TM 9-4935-282-34
803D
e. Set null switch to 0.1 and then 0.01 volt, adjusting
2-7. MEASUREMENT OF VOLTAGE EXCURSIONS ABOUT
voltage dials for zero meter deflection in each position.
A NOMINAL VALUE
f. Read unknown voltage from the five voltage readout
dials.
a. After completing preliminary operation as stated in
2-6. OPERATION AS A CONVENTIONAL VTVM
b. Connect voltage to be observed to input binding
posts. If meter reads to the left, the voltage being measured is
If it is desired to use the instrument as a VTVM on additional
negative DC; set polarity switch to the negative position in this
ranges can be made available by converting the NULL ranges
case. This will cause meter pointer to defect to the right.
to VTVM ranges. This is made possible by setting the voltage
c. Set RANGE s witch to lowest range which will give an
readout dials to zero. Proceed as follows:
on-scale meter indication and note nominal value of voltage
a. Perform preliminary operation procedures as stated in
indicated.
d. Set the five voltage readout dials to nominal voltage.
b. Consult figure 2-3, and select full scale voltage
e. Turn NULL switch to lowest position that will allow
deflection desired. If the approximate value of the voltage to
voltage excursions to remain on scale.
be measured is unknown, select the 500 volt range initially.
f. Read voltage excursions from meter. Note that full
c. Set AC - DC polarity switch, RANGE switch, NULL
scale right and left meter deflections are equal to the NULL
switch, and voltage dials as indicated for the range selected.
voltage setting for DC measurements. For AC measurements,
d. Connect voltage to be measured to input binding
full scale right and left meter deflections are equal to the NULL
posts. Deflection to the right indicates that an unknown DC
voltage setting multiplied by the AC NULL MULT indicated by
voltage is of positive polarity. An unknown AC voltage will
the RANGE setting. Figure 2-4 shows full scale AC deflections
always cause deflection to the right.
for the recommended settings of the range and null switches.
e. Read voltage from upper or lower scale as listed in
AC-DC
Voltage
Full-Scale
Polarity
Range
Null
Readout
Meter
Deflection
Switch
Switch
Switch
Dials
Scale
DC:
500-0-500
+
500
VTVM
No effect
Upper
50-0-50
+
50
VTVM
No effect
Upper
5-0-5
+
5
VTVM
No effect
Upper
0.5-0-0.5
+
0.5
VTVM
No effect
Upper
10-0-10
+
No effect
10
All zero
Lower
1-0-1
+
No effect
1
All zero
Lower
0.1-0-0.1
+
No effect
0.1
All zero
Lower
0.01-0-0.01
+
No effect
0.01
All zero
Lower
0.001-0-0.001
+
No effect
0.001
All zero
Lower
AC:
0-500
AC
500
VTVM
No effect
Upper
0-50
AC
50
VTVM
No effect
Upper
0-5
AC
5
VTVM
No effect
Upper
0-0.5
AC
0.5
VTVM
No effect
Upper
0-100
AC
500
1
All zero
Lower
0-10
AC
500
0.1
All zero
Lower
50
1
0-1
AC
500
0.01
All zero
Lower
50
0.1
5
1
0-0.1
AC
50
0.01
All zero
Lower
5
0.1
0.5
1
0-0.01
AC
5
0.01
All zero
Lower
0.5
0.1
0-0.001
AC
0.5
0.01
All zero
Lower
Figure 2-3. VTVM RANGES
2-4
