"Tom Bruhns" wrote
"Reg Edwards" wrote

I didn't say they were unimportant.
I said they served only to add to the
confusion when considering operation of the usual amateur installation
when
the generator internal resistance is unknown.

Indeed, and not only that, the generator (ham transmitter) is commonly
neither a linear system nor time invariant. Also, maximum power
(conjugate-matched load) from a linear generator is generally not the
most efficient case. A great many generators and amplifiers are
distincly NOT designed to deliver power to a matched load, but rather
to deliver power efficiently to a specific load which is mismatched
with respect to the output impedance of the generator/amplifier.

There are times when knowing that a generator is a linear 50 ohm
source (within some small tolerance) is important--I deal with them
all the time in the work I do--but in a typical ham transmitter
application, that's very seldom if ever the case.

====================================
Tom, To add a bit more -

50-ohm generators as used in laboratories (so that measured reflexion loss,
mismatch loss etc, mean something) are effectively constant voltage
generators in series with a 50-ohms resistor, or constant current generators
in shunt with a 50-ohm resistor. They may be followed by an ampifier whose
output impedance is held constant at 50-ohms by some automatic means. None
of these circuits bear much resemblance to a pair of 807's and a tuned tank.

The best that can be said about Rg of the usual HF radio transmitter is that
Rg is indeterminate. IT EVEN VARIES AS THE LOAD IMPEDANCE IS CHANGED which
most of the Guru's contributing to this newsgroup appear to be unaware of or
at least choose to disregard. So what does "adjusting RL to equal Rg" mean?
To use it in a description of feeder + antenna behaviour further propagates
myths, including those surrounding SWR, forward power, reflected power, SWR
meters, etc.

Does Terman ever bother to mention Rg of a Tx PA? If he doesn't it can't
matter very much to him. The ARRL handbook, when numerically designing a
transistor linear HF PA, makes no mention of Rg.
----
Reg, G4FGQ