[Elecraft] K3 mechanical problem

[Ron Kenwood]

I have completed my K3/100 to the K3/10 stage. All of the functions 
appear to work well. My only problem is an intermittent crackling noise 
in the receiver that runs between S5 to 7 with no antenna connected. It 
is definitely mechanical in origin and I believe I have isolated it to 
the connections between the RF board and the front panel.

The noise usually occurs when powering up. I took off the top cover and 
found that I could stop the noise by pressing the RF board in the area 
of the roofing filters, forward to the front panel. Once it is gone, it 
seems to be gone for that session with the radio.

I buttoned up the radio. The next time the noise occurred, I went to 
take off the top cover and accidentally started to unscrew a screw on 
the upper lip of the front panel. The noise stopped. This is reproducible.

When building the radio, I do remember that putting in the screws on the 
bottom lip of the front panel took a significant amount of pressure to 
line up the front panel holes with the 2D connector. I have inspected 
the edge connections as best I can and they appear to be well seated. I 
have checked the two vertical boards on the rear of the shield and they 
appear to clear the shield, and do not affect the noise when pressed.

I contacted Elecraft support and they were sympathetic but I couldn't 
reproduce the noise while they were on the phone so not much was 
accomplished.

Finally my question. Do I need to tear down the radio and reseat the RF 
board to the panel or is there an easy way out, or another possible culprit?

Ron W3ZV