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I had a Raystar 120 WAAS (Seatalk) antenna die on me a couple of weeks back. With the help of a Raymarine tech, we've diagnosed the problem to the antenna, and I'll be returning it for warranty repair/replacement today.
However, I've decided I should have a backup antenna and I'm looking for recommendations.
I already have two Raystar displays--both with chart capability, so if one display should ever go down, I can move the CMap-NT chip to the other display. I have redundancy of displays, but now believe I need redundancy of GPS antennas.
The antenna should output on NMEA, so if the Raymarine Seatalk LAN should ever be the problem, hopefully NMEA input would still be able to receive the fix data.
I found a "NAVMAN 1220A" through an internet search that outputs on NMEA. A search for Furuno, Si-Tex, JRC, etc. didn't reveal whether any of their antennas output on NMEA. Some only indicated they had a BNC or SMB connector. A search on Raymarine didn't reveal a NMEA based sensor--only the Seatalk based sensor I already have.
I back mine up with a hand held GPS tied into the NEMA port on com1, If the head dies I turn on com1
and receive position data from the hand held unit, this backs up all GPS function. The handheld is connected to a DGPS receiver as well.
Was looking at a Garmin GPSMap 76 today. Appears that it has a NMEA 0183 output. One page in the manual shows an example wiring diagram of tying it into an autopilot with NMEA.
What handheld GPS do you have? Was it fairly easy to wire it into the NMEA input of the other devices?
Anyone else actually wired a Garmin GPSMap 76 into the NMEA input of another device?
quote:Originally posted by skopje:
... Was it fairly easy to wire it into the NMEA input of the other devices?
Anyone else actually wired a Garmin GPSMap 76 into the NMEA input of another device?
For the purpose only 2 wires, NMEA out from the GPS to NMEA in on the other device but how and where these connect too vary a little but fairly striaght forward.
NMEA protocol (ncluding the 76) is basically standard and for your purpose will only require 2 wires.
Every GPS made basically provides NMEA but just keep in mind that some units have an external antenna that is just a recieving antenna while other units are actually entirely encased in what just looks like any other antenna. The 120 is basically a "GPS in an antenna" where as others like the 76 have an internal antenna (being a handheld) but with the capability to include an additional external antenna (dumb antenna).
So, I also need to make sure I'm getting a smart antenna that outputs NMEA, not a dumb antenna that interfaces to a GPS that processes the signal into NMEA. Got it. Maybe that is why the technical data on the Furuno, Si-Tex, Garman, and other separate antennas gave a connector type, but not the protocol type--they are dumb antennas.
Looks like a handheld with NMEA output is the way to go.
Sorry for the late reply, I received a free Global map100 when I bought my Lowrance, it was very straight forward hooking up the NEMA output to the input, you should have diagrams in your manual. You can have more than one device receiveing data on any NEMA output.
Raymarine replaced the Raystar 120 GPS antenna. Took it to the boat yesterday evening and installed it. Works great. Raymarine gets my stamp of approval for customer service.
Pressure is off to find a back-up antenna. Have a friend with an older Garmin handheld with a NMEA connector. Will see if the two of use can rig his handheld to provide signal to my two Raymarine displays. Once I prove that it works, I'll be on the hunt for my own back-up.
Low-cost backup GPS antenna 
