Which is the approximate maximum speed of the Chevrolet c80 truck of the year 1962 with the most powerful engine

SOURCE: Whenin use, my c80 emits a series of 3 loud beeps

You have triggered MOB (man over board) press and hold the MOB button in for 30 seconds.

SOURCE: takes sometimes upto an hour to get fix 120/ c80

look after your software version it shoud be 4.29 after this make a reset (you will lost all the data like waypoints routs and other)

SOURCE: GPS antenna

If your old antena is a Seatalk or NMEA antena you can use it for your C80
If you GPS antenna is older than five year change it.

SOURCE: scanner self test result...is display comms/fail /raymarine c80 18" dome

Chances are that your scanner cable may be bad. Check inside the dome and make sure that the little wires going into the black connector from the radar cable are seated correctly and all the way in. This can cause tons of problems. Also check to make sure that your pins in the back of you unit are not corroded or broken off.

SOURCE: what is the connection path from Garmin 72 to raymarine c80, using NMEA 1083

I'm taking this as you want to send the gps information to your C80 not receive from the C80? If this is the case the brown wire on the garmin is the nmea data out +. The Black wire is considered nmea out neg (-) of the garmin. So hook the garmin brown to the white on the raymarine. Hook the black from the garmin to the green on the raymarine. That means you are outputting lat/long info to the raymarine from the garmin.