A description is given of a pulse amplifier whose output voltage can be accurately controlled by the setting of a ten‐turn potentiometer. The output amplitude and pulse lengths are variable up to 1000 v, 2.6 amp, and 10 &mgr;sec, respectively. An accuracy of 2 v is achieved, independently of external conditions, by the use of strong negative feedback to compare the output with a reference dc voltage. The various sources of error are discussed.