3Com 5000 Series Installation Manual page 51

3Com Router 5000 Family
Installation Guide
Step 1: Check the E1 cable type and choose correct impedance value of the E1
interface through the inverter switch.
Step 2: Insert the DB15 connector into the E1 interface of the router.
Step 3: Connect the other end to the right network devices.
For 75Ω unbalanced coax cable
Connect the cable in this way:
If you choose only a single BNC connector, just connect the BNC connector to the peer
device.
If you choose two BNC connectors (for extending E1 interface cables), connect the
BNC connector of the 75Ω unbalanced coax cable to a coax connector assembly,
which is connected to a 75Ω E1 trunk cable. The 75Ω E1 trunk cable is then connected
to the peer device.
Caution:
Connect the Tx end of the E1 interface cable to the Rx end of the peer unit, and Rx end
of the E1 interface cable to the Tx end of the peer unit.
75Ω unbalanced
Figure 4-33 Extending two E1 75Ω unbalanced coax cables
If the peer device provides the 120Ω interface, you need to use 75Ω−120Ω converter or
120Ω cable.
For 120Ω balanced twisted pair cable
Connect the cable in this way:
If you choose only a single RJ45 connector, just connect the RJ45 connector to the
peer device.
If you choose two RJ45 connectors (for extending E1 interface cables), connect the RJ
connector of the 120Ω balanced twisted pair cable to a network connector assembly,
DB-15
BNC connector
Coax connector
coax cable
assembly
3Com Corporation
Chapter 4 Installation of the Router
BNC
connector
75Ω E1
trunk cable
4-24
DDN