[time-nuts] Question on crystal jumps

[Rick Karlquist]

I'm not quite sure what the question is here, but when
we made 10811 oscillators at HP, "jumps happened".  Some
crystals were better than others, but no crystal was immune
from jumps.  With good quality crystals, you might be able
to put an upper bound on the magnitude of jumps, like 10-9,
but not on the time between jumps.  I also noticed that there
didn't seem to be any correlation between jump activity
and stability between jumps.  You could have an oscillator
with really low aging, say a few parts in 1E11 per day that
looked really good for quite a while, but then the frequency
jumps.  After you've controlled everything you can about the
crystal process, the electronics, the oven and the environment,
you are still left with jumps.  If you want no jumps, go to
an atomic standard like rubidium.  There are mechanisms that
can cause jumps in rubidium standards as well, but good
rubidium standards don't jump.

Rick Karlquist N6RK


iovane\@inwind\.it wrote:
> I would be very pleased to know when (date and time) anybody
> out there happened to record jumps in frequency of crystals.
> I have stable (e-07) tuning forks which happen to jump too,
> and I don't understand why, even having under control
> temperature and air pressure. Sometimes they return to their
> prior frequency with another jump, and this could happen even
> days later, sometimes they jump and then recover smoothly the
> prior frequency in a short time (such as one hour).
> I have no idea whether any correlations would exist between
> crystals and tuning forks jumps, regarding the causes that
> could trigger metastability, and hence I would have a look at
> crystal data in order to improve the base for future
> speculation.
>
> Thanks in advance.
> Antonio I8IOV
>
>
>
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