A sampling oscilloscope is described with a 10 to 90% rise time of 5.6×10−10sec. Maximum useful sweep speed is about 10−10sec/in.; maximum useful sensitivity about 15 mv/in. These are limited solely by the peak time jitter of 2×10−11sec, and apparent input peak noise of about 300 &mgr;v. Unlike prior sampling devices, pulses of constant or random repetition rate are displayed with equal facility. The usual time jitter associated with the display of random pulse heights is eliminated by selecting for display only those pulses that fall within a kicksorter channel. The average wave form of pulses with moderately irregular shapes is particularly easy to measure.