Keithley 6487 Reference Manual

16-6 Calibration Model 6487 Reference Manual
Aborting calibration
You can abort the calibration procedure at any time by pressing the EXIT key.
Current calculations
When calibrating the 2nA-2μA current ranges, you must calculate the actual current val-
ues from the applied calibrator voltages and the characterized Model 5156 Calibration
Standard resistor values. Calibration currents are calculated as follows:
I = V/R
Where: I = required calibration current
V = calibrator voltage
R = actual standard resistor value
For example, assume you are calibrating the 20nA range using a 2V calibrator voltage
with an actual 100.5MΩ standard resistor value. The actual calibration current is:
2V/100.5MΩ = 19.9005nA.
Table 16-4
Calibration menu
Menu Item* Description
VOFFSET Performs offset voltage calibration.
COUNT Displays calibration count.
RUN Calibrates present current range.
VSRC-RUN Calibrates present voltage source range.
DATES Displays calibration and due dates.
UNLOCK Unlocks calibration using code.
LOCK Locks cal, exits to the main menu.
SAVE Saves calibration constants.
* Press MENU, select CAL, then press ENTER to access. Use up or
down RANGE key to scroll through selections.

Keithley 6487 Specifications

General

Type	Picoammeter/Voltage Source
Current Measurement Range	20 fA to 20 mA
Interfaces	GPIB, RS-232
Voltage Burden	< 200 µV
Input Impedance	>10^14 Ω
Power	100 V / 120 V / 220 V / 240 V
Basic Current Measurement Accuracy	0.4%