HP 3457A Service Manual page 127

d. Repeat steps "cl " through " c4" for each of the remaining ranges.
e. Remove the shorting wires from the Front Panel Q Source and Input terminals.
5-33. Four-Wire Ohms Gain Calibration - Front Terminals
5-34, Equipment Required. Resistance Standards capable of providing 30 Ohms (4.2%), 300 Ohms (+,02%),
3 Kohm (4.003%), 30 Kohms (+.001%), 300 Kohms (+.001%), 3 Mohms (+.002%) and 30 Mohms (+.009%) are
required to calibrate the 4-Wire Ohms Function.
"_ RESISTANCE
STANDARD
Figure 5-2. Input Connections for 4-Wire Ohms Gain Calibration
a. Run the Ohms Auto-Calibration routine. (Press the AUTO CAL configuration key, enter the number 3 and
press the ENT key).
b. Set the Resistance Standard to 30 MOhms and connect it to the HP 3457A front panel HI and LO
Input terminals and Q Sense HI and LO terminals as shown in Figure 5-2.
c. Use the following procedure to calibrate the Gain on the 30 Mohm, 3 Mohm, 300 Kohm, 30 Kohm,
3 Kohm, 300 Ohm and 30 Ohm ranges beginning with the 30 Mohm range.
1. Set the 3457A to the appropriate Resistance range. (Use the if or J scroll key to select the proper
range).
2, Set the resistance standard to the full-scale resistance of HP 3457A range selected.
3. Access the Calibration Command. (Press the Blue SHIFT key, then the OFFSET COMP / C configura-
tion key). The display will show CAL.
4. Enter the value of the input resistance (in ohms). (NOTE: If the security feature has not been disabled
(set to 0), it will be necessary to enter the input value, the delimiter ( , ) and the security code).
5. Press the ENT key. The display will show CALIBRATING while the calibration routine is
running.
5-9