Well, to answer "What are they good for?" Really nothing. I have
rubidium and xtals locked to GPS and can easily get to 10e-12. With
some of the work I do, 1x10e-8 translates to "broken."

However, I also play with old radios, so why not have an "old crystal
calibrator" sitting warm on the work bench. I am kind of excited to
homebrew an oven. Temp sensor are easy these days. Or is that cheating?

That's why I posted to this group, not sci.electronics.design.

Just something fun to do while I am waiting for football to start again.

Steve.
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Steven D. Swift, , http://www.novatech-instr.com
NOVATECH INSTRUMENTS, INC. P.O. Box 55997
206.301.8986, fax 206.363.4367 Seattle, Washington 98155 USA