I have a K2 that I have been using for almost a year on JT65. No
problems whatsoever. I obtained WAS and eWAS in about 4 months of casual
operating.
A few months ago I got a KX3 and for the last few days have been trying
it out on JT9. I haven't been able to make a single contact. I would
call CQ and see someone answer me on the same frequency but WSJT-X
wouldn't produce a decode. I could answer a CQ and see a reply but again
no decode. (I was running 5 watts.)
This afternoon I noticed something unusual. After a 1-minute
transmission all of the received signals during the next minute had a
skew (drift) and none decoded. The drift was for a total of about minus
ten Hertz during the minute after the transmission. If I didn't transmit
during the next one-minute cycle there was little drift and the received
signals would decode.
I began to speculate that during the one minute transmission some
temperature-sensitive component(s) heated up and caused a change in
frequency. During the next minute they cooled and the frequency returned
to normal. I played with this for a little while and the results were
consistent. In the minute following a transmission there were no decodes
but during all subsequent minutes signals would decode.
I switched back to the K2 and had five normal JT9 contacts, the nicest
of which was John, ZD7JC on St. Helena Island in the South Atlantic. All
this with a low dipole and 10 W. (He gave me a signal report of +00
which meant that I could have been using one watt or less.)
I assembled the KX3 and believe that I ran all the tests and
adjustments. Any suggestions as to what I can do to tame this
temperature sensitivity?
73,
Jim - W4BQP
K2 #2268, KX3 #2875
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