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The maximum cable length when using the above Draka cable as an example is about 500m, which includes
an allowance for the higher per unit attenuation in the tail cables.
Cables should be marked as required by the tower/shelter owner. Cables should be attached using proper
permanent cable brackets – not temporary plastic cable ties. The minimum bending radius should be
observed (e.g. RFA ½ - 50: 70mm). The cable outer conductor must not be deformed by the cable brackets.
One well-known installation fault is a periodic deformation of the cable causing multiple reflections, signal
distortion and bit errors.
CABLE CONNECTORS
Cable connectors have to be installed to the cable following the manufacturer's instruction strictly and
using the appropriate tools. The connector has to be sealed as recommended to the cable jacket using self
vulcanizing rubber tape or a heat shrink tube with melting glue.
Connectors which are installed improperly may be destroyed by moisture and electrochemical corrosion
within a few months. The connector has to be absolutely dry when installed to the cable and also when the
actual connection between the two connectors is made.
The connector type has to be chosen so that the connection is water-proof without using any external seal
(rubber tape) covering the two connectors. Taped connections are difficult to check for tightness of the
connection between connectors. Rubber taping of the connection is thus not recommended.
GROUNDING
OPERATOR'S OR SHELTER/TOWER OWNER'S GROUNDING INSTRUCTIONS AND LOCAL
REGULATIONS ARE TO BE FOLLOWED.
GROUNDING OUTSIDE
The ODU should be grounded to the tower grounding wire using 16 mm
the grounding terminal screw is M4 (Metric 4 mm). A suitable cable lug (e.g. 16-5.5, tinned copper) should
be used. The connection to the tower grounding wire should be done using an appropriate C-type
connector (Cu-Cu or Cu-Fe).
In case of a roof-top installation, the grounding should use a 16 mm
ground terminal
directly to the main ground bar of the building
to the nearest ground wire of the lightning protection system of the building
to a TV common antenna system ground wire provided that it is minimum 6 mm
to the main grounding bar of the building is verified by measurement,
directly to the main grounding bar of the equipment room where the IDU is installed.
2
or larger copper cable. The size of
2
or larger copper cable from the ODU
2
Cu and continuity
35
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