When I wanted to try out PSK31, I hacked together a cable for my 857D out of spare parts. The 6 Pin Mini DIN connector came from a discarded keyboard and the audio jacks came from a spare auxiliary patch cable.

Before you build one for yourself, note that it is widely recommended that the radio and computer are isolated as not to cause a ground loop. This cable does not provide any isolation. So proceed at your own risk. There are plenty of people that use cables like this without issue–I’m not one of them. I had some issues with the cable, they weren’t the end of the world, but I’ve since upgraded to using a Signalink USB.

857-audio-schematicThe pinout for the data jack is provided in the FT-857D Operator’s Manual (PDF). It is also shown here. One need only connect the data out (1200 bps) from the radio to the computer’s sound input and the data in from the radio to the computer’s sound output. Both of these connections also need to be connected to the ground. Remember, that the diagram here is of the data jack on the back of the radio, make sure the pins you solder to in the connector will mate with the right holes in the jack.

As I said, this cable has worked well for me, but it does have a few drawbacks compared to other methods of connecting a radio and computer. However, this is a very quick* and inexpensive way to try digital modes. If you like it, you may wish to enhance your audio connection.

* This method is quick if you have the parts. If you don’t you’ll need to find them somewhere. If you can’t get your hands on an old PS/2 keyboard or mouse, you can order a 6 pin Mini DIN connector (e.g. Digikey Part #CP-2060-ND).

15 thoughts on “Homebrew Yaesu FT-857D Soundcard Cable

  1. i have an adapter from ps2 to usb can i plug it in and use a usb to my computer to program my 857d?

  2. I’ve built the cable and works fine with my Yeasu FT857d HRD. However I am hearing CAT command clicks on the audio when tracking satellites – any ideas on how to cancel those out?

    • I don’t have any experience with the CAT interface. However, there’s a Redit thread regarding a similar issue (over USB). There are several recommendations there to use RF chokes on all of the cables. That might be a good place to start.

  3. Dear Mr. Reardon:

    Can I syndicate this content for my site? It is great and deserves more exposure. I would of course credit you as author and link back to your website.

    • No, please don’t.

      If you found this post useful, feel free to link to it. Even better, if you have some personal experience with this subject matter, write about that on your site. That will be much more interesting for your readers. If you do that, please let me know so I can check it out.

  4. Would you know if I could use a two ring pin so as to have another contact that would allow me to connect with the PTT? Or does PTT have to be controlled by a CAT cable when in digital mode? I would think that WSJT-X would send a signal then to this pin when a tell the program to transmit.

    • I’m not sure if you’ll be able to trigger the PTT pin through an audio jack. I think you’d need to connect that PTT pin to something else (perhaps some kind of switch), that is controlled via serial port.

      If you find a workable solution, let me know—-I’m curious.

      • Working on this at the moment. 6v transistorized relay that switches ptt to gnd. Driven by RTS from serial.

  5. This looked like a get way to get started with WSJT-X. I already had a CAT cable and thought I just need to connect the audio using this data cable. My goal was to try FT8. So far, I have had mixed results. Receive seems to work fine. Transmit, not so much. That CAT cable will signal the 857D to xmit, but I get no modulation in USB mode which is suggested for FT8. Sound is coming from my sound card and arriving on the “data in” pin, but the 857D does not seem to recognize sound on that pin.

    Has anyone been able to get this cable to work with FT8 and WSJT-X?

    Interestingly, I can split the data out from the sound card and feed to a speaker at the same time. If I hold the mic to the speaker, I can confirm hits on test receivers! How do I get the 857D to recognize the “data in” pin instead of the mic input????


  6. Thanks, I had tried that and every other mode. Long story short. My sound volume and 857 Dig Gain were set too high. Once I lowered them, it started working. It is hard to know with this setup what the problem is! Working well now. Thanks for the post!!!

  7. FT8の受信と制御はPCで出来るようになったので、送信周りについて調べてみました。

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