[Elecraft] [K1] Internal Noise Bursts every 12 seconds or so

[Bob]

Many thanks for the rapid reply, Don!

Good to know this isn't normal, and I will certainly follow your advice and
check the front panel assembly carefully, especially the solder.  When I
initially checked things with an optical loop, the solder appeared to be
bright on both sides of the PCB (at least for things I could see).  I did
use a 700 degree tip on my Weller WTCPT Iron and standard Kester 44 solder,
so the potential for decent soldering is there at least.

Even though the second CPU on the filter board is mostly inactive, no
telling what internal loops are going on that might result in it turning
that 4 MHz resonator into a periodic signal.  So I'll be sure to check
around that too.  Of course at this time in the assembly process, the
Filter Board is not screwed down.  Don't know if that is a source of noise
or not.  I'm also curious what the AGC_OFF signal is doing on that board.
I'll investigate that later.

Given that it is appearing in the audio chain (or at least post
demodulator), I am suspecting the noise is propagating over the internal
power rail.

Figures I'd have an interesting problem.

Thanks again!

73, Bob, WB4SON