3Com 3C13755-US - Router 5642 Installation Manual page 28

26 C 2: I
HAPTER NTRODUCING
R 5012 SIC
OUTER S
Figure 25 Extended Connection of the E1 75-Ohm Non-balanced Coaxial Cable
DB-15
Router
75-ohm non-balanced coaxial cable
To connect the cable:
1 Power off the router.
2 Check the type of E1 cable and correctly set the DIP switch (the default) setting of
the E1 interface impedance is 75-ohm).
3 Connect the DB-15 connector of the E1 cable to the 1-Port Fractional E1 SIC
interface card.
4 Connect the other end of the E1 cable to the corresponding network device.
If you do not need to extend the E1 cable, directly connect the BNC connector
of the 75-ohm non-balanced coaxial cable to the remote device.
If you need to extend the E1 cable, connect the BNC connector of the 75-ohm
non-balanced coaxial cable to the coaxial connector and the other end of the
coaxial connector to the remote network device using a 75-ohm E1 trunk
cable. See Figure 25.
The wire marked TX in the E1 cable should be connected with the peer wire
marked RX and the wire marked RX should be connected with the peer wire
marked TX.
If the remote device has a 120-ohm interface, you should use a
75-ohm-to-120-ohm adapter or use a 120-ohm cable.
Connecting the Twisted Pair Cable
Figure 26 illustrates the 120-ohm balanced twisted pair cable E1 G.703 120-ohm
Figure 26 Balanced Twisted Pair Cable
Enlarged A side
The 120-ohm balanced twisted pair cable connects the 1-Port Fractional E1 SIC
interface card with the DB-15 connector and, on the network end, with the RJ-45
connector.
BNC
Coaxial connector
75-ohm E1 trunk cable
DB15
BNC
Network
devices,
such as
leased line
RJ-45
Enlarged B side