I need some help the my H1's radio reception. Its a after market radio that for the past 6 month has a very loud screech (starting low and slowly rising high and then back low) and not all the time. some time the radio is crystal clear.
I have replaced the antenna and put a power booster on the incoming antenna line. Still have the screeching any ideas

 

Does the high-low noise correlate with engine revs? That can be common with aftermarket electronics of any type. It doesn't sound like reception to me - it sounds like a radio problem.

 

Check your grounds, not sure how its hooked up. If you're using something like a wiring harness I would get the ground from the head unit to the wiring harness and reground the head unit to metal somewhere behind it.

Wiring harness grounds just suck.