[Elecraft] [K2] Question about cheap and dirty signal tracing

[Kevin Cozens]

Greetings.

I have barely used my K2 going on about two years now. It seemed to work 
well when I first got it off the person who had assembled it. I got 
occasional comments about good audio when operating on SSB. I then 
started applying the mods to bring it in line with the post 3000 serial 
number units, applied the PLL stability mode, and replaced the crystals 
with a more closely matching set, and completely re-aligned the radio.

Since then, the radio seems to have become slightly deaf, and I also 
have some issues with transmit audio. I've considered selling it to 
someone who could fix it and starting over. Having acquired a good 
digital storage oscilloscope some months back, I'm going to have another 
shot at trying to fix the problems. I'll start by working on the receive 
issues.

I'm planning to get one of the Elecraft signal generator kits to help 
with tracking down the receiver issues. Since I don't currently have 
one, I'm starting with the cheap and dirty signal tracing notes from 
Tom, N0SS. I pulled out the KSB2 and disconnected the KAT2 to eliminate 
them as a source of problem. I have noticed one odd thing when using a 
random length of wire and touching one end of it to the indicated test 
points.

Touching the wire to either side of C6 (RF Board page 3), the S meter 
reading on the front panel goes up by about 2 LED's. What is odd is that 
if I touch W6, or either end of D6 (the previous and next points in the 
signal chain) I don't see this level of increase in signal level.

This isn't making sense to me right now. I would think I would get the 
same signal level increase at either W6, or D6, but not at neither point 
compared to both sides of C6. Could this indicate bad, or wrong value 
caps, for C5 and/or C7? Any other thoughts about this rather odd 
behaviour? Seems to be pointing towards something to investigate further 
but I hope I don't have to removed that bottom rear panel as its more of 
a pain to remove.