Keithley 7708 User Manual page 18

3. Select the DC volts function by pressing the DCV key, and set the Model 27xx to the 100mV range. Close Channel 1 by
pressing the CLOSE key and then keying in 101.
4. Set the calibrator output to 0.00000mV DC, and allow the reading to settle.
5. Enable the Model 27xx REL mode. Leave REL enabled for the remainder of the DC volts verification tests.
6. Source positive and negative and full-scale voltages for each of the ranges listed in
sure that the reading is within stated limits.
7. Press the OPEN key to open Channel 1.
Table 3
DCV reading limits
Range Applied DC voltage*
100mV 100.0000mV
1V 1.000000V
10V 10.00000V
100V 100.0000V
1000V 300.000V
*Source positive and negative values for each range.
Verifying AC voltage
Check AC voltage accuracy by applying accurate AC voltages at specific frequencies from the AC voltage calibrator to the
Model 7708 inputs and verifying that the displayed readings fall within specified ranges.
CAUTION Do not exceed 300V RMS between plug-in module INPUT H and L terminals or
between adjacent channels, or 8 × 10
occur.
Follow these steps to verify AC voltage accuracy:
1. Connect the Model 7708 CH1 H and L INPUT terminals to the AC voltage 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 AC volts function by pressing the ACV key. Close Channel 1 by pressing the CLOSE key and then keying in
101.
14
Reading limits (1 year, 18° to 28°C)
99.9925 to 100.0075mV
0.999962 to 1.000038V
9.99965 to 10.00035V
99.9946 to 100.0054V
299.976 to 300.024V
7
V•Hz input, because instrument damage may
Table 3. For each voltage setting, be
Figure 10.