John wrote:
I'm endeavoring to obtain an SWR analyzer to measure the radio
antenna's performance. Short of that, is there any other way for me to
tell if there is too much RFI behind the panel or the DAD just has some
problem that is amplifing an acceptable level of RFI?

With the PTT pressed, wiggle the antenna coax cable adjacent to the
connector on the back of the radio. If the connector is the problem
(which is likely), the vario reading should bounce around as you do this...

Marc