[macsailor]

I also have my old Map76, it has a cable with an small connector on the end, DB9 (?). What you are saying is this cable should plug into the the Map76Cx and provide the signal required for the VHF.
It is too bad someone does not produce a GPS puck for this application, it could sit near the VHF and be a dedicated GPS just for this purpose.

thanks again, Bob