[AMPS] Re: conjugate match

[Jim Reid]

At 09:47 AM 3/9/97 -0500, Tom Rauch (W8JI) wrote:
A lot of snips,  then:

>A conjugate match is when the source appears as the complex conjugate of
>the load presented at the generator's output port. The complex conjugate
>is the same resistive part, and the opposite reactance sign and but same
>amount.

Comment:  If a transmission line is operating in a conjugate matched
system,  cut the line anywhere:  measure the impedance looking forward,
then in the back directions.  The real part,  the resistance,  will be
measured as the same in each direction; the reactive parts will be
equal in magnitude,  but of opposite polarities.

The ARRL Antenna Books for many editions now have all
carried Walt Maxwell's, W2DU, work and words about conjugate matching 
and antenna tuners (transmatches).  I am not aware that the ARRL
now is doubting Walt's work.  If so,  it is because of measurments
by Walter Bruene, W5OLY. See his article,  "RF Power Amplifiers and the
Conjugate Match", QST,  Nov. 1991,  pg. 31 and following.  Also see 
Bruene's article, Technical Correspondence, QST, May 1992, pg. 95

snip ,again

> tube is a resistance that varies with time. It can NOT source
>anything, it only acts like a variable resistor.
 
>The tank is an "impedance" that is effectively in series with the power
>source and the tube resistance.

snip agaon:

>The effect of reflected waves STOPS at the tank circuit (everything past
>the tank is a linear constant impedance because the tank is a "flywheel"
>or energy smoothing system).

>Applying reflected power PAST the tank or output harmonic filter (in a
>solid state PA) is totally incorrect. When Mr. Thevenin wrote his
>theorum he plainly said so. Somehow the handbooks have forgotten to read
>the text of the rules they quote.
>
>So reflected power does NOT go back to the tube. 

snip again:

>Circuit theory works for both the transmission line, and at the tube.
>Conjugate matching only works in the case of a non-time varying
>impedance, or from the tank OUT to the antenna. 
>

Tom's words are well written;  would be great to have both Walt
Maxwell and Walter Bruene read his piece,  then comment about
it and their own disagreements about this topic going on now
for several years!  Maxwell's book, "Reflections", stands on
it's own merit.  There are few technical books that I find
difficult to put down,  but his,  I nearly read cover to cover
when I first discovered it.  Talk about overturning Old Ham
Tales!!  Walter Bruene, on the other hand,  wrote all of
Chapter 14, "High-Power Linear Amplifiers", over 30 pages long,
in the excellent text, "Single Sideband Principles and
Circuits",  edited by Sabin and Schoenike, published by
McGraw Hill,  1987.  22 authors within this excellent
book, all by Collins Radio and Rockwell men.  Many of these
men, along with Art Collins of course, are the Fathers of our 
amateur SSB technology.

I have enjoyed the priviledge of personal correspondence with
both of these men about this topic,  transmatches,  conjugate
circuits and just chat.  Also with others who felt Bruene to
be not quite correct.  Many have attempted to get the ARRL
to publish clarifying views to what Bruene has published.  To
my knowledge none has been printed (One piece in particular
I got to read was by John Belrose, VE2CV.  He wrote a commendable
article on this topic with specific technical refutation of
Walter Bruene's QST article.  He had believed,  based upon
apparent ARRL editor feedback,  that his well done piece
would be published in a 1993 QST Technical Correspondence column.
Evidently never appeard,  a pity.

Based upon Tom's submission to this reflector,  I believe
we should all be willing to reconsider and review what we
always believed was so.  Maybe it was not quite so nearly
so.

73,  Jim,  KH7M
On the Garden Island of Kauai








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