Keithley 237 High Voltage Source Measure Unit.  The photos are for illustrative purposes. We have 4 units in stock, so the actual unit you receive may be a different unit but they are all in very good condition and have been performance tested against an HP 3458A that was NIST calibrated and the Keithley source/meters were found to meet Keithley specifications and are guaranteed to pass NIST calibration. They are guaranteed to perform 100%. call Keith at 209-386-7544 with any questions. The Model 237 Source-Measure Unit (SMU) is a fully programmable instrument, capable of sourcing and measuring voltage or current simultaneously. This system is really four instruments in one: voltage source, current source, voltage measure, and current measure. The 237 sources voltage from 100μV to 1100V, and current from 100fA to 100mA. It can also measure voltage from 10μV to 110V and current from 10fA to 100mA. In the higher voltage range, current source and measure is 10mA maximum. It can be programmed to perform source-measurements as a function of a stepped voltage or current. Voltage and current can be swept linearly, logarithmically, or pulsed. The START, STOP, STEP method of setting sweep parameters allows operators to become proficient at using the instrument very quickly. Sweep parameters may be appended (APPEND key) to obtain more complex test sequences. Creating custom sweeps of voltage or current is facilitated by the use of three waveform operations: CREATE, APPEND, and MODIFY. These allow the user to select waveform parameters, combine multiple waveforms, and select and change any points in a waveform previously created or appended. The 237 outputs and inputs are fully guarded, and the units are configured to allow four-terminal measurements. Two-terminal measurements are also available for more standard test procedures. These outputs can be floated up to ±200V from ground.  Features:  Four instruments in one (voltage source, voltage measure, current source, current measure)  10fA, 10µV measurement sensitivity  1100V source and measure  Standard and custom sweep capability including pulse  1000 source/measurements per second  Four quadrant source operation  Internal 1000-reading memory  Voltage range maximum values: ±1.1 V, ±11 V, ±110 V, ±1100 V  Current range maximum values: ±1 nA, ±10 nA, ±100 nA, ±1 µA, ±10 µA, ±100 µA, ±1 mA, ±10 mA,