Help connecting gps/fish finder to VHF radio

[71Windsor]

Hello all. I have a Lowrance Elite-5 HDI And a Cobra Marine VHF MR F55-D The VHF radio came with a dongle with a simple red and black wire coming from it. Book says that red is positive black is negative. Now on the lowrance I have Yellow TX (+) Blue TX (-) Shield (Ground) My question is would I use the yellow and connect it to the red on the VHF then blue to the negative on the VHF? But I also was thinking that the yellow might be high power transmit and blue might be low power transmit then I would use the shield (ground) to the black from the VHF. So would I only the yellow or only the blue from the lowrance and disregard the one I'm not using like if I'm using yellow disregard blue or the other way around. Then connect the shield from the gps to the black on the VHF. Or take the yellow to the red and blue to the black and then ground out the shield (ground) to a common ground source? There's nothing that specifically states what those wires from the lowrance are. Either the yellow and blue are high and low power transmit wires or they are the positive and ground wires I'm looking for. Thanks in advance to any one who can help.

 

[GA_Boater]

Look at this, especially post 3 where the OP called Lowrance. Its for a different model Lowrance and Cobra, but Lowrance NMEA is Lowrance NMEA and Cobra GPS interface is Cobra interface. http://www.gpscity.com/questions?qid=40862 Hope this helps.

 

[jhebert]

NMEA-0183 signals do not have polarity. The first step is to identify the signals. The signals are usually identified in the owner's manual. Interconnection is easy. See

http://continuouswave.com/whaler/ref...eNMEA0183.html

 

[71Windsor]

Thank you for the help. I would have never guessed to tie the TX - and the ground wire together on the same strand. But incase any one searches for this setup the correct wiring for me was. Yellow TX + from Lowrance to Red + Cobra VHF and Blue TX - and the Ground Shield Wire (put these together from the Lowrance) and Connect them to the Black - On the Cobra VHF

That is the winning combination I sent a test distress signal my lowrance received it and send my location over the radio to the receiving operator and verified.

****Warning unless you are given permission ahead of time DO NOT SEND A DISTRESS SIGNAL TO TEST YOUR EQUIPMENT****** you will be in violation of many laws and regulations. I am a part time responder for my local State Police Marine and Coast Guard rescue and made all required arrangements for this test.

 

[NYBo]

Glad you got it figured out. Looks like Mr. Hebert to the rescue again!

****Warning unless you are given permission ahead of time DO NOT SEND A DISTRESS SIGNAL TO TEST YOUR EQUIPMENT****** you will be in violation of many laws and regulations. I am a part time responder for my local State Police Marine and Coast Guard rescue and made all required arrangements for this test.

Thank you for posting that. Unauthorized distress calls risk lives and cost big bucks.

 

[jhebert]

I would have never guessed to tie the TX - and the ground wire together on the same strand.

You should not connect an active TALKER B (sometimes called TX-minus) to ground. If your LISTENER does not have a LISTENER B, let the TALKER B float.

 

[kjsAZ]

You should not connect an active TALKER B (sometimes called TX-minus) to ground. If your LISTENER does not have a LISTENER B, let the TALKER B float.

absolutely correct! The newer marine NMEA018 is a RS422 (differential) and not an RS232 (single ended) any more like it is commonly used in other NMEA0183 equipment (like GPS pucks).
The correct connection for marine NMEA0183 is TX1+ to RX2+, TX1- to RX2-, RX1+ to TX2+, RX1- to TX2- ( 1 = equipment 1 and 2 = equipment 2), ground connection is NOT desired. According to spec you can drive an RS422 with a single ended RS232 but you lose the advantage of the differential driver and the mandatory isolation of the ground (usually an opto-coupler).

To test equipment all you have to do is hook up a dummy load instead of the antenna. Listen with another radio as the dummy load will still emit a tiny bit of signal which you can receive in very close vicinity. Just don't do this a few feet away from the CG stations antenna or in the middle of a harbor/marina