Keithley 7708 User Manual page 26

Verifying ratio and average
Follow the procedure below to verify ratio and average.
CAUTION Exceeding 300V between plug-in module INPUT or SENSE H and L terminals may
cause instrument damage.
1. Connect the Model 7708 CH1 and CH21 H and L terminals to the DC 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. Select the Model 27xx DCV function and the 1V range. Close Channel 1 by pressing the CLOSE key and keying in 101.
4. Select the Model 27xx RATIO function (press SHIFT then RATIO).
5. Set the calibrator output to 1.00000V DC, and allow the reading to settle.
6. Verify that the ratio reading is between 0.9999926 and 1.000074.
7. Press OPEN to open Channel 1.
Figure 15
Connections for ratio and average verification
CH1
H L H L H L H L
CH4
CH1 CH2 CH3
CH21
22
H L H L
CH2
CH1
H L H L H L H L H L H L H L H L H L
CH6 CH7 CH9 CH11 CH12 CH13
CH5 CH8 CH10
Model 7708
Output
LO
H L
CH14
Figure 15.
Output
HI
DC Voltage Calibrator
Note: Use shielded cables to minimize
noise.