3Com 3C13701 Installation Manual page 38

38 C 4: I
HAPTER NSTALLATION OF THE
R
OUTER
E1 Interface Cable E1 interface cable, which is G.703-compatible, may be 75Ω
unbalanced coax cable or 120Ω balanced twisted pair cable.
unbalanced coax cable
75Ω
■
Figure 30 E1 75Ω unbalanced coax cable
You can also choose to attach both ends with BNC connectors, for extending two 75
unbalanced coax cables.
120Ω balanced twisted pair cable
■
The cable is attached with DB15 (male) connector for the router end, and with RJ45
connector for the network end. See the following figure:
Figure 31 E1 120Ω balanced twisted pair cable
You can also choose to attach both ends with RJ45 connectors, for extending two 120?
balanced twisted pair cables.
E1 interface cable, coax connector assembly, network connector assembly and
75Ω-120Ω converter all are optional.
Impedance Inverter Switch Impedance inverter switch is also available, through
which you can choose the interface impedance value.
Turn on the switch to change the interface impedance to 75Ω, and then you need to
■
connect the 75Ω cable.
Turn on the switch to change the interface impedance to 120Ω, and then you need to
■
connect the 120Ω cable.
Ω