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Connection and Setup of the Yaesu FTM-350R and Garmin Nuvi 350 using the Argent Data Systems GTRANS cable


Connecting your Yaesu FTM-350R to the Garmin Nuvi 350 with the Argent GTRANS cable unleashes the potential of your radio and your Nuvi 350 allowing you to dynamically interact with a visual APRS network.

Nuvi 350 Map View with APRS Objects

Here's what the GTRANS Cable can do for you:

  • Act as the GPS for your FTM-350R so you don't need to buy the $80 GPS puck from Yaesu in order to use the GPS functions of the radio
  • Translate the NMEA APRS Packets from your FTM-350R and display them on the map and in the favorites of your Nuvi 350
  • Automatically update waypoints as new APRS packets are received
  • Allow you to navigate to any received APRS station (Note: this will NOT automatically update as you are driving towards a target)
  • Give you a really useful map of all the APRS stations received

What the GTRANS cable will NOT do for you:

  • It will NOT enter DISPATCH mode on the Nuvi
  • It will NOT send or receive messages on the Nuvi (you'll have to do that through the radio still or get a Tracker 2 or 3)

Note: The Garmin Nuvi 350 is no longer in active production but many can be found on eBay or Craigslist for ~$20-$80 (as of March 2012).

Another note: The GTRANS cable is a translating cable that translates between the proprietary Garmin FMI protocol from the Nuvi 350 and the standard NMEA format that is used by many devices including the FTM-350R.

One last note: This document also applies to the FTM-350AR which is identical physically to the FTM-350R just with the updated firmware. Many will also reference the radio simply as the FTM-350.

Equipment Needed

Yaesu FTM-350R Setup

FTM-350R Menu Settings

The FTM-350R COM port needs to be setup correctly for communication through the GTRANS cable as such:

  • Enter the APRS Menu: (Press: "SET", then select "APRS/PKT")
    • FTM-350 - Setting APRS PKT Menu.JPG
  • Scroll to menu item: "E16 COM PORT SETTING"
    • FTM-350 - Setting E16 COM Port Setting 1.JPG
  • Set the following parameters:
    • 1 SPEED: 4800 bps
    • 2 OUTPUT: PACKET (sets the radio to output NMEA waypoint packets that include the comments and APRS icon info. Note: WAYPOINT can also be used but will only display the callsign and location and not display APRS icons)
    • 3 INPUT: GPS IN (sets the radio to get its GPA data from the Nuvi's GPS receiver)
    • 4 WP FORMAT: NMEA9 (allows for full-length, 9-character APRS callsigns to be displayed)
    • 5 WP FILTER: ALL (or whatever filter you want set)
    • FTM-350 - Setting E16 COM Port Setting 2.JPG
    • FTM-350 - Setting E16 COM Port Setting 3.JPG

NOTE: If your radio has not yet been setup for regular APRS use, please refer to the APRS Operating Manual page 4-12 to ensure all your other settings.


The following connections are required for correct operation:

  • The Nuvi 350 must be in its charging cradle and receive power from the cradle in order for the GTRANS cable to receive power. Connect the GTRANS USB mini-B right-entry connector to the side of the Nuvi as shown:
    • Nuvi 350 - Device Labled.JPG
  • Connect the 8-pin mini-DIN connector to the DATA port on the back of the radio
    • FTM-350 - DATA Port.JPG
  • The completed setup should be as shown in this diagram:

Power Up

Once everything is hooked up and correctly configured you should see the following:

  • Power on the Nüvi 350: The battery symbol in the upper right screen corner shows a lightning bolt
    • Nuvi 350 - Home Screen.JPG
  • Incoming GPS Data on the FTM-350R: Once the Nuvi has a GPS lock, it should start sending NMEA position data to the FTM-350R. This is indicated by the "GPS" Icon which should be visible in the upper right corner of the FTM-350R display. It's worth noting that when the FTM-350R receives it GPS data from the Nuvi, it always thinks that there are 8 satellites visible, regardless of how many the Nuvi actually has visible.
    • FTM-350 - Setting GPS Screen.JPG
  • Incoming APRS Packet Waypoints should appear as they get received the Nuvi's "Favorites" menu
    • Nuvi 350 - Favorites Screen.JPG

Waypoint and POI Management on the Nuvi 350

APRS waypoints and POIs (Points of Interest) are handled a bit funny on the Nuvi when used with APRS. Please visit the following two wiki pages to further explore this area:

Debugging and connection notes

GTRANS Cable Pinout

GTRANS Cable PCB Detail

Your GTRANS cable should come assembled with the following pin connections:

  • GND to GND
  • NMEA IN to TXD (the serial OUTPUT to the radio)
  • NMEA OUT to RXD (the serial INPUT from the radio)

The connection to the GTRANS board should be as follow (colors may vary):

GTRANS side of cable
FTM-350R 8-pin mini-DIN detail

It's worth noting that Yaesu's originally published APRS Operating Manual contained an INCORRECT pinout. The new one on their website should be correct (verified 3/11/2012 on page 83 of the APRS Operating Manual). Here's the correct one:

FTM-350 - COM Port Pinout.JPG

RS-232 Voltage Levels

If you run into serial communication issues here are some reference values for correct levels (these can be verified with an oscilloscope):

    • Peak-to-peak voltage: ~11.5V
    • Packet length: ~400ms
    • Packet interval: ~1 sec
    • Packet rate: 4800 baud (this means ~4.8KHz frequency of the bits)
  • FTM-350R TXD Port
    • Peak-to-peak voltage: ~5.4V
    • Packet length: varies
    • Packet interval: varies based on receive APRS data
    • Packet rate: 4800 baud

Sample Packets

If you look at these outputs directly with a serial port on your computer, you should see raw text on the terminal in a similar form to these sample packets:

  • GTRANS NMEA OUT Pin Sample Packets
    • $GPGGA,061321,3518.5232,N,12039.6007,W,1,08,1.0,152.8,M,-31.2,M,,*7C
    • $GPRMC,061321,A,3518.5232,N,12039.6007,W,0.8,150.0,060312,,*03
    • $GPGLL,3518.5232,N,12039.6007,W,061321,A*3E
  • FTM-350R TXD Pin Sample Packet
    • $GPWPL,3515.85,N,12042.68,W,KD6DSI*3A


Page created by: Marcel Stieber AI6MS (March 2012)

Many thanks to those who have also contributed to this page including:

  • Anthony Mascola KJ6OKV (created the original Kenwood TH-D72A page from which this page was modeled)
  • Jessica Sherbon KJ6DNR
  • Justin Kenny KJ6KST


Adapted from GTRANS Kenwood TH-D72A

Pinouts from Yaesu