It is actually the NPWM group, not teh Phasex group. I stand corrected.
John T. M. Lyles wrote:
I agree with Philip, I could not find it either on Yahoo groups.
Ampliphase, the RCA tradename for outphasing modulation, goes back to
the classic paper by French engineer H. Chireix in Proc of the IRE, Vol.
23, p 1370-1392, dated Nov. 1935. Gaudernack reported on his phase
opposition system for AM in Proc. IEEE in Aug, 1938. As far as i know,
only Marconi and RCA have built successful high power broadcast
transmitters with it, and the New Zealand company Blyth attempted to
market solid state MW models about 5 years ago, but pulled it back and
converted to conventional PWM, class D. There has been a lot more
interest in Outphasing modulation with the advent of personal wireless
communications with long battery life. D. C. Cox revised the technology
when he wrote his paper on LINC, Linear Amplification with Nonlinear
Components, in IEEE Trans. Communications, Vol. com-22, p. 1942-1945 in
December 1974.
A recent general reference is Fritz Raab's "Efficiency of Outphasing RF
power Amplifier Systems", IEEE Trans. Communications Vol. com-33, #10,
p. 1094-1099, Oct. 1985. Also, its in his book with the late Herb Krauss
of Virginia Tech, Solid State Radio Engineering. (I was in the first
classes under Dr. Krauss to use this textbook in college).
Of interest to the microwave designers is the reuse of the wasted power
(as both amplifiers are running full carrier, and when outphased, the RF
usually goes into a combining system/load). For instance, R. Landgridge,
A Power Re-Use Technique for Improved Efficiency of Outphasing Microwave
Power Amplifiers, IEEE Trans. MTT, Vol 47, #8, p. 1467-1470, Aug. 1999.
Getting two RF amplifiers to be able to operate at high efficiency while
driving reactive loads (when they are summed without a hybrid combiner)
during modulation has been one of the problems of this technology. Doing
this in a frequency agile way is even more challenging. According to
Raab, the resulting efficiency has been likened to class B with all
practical aspects such as this. Except that the fidelity of an
outphaser is better without the iron transformers in the audio. A good
summary report describing most of the high efficiency RF power amplifier
configurations was in High Frequency Electronics magazine, in a series
of articles, Msy 2003. Should be available online for download.
Five years ago I built a great phase shifter that would swing the RF
phase of a 1 - 10 MHz signal by many degrees(360) at an audio rate,
extremely linear, using the now obsolete Analog Devices AD639
trigonometry chips in a DSB modulator scheme. This was going to be the
front end of an outphasing AM rig made with two nonlinear MOSFET
amplifiers, but I since gave it up to concentrate on PDM/PWM modulator
with class D rf.
I look forward to hearing about what the PhaseX group comes up with.
73
John
K5PRO
Message: 1
Date: Thu, 27 Jan 2005 17:45:42 +0000
From: Philip de Cadenet <phil@transmittersrus.com>
Subject: [Amps] Amplifuzz
To: amps@contesting.com
Message-ID: <$hsh1wRGjS+BFwKO@philstheboss.freeserve.co.uk>
Content-Type: text/plain;charset=us-ascii;format=flowed
Skipp,
I searched PhaseX on Yahoo Groups and it came up zilch.
Can you post the group URL?
Tnx
--
Philip de Cadenet G4ZOW
Transmitters 'R' Us
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