[Elecraft] KPA500 clicking

[Robert Friess]

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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