On Thu, 28 Jul 2005 16:49:33 +0200, Mark Veldhuis
wrote:

When I have just the center pin of the PL259 plug connected to the
receiver, much of the buzz disappears. As soon as I connect the other
part of the plug too (the shield of the coax, so to say), it becomes
audible again.

Hi Mark,

Sounds like a ground loop. If you are using the Antenna Interface,
make all connections that give you this interference. Now, disconnect
the power lead to the Antenna Interface. If the noise goes away, you
have a ground loop that is associated with where your power to this
unit comes from, and what you are using as the ground for your
IC-R75.

73's
Richard Clark, KB7QHC