Thanks for the information, but I still am fuzzy on details about the various ground wires.
The Navman manual you pointed me to shows the same diagram in Navman manuals I found, clarifying that the shield is shrink-wrapped so that it can be connected to something, but they are not clear on what to do with it. One Navman manual I found says either black wire can be connected to ground (presumably boat's DC-negative), and that they are connected inside the cable. But I want to connect the NMEA GPS-to-VHF wires too. So, I have two problems: picking the right GPS wire to connect the GPS to DC-negative, and picking the right GPS wire to connect to the VHF's ACC cable Brown wire.
The Northstar manual does not specify whether the shiney black wire is "NMEA ground", or just a common ground. It does not mention that there are two black wires in the power-data cable.
The Uniden customer support knowledge base gives this:
"Here is the basic wiring method between the Solara DSC radio and a GPS: (+) Radio GPS data IN wire (GREEN) TO (+) GPS/NMEA data OUT wire; (-) Radio GPS ground wire (BROWN) TO (-) GPS ground wire". Is that any DC-negative ground wire, or a special NMEA ground wire?
The VHF's manual tells me to connect its Green to "GPS data in" (that would be Northstar's White NMEA out wire in the power/data cable), and its Brown wire to "GPS GND", but I can't figure out which GPS wire to use. Can I just run it to boat's DC negative ground, or is there something special about the NMEA module's ground wire signal?
To add to the confusion, the radio's ACC cable also has a thick Black wire labelled "DC GND", which obviously can connect to boat's DC-negative, but it is not clear whether it is necessary to hook that one up too. http://www.uniden.com/pdf/solara%20dsc-BKom.pdf
What if I connect this way?
1. The GPS shiny Black wire to boat's DC-negative.
2. The GPS White wire to VHF Green "GPS data in".
3. The VHF Brown "GPS GND" to boat's DC-negative (or does it have to be a ground from the NMEA module in the chartplotter??).
4. Leave the shield "wire" (flat black) unconnected?
5. Undecided about the black wire in the ACC cable of the VHF (the main red and black power cord wires are already connected and the radio works).
6. The VHF ACC cable thick black wire to boat's DC-negative.