From: Hal Murray <[EMAIL PROTECTED]> Subject: Re: [time-nuts] questions on uncompensated crystal oscillators Date: Wed, 05 Jul 2006 13:02:00 -0700 Message-ID: <[EMAIL PROTECTED]>
> > > As I recall there is a hysteresis effect on the frequency vs. > > temperature curve that needs to be compensated for as well. - Mike > > Is there really hysteresis, or does it just look that way due to time lag > between where the temperature is being measured and that actual temperature > at the crystal? > > If there is, what's the mechanism? For any particular temperature, the crystal has an "optimal" distribution of mass when driven as an oscillator. When you change the temperature, you begin a process of mass movement, as you do that it changes frequency. The frequency drift continues over a long time and aging have been measured as a continous process over 5 years for a set of oscillators. For OCXOs you can avoid it at powerup by keeping the oscillator circuit turned off until the oven reached temperature. There are naturally other sources of aging. I'm sure certain members can both correct me and add much more knowledge. Cheers, Magnus _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
