XD
©
METER Indicates the magnitude and poiarlt/ of the measured voltage
on the TVM mode. On
the
differential mode, the meter
or
-
deflection Indicates that the measured
voltage
is
above
or
below
the
readout dial
indication.
©
POWER
SWITCH Controls application of input power to the instrument. When
placed
to
the
LINE
OPR
position,
the instrument is operated from the
available
line power. On
Instruments
equipped with the 01 Option, additional switch positions
of
BAT CHK, BAT OPR-LINE
ISOL, and LINE
OPR-BAT
CHG
are
Included,
When
placed to
the BAT CHK
position
,
the front pane!
meter indicates the charge condition of
the
battery pack, A
meter
indication
of at
least
-.2
is required
before the
instrument
is to be operated from the
battery power. When placed to the BAT OPR-LINE ISOL position, the Insrument is
operated from battery power and the power transformer is completely disconnected from
line power.
However, to completely isolate
the
instniment
circuitry from power line
ground, the line power cord must be disconnected. When
placed to the LINE
OPR-BAT
CHG
position,
the
instrument
Is
operated from
line power and the battery pack Is being
charged
.
©
NULL SENS SWITCH Provides
selection of the TVM
mode
of operation and selection of the various
full-
scale
null detector sensitivity ranges when the instrument
is operated on the differential mode.
©
RANGE SWITCH Allows selection of the desired input
voltage range of
the instrument, while at
the same
time
simultaneously positioning the readout dial decimal
point
and
selecting the avail-
able
ranges of
the
NULL
SENS switch.
©
READOUT DIALS
Provide
an in-line
digital readout of the measured voltage when
the instrument
is
operated on the
differential mode.
©
MODE SWITCH Selects the AC or DC mode of operation. This
switch
should
be ploced to
the +
position
on
the DC TVM mode. The
±
positions
provide
a means of reversing
the
internal refer-
ence supply voltage on the dc
differential
mode.
2-2
Figure 2-1.
THE
MODEL
893A CONTROLS, TERMINALS,
AND
INDICATORS
(Sheet 1
of
2)
893A
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