Matt GumbleyA kludgey workaround for the UV-K1 external PTT not working when squelch is off (with F4HWN latest firmware): put the PTT in ONEPUSH mode. You still have to tap the radio’s PTT to start transmitting (then you can let go), but you can speak into your external mic - and press the external PTT to stop transmitting. Better than nothing, I guess - gets that 5W of power away from your head!
USB is not available for transmitting though :(