Enterasys Networks XSR-3150 - Manual (Page 99)

Cable, CompactFlash and Accessory Specifications
XSR Getting Started Guide A-13
Balun for E1 or PRI NIM Cards
Some overseas electrical systems require that you use a balun and grounding shunt when utilizing
an E1 or PRI NIM card on the XSR. A balun is an adapter employed to connect a 75-ohm coaxial
cable pair (2 BNC connectors) to a 120-ohm twisted pair cable (RJ-48C connector).
The balun and its connectors are shown in Figure A-14 . The grounding shunt is also required to
insulate (ground) unused pins of the RJ-48C connector.
To install the balun, attach the 75-ohm coaxial cables to the BNC connectors and a 120-ohm E1/
PRI cable to the RJ-48C port (see below for details).
Figure A-14 Balun for E1 or PRI Connection
RX In
TX Out
G.703 Balun Model 460 MC
NIM
-E1-CO
AX-BLN
J12 Transmit BNC
male connector
75-ohm connection
to your network
120-ohm
connection to XSR
J2 Receive BNC
male connector
75-ohm connection
to your network