William Mutch wrote:
snip What I'm hearing is some strange signal which seems to have a
surpressed carrier on 500.0 and sidebands both above and below at about
6 khz intervals...ie +/-6, 12, 18, getting radidly weaker as they get
further from 500 khz. They are modulated A-2, MCW, with what seems to
be code with three characters...a dit, a short dah, and a long dah send
in the format {long dah, two dits, variable number of short dahs (n= 3
to ~20), long dah, pause} with timing like a busy signal on a landline
phone.

Could be a parasitic from an aero beacon. Try tuning around the beacon
frequencies (around 300 to 400 KHz if I remember right), and check
for a beacon tone-modulated at the same time as the spur on 500 KHz.

73,
Ed Knobloch