[Elecraft] Calibration with CHU via Spectrogram Software

[Don Wilhelm]

Jim, Earl and all,

You are correct that directly measuring the 4.000 MHz oscillator is likely
to pull the frequency.

The solution is to use the method outlined in the manual - connect BOTH the
K2 internal frequency counter probe AND the external frequency counter to
the same point (TP3), then adjust C22 so that both counters display the same
frequency.  This method will assure you that the 4.000 oscillator is set as
close as the calibration and accuracy of your external counter will allow.

Using WWV or CHU or other standard frequency involves an interative
process - set C22, then run CAL PLL, check for zero beat, and do it again
and again until you have it right...  Using the external counter is much
easier and straightforward.   I guess you could fine tune to WWV or CHU
after doing the initial adjustment with the external counter, but if you are
within 20 Hz or so, I wouldn't bother for the K2 may drift as much as that,
and would make attempts at further refinement just an exercize in
frustration IMHO.

73,
Don Wilhelm  - Wake Forest, NC   W3FPR home page: http://www.qsl.net/w3fpr/
  QRP-L # 485   K2  SN 0020   mailto: w3fpr@arrl.net

*** Life is what happens when you're making other plans -- Mike Cross  ***

----- Original Message -----

> Tnx for the advice. Yes, I can use a freq counter but I'm afraid that
> connecting a probe will pull the freq. Can also listen for the 4.000 MHz
on a
> receiver but then its only as accurate as that receiver.  Perhaps this is
> good enough but people are talking about accuracy within 30 Hz or so. I'd
> like to use the method that has the best accuracy.  Seems like fine-tuning
to
> atomic clock accuracy at least theoretically is the way to go.
> Has anyone had good results with the CHU method?