Batboard

I just installed a med power UHF into a car that had a A-7 unit, I used all same power lines and speaker but now on recieve the radio has a little whine/tickle noise in it sometimes. I have looked at it on the service monitor and nothing. It is clean on transmit. I was wondering if the extension cable for the HHCH could be more suseptable to computer noise in the car? It is a 2001 Mitsubishi Galant.

Thanks
Stan