UBS Axcera HU5000BTD 5000-Watt UHF Digital Transmitter User Manual Title Page Vol 2

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Instruction Manual
Innovator HXB Series
Digital UHF
Solid State
Transmitter
Volume 2
UHF Amplifier Cabinet
Axcera , LLC
103 Freedom Drive • P.O. Box 525 • Lawrence, PA 15055-0525 USA
1-724-873-8100 • FAX: 1-724-873-8105
www.axcera.com • service@axcera.com
RESTRICTIONS ON USE, DUPLICATION OR DISCLOSURE
OF PROPRIETARY INFORMATION
This document contains information proprietary to Axcera, to its affiliates or to a third party to
which Axcera may have a legal obligation to protect such information from unauthorized
disclosure, use or duplication. Any disclosure, use or duplication of this document or any of the
information herein for other than the specific purpose for which it was disclosed by Axcera is
expressly prohibited, except as Axcera may otherwise agree in writing. Recipient by accepting this
document agrees to the above stated conditional use of this document and this information
disclosed herein.
Copyright © 2009, Axcera
Innovator® HXB Series, Digital,
UHF Transmitter
Table of Contents
TABLE OF CONTENTS
CHAPTER 1: INTRODUCTION
SECTION
PAGE
1.1: Manual Overview .................................................................................1-1
1.2: Safety.................................................................................................1-1
1.3: Assembly Designators ..........................................................................1-2
1.4: Material Return Procedure.....................................................................1-2
1.5: Limited One-Year Warranty for Axcera Products ......................................1-3
CHAPTER 2: UHF AMPLIFIER CABINET
2.1: Cabinet Overview.................................................................................2-1
2.2: Description of the UHF Amplifier Cabinet ................................................2-2
2.2.1: 5 kW Amplifier Cabinet with 8 Amplifier Assemblies ........................2-3
2.2.2: 3.7 kW Amplifier Cabinet with 6 Amplifier Assemblies .....................2-3
2.2.3: 2.5 kW Amplifier Cabinet with 4 Amplifier Assemblies .....................2-3
2.2.4: 1.8 kW Amplifier Cabinet with 3 Amplifier Assemblies .....................2-4
2.3: Description of the UHF Amplifier Tray .....................................................2-7
2.3.1: Description of the 8 Way Combiner Assembly (5 kW) .....................2-7
2.3.1.1: Description of the 6 Way Combiner Assembly (3.7 kW)..........2-9
2.3.1.2: Description of the 4 Way Combiner Assembly (2.5 kW)..........2-9
2.3.1.3: Description of the 3 Way Combiner Assembly (1.8 kW)..........2-9
2.3.2: Removal of an Amplifier Tray Assembly.........................................2-9
2.3.3: Amplifier Cabinet Power Supply Assemblies ................................. 2-10
2.3.4: Control and Monitoring .............................................................. 2-10
2.3.5: Cabinet Cooling ........................................................................ 2-10
2.4: Cabinet Controller Assembly................................................................ 2-12
2.4.1: Controller Connections to the Transmitter’s System Controller ....... 2-13
2.4.2: Controller Connections to the Amplifier Cabinet Components ......... 2-14
2.4.2.1: Power Amplifiers.............................................................. 2-14
2.4.2.2: High Power Voltage Supply Controllers............................... 2-14
2.4.2.3: Low Power Voltage Supply and AC Line Monitoring .............. 2-15
2.4.2.4: Air Temperature and Amplifier Temperature Monitoring ....... 2-15
2.4.2.5: RF Power Monitoring ........................................................ 2-15
2.4.2.6: Reject Load Monitoring..................................................... 2-16
2.4.3: Cabinet Controller Settings ........................................................ 2-16
2.4.4: Cooling Blower Control .............................................................. 2-17
2.4.5: Cabinet Controller Problem Resolution Guide ............................... 2-17
2.5: Functional Description of Amplifier Cabinet ........................................... 2-19
2.5.1: Signal Path............................................................................... 2-19
2.5.2: Test Signal Evaluation ............................................................... 2-19
2.5.3: Regulation of Transmitter Output Power ...................................... 2-19
2.5.4: Fault Protection Circuitry ........................................................... 2-19
2.5.5: Capture of Operating Values in the Amplifiers .............................. 2-20
2.5.6: Amplifier Cabinet Connections .................................................... 2-20
2.6: Service ............................................................................................. 2-21
2.6.1: Safety Information.................................................................... 2-21
2.6.1.1: Labeling of Dangerous Substances .................................... 2-21
2.6.2: Test point Evaluation................................................................. 2-21
2.6.3: Display of Operating Values ....................................................... 2-21
2.7: Exchange of an Amplifier Module ......................................................... 2-22
Volume 2, Rev. 0
November 16, 2009
Innovator® HXB Series, Digital,
UHF Transmitter
Table of Contents
TABLE OF CONTENTS (continued)
CHAPTER 3: UHF AMPLIFIER TRAY ASSEMBLY & CABINET ASSEMBLIES
CIRCUIT DESCRIPTIONS
SECTION
PAGE
3.1: Amplifier Overview ...............................................................................3-1
3.2: Design of the UHF Amplifier Tray ...........................................................3-2
3.2.1: Capture of Test Values in the UHF Amplifier Tray............................3-5
3.2.2: Functional Description of the Boards in the Amplifier Assembly ........3-6
3.2.2.1: Phase/Gain Board ..............................................................3-6
3.2.2.2: Dual BLF871 Amplifier Module Assembly ..............................3-6
3.2.2.3: Coupler Board ...................................................................3-6
3.2.2.4: 4 Way Splitter Board ..........................................................3-7
3.2.2.5: UHF Broadband Pallet Board, BLF878...................................3-8
3.2.2.6: 4 Way Combiner Board ......................................................3-8
3.2.2.7: FET Switch/Metering Board .................................................3-9
3.2.2.7.1: Operating voltages for the Amplifier Boards................3-9
3.2.2.8: Amplifier Control Board ......................................................3-9
3.2.2.8.1: Schematic Drawing 1311684 Page 1........................ 3-10
3.2.2.8.2: Schematic Page 2 .................................................. 3-11
3.2.2.8.3: Schematic Page 3 .................................................. 3-11
3.2.2.8.4: Schematic Page 4 .................................................. 3-11
3.2.2.8.5: Schematic Page 5 .................................................. 3-12
3.3: Troubleshooting and Repair of the Amplifier.......................................... 3-12
3.3.1: Safety Information.................................................................... 3-12
3.3.2: Troubleshooting........................................................................ 3-12
3.3.2.1: Front Panel LEDs ............................................................. 3-12
3.3.2.2: Polling Fault Indications.................................................... 3-13
3.4: Exchanging Amplifiers ........................................................................ 3-13
3.4.1: Exchange of a Module ............................................................... 3-13
3.4.2: Mounting a New Module............................................................. 3-13
3.4.3: Final Steps ............................................................................... 3-13
3.4.4: External Connections to Amplifier Assembly................................. 3-14
3.5: Power Supply Assembly ...................................................................... 3-14
3.5.1: Overview of the +48V Power Supply Unit .................................... 3-15
3.5.2: Description of SCR Controllers.................................................... 3-15
3.5.3: Description of the Step Down Transformers ................................. 3-15
3.5.4: Description of the Linear Power Supply Assemblies....................... 3-15
3.5.4.1: Description of the Power Supply Monitoring Board............... 3-16
3.6: Full Amplifier Cabinet Controller Board ................................................. 3-20
3.6.1: Schematic Drawing 1307524 Page 1 ........................................... 3-20
3.6.2: Schematic Drawing Page 2......................................................... 3-20
3.6.3: Schematic Drawing Page 3......................................................... 3-21
3.6.4: Schematic Drawing Page 4......................................................... 3-21
3.6.5: Schematic Drawing Page 5......................................................... 3-21
3.7: Half Amplifier Cabinet Controller Board................................................. 3-24
3.7.1: Schematic Drawing 1307841 Page 1 ........................................... 3-24
3.7.2: Schematic Drawing Page 2......................................................... 3-24
3.7.3: Schematic Drawing Page 3......................................................... 3-25
3.7.4: Schematic Drawing Page 4......................................................... 3-25
3.7.5: Schematic Drawing Page 5......................................................... 3-25
3.8: Temperature Sensor Board ................................................................. 3-26
Volume 2, Rev. 0
ii
November 16, 2009
Innovator® HXB Series, Digital,
UHF Transmitter
Table of Contents
TABLE OF CONTENTS (continued)
SECTION
PAGE
3.9: Serial Loop-Thru Board ....................................................................... 3-26
3.10: Load Regulator Assembly .................................................................. 3-26
3.10.1: Load Regulator Board .............................................................. 3-26
APPENDICES
APPENDIX A: RF Amplifier Cabinet Assembly, HXB Series
Drawings and Parts Lists
APPENDIX B: UHF Amplifier Tray Assembly, HXB Series
Drawings and Parts Lists
APPENDIX C: +48 VDC Power Supply Assemblies, Top and Bottom
Drawings and Parts Lists
Volume 2, Rev. 0
iii
November 16, 2009
Innovator® HXB Series, Digital,
UHF Transmitter
Table of Contents
LIST OF FIGURES
FIGURE
1-1
PAGE
Marker Identification Drawing..........................................................1-2
2-1
2-2
2-3
2-4
2-5
2-6
2-7
2-8
2-9
2-10
2-11
2-12
2-13
Typical UHF Amplifier Cabinet (Front View) .......................................2-1
Block Diagram Typical UHF Amplifier Cabinet 8 Way (5 kW)................2-2
Block Diagram Typical UHF Amplifier Cabinet 4 Way (2.5 kW).............2-4
Components in the Amplifier Cabinet................................................2-5
Block Diagram Typical UHF Amplifier Tray Assembly ..........................2-6
Block Diagram Typical 8 Way UHF Combiner Assembly.......................2-8
Air Flow in the Amplifier Cabinet .................................................... 2-11
Full Cabinet Controller Assembly.................................................... 2-12
Half Cabinet Controller Assembly ................................................... 2-12
Amplifier Cabinet Connections ....................................................... 2-20
Labeling of Toxic Substances in Drawings ....................................... 2-21
Location and Assignment of the Circuit Breakers and LEDs ............... 2-22
Amplifier Tray Lock Location.......................................................... 2-23
3-1
3-2
3-3
3-4
3-5
3-6
3-7
3-8
3-9
3-10
UHF Amplifier Tray Assembly...........................................................3-1
Remaining Power after Failure of Amplifier Modules ...........................3-2
Location of the Assemblies in the UHF Amplifier.................................3-3
Block Diagram of the UHF Amplifier Tray ..........................................3-4
Interconnect Typical UHF Amplifier Tray Assembly .............................3-5
AC Wiring Harness UHF Amplifier Cabinet ....................................... 3-14
Interconnect Linear Power Supply #1, Top...................................... 3-17
Interconnect Linear Power Supply #2, Bottom ................................ 3-18
Control Interconnect Cabinet Full Controller System ........................ 3-19
Control Interconnect Cabinet Half Controller System ........................ 3-23
Volume 2, Rev. 0
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November 16, 2009
Innovator® HXB Series, Digital,
UHF Transmitter
Table of Contents
LIST OF TABLES
TABLE
2-1
2-2
2-3
2-4
PAGE
Serial Cable Pin Out...................................................................... 2-14
Cabinet Controller SW2 DIP Switch Settings.................................... 2-16
Cabinet Controller Assembly Problem Resolution Guide .................... 2-17
Amplifier Cabinet Connections ....................................................... 2-21
3-1
3-2
3-3
3-4
3-5
3-6
3-7
3-8
Assemblies in the UHF Amplifier.......................................................3-2
Module OK LED Red and Blinking Interpretation ................................3-5
Module OK LED Red and Blinking Interpretation .............................. 3-10
Module OK LED Red and Blinking Interpretation .............................. 3-12
RF Connectors on the Front Panel .................................................. 3-14
Operating Voltage Connection (Rear Panel)..................................... 3-14
Configuration of SW2 on Full Amplifier Cabinet Control Board ........... 3-22
Configuration of SW2 on Half Amplifier Cabinet Control Board........... 3-25
Volume 2, Rev. 0
November 16, 2009
Innovator HXB Series Digital
UHF Transmitter
Chapter 1, Introduction
Chapter 1:
Introduction
The Innovator HXB Series UHF digital
solid-state transmitter is comprised of
two cabinet types: An exciter/control
cabinet and a UHF amplifier cabinet.
Every Innovator HXB includes one or
more of each cabinet type, dependent
upon the power configuration ordered.
This volume, Volume 2, of the manual
describes the UHF amplifier cabinet
portion of the transmitter. The system
and the exciter/control assemblies are
covered in Volume 1.
servicing procedures before working on
the transmitter.
1.1: Manual Overview
Single Point Breaker or Disconnect The customer should provide a single
point breaker or disconnect at the
breaker box for the main AC input
connection to the transmitter.
Hazardous Accessibility – Axcera has
made attempts to provide appropriate
connectors, wiring and shields to
minimize hazardous accessibility.
Circuit Breakers and Wiring – All
circuit breakers and wire are UL and CE
rated and are rated for maximum
operating conditions.
Volume 2, of the Innovator HXB Series
Digital UHF Transmitter Instruction
Manual, is divided into three chapters
and supporting appendices. Chapter 1,
Introduction, contains information on
safety, return procedures, and
warranties. Chapter 2, Amplifier
Cabinet, describes the UHF amplifier
cabinet. Chapter 3, UHF Amplifier Tray
Assembly and Cabinet Assemblies Circuit
Descriptions, contains a detailed
discussion of the UHF amplifier module
and power supply assemblies that are
contained in the cabinet. Appendix A
contains the RF amplifier cabinet
assembly drawings and parts lists.
Appendix B contains the UHF amplifier
Tray assembly drawings and parts lists.
Appendix C contains the top and bottom
+48VDC power supply assemblies’
drawings and parts lists.
Transmitter Ratings - The transmitter
ratings are provided in the text of this
manual along with voltage and current
values for the equipment.
Protective Earthing Terminal – A main
protective earthing terminal is provided
for equipment required to have
protective earthing.
Read All Instructions – All of the
operating and safety instructions should
be read and understood before operating
this equipment.
Retain Manuals – The manuals for the
equipment should be retained at the site
in which the equipment is operating for
future reference. We provide two sets of
manuals for this purpose; one set can be
left at the office while one set can be
kept at the site.
1.2: Safety
The HXB Series UHF transmitters
manufactured by Axcera are designed to
be easy to use and repair while providing
protection from electrical and mechanical
hazards. Listed throughout the manual
are notes, cautions, and warnings
concerning possible safety hazards that
may be encountered while operating or
servicing the transmitter. It is important
that users review these warnings and
become familiar with the operation and
Volume 2, Rev. 0
Heed all Notes, Warnings, and
Cautions – All of the notes, warnings,
and cautions listed in this safety section
and throughout the manual must be
followed.
1-1
Innovator HXB Series Digital
UHF Transmitter
Chapter 1, Introduction
Follow Instructions – All of the
operating and use instructions for the
product should be followed.
relevant appendix that contains the
drawings for that item.
The cables that connect between the
boards within a tray or assembly and
that connect between the trays, racks
and cabinets are labeled using markers.
Figure 1 is an example of a marked
cable. There may be as few as two or
as many as four Markers on any one
cable. These markers are read starting
farthest from the connector. If there
are four Markers, the marker farthest
from the connector is the system
number such as system 1 or translator
2. The next or the farthest Marker is the
rack or cabinet “A” number on an
interconnect cable or the board “A”
number when the cable is within a tray.
The next number on an interconnect
cable is the Tray location or Board “A”
number. The marker closest to the
connector is the jack or connector “J”
number on an interconnect cable or the
jack or connector “J” number on the
board when the cable is within a tray.
Cleaning – Unplug or otherwise
disconnect all power from the equipment
before cleaning. Do not use liquid or
aerosol cleaners. Use a damp cloth for
cleaning.
Ventilation – Openings in the cabinet
and module front panels are provided for
ventilation. To ensure the reliable
operation of the transmitter, and to
protect the unit from overheating, these
openings must not be blocked.
Servicing – Do not attempt to service
this product yourself until becoming
familiar with the equipment. If in doubt,
refer all servicing questions to qualified
Axcera service personnel.
Replacement Parts – When
replacement parts are needed, be sure
that the parts have the same functional
and performance characteristics as the
original part. Unauthorized substitutions
may result in fire, electric shock, or other
hazards. Please contact the Axcera
Technical Service Department if you have
any questions regarding service or
replacement parts.
Figure 1-1: Marker Identification
Drawing
1.3: Assembly Designators
1.4: Material Return Procedure
Axcera has assigned assembly numbers,
Ax designations such as A1, where
x=1,2,3…etc, to all assemblies, modules,
and boards in the system. These
designations are referenced in the text of
this manual and shown on the block
diagrams and interconnect drawings
provided in the appendices. The Block
Diagrams, Interconnects, Schematics,
Assembly Drawings and Parts Lists are
arranged in increasing numerical order in
the appendices. Section titles in the text
for assembly or module descriptions or
alignment procedures contain the
associated part number(s) and the
Volume 2, Rev. 0
To insure the efficient handling of
equipment or components that have been
returned for repair, Axcera requests that
each returned item be accompanied by a
Return Material Authorization Number
(RMA#).
The RMA# can be obtained from any
Axcera Service Engineer by contacting
the Axcera Technical Service Department
at 1-724-873-8100 or by fax at 1-724873-8105. This procedure applies to all
items sent to the Technical Service
Department regardless of whether the
1-2
Innovator HXB Series Digital
UHF Transmitter
Chapter 1, Introduction
item was originally manufactured by
Axcera.
operated in accordance with Axcera's
operating instructions. This warranty
shall not apply to tubes, fuses,
batteries, or bulbs.
When equipment is sent to the field on
loan, the RMA# is included with the unit.
The RMA# is intended to be used when
the unit is returned to Axcera. In
addition, all shipping material should be
retained for the return of the unit to
Axcera.
Warranties are valid only when and if
(a) Axcera receives prompt written
notice of breach within the period of
warranty, (b) the defective product is
properly packed and returned by the
buyer (transportation and insurance
prepaid), and (c) Axcera determines, in
its sole judgment, that the product is
defective and not subject to any misuse,
neglect, improper installation,
negligence, accident, or (unless
authorized in writing by Axcera) repair
or alteration.
Replacement assemblies are also sent
with the RMA# to allow for the proper
routing of the exchanged hardware.
Failure to close out this type of RMA# will
normally result in the customer being
invoiced for the value of the loaner item
or the exchange assembly.
When shipping an item to Axcera, please
include the RMA# on the packing list and
on the Axcera-provided shipping
container. The packing slip should also
include contact information and a brief
description of why the unit is being
returned.
Axcera's exclusive liability for any
personal and/or property damage
(including direct, consequential, or
incidental) caused by the breach of any
or all warranties, shall be limited to the
following: (a) repairing or replacing (in
Axcera's sole discretion) any defective
parts free of charge (F.O.B. Axcera’s
plant) and/or (b) crediting (in Axcera's
sole discretion) all or a portion of the
purchase price to the buyer.
Please forward all RMA items to:
Axcera
Customer Service Department
103 Freedom Drive
P.O. Box 525
Lawrence, PA 15055-0525 USA
Equipment furnished by Axcera, but not
bearing its trade name, shall bear no
warranties other than the special hoursof-use or other warranties extended by
or enforceable against the manufacturer
at the time of delivery to the buyer.
NO WARRANTIES, WHETHER
STATUTORY, EXPRESSED, OR
IMPLIED, AND NO WARRANTIES OF
MERCHANTABILITY, FITNESS FOR
ANY PARTICULAR PURPOSE, OR
FREEDOM FROM INFRINGEMENT,
OR THE LIKE, OTHER THAN AS
SPECIFIED IN PATENT LIABILITY
ARTICLES, AND IN THIS ARTICLE,
SHALL APPLY TO THE EQUIPMENT
FURNISHED HEREUNDER.
For more information concerning this
procedure, call the Axcera Technical
Service Department.
Service can also be contacted through email at service@axcera.com and on the
Web at www.axcera.com.
1.5: Limited One-Year Warranty for
Axcera Products
Axcera warrants each new product that
it has manufactured and sold against
defects in material and workmanship
under normal use and service for a
period of one (1) year from the date of
shipment from Axcera's plant, when
Volume 2, Rev. 0
1-3
Innovator HXB Series Digital
UHF Transmitter
Chapter 1, Introduction

 WARNING!!!
 HIGH VOLTAGE 
DO NOT ATTEMPT TO REPAIR OR TROUBLESHOOT THIS EQUIPMENT UNLESS
YOU ARE FAMILIAR WITH ITS OPERATION AND EXPERIENCED IN
SERVICING HIGH VOLTAGE EQUIPMENT. LETHAL VOLTAGES ARE PRESENT
WHEN POWER IS APPLIED TO THIS SYSTEM. IF POSSIBLE, TURN OFF
POWER BEFORE MAKING ADJUSTMENTS TO THE SYSTEM.
 RADIO FREQUENCY RADIATION HAZARD 
MICROWAVE, RF AMPLIFIERS AND TUBES GENERATE HAZARDOUS RF
RADIATION THAT CAN CAUSE SEVERE INJURY INCLUDING CATARACTS,
WHICH CAN RESULT IN BLINDNESS. SOME CARDIAC PACEMAKERS MAY BE
AFFECTED BY THE RF ENERGY EMITTED BY RF AND MICROWAVE
AMPLIFIERS. NEVER OPERATE THE TRANSMITTER SYSTEM WITHOUT A
PROPERLY MATCHED RF ENERGY ABSORBING LOAD ATTACHED.
KEEP
PERSONNEL AWAY FROM OPEN WAVEGUIDES AND ANTENNAS. NEVER
LOOK INTO AN OPEN WAVEGUIDE OR ANTENNA. MONITOR ALL PARTS OF
THE RF SYSTEM FOR RADIATION LEAKAGE AT REGULAR INTERVALS.
Volume 2, Rev. 0
1-4
Innovator HXB Series Digital
UHF Transmitter
Chapter 1, Introduction
EMERGENCY FIRST AID INSTRUCTIONS
Personnel engaged in the installation, operation, or maintenance of this equipment are urged to become
familiar with the following rules both in theory and practice. It is the duty of all operating personnel to be
prepared to give adequate Emergency First Aid and thereby prevent avoidable loss of life.
RESCUE BREATHING
1. Find out if the person is
breathing.
You must find out if the person
has stopped breathing. If you
think he is not breathing, place
him flat on his back. Put your ear
close to his mouth and look at his
chest. If he is breathing you can
feel the air on your cheek. You
can see his chest move up and
down. If you do not feel the air
or see the chest move, he is not
breathing.
2. If he is not breathing, open
the airway by tilting his head
backwards.
Lift up his neck with one hand
and push down on his forehead
with the other. This opens the
airway. Sometimes doing this will
let the person breathe again by
himself.
3. If he is still not breathing,
begin rescue breathing.
-Keep his head tilted backward.
Pinch nose shut.
-Put your mouth tightly over his
mouth.
-Blow into his mouth once every
five seconds.
-DO NOT STOP rescue breathing
until help arrives.
LOOSEN
WARM
CLOTHING
KEEP
Do this when the victim is
breathing by himself or help is
available. Keep him as quiet as
possible and from becoming
chilled. Otherwise treat him for
shock.
BURNS
SKIN REDDENED: Apply ice cold water to burned
area to prevent burn from going deeper into skin
tissue. Cover area with a clean sheet or cloth to
keep away air. Consult a physician.
SKIN BLISTERED OR FLESH CHARRED: Apply
ice cold water to burned area to prevent burn from
going deeper into skin tissue.
Volume 2, Rev. 0
Cover area with clean sheet or cloth to keep away
air. Treat victim for shock and take to hospital.
EXTENSIVE BURN - SKIN BROKEN: Cover area
with clean sheet or cloth to keep away air. Treat
victim for shock and take to hospital.
1-5
Innovator HXB Series Digital
UHF Transmitter
Chapter 2, Amplifier Cabinet
Chapter 2:
Amplifier Cabinet
2.1: Cabinet Overview
All equipment in the cabinet is fully
solid-state and designed for highoperational reliability and a servicefriendly layout. The cabinet is cooled by
external air cooling equipment. The
cooling air is ducted into and out of the
top of the cabinet.
The fully populated amplifier cabinets
used in Innovator HXB Transmitters
contain eight UHF amplifiers connected
in parallel (Figure 2-1). The number of
amplifiers varies according to the
needed output power for the
transmitter. The amplifiers operate,
without the need for tuning or
alignment, on the UHF channel
designated.
(A17) UHF AMPLIFIER #1
(Not present in 2.5kW)
(A19) UHF AMPLIFIER #3
(Not present in 2.5kW)
(A18) UHF AMPLIFIER #2
(Not present in 2.5kW)
(A20) UHF AMPLIFIER #4
(Not present in 2.5kW)
(A21) UHF AMPLIFIER #5
(A23) UHF AMPLIFIER #7
(A22) UHF AMPLIFIER #6
(A24) UHF AMPLIFIER #8
POWER SUPPLY #1
CIRCUIT BREAKER
±12VDC POWER SUPPLY
RESET BREAKERS
POWER SUPPLY #2
CIRCUIT BREAKER
Figure 2-1: Typical 8 Way UHF Amplifier Cabinet (Front View)
Volume 2, Rev. 0
2-1
Innovator HXB Series Digital
UHF Transmitter
Chapter 2, Amplifier Cabinet
Figure 2-2: Block Diagram of the typical UHF Amplifier Cabinet 8 Way (5kW)
2.2: Description of the UHF Amplifier
Cabinet
the input and output air connections on
the top of the amplifier cabinet.
The features of the amplifier cabinet
include: 1) Amplifiers that are 100%
transistors. 2) High redundancy due to
the parallel connection of power
transistors. 3) A mean junction
temperatures less than 120° C. 4)
Multiple fault protection circuitry in each
amplifier. 5) A power supply for
Amplifiers 1 thru 3 (3.7kW) and 4
(5kW). 6) A separate power supply for
Amplifiers 6 thru 8 (1.8kW) and 5
(2.5kW & 5kW). 7) Amplifiers that
operate over the selected band of UHF
frequencies without the need for
alignment. 8) The important operating
parameters are displayed in the
transmitter touch screen control unit. 9)
There are multiple test points in the
signal path. 10) It has air cooling, with
The amplifier assemblies in each
amplifier cabinet (see Figure 2-3) are
slide-in units, inserted from the front.
In a 5kW cabinet, two 4 way splitters
are installed, one in the top and one in
the bottom half of the cabinet. In a 2.5
kW cabinet, just the bottom 4 way
splitter is present. These splitters
distribute the RF input to each of the
amplifiers. In a 3.7kW cabinet, 3 way
splitters are installed in the top and
bottom half of the cabinet. In a 1.8 kW
cabinet, just the bottom 3 way splitter is
present. These distribute the RF input
to each of the amplifiers. A 3, 4, 6 or 8
way combiner is installed in the middle
of the cabinet. The lower part of the
cabinet accommodates a power
distribution panel that contains two 480
Volume 2, Rev. 0
2-2
Innovator HXB Series Digital
UHF Transmitter
Chapter 2, Amplifier Cabinet
VAC 30 Amp 3 Phase or 208 VAC 50
Amp 3 Phase circuit breakers for 3.7 & 5
kW or one circuit breaker for 1.8 & 2.5
kW. The left breaker, if present,
distributes the main AC voltage to the
top power supply and the right circuit
breaker controls the bottom power
supply. The top power supply provides
the +48 VDC to the top three or four
amplifier assemblies. The bottom power
supply provides the +48 VDC to the
bottom three or four amplifier
assemblies
connect to the (A21) UHF amplifier #5,
(A22) UHF amplifier #6, (A23) UHF
amplifier #7, and (A24) UHF amplifier
#8. The eight outputs of the amplifier
modules at 7/16” connectors (+58.3
dBm, 675W) are cabled to the (A24) 8
way combiner. The output of the
combiner connects to the (A26) RF
coupler. The output of the cabinet is
approximately (+67.2 dBm, 5.2kW) at
the 3-1/8” output connector of the (A26)
RF Coupler Assembly.
2.2.2: 3.7 kW Amplifier Cabinet with
6 Amplifier Assemblies
There is also either one or two 1 Amp
reset circuit breakers, mounted on the
power distribution panel that protect the
AC voltage to the switching power
supply, located in the bottom and top
power supply. If one breaker is present,
it connects to the bottom power supply,
for 1.8 & 2.5 kW. If 2 one Amp reset
breakers are present, the second one
amp breaker connects to the top power
supply for 3.7 & 5 kW. The switching
supply provides the ±12 VDC to the top
and bottom amplifier assemblies.
The DTV RF signal from the
exciter/control cabinet is connected
through RG-55 cable through an opening
in the roof in the UHF amplifier cabinet.
The RF (+27 dBm, 500 mW) from the
output of the exciter control cabinet
connects to the SMA “S” input on (A14)
a 2 way splitter with each of the two
outputs connecting to a 3 way splitter
panel (A15 top & A16 bottom). The
three outputs of the (A15) Top 3 way
splitter are at the “N” connectors X1-X3.
2.2.1: 5 kW Amplifier Cabinet with 8
Amplifier Assemblies
The outputs (+18 dBm, 63 mW) connect
to the (A17) UHF amplifier #1, (A18)
UHF amplifier #2 and (A19) UHF
amplifier #3. The three outputs of the
(A16) Bottom 3 way splitter, at “N”
connectors X2-X4, connect to the (A22)
UHF amplifier #6, (A23) UHF amplifier
#7, and (A24) UHF amplifier #8. Each
amplifier tray has a gain of
approximately +40.5dB. The six
outputs of the amplifier modules at
7/16” connectors (+58.5 dBm, 700W)
are cabled to the (A24) 6 way combiner.
The output of the combiner connects to
the (A26) RF coupler. The output of the
cabinet is approximately (+65.7 dBm,
3.7 kW) at the 3-1/8” output connector
of the (A26) RF Coupler Assembly.
Refer to Figure 2-2. The DTV RF signal
from the exciter/control cabinet is
connected through RG-55 cable through
an opening in the roof in the UHF
amplifier cabinet. The RF (+26 dBm,
400 mW) from the output of the exciter
control cabinet connects to the SMA “S”
input on (A14) a 2 way splitter with each
of the two outputs connecting to a 4
way splitter panel (A15 top & A16
bottom). The four outputs of the (A15A1) Top 4 way splitter are at the “N”
connectors X1-X4.
The outputs (+15.3 dBm, 34 mW)
connect to the (A17) UHF amplifier #1,
(A18) UHF amplifier #2, (A19) UHF
amplifier #3 and (A20) UHF amplifier
#4. Each amplifier tray has a gain of
approximately +40.5dB. The four
outputs of the (A16-A1) Bottom 4 way
splitter, at “N” connectors X1-X4,
Volume 2, Rev. 0
2.2.3: 2.5 kW Amplifier Cabinet with
4 Amplifier Assemblies
Refer to Figure 2-3. The DTV RF signal
from the exciter/control cabinet is
2-3
Innovator HXB Series Digital
UHF Transmitter
Chapter 2, Amplifier Cabinet
connected through RG-55 cable through
an opening in the roof in the UHF
amplifier cabinet. The RF (+26 dBm,
400 mW) from the output of the exciter
control cabinet connects to the 4 way
splitter panel (A16) mounted at the
bottom of the cabinet. The four outputs
of the (A16-A1) 4 way splitter, at “N”
connectors X1-X4, connect to the (A21)
UHF amplifier #5, (A22) UHF amplifier
#6, (A23) UHF amplifier #7, and (A24)
UHF amplifier #8. Each amplifier tray
has a gain of approximately +40.5dB.
The four outputs of the amplifier
modules at 7/16” connectors (+58.5
dBm, 700W) are cabled to the (A25) 4
way combiner assembly. The combiner
produces a single output that connects
to the (A26) RF Coupler Assembly. The
RF output for the cabinet, approximately
+64.1 dBm, 2570 Watts, is at the 3-1/8”
output connector of the RF Coupler
Assembly.
2.2.4: 1.8 kW Amplifier Cabinet with
3 Amplifier Assemblies
The DTV RF signal from the
exciter/control cabinet is connected
through RG-55 cable through an opening
in the roof in the UHF amplifier cabinet.
The RF (+27 dBm, 500 mW) from the
output of the exciter control cabinet
connects to the 3 way splitter panel
(A16) mounted at the bottom of the
cabinet. The three outputs of the (A16)
3 way splitter, at “N” connectors X2-X4,
connect to the (A22) UHF amplifier #6,
(A23) UHF amplifier #7, and (A24) UHF
amplifier #8. Each amplifier tray has a
gain of approximately +40.5dB. The
three outputs of the amplifier modules
at 7/16” connectors (+58.5 dBm, 700W)
are cabled to the (A25) 3 way combiner
assembly. The combiner produces a
single output that connects to the (A26)
RF Coupler Assembly. The RF output for
the cabinet, approximately +62.6 dBm,
1800 Watts, is at the 3-1/8” output
connector of the RF Coupler Assembly.
Figure 2-3: Block Diagram of the typical UHF Amplifier Cabinet 4 Way (2.5kW)
Volume 2, Rev. 0
2-4
Innovator HXB Series Digital
UHF Transmitter
Chapter 2, Amplifier Cabinet
Components in the Amplifier Cabinet
Splitter 1 : 4 (5kW)
Splitter 1 : 3 (3.7kW)
8 UHF Amplifier Trays (5kW)
6 UHF Amplifier Tray (3.7kW)
2 Power Supply Assemblies (3.7 &
5kW)
UHF Amplifier Trays (A17,
A18, A19 & A20) (5kW)
(A20) not used in 3.7kW
4 UHF Amplifier Trays (2.5kW)
3 UHF Amplifier Trays (1.8kW)
1 Power Supply Assembly (1.8 &
2.5kW)
One Circuit Breaker Assembly
One 3, 4, 6 or 8 Way Combiner
Assembly
Combiner
Combiner
Combiner
Combiner
(5kW)
(3.7kW)
(2.5kW)
(1.8kW)
UHF Amplifier Trays
(A21, A22, A23 & A24)
(2.5kW & 5kW)
(A21) not used in 1.8 & 2.7kW
Splitter 1 : 4 (2.5kW & 5kW)
Splitter 1 : 3 (1.8kW & 3.7kW)
Circuit Breaker for Top
+48VDC Power Supply (3.7kW & 5kW)
Circuit Breaker for Top
12VDC Power Supply (3.7kW &
5kW) Assembly
Circuit Breaker for Bottom
12VDC Power Supply (1.8, 2.5 &
5kW) Assembly
Circuit Breaker for Bottom +48VDC
Power Supply (1.8, 2.5 3.7 & 5kW)
Figure 2-4: Components in the Amplifier Cabinet
Volume 2, Rev. 0
2-5
Volume 2, Rev. 0
Innovator HXB Series Digital
UHF Transmitter
2-6
Figure 2-5: Block Diagram Typical UHF Amplifier Tray Assembly
Chapter 2, Amplifier Cabinet
Innovator HXB Series Digital
UHF Transmitter
Chapter 2, Amplifier Cabinet
2.3: Description of the HXB UHF
Amplifier Tray
(1311943; Appendix B)
Coupler Board (131882) that supplies a
RF sample out at J1, that connects to
the front panel. Also, the Coupler Board
provides a final amp forward metering
sample at J3-1 and a final amp reflected
metering sample at J3-2. The samples
are connected to (A17) the FET switch/
metering board (1312342) at J1-6 and
J1-7. The samples are not used on the
FET switch/metering board, they are just
fed through to J15-2 and J15-14 that
are wired to J3-12 and J3-25 on the
amplifier control board where they are
used in the amplifier protection circuitry.
The RF output of the coupler board is at
J2 that is Bus wire connected to J2 the
7/16” connector RF Output Jack of the
amplifier assembly. Typical output level
is +58.9 dBm ATSC.
There are eight of these trays in an 8
way Amplifier Cabinet Assembly for
5kW, six in a 6 way Amplifier Cabinet
Assembly for 3.7 kW, four in a 4 way
Amplifier Cabinet Assembly for 2.5 kW,
or three in a 3 way Amplifier Cabinet
Assembly for 1.8 kW. The Amplifier
Tray has an approximate gain of +40.5
dB.
The RF input (+15 dBm ATSC) at the
“N” connector J1 on each UHF amplifier
assembly is fed to the RF input
connections on (A1) the Phase/Gain
Board (1311583), whichprovides phase
adjustment and gain control of the RF
signall. The Phase/Gain Board is also a
predriver with ≈9 dB gain. The output
(+24 dBm) is cabled to the RF input
connections on (A2) a Dual BLF871
Amplifier Pallet Assembly (1311991)
with ≈18 dB gain. The output (+42
dBm) is fed to J9 on (A12) a Coupler
Board (1311882) that supplies a driver
forward power sample out of J3-5 to the
FET switch/metering board at J1-1. The
sample is not used on the FET
switch/metering board (1312342); it is
just fed through to J15-1 that is wired to
J3-13 on the (A14) amplifier control
board (1311683) where it is used in the
amplifier protection circuitry. The output
of the coupler board at J8 (+42 dBm) is
fed to J1 on (A4) the 4 Way Splitter
Board (1306371) where it is split. Each
output of the splitter (+36 dBm) is
cabled to the RF Input jack of one of the
four (A5-A8), UHF pallet broadband
amplifier boards, BLF878 (1313170).
Each pallet board has ≈+18 dB of gain.
The outputs of each amplifier board
(+54 dBm) are combined on (A13) the 4
way broadband combiner assembly,
(1311945).
2.3.1: Description of the 8 Way
Combiner Assembly (5 kW Amplifier
Cabinet)
The RF outputs of the eight amplifiers
are combined by means of an 8:1
combiner assembly that is mounted in
the middle of the cabinet. The 8 way
combiner is made up of two identical 4
way combiners and a two way combiner.
Refer to Figure 2-6.
The outputs of the top four amplifier
trays, ≈+58.9 dBm in level, connect to
the (A1) 4 Way combiner. The outputs
of the bottom four amplifier trays,
≈+58.9 dBm in level, connect to the
(A2) 4 Way combiner. Each 4 Way
combiner has three dummy loads, two
600W and a 1200W, connected to them,
which dissipate any power due to an
imbalance or mismatch during the
combining of the amplifiers. The
outputs of the two 4 way combiners,
each ≈+64.1 dBm, connect to the (A3)
Two Way Combiner. The 2 Way
combiner has a 2500W load connected
to it. The output of the 2 Way
Combiner, which is the output of the 8
Way Combiner Assembly, is at the 3
1/8” RF output jack, typically ≈+67
dBm.
The RF output jack J2, of the 4 way
combiner assembly (+58.9 dBm), is Bus
wire jumpered to J4 on the (A12)
Volume 2, Rev. 0
2-7
Volume 2, Rev. 0
Innovator HXB Series Digital
UHF Transmitter
2-8
Figure 2-6: Block Diagram Typical 8 Way UHF Combiner Assembly
Chapter 2, Amplifier Cabinet
Innovator HXB Series Digital
UHF Transmitter
Chapter 2, Amplifier Cabinet
2.3.1.1: Description of the 6 Way
Combiner Assembly (3.7 kW
Amplifier Cabinet)
2.3.1.3: Description of the 3 Way
Combiner Assembly (1.8 kW
Amplifier Cabinet)
The RF outputs of the six amplifiers are
combined by means of an 6:1 combiner
assembly that is mounted in the middle
of the cabinet. The 6 way combiner is
made up of two identical 3 way
combiners and a two way combiner.
The RF outputs of the three amplifiers
are combined by means of a 3:1
combiner assembly that is mounted in
the middle of the cabinet.
The three RF inputs, ≈+58.9 dBm
Digital in level, each connect to an input
to the 3 Way combiner. The combiner
has two 600W dummy loads, which
dissipate any power due to an imbalance
or mismatch during the combining of the
amplifiers. The output of the 3 Way
Combiner Assembly is at the 1 5/8” RF
output jack, typically ≈+62.6 dBm
Digital.
The outputs of the top thee amplifier
trays, ≈+58.9 dBm in level, connect to
the (A1) 3 Way combiner. The outputs
of the bottom three amplifier trays,
≈+58.9 dBm in level, connect to the
(A2) 3 Way combiner. Each 3 Way
combiner has two 600W dummy loads,
which dissipate any power due to an
imbalance or mismatch during the
combining of the amplifiers. The
outputs of the 3 way combiners, each
+64.1 dBm, connect to the (A5) Two
Way Combiner. The 2 Way combiner
has a 2500W load connected to it. The
output of the 2 Way Combiner, which is
the output of the 6 Way Combiner
Assembly is at the 3 1/8” RF output
jack, typically ≈+65.7 dBm.
2.3.2: Removal of an Amplifier
Assembly
The amplifiers are of broadband design
and cover the frequencies for the entire
UHF band without the need for
alignment or adjustment.
For reasons of safety, amplifier modules
MUST be in standby (RF disabled)
before any connections are removed. If
the amplifier control board is loaded
with software version 2.4 or higher, an
Axcera Amplifier disable plug (1308219)
can be used to place an individual
module in standby. If your amplifier
module has a front panel disable switch,
this switch can be used to disable the
amplifier. Regardless of the version of
code, any power amplifier may safely be
removed by disabling its power supply.
The power supply, either the top power
supply #1 for the top four Amplifier
assemblies, or the bottom power supply
#2 for the bottom three Amplifier
assemblies, may be isolated from main
AC power by switching off the
appropriate front panel circuit breaker.
This is accomplished by tripping the
respective breaker located on the circuit
breaker assembly panel, at the bottom
of the amplifier cabinet.
2.3.1.2: Description of the 4 Way
Combiner Assembly (2.5 kW
Amplifier Cabinet)
The RF outputs of the four amplifiers are
combined by means of a 4:1 combiner
assembly that is mounted in the middle
of the cabinet.
The four RF inputs, ≈+58.9 dBm Digital
in level connect to the 4 way combiner.
The 4 Way combiner has three dummy
loads, two 600W and a 1200W, which
dissipate any power due to an imbalance
or mismatch during the combining of the
amplifiers. The output of the 4 Way
Combiner Assembly is at the 1 5/8” RF
output jack, typically ≈+64.1 dBm
Digital.
Volume 2, Rev. 0
2-9
Innovator HXB Series Digital
UHF Transmitter
Chapter 2, Amplifier Cabinet
To remove a disabled amplifier
assembly, first remove the input cable
connected to the top connector then the
output cable connected to the bottom
connector on the front panel of the
assembly. They must be removed in
this sequence to prevent damage to the
amplifier assemblies. Then loosen the
two fixing screws, one located at the
top, middle and one at the bottom,
middle of the assembly. The amplifier
can then be pulled from the cabinet. To
replace the assembly, insert the
assembly into the slots and replace the
two fixing screws. Then connect the RF
output cable first and the RF input cable
last, they must be replaced in this
sequence to prevent damage to the
amplifier assemblies.
The AC input voltages to the power
supplies are controlled through two 480
VAC 30 Amp 3 Phase or two 208 VAC 50
Amp 3 Phase circuit breakers located on
the AC distribution panel mounted at the
bottom of the cabinet (3.7 kW & 5 kW).
There is only one 480 VAC or 208 VAC
circuit breaker in a 1.8 kW & 2.5 kW
amplifier cabinet.
2.3.4: Control and Monitoring
Each amplifier has multiple-fault
protection circuitry that prevents
damage to or destruction of the power
transistors during critical operating
conditions, such as high reflected power,
overtemperature, overcurrent, or
overvoltage. Furthermore, the operating
voltages and currents of the amplifiers
are monitored in the power supply units
as well as the mains voltage. All
important amplifier operating
parameters, such as drain currents, RF
power, and heat sink temperatures, are
connected to the control unit.
The paralleling network of the amplifier
cabinet with its load balancing resistors
is designed so that operation continues
at reduced power when one or more
amplifiers are removed or failed.
All RF cables from the outputs of the
first splitter up to the output of the
output combiner assembly are phase
matched (in phase) to the particular
frequency and their lengths must again
be determined when a change in
operating frequency is made. All
amplifier cabinets of a transmitter, from
cabinet input to cabinet output, are also
aligned to the same phase with equal
length cables.
2.3.5: Cabinet Cooling
The amplifier cabinet is exclusively air
cooled as shown in Figure 2-7. The
cooling system is exemplified by low
airflow requirements, low noise levels,
and high efficiency. With an inlet air
temperature of +25° C, the junction
temperatures of the RF power
transistors remain under 120°C,
resulting in a high amplifier service life.
2.3.3: Amplifier Cabinet Power
Supply Assemblies
A major fraction of the heat is dissipated
by the amplifiers and their power
supplies. This heat is carried away by an
external cooling system. Connections
are available on the top of the amplifier
cabinet for the intake and exhaust of the
air. The amplifiers are equipped with
highly efficient finned heat sinks, which
radiate, into the vertically flowing air
stream, the heat generated by the
power transistors. By utilizing special
construction techniques in the cabinet,
as well as employing conservatively
dimensioned ducting, a uniform
distribution of cooling air over the
The voltages to the UHF Amplifier Trays
are supplied by two +48 VDC power
supply assemblies. One supply, the top
power supply #1, provides the +48 VDC
to the three or four UHF amplifier
assemblies mounted at the top of the
cabinet (3.7 kW or 5 kW). The other
supply, the bottom power supply #2,
provides the +48 VDC to the three or
four UHF amplifier assemblies mounted
at the bottom of the cabinet (1.8 kW,
2.5 kW, 3.7 kW, & 5 kW).
Volume 2, Rev. 0
2-10
Innovator HXB Series Digital
UHF Transmitter
Chapter 2, Amplifier Cabinet
various heat sinks is achieved. This
ensures that all of the power transistors
are at essentially the same temperature.
Temperature test points connected to
special monitoring circuits are located in
the amplifiers and power supply units.
Under over temperature conditions, the
monitoring circuits respond and switch
off the respective unit. In addition, a
fault indication and the measured value
are passed to the control unit.
Control connections to the Blower is
through the terminal block TB1 located
at the rear upper right of the amplifier
cabinets. TB1-1 is +12 VDC and TB1-3
is Blower Control that connect to the Fan
Control in the Blower Cabinet.
Amplifiers
Amplifiers
Example for the connection of air ducting to the roof of the cabinet
Figure 2-7: Air Flow in the Amplifier Cabinet
Volume 2, Rev. 0
2-11
Innovator HXB Series Digital
UHF Transmitter
Chapter 2, Amplifier Cabinet
Figure 2-9: Half Cabinet Controller
Assembly
Figure 2-8: Full Cabinet Controller
Assembly
2.4: Cabinet Controller Assembly
The Innovator HXB cabinet controllers
are designed to control and monitor
components contained in the amplifier
cabinet. A full cabinet controller, Figure
2-8, monitors and controls all
components of the amplifier cabinet
while a half cabinet controller, Figure 29, monitors and controls only half of the
cabinet. Two half cabinet controller
assemblies are used in single amplifier
cabinet configurations to give the
transmitter redundancy by allowing the
top or the bottom amplifiers to operate
if the other half cabinet controller
assembly should malfunction. When two
half cabinet controller assemblies are
needed, they are mounted on the power
supply covers in the rear of the amplifier
cabinet. The wire harness connection of
J120 pin 8 is used by the half cabinet
controller to determine if it is installed
as an upper half cabinet controller or a
lower half cabinet controller.
Volume 2, Rev. 0
2-12
Status and control of each amplifier
cabinet is implemented through serial
commands that are transferred between
the transmitter's system controller and
the amplifier cabinet controller(s). Both
types of cabinet controller assemblies
contain two UARTs, Universal
Asynchronous Receiver-Transmitter ICs.
One of the controller’s UARTs is used
exclusively to communicate with
amplifiers within the cabinet. The
second UART provides status and control
of the cabinet to the transmitter's
control system. Serial debug port J108
is a standard read only RS-232 serial
port that is designed only for use with
Axcera factory test software. Status and
control of devices within the amplifier
cabinet is implemented through discrete
wired connections and serial messages
sent between the amplifier control
boards, located in the individual
amplifier modules, and the cabinet
controller(s).
Innovator HXB Series Digital
UHF Transmitter
Chapter 2, Amplifier Cabinet
The full cabinet controller obtains
+15VDC and -15VDC from one or two
switching power supplies located in the
lower front portion of the amplifier
cabinet. The half cabinet controller
obtains +15VDC and -15VDC from either
the top or bottom power supply
assembly in the amplifier cabinet
Cabinet controllers contain linear voltage
regulators that convert the +15 VDC to
+12 VDC. The +12 VDC power is
supplied to each of the amplifier
modules through self-resetting fuses.
The top and bottom high voltage power
supplies of the power amplifier cabinet
are regulated by SCR controllers located
in the lower front area of the cabinet.
The cabinet controller monitor the AC
supply voltage to the SCR controllers
and the health of the controllers. Half
cabinet controllers monitor the AC
supply to the upper or lower SCR
controller and the health of the specific
SCR controller.
2.4.1: Controller Connections to the
Transmitter's System Controller
Early systems used potentiometers
located in the cabinet controller
assembly to set the voltage output of
the high power supplies. Later systems
have the voltage level adjust
potentiometers located within the power
supply assembly. If voltage adjust
potentiometers are located within the
power supply, adjustment holes will be
visible through the rear cover of the
power supply assembly labeled, R120123.
Each cabinet controller has a unique
serial address that is determined by the
setting of a rotary switch that is
centrally located at the top of the
cabinet controller assembly. The RS485 serial address of the cabinet
controller is the switch position times
ten plus nine. Example: Amplifier
Cabinet Number 1 uses serial address
19.
RF power monitoring of the amplifier
cabinet is monitored through detectors
located on the cabinet controller board.
Separate aural and visual detectors are
available for externally diplexed
systems, however in earlier models of
the cabinet controller, the forward/visual
reflected power detection was obtained
using the aural reflected power port. In
systems with half cabinet controllers, RF
samples are first split before they are
routed to each half cabinet controller.
Volume 2, Rev. 0
Power amplifier modules mounted in the
amplifier cabinet are number referenced
in this document and the transmitter
control system from left to right and top
to bottom as observed from the front of
the amplifier cabinet. The number one
high voltage power supply is located in
the top of the amplifier chassis. It is
controlled by SCR #1, and circuit
protected by the left breaker located on
the power distribution assembly, in the
lower front of the cabinet. The High
voltage power supply number two is
located in the bottom of the amplifier
cabinet. It is controlled by SCR #2, and
circuit protected by the right breaker
located on the power distribution
assembly. Power supply one, top
supply, feeds amplifiers one through
four while power supply two, bottom
supply, powers amplifiers five through
eight.
2-13
Serial messages between the cabinet
controller(s) and the transmitter's
system controller are transported over a
CAT-5 twisted pair cable using serial
ports J103 and J104. Either port can be
used as an input or output to the next
amplifier cabinet. The wiring of the
CAT-5 cables is a simple pin x to pin x
connection. If a replacement cable or
patch cable are needed, a simple
straight-thru Ethernet cable with two
RJ45 plugs can be used.
Innovator HXB Series Digital
UHF Transmitter
Chapter 2, Amplifier Cabinet
Table 2-1: Serial Cable Pin out
Pin
Function
System Visual AGC #2
Ground
No Connection
System Serial +
System Serial 6
No Connection
System Aural AGC #2
Ground
The CAT-5 cable is also used to
transport two analog reference voltages:
Aural AGC #2 and Visual AGC #2. Each
amplifier module produces a reference
voltage that is proportional to the power
output of the module. The amplifier
circuits and amplifier cabinet wiring are
configured such that the highest
measured reference voltage is selected
and wired to the amplifier cabinet
controller. The cabinet controller board
has circuitry that presents the highest
measured reference voltage to the
transmitter's system controller and
upconverter. In multiple amplifier
cabinet systems, the highest measured
amplifier reference voltage is the voltage
on the CAT-5 cable. In analog systems,
the aural amplifier reference voltages
are separate from the reference voltage
of the visual amplifier modules.
2.4.2: Controller Connections to
Amplifier Cabinet Components
2.4.2.1: Power Amplifiers
Power connections, serial connections
and reference voltage signals are sent
from the cabinet controller to the top
and bottom power supply assemblies
and then to each of the amplifier
modules through one of two DB25
connectors. J101 is used to interface
through the amplifier wiring harness to
the power supply assembly, top which
connects to the amplifiers one through
four. J102 is used to interface to the
power supply assembly, bottom which
connects to the amplifiers five through
eight.
Volume 2, Rev. 0
Status and control of each amplifier
module is implemented through serial
messages sent between the amplifier's
control board and the cabinet controller
assembly. The serial address of each
amplifier module is determined by the
wiring of the amplifier chassis. The
module knows which serial address to
use based on where it is located within
the system. The cabinet controller
board provides +12VDC and -12VDC to
each of the amplifier modules through
individual self-resetting fuses. The
+12VDC supplies of the first four
amplifiers are powered from one voltage
regulator (U14) that is supplied by
+15VDC. A separate voltage regulator
(U17) is used to power the +12VDC
lines of the last four amplifiers. U19 is
used to generate the -12VDC supply to
all of the amplifier positions.
Since some systems have separate aural
and visual power amplifiers, the chassis
wiring of position four and eight can be
wired for either an aural or a visual
amplifier. The reference AGC#2 voltage
of amplifier position four and eight is
wired through pin 22 of J101 / J102 in
digital systems or through pin 25 in
analog systems, where this amplifier
position is used for aural power
amplification. Amplifier modules are
enabled and disabled using a general
broadcast serial message. If an
amplifier does not properly receive the
message or for any other reason it is not
in the desired state, the controller will
individually command the amplifier into
the desired state.
2.4.2.2: High Power Voltage Supply
Controllers
The power amplifier high power voltage
supplies of the amplifier cabinet are
regulated with SCR controllers located in
the lower front area of the cabinet. The
cabinet controller monitors the AC
supply voltage to the SCR controllers
and the health of the controllers. Early
systems used potentiometers located in
the cabinet controller to set the voltage
2-14
Innovator HXB Series Digital
UHF Transmitter
Chapter 2, Amplifier Cabinet
output of the high power supplies. Later
systems have the voltage level adjust
potentiometers located within the power
supply assembly. If the voltage adjust
potentiometers are located within the
power supply, adjustment holes are
visible through the rear cover of the
power supply assembly.
The amplifier cabinet wire harness
connects J120 of the cabinet controller
assembly to the power supply SCR
controllers. If the cabinet controller is
not enabled, the SCR controllers are
held Off with a logic low on position nine
of their terminal block. If the SCR
controller detects an output short, has
an over current fault, or is otherwise not
ready for operation, the specific SCR
controller is held Off. NOTE: Do not
remove power from the cabinet
controllers or disconnect J120 from the
cabinet controller with power applied to
the power amplifier high power supplies.
To allow the power supply to stabilize,
an amplifier module is not enabled until
five seconds after their associated high
power voltage supply has been enabled.
2.4.2.3: Low Power Voltage Supply
and AC Line Monitoring
The cabinet controller obtains its
operating power and power for operation
of the amplifier modules from a +15
VDC power supply located in the lower
front area of the control cabinet. This
supply also contains a +5 VDC output,
which at this time does not have any
significant use. If redundant power
supplies are installed, the system will
operate if only one supply is operational.
Diodes located in the cabinet controller
prevent one supply from disabling the
second power supply. WARNING: THE
HIGH POWER VOLTAGE SUPPLY LINES
ARE LOCATED BEHIND THE FRONT
COVER. REMOVE POWER FROM THIS
AREA BY LOCKING OUT THE HIGH
POWER VOLTAGE FEEDS TO THE
AMPLIFIER CABINET.
The cabinet controller obtains AC line
monitoring samples from a circuit board
Volume 2, Rev. 0
2-15
located in the front of the amplifier
chassis. These signals are line to
ground samples obtained by resistor
dividers. Two unique board assemblies
are used: one for systems that operate
around 220VAC input and another for
systems that are operating around
440VAC. An internal DIP switch located
on the cabinet controller board is used
to scale the input values from the AC
monitoring board. Switch 2 position
four needs to be OFF for 220 VAC
systems and ON for 440 VAC systems.
When a system is configured to operate
around 220 VAC, a phase loss fault is
generated if one or more input phases
measure less than 176 VAC. For
systems operating around 440 VAC, a
phase loss fault is generated if one or
more input phases measure less than
353 VAC.
2.4.2.4: Air Temperature and
Amplifier Temperature Monitoring
The amplifier cabinet inlet air
temperature is monitored by a
thermistor located in the cabinet
controller. A small remote circuit board
is used to monitor the exhaust
temperature of the amplifier chassis.
The exhaust temperature is measured in
the front top center of the amplifier
chassis. At this time, neither the inlet
air temperature nor exhaust air
temperature is used for fault detection.
A cabinet cooling fault is only generated
by the detection of an over temperature
fault in two or more modules of the
amplifier chassis. If an over
temperature fault occurs, all amplifiers
are placed in standby and the fault is
latched. The fault is only cleared when
the amplifier cabinet is placed into
standby mode.
2.4.2.5: RF Power Monitoring
The separate amplifiers modules of the
cabinet are combined prior to connection
to couplers that measure the cabinet's
Innovator HXB Series Digital
UHF Transmitter
Chapter 2, Amplifier Cabinet
RF output power. Separate aural and
visual detectors are available, however
in early models of the cabinet controller,
visual reflected power detection was
implemented using aural reflected power
port J114 instead of J112. Please refer
to cabinet controller settings section, for
proper setting of the DIP switch two
position five.
Sample ports are available to monitor
the RF output energy and the energy
reflected back into the cabinet. Digital
systems monitor forward power on J111
and reflected power on J114. In analog
systems, the aural forward power is
measured on J113, the visual forward
power detection uses J111, and the
visual reflected power is measured using
J112. If an aural system is externally
diplexed, the aural reflected power is
monitored using J114.
2.4.2.6: Reject Load Monitoring
Select UHF amplifier systems require the
use of circulators within the amplifier
cabinet combiner. The reject loads of
these circulators have a limited power
rating therefore the energy into these
loads is monitored.
J120 Pin 10, on the amplifier cabinet
controller, is used to monitor a signal
that is proportional to the highest reject
load energy of amplifier positions one
through four. Pin 13 is used to monitor
the highest reject load energy of
amplifier positions five through eight.
If the reject load voltage of a set of
amplifiers exceeds a preset that is
typically 0.8 VDC, the power supply of
the associated amplifiers and the
amplifiers themselves will be disabled.
NOTE: Reject load faults can only be
cleared by placing the amplifier cabinet
in standby.
2.4.3: Cabinet Controller Settings
Within the cabinet controller assembly is
an eight position DIP switch, SW2 that is
used to enable select features. See
Table 2-2.
Table 2-2: Cabinet Controller SW2 DIP Switch Settings
Switch
Number
SW2-1
SW2-2
SW2-3
SW2-4
SW2-5
SW2-6
SW2-7
SW2-8
NOTE:
Function
Position
Normal
Operating
Position
0 = Off
Off - Must be
1 = On
Allow Power Supply Enable on
0 = Off
Off - Must be
Cooling FLT
1 = Allow
Allow Power Supply Enable on
0 = Off
Off
RFL PWR FLT
1 = Allow
0 = 220
System
High Voltage Supply Range
1 = 440
dependent
0 = J112
Reflected Power RF Source
1 = J114 (If not
System
Externally Diplexed) dependent
Allow Power Supply Enable on
0 = Off
Off
Reject Load Faults
1 = Allow
0 = Off
Reserved for Factory Test
Off - Must be
1 = On
0 = Off
Reserved for Factory Test
Off - Must be
1 = On
These switch positions are factory set and should not be changed.
Reserved for Factory Test
Volume 2, Rev. 0
2-16
Off
Off
Off
Off
Innovator HXB Series Digital
UHF Transmitter
Chapter 2, Amplifier Cabinet
2.4.4: Cooling Blower Control
The cabinet controller board provides
signals that can be used to operate a
cabinet cooling blower relay. On the
board, Pin 16 provides +5VDC through a
0.5 amp self-resetting fuse. J125 pin
20, on the board, provides an opendrain connection for cabinet cooling
blower control. Pin 19 provides +12VDC
through a 0.5 amp self-resetting fuse.
These two connections are wired to the
Terminal Block TB1 located in the rear,
right side, near the top of the amplifier
cabinet. TB1-1, +12VDC, and TB1-3,
Blower Control, need to be connected by
22AWG wire to the Fan Control Board
mounted in the blower cabinet to
operate the Blower.
2.4.5: Cabinet Controller Problem Resolution Guide
Table 2-3: Cabinet Controller Assembly Problem Resolution Guide
Condition
Possible Cause
• One of the three AC input phases may not be present or at least one
may be low in voltage.
• Serial communication with the cabinet controller may not be
operational thus, the amplifiers and power supplies are remaining in
their last state.
Transmitter is
enabled but
either the
Amplifiers and/or
the Power
Supplies are not
enabled.
• Reject load levels of an UHF system may be greater than the
programmed fault threshold.
• If two or more amplifier modules report an over temperature
condition, all amplifiers are placed into standby and the fault is
latched until the cabinet is placed into standby mode.
• High voltage power supply SCR controller(s) may not be operational.
• Amplifiers are not enabled until the power supplies are enabled for
five seconds.
• Cabinet Controller internal DIP switch position one may be in the ON
position. This position causes the controller to ignore serial
communication commands thus the amplifiers and power supplies are
remaining in their last state.
• If tripped, reset the 110 VAC circuit breaker(s) of the ±15 VDC
supply(s) located in the lower front of the control cabinet. If
redundant power supplies are installed, the system will operate if only
one supply is operational. Diodes located in the cabinet controller
prevent one supply from disabling the second power supply.
All LEDs of
Amplifier
Modules are Off.
• Determine if the ±15 VDC supply located in the lower front of the
control cabinet has valid input and output levels. WARNING: THE
HIGH VOLTAGE SUPPLY LINES ARE LOCATED BEHIND THE FRONT
COVER. REMOVE POWER FROM THIS AREA BY LOCKING OUT THE
HIGH VOLTAGE FEEDS TO THE AMPLIFIER CABINET.
• Disconnect and pull each amplifier module forward a few inches to
disengage it from the supply connector. Determine if one amplifier
may be the source of the problem. Each amplifier is powered through
a self-resetting 0.5 amp fuse.
Volume 2, Rev. 0
2-17
Innovator HXB Series Digital
UHF Transmitter
Chapter 2, Amplifier Cabinet
Table 2-3: Cabinet Controller Assembly Problem Resolution Guide - Continued
Condition
Possible Cause
•
The module status LED is blinked to show various fault states:
Blinks Fault
Type
3 Fault w/ 5 second min and 5 Minute
Pallet(s) Over Current
Retest
Over Temperature
1 Fault with 5 Minute Retest
High Power Supply Over
1 Fault without retest. Requires standby
Voltage
to clear.
High Power Supply
3 Fault w/ 5 second min and 5 Minute
Under Voltage
Retest
3 Fault w/ 5 second min and 5 Minute
Reflected Power Fault
Retest
+12 VDC Supply Fault
Faulted only while supply is out of range
3 Fault w/ 5 second min and 5 Minute
Overdrive Fault
Retest
Amplifier
Module
Status LED
is blinking.
(LED located
nearest to
the amplifier
NOTES: 3 Fault means that if the fault occurs three times within 30 seconds, the
handle.)
fault is latched.
5 second min means that the fault is held for a minimum of 5 seconds.
A 5 Minute Retest means that the fault is held active for five minutes.
After five minutes, the fault is cleared and the amplifier is re-enabled.
If the amplifier module is placed in standby, fault counters and latched
states are immediately cleared thus allowing the system to return to
operate mode.
• Verify amplifier module is fully seated in amplifier chassis.
• If entire amplifier cabinet is not responding, check serial cable between the
amplifier cabinet and transmitter system controller.
Amplifiers or
Cabinet
Controller
not
reporting on
transmitter's
System
Controller
• If multiple amplifier cabinets are present, disconnect cable from first amplifier
cabinet to second cabinet. If communication resumes, reconnect the serial
cable and remove the next amplifier cabinet serial cable. Continue through the
system until the source of communication error is identified.
• Exchange amplifier module with another position in the system. If the error
travels with the amplifier module, it needs serviced. If the error remains in
the same position, either the amplifier cabinet wire harness has been damaged
or the cabinet controller board has been damaged. If the problem does not
return when the amplifier modules are exchanged, a software update may be
needed for either the cabinet controller or the amplifier module(s).
• Does amplifier respond to serial operate and standby commands. If so, a
software update may be needed for the amplifier module(s).
Cabinet
Controller
reports a
reflected
power fault.
• Verify that the cabinet reflected power fault threshold is not set too low.
• If possible, use J114 for visual reflected power fault monitoring. This problem
should only occur on cabinet controller boards 1305306 version A and B.
Volume 2, Rev. 0
2-18
Innovator HXB Series Digital
UHF Transmitter
Chapter 2, Amplifier Cabinet
2.5: Functional Description of the
Amplifier Cabinet
2.5.2: Test Signal Evaluation
The RF samples test voltages are passed
to the control board of the amplifier for
internal evaluation and partly for
interrogation by the control unit. The
test values for the forward power at the
amplifier outputs are passed to the
control unit.
2.5.1: Signal Path
The RF signal delivered by the exciter
(≈+27 dBm) is connected through RG55 cable to the amplifier cabinet and
distributed to the inputs of the power
amplifiers (PAs) through one 2 way
splitter, then two 3 or 4 way splitter
panels. The top 3 or 4 way panel
supplies the RF to the top 3 or 4
amplifier trays and the bottom 3 or 4
way panel supplies RF to the bottom 3
or 4 amplifier trays.
The following test points are available
for external measuring equipment or
transmitter control equipment:
The power amplifier tray is a three-stage
design comprised of a predriver (≈9 dB
gain), a driver (≈18 dB gain), and the
final stage (≈18 dB gain). The RF signal
(≈15 dBm ATSC) is first preamplified in
the predriver, which is part of the
phase/gain board (≈24 dBm), and driver
(≈42 dBm) before it is passed through a
coupler board to the splitter where it is
split four ways (≈36 dBm) and
distributed to the four final-stage
modules. The outputs of the final stages
(≈54 dBm) are summed in a combiner.
The output of the combiner (≈58.9 dBm)
connects to a directional coupler that
couples out voltages proportional to the
forward and reflected power at the
output of the amplifier. The output of
the amplifier tray is typically +58.9 dBm
ATSC. The coupler also provides a
forward power sample that is passed to
J3 on the front panel to provide an RF
sample for test purposes. The same
coupler also supplies a voltage
proportional to the forward power from
the driver stage, which is used in the
monitoring and control circuitry. In
addition, the reflected power at the
amplifier output is monitored in the
control board of the amplifier and, if the
set threshold value is exceeded, the
operating voltages for the predriver and
driver are switched off and a fault
indication of the high reflected condition
is stored.
Volume 2, Rev. 0
2-19
•
RF test point at the amplifier outputs
at “N” connector (J3).
•
RF test points at the output side of
the amplifier through a directional
coupler downstream of the cabinet
combiner.
2.5.3: Regulation of Transmitter
Output Power
The regulation of output power takes
place in the Digital Exciter. The actual
value for the automatic level control
(ALC) is taken from test voltages in the
amplifier trays that are dependent on
the output power of each individual tray.
If an amplifier fails, transmitter
operation continues at reduced output
power. In order to prevent the ALC
from correspondingly increasing the
output power of the Digital Exciter
during reduced power operation, the
test outputs of the individual amplifiers
are circuited in parallel so that only the
test voltage of the amplifier that delivers
the highest output power is used in the
ALC control loop.
2.5.4: Fault Protection Circuitry
The amplifiers possess fault protection
circuitry, which, if necessary, initiates
the switching Off, of the respective unit
and simultaneously issues a fault
indication to the control unit.
The protective circuits in the amplifiers
monitor the following values:
Innovator HXB Series Digital
UHF Transmitter
•
•
•
•
Chapter 2, Amplifier Cabinet
•
•
•
•
•
Drain currents of the final stage
transistors
Operating voltage
Temperature
Reflected power at the output
480/208 VAC Mains phase
Primary voltage
Primary current
Output voltage
Temperature
2.5.5: Capture of Operating Values
in the Amplifiers
If a threshold value is exceeded, the
amplifier shuts down. Following a oneoff fault, the amplifier automatically
switches on again after a delay of about
1 second. When repeated faults occur
(more than 5 within 10 seconds), the
amplifier switches on again after a delay
of 5 minutes. In addition, the amplifier
can be switched on, at any time, by a
command from the transmitter control.
The following operating values are
captured and processed in the amplifier
control board and prepared for
transmission to the exciter/control
cabinet controller.
•
•
•
•
•
The protective circuits in the power
supply units monitor the following
values:
• 480/208 VAC Mains voltage
Drain currents of the final-stage
transistors
Operating voltage
Temperature
Forward power at the output
Reflected power at the output
2.5.6: Amplifier Cabinet Connections
RF Input to S Input on the
(A14) 2 Way Splitter
(1.8kW or 5kW) or to the
X5 input jack on the (A16)
4 Way Splitter Panel
(2.5kW) or (A16) 3 Way
Splitter Panel (1.8kW)
RF Output
3-1/8” EIA
Figure 2-10: Amplifier Cabinet Connections
Volume 2, Rev. 0
2-20
Innovator HXB Series Digital
UHF Transmitter
Chapter 2, Amplifier Cabinet
Table 2-4: Amplifier Cabinet Connections
Connector
S on (A14) 2 Way Splitter (1.8kW or 5kW) or to the
X5 input jack on the (A16) 4 Way Splitter Panel
(2.5kW) or (A16) 3 Way Splitter Panel (1.8k)
RF O/P of (A25) Combiner
2.6: Service
Work on the amplifier cabinet must only
be performed by trained personnel. Take
note of the following precautions:
3-1/8 EIA
Figure 2-11: Labeling of Toxic
Substances in Drawings
2.6.2: Test Point Evaluation
Various RF test points in the signal path
in the amplifier cabinet are available for
evaluation and can be polled and
displayed through the control unit. RF
test points for external measuring
equipment are also available at the
amplifiers and the directional coupler at
the output of the amplifier cabinet.
2.6.3: Display of Operating Values
Aside from RF powers, the following
operating values can be polled and
displayed in the transmitter control unit:
•
2.6.1.1: Labeling of Dangerous
Substances
Components containing substances
dangerous to health are labeled as such.
The label is either glued on the
Volume 2, Rev. 0
RF Output
Berylliumoxid
The amplifier cabinet is maintenance
free; however, in order to ensure
trouble-free operation, it must be
checked and serviced at regular
intervals, taking into account the local
environmental conditions. Operational
reliability depends on proper service.
This is especially relevant when checking
grounding and power connections.
Carry out all work with extreme
caution.
RF SMA-type
female connector
BeO
2.6.1: Safety Information
•
RF Input
In drawings (e.g., component layouts of
PC boards) and circuit diagrams, parts
containing toxic substances, such as
beryllium oxide (BeO), are labeled as
shown in Figure 2-11.
The amplifiers are factory aligned and
can be inserted in the cabinet without
the need for retuning or adjustment.
Before working on or removing a
component, make sure that it is
isolated from power.
Type
component itself or in its immediate
vicinity.
The amplifier cabinet is user-friendly and
designed for operational safety. The
paralleling networks in the cabinet
ensure that if an amplifier fails or is
removed, transmitter operation
continues at reduced power without
degradation of performance.
•
Assignment
2-21
•
•
•
•
Forward & Reflected power at the
output of the amplifiers
Amplifier operating voltage
Amplifier currents
Amplifier temperatures
Forward power at the output of the
amplifier cabinet
Innovator HXB Series Digital
UHF Transmitter
AMP#1
AMP#2
AMP#3
AMP#4
A17
A18
A19
A20
Chapter 2, Amplifier Cabinet
(PS#1)
(PS#1)
(PS#1)
(PS#1)
MODULE OK LED
ENABLE LED
ENABLE LED
AMP#5
AMP#6
AMP#7
AMP #8
A21
A22
A23
A24
MODULE OK LED
(PS#2)
(PS#2)
(PS#2)
(PS#2)
POWER SUPPLY #1 CIRCUIT
BREAKER FOR TOP AMPLIFIERS
±12V POWER SUPPLY
RESET BREAKERS
POWER SUPPLY #2 CIRCUIT
BREAKER FOR BOTTOM AMPLIFIERS
Figure 2-12: Location and Assignment of the Circuit Breakers and LEDs
2.7: Exchange of an Amplifier Tray
#2 for the bottom four Amplifier
assemblies, may be isolated from main
AC power by switching off the
appropriate front panel circuit breaker.
This is accomplished by tripping the
respective breaker located on the circuit
breaker assembly panel, at the bottom
of the amplifier cabinet. Disconnect the
RF cables.
For reasons of safety, amplifier trays
MUST be in standby (RF disabled)
before any connections are removed. If
the amplifier control board is loaded
with software version 2.4 or high, an
Axcera Amplifier disable plug (1308219)
can be used to place an individual tray
in standby. If your amplifier tray has a
front panel disable switch, this switch
can be used to disable the amplifier.
Regardless of the version of code, any
power amplifier may safely be removed
by disabling its power supply. The
power supply, either the top power
supply #1 for the top four Amplifier
assemblies, or the bottom power supply
Volume 2, Rev. 0
NOTE: To prevent damage to the tray,
you must first disconnect the Input
Cable and then disconnect the Output
Cable.
2-22
Innovator HXB Series Digital
UHF Transmitter
Chapter 2, Amplifier Cabinet
Caution: The amplifier weighs
approximately 60 pounds. Use
extreme care when removing it from
the cabinet.
Undo the two holding, fixing, screws and
pull the amplifier out to the end stop.
Find and release the mechanical lock,
located on the bottom of the top four
amplifier trays and on the top of the
bottom four amplifier trays. See Figure
2-13. Pushing the release down on
bottom amps and up on top amps
releases the catch. Carefully pull the
amplifier completely out of the cabinet
assembly.
should be installed in the slot where the
amplifier assembly was removed and a
fake front panel should be installed on
the cabinet. This is to insure proper air
flow through the cabinet and cooling of
the remaining amplifier trays.
Connect the RF cables. NOTE: You
must connect the Output Cable first and
then connect the Input Cable.
Engage the respective circuit breaker,
Power Supply #, 1 for amplifiers (1-4,
A17-A20) or Power Supply #2, for
amplifiers (5-8, A21-A24).
Amplifier Adjustments
There are no customer adjustments.
Lock
Information on a Change of Channel
Frequency
The following work must be carried out
at the amplifier cabinet when changing
the channel frequency:
Figure 2-13: Amplifier Tray Lock
Location
Caution: After the amplifier is pulled
out, a high voltage may still be
present at its output.
Insert and secure the new amplifier.
Note the vertical position of the amp
tray, do not try to insert upside down.
Carefully push the amplifier into the rear
connectors making certain that solid
connection is made.
NOTE: If a replacement amplifier is not
available, then an Air Blocking Plate
Volume 2, Rev. 0
2-23
•
The length of RF cables between the
splitters and the amplifiers needs to
be altered.
•
The coupling attenuation needs to be
checked.
•
The output powers of the amplifiers
must also be checked.
NOTE: It may be necessary to make
further adjustments at other cabinets
and assemblies in the transmitter when
a change in channel frequency is made.
Innovator HXB Series Digital
UHF Transmitter
Chapter 3, UHF Amplifier Tray and
Cabinet Assemblies Circuit Descriptions
Chapter 3:
UHF Amplifier Tray Assembly and Cabinet Assemblies
Circuit Descriptions
3.1: Amplifier Tray Assembly
Overview
RF output of the individual amplifier tray
assembly.
Each UHF amplifier tray assembly serves
to amplify the RF signal delivered by the
exciter to the power level needed to
attain the full rated output power of the
transmitter. Nominal transmitter output
power is achieved by adding the parallel
connection of individual amplifier tray
assemblies, within a cabinet assembly,
and then the adding of a number of
multiple amplifier cabinets.
The features of the UHF amplifier tray
assembly include:
•
•
•
•
•
The amplifier operates over the UHF TV
frequency spectrum without any special
tuning requirements. It is a three-stage
amplifier design formed by a predriver,
mounted on the phase/gain board,
driver, and final stage as shown in
Figure 3-1. The driver is a single stage
amplifier module whose output is split
four ways. The final stage is made up of
four identical power modules. The four
outputs are connected to a 4-way
combiner assembly whose output is the
•
All amplifying stages are equipped
with transistors
Operates over the UHF frequency
band without special tuning
requirements
High redundancy due to the parallel
connection of many power transistors
Mean junction temperature <120° C.
Important operating parameters,
such as drain currents, operating
voltages, RF powers, and
temperatures are polled and
displayed in the transmitter control
assembly.
The amplifier possesses multiple
fault-protection circuits that prevent
damage to the power transistors
during critical operating conditions,
such as high mismatch,
overtemperature, over-current, or
over-voltage.
Figure 3-1: UHF Amplifier Assembly
Volume 2, Rev. 0
3-1
Innovator HXB Series Digital
UHF Transmitter
Chapter 3, UHF Amplifier Tray and
Cabinet Assemblies Circuit Descriptions
The paralleling network of the amplifier is arranged so that it continues to operate at
reduced power if a module fails. The remaining available power is given by:
Prem = Pnom ⋅ ([m - n] / m)2
where:
Prem = remaining power
Pnom = nominal power
m = number of modules
n = number of failed modules
Figure 3-2: Remaining Power after Failure of Amplifier
Modules
3.2: Design of the UHF Amplifier
All RF connectors are located on the
front panel, while the control and power
connectors are mounted at the rear
panel. The amplifier control board is
mounted vertically behind the front
panel. Two LEDs, Module OK and
Enable, are mounted on the amplifier
control board and are visible through the
front panel, indicate the operating status
of the amplifier tray.
The amplifier tray assembly is designed
as a slide-in unit. The mechanical
support structure is formed by a finned
heat sink on which the individual
assemblies are mounted. The amplifier
assemblies are listed in Table 3-1.
Position
A14
A1
A2
A12
A4
A5 to A8
A13
A17
Table 3-1: Assemblies in the UHF Amplifier Tray
Assembly
Remarks
Amp Control Board
For control, monitoring, and test signal capture
Provides phase and gain control of the RF through
Phase/Gain Board
the tray and also acts as a Predriver, (≈9 dB gain).
Dual BLF871 Amplifier
Driver power amplifier to the splitter, (≈18 dB gain).
Module Assembly
Provides Driver forward, final amplifier peak and
Coupler Board
average forward and reflected power samples.
Distributes the RF input from the coupler board to
Splitter (1:4)
the final amplifier pallets A5 to A8, (≈36 dBm).
Four final amplifier boards with ≈18 dB gain and an
UHF Pallet Boards,
Broadband BLF878
output of ≈54 dBm.
Sums the amplified outputs of the 4 UHF Pallet
Combiner (4:1)
Boards. (≈58.9 dBm Output)
Takes the three +48VDC inputs and switches them
FET Switch/Metering
to the predriver, driver and the amplifier pallets. In
Board
addition, the forward and reflected metering
samples connect through the board.
Volume 2, Rev. 0
3-2
Innovator HXB Series Digital
UHF Transmitter
Chapter 3, UHF Amplifier Tray and
Cabinet Assemblies Circuit Descriptions
A12 Coupler Board
J2
RF Output
J3
RF Sample
A14
Amplifier
Control Board
A2 Dual BLF871
Amplifier
Assembly
A1
Phase/Gain
Board
A13 4 Way
Combiner
Board
A13
A12
A2
A8
A7
A6
A5
A5, A6,
A7, A8
UHF Pallet
Boards
A4 4 Way
Splitter
Board
A1
A4
J1
RF Input
Figure 3-3: Location of the Assemblies in the UHF Amplifier
The amplifier is a three-stage design
with a predriver, mounted on the
phase/gain board, a dual BLF871
amplifier driver pallet and four UHF
BLF878 amplifier pallet final stages.
(See Figure 3-3)
to the forward powers at the input to the
4 way splitter and at the output of the 4
way combiner. The directional coupler
also provides a detected voltage
proportional to the reflected power at
the output of the 4 way combiner. These
test voltages are passed to the amplifier
control board, mounted behind the front
panel, for internal evaluation and partly
for interrogation by the control unit. In
addition, the reflected power at the
amplifier output is monitored in the
amplifier control board and if the
threshold value is exceeded, the
operating voltages for the predriver and
driver are switched off and a fault
indication is stored. The output coupler
also supplies a signal proportional to the
forward power at the output of the 4
way combiner, which is connected to J3,
located on the front panel, for testing
purposes.
The RF input signal (≈+15 dBm ATSC) is
fed to the amplifier through connector J1
on the front panel. The signal is
preamplified by the (A1) phase/gain
board (predriver) (+24 dBm), amplified
by the (A2) dual BLF 871 amplifier
module (driver) (+42 dBm) before it is
passed through the (A12) coupler
assembly to the (A4) 4 way splitter
(+42 dBm). The outputs of the splitter
(+36 dBm) are distributed to the four
UHF amplifier pallets BLF878 (A5 - A8).
The outputs of each of the final stage
modules (+54 dBm) are combined in the
(A13) 4 way combiner and the resultant
signal is passed through the (A12)
coupler board to the RF output
connector J2 (≈+58.9 dBm ATSC).
Test voltages derived from the forward
power of the amplifier are generated in
the amplifier control board to provide
automatic level control (ALC) in the
exciter stage of the transmitter. The
ALC is a function of the rms value of the
output power.
The outputs of the predriver and the 4
way combiner connect through the
(A12) directional coupler. The coupler
supplies detected voltages proportional
Volume 2, Rev. 0
3-3
Innovator HXB Series Digital
UHF Transmitter
Chapter 3, UHF Amplifier Tray and
Cabinet Assemblies Circuit Descriptions
Figure 3-4: Block Diagram of the UHF Amplifier
The amplifier trays can be replaced
during transmitter operation and no new
alignment work is necessary. The
frequency-dependent operating
parameters for the complete frequency
range are stored in the controller and
are automatically enabled by the
frequency setting of the exciter. The RS
232 port is used for the factory
alignment of operating parameters, e.g.,
calibration of RF and drain current test
values.
monitored in the control board and, if a
fault condition arises, the operating
voltage for predriver mounted on the
phase/gain board A1 and driver A2 is
disconnected by the action of field effect
transistors mounted on the A17 FET
switch metering board. The fault
indication is stored and passed to the
control unit.
The measured values of the temperature
sensors (A15), mounted on the front of
the driver amplifier, and (A16), mounted
on the rear of the final amplifier, are
passed to the control board where they
are monitored and available for
interrogation by the control unit.
The operating voltage Uop of +48 volts is
distributed to the final amplifier modules
by a current bus underneath the
combiner. In addition to Uop for the
modules, the amplifier requires auxiliary
voltages of ±12 volts for the amplifier
control board. The operating voltage
and current consumption of the
individual modules are captured in the
combiner board and passed to the
control board where they are available
for interrogation by the control unit.
Furthermore, threshold values are
Volume 2, Rev. 0
The amplifier control board possesses a
number of LEDs that indicate the status
of the amplifier. Two of these LEDs are
visible through the front panel. The
green Module OK LED indicates faultfree operation. The Green Enable LED
indicates that the enable is applied to
that assembly. It will not be lit if the
3-4
Innovator HXB Series Digital
UHF Transmitter
Chapter 3, UHF Amplifier Tray and
Cabinet Assemblies Circuit Descriptions
3.2.1: Capture of Test Values in the
UHF Amplifier Tray Assembly
Enable is removed. It will be lit Amber if
the Enable is applied but the amplifier is
not operating.
The following test values are passed to
the transmitter control unit:
A fault condition is indicated by a Red
Module OK, either continuously
illuminated or flashing Red. The flashing
Red LED interprets as follows:
•
•
Table 3-2: Module OK LED Red and
Blinking interpretation
Red
LED
Blinking
1 Blink
2 Blinks
3 Blinks
4 Blinks
5 Blinks
6 Blinks
7 Blinks
•
•
•
Meaning
Indicates Amplifier Current Fault
Indicate Temperature Fault
Indicate Power Supply Over Voltage
Fault
Indicate Power Supply Under
Voltage Fault
Indicate Reflected Power Fault
Indicate +12V or –12V Power
Supply Fault
Indicate AGC Overdrive
Forward power at the amplifier
output – rms output power
Reflected power at the transmitter
output – peak level
Operating voltage
Current consumption of the modules
Temperatures
The following test values are used only
for internal purposes on the control
board:
•
Forward driver power A2 (not
displayed in the control unit)
The following test points are available
for external equipment:
•
•
RF Output Sample test jack J3 on the
front panel.
Output power (A2) driver module
(Used for factory measurements
only.)
Figure 3-5: Interconnect Typical UHF Amplifier Assembly
Volume 2, Rev. 0
3-5
Innovator HXB Series Digital
UHF Transmitter
Chapter 3, UHF Amplifier Tray and
Cabinet Assemblies Circuit Descriptions
3.2.2: Functional Description of the
Boards in the UHF Amplifier Tray
Assembly
ATSC, which is applied to the Directional
Coupler U31. The direct RF output of
the coupler, ≈+24 dBm, connects to J4
the RF output jack of the board. The
coupler also supplies a signal to the
comparator IC U32, that compares the
output level sample with a fault
threshold setting and produces an
overdrive fault, OD FLT, if the signal
increases above the preset level. The
OD FLT is connected to the flip-flop IC
U29, whose output connects to the high
speed PIN switch, cutting it back which
cuts back the output of the board and
therefore the tray.
3.2.2.1: (A1) Phase/Gain Board
(1311583; Appendix B)
This board is mounted in a Phase/Gain
Assembly (1311993). It performs a
variety of functions, such as amplifying
the incoming RF signal to the level
needed to drive the amplifier tray to full
power. It adjusts the phase shift
through the board so that parallel
amplifier trays combine correctly. The
board also contains protection circuitry
to quickly mute RF drive in the event of
an overdrive or reflected power fault.
Finally, it contains DC/DC converters
that generate various needed power
supply voltages for the board.
+42 VDC needed for operation of the
board connects to the board at J2-3 & 2
and is fed to the amplifier Q6 for biasing
and to the +24 VDC regulator IC U28.
The +24 VDC regulated output of U28 is
used by the IC U24 for biasing. +12
VDC connects to the board at J3-7 and is
fed to Q1 and U8 where it is used for
biasing the devices. The +12 VDC is
also connected to the +5 VDC regulator
IC U30. The regulated +5 VDC output is
fed to various parts of the board for use
in biasing and level control. -12 VDC
connects to the board at J3-8 and is fed
through voltage divider networks to U32
and U33 where the values are used to
set up reference levels to the devices.
The RF Input to the tray (+15 dBm ATSC)
is connected to the SMA Jack J1 located
on the phase/gain board. The RF is
applied to a PIN diode attenuator circuit
consisting of CR9, CR10 and the hybrid
coupler U6. This attenuator is used to
set the overall output level of the tray.
Increasing the voltage at TP2 will
increase the gain of the tray.
The output of the PIN attenuator circuit
drives a high speed PIN switch
consisting of CR7, CR8 and associated
components. This switch is used to
remove RF drive quickly in the event of
a fault. The switch is controlled by a
mute command from the Amplifier
Control Board.
3.2.2.2: (A2) Dual BLF871 Amplifier
Board (1311578; Appendix B)
This board is mounted in a Dual BLF871
Amplifier Module Assembly (1311991).
This board consists of a two single stage
amplifiers operating in parallel. The
board has an overall gain of
approximately 18 dB. The RF input to
the board connects to U3 a hybrid
splitter which produces two equal
outputs. One output of the splitter is fed
thru a matching and response network
to the gain stage, which consists of the
LDMOS transistor Q1 operating in Class
AB. C11 is adjustable for best response.
The bias voltage for the transistor is
generated from +42VDC that connects
through the resistor R3 to the drain on
The output of the PIN switch drives a
phase shifter circuit consisting of hybrid
coupler U25 and its associated
components. The phase shifter has a
range of about 135° which adjusts the
output phase of the tray to the required
value for best combining of multiple
amplifier trays.
The output of the phase shifter, RF_A, is
connected to a LDMOS amplifier, Q6,
which amplifies the RF output signal to
an approximate level of +24 dBm for
Volume 2, Rev. 0
3-6
Innovator HXB Series Digital
UHF Transmitter
Chapter 3, UHF Amplifier Tray and
Cabinet Assemblies Circuit Descriptions
Q1 and through the voltage regulator
U1. The regulated voltage at the output
of U1 is adjusted with the pots R7 and
R6 before it is connected to the drain on
Q1. The Diode CR1 provides
temperature compensation for the
transistor. The transistor is capable of
producing an output of over 20 Watts
ATSC. The amplified output is
connected thru a matching network to
one input of U4 a hybrid combiner.
connected to J3-5 as the forward driver
power sample metering output.
Another RF input from the output of the 4
way combiner board connects to jack J4.
The RF is connected by a strip line track
to the RF Output jack J2 that connects to
the front panel RF output jack, J2 which
is the RF output for the UHF amplifier
tray. Three hybrid coupler circuits in the
RF output path on the coupler board pick
off power samples, two forward samples
and one reflected sample. One forward
sample connects to a divider network that
splits the output. One output is
connected to the detector IC U1 whose
output is peak detected by U2 and
associated circuitry and amplified by U3A
to produce the final amplifier peak
metering output at J3-2 that connects to
the FET switch metering board. The
other output of the divider network is
connected to the detector IC U4 whose
output is amplified by U3B and connected
to J3-1 the average power metering
output that connects to the FET switch
metering board. The other forward
sample connects through J1 on the board
that is cabled to the RF sample jack J3
located on the front panel of the amplifier
tray, which can be used for test purposes.
The reflected sample of the RF output
connects out of J10 on the board to the
amplifier control board.
The other output of the input splitter is
fed thru an identical amplifier circuit as
described for the Q1 transistor, except it
is for the Q2 transistor. C45 is
adjustable for best response, R16 and
R17 are the bias adjustment pots and
CR2 is the temperature compensating
diode for the Q2 amplifier circuit. The
amplified output of Q2 is connected thru
a matching network to the other input of
the U4 hybrid combiner. The hybrid
combiner combines the two amplified
outputs of the Q1 and Q2 LDMOS
devices and produces a single RF output
(≈+42dBm) of the board and the
assembly, which a cabled to the (A12)
Coupler Board.
3.2.2.3: (A12) Coupler Board
(1311882; Appendix B)
The UHF coupler board assembly provides
forward power samples of the output of
the (A2) Dual BLF871 amplifier module
assembly and also the output of the
(A13) 4 way combiner. It also provides a
reflected sample of the output of the
(A13) 4 way combiner. The forward
samples connect through the FET switch
metering board to the amplifier control
board where they connect to the
overdrive protection circuit. The reflected
sample connects directly to the amplifier
control board.
3.2.2.4: (A4) 4 Way Splitter Board
(1306371; Appendix B)
The (A4) 4-way splitter splits the output
signal (+42 dBm ATSC) of the driver
module assembly (A2) that was coupled
through the (A12) coupler board to J1
on the splitter board. These four
outputs connect to the four parallel UHF
Pallet Boards (A5 - A8).
The splitter circuit is in the form of micro
strips mounted on a Teflon board. The
actual splitter network does not
incorporate tuning elements. The
network provides for an equal splitting,
over the frequency range of the UHF
band, of the input RF signal at the
connector J1. The input signal is first
The RF input to the UHF coupler
assembly, from the Dual BLF871
Amplifier assembly, connects to jack J9.
The RF is fed thru a strip line track to the
RF Output jack J8 that is cabled to the 4
way splitter. A hybrid coupler circuit
picks off a power sample that is
Volume 2, Rev. 0
3-7
Innovator HXB Series Digital
UHF Transmitter
Chapter 3, UHF Amplifier Tray and
Cabinet Assemblies Circuit Descriptions
split in a ratio of 1:2. After this, both
partial powers are split in a second stage
in the ratio of 1:2. The load (balancing)
resistor of the initial 1:2 stage is formed
by the series connection of a 100Ω/10W
power resistor. The balancing resistors
of both secondary 1:2 stages are also in
the form of 100Ω/10W resistors. Each of
the four outputs of the splitter board is
typically +36 dBm in level.
FET, configured in a push pull
arrangement, with approximately 16 dB
of gain. The amplified outputs of the
FETs connect to a Balun assembly that
combines the two 180° out of phase
signals into a single -90° output. The
-90° output connects to one input of the
output hybrid combiner circuit.
The 0° signal is applied to a Balun
assembly that produces two 180° out of
phase outputs. The two outputs connect
to Q2 a dual FET, configured in a push
pull arrangement, with approximately 16
dB of gain. The amplified outputs of the
FETs connect to a Balun assembly that
combines the two 180° out of phase
signals into a single 0° output. The 0°
output connects to the other input to the
output hybrid combiner circuit.
3.2.2.5: (A5-A8) UHF Broadband
Pallet Board, BLF878
(1313170; Appendix B)
The (A5, A6, A7 & A8) UHF Pallet Dual
Stage Amplifier Boards provide
approximately 18 dB of gain each.
This board is a LDMOS UHF power
amplifier consisting of two parallel power
transistor stages operating in parallel.
The amplifier operates on a power
supply voltage of +42 VDC supplied to
the board from the FET switch metering
board. The voltage regulator U1 steps
down the voltage to provide a bias
voltage to the transistors. The diodes
CR1 for Q2 and CR3 for Q1 are used to
temperature compensate the bias
voltages. As the RF transistors heat up,
the associated diode also heats up,
causing the voltage across it to drop,
lowering the bias voltage to the RF
transistor so that the biasing remains
constant with device temperature
changes.
The 0° and the -90° signals are combined
by the output hybrid combiner circuit and
connected to J2 the RF output jack on the
board (≈+54 dBm).
The +42 VDC, from the FET switch
metering board, connects to J3 on the
board. The voltage is applied through the
resistors, R24 to Q2 and R31 to Q1, and
the Baluns to the drains of the devices.
The +42 VDC is also connected to the
regulator IC U1 that supplies the source
voltages through the Baluns to Q1 and
Q2. R26 & R27 for Q2 and R42 & R43 for
Q1 are adjusted at the factory to set up
the optimum drain currents of the devices
and should not be readjusted.
The transistors are operated in
quadrature, with one transistor pair
operating 90 degrees out of phase of the
other pair, which provides for a very
good return loss across the UHF band on
both the input and output of the board.
3.2.2.6: (A13) 4 Way Combiner
Board (1311945)
The (A13) 4-way combiner combines the
output signals of the UHF broadband
amplifier pallet boards typically +54
dBm into a single output typically +58.9
dBm ATSC, which connects through the
coupler board to the output jack for the
tray at J2.
The RF input at a level of approximately
+36 dBm connects to J1 on the board.
The input is applied to a hybrid splitter
that produces two outputs, one at 0° and
one at -90°. Each output connects to
identical circuits. The -90° signal is
applied to a Balun assembly that
produces two 180° out of phase outputs.
The two outputs connect to Q1 a dual
Volume 2, Rev. 0
The combiner circuit is in the form of
Baluns mounted on a Teflon board. The
actual combiner network does not
incorporate tuning elements. The
3-8
Innovator HXB Series Digital
UHF Transmitter
Chapter 3, UHF Amplifier Tray and
Cabinet Assemblies Circuit Descriptions
network provides for equal combining,
over the entire UHF band, of the four
inputs at connectors J4-J7. The signals
at J4 and J5 are combined at a ratio of
2:1 and the signals at J6 and J7 are
combined at a ratio of 2:1. After this,
both combined powers are combined
again in a second stage in the ratio of
2:1. The load (balancing) resistors of
the first two 2:1 stages are 50Ω/250W
power resistors, and for the second
stage 2:1 stage is a 50Ω/350W power
resistor. The combined RF output of the
board is at J2 and is typically +58.9
dBm 775 Watts ATSC in level.
The FET switch/metering board will
remove the +40 VDC from the amplifier
boards during hot replacement of the
UHF Amplifier Tray Assembly. The FETs
Q1, Q2 and Q3 are controlled, switched
On and Off, by the high power gate
control that is applied to J15-25 from
the Amplifier Control Board. The drain
currents of the power transistors
mounted on the UHF broadband
amplifier pallet boards are captured by
.005Ω precision resistors connected in
their supply lines. The voltage drops
across these resistors are passed to the
amplifier control board through two
43.2kΩ bleeder resistors in parallel. In
addition, the +40 VDC operating voltage
at J15-12 is also passed to the amplifier
control board for monitoring purposes.
3.2.2.7: (A17) FET Switch/Metering
Board (1312342; Appendix B)
The FET switch/metering board provides
protection of the +40 VDC to the
amplifier modules in the tray, feed
through connections of the driver and
final amplifier forward power samples
and feed through connections of the
temperature sensors A15 and A16
mounted on the heatsink assembly.
Critical operating parameters, including
current high or low and the temperature,
of the amplifiers are monitored on the
amplifier control board through the FET
switch metering board. If threshold
values are exceeded, the amplifier
control board switches Off the operating
voltages for the predriver, driver and
final amplifiers using the high power
gate control that turns Off the FETs Q1,
Q2 and Q3 on the FET switch metering
board.
The (A12) coupler board provides
voltages proportional to the peak and
average forward output power of the 4
way combiner. These test voltages are
coupled through and passed to the
amplifier control board through J15-2 for
average output power and J15-14 for
peak output power. A sample of the
(A2) Dual BLF871 driver amplifier
assembly forward power connects
through the FET Switch/Metering Board
at J15-1 that is supplied as a driver
forward power sample to the amplifier
control board.
3.2.2.8: (A14) Amplifier Control Board
(1311683; Appendix B)
All protective, switching, display, and
monitoring functions required for the
operation of the UHF amplifier tray
assembly are realized by the amplifier
control board. The amplifier control
board is mounted vertical in a RF
enclosure behind the front panel of the
amplifier tray. The amplifier control
board performs the following tasks:
3.2.2.7.1: Operating Voltages for the
Amplifier Boards
The operating voltage of +40 volts is
distributed to each of the UHF pallet
amplifier boards, TB4 to A8, TB3 to A7,
TB2 to A6, and TB1 to A5. The +40
volts is also distributed to the (A2) Dual
BLF871 amplifier assembly and the (A1)
phase/gain board TB5.
Volume 2, Rev. 0
•
•
•
•
3-9
Capture and processing of test
values
Fault protection for the amplifier
modules
Generating the actual value for
transmitter ALC
Communication with the transmitter
control unit
Innovator HXB Series Digital
UHF Transmitter
Chapter 3, UHF Amplifier Tray and
Cabinet Assemblies Circuit Descriptions
The circuits in the amplifier control
board do not contain elements that can
be adjusted. All of the required settings
are software implemented at the factory
during initial setup through a RS 232
port, located on the front panel of the
tray, and must not be altered.
through pin 9 of J1. NOTE: This pin is
usually not used unless hardware
handshaking is implemented.
3.2.2.8.1: Schematic Drawing
1311684 Page 1:
Located in the upper center of page one
of the schematic is U2, which is the
microcontroller. This in-circuit Atmel
microcontroller is operated at 3.6864
MHz. Programming of this device is
performed through J2. PF4 and PF5 are
analog inputs for ICs U33 and U34
located on page 4 of the schematic. The
desired analog channels of U33 and U34
are selected by the settings of PA0, PA1,
& PA2. PA3 of U2 drives a processor
operating LED, DS1, which is lit to show
continued operation. PF0 for +12V and
PF1 for -12V are used to monitor the
supplies to the board. PF3 is connected
to a via V3 for future access. PB3, 4, 5,
6 and 7 are used to indicate different
hardware revisions to the operating
software by placing a high, +5V, or a
Low, Ground, on the line.
U6 is a standard serial to RS-485 driver
IC. The resistor R25 sets U6 to transmit
mode when U2, the microcontroller, is
held in reset or PE2 is configured as an
input.
U4 is a watchdog IC used to hold the U2
microcontroller in reset if the supply
voltage is less than 4.21 VDC; {(1.25
VDC < Pin 4 (IN) < Pin 2 (Vcc)}. U4
momentarily resets the U2
microcontroller if Pin 6 is not clocked
every second.
U36 below U1 is used to reset faults that
are detected on Pages 2 and 5. Circuits
found on Pages 2 and 5 hold a fault
condition so that theU2 microcontroller
has enough time to detect the fault and
perform the necessary operation.
U5 is below U36 and is used to control
the board's status LEDs, DS3 Amplifier
Enabled and DS4 Module OK (See Table
3-3), and other circuits that are not
allowed to change state during a
microcontroller reset. The LEDs are
controlled by FETs, Q3-Q6, that when
the FET is turned on, it shuts current
away from the LED to turn it Off or when
the FET is turned off, current is fed
through the LED to turn it On.
U7 is located below U5 and is used to
transfer the latched fault conditions into
the microcontroller U2.
Table 3-3: DS4 Module OK LED Red and
Blinking interpretation
Red
LED
Blinking
1 Blink
2 Blinks
3 Blinks
4 Blinks
5 Blinks
6 Blinks
7 Blinks
U3 is a RS-232 serial port on UART 1 of
the U2 microcontroller. J1 is used to
provide front panel RS-232 access
(without hardware handshaking). A
standard NULL modem cable is needed
to connect to a PC. For test and debug,
all data into and out of the RS-485
interface of UART0 is transmitted
Volume 2, Rev. 0
U1, located in the Upper left corner of
the schematic, is used to determine
where the amplifier control board is
located. Module ID 1, 2 and 3 inputs
require an external pull-down to ground
to set the logic state but Module ID 4
requires an external pull-up. Diodes
such as CR1, located in the Module ID 1
line, found on Page 5 of the schematic,
prevent un-powered modules from
pulling down the Module ID lines of
other installed modules. The external
pull-down to ground connections are
made in the amplifier cabinet wiring
harness.
3-10
Meaning
Indicates Amplifier Current Fault
Indicate Temperature Fault
Indicate Power Supply Over Voltage Fault
Indicate Power Supply Under Voltage Fault
Indicate Reflected Power Fault
Indicate +12V or –12V Power Supply Fault
Indicate AGC Overdrive Fault
Innovator HXB Series Digital
UHF Transmitter
Chapter 3, UHF Amplifier Tray and
Cabinet Assemblies Circuit Descriptions
3.2.2.8.2: Schematic Page 2:
3.2.2.8.3: Schematic Page 3:
In the upper center section of page 2 are
circuits with ICs U35A, U35B, U11 and
U12. When the cabinet high power
supply is enabled, U35A generates a
regulated voltage that is approximately
7.5 Volts less than the +48 Volt high
power supply voltage. U11 and U12
generate a regulated voltage output that
is about 10 Volts higher than the high
power supply voltage. This voltage is
regulated to produce a voltage level that
is about 4.4 VDC above the high power
supply voltage. The PS +4.4VDC
regulated output is used to power the
unity gain op-amp circuits, U15, U17,
U19, U21 and U23, located on Page 3 of
the schematic.
Located on Page 3 there are four
identical current monitoring circuits for
checking the four output final amplifier
UHF pallet boards, BLF878. A 0.01 Ω
resistor is used within the amplifier tray
module for monitoring the current
through several sections of the amplifier.
The voltage developed across this
resistor is provided to the amplifier
control board through current limiting
resistors. The amplifier control board
also has two 43.2 kΩ current limiting
resistors mounted in parallel and a diode
on the inputs to the current monitoring
circuits. Due to the input bias current of
the Linear Technology LT1787HVCS8
precision high side current sense
amplifiers, U18, U20, U22 and U24, the
current sense amplifiers can not be
directly connected to the resistive
components. Unity gain low input offset
op-amps, U17, U19, U21 and U23,are
used in both the high and low side sense
lines. Voltage supplied to these parts
must be above the high voltage supply
rail and the V- pin must be less than the
high voltage supply but not as far down
as ground. Digital potentiometers, U38
and U39, are connected to each of the
high current monitoring circuits to allow
for calibration of the measured current
prior to the over current detection
circuits.
The PS +10VDC output is also used to
drive the gate of two external power
FETs. These FETs are located within the
amplifier module and are used to control
the high power supply current to the
amplifier pallets. Since the high power
supply voltage can be +48 Volts and the
2N7002LT1 is rated for a maximum
Drain to Source voltage of 60 Volts, Q9
along with Q8 make a circuit that
controls the high power supply control
voltage of the two external power FETs.
Q13 allows the hardware to
automatically disable the external power
FETs on detection of a critical fault. Q19
quickly reduces the drive level when a
fault is detected.
U50 detects the high power supply
voltage and generates a high power
supply voltage, high fault if it is too
high. U51 detects the high power
supply voltage and generates a high
power supply voltage, low fault if it is
too low. U58 is a digital potentiometer
that sets the over voltage to U50 and
under voltage to U51 fault thresholds.
U37 latches the fault so that the U2
microcontroller can observe the fault
condition even after the cause of the
fault is removed.
Volume 2, Rev. 0
3.2.2.8.4: Schematic Page 4:
The upper left corner contains U33 and
U34, which are analog multiplexer ICs
that are used to route selected analog
signals into the U2 microcontroller.
U32B converts the detected forward
power sample level into a module AGC
output voltage. CR51 allows the
module's AGC output voltage to be
connected to other module trays AGC
voltages. If this module tray has the
highest detected forward power in a
multi-amplifier system, it will have the
highest forward power signal and this
signal level into U32B pin 5 will be used
to set the AGC output voltage of the
3-11
Innovator HXB Series Digital
UHF Transmitter
Chapter 3, UHF Amplifier Tray and
Cabinet Assemblies Circuit Descriptions
system. If another amplifier has a
higher forward power, the level into
U32B pin 6 will be higher than pin 5 and
this amplifiers output signal will not be
used to set the AGC voltage level.
to +5Vdigital regulator. 100 mA of
current is available from each of the
devices.
3.3: Troubleshooting and Repair of
the Amplifier
High speed comparators U52, U53, U54,
and U55 monitor the current of the RF
final amplifier pallets. If any level is
greater than the fault level set by the
digital potentiometer U43, the fault is
detected and held by U41.
3.3.1: Safety Information
Work on the amplifier must only be
carried out by qualified personnel
according to good electrical engineering
practice, taking into account all relevant
safety precautions. Furthermore, the
following should be noted:
U44 is a digital potentiometer that sets
the AGC voltage level, the over drive
fault threshold and the module forward
power level.
•
3.2.2.8.5: Schematic Page 5:
The trays reflected power is monitored
through a RF detection circuit located on
Page 5 of the schematic. If the reflected
power level is greater than the fault
threshold level set by U43 pin 10,
located on Page 4 of the schematic,
which connects to U56 pin 1, U56 will
indicate a reflected power fault output at
pin 5. The fault is latched for detection
by the U2 microcontroller and also
biases On the switching diode CR66,
located on Page 2. This turns On the
FET Q13, which biases On Q8. +10VDC,
the High Power FET Gate Control, is
connected through Q8 to the main
control FET, located on the FET switch
metering board. The control FET is
biased Off and immediately removes the
supply voltages to the output amplifier
pallets.
In the lower left corner of the page are
voltage regulator circuits. U29 is a +12
VDC to +7V regulator that is rated for
0.14 amps of power using its 92° C/W
rating if Ta = 60°C max and Tj = 125°C
max. 0.26 amps can be obtained from
U29 if the thermal mounting pad is 0.5
square inches. The U2 controller does
not typically need this much current.
U30 and U31 are low drop-out voltage
regulators with a tolerance greater than
or equal to 1%. U30 is the +7V to
+5Vanalog regulator and U31 is the +7V
Volume 2, Rev. 0
3-12
Before working on an amplifier, e.g.,
removing cables, removing the front
panel etc., ensure that the amplifier
is disconnected from the operating
voltages. Carry out all work with
extreme caution.
3.3.2: Troubleshooting
3.3.2.1: Front Panel LEDs
A visual indication of the operating
status of the UHF amplifiers is signaled
by two front panel LEDs. Fault free
operation is signaled by the lit Green
Module OK LED, located nearest the
handle. A fault condition is indicated by
a Module OK, either continuously
illuminated Red or flashing Red.
The flashing Red Module OK LED
interprets as follows:
Table 3-4: DS4 Module OK LED Red and
Blinking interpretation
Red
LED
Blinking
1 Blink
2 Blinks
3 Blinks
4 Blinks
5 Blinks
6 Blinks
7 Blinks
Meaning
Indicates Amplifier Current Fault
Indicate Temperature Fault
Indicate Power Supply Over Voltage Fault
Indicate Power Supply Under Voltage Fault
Indicate Reflected Power Fault
Indicate +12V or –12V Power Supply Fault
Indicate AGC Overdrive
The other LED, on the front panel, is the
Enable LED, located nearest the edge. It
is Green when an Enable is applied to
Innovator HXB Series Digital
UHF Transmitter
Chapter 3, UHF Amplifier Tray and
Cabinet Assemblies Circuit Descriptions
that amplifier and it is operating. It will
not be lit if the Enable is removed. It
will be lit Amber if the Enable is applied
but the amplifier is not operating.
and output connections of the defective
module.
NOTE: The temperature sensors A15 or
A16 may need to be unscrewed to
remove the module.
3.3.2.2: Polling Fault Indications
Detected fault conditions are passed to
the system control unit. The fault
indications are entered in a list and can
be viewed at any time during
transmitter operation.
After undoing the screws, the module
can be lifted from the heat sink.
Remove the old heat-transfer paste from
the heat sink.
The system control unit is used for
polling stored fault indications and
reading actual operating parameters.
NOTE: In order to ensure proper heat
conduction, the contact surface of the
heat sink must be clean and free of
foreign particles.
3.4: Exchanging Amplifiers
3.4.2: Mounting a New Module
For reasons of safety, amplifier tray
assemblies MUST be in standby (RF
disabled) before any connections are
removed. An Axcera Amplifier disable
plug (1308219) can be used to place an
individual tray in standby. Regardless of
the version of the code, any power
amplifier may safely be removed by
disabling its power supply. The power
supply, either the top power supply #1
for the top four Amplifier assemblies, or
the bottom power supply #2 for the
bottom four Amplifier assemblies, may
be isolated from the main AC power by
switching off the associated circuit
breaker located on the circuit breaker
assembly panel, at the bottom of the
amplifier cabinet.
Apply a thin film of heat-transfer paste
to the contact surface.
3.4.1: Exchange of a Module within a
Tray Assembly
Caution: The load (balancing)
resistors in the modules contain
Beryllium Oxide.
Remove the amplifier from the cabinet
as described in the Chapter 2 section 2.7
of this volume of the instruction manual.
Undo the covers panel of the amplifier
tray.
Unsolder the connections for the
operating voltage as well as the RF input
Volume 2, Rev. 0
3-13
Fix the module into position with the
mounting screws. At first, only tighten
the screws by hand.
Next, tighten the screws, in repeated
steps, to a torque of 0.8 Nm (7 in/lb).
Caution: A torque of 1.2 Nm
(10 in/lb) must not be exceeded.
(1.2 NM ≈ 10 in/lb)
(0.8 Nm ≈ 7 in/lb)
3.4.3: Final Steps
Replace the cover on the amplifier,
insert the tray assembly into the
transmitter cabinet, and make the RF
input and output connections as
described in Chapter 2 section 2.7 of this
volume of the instruction manual.
NOTE: Alignment work on the amplifier
is not required. They are set at the
factory for both phase and gain control
and provide less than 0.5 dB difference
between the amplifiers. The exchange
of a module should be reported to
Axcera with information on the cause of
the fault, module location, identification
number of the amplifier, and the type of
transmitter.
Innovator HXB Series Digital
UHF Transmitter
Chapter 3, UHF Amplifier Tray and
Cabinet Assemblies Circuit Descriptions
3.4.4: External Connections to Amplifier Assembly
Table 3-5: RF Connectors on the Front Panel
Connector
Assignment
Type
J1
RF Input
Female N-type
J2
RF Output
Female HF 7/16”
J3
RF Test Point
Female N-type
RS 232 C
reserved for factory alignment only!
Table 3-6: Operating Voltage Connection (Rear Panel)
Pin
Assignment
J5
+48 V
J6
Ground
3.5: Power Supply Assembly
Figure 3-6: AC Wiring Harness UHF Amplifier Cabinet
Volume 2, Rev. 0
3-14
Innovator HXB Series Digital
UHF Transmitter
Chapter 3, UHF Amplifier Tray and
Cabinet Assemblies Circuit Descriptions
3.5.1: +48 VDC Power Supplies
Overview
breaker controls the voltage to power
supply #2.
The DC voltages to the UHF amplifier
tray assemblies mounted in each UHF
amplifier cabinet are supplied by either
one or two linear power supply
assemblies. One supply, titled the top
power supply #1, provides +48 VDC to
the four UHF amplifier tray assemblies
mounted at the top of the cabinet for 5
kW amplifier cabinets or three UHF
amplifier assemblies mounted at the top
of the cabinet for 3.7 kW amplifier
cabinets. The other supply, titled the
bottom power supply #2, provides +48
VDC to the four UHF amplifier tray
assemblies mounted at the bottom of
the cabinet for 2.5 & 5 kW amplifier
cabinets or to three UHF amplifier tray
assemblies mounted at the bottom of
the cabinet for 1.8 or 3.7 kW amplifier
cabinets.
The two +48 VDC power supplies, (A8)
#1 and (A9) #2, are identical with each
containing a SCR Controller, a
transformer and a linear power supply.
3.5.2: SCR Controllers
The two SCR controllers, (A4) SCR
Controller #1 and (A5) SCR Controller
#2 are manufactured by Control
Concepts, Inc. The SCR controller is of a
phase angle, pulse width, control design.
The output power is regulated by
varying the point at which the SCR is
turned on within each half cycle. NOTE:
More detailed information is supplied in
the manufacturer instruction manual
that is supplied with the SCR Controller.
3.5.3: Step Down Transformers
Refer to Figure 3-6 while reading the
following description. Two input AC
connections of 480 VAC, 3 phase or 208
VAC 3 phase and one 110 VAC input
connection are needed to operate each
UHF Amplifier Cabinet. The 110 VAC
input connects to the (A1-A2) Terminal
Block #3 mounted at the top left side, at
the rear of the cabinet. The 110 VAC is
wired directly to a terminal block TB1
located in the AC power distribution
panel mounted at the bottom of the
cabinet. One of the 480/208 VAC, 3
phase inputs connects to the (A1-A1)
Terminal Block #1 and the other to the
(A2) Terminal Block #2 mounted top left
side, at the rear of the cabinet. The two
480/208 VAC inputs are wired directly to
the circuit breakers (A1-A1) Terminal
Block #1 to CB1 and (A2) Terminal
Block #2 to CB2 located in the AC power
distribution panel mounted at the
bottom of the cabinet. The AC input
voltages to the two power supplies are
controlled through the two 480 VAC 30
Amp or 208 VAC 50 Amp 3 Phase circuit
breakers located on the (A3) AC power
distribution panel. The left front circuit
breaker controls the voltage to power
supply #1 and the right front circuit
Volume 2, Rev. 0
3-15
The outputs of the two SCR controllers
connect to one of the two three phase
480/208 VAC step down transformers.
The (A6) Transformer #1 or (A7)
Transformer #2, whose input
connections are set at the factory
depending on the input voltage provided
and supplies three outputs that connect
directly to the input of the linear power
supply assemblies.
3.5.4: +48 VDC Linear Power Supply
Assemblies (1307172 Top or
1307173 Bottom; Appendix C)
(Refer to Figures 3-7 & 3-8) Both of the
Power Supply Assemblies, Top #1 and
Bottom #2, are identical in operation,
the only differences are in the physical
assembly itself. The three stepped down
outputs of the transformer,
approximately 100 VAC, connect to one
of the three Rectifier Modules (A1-A3).
The rectifier modules are full wave
rectifiers that each produce
+46.5 VDC, which are summed in
parallel at the Bus Bars B and 3. The
+46.5 VDC outputs are filtered by the
eight A4-A11 100,000µF capacitors.
Capacitors A4-A7 through Bus Bar C are
Innovator HXB Series Digital
UHF Transmitter
Chapter 3, UHF Amplifier Tray and
Cabinet Assemblies Circuit Descriptions
for Amps #1 and #2, with the top power
supply, or Amps #5 and #6, with the
bottom power supply. Capacitors A8A11 through Bus Bar E are for Amps #3
and 4, with the top power supply or
Amps #7 and #8, with the bottom
power supply.
The board samples the 3 phase AC input
lines at J1, J2 and J3. Each AC leg is full
wave rectified by diodes CR1-CR6 and
filtered by C1. This DC voltage counted
to the SCR controller assembly which
causes more or less turn on time for the
cycles, that increases or decreases the
AC input to the power supply affected
which increases or decreases the DC
voltage output of the power supply.
3.5.4.1: Power Supply Monitoring
Board (1307059; Appendix C)
Each amplifier assembly has (A12) a
power supply monitoring board, which
contains the range adjustment using R6
and the feedback adjustment using R8
potentiometers for the power supply in
which the board is contained. These
adjustments control the SCR Controller
Volume 2, Rev. 0
Assembly which in turn controls the
output voltage level of the power supply.
NOTE: The settings of these two pots
were completed at the factory and
should not be adjusted because damage
may occur to the amplifier devices.
3-16
Volume 2, Rev. 0
Innovator HXB Series Digital
UHF Transmitter
3-17
Figure 3-7: +48 VDC Linear Power Supply #1, Top
Chapter 3, UHF Amplifier Tray and
Cabinet Assemblies Circuit Descriptions
Volume 2, Rev. 0
Innovator HXB Series Digital
UHF Transmitter
3-18
Figure 3-8:+48 VDC Linear Power Supply #2, Bottom
Chapter 3, UHF Amplifier Tray and
Cabinet Assemblies Circuit Descriptions
Volume 2, Rev. 0
Innovator HXB Series Digital
UHF Transmitter
3-19
Figure 3-9: Full Cabinet Controller System Interconnect
Chapter 3, UHF Amplifier Tray and
Cabinet Assemblies Circuit Descriptions
Innovator HXB Series Digital
UHF Transmitter
Chapter 3, UHF Amplifier Tray and
Cabinet Assemblies Circuit Descriptions
3.6: Full Amplifier Cabinet Controller
Board (1307523; Appendix A)
Your amplifier cabinet will contain the
full amplifier cabinet controller assembly
or the half amplifier cabinet controller
assembly. The half amplifier cabinet
controller assembly is described in the
next section.
The full amplifier cabinet controller
board is mounted in the Full Amplifier
Cabinet Controller Assembly (1305453).
The assembly is located facing the back
of the cabinet mounted on the rear of
the top combiner assembly and controls
the entire amplifier cabinet.
3.6.1: Schematic Drawing 1307524
Page 1:
Centered in page one of the schematic s
the microcontroller (U6). This in-circuit
programmable Atmel microcontroller is
operated at 3.6864 MHz. Programming
of this device is performed through
J105. PF2 is an analog input that
connects to a multiplexer U9 and PF3 is
another analog input that connects to
the multiplexer U5. The desired
multiplexer analog channels are selected
by the setting of PA0, PA1, & PA2. PF0
and PF1 are used to monitor the +12V
and -12V supplies to the board.
(U12) is a watchdog IC that is used to
hold the microcontroller in reset if the
supply voltage is less than 4.21 VDC;
(1.25 VDC < Pin 4 (IN) < Pin 2 (Vcc)).
U12 will momentarily reset the
microcontroller if Pin 6 is not clocked
every second.
The (U6) Microcontroller UART 0 is used
to communicate with each of the
amplifier modules, Cabinet Serial. U10
is a RS-485 transceiver IC for cabinet
serial communication to the amplifier
modules. The (U6) Microcontroller UART
1 is used to communicate with the
transmitter's exciter or exciter switcher,
System Serial. U8 is a RS-485
transceiver IC.
Volume 2, Rev. 0
3-20
The IC U2, Serial Address, located in the
Upper left corner, is used to determine
where the amplifier control board is
located. Rotary switch SW1 determines
the cabinet number and thus the
cabinet's serial address. The upper
three bits of U2 can be used to
determine physical board characteristics.
Bit 6 will be reserved for a half cabinet
controller to determine if the controller
is the top half controller or the bottom
half controller.
The IC U3, SCR Controllers, below U2, is
used to monitor the status of the SCR
controllers. U7 below U3 is connected to
an 8 position DIP switch, SW2, which
can be used to enable select firmware
options. See Table 3-7. U11, below U7,
is used to control the SRC controller, the
cabinet's cooling blower FET, and the
Processor Operating LED, DS2. The use
of this IC allows these circuits to remain
stable during a microcontroller reset.
3.6.2: Schematic Page 2:
In the upper left section of Page 2 are
circuits that interface with the exhaust
air temperature board and the low
power +15VDC switching supply.
Control of an external cooling blower
relay is available through J125 pin 20.
When the cabinet's RF output is enabled,
the external blower relay is energized by
the enabling of Q3 on page 1. Voltage
samples of the cabinet's high power AC
inputs are monitored through inputs of
J125.
On the upper right side of the schematic,
the Power Supply SCR Controller
interface section routes signals need to
control the high power supply. R120,
R121, R122, and R123 are used to set
the output voltage of the high power
supply.
Amplifier module interfaces are routed
through J101, for modules 1-4, and
J102, for modules 5-8. Each amplifier
module has independent RS-485
transceivers and power sources that are
current limited with self-resetting fuses.
Innovator HXB Series Digital
UHF Transmitter
Chapter 3, UHF Amplifier Tray and
Cabinet Assemblies Circuit Descriptions
The RS485 interface section, located in
the lower right section of the schematic,
defines the RS-485 loop through
connections that also contain the
system's AGC signals. Circuitry in the
lower portion of this block is used to
convert cabinet AGC voltages into
system AGC voltages. If the cabinet
level voltages are greater than the
system levels, U13 increases its output
to drive the system level to match the
cabinet level. Cabinet AGC levels are
set by the highest AGC voltage of the
install amplifier modules.
3.6.4: Schematic Page 4:
These circuits take the forward and
reflected RF power samples and converts
the signals to DC values used to provide
power levels for the cabinet monitoring.
The RF detection circuits are made up of
diodes and separate op-amps. Once the
detected voltages are amplified, the
signals are fed through power calibration
potentiometers, R110, R11, R112, R113
or R114, before they are fed through
unity gain amplifiers, U20, U23A, U23B,
U24A or U24B to the microcontroller's
multiplexer.
3.6.3: Schematic Page 3:
3.6.5: Schematic Page 5:
In the upper left portion of the
schematic, R125 is used to measure the
cabinet's inlet air temperature. Also
defined on this page are the board's
voltage regulators. The cabinet's +15V
supply is used by U14 and U17 to
generate +12V for all of the amplifier
modules. The cabinet's -15V supply is
used by U19 to generate -12V for all of
the amplifier modules. The +12V signal
is further regulated by U16 to +7 VDC
then regulated again to separate digital
+5V by U18 and analog +5V by U15.
The digital +5V regulator U18 is not as
precise as the analog +5V regulator U15
but it is capable of high current loads.
These eight circuits are individual RS485 transceiver ICs for serial
communication with the amplifier
modules. The RS-485 transceiver ICs
contain components that maintain the
receive channel in a high output state
when the inputs are left open, shorted
together or terminated with no signal.
The transmit and receive channels of
each transceiver are individually
controlled by the microcontroller.
During reset or programming of the
microcontroller, pull-up and pull-down
resistors are used to place the
transceivers in a tri-state condition.
Each amplifier RS-485 connection is
terminated with a 120 Ω resistor.
Table 3-7: Firmware Configuration of SW2 on Full Amplifier Cabinet Controller Board
Switch
Number
Function
SW2-1
Reserved for Factory Test
SW2-2
SW2-3
Position
Allow Power Supply Enable on Cooling
FLT
Allow Power Supply Enable on RFL PWR
FLT
SW2-4
High Voltage Supply Range
SW2-5
Reflected Power RF Source
SW2-6
Allow Power Supply Enable on Reject
Load Faults
SW2-7
Reserved for Factory Test
SW2-8
Reserved for Factory Test
0 = Off
1 = On
0 = Off
1 = Allow
0 = Off
1 = Allow
0 = 220
1 = 440
0 = J112
1 = J114 (If not
Externally Diplexed)
0 = Off
1 = Allow
0 = Off
1 = On
0 = Off
1 = On
Normal
Operating
Position
Off - Must be
Off
Off - Must be
Off
Off
System
dependent
System
dependent
Off
Off - Must be
Off
Off - Must be
Off
NOTE: These switch positions are factory set and should not be changed.
Volume 2, Rev. 0
3-21
Innovator HXB Series Digital
UHF Transmitter
Chapter 3, UHF Amplifier Tray and
Cabinet Assemblies Circuit Descriptions
3.7: Half Amplifier Cabinet Controller
Board (1307840; Appendix A)
microcontroller if Pin 6 is not clocked
every second.
The half amplifier cabinet controller
board is mounted in the Half Amplifier
Cabinet Controller Assembly (1307847).
There are typically two assemblies,
which are mounted facing the rear of the
cabinet. One controller is mounted on
the rear of the top combiner assembly,
which controls the top power supply and
amplifier module assemblies and one
mounted on the rear of the bottom
combiner assembly which controls the
bottom power supply and amplifier
module assemblies.
The Microcontroller UART 0 is used to
communicate with each of the amplifier
modules, Cabinet Serial. U10 is a RS485 transceiver IC for cabinet serial
communication to the amplifier modules.
3.7.1: Schematic 1307841 Page 1:
Centered in page one is the
microcontroller (U6). This in-circuit
programmable Atmel microcontroller is
operated at 3.6864 MHz. Programming
of this device is performed through
J105. PF2 is an analog input that
connects to a multiplexer U9. PF3 is
another analog input that connects to
the multiplexer U5. The desired
multiplexer analog channels are selected
by the setting of PA0, PA1, & PA2. PF0
and PF1 are used to monitor the +12V
and -12V supplies to the board.
(U12) is a watchdog IC that is used to
hold the microcontroller in reset if the
supply voltage is less than 4.21 VDC;
(1.25 VDC < Pin 4 (IN) < Pin 2 (Vcc)).
U12 will momentarily reset the
Volume 2, Rev. 0
3-18
The Microcontroller UART 1 is used to
communicate with the transmitter's
exciter or exciter switcher, System
Serial. U8 is a RS-485 transceiver IC.
The IC U2, Serial Address, located in the
Upper left corner, is used to determine
where the amplifier control board is
located. Rotary switch SW1 determines
the cabinet number and thus the
cabinet's serial address. The upper
three bits of U2 can be used to
determine physical board characteristics.
The IC U3, SCR Controllers, is located
below U2. U3 is used to monitor the
status of the SCR controllers. U7 below
U3 is connected to an 8 position DIP
switch, SW2, which can be used to
enable select firmware options. See
Table 3-7.
U11, below U7, is used to control the
SRC controller, the cabinet's cooling
blower FET, and the Processor Operating
LED, DS2. The use of this IC allows
these circuits to remain stable during a
microcontroller reset.
Volume 2, Rev. 0
Innovator HXB Series Digital
UHF Transmitter
3-23
Figure 3-10: Half Cabinet Controller System Interconnect
Chapter 3, UHF Amplifier Tray and
Cabinet Assemblies Circuit Descriptions
Innovator HXB Series Digital
UHF Transmitter
Chapter 3, UHF Amplifier Tray and
Cabinet Assemblies Circuit Descriptions
3.7: Half Amplifier Cabinet Controller
Board (1307840; Appendix A)
The half amplifier cabinet controller
board is mounted in the Half Amplifier
Cabinet Controller Assembly (1307847).
There are typically two assemblies,
which are mounted facing the rear of the
cabinet. One controller is mounted on
the rear of the top combiner assembly,
which controls the top power supply and
amplifier module assemblies and one
mounted on the rear of the bottom
combiner assembly which controls the
bottom power supply and amplifier
module assemblies.
3.7.1: Schematic 1307841 Page 1:
Centered in page one is the
microcontroller (U6). This in-circuit
programmable Atmel microcontroller is
operated at 3.6864 MHz. Programming
of this device is performed through
J105. PF2 is an analog input that
connects to a multiplexer U9. PF3 is
another analog input that connects to
the multiplexer U5. The desired
multiplexer analog channels are selected
by the setting of PA0, PA1, & PA2. PF0
and PF1 are used to monitor the +12V
and -12V supplies to the board.
(U12) is a watchdog IC that is used to
hold the microcontroller in reset if the
supply voltage is less than 4.21 VDC;
(1.25 VDC < Pin 4 (IN) < Pin 2 (Vcc)).
U12 will momentarily reset the
microcontroller if Pin 6 is not clocked
every second.
The IC U3, SCR Controllers, is located
below U2. U3 is used to monitor the
status of the SCR controllers. U7 below
U3 is connected to an 8 position DIP
switch, SW2, which can be used to
enable select firmware options. See
Table 3-7.
U11, below U7, is used to control the
SRC controller, the cabinet's cooling
blower FET, and the Processor Operating
LED, DS2. The use of this IC allows
these circuits to remain stable during a
microcontroller reset.
3.7.2: Schematic Page 2:
In the upper left section of Page 2 are
circuits that interface with the exhaust
air temperature board and the low
power +15VDC switching supply.
Control of an external cooling blower
relay is available through J125 pin 20.
When the cabinet's RF output is enabled,
the external blower relay is energized by
the enabling of Q3 on page 1.
Voltage samples of the cabinet's high
power AC inputs are also monitored
through inputs of J125.
The Microcontroller UART 0 is used to
communicate with each of the amplifier
modules, Cabinet Serial. U10 is a RS485 transceiver IC for cabinet serial
communication to the amplifier modules.
The Microcontroller UART 1 is used to
communicate with the transmitter's
exciter or exciter switcher, System
Serial. U8 is a RS-485 transceiver IC.
The IC U2, Serial Address, located in the
Upper left corner, is used to determine
where the amplifier control board is
Volume 2, Rev. 0
located. Rotary switch SW1 determines
the cabinet number and thus the
cabinet's serial address. The upper
three bits of U2 can be used to
determine physical board characteristics.
3-24
Power Supply SCR Controller interfaces
are documented in the upper right side
of the schematic. This section routes
signals need to control and monitor one
of the high power supply SCR
controllers. Supply voltage and reject
load monitoring signals are also routed
through J120.
The four amplifier module interfaces are
routed through J101. Each amplifier
module has independent RS-485
transceivers and power sources, that are
current limited with self-resetting fuses.
The RS485 interface section, located in
the lower right section of the schematic,
Innovator HXB Series Digital
UHF Transmitter
Chapter 3, UHF Amplifier Tray and
Cabinet Assemblies Circuit Descriptions
defines the RS-485 loop through
connections and contains the system's
AGC signals. Circuitry in the lower
portion of this block is used to convert
cabinet AGC voltages into system AGC
voltages. If the cabinet level voltages
are greater than the system levels, U13
increases its output to drive the system
level to match the cabinet level. Cabinet
AGC levels are set by the highest AGC
voltage of the installed amplifier
modules.
3.7.3: Schematic Page 3:
In the upper left portion of the
schematic, R125 is used to measure the
cabinet's inlet air temperature. Also
defined on this page are the board's
voltage regulators. The cabinet's +15V
supply is used by U14 to generate +12V
for all of the amplifier modules. The
cabinet's -15V supply is used by U19 to
generate -12V for all of the amplifier
modules. The +12V signal is further
regulated by U16 to +7 VDC then
regulated again to separate digital +5V
by U18 and analog +5V by U15. The
digital +5V regulator U18 is not as
precise as the analog +5V regulator U15
but it is capable of high current loads.
3.7.4: Schematic Page 4:
These circuits take the forward and
reflected RF power samples and converts
the signals to DC values used to provide
power levels for the cabinet monitoring.
The RF detection circuits are made up of
diodes and separate op-amps. Once the
detected voltages are amplified, the
signals are fed through power calibration
potentiometers, R110, R11, R112, R113
or R114, before they are fed through
unity gain amplifiers, U20, U23A, U23B,
U24A or U24B to the microcontroller's
multiplexer.
3.7.5: Schematic Page 5:
These four circuits are individual RS-485
transceiver Ics for serial communication
with the amplifier modules. The RS-485
transceiver ICs contain components that
maintain the receive channel in a high
output state when the inputs are left
open, shorted together or terminated
with no signal. The transmit and receive
channels of each transceiver are
individually controlled by the
microcontroller. During reset or
programming of the microcontroller,
pull-up and pull-down resistors are used
to place the transceivers in a tri-state
condition. Each amplifier RS-485
connection is terminated with a 120Ω
resistor.
Table 3-8: Firmware Configuration of SW2 on Half Amplifier Cabinet Controller Board
Normal
Switch
Function
Position
Operating
Number
Position
0 = Off
Off - Must
SW2-1
Reserved for Factory Test
1 = On
be Off
Allow Power Supply Enable on
0 = Off
Off - Must
SW2-2
Cooling FLT
1 = Allow
be Off
Allow Power Supply Enable on
0 = Off
SW2-3
Off
RFL PWR FLT
1 = Allow
0 = 220
System
SW2-4
High Voltage Supply Range
1 = 440
dependent
0 = J112
SW2-5
Reflected Power RF Source
1 = J114 (If not
System
Externally Diplexed) dependent
Allow Power Supply Enable on
0 = Off
SW2-6
Off
Reject Load Faults
1 = Allow
Volume 2, Rev. 0
3-25
Innovator HXB Series Digital
UHF Transmitter
Chapter 3, UHF Amplifier Tray and
Cabinet Assemblies Circuit Descriptions
0 = Off
Off - Must
1 = On
be Off
0 = Off
Off - Must
SW2-8
Reserved for Factory Test
1 = On
be Off
NOTE: These switch positions are factory set and should not be changed.
SW2-7
Reserved for Factory Test
3.8: Temperature Sensor Board
(1309460; Appendix A)
power supply DC voltage rises above a
given threshold level. The threshold
level is factory pre-set on the Load
Regulator Board.
The temperature sensor board is
mounted at the top of the amplifier
cabinet in the airflow path inside the
exhaust plenum. The board monitors
the temperature of the exhausted air
and reports it to the cabinet controller
board.
3.10.1: Load Regulator Board, +48
VDC (1308393; Appendix A)
The load regulator board is mounted in
the load regulator assembly (1308386).
3.9: Serial Loop-Thru Board
(1307811; Appendix A)
The serial loop-thru board is mounted on
the metering module assembly located
on the rear middle, left side of the
amplifier cabinet.
The function of the serial loop-thru board
is to provide an extra serial loop-thru that
connects to the second amplifier cabinet.
This prevents the system controller from
not recognizing any amplifier cabinets if
one system controller is removed.
NOTE: In a multiple amplifier cabinet
system, there will not be a serial loopthru board in the last amplifier cabinet in
the system.
3.10: Load Regulator Assembly, +48
VDC (1308386; Appendix A)
The load regulator assembly contains a
load regulator board, +48 VDC
(1308393). The Load Regulator
Assembly is designed to temporarily
activate and maintain a constant load on
the output of the power supply
assembly, which due to load changes,
can cause the DC output from the
affected power supply to rise.
The Load Regulator Assembly monitors
the DC output from the power supply
and adds additional load resistance if the
Volume 2, Rev. 0
3-26
There are two identical regulator circuits
on the board. The top power supply
circuit contains Q3 and the bottom
power supply circuit contains Q6. Just
the top power supply circuit will be
described as follows.
The Load Regulator Board receives a
sample of the DC voltage from the top
power supply at J1. The top power
supply voltage is then regulated down to
a lower voltage by varistors, VR1-VR5
and powers a +12V regulator, U1 which
supplies the +12VDC (+12V1) to the
rest of the circuits in the top power
supply control. The Trip threshold is set
by R16 to +50.0 VDC for the +46.5V
power supply. If the power supply
voltage exceeds the above set level, the
FET switch Q3 is biased on and provides
a contact closure. This contact closure
adds additional 1Ω/300W load
resistances, R1-R3, across the DC output
of the affected power supply. Once the
DC voltage returns to normal, the FET
switch is biased off and the switch
opens, thereby removing the additional
load resistance.
There are thermal switches mounted on
the FETs and the power resistors that
will open shut down the associated
power supply should an over
temperature fault occur, >70°C.
Thermal Switch S1 is mounted on Q3,
for the top power supply, S2 is mounted
Innovator HXB Series Digital
UHF Transmitter
Chapter 3, UHF Amplifier Tray and
Cabinet Assemblies Circuit Descriptions
on Q6, for the bottom power supply, S3
is mounted on R1, for the top power
supply and S4 is mounted on R4, for the
bottom power supply.
Volume 2, Rev. 0
This completes the description of the
UHF Amplifier Tray Assembly and other
Cabinet Assemblies.
3-27
Innovator HXB Series Digital
UHF Transmitter
Appendix A, RF Amplifier Assembly
Drawings and Parts Lists
Appendix A
RF Amplifier Cabinet Assembly,
HXB Series
Drawings
Volume 2, Rev. 0
A-1
Innovator HXB Series Digital
UHF Transmitter
Appendix A, RF Amplifier Assembly
Drawings and Parts Lists
Appendix A
Drawing List
UHF Amplifier Cabinet, HXB Series, UHF, 480V, Two Power Supplies
(Maximum of 5 kW Digital Output)
UHF Amplifier Cabinet, 8 Way Combiner Block Diagram ................................ 1306714
RF Signal, 8 Way, Full Controller, Interconnect ............................................ 1306574
RF Cabinet, Full Controller Interconnect ...................................................... 1306573
RF Cabinet, HXB, 480VAC Interconnect ....................................................... 1312292
Full Amplifier Cabinet Controller Board, HXB Series (Mounted in the Full Amplifier
Cabinet Controller Assembly, HXB Series, 1305453)
Schematic................................................................................................ 1307524
Serial Loop-Thru Board
Schematic................................................................................................ 1307812
Load Regulator Assembly, +48 VDC
(Contains a Load Regulator Board +48 VDC, 1308393)
Interconnect............................................................................................. 1308499
Load Regulator Board, +48 VDC
(Mounted in a Load Regulator Assembly, +48 VDC, 1308386)
Schematic................................................................................................ 1308394
Quadrature Splitter Board (Mounted in a Quadrature Splitter Module Assembly, 1309334
Schematic................................................................................................ 1309324
Temperature Sensor Board, HXB Series
Schematic................................................................................................ 1309461
AC Line Monitoring Board, HXB Series, 480V (Used in Power Distribution Panel, 1312441)
Schematic................................................................................................ 1311425
Power Distribution Panel, UHF Amplifier Cabinet, HXB Series, 480V
(Contains an AC Line Monitoring Board, 1312424)
Interconnect............................................................................................. 1312464
8 Way UHF Combiner (Contains two 4 Way UHF Combiners, 1300129)
Interconnect............................................................................................. 1181730
Volume 2, Rev. 0
A-2
Innovator HXB Series Digital
UHF Transmitter
Appendix B, UHF Amplifier Tray Assembly
Drawings and Parts Lists
Appendix B
UHF Amplifier Tray Assembly, Broadband, HXB Series
Drawings
Volume 2, Rev. 0
B-1
Innovator HXB Series Digital
UHF Transmitter
Appendix B, UHF Amplifier Tray Assembly
Drawings and Parts Lists
Appendix B
Drawing List
UHF Amplifier Tray Assembly, HXB Series (Maximum of Eight used in each
Amplifier Cabinet)
UHF Amplifier Tray Assembly Block Diagram................................................ 1311957
UHF Amplifier Tray Assembly Interconnect .................................................. 1311947
4 Way Splitter Assembly, UHF
Schematic.......................................................................................... 1306372
Dual BLF871 Amplifier Board, HXB (Mounted in a Dual BLF871 Amp Assy., 1311991)
Schematic.......................................................................................... 1311579
Phase/Gain Board, HXB (Mounted in a Phase/Gain Assembly, 1311993)
Schematic.......................................................................................... 1311584
Amplifier Control Board, HX Series
Schematic.......................................................................................... 1311684
Output Coupler Board, UHF, HXB
Schematic .......................................................................................... 1311883
FET Switch/Metering Board, UHF, HXB Series
Schematic.......................................................................................... 1312343
878 Amplifier Pallet Assembly, Analog Bias (Four used in each UHF Amplifier Assembly)
Schematic.......................................................................................... 1313171
Volume 2, Rev. 0
B-2
Innovator HXB Series Digital
UHF Transmitter
Appendix C, Power Supply Assemblies,
Top & Bottom Drawings and Parts Lists
Appendix C
Power Supply Assemblies, Top and Bottom,
HXB Series, +48V
Drawings
Volume 2, Rev. 0
C-1
Innovator HXB Series Digital
UHF Transmitter
Appendix C, Power Supply Assemblies,
Top & Bottom Drawings and Parts Lists
Appendix C
Drawing List
Power Supply Assembly, Top, HXB Series, +48V O/P
Interconnect ...................................................................................... 1307189
Power Supply Assembly, Bottom, HXB Series, +48V O/P
Interconnect ...................................................................................... 1307190
Power Supply Monitoring Board, HXB Series (One mounted in each Power Supply
Assembly)
Schematic.......................................................................................... 1307060
Volume 2, Rev. 0
C-2

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