Quote:
Originally Posted by miniman82
Not always. Some of the circuits have the crystal tied in to the plate circuit of the oscilator, and I remember Phil saying the new crystals did not like having that much voltage across them. Best to find one of the old large can style ones that can take the voltage, trick is finding one that's still good.
The CTC-9 I recently sold had a good crystal in it, the CTC-7 had to be replaced before it did anything, and the one in the CTC-4 still seems to be good. So it's hit and miss, I guess.
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This may have been me. I was working on an RCA set and stuck a used crystal from a modern solid state set and it failed after a week. You can use the small crystal in this set. I have two of those style Zeniths running with new crystals.
Someone explained why the crystals go bad once in one of these threads. They called it 'silver migration', Where the crystal gets contaminated by the metals in the leads or something like that. A whisker type disease.
Its not just tv crystals. I used to collect EF Johnson CB radios and today the whole collection is a pile of dead radios. All 20 crystals in every radio is way off frequency and their hardly worth fixing. It would cost several hundred dollar to renew each radio with a set of custom made crystals.