"Lossless resistance?" Would that be zero resistance,
or perhaps a negative resistance, as in the active part of
a tunnel diode's V-I characteristic?

I am a career EE, with a couple of graduate EE degrees;
and this is something entirely new to me. Could you explain
this concept, and/or provide some references?

Thanks, Ed

What he is analyzing is not directly applicable to an RF amplifier. He is
looking at the whole thing, power source and generator. An RF analogy would
be a poorly regulated DC supply that is feeding an RF amplifier. Reduce the
load, and the DC voltage goes up. This changes the RF output.

RF amps are not power limited, up to the point where the transistor melts.
They are voltage limited; you can not get a peak RF drain voltage (inside
the die) greater than the DC supply voltage. A secondary effect of a load
change is caused by the gain of the transistor being current and voltage
dependent.

Tam/WB2TT
"Dave" wrote in message
...
have you guys read this one yet?

www.qsl.net/w9dmk/MPTT.pdf

On Wed, 03 Mar 2004 00:56:57 GMT, "Old Ed"
wrote:

"Lossless resistance?" Would that be zero resistance,
or perhaps a negative resistance, as in the active part of
a tunnel diode's V-I characteristic?

I am a career EE, with a couple of graduate EE degrees;
and this is something entirely new to me. Could you explain
this concept, and/or provide some references?

Thanks, Ed

Hi Ed,

This is the most useless term employed in these threads; what I call a
difference without a distinction.

To put it shortly, it is the resistance observed in an infinite
transmission line (better known as the Characteristic Z) or the
resistance of an antenna (better known as the Radiation Resistance).
You will note that a competent engineer already understands the nature
of this resistance, shrubs may need more words to obtain the same
knowledge.

Some explanations like to force it into the same definition of Z, and
then add more words to denote there is not reactance, and then more
words to add there is no heat generated.

In other words (too many of them) the issue is driven from the physics
of heat which if anyone peeled back the onion layers, then they would
find they have not actually escaped from it all, and more words are
forced into the definition to argue what dissipation means.

Principally, a new instrument has been added to the Ohm Meter, the
thermometer, to prove you have in fact measured the value of a carbon
composition resistor. No one actually does this; no one actually
could offer a suitable caloric answer if their life depended on it;
and certainly no one could tell you what the resistance is from a
thermometer reading. But they would demand it is necessary none the
less. ;-)

73's
Richard Clark, KB7QHC

John Smith wrote:
Check for reflected power in either direction.
If none, then it is conjugally matched exactly.

Isn't a 50 ohm transmitter conjugately matched to a 50 ohm load
when fed through 1/2 wavelength of 450 ohm ladder-line?
--
73, Cecil http://www.qsl.net/w5dxp



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Gene Fuller wrote:
Are you suggesting that a steam engine is needed in addition to "obvious
and elementary notions"?

I didn't say anything about a steam engine, Gene. The question is:
How do you prove a conjugate match exists through measurements when
you are completely ignorant of the source impedance?
--
73, Cecil http://www.qsl.net/w5dxp



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Cecil,

8-) 8-) 8-)

8-) 8-) 8-)


(You seemed to miss the single smiley on my previous message, so I
though I would try a few more.)


The "proof" of something when one does not have adequate information is
often called "faith".


More to the point, there are several possible answers.

1. Who cares? If you can't measure it and you can't adjust it, just
forget about it. Lack of maximum power transfer is rarely fatal.

2. If you are operating an amateur radio station just twist the knobs on
the tuner until the transmitter is happy.

3. If you are designing a system to be sent into space then analyze and
test the heck out of it.

73,
Gene
W4SZ


Cecil Moore wrote:
Gene Fuller wrote:

Are you suggesting that a steam engine is needed in addition to
"obvious and elementary notions"?


I didn't say anything about a steam engine, Gene. The question is:
How do you prove a conjugate match exists through measurements when
you are completely ignorant of the source impedance?

Gene Fuller wrote:
(You seemed to miss the single smiley on my previous message, so I
though I would try a few more.)

Why do you use 8's in your smileys? That's why I missed it.
--
73, Cecil http://www.qsl.net/w5dxp



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"John Smith" wrote in message ...
From the design side, MPTT is defined at an interface, and minimizes
"reflected power" at that interface, and that is it.

The other items about matching are also quite important, such as stability,
loading, impedance transfer (both directions), bandwidth, Qs, loaded Qs etc.
But that is Not MPTT. There is a tradeoff between these, if one can also
obtain mptt, great, but close is good too.

mptt is just one of several parameters needed to optimize a match. At times
there are too many unknowns and the matching is experimental (class C)

Experimental ! Not any more, the computor does it quite easily
Regards
Art

When a candidate for an EE faculty position visits, someone, usually at
lunch, will bring the conversation around to the MPTT. If he or she
does anything other than giggle they do not get my vote.

Let us leave this tar-baby out in the field. 73 Mac N8TT

--
J. Mc Laughlin - Michigan USA

Why do you use 8's in your smileys? That's why I missed it.
--
73, Cecil http://www.qsl.net/w5dxp


They must be inteligent smileys, with glasses 8-)
or divers 0-) or rich ones $-)

BUm