Cecil,

It seems that you on purpose remove/ignore things that you don't like,
but (you know) are true.

A CLC pi filter doesn't know the difference between:

1. 100 Ohms lumped circuit load
2. RC = +0.33333 (for 50 Ohms reference)
3. VSWR = 3 (voltage minimum, for a 300 Ohms reference)

It seems you don't want to notice that.

That it is convenient to use transmission line theory to calculate the
load as seen by a PA when transmission line sections are involved, is
OK, I didn't deny that.

That lumped circuit theory has limitations is fully understood.
Frequently transmission line effects are modelled using parasitic L
and C additions yielding accurate models valid up to GHz frequencies
(depending on the size of the component). We are below 30 MHz (for
this topic).

Here the experience of the Engineer comes into play: when you can use
a lumped circuit model and when you need to use transmission line
models (the particle/wave issue is similar)?

A helical inductor of an antenna no longer small w.r.t. wavelength may
be better modelled with transmission line theory, but that is OT.
Even the L of the CLC filter, you can model with a lumped circuit
equivalent with more than sufficient accuracy. This is daily business
for manufacturers of inductive components.

Generally, converting results from transmission line models to
impedance in combination with lumped circuit theory to calculate the
load as seen by the active device, is daily practice. Especially here,
as we are dealing with narrow band signals and don't have to model the
behavior for harmonics. But for some reason you don't want to see
that, and you elevate transmission line theory to a goal.

So again, once you did the conversion to Z, you no longer have to
worry about transmission line issues in the load or cabling (including
reflection coefficient) when treating your PA's CLC pi filter.

Now speed of light becomes important in a CLC pi filter for a HF PA,
when becomes "Gaussian" of importance (and may lose all the readers of
this topic)?

With kind regards,



Wim
PA3DJS
www.tetech.nl