This post is a final version of the Help Wanted post of the same title. I will outline how to build and connect the M710 Remote Cable.

The Icom M710 Marine SSB and HAM Radio has a DB9 port on the backside of the main body (for those with the RT model which has a remote face plate). This is technically called a NMEA port. Via a custom cable you can connect it to a standard PC Serial port and control the radio with the following software programs:

I first bought a male to female DB9 Serial Cable. I then cut it, filleted out the wires and with my multimeter in continuity mode, I identified which pin\hole went to which wire. You can not rely on the colors of the wires, there is no standard for that. I verified both sides of the connections just to be safe. This picture shows the ports\pins and the proper numbering.

NMEA Remote Control Cable for Icom M710

The ICOM end is based on this drawing from the ICOM M710RT Manual. This is the DB9 port on the back of the main unit by the Clone jack and accessory jacks. It is not the one on the front of the main unit by the jacks for the face plates.

Icom M710 Remote Pinout

Once I filleted out the wires and labeled them I then connected them as per the directions I have found on various web sites. Here’s how that is written:

M710, M700pro:

A cable to a standard PC serial port can be made up as follows:

The 9-pin NMEA "Remote" connector (labeled "DSC" on some models) can be used for remote control of the transceiver mode and frequency with any controller type, by using an additional computer serial COM port. NMEA signal levels are a differential version of RS-232 voltage levels, approximately +8 and -8 volts. With appropriate wiring the "+" NMEA connections can be connected directly to a RS-232 serial port. (Note that the "-" input must be grounded as a reference, but do not ground the "-" output).

    # ----------------- ----------------------
    # ICOM 710 Remote   Computer Serial port
    # (9-pin male)      (9-pin female)
    # NMI+ 5            3 TxD
    # NMO+ 7            2 RxD
    # NMI- 6            5 GND
    # GND 9             5 GND
    # Shell / Shield    Shell / Shield
    # ----------------- ----------------------

Icom m710 remote

Pc serial port

If you look at these two pictures and match the colored alligator clips you will see I’ve connected them as follows:

    # +-------------------------+-------------------------+-------------------------+
    # | REMOTE                  | Alligator Clip          | PC                      |
    # +-------------------------+-------------------------+-------------------------+
    # | 7                       | Yellow                  | 2                       |
    # +-------------------------+-------------------------+-------------------------+
    # | 5                       | Red                     | 3                       |
    # +-------------------------+-------------------------+-------------------------+
    # | 6,9                     | Green                   | 5                       |
    # +-------------------------+-------------------------+-------------------------+
    # | Shield                  | Black                   | Shield                  |
    # +-------------------------+-------------------------+-------------------------+
    # | 1,2,3,4,8               | Cut these off flush and | 1,4,6,7,8,9             |
    # |                         | tape them off so they   |                         |
    # |                         | will not touch anything |                         |
    # +-------------------------+-------------------------+-------------------------+

With this setup connected to the REMOTE port on the radio you should be able to control the FREQ, Mode, NB, SQL settings with one of the software packages. The DIMMER and SPEAKER buttons did not work for me, but I didn’t think they were that important.

I’ll have more on the SW packages in the future. Once you know the cable works, you can solder and shrink wrap the connections.

NOTE: I have found no functional improvement using the REMOTE port as opposed to the 1/8” CLONE port. All the same functionality worked through each port for me. The clone cable can be readily had on Ebay. Search for OPC-552. The cable is a DB9 serial port on one end and an 1/8” jack on the other.