My K3 developed an S2-3 noise level only on 160M. I was able to prove that this
noise was being internally generated by the radio and was not external. At
first, thought that it was being generated when the KSYN3 board for the
sub-receiver began to unlock...every time the PLL voltage ran out of lock range
the noise would start...or so it seemed. After servicing the offending KSYN3
board and solving the unlocking problem I also believed that I had solved the
mysterious S2-3 noise on 160M.
Unfortunately, even with the sub-receiver KSYN3 board now operating correctly,
the noise intermittently returned, usually when I was attempting to hear a very
weak DX station. Often the noise would begin very slowly after the radio had
been on for a few minutes, build and remain. Sometimes switching off the K3
and leaving power off for several minutes restored proper
operation....sometimes not.
Anyhow, I accidentally discovered (while working on something else under the
hood) that pushing on the aluminum plate to which the two KSYN3 boards are
attached would make the noise disappear and then come back, depending on which
way I applied pressure. I had found the problem!
I removed the board for the main receiver and cleaned all the contacts
(Elecraft suggests changing out the pins for gold plated types which they will
supply). I tightened the bolt holding the board to its mounting plate-it was
somewhat loose. I re-installed the board and tightened down both machine
screws after dabbing some NuTrol on the attachment points.
Problem gone! Now when I ground the main antenna connector the receiver is
completely quiet as it should be...no noise, no hint of noise...nada.
Bill VE3NH
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