"Colin" wrote in message ...

Thanks for the thoughts, Eric - I did as you suggest, there was no
difference. As noted, if I switch to grid power the interference is gone.
However the solar array is still sending a charge to the controller at
this
point, so if it was simply RF noise from something in the 'solar chain'
the
noise should persist even when plugged into the grid.

Not necessarily. The current flowing from solar cell to controller is
likely to be nearly zero when not feeding the radio. You won't be
interrupting much current in that case, and would generate little if any
noise.

I'm suspecting
something about the link between the inverter and the radio power supply.

Have you done any common-mode filtering of the leads from the inverter and
the radio? I have an inverter - claimed to be very radio-quiet - that makes
a mess of the FM band. I never bothered to try filtering since I seldom use
the setup. It was powering a laptop computer, but once the battery charged,
I could run for 2 or 3 hours without the inverter.

The radio is an ancient Sony from 1975. Yes, it is time I replaced the
radio...

Why? I don't see that as being part of your problem.