On Mar 8, 1:27 am, Dave wrote:
Owen Duffy wrote:

SNIPPED

The question is can the plate (or the whole transmitter for that matter)
be accurately replaced by an equivalent series circuit of a fixed voltage
generator and fixed equivalent series resistance (independent of load).

SNIPPED

The answer is NO!!

Power Amplifiers are not linear devices! [Regardless of manufacturer's claims].

My AL-80B puts out ~850 watts with ~1300 watts input. IF a conjugate match
existed the output would be ~650 watts. The Zo of the 3-500 varies depending on
the phase of the pulse signal. The amplifier provides a pulse of energy into the
tuned circuit, tank circuit, tuner, antenna, where the reactances maintain the
current/voltage under resonant conditions.

My understanding is that reflected energy is also coupled into the tuned
circuits. The active device, power amplifier, may be cutoff, saturated, or
somewhere on the active load line. The energy in the tuned circuit will increase
the Vmax and/or Imax depending on the circuit QL. This increase in stored energy
provides the extra stress on the active device. If the QL 10, nominal design
value, then 90% of the reflected energy is re-reflected back towards the load.
The missing 10% produces heat in the tuned circuit.

Devices that operate from saturation to cutoff are by definition NON-LINEAR.

The tuned circuits store both forward and reflected energy. Ultimately all the
power is radiated, either as a rf field or as heat.

Sorry Dave, the statements in your above post indicates a common
misunderstanding of the operation of an RF power amplifier.

With the possibility that you will consider what I'm about to say is
in the 'he said she said' category, I'd still like for you to review
some of my writings, consider them seriously, and then we'll have
another conversation on the subject. Perhaps I can convince you that
some of your statements are just plain wrong--if not, then we both
simply go our separate ways and believe what we want.

One paper I'd like you to review is Chapter 19 in Reflections 2, also
published in QEX. (I'm now in a hotel in Jax, FL, awaiting spinal
surgery, so I'm not at home where I can obtain the references for
you.) Then I'd also like for you to review Chapter 19A that will
appear in Reflections 3. However, you can find these chapters on my
web page at www.w2du.com. Chapter 19 is found by clicking on 'Review
Chapters from Reflections 2', and Chapter 19A is found by clicking on
'Preview Chapters from Reflections 3'.

I would like to hear from you after reviewing these two papers. I hope
this will help you understand the reason why some of your statements
are incorrect. If you believe I'm wrong, so be it.

Walt, W2DU