"Walter Maxwell" wrote
The source resistance appearing at the output of either a Class B or C
amplifier is R = E/I, where E is the peak voltage at the output terminals
and I is the peak current at the output. Or RMS values can also be
used.Since E/I is simply a ratio, R is also a ratio. And we know that a
ratio cannot dissipate power, or turn electrical energy into heat, thus the
output resistance R is non-dissipative. I have made many measurements that
prove this. It is also the reason why reflected power does not dissipate in
the tubes, because it never reaches the tubes. The reflected power simply
causes a mismatch to the source, causing the source to deliver less power
than it would if there were no mismatch.
__________

If the source resistance of a tuned r-f PA stage was truly non-dissipative,
and the tx simply supplied less power into poor matches, how would that
explain the catastrophic failures to the output circuit components often
seen when high power transmitters operate without suitable SWR protection
into highly mismatched loads?

Another reality is that r-f power from two co-sited, tuned transmitters on
two frequencies in the same band can be present in each others output stage
due to antenna coupling, which causes r-f intermodulation between them. The
non-linear (mixing) process occurs at the active PA stage. If reflected
(reverse) r-f energy never reaches the PA stage as you assert, then how
could this IM generation occur?

RF