[Amps] Amplifuzz [TSPA]

[Tomm Aldridge]

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 at transmittersrus.com>
>> Subject: [Amps] Amplifuzz
>> To: amps at contesting.com
>> Message-ID: <$hsh1wRGjS+BFwKO at 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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