So, I had to interface an external footswitch to an Icom IC-F6061 being used as a control station (dispatch position) for a customer, and found that the PTT input on the DB25 of the radio does not use the audio from the front panel mic jack. It uses the audio from the external modulation input on the DB25 connector. While this is well and good in some applications, in this instance, it’s just a pain. So, I wrote up a little modification to accommodate a desk microphone plugged into the front mic jack which can be PTT’ed by either the microphone PTT button or the external footswitch.
Here is the PDF of the modification: Icom F5061-6061 Footswitch Mods