http://www.abracon.com/Resonators/AB26T.pdf
This quotes .038 ppm/C^2 delta T from the turn over point: http://www.iqdfrequencyproducts.com/app-notes/timekeeping/ The fly in the ointment is the aging rate of 5 ppm the first year (13ppb/day) and 3 ppm (8ppb/day) after. I'm sure holding 1 degC is easy. .1 C with some care and .01 C - my measuring eqpt ain't that good. So temperature ceases to be a problem. Is the other stuff workable? I would go with a 32KHz crystal for a "production" version to make it easy to multiply up to 10MHz. Simon Engineering is the art of making what you want from what you can get at a profit. >________________________________ > From: Tom Van Baak <t...@leapsecond.com> >To: Discussion of precise time and frequency measurement <time-nuts@febo.com> >Sent: Wednesday, December 12, 2012 3:55 AM >Subject: Re: [time-nuts] Stable Watch Clocks > >> Typical 32KHz clock crystals are very stable in frequency if you can keep >> them >> close to the turnover temp. If you can hold 1 degC it is .04 ppm. > >That's far better than I thought. Do you have a reference for this spec? > >I agree you might be able to make one accurate to 0.04 ppm, however briefly, >but I've never seen one stable to 0.04 ppm. I mean, that's like 1 second a >year. > >> I currently have no method for testing such a rig for stability. > >Oh, the slipperly slope you are on. I have just the solution for you ... > >/tvb > > >_______________________________________________ >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.
