Owen Duffy wrote:
"It is my view thatthe statement "Because the amplifier was adjusted to
deliver the maximum available power of 100 watts prior to the resistance
measurement, resistance RLP looking into the plate (upstream from the
network terminals) is also approximately 1400 ohms" is not proven.."

The maximum power transfer theorem is a classic. It has been proven
countless times. It is explained by Terman in his 1955 opus on page 76.
It requires linearity in the area examined. A tuned circuit is often the
linearizer in an r-f amplifier. It eliminates harmonics of the
fundamental frequency so that Ohm`s law prevails across the output
terminals of the device. Thus, it is linear. It makes no difference that
ahead of the linearizer the power source is being pulsed so long as the
pulses don`t appear in the output. We don`t have pulses in the outputs
of our radios feeding our antennas.

When you have a conjugate match, the resistive parts of the source and
load are equal by definition.

Best regards, Richard Harrison, KB5WZI