Af

This will be real short. Lafayette has a selection of transistor af amplifiers which work fine. You can get up to three watts, which is better for mobile work if you have that in mind. Get several because you'll need another one for the modulator, unless you

500-Watt 5-Bander

You can't buy a more potent package than the new NRCl NCX-500 transceiver. This versatile 5-bander is packed with the performance extras that give you the sharpest signal on the band, plus an enviable collection of QSL's. Check it out!

• 500-Watt PEP input on SSBr grid-block keying on CW and compatible AM operation,

• Receive vernier, with tuning range greater than ±r 3kHz.

• Crystal-controlled pre-mixing with single VFO for effective frequency stability, plus identical calibration rate on ail bands.

• Crystal lattice filter for high sideband suppression on transmit, and rejection of adjacent-channel QRM on receive . . . plus solid-state balanced modulator for ^set-and-forget" carrier suppression.

• Universal mobile mount included.

AC-500 power supply available. Great things are happening at NRCI.

AMATEUR NET PRICE: $425,00

mi inhii

For complete dettf'l* and specification^ write:

NATIONAL RADIO COMPANY, INC.

I 37 Washington St., Melrose Mass, 02176

Telephone: (617) 662 7700 TWX: 617 665-5032

International Marketmr through:

Ad. Auriema, Inc. 85 Broacf Street, New York, New Yofb

© 1969, National Radio Company, Inc,

fO TUft N 5

AVC LINE Ttt 2^0 STAGE 3A5E RETURN

Fig- 14. Third stage, if, 6 m.c want to do a lot of switching between microphone and speaker, etc. You can even get three, one for the modulation checker when tuning up the transmitter. Once you use this trick, with a diode and padded earphones, plenty ofaf gain to keep your voice from getting to your ears through the air you'll never be without it. You can hear every bit of hum, distortion, etc. that can creep in, and, if everything is correct, your own voice coming to you through the mic, transmitter, and antenna just as it sounds to the lad on the other end of the QSO, With the exception of unwanted FM, if any. That is another story.

Assembly

When you finish these receiver units you will have the receiver half of a nice portable rig. I have found a simple carrying rack of plywood, with as many shelves as you need, and a dowel handle on top, sprayed with aluminum paint, to be very useful. The receiver is really very simple, just a standard super-het. It helps though to know you can plug in a crystal controlled oscillator chain and narrow band if check the mixer without the rf stage, build more rf stages and add or substitute them as desired.

Leave shelf room for a modulator, transmitter, and possibly "high power" addition. Two watts? Five watts? Who knows what the future, along with a little more hard work (and S) on your part, will bring you? Mount the speaker in a little box., removable, so you can place it off the rack. Audio feedback gets to the tuner through the rack itself. Or you could use foam rubber mounting to handle that matter.

Final tune up

This can be troublesome. It was here. Quite a few cables to make up, but worth it in flexibility, 1) Antenna to rf 2) rf to mixer 3) Oscillator to mixer. 4) Mixer to if 5) Mixer to af I put two lantern batteries on the bottom shelf for a total of twelve volts, with the af amplifier in front; the if on the next shelf, and the rf head on the top shelf. A new and taller rack will be made up for the transmitter units later.

Checking back through the circuits you wili notice cable matching input capacitors going to almost every base. Some judicious testing of cable lengths can help, because, unless you have a slotted line and do a real professional job on the SWR like when someone else is paying you for those extra days, be happy with a few standing waves.

A simple test signal unit with two tripler stages from a 48 mhz crystal, to 144 and then to 432, was used as a test oscillator with a nine volt transistor battery, a dipole, and a modulator, and >laced about 100 feet away. Works fine but sure swamps the S meter. Then came a little glop of trouble. After all my warnings about frequency checking on multiplier frequencies, it happened to me right on my own bench. I tuned up the complete receiver, ound the test signal generator on the dial, and proceeded to test the rf mixer, and oscillator stages, using the full gain of the if Nothing worked right, and no wonder, I had inadvertently tuned in one of the higher harmonics of the test oscillator over 500 mhz, right alongside of one of the Massachusetts UHF TV stations, and then, to make matters really sticky f had, also by mistake, peaked up the test oscillator near 525 mhz too!

On checking with an old but calibrated coax mixer, everything seemed to be over 500 megs. Which it was! Just part of the game of course, so, as I keep saying, check that frequency.

As soon as everything was put back near 432 the new job showed up as having real pulling in power. The rf and mixer peak up nicely, and the oscillator is quite stable.

With the front end as described in the text and figures, it is quite easy to get too much oscillator voltage into the mixer, Oscillator harmonics will then show up as CW signals, but tuning much faster on the dial, because when you move a megacycle at 432 the harmonic may move two or three. Reducing coupling into the mixer by either the capacitor or the oscillator link, or both, cures this. You don't need that much signa; for a local oscillator.

Listening in a little

If you hear a strange humming noise, going up and down in volume, tuning very broadly, near 420, and again maybe near 500 mhz, shut off the rig, go outside the house, and listen for a big plane- It's one of those altimeters!

This was just an indoor antenna test before putting up the big beam outside. Also heard were the Mass. TV station on 425 mhz and a very loud pulse signal on about 430. It will be very interesting to see just how far two rigs like this will be able to maintain QSOs,

All I need now is that matching transmitter.

NEW Heathkit SB-500

2-Meter Trans verter

Heathkit 104 Manual

• Provides complete 2-meter capabifity for SB-101, SB-110A, HW-100 and The SB-301 /401 combination

• USB, LSB & CW operation • 144 to 148 MHz coverage • 130 watts PEP input 50 watts PEP output • Highly sensitive receiver • Fast, easy tuning ■ No cable switching * Handsome SB-Series styling

• Provides complete 2-meter capabifity for SB-101, SB-110A, HW-100 and The SB-301 /401 combination

• USB, LSB & CW operation • 144 to 148 MHz coverage • 130 watts PEP input 50 watts PEP output • Highly sensitive receiver • Fast, easy tuning ■ No cable switching * Handsome SB-Series styling

Now, in answer to many requests, Heath has a fast, low cost way to put you on two meters * . . without having to buv a whole new rig. If vou own an SJMOJ, SB-110A, HW-lOOor the SB-301/401 combo, youVe almost there. Here are the details on how to get on "2" — the SB-500 way.

Here's How It Works, I n lhe receive mode, the SB-500 taktis Lin incoming 2-meter signal and heterodynes it to either 6 or 10 meters, where the low band gear handles it in the usual way. On transmit, a 28 or 50 MHz driver output is heterodyned to 2-meters, amplified and coupled to the output.

Here's What It Delivers* When used with any of the gear above, the SB-500 2-Meter Trans verier gives you complete 2-meter SSB or CW transceive operation from 144 to 148 MHz. A pair of inexpensive 614G*s in a push-pull ABi circuit deliver a husky 50 watts output into a 50 ohm nonreactive load. Final plate voltages are derived from the driving unit, but all other operating voltages come from a built-in power supply - - no extra supply to bu\, Receiver sensitivity is 0,2 uV for a 10 dB S-j-N. N ratio... that means solid copy QSO's. A front panel oil-oflF switch places the SB-500 into operation or allows the low band gear to operate straight through to an antenna or drive a linear , . , n combination of complete rear apron jacks and internal relay switching eliminates troublesome cable changing. Reliable relay-controlled I R switching too. Tuning is fast and easy, and a built-in meter monitors either final plate current or relative power. ALC voltage is supplied to the driver to aid in preventing over-driving and distorted signals. A built-in I MHz crystal calibrator is also included.

Solid, Stable Construction. The sensitive receiver and oscillator yo together on well planned circuit boards. To insure stability and make adjustment more exact, the transmitter and power supply components are ruggedly chassis mounted. The SBoOO comes com-pleie with all interconnecting cables too, Start enjoying the QRM-free world of 2-meters today ... with the new Heathkit SB-500 . another hot one from the hams at Heath»

SB-500 SPECIFICATIONS — RECEIVER: Sensitivity: 0.2 fniero-

volt fof 10 dtí sígnal-plus-ncise to noise rofio for SS0 operalion. Spurious Response: All ore below 0.1 iricrovoJf equivalen? signal input, except ci 1^5.310 MHz (50 MHi IF only). Antenna Input Impedance: 50 ohm unbalanced. TRANSMITTER: DC Power Input:

130 watts PEP. Power Output: 50 watts (50% duly cycle). Output impedance- 50 ohm wilh less than 2:1 SWR, GENERAL: Frequency Range: Any 2 MHz segmenf between 144 & 148 MH* into 50 MHz or 28 MHz funed IF, Mode of Operation: SSB or CW only. Power Requirements; (1) 120/240 VAC, 50/60 Hi at 82 watts (internal). [2} 700 to 800 VDC of 200 mA (from driving umi). Fuse: % ampere slow blow for 120 VAC (formerly 3AG); l¿ ampere slow-blow for 2-íO VAC. Front PaneJ Controls: /'.eter-coJibrafe switch, final luning, off-on (function) switch, preselector, f nal loading, driver tuning. Chassis Controls: Relative power adjust & bios adjust. Rear Apron Connectors; Rr output, ALCr linear relay, reloy, drive, power píug, low f receiver, low f antenna, fusehaider* Tube Complement: 6CB6 Iransmítter mi*er, 6CEÓ crystal calibrator, 6DSJ receiver RF amplifier, 60SA receiver mixer, 12GN7 transmitter RF amplifier, (2) Ó14Ó final amplifiers, (types 6I46A or 614ÓB may be direct!/ substituted], 705? heterodyne oscillotor-amptifier, el 50 Rp driver, 0A2 voltage regulator. Diode Complement: 5 silicon diodes, 750 mA, 500 PIV; 3 in power suppEy, 2 in ALC. 1 Germanium diode, IN191: ftEL PWR. Cabinet Dimensions: V/ * ó* S H x " D. Overall Dimen sions: 1214' W x 7-15/16' H x W D including knobs and feet. Net Weight: 14? ! fbs.

FREE '69

i HEATH COMPANY, Dept. 11-B

1 Benton Harbor, Michigan 49022

plus shipping.

plus shipping.

Please send modef (s).

Describes Ihese and [ n Please send FREE Heath kit Catalog, over 300 other kits. Save up to 50% Name by building them your self. Use coupon and send1 for your FREE I Clty copy

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