Black Box Balun G.703 User manual

1000 Park Drive • Lawrence, PA 15055-1018 • 724-746-5500 • Fax [phone]
© Copyright 1998. Black Box Corporation. All rights reserved.

JUNE 1998
MT243A
MT243C-F
RM243A
G.703 Balun Module Panel Unit
G.703 Balun Module
G.703 Balun Chassis
CUSTOMER SUPPORT INFORMATION
Order toll-free in the U.S. 24 hours, 7 A.M. Monday to midnight Friday: 877-877-BBOX
FREE technical support, 24 hours a day, 7 days a week: Call 724-746-5500 or fax [phone]
Mail order: Black Box Corporation, 1000 Park Drive, Lawrence, PA 15055-1018
Web site: www.blackbox.com • E-mail: [email protected]
Tx
Rx
Tx
Rx
Tx
Rx
Tx
Rx
Tx
Rx
Tx
Rx
Tx
Rx
Tx
Rx
Tx
Rx
Tx
Rx
Tx
Rx
Tx
Rx
Tx
Rx
Tx
Rx
Tx
Rx
Tx
Rx

1
CE NOTICE
CE Notice
The CE symbol indicates that the product is in
compliance with the Electromagnetic Compatibility
(EMC) directive and the Low Voltage Directive (LVD)
of the Union European (EU).
TRADEMARKS USED IN THIS MANUAL
Any trademarks mentioned in this manual are
acknowledged to be the property of the trademark
owners.

2
G.703 MODULES, MODULE PANEL, AND CHASSIS
1. Specifications
Data Rate — 2.048 Mbps
Transmission Line — CCITT G.703 (unstructured)
Connections — 75-ohm: Dual coax BNC connectors,
female (RG59 or 2002 coax); 120-ohm: Shielded RJ-45
jack
Link-to-Data Isolation — 500 volts AC/DC
Operating Temperature — 32 to 122°F (0 to 50°C)
Power Supply — None required
Size — Without handles, 3.5"H x 19"W x 1.9"D
(8.9 x 48.3 x 4.8 cm)

3
CHAPTER 2: Description
2. Description
2.1 Introduction
The G.703 Balun Module Panels match multiple sets of
dual 75-ohm coax connections to multiple 120-ohm
twisted-pair connections. This allows carriers to provide
120-ohm G.703 service to customers retaining 75-ohm
CPE hardware. It also allows carriers who have
standardized on 75-ohm coax to provide 120-ohm
terminations to their customers (in keeping with
European ONP requirements).
Supporting E1 data rates to 2.048 Mbps, the G.703
Balun Module Panels bi-directionally match not only
signal impedance, but also the pulse shapes of the
signals according to the CCITT G.703 standard. The
panels mount in a standard 19-inch rack and are
available with 1 to 16 modules per rack.

4
G.703 MODULES, MODULE PANEL, AND CHASSIS
2.2 Features
• Connects 75-ohm dual coax to 120-ohm twisted
pair.
• Bi-directional signal conversion according to
CCITT G.703.
• Data rates up to 2.048 Mbps.
• Low-profile design.
• Mounts in standard 19-inch rack.
• No AC power or batteries required.
• Strap-selectable modular (RJ-45) pinouts.

5
CHAPTER 3: Configuration
3. Configuration
Each G.703 Balun Module is equipped with four
jumpers that you may use to configure several
grounding options. This chapter shows the jumper
locations and describes their functions.
There are five configuration jumpers on the back of the
Module’s printed circuit board. These jumpers are
labeled JP1, JP2, JP3, JP4, and JP7. Figure 3-1 shows their
positions on the PC board as well as the relative pin
numbers on the jumpers.

6
G.703 MODULES, MODULE PANEL, AND CHASSIS
Figure 3-1. Jumper Location.
Figure 3-2 shows the orientation of the rear interface-
card straps. Note that the strap can either be on posts 1
and 2, or on posts 2 and 3.
Figure 3-2. Possible Positions for the Jumpers.
1 2 3 1 2 3
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
JP4
JP3
JP1
JP2
JP7

7
CHAPTER 3: Configuration
The jumper straps allow you to set shielding and
grounding options. The settings for each jumper strap
are shown in the table below. Following the table are
more detailed explanations of each jumper.
Table 3-1. Strap Summary Table
Strap Function Position 1&2 Position 2&3
JP1 Coax TX Shield & RJ-45 Pin 3 Open* Connected
JP2 Coax TX Shield & RJ-45 Shield Connected* Open
JP3 Coax RX Shield & RJ-45 Shield Connected* Open
JP4 Coax RX Shield & RJ-45 Pin 6 Open* Connected
JP7 RJ-45 Shield & Chassis Ground Connected* Open
*Indicates default setting

8
G.703 MODULES, MODULE PANEL, AND CHASSIS
Jumper JP1: 75-Ohm TX Shield to 120-Ohm TX Pair Shield
(Pin 3)
In the default “Connected” setting, the 75-ohm transmit-
out coaxial shield connects to RJ-45 pin 3, the transmit-
pair shield.
JP1 Setting Description
Position 1 & 2 Not Connected 75-ohm TX shield
not connected to
RJ-45 TX pair shield
(Pin 3)
Position 2 & 3 Connected 75-ohm TX shield
connected to RJ-45
TX pair shield
(Pin 3)

9
CHAPTER 3: Configuration
Jumper JP2: 75-Ohm Shield to 120-Ohm Overall Shield
In the default “Connected” setting, the 75-ohm
transmit-out coaxial shield connects to the RJ-45 overall
foil shield.
JP2 Setting Description
Position 1 & 2 Connected 75-ohm TX shield
connected to the
RJ-45 overall foil
shield
Position 2 & 3 Not Connected 75-ohm TX shield
not connected to
the RJ-45 overall foil
shield

10
G.703 MODULES, MODULE PANEL, AND CHASSIS
Jumper JP3: 75-Ohm RX Shield to 120-Ohm Overall Shield
In the default “Connected” setting, the 75-ohm receive-
in coaxial shield connects to RJ-45 pin 6, the receive-
pair shield.
JP3 Setting Description
Position 1 & 2 Connected 75-ohm RX shield
connected to the
RJ-45 overall foil
shield
Position 2 & 3 Not Connected 75-ohm RX shield
not connected to
the RJ-45 overall foil
shield

11
CHAPTER 3: Configuration
Jumper JP4: 75-Ohm RX Shield to 120-Ohm RX Pair Shield
(Pin 6)
In the default “Connected” setting, the 75-ohm coaxial
shield connects to the RJ-45 overall foil shield.
JP4 Setting Description
Position 1 & 2 Not Connected 75-ohm RX shield
not connected to the
RJ-45 RX pair shield
(Pin 6)
Position 2 & 3 Connected 75-ohm RX shield
connected to the
RJ-45 RX pair shield
(Pin 6)

12
G.703 MODULES, MODULE PANEL, AND CHASSIS
Jumper JP7: RJ-45 Shield to Chassis Ground
In the default “Connected” setting, the RJ-45 overall
shield connects to chassis ground.
JP7 Setting Description
Position 1 & 2 Connected RJ-45 shield connects
to Frame Ground
Position 2 & 3 Not Connected RJ-45 shield does not
connect to Frame
Ground

13
CHAPTER 4: Installation
4. Installation
4.1 The G.703 Balun Chassis
The G.703 Balun Chassis can accommodate up to 16
G.703 Balun Modules. Measuring only 3.5" high, the
Chassis is designed to occupy only 2U in a 19-inch rack.
Sturdy front handles allow the Chassis to be extracted
and transported conveniently.
Figure 4-1. The Chassis.
Rx
Tx
Rx
Tx
Rx
Tx
Rx
Tx
Rx
Tx
Rx
Tx
Rx
Tx
Rx
Tx
Rx
Tx
Rx
Tx
Rx
Tx
Rx
Tx
Rx
Tx
Rx
Tx
Rx
Tx
Rx
Tx

14
G.703 MODULES, MODULE PANEL, AND CHASSIS
4.2 Installing a Module in the Chassis
The Chassis is made up of a 2U-high rack chassis and
individually mountable G.703 Balun Modules. You can
purchase a fully populated 16-port rack (part number
MT243A) or you may purchase individual modules.
Refer to Figure 4-2 as a guide and follow the steps below
to install each additional module into the chassis.
1. Slide the two star washers over the screws on each
end of the mount space.
2. Slide the G.703 Balun Module PC board over the
screws with the BNC connectors facing downward.
Then push the BNC connectors an RJ-45 connector
through the matching slots in the front of the rack
assembly.
3. Slide a plastic spacer over each screw to secure the
PC board.
4. Install the Lexan shield over the spacers.

15
CHAPTER 4: Installation
Figure 4-2. Mounting the Module to the Rack.
5. Secure the Module by connecting a lock washer and
a hex nut on each screw.
Lexan Shield
Modules
Star Washer
(behind the module)
Spacer
Lock Washer
Hex Nut

16
G.703 MODULES, MODULE PANEL, AND CHASSIS
4.3 Connecting the 75-Ohm BNC Ports
The 75-ohm BNC ports on the front of the Chassis are
labeled “TX” (Transmit Data Output) and “RX”
(Receive Data Input). Simply connect the G.703 lines as
follows:
G.703 Network G.703 Balun Module
BNC Connector BNC Connectors
TX................................................RX
RX ..............................................TX
NOTE
The total allowable cable lengths are subject to the
constraints of the ITU/CCITT G.703 recommendation.
However, we recommend a total patch-cable length,
including coaxial and twisted-pair cabling, of no more than
320 feet (200 m).

17
CHAPTER 4: Installation
4.4 Connecting the 120-Ohm RJ-45 Ports
The pin configuration of the 120-ohm twisted-pair port
is shown below:
RJ-45 Pins Function
1 ..................TX Output
2 ..................TX Output
3 ..................TX Shield
4 ..................RX Input
5 ..................RX Input
6 ..................RX Shield
7 ..................No connection
8 ..................No connection
Install the twisted-pair wires by making the following
connections:
G.703 Instrument Module RJ-45 Pin No.
TX Output ..................................4
TX Output ..................................5
TX Shield ....................................3
RX Input......................................1
RX Input......................................2
RX Shield....................................6
NOTE
The total allowable cable lengths are subject to the
constraints of the ITU/CCITT G.703 recommendation.
However, we recommend a total patch cable length,
including coaxial and twisted-pair cabling, of no more than
320 feet (200 m).