[time-nuts] Improving the stability of crystal oscillators
wa1zms at att.net
wa1zms at att.net
Wed Oct 10 14:41:22 EDT 2007
Try DigiKey pn: 235-1123-ND for a simple PTC Thermistor that can be
soldered to the xtal case if one were so inclined. Do so at your own
risk to the xtal!
-------------- Original message ----------------------
From: John Ackermann N8UR <jra at febo.com>
> SAIDJACK at aol.com said the following on 10/10/2007 02:17 PM:
> > In a message dated 10/10/2007 11:13:21 Pacific Daylight Time, jra at febo.com
> > writes:
> >> We first built a small proportional heater circuit that we could shove
> >> in next to the crystal, and that worked OK. We finally found a source
> >> for thermistors spot welded to a spring clip that would mount snugly
> >> directly to the crystal case. With 12 volts applied, these heated the
> >> crystals very nicely. With the heaters, we were able to keep the
> >> systems running year round with about 1/10 the service calls.
> > Hi John,
> > interesting anecdote!
> > Would you know if the thermistors are still available? Who made them?
> We bought them as a replacement part from Yaesu USA. This data is 10
> years or more old, but here you go:
> Part Name Yaesu Part Number Murata Part Number
> Posistor G9090019 PTH507A01BG330N020
> They used to be about $7.00 each. Yaesu's parts-order phone number at
> the time was (800) 255-9237. I'm not sure if there's another source for
> the Murata part; back then, we couldn't find one.
> Amazingly, I still have a web page documenting all that we learned about
> those cursed radios, including the schematic of our original homebrew
> heater design: http://www.febo.com/hamdocs/d4art.html. The quality of
> the heater schematic isn't very good, but it's all I have.
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