I have "clicks" in my house from similar thermal expansion and
contraction. It is most noticeable during the Winter season. The
KPA500 is similar, and it is not really a problem, just the consequence
of things heating and then cooling.
I would guess that the "clicks" could be eliminated by adding fiber
washers under the screws, but then the fiber washers would also expand
and contract resulting in loose fastening hardware. So my bottom line,
I would rather hear the clicks than be exposed to the possibility of
loose hardware.
73,
Don W3FPR
On 1/26/2014 6:16 PM, Sebastian, W4AS wrote:
I have noticed the same clicks with mine. I run mostly meteor scatter on 6
meters, which is somewhat similar to RTTY - long transmit times with a high
average output power.
After emailing Elecraft support on May 6th of last year concerning a failure of
my KAT500 tuner (which apparently had nothing to do with the amp’s noise), I
was told this was due to rapid expansion and contraction of the heat sink, and
even though it sounded like a relay, it was not necessarily coming from a
relay. What I found strange was that this noise didn’t occur until the amp was
several months old. I was offered the option to ship back the KPA500 in order
to track down the noise, and I did so.
After a few days, I received a telephone call from Elecraft with their analysis
of the noise. It was their belief that indeed the noise was coming from rapid
expansion/contraction of a metal piece in the amp; specifically what is known
as the Z-bracket. At the time I was told that a few other customers had
experienced the same issue, although none were in the US and mine was the first
they had the opportunity to look at. The Z-bracket was replaced with one of a
different metal composition, and I was told that several tests were run on the
amp and there were no other issues. I received the amp back and did not
experience the clicking noise at first.
A few weeks later, using the amp in the same manner I had before, the clicking
noise came back. Once again I contacted Elecraft support. Their response was
the same, the rapid expansion and contraction of the Z-bracket was what I was
hearing, and there were now several KPA500s which exhibited the same clicking
noise, but their conclusion was there was no damage caused by this. In
addition, there were no faults in the fault log.
I wonder how many others have experienced the same clicking noise, and if the
issue has been solved. While I accept their analysis, I still find it strange
that if the amp is on, yet I haven’t transmitted for several minutes, I will
still hear an occasional click.
73 de Sebastian, W4AS
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