General Instrument STARLINE MB-750D-H User manual

Dual-Output Amplifier
Model MB-750D-H
Model MB-750D-H/40
Installation Manual
ASSEMBLED IN MEXICO
General Instrument Corporation
GI Communications Division
Hatboro, Pa. 19040
20 dB
FWD/
RET
X0-36
20A
JXP
FWD
IN
FORWARD
EQUALIZER
JXP
JXP
JXP
FWD
INTR
FWD
OUT
FWD
OUT
MAN
ACB
OFF
L
H
X0-36
MB-750D-H
20 dB
PORT
2
20 dB
PORT3&4
RET
IN
JXP
X0-36
SPLIT
JXP
RET
OUT
AUTOMATIC CONTROL
BOARD
RETURN
EQUALIZER
SEE- *
RESPONSE
CORRECTION
MDR
EQ- *
IN
3
XO-36
4
DUAL HYBRID
POWER DOUBLING
MINI-BRIDGER
2
General Instrument
GI
EQUALIZER
MDR-750/10
C80
C81
C82
SEE-* EQUAL.
FORWARD CABLE
General Instrument Corporation
Hatboro, Pa. 19040
POWER SUPPLY
DC VOLTAGE
ADJUST
ASSEMBLED IN MEXICO
REGULATED DC VOLTAGE
DC (-) DC (+)POWER
GROUND
FUSE
VOLTS (RMS)
MAY BE PRESENT UNDER COVER
VOLTAGES IN EXCESS OF 150 VOLTS
CAUTION
MPPS AC
AC
ARRESTOR
SURGE
Jerrold Communications
AC LINE
VOLTAGE
GI General Instrument
Jerrold

Copyright © 1995 by General Instrument Corporation.
All rights reserved.
No part of this publication may be reproduced in any form or by anymeans or used to make any derivative work (such as translation,
transformation or adaptation) without written permission from General Instrument.
General Instrument reserves the right to revise this publication and to make changes in content from time to time without obligation on the part of
General Instrument to provide notification of such revision or change.
General Instrument provides this guide without warranty of any kind, either implied or expressed, including, but not limited, to the implied warranties
of merchantability and fitness for a particular purpose. General Instrument may make improvements or changes in the product(s) described in this
manual at any time.
Cableoptics and STARLINE are registered trademarks of General Instrument Corporation.

MB-750D-H and MB-750D-H/40 Mini-Bridger Installation Manual
Contents
Introduction .......................................................................................................................1
Using This Manual....................................................................................................................1
Related Documentation............................................................................................................1
If You Need Help.......................................................................................................................2
Calling for Repairs ....................................................................................................................2
Overview ............................................................................................................................3
Product Description ..................................................................................................................3
Optional Components and Accessories....................................................................................4
Assemblies and Modules..........................................................................................................5
Housing Model MB-HSG/60...............................................................................................5
Model MPPS Power Pack ..................................................................................................5
Forward Amplifier...............................................................................................................7
Models MBD-SPLT and MBD-DC......................................................................................8
Return Signal Path.............................................................................................................8
Forward Output Level Control............................................................................................9
Power Control Options.......................................................................................................9
Automatic Control Board....................................................................................................9
Preinstallation Procedures .............................................................................................11
Configuring the MB-750D-H*..................................................................................................11
Forward Equalizer, Model EQ-750-* ................................................................................11
Output Passives...............................................................................................................13
Power Control Options.....................................................................................................14
Automatic Control Board Option, Model MB-ACB/* .........................................................14
Two-Way Option ..............................................................................................................14
Bench Powering the MB-750S-H/40/E Amplifier..............................................................15
Installing DF1-SS/40 Diplex Filters...................................................................................15
Sweep Response and Gain Testing.................................................................................17
Manual Thermal Gain Control..........................................................................................18
Flatness............................................................................................................................18
Operational Gain..............................................................................................................19
Automatic Level Control...................................................................................................20

ii Contents
MB-750D-H and MB-750D-H/40 Mini-Bridger Installation Manual
Field Installation ..............................................................................................................21
Mechanical Installation...........................................................................................................21
Housing Connections.......................................................................................................21
Mounting the Housing......................................................................................................21
Power-up................................................................................................................................22
Balancing the Amplifier...........................................................................................................22
Manual Thermal Gain Control................................................................................................23
Automatic Level Control .........................................................................................................23
Closing the Housing ...............................................................................................................24
Specifications ..................................................................................................................25
Amplifier .................................................................................................................................25
Automatic Control Board, MB-ACB/∗.....................................................................................26
Return Amplifier Kit, RA-Kit/40L.............................................................................................26
Diplex Filters, DF1-SS/40 and DF1-SS..................................................................................26
List of Figures
Figure 1 MB-750D-H and MB-750D-H/40 Mini-Bridger block diagram ..................................4
Figure 2 Mini-Bridger amplifier module, showing location of accessories..............................5
Figure 3 Block diagram of MPPS power pack........................................................................6
Figure 4 MPPS Power pack ...................................................................................................7
Figure 5 Forward amplifier module.........................................................................................8
Figure 6 Tilt versus cable.....................................................................................................13
Figure 7 Model MBD-DC output directional coupler.............................................................13
Figure 8 Restoring impedance match, port 3.......................................................................15
Figure 9 Restoring impedance match, port 4.......................................................................16
Figure 10 Typical test equipment and connections..............................................................17
Figure 11 MDR-750/10 Board ..............................................................................................19
Figure 12 Effect of flatness controls.....................................................................................19
Figure 13 Pin connector .......................................................................................................21
Figure 11 MB-HSG/60 Housing............................................................................................22

MB-750D-H and MB-750D-H/40 Installation Manual
Section 1
Introduction
The General Instrument STARLINE®Mini-Bridgers, models MB-750D-H and MB-750D-H/40
are versatile amplifiers used in modern television distribution systems for amplification of
standard National Television Sytem Committee (NTSC) television carriers as well as
high-definition digital channels. The MB-750D-H and MB-750D-H/40 amplify conventional
signals carried in the bandpass between 50 MHz and 550 MHz as well as high-definition digital
television signals carried in the bandpass between 550 MHz and 750 MHz. These digital
carriers have their relative amplitude set at the headend and normally operate 10 dB below
standard NTSC television channels.
Using This Manual
This manual provides instructions for the following tasks necessary to install, configure, and
operate the MB-750D-H and MB-750D-H/40 mini-bridgers:
Section 1 Provides a brief review of the function of the product in a distribution system. Identifies the
information contained in this manual, lists related documentation, and gives the helpline
telephone number.
Section 2 Provides a detailed description of the various components used in the amplifier. It also
provides instructions on proper installation of all options and subassemblies.
Section 3 Describes methods of bench alignment, testing, and configuration of the unit prior to
installing it in the system.
Section 4 Describes the installation and field alignment procedures required to place the unit into
service.
Appendix A Lists the applicable specifications for the amplifier and options.
This installation manual assumes that all channels are standard NTSC analog channels. Refer
to catalog specifications or Appendix A, Specifications, in this document for further details
pertaining to signal levels of digital channels above 550 MHz.
The asterisk (*) indicates that there are several versions or model numbers, and the information
applies to all models. When the information applies to a specific model, the full model number is
given.
Related Documentation
This installation manual is complete and you should not require any additional documentation
to install, test or operate the MB-750D-H and MB-750D-H/40 mini-bridgers.

2Introduction
MB-750D-H and MB-750D-H/40 Installation Manual
If You Need Help
If you need assistance while working with the MB-750D-H or MB-750D-H/40, call the General
Instrument Technical Response Center at 1-800-537-7653. The Technical Response Center is
open 8:00 am to 6:00 pm Eastern Standard Time, Monday through Friday. When the Technical
Response Center is closed, emergency service only is available on a call-back basis.
When contacting the Technical Response Center from outside the United States, please use our
main switchboard number, 1-215-674-4800. After business hours, please use 1-215-581-9637.
Calling for Repairs
If repair is necessary, call the General Instrument Repair Facility at 1-800-642-0442 for a
Return for Service Authorization (RSA) number before sending the unit. The RSA number must
be prominently displayed on all equipment cartons. The Repair Facility is open 7:00 am to
4:00 pm Pacific Standard Time, Monday through Friday.
If calling from outside the United States, dial your appropriate international access code, then
dial 52-631-34000, to contact the Repair Facility.
When shipping equipment for repair, follow these steps:
Pack the unit securely.
Enclose a note describing the exact problem.
Enclose a copy of the invoice that verifies the warranty status.
Ship the unit PRE-PAID to the following address:
GI Communications
c/o Fritz Company
1451-1 Mariposa Industrial Drive
Nogales, AZ 85621
Attn: RSA #___________

MB-750D-H and MB-750D-H/40 Installation Manual
Section 2
Overview
Product Description
The model MB-750D-H and MB-750D-H/40 Mini-Bridgers are dual output, high gain,
three-stage hybrid amplifiers designed to drive both a limited cascade as well as a local
distribution system. These amplifiers provide 110-channel capability utilizing a forward
bandpass of 50 to 750 MHz and a return path of either 5 to 30 MHz for model MB-750D-H and
5 to 40 MHz for model MB-750D-H/40. The high gain feature — 35 dB operational — makes the
amplifiers suitable for drop-in replacement of trunk amplifiers that were originally spaced for
22 dB at 300 MHz. Use of the mini-bridgers eliminates the need for intermediate amplifiers
normally required to modify a “tree-and-branch” system into a “fiber-to-the-feeder” architecture.
The attenuation of coaxial cable as used in CATV systems changes with variations in
temperature. To assist in compensating for these changes, the MB-750D-H and MB-750D-H/40
include manual thermal gain compensation. The degree of thermal compensation is selectable
by a plug-in jumper and can be set to 0, 17 or 26 dB of cable. Gain control through automatic
temperature compensation is an available option.
The basic amplifier is shipped in housing model MB-HSG/60 and includes all necessary
components for a fully functional one-way amplifier, with the exception of the forward cable
equalizer, model EQ-750-*.
The block diagram in Figure 1 shows the functional interconnections of all stages in both
amplifiers.

4Overview
MB-750D-H and MB-750D-H/40 Installation Manual
Figure 1
MB-750D-H and MB-750D-H/40 Mini-Bridger block diagram
Optional Components and Accessories
The following table provides a list of optional equipment that can be selected to work in
conjunction with the mini-bridgers to better satisfy individual system requirements. The table
also provides a brief description and basic function of each item to assist the user in the selection
process. All optional equipment can be installed at field locations by qualified technicians.
Figure 2 is provided to show the location of common accessories and components.
Table 1
Summary of optional components available with the MB-750D-H* Mini-Bridger
Model Number Description
MB-ACB/* Auto control board module. Provides automatic output level control.
RA-Kit/40L Return amplifier kit. Implements two-way service.
EQP1-1 Equalizer circuit board. Used for test purposes, or when a zero value equalizer is
required.
EQ-750-* Forward cable equalizer. Compensates for cable attenuation from 2 through 22 dB in
2 dB steps.
SX5B Circuit breaker. Powers output port and provides protection against overcurrent.
SX7F/SX10FA Feederline fuse. Powers output port and provides protection against overcurrent.
XO-36 Surge arrestor. Used with a circuit breaker or fuse to provide additional surge protection.
MBD-SPLT or
MBD-DC Output passives. Can be installed in place of the supplied MBD-JMP jumper to activate
the third output of the amplifier.
MDR-750/FLT Flatness control board. Used to replace the furnished MDR-750/10 interstage equalizer
and flatness board when flatness without equalization is required.

Overview 5
MB-750D-H and MB-750D-H/40 Installation Manual
Figure 2
Mini-Bridger amplifier module, showing location of accessories
Assemblies and Modules
This section describes each of the major components and subassemblies associated with the
MB-750D-H and MB-750D-H/40 Mini-Bridgers.
Housing Model MB-HSG/60
The purpose of the housing is to protect the electronics from the elements and serve as a radiator
to dissipate the internally generated heat. While the amplifiers are shipped with the model
MB-HSG/60 housing, they can also be installed in an existing XLE-HSG housing.
Both housings can be strand mounted by using the included clamp and bolt assemblies, or
surface mounted by using suitable auxiliary brackets. In addition, two 1/4 × 20 threaded holes
are provided in the lower housing half for pedestal or surface mounting.
Each housing is equipped with a combination woven-wire/silicone-rubber gasket between the
body and the cover for efficient ground continuity, RF shielding and weather protection. The
input and output ports are protected by factory inserted plastic cap plugs which are discarded
when the cable connectors are installed.
Model MPPS Power Pack
The model MPPS power pack is mounted within the cover of the amplifier housing. It provides
24 Vdc output at 2.0 amperes maximum over an ac input voltage range from 38 Vac to 60 Vac
rms. The waveshape of the input voltage may be either a squarewave or a sinewave. The surge
arrestor and the EMI filter protect the power pack and amplifier from transient spikes.
Additional surge protection is built into the power pack by a fast acting zener diode. A 5 amp
fast-blow fuse in the ac line offers further protection in case of catastrophic power pack failure.

6Overview
MB-750D-H and MB-750D-H/40 Installation Manual
The pre-regulator is a fixed frequency switching regulator that will present a near perfect power
factor to the input line. It includes overvoltage as well as overcurrent protection. The precision
output regulator is also protected against overcurrent and short circuits, thus providing a precise
output voltage. If a short circuit is detected, the power supply shuts down and the regulator
initiates a sequence of line test pulses at approximately one-half second intervals. The regulator
will continue these pulses for the duration of the short circuit but will return to normal operation
when the fault is cleared.
Figure 3 illustrates a block diagram of the MPPS power pack.
Figure 3
Block diagram of MPPS power pack