HP 400F, Руководство по эксплуатации и обслуживанию, Страница: 21 / 54

ModeI400F/FL
Section V
Paragraphs 5-1 to 5-13
SECTION v
MAINTENANCE
5-1.
I N T R O DUC T I O N .
5-2. This section contains maintenance and service
information for the Model 400F/FL AC Voltmeter.
Included are Performance Checks, Alignment and
Calibration Procedures, and Troubleshooting Proce­
dures.
5-3. TEST E O U I P M E N T REOUI R E D .
5-4. The equipment required t o properly maintain the
400F/FL is listed in Table 5-1. The table lists the
type of equipment to beused, the spec111cation require­
ments, and the recommended commercially available
test equipment.
NOTE (400F only)
Before beginning the Performance
Tests, mechanically zero the meter
according to the procedures in Para­
graph 3-7.
5-5. P E R F O R M A N C E CHECKS.
5-6. The following Performance Checks compare the
400F/FL withits accuracy specllicaUons (Table 1-1).
These checks may be used for incoming inspection,
periodic maintenance, and for specification checks
alter a repair. A highly accurate and stable voltage
reference that is variable from 20 Hz to 4 MHz is re­
quired. The -hp- 73SBR Voltmeter Calibrator pro­
duces a 400 Hz signal that is within less than 0.2% of
the indicated output. The -hp- 652A Test Oscillator
can be referenced to the output of the 738BR and can
be adjusted to within
O.
25% of the set reference volt­
age from 20 Hz to 4 MHz.
5-7.
U
the -hp- 652A Test Oscillator is not available.
the 739AR Frequency Response Test Set and 200SR
Osclllator combination may be used. This combina­
tion can be adjusted to within O. 5% of a set voltage
reference from 20 Hz to 4 MHz. (The -hp- 739AR,
-hp- 200SR, and -hp- 73SBR are available in a rack
mounted configuration designated -hp- K02-738BR
VTVM Cal1braUon System. )
5-S. The following procedures specify the use of the
-hp- 652A and the -hp- 73SBR.
U
the K02-738BR
calibration system is used. follow the same general
procedures.
5-9. Figure 5-1 shows the test setup for USing the
-hp- 652A and -hp- 73SBR combination. Figure 5-2
shows the test setup for using the K02-73SBR VTVM
Calibration System.
01795-1
NOTE
The 0.1 mv range of the 400F/FL
may be checked for accuracy by
verification of the additional 10 db
of
gain
that is provided by the meter
amplifier on that range.
In
order
to verify the gain, the top cover of
the instrument must be removed to
gain access to TPl through TP4.
5-10. TOP COVER REMOVAL.
5-11. To remove or replace the top cover, follow the
procedures outlined
in
Paragraph 5-21.
5-12. ACCURACY AND FREQUENCY RESPONSE
CHECKS.
5-13. The accuracy and frequency response checks com­
pare the 400F/FL with its accuracy specifications
over the entire frequency range.
a. Connect the voltmeter calibrator and the Test
Oscillator to the 400F/FL as shown in Fig­
ure 5-1. An external switch (SI) may be used
to facilitate switching from one test instru­
ment to the other.
b. Set 400F/FL RANGE switch to 30 mv, and set
100 KHz F1LTER switch to OUT. Set switch
51 to Position A.
c. Adjust voltmeter calibrator for a 30 mv rms
output at 400 Hz,
d. Observe the 400F/FL meter indication.
U
the meter indication is not within the tolerances
listed in Table 5-2 (400F) or Table 5-3 (400FL),
perform the Meter Calibration (Paragraph
5-28).
e. Set 400F/FL RANGE switch to 100 mv, The
meter should indicate
30
mv.
e.
Short TP1 to TP4, and short TP2 to TP3.
(A shorting device, such as a crysta.l socket
with its terminals shorted together, should be
used to avoid piclrup of noise.) The meter
indication should be the same as the indicat ion
in step d of this paragraph (:t3 mv).
This
verifies the additional 10 db of galn that Is
provided by the meter amplifier on the
O.
1
I
mv range.
g. Set 400F/FL RANGE switch to 1 volt. and
disconnect shorts between test points.
h. Adjust voltmeter calibrator for a 1 volt output
at 400 Hz. Observe the 400F/FL meter in­
dication.
II
the meter indication is not within
the tolerances listed in Table 5-2 (400F) or
Table 5-3 (400FL). perform the Meter Cali­
bration (Paragraph 5-28).
i. Set switch 81 to Position B, and set 400F/FL
RANGE switch to
30
mv.
5-1