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3-6
Amplifier Setup
The information in Table 3-2 is shown as a graph in Figure 3-2:
Figure 3-2
Frequency versus cable slope
0
-1
-2
-3
-4
-5
-6
-7
-8
-9
-10
-11
-12
Input and Midstage Pads
Install Model JXP-*B pads to attenuate the signal per system design drawings. Generally, this
consists of attenuating excessive input levels. You should pad the input to system levels for
unity gain. Select and install the specified pad in the socket labeled
You can use the midstage pad (
specification. Refer to Section 6, "Operating Tips," for midstage padding information and
recommendations.
Flatness Control
The 8LDR/*/III circuit board includes flatness controls and a fixed cable equalizer for 870 MHz.
This equalizer, plus the contribution of the hybrid gain stages, produces approximately the dB
of slope indicated by the model number (8 dB of tilt with an 8LDR/8/III or 12 dB of tilt with an
8LDR/12/III).
You can adjust the LDR variable resistors and capacitors to flatten the response across the
operating band (marker 1 to marker 4 as illustrated in Figure 3-4). Use C1, C2, R1, and R2 on
the LDR board shown in Figure 3-3 for low-end flatness response (marker 1 to marker 2). The
low-end flatness controls compensate for the roll-off caused by the diplex filters. Adjust C3 and
R3 for a flat response across the mid-band (between marker 2 and 3). Adjust C7, C8, and R8 for
a flat response across the band (marker 1 to marker 4). Adjust C6 for maximum gain at the high
end (marker 3 to marker 4).
C1 produces a peak that is centered just below the lowest forward frequency and varied in
amplitude by R1.
C2 produces a peak that is centered approximately 50 MHz above the lowest forward
frequency and varied in amplitude by R2.
BLE*/* Installation and Operation Manual
Frequency (MHz)
-
) to adjust the gain level and achieve the gain
JXP
MID
SCS-1
SCS-2
SCS-3
SCS-4
SCS-5
SCS-6
SCS-7
SCS-8
SCS-9
SCS-10
-
on the chassis cover.
JXP
IN
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