wrote:

Ahhhhh, finally. The not unexpected descent into non-sequitors.

Much safer than actually thinking about questions which might cause
you to change your world view.

Actually, my Mother just died and her funeral is on Saturday - so angels
are on my mind at the moment. Please forgive my mental lapse. It may
happen to you someday.
--
73, Cecil http://www.qsl.net/w5dxp



-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

wrote:
Ahhhhh, finally. The not unexpected descent into non-sequitors.

Much safer than actually thinking about questions which might cause
you to change your world view.

Oh, and allow me to add: Like my EE prof at Texas A&M in the 50's, I
consider instantaneous power to be a completely useless concept, fully
appropriately related to how many angels can dance on the head of a pin.
After all, how much power can traverse a point in zero time?
Hint: energy per delta-t if t=0 is zero!

I will never forget my prof's words: "Instantaneous power is about as
useful as tits on a boar hog." But I have an open mind - please convince
me that you are more brilliant than the head of the EE department at
Texas A&M.
--
73, Cecil http://www.qsl.net/w5dxp



-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

"Tom Bruhns" wrote
"Reg Edwards" wrote
Magid has the most rigorous derivation of power and energy flow on
transmission lines,
==========================
The following short question is adressed to all contributors to this
newsgroup who feel impelled to bolster their lack of self-confidence by
dragging in the chapter and verse of their favourite worshipped authors
and
Gurus, most of whom nobody has ever heard of and highly unlikely ever to
get
their hands on.

How do you know that?
============================

Gee, Reg, since you took that out of context, it seems a bit unfair.
Roy wrote it, and after the comma was, "I've seen." I don't know it,
but I'm willing to take Roy at his word on the matter.
===========================

The question asked was -

"How do you know that Magid has the most rigorous derivation of . . . . . .
".

Of what the derivation was was of no consequence. It was a matter of
judgement of Magid's (or anybody else's) qualifications and authority. What
was the purpose of referring to somebody hardly anybody has ever heard of?
---
Reg.

Gee, Reg, if all references had to be by someone you've heard of, we'd
be pretty much restricted to Heaviside and Edwards.

The purpose was to let people know that there's a derivation which looks
to me to be rigorous and which comes to an interesting conclusion -- the
same conclusion I reached some time ago with my own analysis, in fact.

A valid analysis is a valid analysis regardless of who did it. But for
anyone who is interested, Magid taught at M.I.T. and Brooklyn
Polytechnic Institute. In the introduction, the author states:

"I wish to express my profound indebtedness and thanks to Professors
Richard B. Adler, Lan Jen Chu, and Robert M. Fano of the Electrical
Engineering Department of M.I.T., both for their continued support and
encouragement in this project and for their and their present
publisher's (The M.I.T. Press) permission to draw freely on many of
their concepts, ideas, and even, in a few cases, some well-chosen words
from their abovementioned textbooks. I owe a special debt of gratitude
to Professor Chu for the innumerable hours that he unselfishly devoted
to assisting me in organizing this book."

I know this is meaningless to you, Reg, since you undoubtedly haven't
heard of any of those professors, either, let alone read any of their
classic papers. Perhaps you haven't heard of M.I.T., either, or at least
disdain it due to its location on the wrong side of the Atlantic. That's
fine. Thankfully, good engineering will continue to get done without
your approval. If you're interested only in analyses by people you've
heard of, that's fine. It's obviously a very short list, so you'll be
able to continue to reject just about anything out of hand.

Seeing something written certainly doesn't make it so. But seeing it in
a text that's undergone considerable scrutiny by very knowledgeable
people makes it worthy, to me, of careful consideration. Certainly it
deserves a lot more respect than off-hand comments from people with
little constructive or rational to offer. And certainly a lot more than
conclusions stated with great fan-fare and authority but not backed up
by any development or evidence.

Roy Lewallen, W7EL

Reg Edwards wrote:

The question asked was -

"How do you know that Magid has the most rigorous derivation of . . . . . .
".

Of what the derivation was was of no consequence. It was a matter of
judgement of Magid's (or anybody else's) qualifications and authority. What
was the purpose of referring to somebody hardly anybody has ever heard of?
---
Reg.

Roy Lewallen wrote in message ...
W5DXP wrote:
Roy Lewallen wrote:

p(t) = v(t) * i(t). Period. No phase, no vectors, no cross products.


Millions of power engineers have been taught that V*I*cos(theta) is power.
Are you disagreeing with that teaching?

Yes.

Yes, indeed. The power engineers who have to deal with electronic
power supply loads are quick to realize that sine waves aren't enough
for them. Things have changed in that regard since the 50's. It
became such a problem that there are now requirements for power factor
correction (or more accurately, for a maximum power factor, and
maximum harmonic content).

Cheers,
Tom

Y'all gotta r'call things are taught kinda differnt in Texas. I never
had a professor tell me that any concept was "useless as tits on a boar
hog", as Cecil's professor told him about instantaneous power. And that
admonition sure did stick with him, you might say like a fly on . . .

Roy Lewallen, W7EL

Tom Bruhns wrote:
Roy Lewallen wrote in message ...

W5DXP wrote:

Roy Lewallen wrote:


p(t) = v(t) * i(t). Period. No phase, no vectors, no cross products.


Millions of power engineers have been taught that V*I*cos(theta) is power.
Are you disagreeing with that teaching?

Yes.


Yes, indeed. The power engineers who have to deal with electronic
power supply loads are quick to realize that sine waves aren't enough
for them. Things have changed in that regard since the 50's. It
became such a problem that there are now requirements for power factor
correction (or more accurately, for a maximum power factor, and
maximum harmonic content).

Cheers,
Tom

Roy:

Isn't that "Stank on...."? Or did we live in different parts of Texas?
::grin::

73 de AI8W, Chris

Roy Lewallen wrote:

Y'all gotta r'call things are taught kinda differnt in Texas. I never
had a professor tell me that any concept was "useless as tits on a boar
hog", as Cecil's professor told him about instantaneous power. And that
admonition sure did stick with him, you might say like a fly on . . .

Roy Lewallen, W7EL

Tom Bruhns wrote:

Roy Lewallen wrote in message
...

W5DXP wrote:

Roy Lewallen wrote:


p(t) = v(t) * i(t). Period. No phase, no vectors, no cross products.



Millions of power engineers have been taught that V*I*cos(theta) is
power.
Are you disagreeing with that teaching?


Yes.



Yes, indeed. The power engineers who have to deal with electronic
power supply loads are quick to realize that sine waves aren't enough
for them. Things have changed in that regard since the 50's. It
became such a problem that there are now requirements for power factor
correction (or more accurately, for a maximum power factor, and
maximum harmonic content).

Cheers,
Tom

Roy Lewallen wrote:
Y'all gotta r'call things are taught kinda differnt in Texas. I never
had a professor tell me that any concept was "useless as tits on a boar
hog", as Cecil's professor told him about instantaneous power.

Back then, Texas A&M was an all-male military military college. We
just didn't have any spare time to spend on trivial subjects. :-)
--
73, Cecil http://www.qsl.net/w5dxp



-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

W5DXP wrote:

wrote:
Ahhhhh, finally. The not unexpected descent into non-sequitors.

Much safer than actually thinking about questions which might cause
you to change your world view.

Oh, and allow me to add: Like my EE prof at Texas A&M in the 50's, I
consider instantaneous power to be a completely useless concept, fully
appropriately related to how many angels can dance on the head of a pin.
After all, how much power can traverse a point in zero time?
Hint: energy per delta-t if t=0 is zero!

I will never forget my prof's words: "Instantaneous power is about as
useful as tits on a boar hog." But I have an open mind - please convince
me that you are more brilliant than the head of the EE department at
Texas A&M.

Are you sure you want to discard instantaneous power?

For consistency you will also have to discard:

instantaneous velocity - distance per time
instantaneous current - charge per time. It will be difficult to have
sine waves if the instantaneous current is always 0.
and inumerable other examples

And for consistency, you will also have to toss calculas, the art of
the infinitesimal, which will make solving most engineering problems
significantly more difficult, if not impossible.

Even your oft quoted expression, P = V * I * cos(theta), was derived
using calculus from the instantaneous P(t) = V(t) * I(t).

Are you sure you want to discard all thoughts of the instantaneous?

As to 'the head of the EE department at Texas A&M', he has either
been mis-interpreted or he is wrong. Not wishing to cast aspersions
on his brilliance, I suspect the former.

....Keith

|"Dr. Slick" wrote in message
| ...
| And strictly speaking:
| Reflection Coefficient = (Zl-Zo*)/(Zl-Zo)
| Where * indicates conjugate.
|...

Obviously by mistake.

pez
SV7BAX

Richard Clark wrote:
military military? Sounds like symptoms of testosterone poisoning.

Presently, it's just scrambled brains. But it was a long while until
I realized that A&M didn't stand for Atheletic and Military. :-)
--
73, Cecil, W5DXP

Cecil wrote:
"---A&M didn`t stand for Atheletic and Military."

The Agricultural & Mechanical College of Texas graduated more Army
officers than West Point. Although it was all-male until the Femanazis
prevailed, it had a chick ranch nearby until Marvin Zindler threw a
monkey wench in the works.

Best regards, Richard Harrison, KB5WZI

Richard Harrison wrote:
The Agricultural & Mechanical College of Texas graduated more Army
officers than West Point.

Gen. Patton once said something like: Give me a bunch of West Point Graduates
and I will win some battles. Give me a bunch of Texas Aggie Graduates
and I'll win the G-d damned war.

Although it was all-male until the Femanazis
prevailed, it had a chick ranch nearby until Marvin Zindler threw a
monkey wench in the works.

La Grange, TX, the Texas Aggie's favorite remote campuss.
--
73, Cecil, W5DXP

Dr Slick asked -
How could you get more power reflected
than what you put in?

======================

Quite simple! It's "Imaginary power".

As an experienced electrical engineer you should by now be familiar with
imaginary quantities. There's no need for confusion.

Mathematics can't be wrong. Only people can be wrong. Just carry on with the
calculations. If you asked a real sensible question then eventually you will
obtain a real sensible answer.
----
Reg, G4FGQ

Dear Reg & Group:
You are correct. The value found on the blackboard is wrong. I was
too hasty. When sitting down, the answer becomes clear. Perhaps at my
age my brain needs to be seated in order to work correctly.
You hypothesis on what we did wrong may well be on point. No way to
know.
Thank you also for your suggestions about the use of your computer
programs.

I apologize for being too hasty and not following the advice I
continually give my students: check your work.

73 Mac N8TT
--
J. Mc Laughlin - Michigan USA
Home:

"Reg Edwards" wrote in message
...
"J. McLaughlin" wrote -
Dear Reg:
Lab equipment was not used. The lab was just a convenient
gathering
place with a blackboard. (No cigarettes in our lab or anywhere
inside
buildings.)
I suspect that we made an arithmetic error. Need to revisit
what we
did - much too late at night right now.
Thanks for the poke. 73 Mac N8TT
===================================

Mac, you didn't make an arithmetical error. I think you used the wrong
value
of terminating reactance Xt. Just a Sherlock Holmes deduction. ;o)

The value of terminating reactance which gives greatest possible
magitutude
of reflection coefficient is equal to the magnitude of Zo which is
equal to
|Zo| = Sqrt( Sqr( Ro) + Sqr( Xo) ).

As you have already deduced, maximum value occurs when the angle of Zo
is
equal to -45 degrees at which Ro = -Xo.

You incorrectly set the terminating inductive reactance XL equal
to -Xo
whereas XL should have been Sqrt( 2 ) times greater.

Now if XL is incorrectly made -Xo then the reflection coefficient
calculates
to Sqrt( 5). Which is where your 5 comes from.

Somewhere in these threads I made the exactly same error myself in a
non-calculating context where it was not likely to be noticed. The
pair of
errors, yours and mine, were probably just coincidental.

I do hope I have not just introduced another. ;o)

You appear to be in an educational establishment. There are two
programs
available from the website below which you may find useful. Download
in a
few seconds and run immediately programs COAXPAIR and RJELINE3. They
have
been written according to classical transmission line formulae,
generally
accurate to all figures displayed and may be used to check other work
which
uses only engineering approximations. There are others also of
educational
value.
----
=======================
Regards from Reg, G4FGQ
For Free Radio Design Software
go to http://www.g4fgq.com
=======================