HP 3456A Operating And Service Manual page 74

Adjustments
e. Do the same for the I V, 10 V, 100 V, and 1000 V
ranges.
f. Set the 3456A to Autorange and remove the short.
g. Set the DC Transfer Standard for a
and connect it to the 3456A's VOLTS input terminals.
Make sure the " + " output is connected to the 3456A's
VOLTS HIGH terminal.
h. Adjust the 3456A's calibration potentiometer " 8"
for a + 10.0000 0 V
I count reading on the display. If
±
"unable" to adjust to the required reading, go to the
next step. If "able" to adjust to the required reading, go
to Step j.
i. Do the following:
1 . Turn calibration potentiometer "8" completely
counterclockwise.
2. Turn adjustment "A" until the 3456A's reading is
as close to + 10 V as possible. If the reading is
+
higher than 10.0000 0 V, turn adjustment "A"
one position for a less than + 10 V reading.
3 . Adjust calibration pot "8" for a + 10.0000 0
count reading.
j . Set the Transfer Standard for a + I V output.
k. Adjust calibration pot "C" for a + 1 .0000 00 V
1 count reading.
±
1. Disconnect the DC Transfer Standard from the
3456A's input.
m. Set the 3456A to the 100 mV (100 -3) range and
short its input terminals.
n. Turn on the 3456A's Null Math feature. Remove
the short after the instrument has taken a reading.
o. Using short pieces of number 20 A WG (or thinner)
insulated solid copper wires, connect the Transfer Stan­
dard and the DC Null Voltmeter to the Reference
Divider as shown in Figure 5-2 and 5-3.
p. Turn the DC Standard's output off. Using 24 inch
or shorter shielded cables equipped with banana-plug
connectors, connect the DC Standard and the 3456A to
the Reference Divider as shown in Figure 5-2 and 5-3.
q. Set the Standard Cell Voltage switches on the
Reference Divider to correspond with the output voltage
setting of the Transfer Standard. Normally the Transfer
Standard's switches should be set to the voltage value of
the Standard Cell used to calibrate the Transfer Stan­
dard.
5-6
r. Zero the DC Null Voltmeter on the 3 microvolt
range and then set it to the 300 microvolt range.
s. Set the Reference Divider's Input Voltage switch to
100 V and center its Coarse and Fine Adjust controls.
+
10 V output
Set the Reference Divider's Output voltage switch
1.
to . 1 V.
u. Set the DC Standard for an output voltage of
+ 1 00 V and turn its output on.
v. Set the Reference Divider's Standard Cell switch
to the "Locked" position. Adjust the DC Standards
Output for a zero reading on the DC Null Voltmeter.
w. Downrange the DC Null Voltmeter and adjust the
Reference Divider's Coarse and Fine controls for a
"Null" reading (0 reading) on the Null Voltmeter's 3
microvolt range.
x. Set the Reference Divider's Standard Cell switch
to the OPEN posit ion.
y. Set the Reference Divider's Standard Cell switch
to MOMENTARY, and if necessary, readjust the Di­
I vider's Fine Control for a null indication on the Null
±
Voltmeter. Release the Standard Cell switch.
The Divider's Fine Control may have to
read justed, when the Output Voltage switch
is
z. Adjust the 3456A's calibration pot
+ 100.0000 -3 V
Turn the 3456A's Math operation off.
aa.
bb. Uprange the 3456A to the 100 V range.
cc. Uprange the Reference Divider's Output Voltage
switch to 1 00 V. Adjust the 3456A's calibration pot
"E" for a + 100.0000 V
Always uprange the R e f erence Divider's In­
put Voltage switch b e f ore upranging Stan­
dard before downranging the Ref erence
Divider's Input Voltage switch.
dd. Uprange the Reference Divider Input Voltage
switch to 1000 V and then uprange the DC Standard to
+
1000 V. Allow about ten minutes for the Reference
Divider to warm-up and stabilize.
NOTE
set to another position.
5 counts reading.
±
±
I count reading.
Model 3456A
be
"0"
for a