Model 370DC-Stable Electrostatic Voltmeter The Trek Model 370 is a precision electrostatic voltmeter with the unique capability of making noncontacting surface voltage measurements in the range of 0 to ±3 kV DC or peak AC. The 370 employs an electrostatic field-nulling technique which achieves high dC stability and high measurement accuracy even if the probe to measured surface spacing changes. This permits measurements of either stationary or moving surfaces without the need to establish fixed spacing to maintain accuracy. An automatic gain control feature of the 370 eliminates the need for manual adjustment when changing probes or when changing the probe to measured surface separation. The 370 also features one-step, push-button zeroing. When the ZERO button on the front panel is pressed, the 370 automatically adjusts the output to zero volts when the probe is coupled to a known zero volt surface. A precision voltage monitor provides a low-voltage replica of the measured electrostatic voltage for external monitoring purposes, or for use as a feedback signal in a closed-loop system. An optional data acquisition module is available, featuring an IEEE-488 compatible interface, 14-bit resolution, 12-bit accuracy, and a programmable sampling period from 10 jus to 30 minutes. The 370 can be operated on a bench top or, with optional hardware, in a standard 19-inch rack. • Very High Speed of Response: Less than 50 ms for a 1 kV step • Measurement Range: 0 to ±3 kV DC or Peak AC • Measurement Accuracy: Better Than 0.05% of Full Scale • Automatic Gain Control (eliminates manual adjustment) • One Step, PushButton Zeroing • Precision Voltage Monitor Output • Optional Data Acquisition Module (with an IEEE-488 compatible interface) • (€ Compliant Measurement and Power Solutions™www.trekinc.com

Model 370 Specifications All specifications are with a 3800E-2 probe at a probe-to-surface separation of 2 mm unless otherwise noted. Performance Features (cont.) General Measurement Range 0 to ±3 kV DC or peak AC. Measurement Accuracy At the Voltage Monitor Better than ±0.05% of full scale. At the Voltage Display Better than ±0.1% of full scale ±1 count, referred to the voltage monitor. Speed of Response (10% to 90%) Less than 50 ms for a 1 kV step. Stability Drift with Time Less than 150 ppm/hour, noncumulative. Drift with Temperature Less than 100 ppm/°C. Probe-to-Surface Separation 2...