We did this years ago on a 430 MHz data radio with an utterly uncompensated crystal that would drift through the passband. After building our own for a while, we discovered that Yaesu had something even better available through their replacement parts shop -- a spring clip with PTC that snapped tightly over the crystal case. I never did any formal measurements, but it did improve stability quite a bit for radios that were sitting in uncontrolled environments.
John On Jun 4, 2017, 8:18 AM, at 8:18 AM, jimlux <jim...@earthlink.net> wrote: >I recall some years ago folks were talking about putting a PTC >thermistor on the TCXO of a FlexRadio SDR1000 to stabilize the >frequency >as a sort of poor-man's OCXO. >It's also referenced at >http://www.setileague.org/askdr/xtaloven.htm >where he says "order of magnitude improvement" with no numbers (from 1% > >to 0.1% or from 1 ppb to 0.1 ppb?) > >I wonder how well that actually works. > >Say you bought an inexpensive (perhaps non TC) XO and an equally >inexpensive thermistor, glued on on the other, hooked em both up to 3.3 > >or 5V. > >Yeah, there's issues with room air blowing on it, and tolerances in >both >the XO and thermistor, so your absolute frequency accuracy may not be >so >hot. But what sort of medium to long term performance can one expect. > >I did some searches, because I'm sure we've discussed this before, but >I >couldn't find it. There was some stuff from Oct 2007, but that was in >the context of a more complex circuit, and the thermistor was the >sensor. (discussions of TE devices too) >_______________________________________________ >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.