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7. 3 MHz Bandwidth Filter Adjustments
3-74 Adjustments
10. Adjust A4A7C15 CTR for minimum amplitude of signal peak.
Adjust A4A7C14 SYM for best symmetry. Repeat adjustments to
ensure that the signal is nulled and adjusted for best symmetry.
See Figure 3-38 for location of adjustments.
11. Remove crystal filter bypass network near C23 SYM.
12. Adjust A4A7C24 CTR for minimum amplitude of signal peak.
Adjust A4A7C23 SYM for best symmetry of signal. Repeat
adjustments to ensure that signal is nulled and adjusted for best
symmetry. See Figure 3-38 for location of adjustments.
13. Remove crystal filter bypass network near C32 SYM.
14. Adjust A4A7C33 CTR for minimum amplitude of signal peak.
Adjust A4A7C32 SYM for best symmetry of signal. Repeat
adjustments to ensure that signal is nulled and adjusted for best
symmetry. See Figure 3-38 for location of adjustments.
15. Remove crystal filter bypass network near C41 SYM.
16. Adjust A4A7C42 CTR for minimum amplitude of signal peak.
Adjust A4A7C41 SYM for best symmetry of signal. Repeat
adjustments to ensure that the signal is nulled and adjusted for
best symmetry. See Figure 3-38 for location of adjustments.
17. Signal should be centered on center graticule line on CRT display.
If signal is not centered, go back to step 3 and repeat adjustments
of each filter stage.
Filter Peak Adjust
18. Press
].
PRESET
19. Key in
20 ms,
]
TIME
-20 dBm.
[
)
R E F E R E N C E
L E V E L
20. Set the frequency synthesizer for 21.400 MHz at an amplitude
level of -25.0 dBm.
21. Disconnect cable 97 (white/violet) from A4A8Jl and connect
output of the frequency synthesizer to A4A8Jl using BNC to SMB
snap-on cable.
22. Set the oscilloscope following settings:
Channel 1
amplitude . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.005 V/div
time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...0.2 psldiv
mag x . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 (vertical) .
coupling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..ac
probe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1O:l
Channel 2
amplitude . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . O.O05V/div
coupling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ac
probe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1O:l
23. Connect oscilloscope Channel 1 probe to A4A7TP7 (left side of
SYM).
24. Adjust frequency synthesizer output frequency to peak Channel 1
display.
0 Hz, CREs] 10 Hz,
[
)
FREQUENCY SPAN
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