[Elecraft] KPA500 clicking

[Jack Brindle]

Make sure the big toroid power transformer is tightened down properly. The tendency is to avoid tightening it too much, fearing some damage will occur. The transformer needs a bit more than that. I'm sure you will get a better feel for it shortly.

- JackB, W6FB

Sent from my iPad

> On Dec 31, 2014, at 7:45 PM, Wes (N7WS) <wes at triconet.org> wrote:
> 
> Bob,
> 
> Thanks for your answer.
> 
> Hopefully, it lays to rest the idea that I didn't know what I was talking about when I described it as the sound of a reed relay following the key.
> (Hmm, mechanical motion initiated by electromotive force....sort of describes a relay doesn't it?)
> 
> That said, I'm not sure the phenomenon is totally due to magnetostriction. "Coil Noise" may be a better explanation. (http://en.wikipedia.org/wiki/Coil_noise)
> 
> In the case at hand, I'm a bit concerned about having this happen.  Perhaps it's from spending too many years around a failure analysis lab or doing vibration testing on assemblies, where with a strobe light we could watch things move to the point of failure.
> 
> What is Elecraft's fix?
> 
> Wes
> 
> 
>> On 12/30/2014 12:29 AM, Robert Friess wrote:
>> What you are hearing is due to magnetostrictive force causing the windings
>> of the inductors in the TR switch to bang against their cores as the TR
>> switch bias is applied.  There are no relays.
>> 
>> 73
>> Bob, N6CM, KPA500 design engineer.
>> 
>> On Mon, Dec 29, 2014 at 10:23 PM,<mcduffie at ag0n.net>  wrote:
>> 
>>>> RF may be switched with PIN diodes, but there are some relays in there
>>> someplace.
>>> 
>>> No TR relay.  Amp is quiet as a mouse when keying/unkeying, even in QSK.
>>> There
>>> IS a STBY/OPER relay, I assume, as I can hear it when I go in and out of
>>> OPER.
>>> Also, band switching, of course.
>>> 
>>> There are ticks due to heating in the heat sink, but not in time with
>>> keying.
>>> Random, and varying rate.  Documented on this group previously.
>>> 
>>> Have you asked Elecraft (not this list) for a diagram?
>>> 
>>> Gary
>>> 
> 
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