We measured the time and dose characteristics of electron and X-radiation of the иMA3-150З tube connected to the subnanosecond megavolt CпиH-2 accelerator. About ∼5×1012 electrons per pulse are generated when the accelerating-voltage pulse is ≥600 kV high and ≈=0.3 ns long. The current amplitude reaches ∼5 kA, and the radiation dose is ∼5 kGy/pulse. The X-ray dose from the external tantalum target is 0.15 Gy/pulse. The development of the electron-tube and X-ray-tube prototypes with considerably smaller sizes has opened up new fields of application in medicine and engineering.