Hi Tim, This is with the GPSDO that I designed. It uses a PLL which is corrected for sawtooth. The receiver is an LEA-6T. I've noticed that a few of these OCXOs continue to retrace upwards in DAC movement, even after a number of days. I haven't run any of them for more than a week, as I've built only a limited number of these units. The normal situation is to retrace downward from the start, once initial warmup is over.
Bob -------------------------------------------- On Wed, 2/10/16, Tim Shoppa <tsho...@gmail.com> wrote: Subject: Re: [time-nuts] OCXO Retrace To: "Bob Stewart" <b...@evoria.net>, "Discussion of precise time and frequency measurement" <time-nuts@febo.com> Date: Wednesday, February 10, 2016, 2:15 PM I think what you are observing, is the detail of how the control loop transitions from frequency locked to phase locked. And this has more to do with the divider chain reset and phase detector than anything else. Note that several of the hobbyist/E-bay GPSDO's (especially the "Chinese GPSDO") do not have a phase locked mode, at best they are frequency locked, and many of these have a consistent bias based on the gating of the frequency counter (typically their counter gating adds an extra count, meaning that when they are frequency locked to GPS they are running slightly slow). Tim N3QE On Wed, Feb 10, 2016 at 2:17 PM, Bob Stewart <b...@evoria.net> wrote: I've been running up a number of OCXOs lately, all Trimble 34310-T. For most of them, the DAC moves in the negative direction after lock. But there are a few where the DAC moves more positive. Is this an indication of a different cut of crystal, or is retrace direction more or less random? Bob - AE6RV _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.