Having issues with Ignition noise on my VHF Hi band radio. Have put a filter on the positive and negative wires and its still there. I have a 3db gain left fender mount and radio hooked to battery. VHF lo band has no such issue and as well hooked to battery. Tried moving antenna that didnt work.....Any ideas out there...Radio is a motorola PM 400,i have same set up in a 2100 dodge 1/2 ton antenna mounted on roof and no issues that radio is a CM 300.