[Elecraft] kpa100 causing K2 to be low on TX freq?

[email protected] [email protected]
Wed May 22 19:40:01 2002


John, KC4KGU wrote:

"I re-did it again today and for about 10 minutes, it was dead-on, every
band.  Then it drifted again.  Not as far but, it drifted.  It don't
think it is heat related because the K2 has been on in the shack for the
past couple of days with the exception of moving from the work bench to
the operating position which takes about 20 seconds.  When I did the
recal today and moved it back to the operating position, all buttoned up
and all, it was dead-on.  I wish I could figure out where it was going to
drift.  Once it does the initial drift, it is stable there.  If I could
calculate where it was going to drift, I would correct for it initially
and let it drift ON freq vs OFF freq."
==========
The drift is indeed caused by tempaerature changes.  One K2 owner came up
with a mod to cut the drift to about 33% of what it was originally.  You
can download his PDF file about the mod at
http://home.pacbell.net/johngreb/reducing_k2_frequency_drift.pdf .

Gary in support told me that the drift is mostly due to the analog BFO
circuit and that the drift issue is high on Wayne's list of engineering
changes to do this year.

My K2 #2622 drifts about 100 Hz from a cold start in the morning, where
WWV zeroes 9999.90 on the "dial".  It slowly drifts upward to where in
the afternoon (when it's warmer in the shack) WWV zeroes at 10000.00 on
the "dial".  It'll drift faster if you do some transmitting because of
the heat generated inside the cabinet by the PA transistors.  If you take
the top cover off after it's warmed up, WWV will appear to drift slowly
downward in frequency as the K2 cools down to ambient temperature.

73, de Earl, K6SE