I think I have a acquaintance in USA that can maybe help but the
shipping is going to kill me to death..
More so than buying a bunch of never-ending projects?
One question -- it seemed that you had gotten to a place where the
(one of the?) 9390(s) seemed to be more or less working, but the Rb
did not seem to be very well disciplined, at least at short to medium
tau. I know absolutely nothing about 9390s of any vintage, but it
occurred to me to ask whether you're sure the GPS is used to
discipline the Rb in a 9390. Most of the telcom GPS/Rb units I've
seen are GPS-disciplined OCXOs with an auxiliary RB that is NOT
disciplined, but rather free-running, and used only for extended
holdover periods. Some of them correct for Rb frequency error to a
first approximation -- for example, I believe the Symmetricom units
with BesTime (e.g., TS-2500) monitor the Rb frequency as compared to
the GPSDO during lock, then correct the output frequency during
holdover (when the Rb is in use) by adjusting a DDS according to an
estimate of the Rb frequency error -- all without actually disciplining the Rb.
Just a thought. But, as I said, I have no knowledge of the 9390 so
this is rank speculation.
Best regards,
Charles
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