Keithley 2750, Service Manual

Page: 53 / 179

Model 2750 Multimeter/Switch System Service Manual Calibration 2-5
Mod
el 27
50 Cal
ibr
ation
Comprehensive calibration
The comprehensive calibration procedure calibrates the DCV, DCI, ACV, ACI, and ohms
functions. You can also choose to calibrate only the DCV/DCI and resistance or ACV/ACI
functions.
These procedures are usually the only calibration required in the field. Manufacturing cal-
ibration is normally done only at the factory, but it should also be done in the field if the
unit has been repaired. See “
Manufacturing calibration ” at the end of this section for more
information.
Calibration cycle
Perform comprehensive calibration at least once a year, or every 90 days to ensure the unit
meets the corresponding specifications.
Recommended equipment
Table 2-1 lists the recommended equipment you need for comprehensive, DC-only, and
AC-only calibration procedures. You can use alternate equipment, such as a DC transfer
standard and characterized resistors, as long as the equipment has specifications at least as
good as those listed in the table. In general, equipment uncertainty should be at least four
times better than corresponding Model 2750 specifications.
Table 2-1
Recommended equipment for comprehensive calibration
Fluke 5700A Calibrator:
DC Voltage
AC Voltage
(1kHz, 50kHz)* DC Current
AC Current
(1kHz) Resistance
10V: ±5ppm
100V: ±7ppm
10mV: ±710ppm
100mV: ±200ppm
1V: ±82ppm
10V: ±82ppm
100V: ±90ppm
700V: ±85ppm
10mA: ±60ppm
100mA: ±70ppm
1A: ±110ppm
100mA: ±190ppm
1A: ±690ppm
2A: ±670ppm
100

: ±17ppm
10k

: ±11ppm
100k

: ±13ppm
1M

: ±18ppm
Miscellaneous Equipment:
Keithley 8610 low-thermal shorting plug.
Double banana plug to double banana plug shielded cable.
BNC to double banana plug shielded cable.
* 1kHz specifications. 10mV and 700V points require 1kHz only. All calibrator specifications are 90-day, 23°C ±5°C specifications
and indicate total absolute uncertainty at specified output.