Maybe this is not "aging" you are looking at...parts in 10^9 over a few days sems a bit high for that (??) on a good quality crystal but I think you may find that is around the spec for the reference in the 1992. I never bother setting my (older Racals) counter to better than 1in 10^9 its good enough for the workshop, but I do measure them now and again and record the offset.
Alan G3NYK ----- Original Message ----- From: "John Green" <wpxs...@gmail.com> To: <time-nuts@febo.com> Sent: Wednesday, September 02, 2009 2:58 PM Subject: [time-nuts] OCXO aging behavior > I had always thought that crystals changed frequency consistently in one > direction as they age. That is until recently. I was trying to get the > reference in my 1992 as close as possible to my Z3801 and noticed that as I > adjusted the fine pot, there didn't seem to be a place where the frequency > stayed put. It seemed to drift lower over a days time. So, I thought I would > set it a little high and over the weekend it would go lower and closer to > the Z3801. Much to my surprise, I found it had gone even higher over the > weekend. I gave up on trying to get it so close and settled for around 1E-9 > or so. I am going to watch it over a few weeks to see what happens next. I > have also noticed something like hysteresis in frequency adjustment. A > little tweak in one direction can only be offset by a larger tweak in the > opposite direction. I assume all this is normal. I just had not been able to > see it until I started using a GPSDO to compare things to. After hearing so > much about how sensitive Tbolts are to temperature and antenna location, I > am going to feed both the Z3801 and a Tbolt off the same antenna and see if > I can see any differences. I don't know if I have the equipment for it, but > it should be interesting. > _______________________________________________ > 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.
