Fluke 893A - Versus Range Checks; Null Detector

n. Connect
the
output of the
dc voltage calibrator
between
the
LO and
HI INPUT terminals.
o. Apply
the dc
input
voltages versus the
ranges in-
dicated in
Figure
4-5, observing that the meter
indicates
full-scale
(+1)
± 1
-
1/2
small divisions.
4-30.
When
the results
of the
checks agree with the
information
given, the
Null
Detector and
Divider cir-
cuitry
are functioning
properly
and the test equipment
can be
disconnected
from the
instrument.
INPUT
DC VOLTAGE
RANGE
NULL
SENS
.001
1
1 mv
.01
1
. Olv
. 1
1
. 1 v
1.0
1 TVM
10.0
10
TVM
100.0
100
TVM
1000.0
1000
TVM
Figure
4-5.
INPUT DC
VOLTAGE
VERSUS
RANGE-CHECKS
4-31.
KELVIN-VARLEY
DIVIDER
CHECKS
4-32.
The Kelvin-
Varley Divider
Checks require
the
use
of
a
dc voltage
calibrator.
The
Precalibration and
Troubleshooting
Checks of
paragraphs 4-21 through
4-30
must also have
been performed
to
ascertain that
the
associated
Instrument
circuitry
is functioning
correctly.
To perform
the checks,
apply
ac power
to the
instrument
and proceed
as follows:
a.
Place the Model 893
controls
as follows:
POWER
RANGE
NULL SENS
MODE
Readout dials
ON/LTNE
OPR
10
.001
+
10.
000
-
A4TP11
FULL-SCALE INPUT
Ft"".
;
5
u
SATURATION
CONDITION
4
1
:ffz
5
u —j
C
-
—
c
T...
u
A4TP13
A4TP15
Note:
HORIZONTAL
SWEEP
-
5
MSEC/CM
Figure
4-6.
NULL DETECTOR
WAVEFORMS
4-10
b. Apply
+10
volts
dc from
a dc voltage
calibrator
between
the
Model 893
LO
and HI
INPUT
terminals.
c.
Adjust
A2R33
for a zero-center
meter
indication
on the
Model
893
.
d. Apply the
dc
input
voltages
versus the
Readout
dial
settings
of Figure
4-7, observing
that the
Model
893 meter
indicates
zero-center
within the
major division
deviation.
INPUT
DC VOLTAGE
READOUT
DIAL
SETTINGS
MAJOR
DIVISION
DEVIATION
11.000
10. 99
X
±5.5
10.
000
10.00
0
null
reference
10. 00
9-99
X
±5. 0
9.999
9. 99
90
±4. 99
8. 888
8. 88
80 ±4,
44
7.777
'^77
20
±3. 88
6.666
6.66
^
±3.33
5.555
5.55
5(}
±2.77
4.444
4.44
40
±2.
22
3,333
3-33 30
±1,
66
2.222
2,22
20
±1.
n
1.111
1. 11 10
±
.55
1.000
1.00
Q
±
.5
Figure
4-7.
INPUT
VOLTAGES
VERSUS
READOUT
SETTINGS
-
CHECKS
4-33.
When
the results
of these
checks
agree with the
information
given, the
Kelvin-
Varley Divider
circuitry
is
functioning
properly
and the
test equipment
can be
disconnected
from the
instrument.
4-34.
RECORDER
OUTPUT
OPTION
CHECKS
4-35.
The
Recorder
Output
Option Checks
require
the
use
of a dc
differential
voltmeter.
Circuit
wave-
forms
are illustrated
in
Figure
4-8,
To
perform the
checks,
apply
ac power to the
instrument
and proceed
as
follows;
a. Connect the
inputs
of a dc differential
voltmeter
to
the
rear panel
HI and
LO
RECORDER OUTPUT
terminals and
rotate the
associated
level control
fully clockwise.
b. Connect
a shorting
jumper between
the
LO and
HI
INPUT
terminals
of the
Model
893
and
place the
controls
as follows:
POWER
RANGE
NULL SENS
MODE
Readout
dials
ON/LINE
OPR
1
.001
+
.00100
c. A
dc voltage
of
-0.
2 to
-0.
28 volts
dc should be
indicated
on the
dc differential
voltmeter
connected
to the
RECORDER
OUTPUT
terminals.
893A