Yaesu FT-2600M VHF mobile with DB9 on rear panel

Let’s start with the basics. I have the Yaesu FT-2600M VHF radio with a DB9 connector on the rear panel, Digirig RS232, RS232 Cable. I’m not sure this is the correct setup for this radio but I took a gamble and worst case I’m out on this specific cable as I can repurpose the digirig for the KX3 with a different cable or worse move solder around to change it for another setup.

Once I received the RS232 cable I checked the pinout with a continuity test. The plug end is a TRRS (3 black bands). The continuity test on the jack shows:

  • Tip goes to pin 3 on the DB9
  • 1st ring from tip end goes to pin 2 on the DB9 side
  • 2nd ring No Connection
  • Shield goes to pin 5 on DB9 side
  • Pins 7 & 8 shorted together
    I decided to look at the Yaesu FT-2600M Manual to see what the pinouts were for the DB9. PDF is available at Yaesu website for the radio.

FT-2600M DB9 Pinout

Pin 1-Squelch Signal Output
Pin 2-Packet RX Data Output 9600 BPS
Pin 3-Packet TX Data Input 9600 BPS
Pin 4-Packet Data Output 1200 BPS
Pin 5-Ground
Pin 6-Not used
Pin 7-External PTT signal Input
Pin 8-DC Output
Pin 9-Packet Data input 1200 BPS

I’m almost certain that RS232 cable isn’t the answer. Now next question is what do I need to make this work as my intention with this used radio I purchased with the DB9 was to put it to use in some some sort of digital/packet radio setup. I’m leaning towards dabbling with APRS and a raspberry pi zero 2W for that.

Do I need the audio and serial from the radio back to the digirig? If so can anyone walk me through this. Am I going back to the store or making cables for this setup and if so I need a schematic from someone clever enough to lay it out for me to follow. TIA for the help provided and information.

It sounds like while ringing the pins on the serial cable you mirrored the pin numbering. The connections are to pins 2, 3 and 5. There is also connection between pins 7 & 8 for hardware flow control loopback.

Anyway, from the FT-2600M pinout you supplied it doesn’t appear to be a serial connection. It’s a strange choice by the manufacturers to use the types of connectors that have strongly associated functions (DB9 = serial) for alternative uses (transceiver audio) while industry standards exist (MiniDin6). Next thing we’ll see HDMI ports used for power. [end of the rant from guy who used 3.5mm TRRS sockets for two different functions on the same device]

You’ll need a different cable which will plug into Digirig’s audio socket on the other end. Similar situation is with Alinco DR-135T, and now that we looked at it, the pinout appears to match:

So you can just go with this store cable:

Please report your results and I’ll update the compatibility tags accordingly.

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For your reference here’s a closeup of the female DB9 connector with the pin numbers shown in molding. Highlighted pin #5 should ring to sleeve (GND) on 3.5mm TRRS side.

For reference with FT-2600M DB-9 pinout from owners manual

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I cleaned up my errors but leaving the correct answers for reference.

Reference to avoid simple mistake.

In hind sight look at your radio again before ordering instead of remembering it has a DB9. You need to compare M/F connections. Simple stuff but that always causes mistakes. Two female ends is what I had.