VHF Wire Question

[hijole]

I just bought an ICOM M422 VHF.
Therre are two wires to connect the radio to recieve GPS signals. Each wire has the main wire in the middle with a wire shield around the core like a cable TV wire. I guess it's a ground but not sure.
Does anyone know if this wire has to be connected to a ground?
I connected everything else and couldn't get a GPS reading.

[Wizard]

That shield is a ground, I would think. All NMEA interfaces are one wire data, and one wire to common. But I would think a radio only has a GPS in, no need for some signal out, so maybe those two wires are data and common, and are just shielded, which you would want to ground to reduce any cross-signal. What does the book say?

[NoSlack]

http://www.icomamerica.com/support/manuals/m422_manual.pdf

Section 9 of the online manual has the wiring. (page 35)

Yellow: External speaker
Blue: Public address
Red: NEMA in
White: NEMA out
No mention of the shield.

On my electronics the negative(-) is the common wire for all the above options.

Mike

[hijole]

Thanks Glenn and Mike. The instructions call for both wires in and out to be connected. One is for signals from a caller to be displayed and mine to be sent out for someone to recieve. I'll try connecting the shield to a ground. It makes sense. I didn't connect it because the instructions on page 35 do not say anything about the shield only the center wire.

[hijole]

I found my problem. I had the wires connected the right way all of the time. I was sent additional info on connecting the ground wire from ICOM.
My solution was to upgrade the GPS. I can’t remember when I bought it but I found a software upgrade announcement on the Lowrance web site. This feature was not available on radios when I made the purchase.
I downloaded the upgrade on a XD Memory chip and transferred it to the GPS. Immediately the radio read the GPS settings. There are other features that I also noticed to work better on my GPS after loading the upgrade.