I think you're out of luck, but you should ask Garmin - they were prompt and
helpful to me when I was trying to get my Garmin to talk with my Furuno
radar.
My MapSource (Version 6.3) says to be sure the device's transfer mode is set
to Garmin.
An option would be to use a handheld set to NMEA with a PC cable for the
radio, and as a backup.
For my radar, I bought Furuno's cable and put a DB9 connector on the end, to
receive the DB9 connector from my Garmin.
I use my GPS 12 in a mount on the instrument panel to feed the radar, since
the PC cable has a 12 volt plug and I don't have to worry about draining the
AA batteries all the time.
I have an eTrex that I use as a backup and I have a PC cable for it, too, so
I can connect it to the radar if necessary.

"Lisa Collins" wrote in message
...
Bob wrote:

I have a new DSC VHF marine radio with a + & - input for a GPS in NMEA
format. I have my Garmin MAP76 outputting in Garmin format on RS232 to
an
older laptop running Mapsource on my boat as a chart plotter. I would
like
to get the required signal to the radio - any ideas or suggestions ?
Thanks, Bob
I do not recall if your Mapsource software requires a data in Garmin
format
or not. If it does not, you can select a NEMA out on your Garmin GPSMAP76
and on your Mapsource software. Then you can do some cable surgery and
make what amounts to a serial Tee connection. The other end of the Tee
would connect to your radio. Generally you can get away with this since
most serial devices don't drag down the 5 volt signal signficantly.

NEMA offers a variety of information on postion, satellite info but does
not
have the provision to handle stored waypoints. The more I think about it
the more I suspect NEMA may not be supported with your Mapsource software.

If we assume that your Mapsource can only accept Garmin data, then things
become more complicated. If you have a second serial port on your laptop,
you can install a low level driver to convert serial data in a Garmin
format to a NEMA format and output it on the second serial port. Several
years ago I saw a freeware window95 program that would do conversion in
real time but I do not know if it even exists anymore.