[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!

-Brian


-------------- 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.
> 
> John
> 
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