I have shifted the following post to this thread where it fits the
context perfectly:

On Sun, 30 May 2010 06:59:58 -0700 (PDT), K1TTT
wrote:

does it really matter what the mechanism of generating the heat is?
the fact that there is heat generated in the plate means there is
energy lost from the electrons, be it due to impinging on the plate
mechanically or due to the metal resistance it is still a loss of
energy. And since there is more heat when there is more plate current
we can model it as a real resistance. The only question is then, is
it linear or not. that should be a 'relatively' simple measurement,
and one that has likely been done by a researcher somewhere along the
line.

Yes.

This post is sufficiently informing for many. Others may take its
lead and derive EXACTLY how much resistance, heat, power from the data
provided by Walt and confirm the bench experience of real resistance
within the source.

This response quoted above also corrects my mis-observation of my
having the only perception of this universally experienced phenomenon.
By count, we are up to two who acknowledge what is obvious.

73's
Richard Clark, KB7QHC