Jim Kelley wrote:


Cecil Moore wrote:
Following your logic, two people shooting at each
other with identical bullets can do no harm because
the net energy is zero. Care to prove your theory?

How many sources ya got in that example, Cecil? Is that the same to
you? If it is, then I can see why you don't understand.

Couldn't possibly be that you don't understant, huh?

Someone has shot a bullet into an iron wash pot. It ran around
the rim of the pot and changed directions by 180 degrees. Just
as it was changing directions, another bullet was fired from
the same gun. The returning bullet has less energy than the
second bullet. Therefore, the net energy is away from the gun.
Want to stick your head in front of the ricochet bullet
to prove that component energy doesn't matter?
--
73, Cecil http://www.qsl.net/w5dxp

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

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

Gene Fuller wrote:
Note that he uses "imagine", not required, essential, or any other
mandatory word.

You know that I know, "imagine" is just an expression authors use in
the remote event that there might ever be a standing wave without a
forward and reverse wave. All I am asking is for you to provide just
one example where standing waves are not caused by forward and reverse
waves.

You guys mealymouth all around that challenge but NEVER have provided
a decent answer. If you are not going to provide that requested example,
IMO, you have nothing to say worth listening to. So Gene, please, put
up or shut up, and please stop jerking us off.
--
73, Cecil http://www.qsl.net/w5dxp



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Henry Kolesnik wrote:
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.

Hank, when reflected current flows backwards through a pi-net loading
coil, some of the reflected power is dissipated as I^2*R losses in
the coil. Other than that, a properly tuned pi-net causes a match
point that reflects all the reflected energy back toward the load.

If a match point exists in a ham radio antenna system, no reflected
energy will reach the source. This is the great majority of amateur
radio systems and no-reflections-at-the-source is the goal of every
ham. The thing that you are worried about is the unusual case where
reflections are allowed to reach the source.
--
73, Cecil http://www.qsl.net/w5dxp



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Dave wrote:
... 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.

Yep, pretty good for answering the transmitter question. Not so
good for answering the question of what happens between a tuner
and an antenna. One must remember that with your method, one is
dealing with virtual impedances, i.e. voltage to current ratios,
which are themselves a result and not the cause of anything.
--
73, Cecil http://www.qsl.net/w5dxp



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Cecil,

Wow! Struck a nerve. Must be close to the truth.

I have said repeatedly that the alternative technical descriptions
co-exist. I have never said that one "causes" the other. That would be
folly, since we are dealing with math models, not physical cause and effect.

Let me turn the arrow back to you.

Give us one example where forward and reverse waves "cause" a standing
wave, and then prove that it's not the other way 'round.

I am not aware of any credible technical writing on the subject of cause
and effect in these matters, so I am anxiously awaiting your answer.
(Hint: Don't waste your time.)

And as to "shut up", yes, I will now do that.

Until next time . .

73,
Gene
W4SZ

Cecil Moore wrote:
Gene Fuller wrote:

Note that he uses "imagine", not required, essential, or any other
mandatory word.


You know that I know, "imagine" is just an expression authors use in
the remote event that there might ever be a standing wave without a
forward and reverse wave. All I am asking is for you to provide just
one example where standing waves are not caused by forward and reverse
waves.

You guys mealymouth all around that challenge but NEVER have provided
a decent answer. If you are not going to provide that requested example,
IMO, you have nothing to say worth listening to. So Gene, please, put
up or shut up, and please stop jerking us off.
--
73, Cecil http://www.qsl.net/w5dxp



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Cecil Moore wrote:

Jim Kelley wrote:


Cecil Moore wrote:
Following your logic, two people shooting at each
other with identical bullets can do no harm because
the net energy is zero. Care to prove your theory?

How many sources ya got in that example, Cecil? Is that the same to
you? If it is, then I can see why you don't understand.

Couldn't possibly be that you don't understant, huh?

Bullets and radio waves? No. Matter behaves differently than do
electromagnetic waves. I'm quite confident about that.

73, Jim AC6XG

Gene Fuller wrote:
Give us one example where forward and reverse waves "cause" a standing
wave, and then prove that it's not the other way 'round.

Too easy, Gene. Do a web search. *ALL* demonstrations of standing waves
on the web using javascript have the standing wave *caused* by superposition
of a forward wave and a reverse wave. There are hundreds, if not thousands,
of examples. If standing waves could exist without forward and reflected waves,
don't you think someone of your own steady-state cult would have provided an
example by now?

Again, I challenge you (or anyone else) to provide an example of standing
waves in a transmission line without forward-traveling and rearward-
traveling waves. Is just one example, one tiny example, of what you are
asserting, too much to ask? Apparently it is.
--
73, Cecil http://www.qsl.net/w5dxp



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Reg, enjoyed reading your reply, thanks.
73 Gary N4AST