[NLRS] shack local noise issue - 2M - help?

[Bryan LaPlante]

Well, tried to work some meteor scatter this morning and finally got fed up
with the high background noise levels I have.  So, started to do some
isolation work and found something that has me a bit puzzled.

With an audio power meter, no antenna connected, set audio gain so that I
read 0dbm of noise from the speaker.

Add my first section of coax (RG 8x, commercial jumper, 1 foot long) - no
change in noise (left unterminated)
Add my second section of coax (RG 8x, my connectors, another 1 foot long) +
3 db increase in noise with a commercial shielded 50 ohm termination at the
end.  Worse if unterminated.  Huh?

What I'm finding is that with the two sections of cable, this 2 foot cable
is acting like an antenna (despite the 50 ohm terminator), and picking up
background noise, birdies, etc.  Of course, this is a 'shack' so there are
lots of local sources - PC, power wires, etc. nearby.

I'm astonished!  Each connector should be maybe a .1 db degradation, and RG
8x isn't great, but 1 foot of it is nothing.  From theory, I should be
seeing maybe 1 db of added noise.  I have checked the coax for continuity
and shorts - checks fine.

I'm thinking what is happening is that signals are coupling onto the shield
of the coax, and then somehow coupling into the rig.  The rig is a kenwood
TR751a 2M all-mode.

Note - I don't have the rig connected to a station ground.  The station is
on the 2nd floor, and from what I've read it isn't really practical to
provide an effective station ground at this frequency over that distance.

Suggestions?
Hardline?
Move the shack to the basement?
Install a station ground and only work 10M and lower?
Stamp collecting?

KB0OBT - Bryan