In the S-band Stanford linear accelerator center energy doublers (SLED) compression experiment, the SLED was measured in low power and high power, including its parameters, output power and power amplification. In the experiment, the microwave source system was modified and a synchronizing signal generator was developed. The influence of the input power width upon the output power and the RF breakdown in the experiment were also studied. When the input power was 5 MW, a power amplification of 7.122 at 260 ns and a peak power of 35.35 MW were acquired.