A message sent to the SoftRock40 news group led to an interesting discovery. There is an interesting 4-part series in the journal "High Frequency Electronics" that is a tutorial on various techniques to achieve high efficiency power amplifiers. The article mentions the Doherty technique from the 1930's which was the progenitor of Meinzer's HELAPS. To fetch the series, surf to http://www.rfcafe.com/references/magazine_articles/magazine_articles_2003.ht... which leads to the 4-part article "RF & Microwave Power Amplifier & Transmitter Technologies".

73, Tom