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Old March 20th 07, 10:06 PM posted to rec.radio.amateur.antenna
Owen Duffy Owen Duffy is offline
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First recorded activity by RadioBanter: Dec 2006
Posts: 1,169
Default Revisiting the Power Explanation

Cecil Moore wrote in news:7iYLh.73$Kd3.72
@newssvr27.news.prodigy.net:

Gene needs to tell us how the TV modulation that
causes ghosting makes its predictable round trips
to the source and back without the aid of the
reverse traveling wave.


Talk about echoes!

Cecil, at the time of writing, you have made 4 of the 7 responses to
Walt's posts, and there is nothing in what you have said that you haven't
said recently.

The language from various posters like:

"Some of the posters apparently are unable..."

"Some would say..."

"people obviously don't understand..."

"How can you possibly deny..."

doesn't seem to me the language of convicing arguments, much less proof,
from either side. They seem more a sign of the posters frustration, but
not otherwise convincing.

My guess is that this discussion will not converge on a convincing
outcome.

If the past is any indicator, just when agreement of two or three people
looks likely, someone will inject some noise like lets start dealing with
time domain and transient issues to prove that steady state analysis is
invalid in the practical sense, or this needs a photon explanation with
reference to a text no one is likely to have. It as though those posters
intended to wreck logical development and conclusion. Ah, but that is
USENET!

The basis of the assertion that a PA is naturally or magically conjugate
matched as a necessary consequence of adjustment or design for maximum
power output is based on an leveraging the Maximum Power Transfer Theorem
which depends on a linear source. I don't recall seeing experimental
results to convincingly demonstrate that the PA is a linear source,
though I have seen those that suggest otherwise. If the source cannot be
proven to be sufficiently close to a linear source, then the basis for
arguing the implicit conjugate match dissolves.

No one has yet come up with a quantitative proof that in the general case
PAs of all kinds have an equivalent source impedance the conjugate of
their load, nor convincing experiments that would place bounds on the
reflection coefficient looking into the PA for practical transmitters.

No one has demonstrated that using equivalent impedances etc is not a
valid analysis of the steady state behaviour.

Owen