[Elecraft] KX1: new build & transmit problem on 20m ...

[zendoc at netspace.net.au]

 Hello Group,

I've just completed building KX1 # 2644, including the KXB3080 module,
and have discovered a problem.

All progress testing and alignment proceeded smoothly to the end of
both manuals.  But I've noticed that when listening to the KX1's
transmitted signal (using my K3 as receiver) on 20m only is very
raspy.  It sounds distorted, with what sounds like another signal
lower in frequency.  In fact, it sounds a little like that low
frequency buzzing you hear when you grab the audio plug connected to
the input of an audio amplifier.

Here's what else I've found:  this is present on 20m only.  The tx
signal on all other bands sounds very clean.
When switching between the bands, I can hear relays clicking for all
band transitions EXCEPT switching between 30 and 20m. No clicking
there.
RF gain control is much less effective on 20m, compared with other
bands.
20m receive is basically OK, but maybe a little less sensitive
(subjectively) compared with other bands.

Not sure where to start with this, so any advice much appreciated.

73,
John 
VK7JB