In case anyone is interested in the Spectrum Lab software mentioned below, I found it here:
This is a very nice site - lots of goodies!
...Larry
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On Wednesday, October 30, 2019, 3:58:37 a.m. GMT-4, pgc1682@... <pgc1682@...> wrote:
Tcxo-s have long and short term drift. Short term drift better. Many precision time signal source available on shortwave. Easily measure drift if you have good ssb receiver and computer. Tune 1 khz lower or upper the tuner. With sound card spectrum analyser (for example free Spectrum laboratory) drift easy compute. If you worry sound card internal oscillator precision easy check with free sstv software msstv with time signal. Another way if you have two chanel oscilloscope and good reference signal simply check phase difference. If phase not sifted quickly, both generator frequency near same.
Now exactly know the error, simply correct matematically the compensation factor. If tcxo 25 000 000 and real is 25 000 100 hz simply use the corrected value.
Many amateur grade vna use this method.
Many chinese low cost tcxo-s fake. 0.5 ppm drift error not real many cases.
