HP 400D Operating And Service Manual

T.O. 33A1-12-349-1
Section V
DISCONNECT CHASSIS GROUNDS
AT ADAPTERS
CN-I6/U
VARIABLE
TRANSFORMER
oureut
VOLTMETER CALIBRATOR
HEWLETT-PACKARD MODEL 738BR
VOLTMETER
UNDER TEST
Figure 5-6. Test Setup for Calibration Check and Adjustments
The residual reading on voltmeter must be no higher
than the residual reading obtained with voltmeter INPUT
terminated with a 10-megohm resistor and shielded to
prevent stray pickup. If the residual reading is higher
when connected to the calibrator, refer to paragraph 3-12.
e.
Set
the
voltmeter
RANGE
switch
to
.001.
Set the
voltmeter
calibrator
to
provide.
001
volt
rms
(400
cps)
output.
Record
deviation
of
voltmeter
reading
from
1
on
the
voltmeter
scale.
f. Set the voltmeter RANGE switch to 1. Set the
voltmeter calibrator to provide 1 volt rms output. Re-
cord deviation of voltmeter reading from 1 on the volt-
meter scale.
g. Still using the voltmeter 1-volt range, reduce the
voltmeter calibrator output in 0. t volt steps. Record
deviation of voltmeter readings from each 0. 1 volt cali-
bration mark.
h. Compare recorded deviations with the permissible
errors listed in the performance specifications in
figure 1-2,
i. Connect the voltmeter as shown in figure 5-7
and set line voltage to 115. (This setup measures
calibration accuracy at low and high frequencies.)
j. Set voltmeter RANGE switch to .001. Set frequency
response test set OUTPUT ATTENUATOR to .001 to
measure the lowest voltmeter range; initially set
AMPLITUDE control for 0 volts output. Then note volt-
00102-3
meter reading; it must not be higher than the residual
reading noted in step a.
k. Turn the frequency response test set RANGE
SELECTOR
to
EXTERNAL.
Set
the
external
oscillator
frequency to 400 cps; adjust the oscillator output level
to obtain a reading of .9 on the 0 to 1 VOLTS scale of
the
voltmeter.
Then
adjust
the
METER
SET
control
on
the
frequency
response
test
set
to
obtain
a
standard
meter indication at the SET LEVEL mark on the test
set meter.
1. Tune the external oscillator to 10 cps and adjust
its
output
level
to
keep
the
frequency
response
test
set
meter reading at SET LEVEL. Do not adjust the METER
SET control as this would alter the fixed monitoring
point of the meter, Record the voltmeter deviation
from .9 on the scale. This reading must be between
0.85 and 0.95 to be within specifications.
m.
Set
the
RANGE
SELECTOR
on
the
test
set
to
3-10
mc,
set
the
FREQ.
TUNING
dial
to
4,
and
adjust
the
AMPLITUDE
control
to
keep
the
frequency
response
test
set
meter
reading
at
SET
LEVEL.
Record
the
voltmeter
deviation
from
.9
on
the
scale.
This
reading
must
be
between
0.85
and
0.95
to
be
within
specifications.
The
gain
and
frequency
response
of
the
basic
voltmeter
amplifier
is
now
tested.
n, Repeat step m using line voltages of 103 and 127.
Record voltmeter deviation from .9 on the scale.
o. Set voltmeter RANGE switch to .003 and also set
the frequency response test set OUTPUT ATTENUATOR
to
.003
to
check
this
voltmeter
range.
Repeat
steps
k
and
m,
Record
voltmeter
deviation
from
.9
on
the
scale.
5-7

HP 400D Specifications

General

Brand	HP
Model	400D
Category	Measuring Instruments
Language	English