I have an ASH26E with no radio noise problem. I also have a Cambridge 302.
When first installed, there was some noise coming from the 302 on a couple
of radio frequencies, enough to break the squelch anyway. Ferrite beads on
the radio and Cambridge wires took care of the problem.

I agree with the advise already given, re using a hand held radio and
disconnecting stuff to isolate the problem.

bumper