Do it yourself Yaesu FT-450D Digital interface

Added a Yaesu FT-450D to the station and wanted to get it up on digital modes. So leveraging what I had learned in my earlier posting on USB Sound cards. I gathered up parts to build a cable to connect a USB sound card to the 6 pin mini din socket on the rear of the radio.

The wiring is very simple with only three wires, audio in, audio out and a ground needed. I used a couple of 3.5mm stereo plugs I had bought on eBay and wallah a dedicated digital interface for less than $30 and $20 of that was the USB Sound card dongle.

And as a I have a serial cable for normal CAT control I did not need to mess with the PTT line as I will use CAT commands to key the transmitter.


FT-450 Data plug to 3.5 schematic

FT-450 Data plug to 3.5 schematic

Picture of the finished cable next to the sound card dongle.

The Finished cable

73 Until next time, Jay


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15 Responses

  1. Jim Peisker says:

    Hi Jay, have you tried this setup with Win10? Wondering if there are driver or behavior issues. Jim

    • admin says:


      The devices which I have an have reviewed here on the site work fine under windows 10. When selecting an external sound card from your source of choice (ebay, Amazon, etc) just check if Windows 10 is not supported.

      73, Jay

  2. Jim Peisker says:

    Jay, I’d like to build one of these DIY FT-450 digital interface cables. Not sure which pins of the DIN connector go where, especially when you consider 3P stereo plugs at the sound card end. A wiring diagram, even a crude sketch, would be appreciated. You can post or email to me.

  3. Tom says:

    Hello i am planning to build one i have 2 questions
    1. do you have to use a usb sound card or can you use a internal one
    2. how would i go about doing the pot could you give me an example and how are you doing it over the cat control.

    • admin says:


      The internal sound card can be used, be careful to disable all operating system sounds. In Windows this is rather straightforward setting the sound profile to none. In Ham radio deluxe, WSJT-X, Fldigi and others PTT via CAT is an option best to refer to the documentation specific to package you are using.

      73, Jay

  4. Tom says:

    Hello once again what do i do with the ring on data on if i want to use stero.

  5. Tom says:

    On the data in line do you connect the ring or not and if you do connect the ring what wire do you connect it to?

  6. Arnold Diaz says:

    Does this simple cable take the place of a Signalink USB? I’m trying to install Fldigi on a Raspberry Pi but don’t know how to interface if with my 450D.

    • admin says:

      The cable in conjunction with a USB sound card provides the audio interface portion of what a signalink does. I use a 450D for portable operation running Fldigi and other apps using this setup. You will also need a USB to serial cable for the radio’s CAT port. Easy to do on a windows box, should not be too hard on a Pi, if you have the cables and a USB hub for fan out. I have a Pi and can give it a go are you using Raspbian?

      • Arnold Diaz says:

        Yes, it has Raspbian. I’m very new to Pi and Linux. I bought the Pi for my daughter’s science class but she never used it. I downloaded an install script from Indyham to get Fldigi on the Pi but a bad URL stopped the script. I e-mailed the author and he has resolved the script issue to I’ll give it another go tomorrow.

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