This weekend I ran some test at a portable site our club will use to
demo ham radio to about 50 youths.
We set up a Kenwood TS430, tuner and 20 meter dipole running on AC
power. I setup my KX1 with a
33 foot vertical with 33 foot counterpoise on the ground. A third
operator ran a DC-40 with a random wire
on the ground.
When I set up the KX1 I was copying a station in the MIQP near 7040.
Before I could call him I heard
a very load station on 7040 with lots of signal while key up. It was
the DC-40. After a short QSO, short in both
time and distance, I walked away from the rig for a few minutes. When I
returned the KX1 had no audio
out.
I tried 3 sets of earphones and also confirmed the phones were working
with another source. The KX1
didn't even have sidetone. I assumed I had a failure of the audio out
stage and suspected damage when
the TS430 tuned up at 100w on 20.
I packed things up and headed home where I checked the schematic before
opening the case. All that is
common to sidetone and receive audio is the last audio IC and volume
control. The XG1 showed a normal
S meter reading with 1 and 50 microvolts. With the cover off I started
touching parts around the input to the
audio amp listening for hum. I got hum at the input of the amp.
S meter and hum called for connecting an antenna. At first I was not
hearing much but over about 30 minutes
the receiver seemed to have recovered and I was able to work Tampa from
Jacksonville on 7026 with no problem.
I have been playing with electronics and radio for fun and profit for
well over 40 years. I don't like things that
'fix themselves.' Anyone have any ideas what might have happened?
Could a high RF level cause temporary
deafness? Keep in mind, this is a KX1 that landed 9Y0X on 20 after only
40 minutes. N6VX operating - I'll
never be that class DXer.
72 John
WA8KNE
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