[Bob F]

I recently acquired a 1994 Dodge Caravan with a pioneer supertuner AM/FM radio.
It has bad problems on an AM staion I listen to whenever I am near powerlines.
There is a 60 Hz hum that modulates the audio causing bad distortion. I thought
this would be a grounding problem, and have tried adding an additional temporary
ground at either end of the antenna cable, with no effect. Can anyone offer any
help in solving this?