Steve Nosko wrote:
I paraphrase / quote the quote:
Power reflected from a mismatch back into the PA is not absorbed there.
He writes:
"when the pi-network tank is tuned to resonance, a virtual
short circuit to rearward traveling waves is created at the input
of the network. Consequently, instead of the reflected power
reaching the tubes of the amplifier, it is totally re-reflected
toward the load by the virtual short "

Hank, I'm sorry, but I believe this is not correct as stated. The word
"totally", I believe is misleading and contrary to what I think all will
agree. Namely that there MUST be SOME real part (although the true amount
is disputed here) to the Zout of the PA and therefore SOME power MUST be
absorbed there. I believe the point of contention truely is just how much
is absorbed and how much is reflected...

Steve, what you are missing is that the match point is not at the transmitter
terminals and reflections indeed do flow into the transmitter terminals. The
match point is between the tube finals and the input to the pi-net tuning
section. There are zero reflections between the input of the pi-net tuning
section and the tube finals. This is what Walter Maxwell was saying. The
"input of the network" that he is talking about is the wire between the
tube finals and the built-in pi-net tuning section and, indeed in a properly
tuned transmitter, there will be no reflections at that point which was
commonly known as a "Zg-match point".

All of Walt's writings assumed a Zg-match internal in the tube transmitter
at which all reflections were canceled. We hashed that out about 20 years
ago. That's when I first communicated with Walt through snailmail.
--
73, Cecil http://www.qsl.net/w5dxp



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