Voltmeter Gain Adjustments; Voltmeter Frequency Response Adjustment; Sensitivity Switch Calibration - HP 333A Technical Manual

TM 11-6625-1576-15
Section V
Paragraphs 5-30 to 5-32
If the 60 on the Frequency dial is not under
the cursor after step j is completed, refer
to Figure 7-1 and perform the following
steps:
1) Remove set screws (#2) from knob on Frequency
dial, and then remove knob (#31). Do not change
C4 setting.
2) Loosen retaining screws on Frequency dial (#3),
and slip dial until 60 is under cursor, being
careful not to disturb C4 setting.
3) Tighten retaining screws and replace knob and
set screws.
5-30.

VOLTMETER GAIN ADJUSTMENTS.

Connect Voltmeter Calibrator (-hp- Model
a.
738BR) to Distortion Analyzer as shown in Figure 5-5.
Remove shorting bar between earth ground and floating
ground terminals.
b. Set Distortion Analyzer controls as follows:
FUNCTION Selector . . . . . . . VOLTMETER
METER RANGE Selector . . . .0.001 VOLTS
c. Set Voltmeter Calibrator to 400 ˜ RMS, 1.0
millivolt output.
d. Adjust A2R34 (400 cps CAL. 2) for a meter in-
dication of 1.0.
e. Set Voltmeter Calibrator to 400 ~ RMS, O. 3
millivolt output.
RANGE selector to 0.0003 VOLTS.
f. The meter shall indicate 3.0 ± 1/3 of a minor
division (±O. 55%). If necessary, change A2R30 to set
reading within these limits,
If transistors are replaced in the meter
amplifier, it may be necessary to change
A2R30. Typical values for this resistor
are between 140-260 ohms.
resistance decreases the meter reading
and vice versa.
g. Perform the Voltmeter Accuracy Check of Para-
graph 5-17. The meter shall indicate within the
limits specified.
5-31. VOLTMETER FREQUENCY RESPONSE
ADJUSTMENT.
a. Connect the test equipment to the 333A/334A as
shown in Figure 5-6.
Range switch cover must be in place be-
fore performing these adjustments.
b. Set the Distortion Analyzer controls as follows:
FUNCTION Selector . . . . . . . VOLTMETER
METER RANGE Selector . . . 0.0003 VOLTS
c. Set the frequency response test set for 400 cps
ad adjust the output amplitude for a Distortion Ana-
lyzer meter indication of 0.9 on the 1.0 scale.
5-10
NOTE
Set Distortion Analyzer METER
NOTE
Increasing
NOTE
d. Adjust the frequency response test set meter
control for a set level indication
e. Change frequency response test set frequency t'
20 cps.
f. Readjust the amplitude until the frequency re-
sponse test set meter indicates set level.
g. The Distortion Analyzer meter shall indicate
0.9 ± 5%.
NOTE
If reading exceeds these limits, change
A2C25. Typical value for this capacitor
is between 50 and 200 µf. Increasing ca-
pacitance reduces the meter reading, and
vice versa.
h. Switch Distortion Analyzer METER RANGE
selector to O. 001 VOLTS, Repeat steps c and d.
j. Change frequency response test set to 5 cps.
Repeat step f.
k. The Distortion Analyzer meter shall indicate
0.9 ± 5%.
m. Switch the Distortion Analyzer METER RANGE
selector to O. 01 VOLTS. Repeat steps c and d.
n. Adjust frequency response test set frequency
for 2Mc and adjust the output amplitude until the fre-
quency response test set indicates set level.
p. Adjust A2R39 (GAIN ADJUST) for a Distortion
Analyzer meter indication of O. 9 on the 1.0 scale.
q. Change the frequency response test set frequen-
cy to 3 Mc. Readjust the output amplitude until the
frequency response test set indicates set level.
r. Adjust A2C21 (3 Mc CAL trimmer) for a Dis-
tortion Analyzer meter Indication of O. 9 on the 1.0
scale.
NOTE
The frequency response adjustments made
thus far interact, It will be necessary to
repeat steps n thru r until all adjustments
are within specifications.
s. Switch Distortion Analyzer METER RANGE to
O. 3 VOLTS. Repeat steps c and d.
t. Change the frequency response test set frequen-
cy to 2.5 Mc. Readjust the output amplitude until the
meter indicates set level. Adjust S3C6 (VOLTAGE
CAL at 2.5 Mc O. 3 v RANGE trimmer) for a Distor-
tion Analyzer meter indication of O. 9 on the 1.0 scale.
v. Switch the Distortion Analyzer METER RANGE
selector to 3 VOLTS. Repeat steps c and d.
w. Change the frequency response test set frequen-
cy to 200 Kc. Repeat step f.
x. Adjust S3C1 (200 Kc CAL) for a Distortion Ana-
lyzer indication of O. 9 on the 1.0 scale.

5-32. SENSITIVITY SWITCH CALIBRATION.

a. Connect instruments as shown in Figure 5-6.
Model 333A/334A