[time-nuts] Cheap 9.8Mhz Sa.22c's

Charles P. Steinmetz charles_steinmetz at lavabit.com
Thu Jun 6 00:39:05 UTC 2013


>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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