Re: TCXO for U3S CPU clock #u3s #clock


HF
 

Okay, I have the TCXO ready.  I'll give it a try per Alan's suggestion.  But I just realized that calibrating it might raise an interesting issue.
For a while, I was using the U3S to transmit alternately on 2 different bands.  Then I resumed transmitting on just one band.  I noticed that my timing drift was greater when making 2 transmissions in a 10-minute period than it was when I only made one.  I guess this means that during a transmission, the CPU's internal clock doesn't increment the same amount as it does when not transmitting.  I suppose the internal clock raises an interrupt from time to time (so to speak) and during a transmission the interrupts have to be masked so that the timing of the transmission is correct.  Am I right?  Has anyone else noticed this?
The consequence I anticipate is that once I install the TCXO to run the CPU and measure its frequency ( I think I can get it within 4 Hz), entering its exact frequency into the software might not work.

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