94 repeaters.

Before you put my swimmir % against the stream down to my wul known perversity, would you be at ail interested in some of the factors which went into my decision? WelL if you don't even want to know what factors are that are involved, then you do indeed have a closcd mind. Okay, now you at least will give an eye to what I have to say, even though your mind may be made up, no matter what it is - right?

Consider, if you will, that there are more 34-94 repeaters around the country than any other pair. Note that [ asked you to consider this, not draw conclusions from it, Consider

"=■■„. ■ ■ - : ■" r'ZF ■ ■ ■ .-„■ . jJ-j-B^-r. ■ ■-".■ " J J.". .

also that virtually every transceiver on the market today comes with a 34 -94 pair of crystals. There is no other channel pair that is generally provided with new transceivers. Does it make sense to have at least one 34 94 repeater in each area of the country?

The fly in the ointment is, of course, the inclusion of a 94 transmit crystal in most of the transceivers, making it so the 94 channel is often used for simplex operation. And, in most cases, where there is a 94 repeater, simplex gets wiped out when the repeater comes on. QRM = anger.

Okay, next step. Obviously both simplex and repeater operation on the same channel are incompatible. Which should give? Should we try to move all of those 34 94 repeaters to other channels, thus giving the buyers of transceivers no repeater to use when they first get their set? It isn't all that difficult for them to get a pair of crystals for the loca! repeater, so perhaps that is not an important factor Hut is it any more difficult for them to get a pair of simplex crystals such as 52?

No other repeater pair comes near being as popular as 34-94. This means that the amateur who travels a bit must have several sets of crystals with him if he is going to use repeaters in the towns he visits. Be honest for a moment please — can you really say that there are any amateurs who do not travel' Just about all of us find ourselves in another area of the country at one time or another - and just about all of us want to be able to use a repeater when we get there.

Let's say you live in New York and you have the 13-73 channel set up for using WA2SUR. You go to Boston and you are out of business. Even if you are set up for the other New York channels such as popular WA2KEC on 40—995, you are still cold in Boston - and in Philly — and in Washington - and Chicago and so forth.

Would it really be all that painful to have a 34 94 repeater set up in each major city so visitors would have one common channel to use to get acquainted? Would it really be a big bad deal if travelling amateurs with a TR-22 and its 34 94 channel could know that they would have a channel to use wherever they were? Would it be that bad if HT-220 owners, most of whom have one and one only receive channel, could work a 34 94 re pea t-

(continued on page 70)

mBÊÈSÊÊSÊM Over-the-shoulder, mobile, or at home

Completely transistorized, compact, portable. H^Sï Capacity for 6 channels. Built-in telescoping ^BÎSIWi antenna, and connector for external antenna. ^pim^Hi Use barefoot or with accessory amplifier. Ex-g^yigog^^ ternal 12 VDC or internai ni-cad batteries, built-ïn 120 VAC battery charger.

GENERAL: • Freq. coverage; 144-148 MHz • 6 channels, 3 supplied • Push-to-talk Xmit • DC Drain: Rev, 45 m A; Xmit, 450 mA • Size: 5-3/8" x 2-5/16" x 7-1/8", 3-3/4 lbs.

RECEIVER: * Transistorized crystal-controlled superhet« 1st IF: 10.7 MHz, 2nd IF: 455 kHz • Ant Input Imped: 50 ohms • Sensitivity: 1 jl/V or less/20 dB S+N/N • Audio Output: 0P7 W • Built-in speaker.

TRANSMITTER • RF Output over 1 W • Freq. Dev. adj. to 15 kHz max., factory set to 5 kH2F

Complete with: Dynamic Mike, 0-T-S Carrying Case, 120 VAC and 12 VDC Cords, Speaker/ Headphone Plug and 10 Ni-Cad Batteries.

^A-22 Amplifier $149.95 /IMK-22 Mobile Mount $9.95 3BLT-144D Hustler Ant. $27.95

mmmmm

BRGENERAL * Freq, coverage:

35Gfel 144-148 MHz • 12 channels, ilOIS^K ' 3 supplied • Push-to-talk Xmit

Supply: AC, 117V 50-60 Hz; DC, 13.5 V±10% • Size: 7-7/8" x 2-3/4"x 10-1/4", 8-1/4 lbs.

TRANSMITTER: • Transistorized with 6360 output tube * RF Output: over 10 W * Freq. Dev: Adj. to 15 kHz max. • Freq- Stability: ±,001% or less • Output Imped: 50 ohms.

RECEIVER: • Completely transistorized, crystal-controlled superhet • Intermed, Freq: 1st 10.7 MHz, 2nd 455 kHz • Input Imped: 50 to 75 ohms • Sensitivity: 0.5juV or less/20 dB quieting; 1/iV or less/30 dB S+N/N at 10 kHz dev., 1 kHz mod. • Audio Output, 0.5 W • Spurious Sens., >-60dBP

Including transceiver, 3 channel supplied, mobile mount, dynamic mike and built-in AC-D C power supply

Kites Sb^ Amateur Net II

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