[time-nuts] Improving the stability of crystal oscillators
John Ackermann N8UR
jra at febo.com
Wed Oct 10 14:33:55 EDT 2007
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
>> 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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