Furuno FELCOM251, Installation Manual

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2. INSTALLING THE SYSTEM
2-12
2.3.2 Antenna Unit cables
Guidelines
A coaxial cable for connection between the Antenna Unit and Communication Unit is
delivered with the system. If you need a different cable, make sure that the cable
meets the requirements. Preferably choose one of the cable types in Recommended
antenna cables below.
Select a suitable area for installation of the Communication Unit, Antenna Unit and
cradle. Where the cables are exposed to mechanical wear – on deck, through bulk-
heads, etc. - protect the cables with steel pipes. Otherwise, follow standard proce-
dures for cabling in ship installations.
The maximum allowed RF-loss in the antenna cable is 20 dB at 1660 MHz. This is to
ensure the performance of the system.
Recommended Antenna Unit cables
The table below shows recommended cable types and maximum cable lengths for
both FELCOM501 and FELCOM251.
Check in the data sheet from the cable supplier that both the RF-attenuation and the
DC-resistance are kept within the maximum specified values:
• Antenna cable RF-attenuation at 1660 MHz: max. 20 dB incl. connector.
• Antenna cable modem-attenuation at 54 MHz: max. 4 dB.
Antenna cable modem-attenuation at 36 MHz: max. 3 dB.
• Antenna cable loop DC-resistance: max. 1

.
Also ensure that the specified minimum bending radius is respected. If this is not the
case, the loss in the cable will increase. Check the instructions from the cable supplier.
Cable Type Absolute max. length Max. radius when bent
5D-FB 30 m 74.9 mm
8D-FB 50 m 103.6 mm
12D-SFA 100 m 140 mm