3Com MSR 20, MSR 30, MSR 50 manual Cable

MIM-IMA-4E1/MIM-IMA-8E1 Module 133

75-ohm 4E1 conversion cable contains eight coaxial cables, and the 120-ohm 4E1 conversion cable contains four twisted pairs.

The MIM-IMA-8E1 module provides eight E1 ports and adopts a 120-ohm or a

75-ohm 8E1 conversion cable. The two types of 8E1 conversion cables look similar. Both of them have a DB68 connector at one end for connecting the router. However, the 75-ohm 8E1 conversion cable contains 16 coaxial cables and the 120-ohm 8E1 conversion cable contains eight twisted pairs, as shown in the following figures:

Figure 150 120-ohm 8E1 conversion cable

Figure 151 75-ohm 8E1 conversion cable

Connecting the Interface Follow these steps to connect the MIM-IMA-4E1/ MIM-IMA-8E1 interface cable.

Cable

Step 1: Choose a 4E1/8E1 conversion cable appropriate to the interface type of the peer device to be connected.

■If the interface impedance of the peer device is 75 ohm, use a 75-ohm 4E1/8E1 conversion cable.

■If the interface impedance of the peer device is 120 ohm, use a 120-ohm 4E1/8E1 conversion cable.