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ADJUSTMENTS
5
-
21.
BANDWIDTH FILTER ADJUSTMENTS (SERIAL PREFIX 1909A) (Cont'd)
11. Set
FREQ
SPAN/DIV to 20 kHz, RESOLUTION
BW
to 30
kHz,
and SWEEP TIME/DIV to 10 mSEC.
NOTE
A non
-
metallic tuning tool is required for adjustments on Bandwidth Filter
Assemblies A1 1 and A1
3.
12. Connect crystal shorts (through cover access holes) across A13TPWTP2, A1 lTPl/TP2, and A1 1TP4/
TP5.
NOTE
Keep crystal spike centered during adjustments. The SYM and CTR adjust
-
ments for each crystal
are
interacting.
13. Adjust front
-
panel TUNING control to center bandpass spike (Figure 5
-
7) on the CRT display.
CHECK CENTERING
HERE (SPIKE IS
CRYSTAL RINGING)
CHECK SYMMETRY
HERE (LOW ON SKIRTS)
FIGURE
57.
ADJUSTING CRYSTAL SYMMETRY AND CRYSTAL CENTERING
14. Adjust A13C38 SYM and A13C54 CTR for a centered and symmetrical
bandpass
as
shown
in
Figure
5
-
7.
Adjust
A13C54 CTR for minimum signal amplitude.
15. Remove crystal short from
A13TPl/TP2.