Keithley 7708 User Manual page 20

Verifying resistance
Check resistance by connecting accurate resistance values to the Model 7708 and verifying that its resistance readings are within
the specified limits.
CAUTION Do not apply more than 300V between plug-in module INPUT or SENSE H and L
terminal, or between any adjacent channels, or instrument damage could occur.
Follow these steps to verify resistance accuracy:
1. Using shielded Teflon or equivalent cables in a 4-wire configuration, connect the Model 7708 CH1 H and L INPUT termi-
nals, and CH21 H and L SENSE terminals to the calibrator as shown in
2. Install the Model 7708 in Slot 1 of the Model 27xx, turn on the power, and allow the unit to warm up for two hours before
proceeding. Be sure the front panel INPUTS switch is set to the REAR position.
3. Set the calibrator for 4-wire resistance with external sense on.
4. Select the Model 27xx 4-wire resistance function by pressing the Ω4 key. Close Channel 1 by pressing the CLOSE key
and keying in 101.
Figure 11
Connections for resistance verification (100Ω to 10MΩ) ranges)
CH1
H L
H L H L H L
CH2 CH3 CH4
CH1
CH21
16
H L
H L
CH1 CH2
H L H L H L H L
H L H L H L H L H L
CH5 CH6 CH7 CH8 CH9 CH10 CH11 CH12 CH13
Model 7708
Figure
Output
HI
Output
LO
H L
CH14
11.
Sense
HI
Resistance Calibrator
Sense
LO
Note: Use shielded, low-thermal cables
to minimize noise. Enable or disable
calibrator external sense as indicated
in procedure.