[Elecraft] Frequency calibration points

[k6se@juno.com]

Lenny, W2BVH wrote:

"I made 2 checks on my K2  (sn1520): One on CHU at 3330.00 and one on WWV
on 10000.00 KHz.      I did the check in cw mode, matching (by ear) the
CHU/WWV carrier note to the K2's internal sidetone, looking for the
slowest beat  note I could. I'd estimate the beat note was 10 Hz or less
in both measurements.

The results are:
         1. for CHU, my K2 reads 3330.05 (or 50 Hz higher than CHU's
actual transmit frequency)

         2. for WWV, my K2 reads 9999.91 (or 90 Hz lower than WWV's
actual transmit frequency)"
==========
The frequency calibration accuracy highly depends on the temperature of
the rig at the time you measure it.  WWV and CHU will appear to drift
upward in frequency from a cold start until it stabilizes after a warmup
period (if the temperature of the environment is stable).

My K2 originally was out of the 100 Hz drift specs given by Elecraft.  I
replaced the PLL ref osc xtals which they provided, and now the drift is
about 90 Hz, just barely within specs when the ambient temperature is
stable.  If the room temperature varies (as it does in my shack from
morning until afternoon), the drift will be greater and more noticeable.

The 4 MHz xtal oscillator on the control board should be set as closely
to 4000.000 kHz as possible using an accurate frequency counter or ham
receiver.  With that oscillator adjusted precisely to 4000.000 kHz, my K2
will read WWV at about 9999.90 in the morning (shack temp about 76F) and
it will drift up to about 10000.06 in the afternoon (shack temp about
80F).  On a very cool morning (about 68F), WWV will zero at 9999.80 kHz.

When the temperature is just right and WWV zeroes at 10000.00 kHz, they
are also zeroed at 15000.00 kHz and 20000.00 kHz.  The third harmonic
(1830.00 kHz)  of a local BC station on 610 kHz is also exactly on
frequency.

While the K2 is an outstanding piece of gear in most other respects, I am
highly disappointed that such a quality radio fails miserably as far as
frequency drift goes.  This might not mean much to some, but it means a
lot to nit-pickers like me.

While the KI6WX frequency drift mod may alleviate this problem somewhat,
I feel that the problem should not be there to begin with and it should
not be necessary to modify the radio to make it drift less.

Hopefully, Eric and Wayne will do something about this major problem with
the K2.  If I were to write a review of the radio, I'd rate it highly in
all respects except for frequency stability, where it would rate a zero.

73, de Earl, K6SE
78 countries with K2 #2622 and counting.....