  A high power microwave system based on power combining and pulse compression
of conventional klystrons is introduced in this paper. This system mainly
consists of pulse modulator, power combiner, driving source of klystrons and
pulse compressor. A solid state induction modulator and pulse transformer were
used to drive two 50 MW S-band klystrons with pulse widths 4 {\mu}s in
parallel, after power combining and pulse compression, the tested peak power
had reached about 210 MW with pulse widths nearly 400 ns at 25 Hz, while the
experimental maximum output power was just limited by the power capacity of
loads. This type of high power microwave system has widely application prospect
in RF system of large scale particle accelerators, high power radar
transmitters and high level electromagnetic environment generators.
