[Mike Rivers]

On Sep 13, 9:34 am, "AndyP" wrote:

Does a preamp with a transformer balanced input do a better job rejecting
RF?

Almost always.

But we haven't established yet that Truth has an RFI problem, or if
RFI is hs only problem. The radio station is definitely suspicious but
the description of the noise as a squeal that's sometimes unbearable
suggests feedback.

All of his gear is good quality stuff so I'm suspecting either cockpit
trouble or something broken. I wonder what he hears when he
substitutes a different mic for the Royer, or better yet, substitutes
a "dummy mic" - an XLR plug with a 150 ohm resistor connected between
pins 2 and 3.