In article om,
"Bruce Raymond" wrote:

Thanks for the reply. I'm actually interested in the version
of the formula (Rl = Vcc^2 / 2Pout) listed on page 2.33
of "Experimental Methods in RF Design", by Wes Hayward, ...
(excellent book).

SNIP
It seems that the formula should be adjusted to account
for the conduction angle, e.g. Rl should be smaller by at
least a factor of 2 to compensate for the conduction
angle. What am I missing?


You are missing the effect of the tuned circuit. Class C operation means
that the output transistor(s) are turned on for only part of a cycle and
thus feed energy into the tuned circuit during part of a cycle. However,
the energy stored in the tuned circuit is large enough to maintain the
output voltage through the complete cycle. Thus the formula does not
need to kow about the conduction angle.
Tink about puching a child on a swing. The person pushing is the output
transistor and the child on the swing the tuned circuit. The person
provides small pushes for a very short part of the complete swing cycle
but they do it at just the right times and the total energy in the
system (how high the child swings) builds up and the swing executes
complete cycles even though it is only pushed for a few degrees at the
back of its swing.
Brian.