manual antenna matching in switch mode HF amps??
 

On class C tube PAs one could match a Pi-network by seeking the anode
current minimum.

Is it at all possible to do the same on a switch-mode PA?

The rationale:
- want low power CW TX for ANY any HF band ever
- a carefully balanced push-pull PA output will be low in even
harmonics
(really low, I know from experience)
- I can use MOSFETs capable of taking huge excess I & V
- I'd rather avoid messing with many separate octave filters
- fiddling with many manual controls is OK w/ me

I am rather confident that the 5 poles in TWO separate hand-trimmed Pi-
sections in series between step-up RF transformer and antenna will
provide sufficient (mostly odd-) harmonic suppression. I'd first
switch in a 50-ohm dummy load after the 1st Pi-section, match to it,
then switch in the second Pi + antenna, tune up the 2nd Pi.

Before I start collecting parts for another TX and 2 Pi sections, I'd
like to know if DC drain can be a useful indication for tuning up. I
suspect, but don't know for a fact, that something in SMPAs may make
the old way of tuning up impossible.

Any wisdom on that?

TIA + 73

N1JPR