Installation
Block Up Converter Systems 6700/6900 series User Guide 33
DC loop resistance specification
The maximum DC loop resistance is determined by the DC
power drawn by a BUC and its minimum operating input
voltage. Some BUCs are not powered via the cable, so the DC
loop resistance of the IF cable is not a consideration for such
BUC installations.
Cable screening specification
Cable screening is derived from regulatory requirements
related to the radiation of spurious signals from the antenna.
Screening is more critical if the BUC is co-located with other
radio transmitting equipment, for example, mobile-phone
towers.
Cable lengths
Table 10 shows the maximum lengths of different types of
cables to ensure the 20 dB loss recommendation is not
exceeded. The cable lengths are shown in metres and feet.
CAUTION
To ensure correct operation, the DC loop
resistance figure must not be exceeded.
Table 10: Cable lengths resulting in a 20 dB loss
Frequency
(MHz)
RG223
(m (ft))
Belden 9914
(m (ft))
Belden 9913F
(m (ft))
Times
Microwave
LMR-400
(m (ft))
950 43 (141) 104 (341) 125 (410) 150 (492)
1450 34 (111) 81 (266) 99 (325) 120 (394)
1700 31 (102) 74 (243) 91 (299) 111 (364)
1750 31 (102) 73 (240) 89 (292) 109 (358)
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