Getting nmea data out of Signal K/OpenCPN

[Techstyle]

1. try hooking the VHF to the GPS directly - this will ensure the issue is not on the Icom end.
2. try hooking the VHF to the 3rd port of the mux - this will solve the GPS getting to the VHF issue (if 1. works)
3. after this, you then can work on getting the NMEA 0183 data out to Autopilot