[Elecraft] KX1 Please need help with T/R thump

[Don Wilhelm]

  Jerry,

Check the STL menu parameter.  If that is set to a high value (to 
produce a high level sidetone note) you may be hearing a "thump" just do 
to the high sidetone level setting.  O have heard that on several KX1s 
sent to me for repair.

OTOH, if that is not the problem, you might look at the mute transistors 
Q2 and Q3 to be certain they are connected properly (flat side facing up 
away from the board), and that R29 is the correct value (22K).

73,
Don W3FPR

On 5/23/2011 12:49 PM, Jerry W7ANM wrote:
> My KX1 has quite a noticeable and irritating "thump" or "plop" going back
> from transmit to receive.
>
> This "thump" has a  soft nature but seems rather loud and obvious. I have
> tried different headphones and it doesn't seem to help much. If I set the
> T-R delay to very slow, the side-tone is fine with no artifacts but when the
> delay times out and the rig switches back to receive there is the thump.
> Faster delay just makes it thump the same at each changeover to receive. The
> changeover from receive to transmit on the other hand is smooth and quiet.
>
> I built this KX1 a while ago and the thump has always been there. I always
> intended to ask the list about this but never got around to it and I thought
> I could live with it. After using my other QSK rigs, K2 included, and I go
> back to the KX1, I am reminded that the KX1 must have a problem and that
> this is abnormal.
>
> Has anyone seen a problem like this and found a solution? Any ideas on where
> or what to check?
>