Enterasys Networks XSR-3020 manual Balun for E1 or PRI NIM Cards, Grounding Shunt for E1 NIM Cards

Cable, CompactFlash and Accessory Specifications

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).

J2 Receive BNC male connector

75-ohm connection to your network

Figure A-14 Balun for E1 or PRI Connection

			J12 Transmit BNC
			male connector
			75-ohm connection
			to your network
				RX
TX			In		NIM
				-
				E1
					-		G
Out				CO
						.
						Model
			AX		703
	BLN
		-
			Balun
				460
			MC					120-ohm

connection to XSR

Grounding Shunt for E1 NIM Cards

If you connect a balun to a 75-ohm line, you will also need to attach a grounding shunt (or terminal strip) to any NIM pins whose RJ-48C connectors utilize the balun. The XSR requires that you use a shunt (shown in Figure A-15), or terminal strip to ground pins 3 and 6 of the RJ-48C interface, which are not needed to complete the connection.

Figure A-15 Sample Grounding Shunt

Caution: The cable connecting the E1/ISDN PRI NIM to the balun requires two more wires to extend the chassis ground to the balun. Cables of this type are often provided by your supplier who can customize them to your needs.

Refer to “Hardware Installation” on page 2-1 to access the E1 card on the XSR.

XSR Getting Started Guide A-13