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Weird Symptom 42-355
#1

A few years ago I recapped a 42-355, and it worked perfectly for a long time.  In the last few months it's developed a strange problem.

Every now and then, when listening to one of the push-button preset stations, suddenly the sound will drop out.  Sometimes I can hear faint signals from other stations if I turn the volume up, but they are definitely the not station I was listening to when it dropped out.  Other push buttons work fine, just not the one I was listening to when the signal dropped out.  So I think the LO is temporarily retuning itself from the preset frequency, not just losing contact with the band switch / push button block.

The only thing that will reliably bring back the signal from the push-button preset station is to push the AM band dial tuning button, then tune it manually to the station I was listening to, and then push the preset button for that station again.  Works every time.

After that, all the push buttons and the dial tuning work as designed until the next time.  If I push the AM band selector button but don't tune it to the frequency of the push button that dropped out, it still doesn't work.  Somehow the dial tuning has to be set to the same frequency as the button preset.  But once the preset station comes back, it doesn't matter what I do with the dial tuning, until the next time it drops out.

I'm sure this symptom has affected buttons 2 and 5, and probably 3 at one time or another.  I rarely listen to the other presets.

Any ideas?   Why the dial tuning has to be tuned to the preset frequency to restore the button preset is beyond me.

John Honeycutt
#2

Deoxit.




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