WARNING! I use the sinusoidal steady state assumptions for this
explanation, this means that all reflection transients have died out and the
input signal is not changing. These are generally good assumptions for
general use that does not depend on signal changing on a time scale similar
to the reflection period, like radar or fast scan tv.... for cw, am, and
even ssb in amateur sized systems these are generally very good and yeild
answers that are more than adequate to answer problems like this.

given the above its very simple. look at the coax connector as if it was a
connector on a black box, there are no reflections. period. the input of
the black box looks like a simple linear impedance.

the procedure to find out how it affects your pi network is this: use your
favorite circuit modeling program and model the linear and output network to
whatever degree of detail you see fit. attach a load of 50+j0 and determine
currents and voltages in the matching network. (note that you will have to
include real world losses in the inductors and capacitors if you want to
calculate power dissipation in them). change load to however bad a
condition you want to model and compare currents and voltages to the 50 ohm
case. this will show you if more or less power is lost in the matching
network. if you have modeled a tube or fet with real world parameters it
will also tell you if it's dissipation goes up or down.


"Henry Kolesnik" wrote in message
. ..
I'm probably not the only one that is getting an adequate fill of facts,
opinions and quotes. I have only one request. Does anyone have
verifiable
and repeatable evidence that a properly tuned pi network final amplifier
without a tuner does or does not dissipate power when there are
reflections?
If they do can they please direct us to the source or give us an easliy
understandable write up.
tnx
--
73
Hank WD5JFR

"alhearn" wrote in message
om...
"Steve Nosko" wrote in message
...
OH! NO! Vortex vs. Bernoulli

Actually, it's Circulation vs. Newtonian vs. Bernoulli -- all three
are different mathmatical means of describing accurately and precisely
what happens when a airfoil produces lift. Actually each is simply a
different way of expressing exactly the same thing, but none of them
translates well to a real-life understanding of the concept. One of
the problems is that causes and effects get confused and
oversimplified by the math.

Much the same with reflections, transmission lines, and impedance
matching. While reflections do indeed exist on transmission lines when
mismatched to a source or load, they simply create standing waves.
Standing waves create non-optimum impedances depending on the
characteristics and length of the line. These impedances interact with
source and load impedances in very predictable and calculated ways.
Efficiency of power transfer is then determined by optimizing the
matching of these impedances. Optimimizing impedances then eliminates
reflections --- a circle of causes and effects.

Mathmatically, it's more expedient to skip much of the in-between
cause-and-effect stuff, and jump directly to describing the entire
process as a direct relationship between reflections and power
transfer -- which causes problems when attempting to visualize or
explain the process -- because that's not the way it really works.
It's not quite that simple and direct.

A standard SWR meter is a good example. It can't conveniently measure
reflections OR standing waves, so it measures mismatch. Since
everything is directly related, it could be said that it measures
reflections -- but it really doesn't. So, it doesn't really matter
unless you try to understand how the meter works in terms of how it
measures reflections or standing waves.

Al