c. The NULL switch is set to the least sensitive range (i.e., fully
counterclockwise).
d. The voltage readout dials are set to the approximate magnitude of
the unknown voltage.
e. The unknown voltage source is connected to the INPUT and COMMON
terminals.
If one of the voltage-source terminals is grounded, it is
connected to the COMMON terminal.
f. The voltage readout dials are adjusted for a zero indication on the
meter, while turning the NULL switch to successively more sensitive positions.
g. The magnitude of the unknown voltage is read from the readout dials.
h. Fluctuations in the unknown voltage can be measured by observing the
excursions of the meter needle. Full scale meter calibration is determined
by the setting of the NULL switch.
7.
When operating the instrument as an ac differential voltmeter, if the
approximate input voltage is not known, determine it by using the voltmeter
in the ac TVM mode.
a. Correct meter zeroing is verified as in paragraph 4.
b. The RANGE switch is set to the lowest range setting that includes
the unknown voltage.
c. The NULL switch is set to the least sensitive position (i.e., fully
counterclockwise).
d. The voltage readout dials are set to the approximate magnitude of
the unknown voltage.
e. The unknown voltage is connected to the INPUT and COMMON terminals.
f. The voltage readout dials are adjusted for a zero indication on the
meter, while turning the NULL switch to successively more sensitive positions.
g. The magnitude of the unknown voltage is read from the readout dials.
h. Fluctuations in the unknown voltage can be measured by observing the
excursions of the meter needle. Full scale meter calibration is determined
by the setting of the NULL switch.
8.
When recording voltage excursions about a nominal value, correct meter
zeroing is verified as in paragraph 4 and the ac-dc polarity switch is set
to the desired position.
a. The input voltage is connected between the INPUT and COMMON
terminals.
If one side is grounded, it is connected to the COMMON post.
Deflection of the meter needle to the left indicates a negative voltage at
the INPUT terminal. The polarity switch is turned to negative.
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