ABSTRACTPulsed X-band (8.2 - 12.4 GHz) IMPATT oscillators have been fabricated and characterized. They utilized 4H-SiC diodes with single drift p+-n-n+ structures and avalanche breakdown voltages of about 290 V. The microwave oscillations appeared at a threshold current of 0.3 A. The maximum measured output power was about 300 mW at input pulse current of 0.35 A and pulse duration of 40 ns.