When the SW interference got worse today, I walked around the room (to
start out) with my 396 and noted that the hum was so loud next to my
computer that the signal light lit up. I turned off the power supply and
the noise went away. I'm thinking "great, I need to buy ANOTHER surge
protector". But then I played a hunch and started unplugging stuff one
by one to see if it's really the surge strip and when I unplugged my
computer's printer the noise went away. Plug it back in, and the noise
returns. So instead of spending $20 on a surge protector, I'm looking at
$120+ for a new printer. But that's ok since it was acting up in other
ways, for example the paper feed quit working so it wouldn't
automatically feed paper through, I had to feed it each sheet by hand.
It's not always a power line problem, guys. I think the other guy who
was having a hum on the tropical bands should try what I did.