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

Hubert v. Bonhorst hvonbonhorst at
Tue Apr 5 14:32:12 EDT 2005

there is some leak-current or offset in the integrating amplifier. Suspect
the amplifier itself as well. Try to do the integrating amplifier adjustment
procedure. Eventually modulator phase needs a little bit adjustment. Be
aware that a instrument connected to control output could cause a similar
effect. If you consider the specification. The 5061A is within limits.
Have fun

-----Ursprüngliche Nachricht-----
Von: time-nuts-bounces at [mailto:time-nuts-bounces at] Im
Auftrag von Poul-Henning Kamp
Gesendet: Dienstag, 5. April 2005 18:50
An: Discussion of precise time and frequency measurement
Betreff: Re: [time-nuts] 5061 Cs frequency shift with long time constant? 

In message <4252B46E.3010509 at>, Brooke Clarke writes:

>> 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.

Yes, very likely.  The leak-current in the integrating capacitor cannot
be fully ignored at this level.

Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.

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