Footswitch PTT adapter for FT-450d, FT-857

Here’s a really simple footswitch PTT adapter for at least the Yaesu FT-450d and the FT-857d. Any rig compatible with the Yaesu MH-31 fist mic with modular 8 pin (RJ45) connector.

Buy a 0.5m Ethernet extension lead, like this:

(they are all over eBay).

Buy a tattooist foot pedal – about £7, again eBay.

Buy a quarter inch in line jack socket.

Cut the outer insulation of the Ethernet extension lead half way along.

Cut a piece of two core wire the same length as from your cut to the Ethernet plug. Solder to quarter inch socket.

Strip back a bit of insulation from the brown and white lead. Connect to the shield of the quarter inch socket via its wire.

At this point you can cut the green lead in the Ethernet cable to disable the fist mic PTT, or you can leave the green lead in place to allow both the foot switch and the fist mic PTT to control the radio.

If you cut the green lead, connect the rig side of the green wire to the other side of the quarter inch socket. If you left the green lead intact, strip back a bit of insulation and make the same connection.

Long way of saying, the green wire in a standard Ethernet cable is the PTT pin, and the brown and white wire is the ground pin. Ground the PTT pin to key up.

6 thoughts on “Footswitch PTT adapter for FT-450d, FT-857”

  1. Hi OM, Thanks very much for the revelation that the “PTT” line on the FY857D Data socket isn’t a genuine PTT! I was trying to get it to key a transverter (28 MHz to 70 MHz) and wondered why it did not work in FM mode (or USB)! I can easily modify your cable idea to provide a microphone driven PTT output via a short tail to a Phono plug for the transverter key line of course. Just a delay until the Ethernet extender is delivered…
    73 es regards, Ted, G4ELM.

    1. Hi Ted

      I know this is long-delayed, but the data port PTT and the mic port PTT are both inputs to the rig (key up the radio on demand) not outputs.

      From memory there is a jumper in the 857 to allow you to get a keying output line on one of the ports. Can’t remember which, or the details, but it might help you Google the solution.

  2. Hi Tom,
    Thanks very much for publishing this foot switch adaptor which I think is great!
    I would like to build another and incorporate a different mic to make a boom mic.
    Would you know what the wires are in the Ethernet lead I would connect the mic to?
    Thanks in anticipation.
    Richard GW0HDY

    1. Hi Richard

      The pins, with standard Ethernet colours, are:

      DOWN – orange/white
      UP – orange
      5V – green/white
      MIC GND – blue
      MIC – blue/white
      PTT – green
      GND – brown/white
      FAST – brown

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