); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Hi Tom:
That's a cleaver improvement to a non ovenized crystal. Usually crystals are ground to have a temp vs freq turnover point occur at a specified temperature. The common one is to be on frequency at room temperature. So if a room temperature crystal is heated it's no longer operating at the turnover temperature and so there is a steep delta frequency vs. temperature slope. Did you get a crystal cut for your heater temperature or somehow match the heaters temperature to a turnover point on your crystal? I spent many many hours adjusting the oven temperature of a Gibbs frequency standard to get it right on the turnover point. Since the improvement in frequency stability depends on minimizing the temperature excursions it's good to have as much gain as possible in the heater feedback circuitry. This was done for the HP E1938 10 MHz oscillator, see: http://www.prc68.com/I/HPE1938.shtml and the paper: The Theory Of Zero Gradient Crystal Ovens, R.K. Karlquist, L.S. Cutler, E.M. Ingman, J.L. Johnson, T. Parisek Have Fun, Brooke Clarke, N6GCE http://www.PRC68.com http://www.precisionclock.com http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Cam Tom Clifton wrote: > ); SAEximRunCond expanded to false > Errors-To: [EMAIL PROTECTED] RETRY > > While the website is not explicitly about frequency > measurement, there is an interesting bit on improving > the stability of crystal oscillators with external > heater controllers. While it may not be suitable for > long term high stability control it might be suitable > for many other purposes. > > http://www.qrss.thersgb.net/Crystal-Ovens.html > > The main page is also a good read: > > http://www.qrss.thersgb.net/Receiving-QRSS.html#Introduction > > > > > > > ____________________________________________________________________________________ > Need a vacation? Get great deals > to amazing places on Yahoo! Travel. > http://travel.yahoo.com/ > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
