[time-nuts] Why do crystals go bad?

Bill Hawkins bill at iaxs.net
Mon Feb 14 03:26:00 UTC 2011


Group,

Jim Garland on the boatanchors at theporch.com list asked about crystals:
"A 22.5MHz crystal (HC-5 case) in my homebrew receiver, built about forty
years ago, no longer oscillates. It seems to be purely an age-related
problem.
It is in a standard solid state circuit which bandswitches six crystals, and
the other five work just fine.  I wonder what causes a crystal to stop
working, and whether it is possible to repair them?  I've "repaired" dead
100kHz calibrator crystals, and hamband crystals in FT-243 cases, by
cleaning off the brass pressure plates, but am not sure if one can do this
on thin high crystals. As I recall, the metal electrodes are evaporated onto
the sides of the element. 73, Jim W8ZR"

One of the replies was:
"Broken families, drugs, drink... the normal, I suppose. John K5MO"

Scott Robinson asked: "Receiver crystals aren't getting beaten up by high
power,
but something has killed a lot of them in my R-390A and Drake R-4A.
Curiously yours, Scott"

And Roy Morgan asked:
"I have a 1960's frequency standard from a Nike site: the Sulzer Oscillator
and would like to find tech into on it."

Any help appreciated.

Bill Hawkins




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