Keithley 2303, Service Manual, Page: 28 / 104

Calibration 2-3
• Calibration must be performed in the sequence outlined in this manual, or an error will
occur.
• If an error occurs during calibration, the Model 2303 will generate an appropriate error
message. See Appendix B for more information.
WARNING The maximum common-mode voltage (voltage between LO and chassis
ground) is 22VDC. Exceeding this value may cause a breakdown in insu-
lation, creating a shock hazard.
Calibration cycle
Perform calibration at least once a year to ensure the unit meets or exceeds its specifications.
Recommended calibration equipment
Table 2-1 lists the recommended equipment for the calibration procedures. You can use
alternate equipment as long as that equipment has specifications at least four times better than
corresponding Model 2303 specifications. See also Resistor considerations for important tem-
perature coefficient information.
1. Full-range, 90-day, 23˚C ±5˚C accuracy specifications of ranges required for various measurement points.
2. Characterize resistor using 4-wire ohms function and 20
Ω
range of DMM before use.
3. Required only for Model 2303-PJ. Characterize resistor using 4-wire ohms function and 200
Ω
range of DMM
before use. See Resistor considerations for temperature coefficient.
4. Required only for Models 2303 and 2303B. Characterize resistor using 4-wire ohms function and 20k
Ω
range
of DMM before use. See Resistor considerations for temperature coefficient.
Resistor connections
When performing calibration, make connections to the test resistors as shown in Figure 2-1.
Be sure to connect the Model 2303 SENSE leads and DMM test leads as close to the resistor
body as possible.
Table 2-1
Recommended calibration equipment
Description Manufacturer/Model Specifications
Digital Multimeter Keithley 2001 DC Voltage
1
20V: ±22ppm
Resistance
1
20
Ω
: ±59ppm
200
Ω
: ±43ppm
20k
Ω
: ±36ppm
Precision Resistor 4
Ω
, 0.1%, 100W
2
Precision Resistor 30
Ω
, 0.1%, 50W
3
Precision Resistor 3k
Ω
, 0.1%, 0.125W
4
深圳德标仪器
135-1095-0799