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3-10
Amplifier Setup
8
Check the amplifier output tilt by measuring the high band- and low band-edge carriers.
High = channel 116 (745.25 MHz) or channel 136 (865.25 MHz)
Low = channel 2 (55.25 MHz) or channel 3 (61.25 MHz)
If the tilt is less than required, install a higher value input equalizer.
If the tilt is greater than required, install a lower value input equalizer.
If the high value equalizer provides too much tilt and the low value equalizer provides
too little tilt, use the lower value equalizer. Under-equalization is preferred to
over-equalization.
If you use an SCS cable simulator and the design value is changed, you must also adjust the
input pad. For each 1 dB increase in SCS value, 1 dB of loss is introduced at 750 MHz or
1.1 dB of loss at 870 MHz. Therefore, to maintain a proper gain level, it is necessary to
adjust the input pad value as follows:
For each increase in SCS value, decrease the input pad by 1 dB.
For each decrease in SCS value, increase the input pad by 1 dB.
If you replace an SFE with an SCS, reduce the value of the input pad by the value of the
SCS.
9
Measure the output level at the highest frequency.
It should be within 1 dB of the system design level. If it is not, you must adjust the
mid-stage pad (
JXP MID
padding information and recommendations.
Thermal Drive Unit
The TDU senses temperature and controls the Bode board. It is assumed that the cable is
subjected to the same or similar temperature; therefore, you should not use the TDU for
underground installations.
To set-up the TDU:
1
Place the jumper on the TDU (Figure 3-5) to the
the amount of cable for which the TDU compensates at the highest frequency preceding the
BLE*/* station. Low = 0 dB to 15 dB of cable, medium = 15 dB to 30 dB, and high = 30 dB or
more of cable.
Figure 3-5
TDU cable selector
BLE*/* Installation and Operation Manual
) accordingly. Refer to Section 6, "Operating Tips," for mid-stage
Thermal
Medium
Low
High
,
, or
LOW
MEDIUM
HIGH
level
position to specify
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