TX GND access for Yaesu FT857D - cable hack or digirig box?

I ordered the Digirig Mobile and appropriate cords for the FT-857d.
I am going to use the digirig for FT-8 but also want to use other modes with an SDRPlay and MFJ-1708B receiver TR switch. I want to get access to the TX GND pin output for control on the MFJ switch.
Would it be easier to hack the cable or open the digirig box to get to the TX GND line?

If you need to split some of the Digirig signals, I’d go with something like this:

Then depending on your lack of appetite for soldering, you can use something like this to access individual signals:

The digirig works great for FT-8 on the FT-857D!
Unfortunately, I found that the wires in the CAT cable from digirig do not access the TX GND pin. So I ordered an 8 pin mini DIN connector to wire it up myself. I hope it’s not too difficult to solder the thing together. I don’t know how I am with intricate soldering technique. We’ll see!
But your response was helpful in giving me the idea of using that headset splitter. Thanks!

The center pin in MiniDin8 connector can be a challenge to solder. Take care of it first.
Which one is TX GND pin? Here’s the pinout of the CAT cable from FT-8xx kit:


Pins side view (use gap in middle row as reference).


I just sent the diagram. TX GND is lower left.

Ah, right. I couldn’t find any references of that pin being used in the user manual for the transceiver or in any online projects. Had to refer to the schematic in service manual.

This appears to be an output signal - open collector PTT control for external devices similar to that in Digirig. It shorts the externally positive-biased line to the ground when radio transmits.


This line is not used by the Digirig so it’s not connected in the CAT cable.