[Elecraft] K2/100 RF gain knob inoperable

[Mike Seiffert]

Hi Folks,
I have an Elecraft K2/100 (S/N 01136) given to me by father (SK) some years ago. I am finally finding some time again for ham radio and would like to get this rig up and working well.  It has the A to B mods applied, and includes the options for SSB, DSP, 160/Rx ant, etc. I have applied the BFO and PLL upgrades.

My current problem is that the RF gain knob doesn’t seem to do anything. I was expecting to hear some difference in the level of received signals and to see the S-meter go to the right as I turn the knob fully CCW. Turning this knob seems to have no affect on anything. 

Any help would be appreciated!  I mention the following details in case they are relevant: my father was mostly interested in 160m cw, so I’m not sure if other aspects of the radio received attention when he built it. The AF gain knob is scratchy - I’ve read about the mod that addresses this, but haven’t yet applied it. The AGC needs adjustment - I can tell the difference in volume AGC On vs off with no antenna connected. I don’t know that any of these are related to the RF gain. 

Before I open things up to measure and replace the RF gain pot, are there other things I should check?  A quick check of the email reflector archive didn’t turn up anything obvious to me. 

73,
Mike AE6NH