TM 9-4935-282-34
803D
CAUTION
Do not ground either of the 803D recorder
Range
Null
AC
Full Scale
output terminals or either of the A-70
Switch
Switch
Null
AC Deflection
input terminals. If any of these terminals
Setting
Setting
Multiplier
(in volts)
are grounded, current will be drawn from
1
100
the 803D Kelvin-Varley voltage divider
500
0.1
X100
10
and the accuracy of the 803D will be
0.01
1
completely destroyed.
1
10
50
0.1
X10
1
b. After connecting the recorder, perform preliminary
0.01
0.1
operation as stated in paragraph 2-3.
5
1
1
c. Check for excessive leakage as follows:
0.1
X1
0.1
(1) Connect a DC voltage to the input of the 803D
0.01
0.01
and differentially measure its potential in a recommended null
1
0.1
range.
0.1
X0.1
0.01
(2) Alternately connect and disconnect the
0.5
0.01
0.001
recorder leads from the output terminals of the 803D while
notting the meter needle deflection. More than one-quarter of
a small scale division deflection indicates that excessive
Figure 2-4. FULL SCALE AC DEFLECTIONS
leakage has been introduced by the recorder. This will impair
the accuracy of the 803D voltmeter.
2-8. USE OF 803D WITH A RECORDER
(3) Disconnect the voltage.
d. After the leakage test has been successfully
Recorder output binding posts and an output level control are
completed, short the input terminals of the 803D.
provided on the 803D for monitoring the excursions of an
e. Set switches on the 803D voltmeter as follows:
unknown voltage from the voltage indicated by the voltage dial
settings. If the leakage resistance between the recorder and
AC - DC polarity
+ (positive)
ground is less than 10,000 megohms, the accuracy of the
RANGE
50
803D will be impaired. Also, both input posts of the recorder
NULL
10
should be able to stand 500 volts DC to ground. Therefore, the
Voltage readout
10.000
John
Fluke
Model
A-70
Potentiometric
Recorder
dials
(manufactured by the Texas Instrument Co.) is recommended
for this application. Set up the recorder as follows:
The 803D meter will indicate full scale deflection. This
provides up to at least 18 millivolts at the output terminals
a. Connect A-70 recorder to 803D voltmeter with teflon
depending on the setting of the output level control.
leads as shown in figure 2-5.
f. Turn the output level control until the recorder
deflection obtained is that desired to correspond to full scale
deflection of the 803D.
g. Remove the short from the input terminals of the
803D. The 803D and the recorder are now ready for combined
use. Proceed as instructed under paragraph 2-7.
Figure 2-5. RECORDER RECOMMENDED CONNECTION DIAGRAM
2-5
