); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY This is something I have thought about but never did any experimentation. With the low cost and increased availability of thermoelectric coolers, I am interested in pursuing this concept. The unfortunate thing is that the crystals are ground for 25C or the higher turnover temperature point. If someone has a crystal that has drifted, it may be a good candidate for experimentation. Another thought would be to let the crystal operate at its natural frequency, divide it down to 1 or ten Hz and then phase lock a more convenient crystal frequency to the low pulse rate. The idea is to save an otherwise aged and well performing crystal.
John WA4WDL ----- Original Message ----- From: "Tom Van Baak" <[EMAIL PROTECTED]> To: "Discussion of precise time and frequency measurement" <time-nuts@febo.com> Sent: Monday, October 15, 2007 10:12 PM Subject: Re: [time-nuts] Improving the stability of crystal oscillators > As far as I can tell, temperature curve plots for quartz typically > show both an upper and a lower turnover point (for example, > see the pages below). Since the upper is well above maximum > ambient, it makes sense that this point is used in O[ven]CXO. > > The question is -- does anyone know if the lower turnover point > (LTP) is ever used? I ask because I heard that a quartz oscillator > might have slightly better short-term stability at the LTP compared > to the UTP. If so, this might argue for the extra trouble of using > TEC for cooling in some low-noise applications. > > /tvb > > http://www.ieee-uffc.org/freqcontrol/tutorials/vig3/vig3_files/slide0164.htm > http://www.ieee-uffc.org/freqcontrol/tutorials/vig3/vig3_files/slide0306.htm > > > _______________________________________________ > 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.