An initial experiment is underway to utilize the virtual-cathode-driven oscillator as a source of high-power microwave on a Flash-II accelerator. The most recent experiment launches 113 J per pulse, with frequency in the band around 9 GHz. The highest power, about 4.5 GW in a short burst, was obtained using axial extraction (in a TM radiation pattern) without applied magnetic field. The simple E-probes are applied to pick up the microwave signal inside a circular waveguide of 29.2 cm inner diameter. The microwave signal was power-divided to provide a time fiducial with the rest of the signal which was transmitted through a 61.5-meter BJ100 X-band dispersive delay line, both signals were then fed to an oscilloscope to provide a time-dispersed frequency spectrum. A 24.2 cm long conical titanium calorimeter was attached to the axial opening to measure microwave energy.