On Jun 14, 9:00*pm, walt wrote:
In his Nov 1991 QST article Warren Bruene, W5OLY, used what I believe
is a similar procedure, in which he claims he measured the Rs that he
called the 'source impedance' of the RF amp. *He used his measurements
in asserting that because his Rs didn't equal RL there could be no
conjugate match when the source is an RF power amp. I have never
believed his procedure and measurements were valid, and I still don't.

IMO, the error that Bruene made is similar in concept to the some of
the errors being made here in this thread. Many people assume that a
simple reflection is the only way to change the direction and momentum
of an EM wave in a transmission line. In "Reflections", Sec 4.3,
Reflection Mechanics of Stub Matching, you describe the role of wave
cancellation associated with interference as a mechanism for
redistributing reflected energy back toward the load. You said, "Wave
interference between these two complimentary waves at the stub point
causes a cancellation of energy flow in the direction toward the
generator." It seems obvious to me that your "virtual short"
reflection at a Z0-match point is a combination of ordinary wave
reflection and interference patterns adding up to zero energy flowing
toward the source. Obviously, interference can also happen inside a
source.

Redistribution of energy can occur associated with destructive/
constructive interference inside the source and has an effect on the V/
I ratios, i.e. on the impedances. Bruene's pinging method completely
ignores the role of interference at the source. The Z = (Vfor+Vref)/
(Ifor+Iref) impedance for coherent waves may be a completely different
value than for the non-coherent pinging waves.
--
73, Cecil, w5dxp.com