[Boatanchors] DX40 Mic input

[Dave Sublette]

Good morning,

I am restoring a DX40.  I see that from the mic connector on the rear panel
to the terminal strip at the input of the 12AX7 speech amp there is a 4
inch piece of small coax.  As wired originally, the shield of this coax is
only grounded at the end of the cable nearest the 12AX7.

Question #1)  I am replacing the rear mic connector with a two circuit 1/4
inch audio jack so I can add PTT.  I decided to replace the old coax with
new, probably RG174 (or is it 175?).  May I ground both ends of that coax
shield?

Question #2.  The reason I want to ground both ends is that I am adding a
shunt potentiometer from mic to ground at the rear connector to control the
mic "gain".  Actually it will be a mic attenuation.

The reason for the questions is I am trying to avoid introducing ground
loops.

What say ye?

Thanks as always, for your advice.

Dave, K4TO