Hello Scott, this means the gain is set too high so that there is not enough phase margin. You can try to set the serv:dacgain lower, and serv:efcs / serv:phaseco lower. Contrary to OCXO's, Rb's are quite stable so they don't need strong control, they just need a gentle nudge, so you can try starting with low numbers. Let me know if that works, bye, Said In a message dated 4/8/2008 21:31:50 Pacific Daylight Time, [EMAIL PROTECTED] writes:
I've found that once the units gets into an overshoot/oscillation cycle it never recovers and I have to manually adjust the dac to break the cycle. Is the notion that you use conservative enough settings so that this never happens? Scott [EMAIL PROTECTED] wrote: > Hi Scott, > > let me reply on this list since other users are also using Rb's. > > Here is a quick pointer: > > 1) determine EFC slope of Rb (pos = frequency goes higher with higher EFC > voltage). Set the slope with serv:efc:slop [positive/negative] > > 2) Determine maximum frequency deviation at EFC = 0V (serv:coarsedac 0) > using a frequency counter > > > 3) Determine maximum frequency deviation at EFC = 5V (serv:coarsedac 255) > > > 4) Set Dacgain according to table in user manual depending on the frequency > difference between 2) and 3) > > 5) Set Integral part of loop to zero: serv:phaseco 0.0, this helps for now > > 6) Set Proportional part of loop to a number that makes the unit lock as > quickly as desired without oscillation and overshoot (for example: serv:efcs 1.0 > to serv:efcs 6.0 > > 7) Set the integral part of the loop so that the phase is driven to 0ns UTC > offset as quickly as desired without overshoot/oscillation, for example: > serv:phaseco 20. > > Repeat 6) and 7) after some hours. > > Hope that helps, > bye, > Said > >> -----Original Message----- >> From: Scott Mace >> Sent: Saturday, April 05, 2008 17:51 >> To: Said Jackson >> Subject: Re: Fury GPSDO >> >> >> Said, I finally got my fury up and running, I'm using a efratom >> FRS-A and also a LPRO-101. >> Do you have any recommending starting points for tuning the servo >> for a rubidium unit? >> >> Scott >> > > > > > **************Planning your summer road trip? Check out AOL Travel Guides. > (http://travel.aol.com/travel-guide/united-states?ncid=aoltrv00030000000016) > _______________________________________________ > 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. **************Planning your summer road trip? Check out AOL Travel Guides. (http://travel.aol.com/travel-guide/united-states?ncid=aoltrv00030000000016) _______________________________________________ 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.
