[Elecraft] KPA500 Clicks

[Don Wilhelm]

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
>