Keithley 2700, Service Manual

Page: 62 / 174

2-14 Calibration
Short and open calibration
1. Connect the Model 8610 low-thermal short to the instrument INPUT and SENSE termi-
nals as shown in
Figure 2-1 . Make sure the INPUTS button is not pressed in so that the
front inputs are active. Wait at least three minutes before proceeding to allow for ther-
mal equilibrium.
NOTE Be sure to connect the low-thermal short properly to the HI, LO, and SENSE termi-
nals. Keep drafts away from low-thermal connections to avoid thermal drift, which
could affect calibration accuracy.
2. Send the following command:
:CAL:PROT:DC:STEP1
3. After the Model 2700 completes this step, remove the low-thermal short, and then send
this command:
:CAL:PROT:DC:STEP2
NOTE Be sure to minimize movement near front Input terminals. Excessive movements can
cause capacitive coupling errors, which could affect calibration accuracy.
DC volts calibration
After the front panel short and open steps, do the following:
1. Connect the calibrator to the Model 2700 as shown in Figure 2-2 . Allow three minutes
for thermal equilibrium.
NOTE Although 4-wire connections are shown, the sense leads are connected and discon-
nected at various points in this procedure by turning calibrator external sense on or
off as appropriate. If your calibrator does not have provisions for turning external
sense on and off, disconnect the sense leads when external sensing is to be turned off,
and connect the sense leads when external sensing is to be turned on.