Unlike their tube counterparts, high power solid state amplifiers are a rare challenge met by hams.  Mistakes can be costly--RF transistors are much faster than fuses.  But, here are a few examples of homebrew designs.

Solid State 600W Output Amplifier
using four Motorola MRF 150 FETs by Tom Sowden W6KAN/K0GKD.

An Experimental Solid-State Kilowatt Linear Amplifier for 2 to 54 MHz 
QST September 1992, pp. 19-23
This is not a step-by-step construction article, but a springboard from which to build a 35-pound kilowatt solid-state amplifier.

A Compact 1-kW 2-50 MHz Solid-State Amplifier  
QEX July 1990, pp. 3-8