TCXO drift and calibration

Posted by Gary Peterson on Dec 04, 2019; 8:33pm
URL: http://elecraft.85.s1.nabble.com/TCXO-drift-and-calibration-tp7656815.html

Last February, I purchased a factory assembled K3S including a 1 ppm TCXO.  The transceiver is serial number 11803 and the firmware was updated on May 5th of this year.

Last July, I noticed that many of the signals on 50.125 MHz sounded as if they were a bit off frequency as they were higher pitched.  This led me to believe that the reference oscillator may have drifted, possibly due to crystal aging.

Subsequently, I used method 2 and WWV, as described on page 53 of the Elecraft K3S manual.  The REF CAL frequency was lowered from 49.999.996 to 49.379.448.  That seemed to make the signals on the 6 meter calling frequency sound like they should.

A few days ago, I caught a six meter opening and signals on 50.125 sounded higher pitched again.  I repeated the reference oscillator calibration again, using method 2.  Now, the REF CAL frequency is set to 49.379.110.  I have not had the opportunity to hear any six meter signals, since I changed the reference oscillator.

I am wondering if the REF CAL frequency change that I have seen in less than a year is normal, or whether I have a TCXO problem.

Any thoughts would be most appreciated.  Thanks in advance for any time taken to reply.

Gary, K0CX
Rapid City, SD
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