That was cya for us.? I am interested in hearing why you don't? include one.? Is there a reason?
Originally I believed the BS170s in QDX/QMX would see less drain voltage anyway than in a QCX (with it's three parallel BS170) because QDX/QMX has a different PA design, it is push-pull so the voltages are half. And a QCX doesn't have zener diodes. Again QCX is a different design to yours because QCX is Class E.?
The capacitance of the diode could affect the LPF. Furthermore since the capacitance may vary with the RF cycle it may increase the harmonic content. It all would require some non-trivial testing to determine conclusively that there are no I'll effects. As yet I have tested QDX/QMX into shorts and open loads and it doesn't generate higher than spec voltages at the BS170 drains. As far as I'm aware nobody has yet demonstrated a load that can show more than +60V on the drains. Soz frankly it didn't become the highest priority for me among many competing priorities.?
QMX in any case has SWR protection and envelope shaping, and the SWR protection will protect the BS170s in any event. So it's really only QDX we're talking about.?
On QDX (not QMX) there's also the question of the very short dI/dT spike caused by the FT37-43 choke but IF that is an issue (also debatable) the better solution for that would be a small conventional diode across the choke, which has also been discussed here.?
