I recently deployed a temporary simple indoor random wire antenna for 40 meters and just monitoring stuff. I gave it a quick try without a counterpoise and made a good QSO with it. I ran a simple counterpoise on the floor and attached it to my tuner. Worked better.
The addition of the counterpoise extinguished the radiation from another indoor antenna I use on 80 meters (magnetic loop). Even on RX it is apparent something has gone wrong. There is NO change in the loop's resonance or SWR.
The loop is connected to the direct/bypass coax 2 port, the random wire is connected to the random wire port and the counterpoise is connected to the tuners ground lug. If I disconnect the counterpoise, the loop comes back alive.
Everthing in the shack is connected to AC ground which in turn is connected to earth ground.
I've done a bunch of experiments grounding the loop at its feedpoint; nothing good or bad happens; even tried some ground screen experiments with no big deal changes.
Shouldn't an antenna that stops radiating because of a change made in a system have its SWR changed as well??
I disconnected the random wire from the tuner and the effect still existed.
Any comments or suggestions about all this?
The counterpoise is not in close proximity to the loop.