Fair Radio Sales

HEATHKIT HR-20 REC., HX-20 XMTR (SSB. VOX, VFO). HP-20 AC power supply. All operating. 200. M- Kaplan, 2303S Lanark St t Canoga Park. Calif. 91304. HI POWER PP4E27 linear amplifier, Surplus item suitable foundation unit for grounded grid per August 73 article. Equipped, variable tank inductor, no junk. 15.00. MegeiT W2DXK, 5015 Weeks Lane, Flushing, New York 11365. SIDEBAND PACKAGE. Swan 240, Heath HP 10 AC supply, HalHcra iters PS150-12 DC supply. 200. Bruce Tepper K6HET, 12402 Killlon Street,...

Baseoiawm

Schematic diagram oj the converter. All resistors are hU+watt carbon. All bypass capacitors arc disk ceramic, Dipped silver mica capacitors arc preferred for capacitance values below 100 but disk ceramics arc acceptable unless otherwise specified. The 1 pL dipped silver mica capacitors are made by Cornell Dubilier. For best sensitivity* connect the 77588 source directly to a ground lug as at A. For better overload control, connect the 1 V191 (or IA'192) diodes across 1 as at CX, and...

Staff

Cover Photo A collection of current receivers available, Top to Bottom and Left to Right Radio Shack Realistic DX-150, Hallicrafters SX-130, Davco DR-50 Hammarlund HQ-215, Galaxy R-530, Heath SB-30J, R-L Drake R-4B, with the Amphenol 830 Transistor Analyzer, McCoy Silver Sentinel Crystal FiJter and associated oscillator crystals Photo by Fred Meyer Studio, Ne*t Month Look for article by Fred Clepper, W3RET on the application and selection of crystal filters*

Controlled Regeneration Just Short Of Oscillation

RF feedback increases the RF voltage suing in the detector input circuit. Suppose ue have a constant, very small RF input. As we increase feedback the voltage siting increases, even though the input voltage has not been changed. Too much feedback results in the uncontrolled-amplitude suings of oscillation and detector sensitivity is reduced. hinking about the sensitivity controls sensitivity, I soon came to some conclusions. It appeared the control itself was in good shape, and the...

Save That Cordless

he age ol the cordless electric appliance is upon us. Anything from a So.00 flashlight to a 60,00 drill can be obtained with a built-in battery and charger, and the list includes such essentials of modern life as electric slicing knives and electric toothbrushes, Sooner or later some of these gadgets quit working and wind up in the trash can. The purpose of this article is to point out to hams that they can be a source o( useful and unusual parts. I he diagram of a typical cordless appliance...

Oscillator Transistor Tone

Do not confuse this wellmade military unit with low price commercial 'ice cube packs, his unit operates from t.5 to 6.0 volts, and has transformer isolated output. Frequency is 1000 Hi, may be varied with external pot. New package, ar d complete with spare set of transistors. Applications Continuity, component, and semiconductor tester, code practice oscillator, keying monitor, alarms, RTTY SHIFT Oscillators, etc. Price 52,00 Postage Paid, TTC 2.00 P.P. 101 New packaged spare parts for models...

Info

And only Radio Shack has this 119.95 receiver Thousands of hams and swl's have discovered that Radio Shack's Realistic DX-150 is truly the breakthrough1' full coverage receiver of 1968. It's the 100 solid State receiver that banishes forever tube failure, tube heat, tube drift, and thanks to its built-in 117V 12V supply your dependence upon AC current when power fails or on field day. The brilliant DX-150 is NOW IN STOCK in every one of Radio Shack's over 200 stores .

Regenerative Detector

Ive thought many times about some of the odd transistor regenerative detector circuits I see in the magazines. Very often they seem to have a certain unreal quality, and I've wondered if they really worked. Don't transistors make good regenerative dctec-tors They ought to, because their characteristics are far sharper than those of vacuum tubes- Yet the 1968 Radio Amateur's Handbook has no transistor regenerative detector circuits, and only one project And that circuit, too, looks weird to me....

Resistons Are

Optional 455 kHz If Strip to replace module. the mixer gets a pretty good shot of rf when a transmitter is operating, if the rf amplifier is left running. Since breaking both the rf circuits and the oscillator would require two contacts on the mute switch, it was decided to let the oscillator run. The power transformer and choke used were surplus items picked up at a local junk store,' and somewhat smaller than those specified in the parts list. If the specified ones are used, the next...

Mhz

Schematic diagram of the battery powered Q Q Meter a Pi network where the in circuit Q is around 10-20 , definitely has too much loss for this application. Many surplus capacitors with low loss ceramic insulators are available and one with a vernier drive is to be preferred. The one used here is a J. W Miller 2111 with the fiber insulators removed and 4 small ceramic standoffs similar to cam hi on 3848-2 added to support the stator, Capacitor is a surplus type OT15 modified to two...

Transistor Type

In my VFO, CI goes directly to the collector of Ql, the oscillator. In the other VFO, the circuit should go in parallel, that is, across, the frequency determining circuit. In a tube type VFO, usually the grid of the tube will be in place. See Fig, 2, If your VFO quits with the addition of this circuit, try a smaller capacitor at Cl. Make CI as big as you need to get the deviation you want and if the VFO oscillator quits before you get CI large enough, use more diodes to make CI just small...

Tfo

The rf stage is a typical cascode circuit using a TIS 88 input and a TIS 34 output. by Robert Z , Morrison WB6YVT 623 Sonoma Ave. Livermore, Calif, 94550 The TIS 88 is a plastic version of the remarkable 2N4416, while the TIS 34 is a plastic version of the popular 2X3823. i le cascode does not have a better noise figure than a single neutralized stage but was selected primarily or its better inherent stability. The TIS 34 mixer stage is biased near cutoff for high local oscillator injection and...

Parts List

CIA, ClB 365 pF, dual variable capacitor C2t C5t C7 0.001 aF, 600-volt ceramic disc capacitor C4--5-20 pF variable capacitor Hammarlund MC-20-S or equivalent C3 Midget A PC variable capacitor See Fig, 4 C6r CH 270 pF, 400-volt mica capacitor C8, C9t C12 - -0,05 600-volt ceramic capacitor C10, 0J, 200-voIt ceramic disc capacitor CUf C23 0,02 F, 400-volt ceramic disc capacitor CI3 35 pF midfeet APC variable capacitor CIS 30 pF, 400-volt mica capacitor Cl6f CI7 500 pF ISC-volt ceramic disc...

Audio

The purpose of this article is to outline some of the difficulties which can be encountered in home construction of amateur band receivers. This is not intended to be a construction project and no parts values will be given, but will deal with the general problems encountered in a year long receiver design and construction project. Although the field of receiver design and homebrew-ing may seem beyond the grasp of most of the casual weekend builders, if a real desire or need exists for an...

Vanguard Labs

Olden Days Measuring Instruments

196-23 Jamaica Ave., Hollis, NY 11423 in the preceding six installments of this study course for the Advanced Class license exams, we've leaned heavily on theory because the point of the whole series is to provide the additional theory you'll need to pass the exam But all this theory must be tempered somewhat with its practical applications. Any practical application of any part of the theory is going to involve some type of measurement even though we may not realize that we're making it. For...

Crl Gn

Values determined from this equation will provide optimum stability and still remain consistent with other oscillator requirements C5 should be small enough to prevent the transistor from being driven into saturation or into cutoff, So, to get to another frequency, calculate CI and C2 select suitable values for CV and C3 and padder C4 at lower frequencies, and then determine the inductance needed for LI to resonate with this amount of capacitance from charts in the radio handbooks. One other...

Cl Cl

YOUR TAPE RECORDER IS READY TO TEACH CODE That's right Your tape recorder is ready to hefp your code study. The CODEMASTER tapes give you professional instruction via your own tape machine. Now generated by digital computer, the CODEMASTER tapes are unsurpassed for timing accuracy. Whether you're just starting, going for your Amateur Extra, or somewhere in between, the CODEMASTER tapes are your best code-learning buy Find your CODEMASTER tape below CM-l For the beginner. A complete course cf...