[Elecraft] [KX3] JT9 Drift Problem

[Matt Zilmer]

Hi Jim,

You might want to run the temperature compensation procedure on your
KX3.  If it's performed correctly, you should see < 2 Hz drift over
the temperature range.  You may want to purchase the XG50, used as a
stable frequency referece, or you can supply your own.

The procedure is shown in this document:
http://www.elecraft.com/manual/KX3%20Custom%20VFO%20TC%20rev%20A9.pdf

73,
matt W6NIA

On Wed, 27 Mar 2013 18:43:01 -0400, you wrote:

>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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