Chapter 2 53
Making Adjustments
5. Crystal and LC Bandwidth Filter
LC Alignment
18.Press the following analyzer keys.
BW, 100, kHz
SPAN, 5, MHz
19.Widen all but one of the LC filter poles by shorting A11TP10 and
A11TP11, A11TP12 and A11TP13, and A13TP10 and A13TP11
using the crystal shorts.
CAUTION Use a tool with a nonmetallic body to make the LC dip adjustment.
Shorting components to ground may result in permanent damage to the
bandwidth board assembly.
20.Center the signal on the analyzer display by pressing the following
analyzer keys.
PEAK SEARCH
MKR FCTN, MK TRACK ON OFF (ON)
21.Adjust A13C47 LC dip for a minimum signal amplitude.
22.Move the short from A13TP10 and A13TP11 to A13TP12 and
A13TP13, then adjust A13C17 LC dip for a minimum signal
amplitude.
23.Move the short from A11TP10 and A11TP11 to A13TP10 and
A13TP11, then adjust A11C17 LC dip for a minimum signal
amplitude.
24.Move the short from A11TP12 and A11TP13 to A11TP10 and
A11TP11, then adjust A11C47 LC dip for a minimum signal
amplitude.
LC Centering
Note that the center frequency of the 100 kHz bandwidth is referenced
to the 30 kHz bandwidth. During this procedure it is advisable to
switch to the 30 kHz bandwidth occasionally and recenter it using
PEAK SEARCH, MARKER → CF.
25.Short A11TP10 and A11TP11, A11TP12 and A11TP13, and
A13TP10 and A13TP11 using the crystal shorts used in the crystal
alignment section. Press the following analyzer keys.
BW, 30, kHz
SPAN, 200, kHz
MKR FCTN, MK TRACK ON OFF (OFF)
BW, 100, kHz
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