[Elecraft] K3: Relay noise?

[Classe Bergman]

I have heard this relay noise since I put together my K3 kit s/n 1484 in
August 2008. I always use full QSK, and then it's easy to hear the clicks if
the room is silent.
I was little surprised in the beginning, as I had read that the T/R
switching should be all electronic. I didn't think no more about that, as I
have KPA100, KAT3 and KXV3 installed I thought that there was a small relay
somewhere on the options modules.

Today I did some tests, and took the top cover off and tried to listen
carefully after the clicks. I am sure that it comes from a relay located
somewhere under the KPA100 module. Not from KAT3 or the LP filter relays.

There is no change in clicks if I put the radio in TX TEST mode or have full
RF output, so it is not RF or high current related.

It very hard to hear if I close PTT or a key manually or tap XMIT, but it is
still there.

CW mode , SSB mode or KPA100 disabled, it is still there every time T/R is
switching.

After a quick look at the K3 LPA schematic, I can se a small relay K1, "3 dB
attenuator".  What is that relay doing ? Can that be a candidate for causing
the noise? 

I have just done the same tests with an other K3 that was factory build.
Both radios produces exactly the same relay noise.

I am using the lastest software in the radios now, but it have been the same
thing with older software.

73 Classe SM3GSK