Phonoland

I have a few older AM desk radios in my house that I enjoy listening to baseball on, but after adding dimmers to most of my lights, the interference is downright terrible if I have the lights on. When the lights are off, crystal clear.

I've tried some basic things like ferrite beads on the cords and antennas, but still lots of interference. I also tried using a ground cheater to create a ground for the ungrounded plugs.

Is there some way to cut down the noise, or isolate the radios from it? I'm willing to spend a few bucks on something like a power cleaner/UPS.

AM radio reception is PRONE to electrical interference.
It always was.... and always will be.
There is no magic bullet to eliminate it, other than shutting off the offending source, or moving to a mountaintop hideaway.

Guy's,
My Grandmother used to live on a street that had "streetcars"--man, you talk about "interference" !! ( and in those daze, for you youngins, there weren't nothin sept AM !! )
Also--I used to live on a mountain top--got it there too !
I have reduced it in this house by using all electronic dimmers/motor controls--but it is still here, to a lesser degree. One thing I did find while looking for the source of this--one of those electrical sockets with the "push-in" connections---seems that it was not "tight enough"--changed every outlet in the house to the screw-on, wire type. Ron Rich

See?
As I stated, AM is just prone to interference. - and always will be.

Lose the dimmers and unshielded CFL bulbs to begin with.

Yeah it's a problem. I am a radio collects, so I know what you're dealing with. A lamp with an incandescent bulb perhaps? it's not just dimmers and CFL's. My dishwasher is the worst.