GENERAL The Keithley Model 240A is a compact high voltage supply which provides accurate, stable outputs from 0 to 1200 volts dc. Accuracy is +1% of the dial setting for all outputs. Stability is +0.02% +2 millivolts the first hour or in subsequent 8-hour periods, after a 30-minute warm-up. Line regulation is +0.005% +2 millivolts for a 10% change in line voltage, and load regulation is +0-0057o +2 millivolts from no load to full load. FEATURES. a. Three Digit Resolution. Three in-line calibrated dials set the output voltage in 1-volt steps. A TRIM Control permits interpolation between steps with better than 5-millivolt resolution. Output can be selected positive or negative with respect to ground. b. Overload Protection. Repeated overloading or operation in an overloaded condition for long periods will not damage the Model 240A. Overload protection limits the output current to less than 13 milliamperes and, when the overload is removed, automatically returns the Supply to its set value. c. Solid-State Design. The circuit for the Model 240A takes advantage of the reliability and stability of a solid-state comparator amplifier, and the high voltage capability of a series regulator tube to provide a high performance circuit.