: How could my nav radios (or my handheld) be contributing
: to this problem when they are *powered off*?

Did you ever build a "crystal" radio when you were a kid? It's an AM
radio that receives stations and powers an earphone using only the
energy received through the antenna. If there is enough RF energy in
the air (say at an antenna farm), there is enough power being received
by the antenna to make the powered off radio into an analog of the
"crystal" radio. The powered off radio uses the received RF energy to
become an oscillator (transmitter).

: Could someone explain this to me please? I'm not an electronics
: wizard (obviously) but I do know a little bit and this just seems
: very "twilight zone".

Does that help?
--
Aaron Coolidge (N9376J)