Hi TCXO’s are very different beasts than OCXO’s. In an OCXO, the crystal is not exposed to any significant temperature change.
Bob > On Jul 9, 2019, at 8:05 PM, Mark Goldberg <[email protected]> wrote: > > That is the dirty little secret of crystals. Manufacturers will test the > temperature response in one direction, but if you heat and then cool > crystals and measure the frequency, they do exhibit significant hysteresis. > I've not been able to get a supplier of TCXOs for me to characterize this > as I don't buy enough. I just have to test them myself and toss the 10% or > so that don't meet their specs due to the hysteresis. If you cycle the > temperature up and down multiple times, the effect lessens, but after > letting them sit for a while, it comes back. I also saw jumps at particular > temperatures, but that may be due to the TCXO compensation. > > Mark > > > On Tue, Jul 9, 2019 at 4:00 PM Glen English VK1XX < > [email protected]> wrote: > >> and non monitonicity in the device is the death of a control loops. >> >> My attempts at building good OCXOs using cheap AT crystals in the 90s >> was thwarted by.... non monotonic bending crystals ! >> >> And everytime they would wake up, the monitonicity would be in a >> different part of the control curve.... >> >> and they exhibited hysteresis, like defined steps , this seems to be the >> case with most crystals, the harder you looked, the more undesirable >> imperfections you found... >> >> >> >> On 10/07/2019 5:57 AM, David G. McGaw wrote: >>> Leo - >>> >>> I do believe you mean non-monotonic, rather than non-monotonous. Not >>> being monotonous is a good thing. :-) >>> >>> David N1HAC >>> >>> On 7/9/19 1:20 PM, Leo Bodnar wrote: >>>> It's not very good, it is highly non-linear and even wor >> >> >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. >> > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
