Current Measurement - Sperry instruments SP-5A Operating Instructions Manual

take a measurement.
4) Apply the test leads to the two points in the circuit at which the
voltage is to be measured. When measuring DC voltage the black
lead should be connected to the more negative point of measure-
ment. When measuring AC voltage the polarity does not matter.
5) Read the AC or DC voltage using the V-MA scale directly below
the mirror scale. Use the numbers whose full-scale reading match-
es the range selected by the "Selector Switch". When using the
10Vac range the readings must be taken from the red scale marked
AC10V.
6) The dB scales can be used to measure the milliwatt power dissi-
pation in a 600 load by measuring the AC voltage across a 600
OHM load. An AC voltage of 0.775 Vrms across 600 OHMS is equal
to 1mW or "0" db. When converting an AC voltage measurement to
dB take the dB reading from the lowest arc on the scale plate and
then add the appropriate dB correction as listed in the chart printed
in the lower right corner of the instrument scale plate.
5-2) DC Current Measurement
1) Follow the Preparation for Use procedure in sec.4.
2) Read all Safety Precautions in sec.2.
250 mAdc is the maximum current that can be measured using
this meter. The instrument must be connected in series with the
circuit to be measured. Do not impress voltages across the "+"
and "-" terminals when set to the mAcd ranges. Doing so may
result in electric shock, instrument damage and/or damage to
CAUTION
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