3Com 5000 Series Installation Manual page 50

3Com Router 5000 Family
Installation Guide
Figure 4-32 E1 120Ω balanced twisted pair cable
Note:
You can also choose to attach both ends with RJ45 connectors, for extending two 120
balanced twisted pair cables.
Note:
E1 interface cable, coax connector assembly, network connector assembly and
75Ω-120Ω converter all are optional.
3) 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.
4) Connecting E1 interface cable
Caution:
Examine the interface mark before connection to avoid cable mis-insertion and
router damage.
When the E1 interface cable is routed outdoors, you need use the special lightning
protection unit at the input end to prevent possible damage.
3Com Corporation
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Chapter 4 Installation of the Router