An experimental investigation of a relativistic Magnetron with Diffraction Output (MDO) on a short voltage pulse generator, which has maximum repetition rate of 100 Hz and plateau of 2.5 ns, is detailed in this paper. Compared to the conversional solid cathode, a direct Density Modulation Cathode is capable for desired microwave radiation. When applied voltage is 200 kV and axial magnetic field is ∼0.12 T, the MDO radiates 120 MW of microwave with 2.3 GHz of central frequency. Power conversion efficiency reaches 22%. Pulse duration is 3 ns. At repetition rates of 50 Hz and 100 Hz, output microwave powers range from 90 MW to 120 MW. Life time is up to 104 shots.