3Com 3C13755-US - Router 5642 Installation Manual page 43

Connecting the 75-ohm Unbalanced Coaxial Cable
The 75-ohm unbalanced coaxial cable is shown in Figure 42.
Figure 42 E1-75-Ohm Unbalanced Coaxial Cable
Enlarged A side
You can select a pair of coaxial connectors with a BNC receptacle at both ends
that connect two 75-ohm unbalanced coaxial cables with BNC connectors. The
coaxial connectors are used in the extension connection with E1 75-ohm
unbalanced coaxial cable
At the router end, the cable has a DB-15 (male) connector. At the network end,
the connector is an RJ-45.
To connect the 75-ohm unbalanced coaxial cable:
1 Power off the router.
2 Check the type of E1 cable, and set the DIP switches of the 2-port E1/CE1/PRI MIM
correctly.
3 Plug the DB-15 connector of E1 cable into the E1 interface of the module.
4 Connect the other end of E1 cable to the corresponding network device:
If you do not need to extend the E1 cable, connect the BNC connector of the
75-ohm unbalanced coaxial cable to the remote device directly.
If you need to extend the E1 cable, connect the BNC connector of 75-ohm
unbalanced coaxial cable to a coaxial connector, then connect the other end of the
coaxial connector to the remote device through the 75-ohm E1 trunk cable. Make
sure that the end of the E1 coaxial cable that is marked TX is connected to the
cable of the remote device marked RX and that the end of the E1 coaxial cable
marked RX is connected to the cable of the remote device marked TX. See
Figure 43.
Figure 43 Extension Connection of an E1 75-Ohm Unbalanced Coaxial Cable
DB-15
Router
75-ohm non-balanced coaxial cable
DB15 Male
Magnetic core
Hot-shrinkable tube
BNC
Coaxial connector
75-ohm E1 trunk cable
2-Port E1/CE1/PRI MIM
BNC connector
Label
BNC
Network
devices,
such as
leased line
41