Archive for the ‘Building projects and kits’ Category:

2018-09-02 Mims Mistakes In Audio Amplifier

From FB group Building Transistor Radios, 2018-09-02 I already see one mistake. On p.27, Audio Mixer. The R6 is only 1k. The voltage divider R5 and R6 will give a voltage less than 0.6 at Q1’s base, which means Q1 will not be forward biased enough and the circuit won’t work or else sound distorted.

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2018-08-29 High Temperature And Nylon Screws

From FB group Hobby Electronics, 2018-09-01 I faced this dilemma before. I’ve repaired power supplies where the transistor failed because it was not held tightly to the heat sink because of a nylon screw that got hot. I used a steel screw and a fiber washer, and heat shrink tubing over the threads to insulate.

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2018-03-02 One Transistor AM Radio

FB group Building Transistor Radios In JF1OZL’s voluminous archive I found his version of a MW receiver.  It is labeled [2] …. MW-RADIO (see link).  He used a long wire antenna, and an IF transformer with the ceramic capacitor removed for the tuning coil.  He also said to use a ferrite loopstick, which is what

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2018-01-09 Regenerative Radios Are Too Difficult

For FB group Building Transistor Radios Bob Johansen After building several of the regenerative receivers, I think I figured out the reason why regens are so difficult.  The circuit has to do so much with very few parts.  If one part value is changed to improve one thing, it adversely affects something else.  The tickler

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2018-01-08 RF Oscillator For AM Band

For FB group Building Transistor Radios When I started building regen receivers, the first thing I found I needed was a simple  signal generator.  I have a function generator, but every time I want a different frequency, I had to readjust the controls.  So I built a few RF oscillators to put close to the

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