[Milsurplus] BC-221 temperature compensating capacitor question -

[RICHARD SOLOMON]

Before digging into the oscillator, first I would ask how you are measuring
the frequency and how good is the reference oscillator of the measuring
device.
If your frequency counter has an external reference input (hopefully 10 MHz),
then you can easily make a GPS Disciplined Oscillator that will suppky an
external reference that is far more accurate than almost anything else.
(It is derived from the Cesium Beam Standard on the GPS satellite).
With such a device one can accurately measure to within 10 Hz at
10 GHz, sometimes even better.
 
73, Dick, W1KSZ> Date: Thu, 22 Jan 2009 19:07:27 -0600> From: olegerityincj at austin.rr.com> To: milsurplus at mailman.qth.net> Subject: [Milsurplus] BC-221 temperature compensating capacitor question -> > Oh grand wizards -> temperature compensating capacitor question> The BC-221-AK 1000Khz reference Oscillator has been observed starting > about 220 HZ high, 4000.220KHz on cold start 4000.220 KHz then after > about 2 hours of warm-up drifts down to about 20 Hz below 4000 KHZ at > measured 3999.080 KHZ end of high band. This found by finding the zero > beat taking a frequency reading on the Freq counter then doing the same > process periodically over a 2 hour period. 240Hz swing so far.> > The temperature compensating coils are clean and can move freely, so > that is not the problem.> > Is this the norm expected considering the period in which the unit is made?> > If not what considerations and procedures would I use to re-compensate > for the temperature environment.> > Thanks> Hutch> > > ______________________________________________________________> Milsurplus mailing list> Home: http://mailman.qth.net/mailman/listinfo/milsurplus> Help: http://mailman.qth.net/mmfaq.htm> Post: mailto:Milsurplus at mailman.qth.net
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