38 58 10.92 N,75 52 0.00 W,Highland Aerosports, Ridgely,
Maryland, USA

The PTT
here. These are advertised for FT-270 FT-270R FT-270E FT-277R. They have a
threaded portion at the end of the plug, but the plug worked fine in my FT-250.
There are other models that would likely do better for the FT-250 and other
Yaesu/Vertex radios without the screw in fitting
here and
here.

They are shipped from the US. I got mine quite quickly. The microphone and the
switch are in one unit and the earpiece is on the other wire. I don't know yet
if the wires are lone enough to reach the radio in the Covert harness. It is a
two wire operation.

You would have to take your hand off the base tube to speak by pressing the
button on the microphone which you would clip near from mouth (just how is not
clear to me yet). There is a plastic earpiece that connects to the audio wire,
which also has a clip.