[Elecraft] KX3: thermal frequency drift

[Edward R Cole]

It was suggested I do the Temp Compensation Procedure.  Unfortunately 
I do not have a stable 50-MHz signal source. However I did run the 
Reference Frequency Calibration using my XG3.  Call this "Part Two":

I sampled the RF output of the XG3 with my counter and also input 
that to the KX3 for the Calib.  This required running at 0 dBm to 
inject strong enough signal for the counter (approx -3 dBm).  I 
turned on the ATT for the KX3 to keep input from overdriving.  Got 
about S9 signal level.

I got it adjusted to within about 2-Hz.  The XG3 drifts approx +/- 2 
Hz so difficult to set the Ref*Frequency using it.  But that 
eliminated most of the 38 Hz offset I saw last night.  Running the Tx 
at 5w afterward drift was in the range of 0 to +7 Hz for a 50-second 
key down run.  The drift is not steady in one direction so average 
error is probably in the neighborhood of +5 Hz with 5-Hz uncertainty 
in the measurement.  Crude but gives a ballpark idea what to expect.

Today's measurements were all with new heat sink installed.  Temp 
Comp. probably would lower these numbers a bit.

I might try running my K3 as signal source for Temp Comp. if it holds 
more stable then the XG3 at 50-MHz.  I am using the EXREF so it may be better?

73, Ed - KL7UW
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