Connecting VFH to GPS

[TB081]

First off I would like to say this is a great site you guys have. Lots of good info here.
A friend of mine ask me to connect his VHF radio (Lowrance Icom IC M304) to his GPS (Lowrance LMS 525c DF). I've search the threads and still need some help.
On the VFH I have 2 wires that goes to the GPS;
Green (NMEA IN -)
Yellow (NMEA IN +)

On the GPS I have 4 wires;
BLUE (not used according to specs)
SHIELD
YELLOW (out)
ORANGE (IN)

Now if I'm right, do I connect VHF YELLOW (NMEA IN +) to GPS YELLOW (OUT)?
and VHF GREEN (NMEA IN -) to GPS ORANGE (IN)? Also, where I'm I suppose to connect my shield?

I greatly appreciate your help!

 

[bruceb58]

Re: Connecting VFH to GPS

The shields all go to ground.

 

[jhebert]

Re: Connecting VFH to GPS

Your proposed connection is not correct. Two inputs would not be connected to each other.

To connect serial data devices you connect an OUTPUT to an INPUT.

Connect the OUTPUT from GPS receiver to the INPUT of the radio transmitter.

According to your information the OUTPUT from the GPS is the YELLOW lead, and it apparently is unbalanced and works against ground or the SHIELD lead.

According to your information the non-inverting INPUT (+) to the radio is on the YELLOW lead and the inverting (-) INPUT on the GREEN.

With an unbalanced output, connect the output to the non-inverting (+) input. Connect the inverting (-) input to the power negative or ground.

GPS----------------------> RADIO
OUTPUT-------yellow---> >---yellow----NON-INVERTING INPUT (+)
GROUND------shield----> >---green-----INVERTING INPUT (-)

 

[jhebert]

Re: Connecting VFH to GPS

You are probably asking about a VHF Marine Band Radio. The acronym VHF is for Very High Frequency. There is no acronym "VFH" that is associated with marine radios.

The VHF spectrum is from 30-MHz to 300-MHz.

 

[TB081]

Re: Connecting VFH to GPS

thanks for the replies. "VHF" I misspelled it.

I'll connect the wires jhebert suggested and post the results later on. I guess then I don't need the VHF ORANGE (IN) after all. In what case would you use that one? One other question, is it mandatory to connect a NMEA 2000 network in order for your GPS and VHF to talk to each other?

 

[bruceb58]

Re: Connecting VFH to GPS

If you want to see where people are that are in distress.

 

[jhebert]

Re: Connecting VFH to GPS

I guess then I don't need the VHF ORANGE (IN) after all.

Did the ORANGE wire move? Before it was on the GPS receiver.

 

[TB081]

Re: Connecting VFH to GPS

Sorry jhebert,
The GPS ORANGE wire (IN). I suppose I'll just have to cap it since there is no connection for it on the VHF receiver.

 

[jhebert]

Re: Serial Data Input to Electronic Chart Display

Re: Serial Data Input to Electronic Chart Display

The NMEA-0183 serial data input on the Lowrance LMS 525c DF is not associated in any way with its Global Positioning System receiver. The GPS receiver is actually a separate unit, and it communicates with the LMS 525c DF via NMEA-2000 networking.

The NMEA-0183 serial data input to the LMS 525c DF appears to be provided as input to the electronic chart display of the device. However, how the electronic chart display will react to any NMEA-0183 sentences supplied on the input is not clearly explained in the manual or in the operating system. There is a general assumption that, if the electronic chart plotter receives a NMEA-0183 sentence on that serial data input, it would do something useful with it, for example, present some information on the electronic chart display, but this is not documented anywhere that I could find.

If you wish, you could connect the NMEA-0183 serial data input on the LMS 525c DF to the corresponding NMEA-0183 serial data output from a Class-D DSC VHF Marine Band Radio. However, the ICOM M304 is not such a radio, and it lacks any NMEA-0183 serial data output. In this particular case, there is no useful purpose for the NMEA-0183 serial data input to the LMS 525c DF unit, and you probably should simply insulate the wire and leave it unconnected.

For a comprehensive review of the NMEA data communication capabilities of the Lowrance LMS 525c DF, please refer to

http://continuouswave.com/whaler/reference/L500.html

 

[TB081]

Re: Connecting VFH to GPS

jhebert you're awsome! That was a great reply.

thanks man.

 

[TB081]

Re: Connecting VFH to GPS

Ok I connected the 2 wires together late last night. I haven't had the time to do a full test but by first impression it worked. Now, one thing I realised is that the is static noise out of my radio only when my GPS is ON. Here is how I connected the power cable for both the GPS & VHF radio;
VHF radio (red wire +) ------> to inline switch ----> to battery positive lead
VHF radio (black wire -) ------> to neg lead on battery

GPS (+) -----> to same inline switch (its a double load) -----> to 3amp fuse --->to battery positive lead.
GPS (-) ----> to neg lead on battery.

I think there might be interference somewhere around my switch since both positives from the GPS & VHF goes to the same switch. What you guys think?

 

[TB081]

Re: Connecting VFH to GPS

I found the problem. Turns out like I suspected, there was interference on that switch. I simply removed my VHF + wire and directly plugged it to my battery. I left the GPS display on the switch. Resulted much better and barely any interference. I also tested the GPS & VHF and it worked perfectly as they're talking to each other.
Thanks to the people who replied and help me on that little project, much appreciated.