2. Service
Assembly/Module Diagnostic Trees (Diagnostic Section 3)
124
3.9.1.7 A19 Signal-Frequency Test
1
Connect the output of the semi-rigid cable to the frequency counter
with a 50
Ω
input terminator.
2
Observe the A19 frequency with an accuracy of
±
1Hz. (The counter timebase
must be calibrated to an accuracy of better than 1
×
10
-7
.)
3
Calculate the nominal output frequency of the A19 from the EFC control
percentage using the equation:
Freq_nom = 10.0 MHz + 0.0331*(%Ctrl) Hz.
4
Verify that the measured frequency agrees with the calculated frequency to
±
2 Hz.
QUESTION:
Does the measured frequency agree with the calculated
frequency
to
±
2 Hz?
If Yes:
The A19 reference-oscillator chain has checked-out correctly.
If No:
Go to, 3.9.1.8.
3.9.1.8 A19 VCXO Set-Point Adjustment
The following procedure attempts to adjust the VCXO set-point.
It should be carried out if the A19 appears to have aged out of tolerance, or if
a new A19 has been installed.
1
Remove the cover plate from the left side of the instrument as seen from the
front.
2
Observe the frequency output of A19 as described in procedure 3.9.1.7.
3
Using a non-conducting screwdriver, adjust the VCXO mechanical trimmer
accessible through a hole in the left-hand chassis side-rail, to bring the
frequency within 1 Hz of its calculated nominal value.
4
Carefully withdraw the screwdriver.
QUESTION:
Can the frequency be correctly adjusted?
If Yes:
The procedure is complete and the A19 VCXO-chain operation
has been verified.
If No:
Remove power, replace A19, and retest.
Содержание 5071A
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Страница 40: ...1 Performance Tests Verifying Specifications 5071A Complete Performance Tests 24 ...
Страница 48: ...2 Service Pre Troubleshooting Information 32 Figure 2 1 Instrument Top View ...
Страница 147: ...3 Theory of Operation Functional Block Descriptions 131 Figure 3 2 5071A Overall Block Diagram ...
Страница 148: ...3 Theory of Operation Functional Block Descriptions 132 Figure 3 2 5071A Overall Block Diagram Continued ...
Страница 164: ...3 Theory of Operation Functional Block Descriptions 148 Figure 3 3 A1 Power Supply Distribution Schematic Diagram ...
Страница 166: ...3 Theory of Operation Functional Block Descriptions 150 Figure 3 4 A1 Slot Module Interconnect Diagram ...
Страница 168: ...3 Theory of Operation Functional Block Descriptions 152 Figure 3 5 Power Supply Block Diagram ...
Страница 171: ...3 Theory of Operation Functional Block Descriptions 155 Figure 3 7 Opt 048 A1 Slot Module Interconnect Diagram ...
Страница 172: ...3 Theory of Operation Functional Block Descriptions 156 Figure 3 8 Opt 048 Power Supply Block Diagram ...
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Страница 175: ...3 Theory of Operation Functional Block Descriptions 159 Figure 3 9 A1 Component Locator Diagram ...
Страница 194: ...5 Replaceable Parts How To Order A Part 178 ...
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