Section Iv Calibration Process - HP 431B Calibration Procedure

Unless otherwise specified, verify the results of each test and
take corrective action whenever the test requirement is not
met before continuing with the calibration.
When indications specified in paragraphs 8 through 11 are not
within tolerance, perform the oscillator frequency check in
paragraph 12 and the power supply check in paragraph 13
before making adjustments. Do not perform the procedures in
paragraphs 12 and 13 if all other parameters are within
tolerance.
Remove top and side covers from the TI only for adjustment.
When adjustment is completed, reinstall the covers.
8. Coarse Null
a. Performance Check
(1) Position the TI RANGE switch to the .01 MW position.
(2) Adjust the TI ZERO controls for a 25 to 75 percent indication on the TI meter.
(3) Turn the RANGE switch to NULL.
(4) Adjust the NULL, control for minimum indication on the TI meter.
(5) Repeat (2) through (4) above until the TI meter pointer is within the NULL
region. If the meter pointer does not indicate within the NULL region, perform b below.
During maintenance calibration, if a 100-ohm thermistor
mount is not available, disregard (6) through (8) below.
(6) Connect 100-ohm thermistor mount (A8) to the TI.
(7) Set the TI MOUNT RES switch to 100.
(8) Repeat (2) through (5) above.
b. Adjustments. On model 431C, adjust L1 (fig. 1)(L102, fig. 2 on model 431B) for
null on the TI.
SECTION IV
CALIBRATION PROCESS
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TB 9-6625-086-35
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