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Model 654A
Section V
SECTION V
MAINTENANCE
5-1. INTRODUCTION.
5-2. This
section
contains
maintenance
and
service
information for the -hp- Model 654A Test Oscillator.
Included are performance checks and adjustment and
calibration procedures.
5-3. Table 5-1 lists the equipment required to properly
maintain the Model 654A. If the recommended model is
not available, any instrument that has specifications equal
to, or better than, the required specifications may be used.
5-4. PERFORMANCE CHECKS.
5-5. The performance checks are in-cabinet tests (except
where noted) to compare. the performance of the Model
654A with the specifications given in Table 1-1. These
checks may be used for incoming inspection, periodic
maintenance and for performance checks after a repair. The
Performance Check Test card at the end of Section V may
be cut out and used as a permanent record of the
instrument's performance during incoming inspection. It is
recommended that performance checks and, if necessary,
calibration be performed every 90 days.
5-6. FREQUENCY CHECKS.
5-7. FREQUENCY RANGE CHECK.
a. Connect an electronic counter to the 654A rear
panel COUNTER OUTPUT.
b. Set the 654A controls as follows:
FREQUENCY RANGE
X10
FREQUENCY dial
Extreme clockwise
c. The counter should indicate a period average of
100ms or greater, verifying a frequency of 10Hz,
or less, at the lower end of the frequency range.
d. Set the FREQUENCY RANGE switch to X1M and
FREQUENCY
dial
to
its
extreme
counter-clockwise postiton. The counter should
indicate
a frequency
of 10MHz, or greater,
verifying a frequency of at least 10MHz at the
upper end of the frequency range.
e. Perform the Frequency Adjustments (Paragraphs
547 through 5-57) if the tolerances are not met.
5-8. FREQUENCY ACCURACY CHECK.
a. Connect an electronic counter to the 654A rear
panel COUNTER OUTPUT.
b. Set the 654A controls as follows:
FREQUENCY RANGE
X10
FREQUENCY dial
1
c. Verify frequency accuracy using the settings and
tolerances given in Table 5-2. Use the period
average setting on the counter for frequencies
below lkHz and use the frequency setting for
frequencies above IkHz.
d. Perform the frequency adjustments (Paragraphs
5-47 through 5-57) if the tolerances are not met.
5-9. AMPLITUDE ACCURACY CHECKS.
(See also Table 3-1, Page 3-1)
5-10. 50 UNBAL AMPLITUDE ACCURACY.
a. Connect the equipment as shown in Figure 5-1.
Use the 50 ohm Feedthrough termination which
should be connected directly to the 654A output
connector.
b. Set the 654A controls as follows:
FREQUENCY dial
1
FREQUENCY RANGE
X1K
OUTPUT LEVEL dBm
+ 10,0
IMPEDANCE
50 UNBAL
AMPLITUDE
Adjust for OdBm
on 654A meter.
c. The ac differential voltmeter indication should be
between .7000V rms and . 7142V rms verifying an
absolute level of + 10dBm, +/- 1%.
d. If the tolerances are not met perform the Meter
Tracking and Amplitude Control Adjustments of
Paragraphs 5-58 through 5-60.
5-11. 75 UNBAL AMPLITUDE ACCURACY.
a. Perform the procedure of Paragraph 5-10 except:
in
step
a. Use
the
75
ohm
feedthrough
termination;
5-1
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