Cable, CompactFlash and Accessory Specifications
A-12
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
illustrated
in
Figure A-15
.
The
grounding
shunt
is
also
required
to
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 ISDN PRI Connection
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.
You
must
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
Refer
to
“Hardware
Installation
”
on
page 2
‐
1
to
access
the
E1
card
on
the
XSR.
RX In
TX Out
G.703 Balun
Model 460 MC
NIM
-E1-C
OAX-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
Caution:
The cable connecting the E1/ISDN PRI NIM to the balun needs 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.
