The Ludlum Model 500 Pulse Generator provides the functions necessary for use in calibrating Ludlum radiation detection instruments as well as many other scaler/ratemeter instruments from other manufacturers. The adjustable output pulse rate is displayed on a three-digit LED readout. Potentiometers (both coarse and fine controls) and a multiplier switch provide rates from 1 to 9.9 x 106 counts per minute (cpm). Pulse amplitude is controlled by a multiplier switch and a LO/HI potentiometer, while pulse polarity is chosen by a selector switch. Amplitude may be varied between 0 and a negative or positive 5 V, displayed on an analog meter. The high voltage of the instrument under test is displayed on an analog meter with markings of 0 to 2.5 kV.