John, Yes, I have changed the gain to exactly your suggested -0.2 V/Hz and I have experimented with the damping from .5 to 3 and I'm currently using 1.00. Things certainly change with various damping and TC settings but not nearly as slow and subtel as I would like to see for an oscillator like the 10811. On the Fury I am using DACG=250, EFCS=.8, EFCD=80 and PhaseCO=12 (favoring freq stability for 10MHz reference). On both configurations I typically see 3.1 to 3.3 nSec standard deviation so still much better than a Z3801. Regards... Don
________________________________ From: John Miles <[email protected]> To: Discussion of precise time and frequency measurement <[email protected]> Sent: Monday, July 13, 2009 3:32:37 PM Subject: Re: [time-nuts] Trimble Thunderbolt setup optimization and addinga10811 OCXO What are you using for the Kvco constant with your 10811-based Thunderbolt? If you don't back it down to -0.2 V/Hz, the loop's damping factor will be very wrong, which might confuse the firmware. Check the Kvco, and also do a factory reset after changing the OCXO to make sure it forgets anything it might be remembering about the OEM part. (You might try that, too, Arnold.) -- john, KE5FX > -----Original Message----- > From: [email protected] [mailto:[email protected]]on > Behalf Of Don @ True-Cal > Sent: Monday, July 13, 2009 1:15 PM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] Trimble Thunderbolt setup optimization and > addinga10811 OCXO > > > Arnold, > > I have the same question as well as observations as yours. I have > been working with both the TBolt and Fury connected to two > different 10811s. With either the TBolt or Fury, I can't get the > TC large enough to only provide a nudge to the EFC every few > minutes. Both receivers get real unstable and cause large Freq > and PPS swings with large TC numbers. It seems the EFC is > providing many corrections per minute even with the TBOLT set to > 300 secs. Anything larger than 300-500 sec. on the TBolt and > EFCD=150 (don't know what the equates to in secs.) on the Fury > will cause instability. I have better luck disabling desciplining > on the TBolt or disconnecting the antenna on the Fury (no command > to disable that I have found) when I need to do a Tau 0.1-10 sec. > low jitter measurement. > Regards... > Don > > > > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
