"Johnhh" wrote in message
...
Oh boy, on a scale of one (none) to ten (good), my understanding is
proably
about a 3, so bear with me. To complicate it further, I have lots of
other
Nmea devices to hook up berfore I'm through. Radar, computer, DSC radio,
second or alternate GPS, but we don't need to get into that.

When I hook up the one GPS, both the NMEA in and out are going to be
grounded at or near the GPS. If I understand correctly, you are saying
that
that is ok provided that it is only grounded at one point, correct?

From the GPS to autopilot, this is ok. From another device to the GPS
theoretically it is not ok, but there is not much you can do about it. As
long as you keep signal and ground close together and possibly short runs of
cable, you'll be fine in most cases.

Now, if I run shielded signal wire, where should the shield be grounded,
or
does it matter?

The common consensus is to ground the shield at the talker side, at the side
where the data is generated. Do not use the shield as signal- or ground
return but you can't anyway if you connect the shield only on one side.

Meindert