TB 9-6625-975-24
CALIBRATION PROCESS FOR I-48( ), ZM-21( )/U, BIDDLE, MODELS 679, 7676,
7676-1, 7679, 7679-1, AND 210359
6. Preliminary Instructions
a. The instructions outlined in paragraphs 6 and 7 are preparatory to the calibration
process. Personnel should become familiar with the entire bulletin before beginning the
calibration.
b. Items of equipment used in this procedure are referenced within the text by common
name and item identification number as listed in tables 2.
c. Unless otherwise specified, verify the result of each test and, whenever the test
requirement is not met, take corrective action before continuing with the calibration.
Additional maintenance information is contained in the manufacturers' manuals and
TM 11-2050, and TM 11-6625-298-14 for these TI's.
d. Unless otherwise specified all controls and controls settings refer to the TI.
7. Equipment Setup
WARNING
HIGH VOLTAGE is used or exposed during the performance of
this calibration.
DEATH ON CONTACT may result if
personnel fail to observe safety precautions.
REDUCE
OUTPUT(S) to minimum after each step within the
performance check where applicable.
a. Remove TI from carrying case.
b. Place TI on a firm, level base and avoid large deposits of iron and magnetic fields.
8. Meter Range
a. Performance Check
(1) Connect LINE and GROUND terminals of TI together.
NOTE
The meter pointer may stand anywhere over the scale until TI
is operated.
(2) Rotate generator crank cw at normal operating speed. Meter will indicate ZERO.
NOTE
To obtain a correct indication on TI meter, the hand-operated
generator crank must be rotated cw at normal operating speed.
The generator reaches operating speed when centrifugal clutch
begins to slip.
(3) Disconnect shorting lead from LINE and GROUND terminals and rotate
generator crank. Meter pointer will indicate INFINITY.
b. Adjustments. No adjustments can be made.