"krj" wrote in message
. ..
Larry,
Do you have ferite beads at both ends of all your NMEA cables? If so, do
they help?

Ferrite beads don't do much on HF, but all the more on VHF. But like I said
in me other replay, it's more important to terminate the wire correctly. If
you have a shield, do not use it as a signal return as with coaxial cable.
Only connect it on one side so no current can flow through the shield,
otherwise it will radiate being a perfect antenna.

Meindert