Total posts : 45366
Also check the power supply!
When I temporarily couldn’t find my Talking House’s heavy transformer supply, I used a lightweight switcher supply, and on the Panasonic radio across the table, there were humming hash carriers all across the AM tuner! The radio was powered from the same strip as the TH. It was switching noise by carrier current probably.
Yes, even small FM transmitters can overload, the symptom for me was my signal being heard several places on the the band, like between stations and mixing with local full powered signals.
I had a scare from that, but here’s what to do for AM and FM, take a radio outside and see if the problem goes away, or try a car radio outside, if it’s clear, it’s gonna be clear for everyone else too.