BB FANS

Here's a question that keeps popping up on the net.
I can't find anybody selling headsets for the Binatone PMR radios but I did make one up for an MR500 model some years ago ,but I wonder if anybody would know if the Terrain 550 uses the same wiring ? I know if I could the headset I made years ago I could prove it but I can't remember where I last saw it.

I can't see the helpline being much use as I doubt they have a technical section.

Any ideas ?

After some research they appear to use the same set-up as Icom radios that use the single 2.5mm Stereo plug.

Looking at the plug the tip is the microphone complete with a 3 volt supply.
The next bit of the plug is the speaker and the last part is ground.

Now what I don't know is if the radio has the resistor fitted between the Mic line and ground as the PTT in the Icom works by connecting the ground via a 100 Ohm resistor to the Mic line. I know shorting the two wires activate the PTT.
Also a 100uF capacitor is required in line to the Mic to block the DC voltage.
I have discovered that I can't turn the volume down enough for the phone headset I'm adapting so a volume pot will be required.

I have found quite a few people trying to get headset for the Binatone range without success. It would be interesting to plug an Icom one in to see if it's 100% compatible.