Old Gernanium Transistor Repair

Nov 13, 2006 62 Replies

Yes, did that and the oscillator definetly stops at low temperature. Measured HFE was 75 so I switched the oscillator transistor with another germanium with HFE of 220. Performance improved, but oscillator still stops at 40 degrees F or lower. I also switched the last IF with a high gain silicon and adjusted the bias and retuned the coils. Performance again improved, but radio still has noise problems on weak stations. The signal trimmer capacitor peaks near the center of the range, so I'm pretty sure the front end is aligned correctly. The noise must be coming from one of the IF stages.

If I can fix the noise problem, the thing should work as good as new at moderate temperatures.

-Bill

Check the voltages on the bases of the first one or two transistors at different temperatures. Check all of the resistors - if you have a low voltage meter that can test without turning the junctions on use it.

then your problem certainly isnt the transistor.

NT

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