Richard,

This has been an entertaining monologue on electron tubes. (Must be
International Fractured Physics Week on RRAA.)

I won't attempt to address the numerous howlers, since Henry seemed
satisfied with your tale, but you might want to rethink the item you
"correct" in this message.

Secondary electron emission also occurs at much lower incident electron
energies. As a metrologist you are most likely familiar with electron
microscopy. Secondary electron emission is the typical mode of detector
operation. The incident electron energy in modern SEM's is now in the
range of 500 to 700 volts.

One of the reasons for adding more grids in vacuum tubes is to manage
secondary emission from the plate. This occurs at much less than 17 kV.

73,
Gene
W4SZ



Richard Clark wrote:
On Tue, 07 Jun 2005 11:44:29 -0700, Richard Clark
wrote:


When that electron stream strikes the plate and raises the
temperature, it is just short enough power to present this secondary
emission. But if we were to run at 17KV or so, then the electron
stream would be so aggressive as to produce high energy effects such
as X-Ray emission.


Something felt wrong here. I should have said:
...just short enough energy to present this secondary emission.

On Tue, 07 Jun 2005 20:17:28 GMT, Gene Fuller
wrote:

One of the reasons for adding more grids in vacuum tubes is to manage
secondary emission from the plate. This occurs at much less than 17 kV.

Hi Gene,

Sure, but not X-Rays which attend Cold Cathode tubes (skipping the gas
filled tubes I've already touched upon) and do require elevated
potentials to be so useful (that they become dangerously useful).

Glad you won't attempt the other howlers.

73's
Richard Clark, KB7QHC

Cecil Moore wrote:

Roy Lewallen wrote:

Finally, an actual answer. So of the 18 watts of "reverse power",
11.52 watts is making it to the source to "engage in constructive
interference". Does any of it get dissipated in the source resistor,
or does it just slide through unscathed?


It never encounters the source resistor as it is re-reflected by
wave cancellation, not by an impedance discontinuity. I have a QEX
article coming soon that will explain the details.

The Journal of Irreproducible Results could also be persuaded to publish
that claim, Cecil. Any implication that almost half of Maxwell's
equations are superfluous should easily qualify as an irreproducible
result. :-)

ac6xg

Give me a break, Reg. Download it for free and enjoy from:

http://www.sss-mag.com/pdf/hpan95-1.pdf

In all likelihood they won't be able to make any sense out of it
anyway.

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

I gave you a break. The whole lot of it is nothing but Scattering
parameters. Might be fine for SHF and above. Useless for mobile
matching at HF. As predicted I couldn't understand one line of it. I
doubt if anybody except the several authors have ever worked right
through it. Have you? (2 smileys).

It's mid-day here. There's not a drop of wine in the house.
----
Your old pal, Reg.

Reg Edwards wrote:

Give me a break, Reg. Download it for free and enjoy from:

http://www.sss-mag.com/pdf/hpan95-1.pdf

In all likelihood they won't be able to make any sense out of it
anyway.

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

I gave you a break. The whole lot of it is nothing but Scattering
parameters. Might be fine for SHF and above. Useless for mobile
matching at HF.

"Useless" only in the sense of being unnecessarily complicated and
inconvenient to use. But not incorrect!

ALL valid methods will give the same correct result, if they are applied
correctly. That's how we confirm that a method is valid - by checking
its results for a series of test problems that can be solved by other
methods too.

Roy has posed a test problem that is very easy to understand, and can be
solved unambiguously by simple arithmetic. Solving it using S-parameters
will take time and some depth of understanding, but we can be confident
that they WILL give exactly the same result in the end.

The challenge for Cecil is to make his own theory do the same.


--
73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

Cecil Moore wrote:

Jim Kelley wrote:

Cecil Moore wrote:

It can easily be shown that 300 joules of energy have been
generated that have not been delivered to the load, i.e.
those 300 joules of energy are stored in the feedline.


Not easy if t 2 sec. :-)


Of course, my statement is related to steady-state. I don't
see anything worth responding to, Jim. Where's the beef?

The problem is that there should only be a 1 second lapse of time
between the beginning of gozinta at 100 Joules/sec and the beginning of
comezouta at 100 Joules/sec. At what point is the additional 2 seconds
worth of energy fed into the system?

73, AC6XG

Jim Kelley wrote:

Cecil Moore wrote:
It never encounters the source resistor as it is re-reflected by
wave cancellation, not by an impedance discontinuity. I have a QEX
article coming soon that will explain the details.

The Journal of Irreproducible Results could also be persuaded to publish
that claim, Cecil. Any implication that almost half of Maxwell's
equations are superfluous should easily qualify as an irreproducible
result. :-)

Don't know exactly what you are inferring but the editors of QEX
have seen the light, :-) even if at RF frequencies. Quite a few
sources from the field of optics indicate that the phenomenon is well
known in that field even if not well understood in the field of RF.

It is very simple physics, Jim. When two coherent EM waves of equal
amplitudes and opposite phases attempt to travel in the same direction
in the same path, they cancel each other in their original direction
of travel. This is explained under "total destructive interference"
in "Optics" by Hecht. Since the energy in the two waves cannot be
canceled, that energy goes somewhere else. In a transmission line,
there are only two directions. If two waves cancel in one direction,
their combined energy components head back in the only other direction.
Everyone has seen that light interference pattern with his/her own eyes
and some just never realized what was happening.

Here's an example. If you wade through it, you will be forced to admit
that the destructive interference/wave cancellation at the non-glare
surface 'A' causes a reversal in the direction of the reflected
irradiance. That, my friend, is a 100% re-reflection, just as Walter
Maxwell has been saying for decades. 'n' is the index of refraction:

n=1.0 | n=1.2222 | n=1.4938
Laser-------air-------|---1/4WL thin film---|---infinite glass----...
| |
A B

The reflection from surface 'A' is canceled by an equal magnitude
and opposite phase reflection from surface 'B'. The energy components
in those two canceled waves join the forward wave because energy
cannot be destroyed (even though that concept seems to have serious
consequences to your mental health :-). Here's a quote from the
following web page.

http://micro.magnet.fsu.edu/primer/j...ons/index.html

“When two waves of equal amplitude and wavelength that are 180-degrees
out of phase with each other meet, they are not actually annihilated.
All of the photon energy present in these waves must somehow be
recovered or redistributed in a new direction, according to the law of
energy conservation ... Instead, upon meeting, the photons are
redistributed to regions that permit constructive interference, so the
effect should be considered as a redistribution of light waves and
photon energy rather than the spontaneous construction or destruction
of light.”

In an RF transmission line, since there are only two possible
directions, the only “regions that permit constructive interference”
and "redistribution in a new direction" at an impedance discontinuity
is the opposite direction from the direction of destructive
interference/wave cancellation.

The above laser example is virtually identical to the following:

RF XMTR--50 ohm coax--+--1/4WL 61 ohm coax--+--infinite 75 ohm coax

If we use a coherent laser beam, no coax is required, so the
behavior of the actual EM waves is relatively easy to analyze.
--
73, Cecil http://www.qsl.net/w5dxp

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Reg Edwards wrote:
I gave you a break. The whole lot of it is nothing but Scattering
parameters.

Exactly. There's nothing better for analyzing a transmission
line discontinuity. And there's nothing better for understanding
reflections.

It's mid-day here. There's not a drop of wine in the house.

Have some wine and you'll be able to understand the HP Ap Note.
That's how I first understood it. :-)
--
73, Cecil http://www.qsl.net/w5dxp

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Ian White GM3SEK wrote:
Roy has posed a test problem that is very easy to understand, and can be
solved unambiguously by simple arithmetic. Solving it using S-parameters
will take time and some depth of understanding, but we can be confident
that they WILL give exactly the same result in the end.

It's not Roy's results that are flawed. It's his premises. If
one has a 100v source with a 50 ohm series impedance feeding
a 200 ohm resistor, Roy's results are perfect. But when we add
that 1/2WL of 200 ohm line, it changes things from a circuit
analysis to a distributed network analysis. Much more energy
is stored in the system, using the transmission line, than has
reached the load during steady-state. Roy tries to completely
ignore the stored energy and alleges that there is no energy in
the reflected waves. But there is *exactly* the same amount of
energy stored in the feedline as is required for the forward
waves and reflected waves to posssess the energy predicted by
the classical wave reflection model or an S-parameter analysis
or an analysis by Walter Maxwell of "Reflections" fame.

The challenge for Cecil is to make his own theory do the same.

"My theory" gives the exact same results as an S-parameter analysis
or a classical wave reflection model analysis. That's why I know it's
correct. Roy's (and Dr. Best's) models give the correct results for
voltage and current but not for power/energy. Remember Dr. Best's
assertion that 75w + 8.33w = 133.33w? It's been four years since
I told him here on this newsgroup that was ridiculous and that
75w + 8.33w + 50w of constructive interference = 133.33w
He responded that no interference existed or was necessary. That
can be verified by accessing Google, summer 2001.

Interference is built into the S-parameter model and the classical
wave reflection model but a lot of RF people don't recognize it. Dr.
Best's term, 2*SQRT(P1)*SQRT(P2), is known in the field of optics as
the "interference term" but he didn't know that at the time of
publication of his QEX article.
--
73, Cecil http://www.qsl.net/w5dxp

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Cecil Moore wrote:

Jim Kelley wrote:
The Journal of Irreproducible Results could also be persuaded to
publish that claim, Cecil. Any implication that almost half of
Maxwell's equations are superfluous should easily qualify as an
irreproducible result. :-)


Don't know exactly what you are inferring but the editors of QEX
have seen the light, :-) even if at RF frequencies. Quite a few
sources from the field of optics indicate that the phenomenon is well
known in that field even if not well understood in the field of RF.

Cecil,

The Journal of Irreproducable Results is a hilarious journal that has
had a number of interesting articles in it. One I remember had to do
with Peanut Butter and the Three Stooges and the Precession of the
Earth's Axis (someone correct me if I misremembered). I believe it has
been referred to as Mad Magazine for Stephen Hawking.

Another had to do with a nice compression algorithm that eventually
reduced the input to 1 bit, no matter the input, and since that bit was
predictable as just a 1, we could eliminate that also.

tom
K0TAR