Evan,
With your observations and suggestions I am quite sure now that my Q5 turned his head away when I was trying to PTT trigger the PA for the first time from an unmodified QDX.? But I have not noticed that.? Although I used a reduced output power.? My bad.? As for your suggestion about adding a P-channel MOSFET, I have an intention to add it at the PTT line input of the PA.? Since the QDX has a possibility to use a zero Ohm PTT line /PTT instead of a PTT +5V.
73 Bojan S53DZ