We have operated a high-current relativistic klystron (5 kA, 500 kV) at a repetition rate of 200 Hz for 200 shots in a single burst. The modulated beam current was approximately 80% of the DC current. With 60 ns duration electrical pulses, the microwave pulses at 1.3 GHz were of 50 ns duration. The peak power during a pulse was 150 MW; the average power during the burst was 1.5 kW. We anticipate reaching 1 GW peak power and 9 kW average power with improvements to the extraction cavity.