Roy Lewallen wrote:
There are lots of problems with analyzing waves of average power
bouncing around in a transmission line. I'm sure that every one of them
has been pointed out many, many times in postings directed at Cecil.

And none of them are a problem to explain. If there's energy in a
system and it's not presently coming from the source, then it
exists as forward and reflected wave energy that previously came
from the source (in a single source system). All you need to do
to figure everything out is keep track of all the energy.
--
73, Cecil http://www.qsl.net/w5dxp



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Dilon Earl wrote:
If you have a 100 watt transmitter, the watt meter shows 3 watts
reflected. I deliver 103 watts to the antenna. I now know where the
reflected power go's. But where did it come from? If I could find a
way to have 100 watts reflected I could put 200 watts to the antenna
from a 100 watt transmitter.

The key word is "to", not "accepted by". You can indeed get 200 watts
to (incident upon) the antenna with a 100 watt transmitter. Trouble
is, the antenna only accepts half of that power.

For some reason I need a circulator on my SB-401.

Only if you allow reflected energy to reach your SB-401.

To get max power out my 6146's I need to turn them upside down in a
glass of water? :-)

Only if they are metal.
--
73, Cecil http://www.qsl.net/w5dxp



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"W5DXP" wrote in message
...
Jim Kelley wrote:
You're sourcing and sinking an additional 33.33 watts, and yet the
wattmeter can't discern the difference between this scenario and the 100
watt, single source scenario.

But that sourcing and sinking is occurring *INSIDE* the SGCL(150). The net
power inside SGCL(150) is 100W dissipated, *exactly* like the other
scenario.

Exactly like the other scenario, yeah, like the extra .033 Kw makes no
difference. That's a good one, Cecil :-)

The example illustrates perfectly the shortcomings of the idea of power
flow, as well as some of the faulty conclusions that can be drawn from
measurements made by a directional power meter.

The shortcoming I notice is your sidestepping of the question:

More notable are the shortcomings you _don't_ care to notice.

What happened
to Pref1=25W? It just seems to have disappeared when we turned on
SGCL(150)
and the 33.33W wavefront arrived at the impedance discontinuity. What
could
have possibly made Pref1 disappear?

Hmmmm, never thought about that before. Could wave cancellation be
involved?

73, Jim AC6XG

William E. Sabin wrote:
Ian White, G3SEK wrote:
* The output impedance of the transistor doesn't come into the
story at all - not when characterizing RF power devices that are not
operating in class A. Even the device manufacturer doesn't know or
care what it is. Neither need we.


Tubes and transistor power amplifiers quite oftem use negative feedback
to improve SSB linearity. Improvements of 5 to 10 dB are common. The
negative feedback reduces the internal impedance of the tube and
transistor amplifiers. The tube/transistor data sheets do not consider
this factor.

Again, we usually don't really know or care much about the values of
the internal impedances.

Agreed.

But there is a special case. Voice/music/data tube transmitters
operating at low frequencies have a problem called "sideband clipping"
where the plate tank selectivity may be too sharp and reduces the
modulation bandwidth. The internal impedance tends to broaden the
response at resonance. When designing the tank circuit this effect may
have to be included.

Thanks for that information. A related topic would be the effect of
tank circuit Q on the bandwidth of HF amplifiers; I seem to remember
reading something about, but don't recall what it implied about the
magnitude of the tube internal impedance, as compared with the load
impedance.


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
Editor, 'The VHF/UHF DX Book'
http://www.ifwtech.co.uk/g3sek

Ian,

Thanks for the lowdown. I am saving the message. I looked through the Moto
RF book last night and noticed some specs spell out by what they mean by
output impedance (conjugate of load), while others don't. Newer ones seem to
qualify it. Since the efficiency of these devices is usually around 50%, you
can't tell which is which by looking at the numbers.

I have designed several 6m amplifiers by choosing the parallel load
resistance based solely on VCC and desired PO, and it always worked.

Tam/WB2TT

Roy,

I think I have the complete solution to your 70.7V generator and 1/2 wave
line, but with a finite load. Part of it implies that you are correct. Part
of it seem weird, even though the numbers add up. I analyzed it both as a
circuit element and as a transmission line problem. Kind of long, but I'll
post it if you want to see it.

Tam/WB2TT
"Roy Lewallen" wrote in message
...
There are lots of problems with analyzing waves of average power
bouncing around in a transmission line. I'm sure that every one of them
has been pointed out many, many times in postings directed at Cecil.

Jim Kelley wrote:
"W5DXP" wrote in message
Exactly like the other scenario, yeah, like the extra .033 Kw makes no
difference. That's a good one, Cecil :-)

In the first scenario, the 0.033 Kw was loaded into the system before
steady-state conditions were established. The s-parameter equations
consider the power reflected from a mismatched load as another source
of power in the system. The two scenarios are very similar.

But forget the first scenario. What happens to Pref1 in this scenario?
It takes a 25 joules/sec wave to cancel a 25 joules/sec wave.

Vfwd1(rho) = 35.36V at zero degrees, Ifwd1(rho) = 0.707A at 180 degrees.

Vref2(tau) = 35.36V at 180 degrees, Iref2(tau) = 0.707A at zero degrees.

Each of these rearward-traveling waves contains |35.36V*0.707A| = 25 joules/sec

They superpose to zero. What happens to that 50 joules/sec of rearward-
traveling energy? We already know it winds up in a forward-traveling wave
toward the load. You have already admitted that wave cancellation is
responsible for Pref1 being zero. Waves simply cannot exist without energy.
When waves cease to exist, they are forced to give up their intrinsic energy.
We know that Vref2(tau) is traveling rearward. That's all we need to know.
Vref2(tau) is the same voltage term as s12*a2 in the s-parameter equation.

When b1=0=s11*a1+s12*a2, what happens to |s11*a1|^2 and |s12*a2|^2? We
know that s11*a1 and s12*a2 are rearward-traveling voltages.
--
73, Cecil http://www.qsl.net/w5dxp



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No need, I've done both transient and steady state sinusoidal solutions
for the general case many times. The source impedance dissipation and
power supplied by the source can be entirely determined simply by
replacing the transmission line and terminating impedance with an
impedance equal to that seen looking into the input end of the line. It
becomes a simple, three-component electrical circuit. You can replace
the transmission line and load with any combination of length, Z0, and
load impedance you'd like, as long as the input impedance is the same,
creating just about any amount of "reflected power" you want, without
changing the source dissipation.

The "reflected power" is not dissipated in the source, matched or not.
It's trivial to show that this is true. But people still want to believe.

Roy Lewallen, W7EL

Tarmo Tammaru wrote:
Roy,

I think I have the complete solution to your 70.7V generator and 1/2 wave
line, but with a finite load. Part of it implies that you are correct. Part
of it seem weird, even though the numbers add up. I analyzed it both as a
circuit element and as a transmission line problem. Kind of long, but I'll
post it if you want to see it.

Tam/WB2TT
"Roy Lewallen" wrote in message
...

There are lots of problems with analyzing waves of average power
bouncing around in a transmission line. I'm sure that every one of them
has been pointed out many, many times in postings directed at Cecil.

Roy Lewallen wrote in message ...

What needs to be thrown away is the belief that all impedances are the
ratio of a voltage to a current, along with the notion that only
resistors can have resistance.

Roy Lewallen, W7EL



You have convinced me that you are correct about both of these
points.

Good. Then the effort was worthwhile.


Absolutely.



But i don't think that an antennas impedance will not be affected
by the permeability of the medium that surrounds it. An antennas
input impedance will be different in free space as opposed to being
immersed in water, for example.

Indeed it will.


This indicates to me that the antenna is indeed "matching" 50
Ohms to the impedance of free space, even if it is a different type of
impedance.

That's a leap I'm unable to make or to follow.



Clearly, neither of us are PhDs in EM wave propagation, but water
certainly has a different E versus H impedance than the 377 Ohms of
free-space, which is why the input impedance of the antenna will
change. This is not the same, but similar to how the load on the
secondary will affect the primary impedance of a transformer.



Do you think that the characteristics of a transformer of a
specific turns ratio, gauge wire, and core geometry, will NOT depend
on the core material? I would say definitely it WILL depend on the
material.

Actually, an adequate core shouldn't appear as a significant factor in
transformer performance. Naturally, an inadequate core will adversely
affect it. But I just don't accept that as evidence, let alone "proof"
that an antenna is fundamentally an impedance matching device.



Well, you've already agreed that an antenna/transducer can be
considered one half of a transformer, but what i'm saying is that the
permeability of the core or medium will certainly affect the impedance
of the transducer.

What do you mean by "adequate core"? One that suits your purpose
i suppose. But a material of the wrong permeability will definitely
affect your transformer performance. So the impedance of the core
definitely affects the transformer characteristics, as does the
impedance of the air (or water) between two antennas.



I see that you won't be swayed from your visualization. But hopefully
some of the other readers can see the fallacy of the concept. I think
I've done all I can, so I'll leave this topic now.



You've convinced me that antennas are transducers, which are one
half of a transformer, by giving me logical statements.

But you have not come up with anything to convince me otherwise
on this point, which i don't believe is a fallacy at this time.



*Chuckle* I was just reminded of something that happened years ago, when
my son was a small boy. He learned that I was an engineer, so he
couldn't wait to see the train I drove. After a great deal of repeated,
patient, explanation, I finally got across (I thought) a description of
what I did, and that it had nothing to do with trains. Well, he had
occasion to visit me at work quite a long time later. He kept wandering
off. When I asked why, he explained that he was trying to find where the
train was kept. Yeah, I might not drive trains, but I must have
*something* to do with trains.


I'm not a small boy Roy, and I'm an engineer too. Your NG
inspired sarcasm doesn't change my opinion at all, and cannot even be
compared to logical reasoning.

Roy, thanks for your insight, and you have definitely helped me
out with your strict semantics (sometimes needed, especially in the
engineering world!).

But your need to be always right closes your mind to new ideas
and new learning. This is the sign of someone who claims to know
everything about a subject, which i personally believe to be
impossible, even for such a specialized topic as antennas (actually,
it's quite broad, isn't it?), and even for someone as bright and
knowledgable as you are.


Again, much thanks for your input.


Dr. Slick

On Sat, 19 Jul 2003 10:11:36 -0500, W5DXP
wrote:

Dilon Earl wrote:
If you have a 100 watt transmitter, the watt meter shows 3 watts
reflected. I deliver 103 watts to the antenna. I now know where the
reflected power go's. But where did it come from? If I could find a
way to have 100 watts reflected I could put 200 watts to the antenna
from a 100 watt transmitter.

The key word is "to", not "accepted by". You can indeed get 200 watts
to (incident upon) the antenna with a 100 watt transmitter. Trouble
is, the antenna only accepts half of that power.


Where does the other 100 watts go?

For some reason I need a circulator on my SB-401.

Only if you allow reflected energy to reach your SB-401.

How can I stop it from reaching my SB-401?

Then all ham transmitters should have a circulator?

Roy Lewallen wrote:
The "reflected power" is not dissipated in the source, matched or not.

If reflected energy could not cause over-current/over-voltage
problems in the source there would be no need for protection
circuitry. I once burned up a pair of ARC-5 1625's because my
feedline came unsoldered at the antenna. If there had not been
any reflected power, it would not have happened.
--
73, Cecil http://www.qsl.net/w5dxp



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Dilon Earl wrote:
You can indeed get 200 watts
to (incident upon) the antenna with a 100 watt transmitter. Trouble
is, the antenna only accepts half of that power.

Where does the other 100 watts go?

It is reflected back toward the source. It causes standing waves
and additional losses in the transmission line.

For some reason I need a circulator on my SB-401.

Only if you allow reflected energy to reach your SB-401.

How can I stop it from reaching my SB-401?

Does the SB-401 have an adjustable Pi-net output? If so,
you can adjust it for a Zg-match which will keep reflected
energy from being incident upon the SB-401 amp. If not, you
can use an external antenna tuner.
--
73, Cecil http://www.qsl.net/w5dxp



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W5DXP wrote:
Tarmo Tammaru wrote:
Thanks for the lowdown. I am saving the message. I looked through the Moto
RF book last night and noticed some specs spell out by what they mean by
output impedance (conjugate of load), ...

Hmmmmm, the load is in control of the amp's load line.

In part, of course it is.

The standing bias controls one fixed point on the line.

The load, transformed backward through the output matching network,
controls the slope of the line.

Finally, the drive power controls how far the instantaneous operating
point moves along the line.


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
Editor, 'The VHF/UHF DX Book'
http://www.ifwtech.co.uk/g3sek

The stuff I did point to the actual impedance, not the SWR that does the bad
thing. For instance, a load of 25 Ohms greatly increases the internal
dissipation; a load of 100 Ohms greatly reduces it. If you go too high with
the impedance, you start to saturate the hell out of the device, and other
things happen.

Did you melt the plates on the 1625s or burn out the grids? Your feedline
might have opened an odd multiple of 1/4 wave from the radio.

Tam/WB2TT
"W5DXP" wrote in message
...
Roy Lewallen wrote:
The "reflected power" is not dissipated in the source, matched or not.

If reflected energy could not cause over-current/over-voltage
problems in the source there would be no need for protection
circuitry. I once burned up a pair of ARC-5 1625's because my
feedline came unsoldered at the antenna. If there had not been
any reflected power, it would not have happened.
--
73, Cecil http://www.qsl.net/w5dxp

The haggling, for years, about congugate matching, SWR, forward & reflected
power, silly virtuallty, etc, has gone on long enough.

Only G3SEK, amongst the small minority of the radio population who
contribute to these walls, has a grasp of what it's all about. There are
obviously others who are too busy to waste their time on newsgroups.

But who am I to judge?

INTERNAL IMPEDANCE OF RF POWER AMPLIFIERS

Programs TRIODE1 and TETRODE1 assist with the classical design of tube
(valve) power amplifiers. They are very closely related to each other. A key
design feature, the cathode current operating angle, is an input parameter.

Apart from the drive and input-circuits, they also apply to their lower
power transistor equivalents.

For the benefit of those who may insist on knowing, these two programs are
based on the clssical theoretical analysis by americans Everitt, 1932 (who
was probably not original at that relatively late stage of the thermionic
tube). He was followed by Terman in a more practical but more uncertain
manner in the 1940's. No doubt there have been others. None of them, aware
of their weaknesses, would have wished to be worshipped as little tin Gods.

The basics havn't changed since Ohm, Ampere, Voltaire and Heaviside.

Anyone responding to an enquirer, who feels in need of extra support in his
reply, who refers back to the ancients merely displays his inability to
provide a logical explanation and a lack of underlying understanding.
There's nothing wrong, of course, in a lack of understanding except in
propagating it. (Most enquirers do not have the ancient books or easy access
to the books anyway)

Neither of this pair of programs require a congugate match between internal
impedance and the load. There's nothing magical about 50 ohms. It could be
any value as any appropriately designed SWR meter will assume. I have a
75-ohm model. All is based on assumptions. The only absolute value is SWR
itself which does not depend on Zo or Z load but merely on their ratio.

The only way to determine dynamic internal impedance of a PA is to calculate
it AFTER THE AMPLIFIER HAS BEEN COMPLETELY DESIGNED. It is then too late to
have any effect on design.

Just to satisfy curiosity the dynamic internal resistance of an amplifier is
a calculated output quantity of program TETRODE1. It is of course of no
practical value. In the program it is referred to as the Source Resistance
when looking back into the 50-ohm output socket.
----
=======================
Regards from Reg, G4FGQ
For Free Radio Design Software
go to http://www.g4fgq.com
=======================

Tarmo Tammaru wrote:
Did you melt the plates on the 1625s or burn out the grids?

Melted the plates and smoked the parasitic suppressors. I don't
know how long the feedline was.
--
73, Cecil http://www.qsl.net/w5dxp



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W5DXP wrote:
Ian White, G3SEK wrote:
The load, transformed backward through the output matching network,
controls the slope of the line.

Which is a V/I ratio - which is an impedance. Could this be the impedance
"seen" by the reflected waves transformed through the output matching network?

Specifically, precisely NOT... as apparently you well know (except in
the special case of class A).


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
Editor, 'The VHF/UHF DX Book'
http://www.ifwtech.co.uk/g3sek

Ian White, G3SEK wrote:
W5DXP wrote:
If reflected energy could not cause over-current/over-voltage
problems in the source there would be no need for protection
circuitry. I once burned up a pair of ARC-5 1625's because my
feedline came unsoldered at the antenna. If there had not been
any reflected power, it would not have happened.

Transmitters are damaged *only* by excessive heat dissipation, voltage
or current, all caused by the wrong value of load impedance. Reflections
don't come into it.

Reflections are the *CAUSE* of the wrong value of load impedance. The load
impedance on a transmitter when reflections are allowed to reach the
transmitter is (Vfor+Vref)/(Ifor+Iref). Please note that half the terms
in the impedance equation are reflected terms. Please note that without
the reflected terms, the transmitter would probably be perfectly happy
with the "right" value of impedance at (Vfor/Ifor).

Think what would have happened if you had measured the impedance at the
TX end of your o/c transmission line (very high or very low, depending
on the length) and replaced it with a resistor and inductor/capacitor
giving the same value of R +/- jX.

There's no transmission line, so no traveling waves of anything, and no
reflections - just a transmitter with a very wrong value of load
impedance. The 1625s would have burned up just the same.

Yes they would, but in that case reflections are not the cause of the
impedance. In the first case, reflections are the *CAUSE* of the
impedance that burned up the transmitter. Without the reflections, the
transmitter would see (Vfor/Ifor) as the "right" impedance. With the
reflections, the transmitter sees (Vfor+Vref)/(Ifor+Iref) as the "wrong"
impedance.
--
73, Cecil http://www.qsl.net/w5dxp



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Ian White, G3SEK wrote:

W5DXP wrote:

Ian White, G3SEK wrote:

The load, transformed backward through the output matching network,
controls the slope of the line.

Which is a V/I ratio - which is an impedance. Could this be the impedance
"seen" by the reflected waves transformed through the output matching
network?

Specifically, precisely NOT... as apparently you well know (except in
the special case of class A).

Class-A and combined Class-AB are both linear. The impedance "seen" by
the reflected waves transformed through the output matching network IS
linear. The output matching network acts like a pendulum or flywheel.
--
73, Cecil http://www.qsl.net/w5dxp



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Slick

Dr Slick,
Way back in this thread you alluded to antennas as being
transformers. The more I think about that statement the more I see
it as being fact. Anything that involved coupling which all
antennas do can be drawn as a transformer !
Since the thread migrated all over the place did you feel that
the group agreed with that position?
Regards
Art

Ian White, G3SEK wrote:
Think what would have happened if you had measured the impedance at the
TX end of your o/c transmission line (very high or very low, depending
on the length) and replaced it with a resistor and inductor/capacitor
giving the same value of R +/- jX.

There's no transmission line, so no traveling waves of anything, and no
reflections - just a transmitter with a very wrong value of load
impedance. The 1625s would have burned up just the same.

Yes, 1625's are pretty dumb but hopefully, we are smarter than the 1625's.
Here's more from the IEEE dictionary.

"resistance - (A) That physical property of an element, DEVICE, ...
(B) The real part of impedance. Note: Definitions (A) and (B) are
not equivalent ..."

"resistor - A DEVICE the primary purpose of which is to introduce
resistance into an electric circuit."

"impedance - (B) The ratio of the ... voltage ... to the ...
current ... (C) A physical DEVICE or combination of DEVICES ...
Definition (C) is a second use of 'impedance' and is independent
of definitions (A) and (B)."

"impedor - A DEVICE, the purpose of which is to introduce impedance
into an electric circuit."

In your above example, you changed the circuit from a (B) impedance to
an impedor. Even if the 1625's can't tell the difference, W5DXP can. :-)
Note that I, not the IEEE, capitalized 'DEVICE' in the above definitions.
--
73, Cecil http://www.qsl.net/w5dxp



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Uh, Reg, Voltaire wrote "Candide".
Perhaps you were thinking of Volta, the Italian.
And you forgot Maxwell, Cavendish and Faraday.
All brits, all important to this stew.
Plus a host of others all the way back to Greece and before.
And if more here had gotten as far as Gibbs, we could just write down the
DE's and the BC's and be done in a few lines of math.
But it has been virtually entertaining, don't you think?
73 es gud dx om
H.
NQ5H

ascii limited notation
------------------------
div D = rho (rho is
charge)
curl H - (partial with respect to time) D = J (J is current)
curl E + (partial with respect to time) B = 0
div B = 0

D = epsilon(naught) E
B = mu(naught) H



"Reg Edwards" wrote in message
...

The haggling, for years, about congugate matching, SWR, forward &
reflected
power, silly virtuallty, etc, has gone on long enough.

Only G3SEK, amongst the small minority of the radio population who
contribute to these walls, has a grasp of what it's all about. There are
obviously others who are too busy to waste their time on newsgroups.

But who am I to judge?

INTERNAL IMPEDANCE OF RF POWER AMPLIFIERS

Programs TRIODE1 and TETRODE1 assist with the classical design of tube
(valve) power amplifiers. They are very closely related to each other. A
key
design feature, the cathode current operating angle, is an input
parameter.

Apart from the drive and input-circuits, they also apply to their lower
power transistor equivalents.

For the benefit of those who may insist on knowing, these two programs are
based on the clssical theoretical analysis by americans Everitt, 1932 (who
was probably not original at that relatively late stage of the thermionic
tube). He was followed by Terman in a more practical but more uncertain
manner in the 1940's. No doubt there have been others. None of them, aware
of their weaknesses, would have wished to be worshipped as little tin
Gods.

The basics havn't changed since Ohm, Ampere, Voltaire and Heaviside.

Anyone responding to an enquirer, who feels in need of extra support in
his
reply, who refers back to the ancients merely displays his inability to
provide a logical explanation and a lack of underlying understanding.
There's nothing wrong, of course, in a lack of understanding except in
propagating it. (Most enquirers do not have the ancient books or easy
access
to the books anyway)

Neither of this pair of programs require a congugate match between
internal
impedance and the load. There's nothing magical about 50 ohms. It could be
any value as any appropriately designed SWR meter will assume. I have a
75-ohm model. All is based on assumptions. The only absolute value is SWR
itself which does not depend on Zo or Z load but merely on their ratio.

The only way to determine dynamic internal impedance of a PA is to
calculate
it AFTER THE AMPLIFIER HAS BEEN COMPLETELY DESIGNED. It is then too late
to
have any effect on design.

Just to satisfy curiosity the dynamic internal resistance of an amplifier
is
a calculated output quantity of program TETRODE1. It is of course of no
practical value. In the program it is referred to as the Source Resistance
when looking back into the 50-ohm output socket.
----
=======================
Regards from Reg, G4FGQ
For Free Radio Design Software
go to http://www.g4fgq.com
=======================

Hey, that's cool. Been a ham for 46 years, made it through Air Force
technical school, got a BSEE degree, and spent over 30 years doing
circuit design without ever once coming across the term "impedor". And
there it was, right in the IEEE dictionary. This newsgroup is sure
educational!

Roy Lewallen, W7EL

W5DXP wrote:
. . .

"impedor - A DEVICE, the purpose of which is to introduce impedance
into an electric circuit."

In your above example, you changed the circuit from a (B) impedance to
an impedor. Even if the 1625's can't tell the difference, W5DXP can. :-)
Note that I, not the IEEE, capitalized 'DEVICE' in the above definitions.

H. wrote,

Uh, Reg, Voltaire wrote "Candide".
Perhaps you were thinking of Volta, the Italian.
And you forgot Maxwell, Cavendish and Faraday.
All brits, all important to this stew.
Plus a host of others all the way back to Greece and before.
And if more here had gotten as far as Gibbs, we could just write down the
DE's and the BC's and be done in a few lines of math.
But it has been virtually entertaining, don't you think?
73 es gud dx om
H.
NQ5H


Reg likes to intentionally put things like that into his posts to
put us all on. If you read much Thackery, who made a good
living at one time writing about English con artists, you'll know
it's a part of the British national character.
73,
Tom Donaly, KA6RUH

Dave Shrader wrote:
How does the wrong load impedance comes into existence?
Is it not caused by the mismatch?

Yep, the mismatch causes reflected waves which, in turn, cause the wrong
load impedance. It's easy to see in the following thought experiment.

200W source---one second long 50 ohm lossless feedline-----open

The source will output 100V at 2A for two seconds from key down and
be perfectly happy. The "wrong" impedance arrives exactly with the
reflected wave after two seconds. The center of the steady-state SWR
circle is the "right" impedance and therefore will not exist after two
seconds.
--
73, Cecil http://www.qsl.net/w5dxp



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Roy Lewallen wrote:
Hey, that's cool. Been a ham for 46 years, made it through Air Force
technical school, got a BSEE degree, and spent over 30 years doing
circuit design without ever once coming across the term "impedor". And
there it was, right in the IEEE dictionary. This newsgroup is sure
educational!

So what are you going to do with your new found knowledge? :-)
--
73, Cecil http://www.qsl.net/w5dxp



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Yeah, but it gave me a chance to mouth off.
And then I forgot Ben Franklin!
Anybody who'll fly a kite in a thunderstorm deserves mention.
I visited Cambridge once; Newton to Hawking,
Reg is in good company.
73
H.

"Tdonaly" wrote in message
...
H. wrote,

Uh, Reg, Voltaire wrote "Candide".
Perhaps you were thinking of Volta, the Italian.
And you forgot Maxwell, Cavendish and Faraday.
All brits, all important to this stew.
Plus a host of others all the way back to Greece and before.
And if more here had gotten as far as Gibbs, we could just write down the
DE's and the BC's and be done in a few lines of math.
But it has been virtually entertaining, don't you think?
73 es gud dx om
H.
NQ5H


Reg likes to intentionally put things like that into his posts to
put us all on. If you read much Thackery, who made a good
living at one time writing about English con artists, you'll know
it's a part of the British national character.
73,
Tom Donaly, KA6RUH

I wrote,

Reg likes to intentionally put things like that into his posts to
put us all on. If you read much Thackery, who made a good
living at one time writing about English con artists, you'll know
it's a part of the British national character.
73,
Tom Donaly, KA6RUH


I misspelled "Thackeray." I expect he'll forgive me, though.
73,
Tom Donaly, KA6RUH

W5DXP wrote:

William E. Sabin wrote:

If the transmission line input impedance is replaced with a lumped LCR
circuit, then confusion disappears and we have a conventional problem
in AC circuit analysis.


Some confusion disappears. Some additional confusion arises. It should
be recognized that replacing a V/I impedance with an impedor is a shortcut
and doesn't necessarily represent reality. Math models certainly do not
control reality. For instance, ghosting is not the same in the two cases.
A TDR will not give the same results.

I give up.

Bill W0IYH

Who, Reg or Thackeray?
;^)))
"Tdonaly" wrote in message
...
I wrote,

Reg likes to intentionally put things like that into his posts to
put us all on. If you read much Thackery, who made a good
living at one time writing about English con artists, you'll know
it's a part of the British national character.
73,
Tom Donaly, KA6RUH


I misspelled "Thackeray." I expect he'll forgive me, though.
73,
Tom Donaly, KA6RUH

Roy Lewallen wrote:

Hey, that's cool. Been a ham for 46 years, made it through Air Force
technical school, got a BSEE degree, and spent over 30 years doing
circuit design without ever once coming across the term "impedor". And
there it was, right in the IEEE dictionary. This newsgroup is sure
educational!

Maybe you missed this one also: "reactor - a device, the primary purpose
of which is to introduce reactance into a circuit."

If you buy 'resistor', why not 'reactor' and 'impedor'? Same concept.
--
73, Cecil http://www.qsl.net/w5dxp



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Bill wrote,

W5DXP wrote:

William E. Sabin wrote:

If the transmission line input impedance is replaced with a lumped LCR
circuit, then confusion disappears and we have a conventional problem
in AC circuit analysis.


Some confusion disappears. Some additional confusion arises. It should
be recognized that replacing a V/I impedance with an impedor is a shortcut
and doesn't necessarily represent reality. Math models certainly do not
control reality. For instance, ghosting is not the same in the two cases.
A TDR will not give the same results.

I give up.

Bill W0IYH


I would like to know why Cecil, for instance, uses pulses, as in a TDR, in
order
to argue a steady state point. Impedance is normally defined for any "impedor"

at only one frequency at a time. A single pulse, according to Mr. Fourier, can

be characterized with a component at all frequencies. So which frequency and
which impedance are you talking about, Cecil, when you change the subject from
steady state to the time domain?
Secondly, math models are descriptions. Their purpose has never been to
control
anything. Moreover, no one except you, Cecil has ever implied that anyone
thought
they were. Do I detect a straw man here?
73,
Tom Donaly, KA6RUH

On Sat, 19 Jul 2003 15:25:47 -0500, W5DXP
wrote:

Dilon Earl wrote:
You can indeed get 200 watts
to (incident upon) the antenna with a 100 watt transmitter. Trouble
is, the antenna only accepts half of that power.

Where does the other 100 watts go?

It is reflected back toward the source. It causes standing waves
and additional losses in the transmission line.

For some reason I need a circulator on my SB-401.

Only if you allow reflected energy to reach your SB-401.

How can I stop it from reaching my SB-401?

Does the SB-401 have an adjustable Pi-net output? If so,
you can adjust it for a Zg-match which will keep reflected
energy from being incident upon the SB-401 amp. If not, you
can use an external antenna tuner.

So I can change my reflected power, or SWR by adjusting my Pi-net
output?

I have never seen either one change when changing my load and tune
controls.

W5DXP wrote:
Even if the 1625's can't tell the difference, W5DXP can. :-)

That's the whole point - the *only* difference is a conceptual one that
exists inside your mind.

It has no reality out here in the physical world of measuring
instruments and engineering, which is the place where the 1625s live
(and sometimes die).


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
Editor, 'The VHF/UHF DX Book'
http://www.ifwtech.co.uk/g3sek

William E. Sabin wrote:
W5DXP wrote:

William E. Sabin wrote:

If the transmission line input impedance is replaced with a lumped
LCR circuit, then confusion disappears and we have a conventional
problem in AC circuit analysis.

Yes! That principle of impedance substitution is so simple, so
fundamental, some people never notice it's there at all.

Some confusion disappears. Some additional confusion arises. It
should
be recognized that replacing a V/I impedance with an impedor is a shortcut
and doesn't necessarily represent reality. Math models certainly do not
control reality. For instance, ghosting is not the same in the two cases.
A TDR will not give the same results.

I give up.

Me too, Bill... I've been following this in the breaks from a hard
working weekend, but now the working week is about to start all over
again. Enough already.


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
Editor, 'The VHF/UHF DX Book'
http://www.ifwtech.co.uk/g3sek

On Sun, 20 Jul 2003 22:10:26 GMT, Dilon Earl
wrote:
If you have three Watts reflected, it came from the transmitter and in
fact never left it, it simply turned to heat. The meter is indicating
a condition, not forcing it. A fever thermometer in your mouth will
tell you that you have a temperature in excess of the surrounding
environment (a clear mismatch except for rare summer days) and yet the
thermometer is not responsible for your fever (Thoreau once offered
that we were more comfortable before the thermometer's invention).

Ok, if it never left the transmitter, why or would there be a loss in
the feedline due to high reflected power?

The 3W you measured was/is at the transmitter end of that feedline, it
could have been 30W at the load, but the feedline burnt up 27W as it
came back (it also burnt up the same proportion of that power going
forward). One of the truisms of measuring SWR is that a lossy line
will make the worst of load reflections look better.

In a sense you could say that a lossy line is cooling your
transmitter. Think of it as a remote heat sink. ;-)

SWR can be thought of as being derived from an equivalent lumped load
attached directly at the antenna jack (it is) or as from the long
system variable extended across space and storing energy (it is). You
should judge the character of an answer as needing to respond to BOTH
views in proportion to actual circumstances. Neither is independently
correct to the exclusion of the other (and this is why some discussion
devolves into pulses).


You can use a circulator to heat a dummy load if you wish, or you
could use a tuner to reflect that power back to the antenna. You may
well wonder why a circulator was offered in the first place.
Rhetorical gamesmanship is the answer which has nothing to do with
offering any real solution to you.

I didn't see where a circulator had anything to do with my original
question. My SB-401 doesn't have one.

Nobody uses one. I would hedge that call with saying they are found
in "some" repeater installations, but only if the designer has the
sheckles (or savvy) to rummage one up.


Well, perhaps too much explanation, you can certainly survey the other
postings for their entertainment value in the form of cut-and-paste
theory or equipment operator myths.

73's
Richard Clark, KB7QHC

Thanks for taking the time to answer my questions. Its too bad a
newbie with a few simple questions can't ask them and get answers to
them. 99% of the answers made no sense to me. But I guess if they
did, There wouldn't be reason for me to ask my simple questions?

Hi Dilon,

Sometimes that is because they expect you to reference Google's
archives of yesterday's posts. The problem there is that same archive
is full of the same baloney offered to the last one they expected to
reference the archives. Others will sometimes offer a significant
search term that leads to a lengthy treatment quickly - the remainder
don't have a clue and insist on proving it the hard way.

Finding real, actual data, experience, or theory is as rare here as it
is anywhere when the price is nothing and the cost is high. Through
"lurking" (reading, but rarely jumping into the game) over an
extended period, you get to read personalities and observe personal
weaknesses. If you looked back up the chain of responses and side
threads, you should observe some correlations to answers offered in
good faith (even if they were less than eloquent, a bit off the mark,
or lost themselves).

Rarely is one blown off for simply being a newbie, but if anyone
marched in here saying "I don't know how this works, but I can prove
it ain't the way everyone says" - expect fried critic for dinner.

By-the-by. I noticed you referred to tube equipment along the way, or
simply took up a ride with strangers (dangerous habit). Tubes exhibit
the same problems with heat as transistors do. As this topic is
hardly closed (if you lurk or participate, you will see your same
question offered again); you should observe how denials emerge where a
tube is somehow immune.

The proper expression would be tubes are somewhat immune and in fact
are far more survivable than some transistor sets facing the same
mismatches. Tubes also have a vastly larger surface area (of the
plate) and thermal mass which offers much more resilience (the small
junction meltdown happens faster) and they glow cherry red to prove
it, as red as any carbon resistor flickering the guts of your rig with
surplus calories. You can recognize these veiled offerings of proof
of there being no way a transmitter suffers from reflected power in
that they talk about everything but the obvious inferno. Having that
larger surface area or mass also presents a problem though. It also
comes with a larger distance from any way to sink the heat except
through IR radiation and very little heat conduction (a lot is left up
to forced convection). In this sense, the Thermal Resistance is huge,
and the consequent failure is found in plates that melt or grids that
sag through heat expansion to the point that they short out to other
internal elements. My buddy's amp got so hot that the solder
connections to the socket pins of the tube (not the socket connector
it plugged into) dripped to the chassis pan and opened the filament
path.

If you read the dialog across enough time, you will observe that such
discussion is avoided so that any particular scribbler does not leave
a trail of admission to a fine point of Thevenin's theorem.... I will
leave such mysteries of the inner circle to other threads. ;-)

This last is probably more your problem of obtaining a straight answer
than any other source.

73's
Richard Clark, KB7QHC

Praise The Lord!!

For the first time in several months Cecil and I agree on something!

Now the question becomes: "Am I thinking like Cecil or is Cecil thinking
like me?"

Or, "Are we both correct?" Or, "Are we both incorrect?"

Chicken and eggs come to mind :-)

Our Engineering degrees date to the 'olden days' and may now be out of
date!!!

But, anyway, WE AGREE !!!!!!!
:-) :-) :-)

Deacon Dave, W1MCE

W5DXP wrote:
Dave Shrader wrote:

How does the wrong load impedance comes into existence?
Is it not caused by the mismatch?


Yep, the mismatch causes reflected waves which, in turn, cause the wrong
load impedance. It's easy to see in the following thought experiment.

200W source---one second long 50 ohm lossless feedline-----open

The source will output 100V at 2A for two seconds from key down and
be perfectly happy. The "wrong" impedance arrives exactly with the
reflected wave after two seconds. The center of the steady-state SWR
circle is the "right" impedance and therefore will not exist after two
seconds.

Richard Clark wrote:
If you have three Watts reflected, it came from the transmitter and in
fact never left it, it simply turned to heat.

One more example of religious faith-based physics. The three watts of
reflected power that came from the transmitter and was rejected by the
load, never left the transmitter? This bears a distinct resemblance to
the virgin birth.
--
73, Cecil http://www.qsl.net/w5dxp



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Dilon Earl wrote:
So I can change my reflected power, or SWR by adjusting my Pi-net
output?

No, but if a transmitter is capable of being happy, you can make
it happen.
--
73, Cecil http://www.qsl.net/w5dxp



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