Kenwood IF-232C USB Replacement Interface

For those of you with ye olde Kenwoods, this little rig control interface may be of some interest to you. It does what the Kenwood IF-232C does but only cost me about $25 and a little time for soldering.  I haven’t tested every aspect of it yet, but I know the VFO changes in both N1MM and Commander from the DXLab Suite.


A couple notes from my experience building it:

Because the site in the tutorial was out of stock at the time, I purchased my board from here:

Also, my board had a solder jumper with two connectors, so I just moved the solder bridge from the 3.3V pin to the 5V pin removing the need for the extra wire jumper in his design.  My board had different connections on the sides so I just connected wires to the connections indicated by the pinouts of the DIN-6 (RTS, CTS, RXD, TXD, GND).  These are clearly indicated on the underside of the board (my board at least).  Yours may vary here as well, so look before you leap.

In addition, the mappings to the DIN-6 connector are as you’re looking into the radio, not as you’re looking into the connector. I discovered this the hard way and had to do some resoldering.

One last note: FTDI released a successor for MPROG called FT_Prog which works perfectly fine for programming the chip for the inversions needed. Drivers are available on their site, but Windows 7 SP1 x64 pulled them down from Windows Update without a problem.

There is also a utility on the FTDI site to remap COM ports if the chip ends up with a COM number greater than 8 (the max N1MM supports).

73 and Happy New Year de K1MAZ


6 responses to “Kenwood IF-232C USB Replacement Interface”

  1. Robin Midgett Avatar
    Robin Midgett

    Thanks for the updated info. On my IF-232, there is a red Tx & a green Rx LED on the corners of the board opposite the USB connector. These stay lit all the time, and I can’t seem to connect to the radio via Ham Radio Deluxe. I don’t think the LEDs should be on all the time. Can you offer any suggestions?

    1. Hello,

      Are you sure you’re using the right settings in HRD? It sounds like the data isn’t flowing. In N1MM I used to use 4800, N, 8, 2, Handshake, Handshake.

      Nick K1MAZ

      1. Robin Midgett Avatar
        Robin Midgett

        I believe I am using the correct settings in HRD. I’m more inclined to think I don’t have the correct drivers for the USB-Serial breakout board installed, or that the FTDI chip is a fake. There were some issues with fake FTDI chips from China, based on my reading in different groups. I’ve also been burned with fake RF power transistors from China recently, so this issue seems to be growing.
        Tonight I plan to attempt a loopback test with the FT232 RL. Once I have that working, I think HRD will be happy to play along.

        1. Robin Midgett Avatar
          Robin Midgett

          Update: Thinking the original USB-RS-232 breakout board was defective, I ordered another one. I programmed it using the same software as the first. I was disappointed to see the Tx & Rx LEDs light up & stay on continuously, as before. Reading further, and having not tried a loop back test, I found this document very helpful:
          The link to the terminal program in that document is dead, but I found the download at:
          Once installed and the loop back jumper installed on the break out board, I found the loop back test to be successful. I tried the loop back test on both USB-RS232 break out boards & both worked as hoped.
          I then reconnected the original USB-RS232 board to the radio, checking the connections on both ends. I launched HRD & set the serial port parameters as necessary…viola, it works!
          I wish I could say what was wrong in the first place, but I can’t. I wish I knew why the Tx & Rx LEDs stay on continuously. Maybe in the future.
          Thank you for the helpful article.

          1. Robin Midgett Avatar
            Robin Midgett

            LED issue resolved! Reading the data sheet, I came to realize the I/O control options C0-C4 must be selected properly within MProg (assuming the same for FT-Prog) in order for the LEDs to follow the data on the Tx & Rx lines. The settings I found to work are: C0 set for TxLED#, C1 set for RxLED#, C2 set for TxDEN, C3 set for PwrOn#, & C4 set to Sleep#. C0 & C1 seem to the the critical values. The others I chose so as not to conflict with C0 & C1.

  2. Clint maile Avatar
    Clint maile

    Great article.

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