Keithley 642
Electrometer, 10aA - 200nA

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Product Overview

RENT KEITHLEY 642 Electrometer (call for availability)

The Keithley 642 unit is a direct-reading MOSFET-based electrometer for sensitive measurement of current, voltage, or charge.

Features and Specifications of the Keithley 642 Electrometer include: 

• 10^-17A (10aA) Sensitivity
• Over 100:000:1 linear dynamic range at analog output
• Fast Response: 22msec. time constant on 10^-10A range
• Current Measurement Range:  10aA - 200nA (with typ < 1mV voltage burden)
• Voltage Reading Capabilities: 10µV - 10Vb (with 10,000TO input resistance)
• Charge can be measured from 800aC -100pC
• Maximum sensitivity is obtained when using the CHARGE mode to integrate current applied to the input
• High Resolution:
• Digital format allows observation of small changes in large signals with resolution to 1 part in 20,000 at digital display
• Feedback output has low noise and non-linearity (= 5ppm)
• Wide dynamic range provides constant gain over the full span and eliminates the need for range changing
• State-of-the-Art Design:
• Uses specially packaged dual monolithic MOSFET with compensated temperature coefficient in a guarded package
• Design of remote head minimizes the active input volume
• Remote head is sealed and contains desiccant paper to maintain low internal humidity
• Preamplifier is a direct-coupled circuit with a single, well-controlled time constant
• ZERO CHECK switching mechanism allows for minimum charge transfer (typ < 10fC)
• Three Analog Outputs:
• FEEDBACK output on the remote head has:
• most precision
• widest dynamic range (over 10⁵)
• lowest noise
• fastest speed
• 1V / 10,000 COUNTS output on the rear panel normalizes the output to 1V per 10,000 counts regardless of range
• 1V / 100 COUNTS output the rear panel is useful in sensitive measurements to amplify the signal so that 1V corresponds to 100 counts

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