radio interference

I have fitted a new stereo and although listening to cds is fine, I get a lot of feedback from the engine when listening to the radio (especially AM for some reason) the aerial is a standard one mounted on the back wing. The car is an old c-reg 1986 318.

can anyone help?

I have fitted a new stereo and although listening to cds is fine, I get a lot of feedback from the engine when listening to the radio (especially AM for some reason) the aerial is a standard one mounted on the back wing. The car is an old c-reg 1986 318.

can anyone help?
yes there are filters you can buy to reduce engine whistle. or buy a good pair of no noise rca cables . the new cables worked for me.