8508A
Users Manual
Range Zero and Gain Adjustment Procedure
After the initial setup and connecting up, use the following procedure to adjust range zero
and range gain for the ranges and points detailed in Table 6-5 for the HiVΩ mode. Just
one range can be adjusted if required, but for a full adjustment start with the 20 MΩ
range and work up to the 20 GΩ range.
For the 2 GΩ range use the 1 GΩ standard resistor in place of the calibrator. To avoid the
requirement for a 10 GΩ standard, the 20 GΩ range is automatically adjusted when the 2
GΩ range gain adjustment is triggered. A 10 GΩ standard resistor may be used for
adjusting the 20 GΩ range if available, but if performed, this operation must take place
after the 2 GΩ range gain point adjustment to avoid the automatic process overwriting the
result.
Voltages of approximately 200 V will be developed across the resistance standard at full
scale, ensure the resistance standards used are suitable for operation at these voltages.
Note that EX SNS (4-wire) is not available on the 5720A 100 MΩ range, and the 8508-
7000K 1 GΩ standard resistor is used as a 2-wire device with the calibrator 2-wire
resistance zero used for the corresponding zero points.
4WΩ is deselected on the 8508A
when adjusting the 200 MΩ and 2 GΩ range, range zero, and range gain points.
On each range, the 8508A automatically recognizes the appropriate value as range zero or
range gain from the applied resistance value.
Note
It is unlikely that the resistance standard will be at exactly the nominal value
required. The Set feature allows a user to enter the true output value of the
calibration standard where it differs from nominal range gain point. If the
resistance value is exactly the nominal value required, omit step 6 for the
Range Gain Point .
6-26
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