On May 24, 6:15*pm, Keith Dysart wrote:
This may be the root of my disagreement. Certainly the output can be
an arbitrarily perfect sine wave, but this simply depends on the
characteristics of the filter and not on whether the system is linear.

Since anything except a class-A amplifier is non-linear and since we
are talking about linear analysis, it seems we need to locate a point
in the system where V is a sine wave, I is a sine wave, and V/I is the
constant impedance at that point. IMO, that is the first point at
which we can use a linear math analysis and maybe that point is what
Walt is talking about. It's certainly not going to be the plate of a
class-C amplifier and it may not even be the load-line of the class-C
amplifier. There is probably some point in an otherwise non-linear
system where a linear analysis becomes possible. I think that point is
what Walt considers to be the linear source point, wherever that point
might be located.

In fact, here is my personal take on the subject. Given an antenna
system that presents 50+j0 ohms looking into 50 ohm coax, the internal
impedance of the source doesn't matter. For any voltage source,
irrespective of the source impedance, if reflected energy doesn't
reach the source, the source impedance doesn't matter (except for
efficiency). Seems to me, the highest efficiency would be achieved by
a source with zero ohms of source impedance.
--
73, Cecil, w5dxp.com