[time-nuts] 5061 Cs frequency shift with long time constant?

John Ackermann N8UR jra at febo.com
Tue Apr 5 09:53:05 EDT 2005

This is very odd (I seem to be collecting these sorts of problems) and I 
wonder if anyone else has seen something similar.

I got my 5061A trimmed to the point where a 5 day run against GPS showed 
an offset of less than 1x10e-13.  I then switched the unit into the long 
time constant mode and now see that the offset (over 36 hours) is 
-1.7x10e-12.  Nothing else in the setup has changed.

It's hard for me to see how simply changing the loop time constant would 
change the frequency of the standard, especially by this much, but 
stranger things have happened.

Has anyone else experienced a shift like this when switching the time 



PS -- I was able to partially, but not completely, reproduce the phase 
shift that I wrote about a couple of weeks ago by jiggling the 1 PPS 
cable to the counter.  Replacing that cable seems to have resolved that 

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