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Old June 18th 08, 10:16 PM posted to rec.radio.amateur.antenna
Walter Maxwell Walter Maxwell is offline
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First recorded activity by RadioBanter: Jul 2006
Posts: 233
Default Efficiency and maximum power transfer


"Richard Clark" wrote in message
...
On Wed, 18 Jun 2008 11:59:40 -0400, "Walter Maxwell"
wrote:

Hi Richard C,

Am I hearing you correctly? Are you disagreeing with Richard H? Are you

saying
that maximum power transfer, conjugate match at the output, and Z match

cannot
occur simultaneously?


Hi Walt,

For a Class C tube amplifier.

All descriptions of tune-up for a Class C tube amplifier describe a
qualitative MPT as this classic method offers absolutely no
information about the quantitative degree of initial mismatch, nor
subsequent proximate match. In other words, there are no quantitative
values of load impedance revealed by this method. It may even be said
that the classic tune-up only describes "an attempt" at MPT; as it
may, in fact, not even achieve anything more than Mediocre Power
Transfer. After peaking the grid and dipping the plate, I have
observed many different peaks and dips for many various loads to know
that not all loads obtained all available power.

The classic description of a tune-up is based on qualitative
assumptions and the amplifier is brought into its best attempt, which
is not demonstrably efficient, nor even proven to be "matched"
conjugately or by impedance. This takes more information (so far
unrevealed) obtained by current into the known load (unrevealed), and
power into the source (unrevealed). No one other than myself has
expressed the loss of the source because no one else has ever
enumerated its resistance (a topic commonly hedged and avoided) Hence
discussion of efficiency is lost in the woods and correlation to
MPT/Z/Conjugation is equally doomed to ambiguity.

Are you serious? As I understand Everitt's statement of


Everitt notwithstanding, Lord Kelvin trumps him with
"when you cannot express it in numbers, your knowledge is of a
meagre and unsatisfactory kind"
This thread has suffered from a lack of measurables that are not that
difficult to obtain.


Richard, are you inferring that I have not submitted the measurables required to
determine the source impedances of the xmtrs I measured? What additional
measureables that I haven't already submitted are you asking for to prove the
source impedances that I've already submitted are valid?

So, to return to my very specific question:
What is the source resistance of any power amplifier?


Richard, the source impedance of one of the xmtrs I measured with load impedance
of 17.98 + j8.77 ohms measured 18 - j8 ohms. Considering measurement error,
wouldn't you agree that these two impedances qualify for a conjugate match, and
that this value of source impedance is valid at least within the realm of
possibility?

For any match?

One complex number is sufficient, and certainly that value will
resolve all imponderabilities is what I am asking for.


OK, Richard, is impedance 18 - j8 ohms sufficient?

Richard Clark, KB7QHC


Walt,W2DU