Splitter for GPS Antenna ?

[Rex Delay]

I use two older Garmins, one dedicated to the DSC radio, the other plugged into my laptop for chart program. I have one external antenna mounted on the stern rail. Is there a splitter available to plug the one antenna into the two GPS?

[hellosailor]

Typically not because splitting creates electrical problems. And no splitter would be cheaper than simply buying a new USB GPS for $50 and plugging it into your laptop. The new 3rd or 4th generation GPSes are incerdibly more sensitive than 80's or 90's models, anything with a SirfStarIII or later chipset should work even under a cored fiberglass deck. And it probably will be WAAS-enabled, more accurate than the old stuff as well.

[donradcliffe]

If both units use a similar external antenna with a coax cable you MAY be able to run both off one antenna. The older garmins use a powered mushroom antenna, where the unit put 5 volts DC across the coax cable to run the amplifier in the antenna. As long as both units have this system (if you measure 5.0 vdc across the coax when the unit is on), you can use a T connector to drive both units--with the amplifier there is plenty of signal to share between them.

[fairbank56]

Assuming you are talking about coax fed antenna's and not antenna's with integral GPS receiver's with multi-conductor cable feed, yes, they make splitters. I have used them in large ship applications but never for recreational boaters. They are expensive. I would not just try to use a tee adapter. These antenna's are dc powered thru the coax and you would not want to directly parallel the outputs of both GPS units. This would also screw up the 50 ohm impedance that should be maintained between antenna and receiver. The splitters will block dc from one port and maintain the 50 ohm impedance match.

Eric

[donradcliffe]

Every EE I talked to told me they wouldn't recommend it, but it does work fine.
I measured the DC voltage across one coax at 4.98v and the other was 4.97v, so I crossed my fingers and tried the T. There may be some impedance mismatch, but both GPS's show strong satellite signals. Saves running cable and mounting two antennas.

[Rex Delay]

"And no splitter would be cheaper than simply buying a new USB GPS for $50 and plugging it into your laptop."

That sounds like an ellegant solution. Where do you find these things? Anyone I talked to yesterday had never heard of one.

[Rex Delay]

I did not know these USB devices existed. Just ordered one and now have freed up the handheld for other uses and cleaned up the mess of wires at the chart table. Thank you all.

[Rex Delay]

The new Garmin USB GPS will not communicate with the Garmin Blue Chart program! Back to square one - looking for a splitter again.

[Rex Delay]

My 76S and GPS II interface flawlwssly with the Blue Chart program. The idea was to reduce clutter on the chart table and I thought a new generation USB GPS would clean things up. The laptop would recognize the GPS but the Blue Chart program would not. Was easier and more efficient to return to my previous ways than to upgrade the chart program.