The Trek Model 325 Electrostatic Voltmeter is a versatile instrument used for performing noncontacting electrostatic voltage measurements in applications which include contact potential (surface work function) determination, materials evaluation and electret studies. The Model 325 was specifically designed for high sensitivity applications to allow highly accurate, low noise, noncontacting measurement of electrostatic voltages of 0 to ±40 V over a wide range of probe-to-surface distances.
Special features of the Model 325 allow adjusting the performance of the unit to compensate for specific test conditions. A calibrated Null Voltage supply of 0 to ±10 volts nulls measured surface contact potential when measuring voltages on test surfaces. A response Speed Control adjusts the AC response of the Model 325. A Drift/Spacing Null Adjustment minimizes the variation in monitored voltage values as the probe to test surface spacing changes.
Trek’s patented low impedance probe sensor assures measurement accuracy which is essentially independent of probe-to-test-surface spacing while eliminating the external environmental effects of high humidity and contamination, such as airborne dust, toner, ions and chemicals, on measurement accuracy.
The Model 325 is bench top operable or, with optional hardware, in a half 9½-inch or standard 19-inch rack.
A dual range front panel 3½ digit LED display resolves ±10 mV. The measured voltage can also be monitored through a precision 1:1 voltage monitor output and/or a 10:1 voltage monitor output.
Measurement Range: 0 to ±40 V DC or Peak AC
Sensitivity: 1 mV
Noise: Less than 1 mV rms, Referenced to Measured Voltage
High Seed of Response: Less Than 3 ms for a 10 V Step
Voltage Monitor Accuracy: Better Than 0.05% of Full Scale
Null Voltage Source: 0 to ±10 Volt Calibrated Supply (nulls measured surface contact potential in reference to probe’s gold sensing electrode)
Drift Spacing/Null Adjustment (minimizes measured variations in voltage as probe to test surface spacing changes)
Voltage Monitor Outputs: 1:1 and 10:1 of measured voltage
Measurement Range: 0 to ±40 V DC or peak AC
Sensitivity：1mv
Accuracy
Voltage Monitor Output: Better than ±0.05% of full scale
Voltage Display: Better than or equal to ±2 counts,referred to the voltage monitor
Speed of Response (10% to 90%)
At Fastest Speed Setting: Less than 3 ms for a 10 V step
At Slowest Speed Setting: Less than 5 ms for a 10 V step
Noise (typical):Less than 1 mV rms,referenced to measured voltage
Stability
Drift with Time: Less than 50 ppm/hour,noncumulative
Drift with Temperature:
1:1 monitor output: Less than 50 ppm/°C
10:1 monitor output: Less than 100 ppm/°C
