This technique was common with npn power amplifiers. It's generally not employed with mosfet finals. I don't recall myself ever damaging a qrp mosfet final. Whether a zener even aids survival of mosfet finals maybe someone else can answer.?
As for economics bs170 devices are pennies instead of multiple dollars for few watt npn. Also zener diodes may be more scarce now.?
Yes I have transmitted into the wrong antenna before. Another approach is using a efhw and first insuring it's connected.?
Curt
