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



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