Bowmoreman
500+ Head-Fier
Yikes. You’ve run the gamut of my ideas at this point (until very recently in my major system reconfiguration, I used ferrite cores around my phono cabling religiously.) No longer need them with entire system fully isolated and star grounded on ONE dedicated circuit via the Tice Power gear. And, I live out in the sticks so minimal RF around…Yes,
I did the ferrites. Graham Slee has interconnects with the ferrites in the them. I also tried their Accession MC and Enigma PSU which both have filtering (at the same time as the ferrite cables). This attenuated the radio signal (AM), but did not eliminate it.
The only measure I have not done is the cage around the TT while playing or trying aluminum over the tonearm cable.
Must be a HELLA powerful am signal… wondering out loud, Salamander AV shelving equipment makes shelves where the sides and back are a perforated metal mesh, which might give you a close approximation of a Faraday cage to surround your TT. (You could for example have grounding wires on the sides, and maybe put a flat piece of metal on top also grounded to build out a TT-sized grounded “cage”.)
Thinking “outside the cage” as it were…
Good luck