This report summarizes the present state-of-the-art achievements of GaAs FET transistors, assesses their probable capabilities and the associated technology problems. Designs of FET high power amplifiers are included and it is noted that measured intermodulation distortion in these amplifiers is higher than anticipated. Finally it is shown that efficient high power GaAs Read diodes of the hard punch-on variety can satisfy the TWTA distortion specifications. Thus an FET/Read diode hybrid amplifier is proposed that should meet all specifications except that of overall efficiency which would probably be reduced to 20-25%.