HP 8568B, Руководство по испытаниям и регулировке работы, Страница: 246 / 313

20. 50 MHz Voltage-Tuned Oscillator Adjustments
14. Adjust All POS SUPPLY for a DVM indication the same as
that noted in step 12. See Figure 3-79 for location of adjustment.
High-Frequency
Key in
STEP SIZE
]
and
End Adjustment
16. Adjust All OFFSET for VTP frequency indication 28.000
MHz MHz.
Key in
STEP SIZE
)
and
18. Adjust All GAIN for frequency indication of 28.750
MHz MHz.
19. Repeat steps 15 through 18 until specifications of steps 16 and 18
are achieved.
Low-Frequency
20.
Key in
STEP SIZE
]
End Adjustment
21. Adjust All SHAPING ATTN for indication of 22.000
MHz MHz. See Figure 3-78 for location of adjustment.
22.
Key in
STEP
and
23. Adjust All SHAPING OFFSET for frequency
indication of 21.250 MHz MHz. See Figure 3-78 for
location of adjustment.
24. Repeat steps 21 through 23 until specifications of steps 20 and 23
are achieved.
25. Go back to step 15 and repeat both High-Frequency End and
Lo-Frequency End adjustments until specifications of both
(contained in steps 16, 18, 21, and 23 are achieved.
26.
Key in
STEP SIZE
)
512 and
Center-Frequency
27. frequency indication should be 25.00 MHz MHz. If
Checks
it is not, and specifications of steps 16, 18, 21, and 23 are met,
a malfunction is indicated. The most likely suspects would be
varactor diodes
and
28.
Key in
STEP SIZE
]
612 and
29. frequency indication should be 24.25 MHz MHz. If
it is not, and specifications of steps 16, 18, 21, and 23 are met,
a malfunction is indicated. The most likely suspects would be
varactor diodes
and
30. Set LINE switch to STANDBY.
31. Replace Al1 50 MHz Voltage-Tuned Oscillator in instrument
without extenders and replace screws in cover.
3-132 Adjustments