[time-nuts] poor-man's oven

[John Ackermann N8UR]

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 <jimlux at 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)
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