HP 400D Operating And Service Manual page 23

Section V
Paragraphs 5-24 to 5-26
T.O. 33A1-12-349-1
DISCONNECT CHASSIS GROUNDS
OSCILLATOR
HEWLETT-PACKARD MODEL 200S
AT ADAPTERS
ouTeuT
CN-I6/U
VARIABLE
TRANSFORMER
©),
©)
Féoo 8
FREQUENCY RESPONSE TEST SET
HEWLETT-PACKARD MODEL 739A
VOLTMETER UNDER TEST
Figure 5-7. Test Setup for Frequency Response Check and Adjustment
p. Set voltmeter RANGE switch to .01 and also set the
frequency response test set OUTPUT ATTENUATOR to
.01 to check this voltmeter range. Repeat steps k and m,
Record voltmeter deviation from .9 on the scale.
q. Set voltmeter RANGE switch to 1 and also set the
frequency response test set OUTPUT ATTENUATOR
to 1. Repeat step k.
r. Turn the frequency response test set RANGE
SELECTOR to EXTERNAL, Set external oscillator
frequency to 20 kc and adjust output level to keep the
frequency response test set meter reading at SET
LEVEL. Record voltmeter deviation from .9 on the
scale.
s. Repeat step m and record voltmeter deviation
from .9 on the scale.
t. The voltmeter is now completely tested. If the
measurements made have shown the voltmeter reading
to be within the tolerances given in the performance
specifications in Section I, the voltmeter is operating
satisfactorily. If operation is unsatisfactory, make
calibration and frequency reponse adjustments as
directed in paragraph 5-24,
5-8
5-24. CALIBRATION AND FREQUENCY RESPONSE
ADJUSTMENTS.
5-25. Calibration and frequency response adjustments
may be required when components other than those in
the power supply circuit are replaced. After replacing
any of these components, carry out the voltmeter
performance test of paragraph 5-22 to see if adjustments
are necessary. [If the voltmeter operates within specifi-
cations during the test of paragraph 5-22, with respect
to both calibration (at mid-frequencies) and frequency
response, no adjustments are needed. If operation at
mid-frequencies meets calibration specifications, only
the frequency response adjustments need be made.
Otherwise, make all calibration and frequency response
adjustments in the order listed in the following procedure.
5-26. Calibration of the voltmeter consists of five parts:
a. Setting the basic gain of the amplifier at 400 cps.
b. Setting the division ratio of the input attenuator
at 400 cps.
c. Setting the frequency response of the amplifier.
d. Setting the 4-mec frequency response of the step
attenuator.
00102-2