Abstract : A high-power microwave (HPM) cross-calibration diagnostic package has been designed, constructed, and fielded on the DNA HPM source, Vircator I, at Physics International Company. The diagnostic was designed to measure HPM energy, peak power, pulse shape, frequency, and mode. The energy is measured with a homodyne detector with 350 ps rise-time response, time-resolved frequency is measured with a heterodyne detector, and mode measurements are obtained with a leaky-pipe radiator. The source operated and was diagnosed in the 8-12 GHz frequency range. Representative results are presented for 64 cross-calibration shots.