Hi Any crystal in the vicinity of turnover point is going to be pretty flat. That relates directly to the way turnover is defined. There are some exceptions (10811), but the vast majority of OCXO designs operate the crystal very near the turnover point. The whole "chill it down" approach was tried quite a while back. The idea at least partially was to reduce aging. The ultimate conclusion was that the added complexity / reduced reliability didn't really get you any benefits.
Bob On Jan 29, 2013, at 3:15 AM, M. Simon <msimon6...@yahoo.com> wrote: > Those 32KHz watch crystals are very flat in the vicinity of the turnover. > They don't age well. But if all you need is temperature stability and you can > correct for aging a nice little electric heat pump (heats and cools) to keep > the crystals at around the 25C inflection point might be interesting. The > heat pump might not take too much power either. > > The temp error runs .04 (Tturnover - T)^2 ppm. i.e. .1 deg C from turnover > gives .0004 ppm freq change. That is .4ppb. if you can hold .03C (not too > difficult) you get 10X better - .04 ppb. Aging of course will be a killer > with respect to that. > > > http://www.iqdfrequencyproducts.com/app-notes/timekeeping/ > > > ====== > > Nice page on cuts: > > http://www.4timing.com/techcrystal.htm > > Engineering is the art of making what you want from what you can get at a > profit. > _______________________________________________ > 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.
