try running a clean live from the battery.It cured the interference on mine.
why have you a live to the aeriel mount? shouldnt it be a negative earthI've got one to the aerial mount, had to do that to swr it
Could it be the patch lead ? , it used to run over the door top, got a bit rubbed and a slight kink.
why have you a live to the aeriel mount? shouldnt it be a negative earth
also you can get filters to fit in the power cable, i did this for my rotel on my tractor, cured the interfearence from the twin beacons
if your still struggling and are on the Wales trip bring everything along and pretty sure between us, we'll get it fitted