"Richard Clark" wrote
Now if we simply review the historical archive
and ask Geoff himself what the Z of his design was,
we find by his own hand:
RF Output Impedance: 50 Ohms

Let's see, no technical argument, and sources that are
self-contradicting. Whatchagonnado? Punt? :-)
________________

You assume he refers to the source impedance of/at output of the amplifier.
More likely he is following convention and stating the load impedance that
the amplifier was designed to work into.

The source impedance of most transmitters is not published even today. If
it was, probably we wouldn't be having all of this confusion about it, and
its effects.

RF