"Claude Frantz" wrote in message
...
Where can I find good information about the principle and the design of
linear power amplifier using semiconductors, up to the full legal
power limit ?

Is it only possible to use power splitter ? I have seen broadcast
transmitters in the power range of many hundred of kW's, having an
power efficiency of more than 90 %. Do they use power splitter or
another design ?

First, you should have references to Helge Granberg (sk) work when he worked
at Motorola.
His work can be found in several Application Notes and a book he wrote with
Norman Dye.

RF Transistors (about 1/2 down this web page)
http://www.rfparts.com/tranbook.html

Motorola Application Notes (this is a subset on CCI web site)
http://www.communication-concepts.co...tion_notes.htm

JA0TJU is an excellent resource and reference for "broadcast style"
construction
http://www.ginzado.ne.jp/~hamradio/tju/2c3286.htm

DL4MUP has this article (may not load), he references the earlier work of
W9NUP
http://www.qsl.net/dl4mup/UKW45/UKW45_w.pdf

W9NUP, Ron Purkey article in Issue 3 of the 1999 VHF Communications magazine
on "Another RF Combiner / Splitter".

He built a 1 KW VHF amplifier using 4 MRF 141G modules with a splitter and
combiner running 28v @ 60+ amps.
The amp takes approx 50 watts to drive.

This was NOT the normal "rat race" type of combining, but rather based on
Myat Engineering E*Star (which is a European firm).
Any number of odd or even modules may be employed, making it nice for
growing as can be afforded.

I understand Myat took down their informational Internet web site after this
article appeared (too many hits and questions)

Here are pictures from the K5OE web site
http://members.aol.com/homebrewpics/w9nup_front.jpg

the rear
http://members.aol.com/homebrewpics/w9nup_rear.jpg

the bottom
http://members.aol.com/homebrewpics/w9nup_bottom.jpg

and the top
http://members.aol.com/homebrewpics/w9nup_top.jpg