Broadcast Electronics AM-2.5E User manual

WARNING
OPERATING HAZARDS
READ THIS SHEET AND OBSERVE ALL SAFETY PRECAUTIONS
ALL PERSONS WHO WORK WITH OR ARE EXPOSED TO POWER TRANSISTORS MUST TAKE PRECAUTIONS
TO PROTECT THEMSELVES AGAINST POSSIBLE SERIOUS BODILY INJURY. EXERCISE EXTREME CARE
AROUND SUCH PRODUCTS. UNINFORMED OR CARELESS OPERATION OF THESE DEVICES CAN RESULT
IN POOR PERFORMANCE, DAMAGE TO THE DEVICE OR PROPERTY, SERIOUS BODILY INJURY, AND POSSI-
BLY DEATH.
DANGEROUS HAZARDS EXIST IN THE OPERATION OF POWER TRANSISTORS
The operation of power tubes and power transistors involves one or more of the following hazards, any one of which,
in the absence of safe operating practices and precautions, could result in serious harm to personnel.
A. HIGH VOLTAGE – Normal operating voltages can be deadly. Additional information follows.
B. RF RADIATION – Exposure to RF radiation may cause serious bodily injury possibly resulting in
blindness or death. Cardiac pacemakers may be affected. Additional information follows.
C. BERYLLIUM – OXIDE POISONING – Dust or fumes from BeO ceramics used as thermal links with
power transistors are highly toxic and can cause serious injury or death. Additional information follows.
D. HOT SURFACES – Surfaces of air–cooled heat sinks radiators can reach temperatures of 100 degrees
centigrade and cause burns if touched. Additional information follows.
E. RF BURNS – Circuit boards with RF power transistors contain high RF potentials. Do not operate an RF
power module with the cover removed.
HIGH VOLTAGE
The transmitter operates at voltages high enough to kill through electrocution. Personnel should always break the
primary circuits when access to the transmitter is required.
RADIO FREQUENCY RADIATION
Exposure of personnel to RF radiation should be minimized, personnel should not be permitted in the vicinity of open
energized RF generating circuits, or RF transmission systems (waveguides, cables, connectors, etc.), or energized
antennas. It is generally accepted that exposure to “high levels” of radiation can result in severe bodily injury includ-
ing blindness. Cardiac pacemakers may be affected.
The effect of prolonged exposure to “low level” RF radiation continues to be a subject of investigation and controver-
sy. It is generally agreed that prolonged exposure of personnel to RF radiation should be limited to an absolute mini-
mum. It is also generally agreed that exposure should be reduced in working areas where personnel heat load is
above normal. A 10 mW/cm2per one tenth hour average level has been adopted by several U.S. Government agen-
cies including the Occupational Safety and Health Administration (OSHA) as the standard protection guide for em-
ployee work environments. An even stricter standard is recommended by the American National Standards Institute
which recommends a 1.0 mW/cm2per one tenth hour average level exposure between 30 Hz and 300 MHz as the
standard employee protection guide (ANSI C95.1–1982).
RF energy must be contained properly by shielding and transmission lines. All input and output RF connections, such
as cables, flanges and gaskets must be RF leakproof. Never operate a power tube without a properly matched RF
energy absorbing load attached. Never look into or expose any part of the body to an antenna, open RF generating
circuit, or RF transmission system while energized. Monitor the tube and RF system for RF radiation leakage at regu-
lar intervals and after servicing.
DANGER –– BERYLLIUM OXIDE CERAMICS (BeO) – AVOID BREATHING DUST OR FUMES
BeO ceramic material is used as a thermal link to carry heat from a transistor to the heat sink. Do not perform any
operation on any BeO ceramic which might produce dust or fumes, such as grinding, grit blasting, or acid cleaning.
Beryllium oxide dust or fumes are highly toxic and breathing them can result in serious personal injury or death. BeO
ceramics must be disposed of only in a manner prescribed by the device manufacturer.
HOT SURFACES
Heat sinks and reject loads are air–cooled or conduction–cooled. The air–cooled external surface can operate at a
high temperature (up to 100°C). All hot surfaces may remain hot for an extended time after the transmitter is oper-
ated to off. To prevent serious burns, take care to prevent and avoid any bodily contact with these surfaces both dur-
ing and for a reasonable cooling down period after operation.

TRANSMITTER WARRANTY VOID NOTICE
THE PRODUCT WARRANTY WILL BE VOID IF THE
TRANSMITTER IS INSTALLED AT A SITE WITH
INADEQUATE LIGHTNING PROTECTION AND A
DEFECTIVE TRANSMISSION LINE SYSTEM.
The transmitter is covered by a two year limited product warranty from Broadcast Elec
tronics. However, the transmitter must be properly installed at a site with adequate
lightning protection and transmission line systems. TO ENSURE THE TRANSMIT
TER WARRANTY IS VALID, the transmitter must be installed: 1) as described by the
INSTALLATION procedures presented in SECTION II of this manual, 2) at a transmitter
site with a lightning protection system described in TRANSMITTER SITE LIGHTNING
PROTECTION SYSTEM CHECKOUT (refer to SECTION II of this manual), and 3) at a
transmitter site with a transmission line system described in TRANSMISSION LINE
AND ANTENNA CHECKOUT (refer to SECTION II of this manual). FAILURE TO
PROPERLY INSTALL THE TRANSMITTER, PROVIDE AN ADEQUATE LIGHT
NING PROTECTION SYSTEM, OR PROVIDE AN ADEQUATE TRANSMISSION
LINE SYSTEM WILL VOID THE WARRANTY ON THE TRANSMITTER. If any
questions develop concerning the transmitter warranty and installation site systems, con
tact the Broadcast Electronics Customer Service Department.
BROADCAST ELECTRONICS, INC.

NOTICE TO THE EQUIPMENT USER
FCC Rule 73.1590 mandates the licensee of each AM station to make measurements for
spurious and harmonic emissions to show compliance with the transmission system re
quirements of Section 73.44 of the Commission's Rules. It is the broadcast station's respon
sibility to ensure that the audio signal applied to a Broadcast Electronics E-Series AM
transmitter conforms to the audio standard NRSC-1 (published as ANSI/EIA-549-1988).
This is a mandatory requirement to ensure that the equipment complies to Section 73.44
and Section 73.128(C) of the Commission's Rules.
BROADCAST ELECTRONICS, INC.

WARNING WARNING
OPERATING HAZARDS
WARNING
WARNING
THE TRANSMITTER CONTAINS MULTIPLE CIRCUIT
GROUNDS WITH HIGH AC AND DC POTENTIALS WITH
RESPECT TO THE CABINET WHICH IS AT EARTH PO
TENTIAL. DO NOT ENERGIZE THE TRANSMITTER
WITH TEST EQUIPMENT CONNECTED TO THE
TRANSMITTER OUTPUT NETWORK, RF POWER MOD
ULE, RF COMBINER, OR POWER SUPPLY COMPO
NENTS.
The Broadcast Electronics AM transmitters contain high voltages and currents. If safety precautions are
not practiced, contact with the high voltages and currents could cause serious injury or death. The trans
mitter is equipped with many built-in safety features, however good judgement, care, and common sense
must be practiced to prevent accidents.
In addition to high voltages and currents, the AM transmitters contain multiple circuit grounds with
high ac and dc potentials with respect to the cabinet which is at earth potential. The potentials could
cause serious injury or death if maintenance personnel simultaneously touch a circuit ground and the
cabinet. As a result, operation of the transmitter with test equipment connected to transmitter output
network, RF power module, RF combiner, or power supply components is extremely dangerous and must
not be attempted. Therefore, never energize the transmitter with test equipment connected to the trans
mitter output network, RF power module, RF combiner, or power supply components. Test equipment
may be connected to the ECU circuit boards from the front of the transmitter using the supplied extender
circuit board with power energized if required.

Broadcast Electronics 1999
ALL RIGHTS RESERVED
Printed in the U.S.A.
-i -
SCOPE OF MANUAL
This manual consists of two sections which provides the following information for the Broadcast
Electronics AM-2.5E and AM-5E AM Broadcast Transmitters.
A. PART I - Contains information relative to installation, operation, and
maintenance applicable to the overall transmitter.
B. PART II - Contains detailed information for the following transmitter
modular units.
1. POWER SUPPLY ASSEMBLY
2. RF POWER MODULE
3. OUTPUT NETWORK
4. EXCITER/CONTROLLER UNIT (ECU)
PART I - TABLE OF CONTENTS
PARAGRAPH PAGE NO.
SECTION I GENERAL INFORMATION
1-1 INTRODUCTION 1-1
1-3 EQUIPMENT DESCRIPTION 1-1
1-4 GENERAL 1-1
1-6 EXCITER/CONTROL UNIT 1-1
1-12 OUTPUT NETWORK ASSEMBLY 1-4
1-13 RF POWER MODULE 1-4
1-15 POWER SUPPLY 1-4
1-16 COMBINER ASSEMBLY 1-4
1-17 TRANSMITTER CONFIGURATIONS 1-5
1-19 ACCESSORIES AND SPARE PARTS KITS 1-5
1-21 EQUIPMENT SPECIFICATIONS 1-5
SECTION II INSTALLATION
2-1 INTRODUCTION 2-1
2-3 UNPACKING 2-1
2-6 ENVIRONMENTAL REQUIREMENTS 2-1
2-8 COOLING AIR REQUIREMENTS 2-1
2-12 PRIMARY POWER 2-1
2-14 INSTALLATION 2-1
2-16 EQUIPMENT PLACEMENT 2-2
2-19 COMPONENT INSTALLATION 2-2
2-22 ECU CIRCUIT BOARDS 2-2
2-23 RF POWER MODULES 2-2
2-24 POWER SUPPLY 2-7
2-25 BATTERY INSTALLATION 2-8
2-26 CIRCUIT BOARD PROGRAMMING 2-8
2-28 EXCITER CIRCUIT BOARD 2-8
2-37 STEREO CIRCUIT BOARD 2-12
2-42 CONTROLLER CIRCUIT BOARD 2-12

-ii -
PARAGRAPH PAGE NO.
2-55 POWER SUPPLY CIRCUIT BOARD 2-15
2-58 REMOTE CONTROL 2-16
2-59 GENERAL 2-16
2-84 WIRING 2-20
2-86 AUDIO INPUT CONNECTION 2-20
2-88 EXTERNAL STEREO RF INPUT 2-20
2-89 AM-2.5E/AM-5E RF TRANSMISSION 2-20
LINE CONNECTION
2-90 EXTERNAL INTERLOCK 2-20
2-91 MODULATION MONITOR 2-20
2-92 AC POWER CONNECTIONS 2-22
2-95 GROUND 2-22
2-96 TRANSMITTER SITE LIGHTNING PROTECTION 2-22
SYSTEM CHECKOUT
2-98 ANTENNA BALL-GAP LIGHTNING ARRESTOR 2-25
2-102 ANTENNA-TUNING-UNIT SPARK-GAP 2-25
LIGHTNING ARRESTOR
2-103 TRANSMITTER SITE GROUNDING SYSTEM 2-25
2-104 CABLE PROTECTION 2-26
2-110 ANTENNA RF FEED LINE 2-26
2-111 TRANSMISSION LINE AND ANTENNA CHECKOUT 2-26
2-113 ANTENNA VSWR 2-26
2-114 COAXIAL SWITCH CONTROLLER 2-26
2-115 ATU AND PHASOR CHECKOUT 2-28
2-116 INITIAL CHECKOUT 2-28
2-118 PRELIMINARY OPERATION AND ADJUSTMENT 2-28
2-120 TUNING 2-28
2-126 POWER LEVEL AND MODULATION MONITOR 2-29
CALIBRATION ADJUSTMENTS
2-138 STEREO ADJUSTMENT 2-30
2-149 SINGLE CHANNEL LEVEL 2-32
SECTION III OPERATION
3-1 INTRODUCTION 3-1
3-3 CONTROLS AND INDICATORS 3-1
3-5 OPERATION 3-12
3-6 TURN-ON 3-12
3-14 TURN OFF 3-13
3-16 METERING 3-13
3-17 FORWARD POWER 3-13
3-18 REFLECTED POWER 3-13
3-19 POWER ADJUST 3-13
3-21 MONO/STEREO OPERATION 3-14
3-23 STEREO OPERATION 3-14
3-24 MONO OPERATION 3-14
3-27 PILOT CONTROL 3-14
3-29 EXCITER MONITOR OPERATION 3-14
3-31 MONO/STEREO INDICATIONS 3-14
3-32 INPUT SELECTION 3-14
3-33 POLARITY SELECTION 3-15
3-34 X10 AUTORANGE INDICATIONS 3-15

-iii-
PARAGRAPH PAGE NO.
3-35 FAULT RESET 3-15
3-37 POWER SUPPLY FAULT RESET 3-15
3-39 OVER-CYCLE OFF 3-15
3-41 OVER-MODULATION PWM MUTE 3-15
3-43 TRANSMITTER MONITOR 3-15
3-45 BATTERY TEST 3-15
3-47 CONTROLLER PWM MUTE INDICATOR 3-16
3-49 CONTROLLER REMOTE FAIL-SAFE INDICATOR 3-16
3-51 EXCITER LOCK INDICATOR 3-16
3-53 EXCITER +5V/+15V/-15V INDICATORS 3-16
3-55 STEREO EQUALIZATION INDICATORS 3-16
3-57 RF POWER MODULE INDICATORS 3-16
3-59 POWER SUPPLY INDICATORS 3-16
3-61 EXCITER NEGATIVE LIMITER INDICATOR 3-16
3-63 HIGH/LOW AC LINE CONDITIONS 3-16
SECTION IV THEORY OF OPERATION
4-1 INTRODUCTION 4-1
4-5 FUNCTIONAL DESCRIPTION 4-1
4-6 ECU 4-1
4-7 GENERAL 4-1
4-8 STEREO CIRCUIT BOARD 4-1
4-11 EXCITER CIRCUIT BOARD 4-1
4-13 CONTROLLER CIRCUIT BOARD 4-2
4-18 POWER SUPPLY 4-2
4-19 RF POWER MODULE 4-2
4-24 RF COMBINER 4-7
4-27 OUTPUT NETWORK 4-7
4-31 POWER SUPPLY 4-8
4-34 POWER SUPPLY CIRCUIT BOARD 4-8
4-39 METERING 4-9
4-42 COOLING FANS 4-9
4-44 INTERFACE CIRCUIT BOARD (AM-5E ONLY) 4-9
4-46 DETAILED DESCRIPTION 4-9
4-47 POWER SUPPLIES 4-9
4-49 AC INPUT CIRCUITRY 4-9
4-53 ECU POWER SUPPLY ASSEMBLY 4-10
4-57 TRANSMITTER FLUSHING FANS 4-10
4-60 LOW-VOLTAGE POWER SUPPLY TRANSFORMER 4-10
4-62 POWER SUPPLY CIRCUIT BOARD 4-10
4-65 CONVENTIONAL RECTIFIER CIRCUITRY 4-13
4-68 SWITCHING POWER SUPPLY CIRCUIT 4-13
4-76 MODULATOR CIRCUIT BOARD 4-14
4-81 POWER AMPLIFIER CIRCUIT BOARDS 4-15
4-86 SEQUENCE OF OPERATION 4-15
4-91 RF CIRCUITRY 4-16
4-92 EXCITER CIRCUIT BOARD 4-16
4-98 STEREO CIRCUIT BOARD 4-17
4-102 RF POWER MODULE 4-17
4-109 RF COMBINER 4-21
4-110 HARMONIC BAND-PASS FILTER 4-22

-iv-
PARAGRAPH PAGE NO.
4-111 DIRECTIONAL COUPLER CIRCUIT BOARD 4-22
4-115 T-MATCHING NETWORK 4-22
4-116 LIGHTNING PROTECTION CIRCUIT BOARD 4-22
4-117 LIGHTNING DETECTION CIRCUIT BOARD 4-23
4-119 RF OUTPUT POWER CONTROL CIRCUITRY 4-23
SECTION V MAINTENANCE
5-1 INTRODUCTION 5-1
5-3 SAFETY CONSIDERATIONS 5-1
5-6 FIRST LEVEL MAINTENANCE 5-1
5-8 ROUTINE MAINTENANCE 5-1
5-9 INSPECTION AND CLEANING 5-2
5-10 CONTROLLER BATTERY 5-2
5-11 AIR FILTERS 5-2
5-12 FLUSHING FANS 5-2
5-14 SPARK GAP 5-2
5-15 SECOND LEVEL MAINTENANCE 5-2
5-18 ELECTRICAL ADJUSTMENTS 5-4
5-20 TRANSMITTER FREQUENCY RE-PROGRAMMING 5-4
5-22 TROUBLESHOOTING 5-4
5-24 TRANSMITTER INDICATORS 5-5
5-25 RF POWER MODULE REMOVAL 5-8
5-26 TRANSMITTER TROUBLESHOOTING 5-8
PROCEDURES
5-27 TRANSMITTER COMPONENT LOCATIONS 5-8
5-28 COMPONENT REPLACEMENT PROCEDURE 5-13
5-34 INTEGRATED CIRCUITS 5-14
SECTION VI PARTS LIST
6-1 INTRODUCTION 6-1
SECTION VII DRAWINGS
7-1 INTRODUCTION 7-1
LIST OF TABLES
TABLE DESCRIPTION PAGE NO.
1-1 ELECTRICAL CHARACTERISTICS 1-5
1-2 PHYSICAL AND ENVIRONMENTAL 1-9
CHARACTERISTICS
3-1 AM-2.5E/AM-5E CONTROLS AND INDICATORS 3-1
3-2 ECU CONTROLS AND INDICATORS 3-3
3-3 POWER MODULE CONTROLS AND INDICATORS 3-11
5-1 AM-2.5E/AM-5E INDICATORS 5-5
5-2 AM-2.5E/AM-5E TROUBLESHOOTING 5-9
6-1 AM-2.5E/AM-5E REPLACEABLE PARTS LIST INDEX 6-1

-v -
LIST OF ILLUSTRATIONS
FIGURE DESCRIPTION PAGE NO.
1-1 AM-2.5E TRANSMITTER 1-2
1-2 AM-5E TRANSMITTER 1-3
2-1 AM-2.5E TRANSMITTER INSTALLATION 2-3
2-2 AM-5E TRANSMITTER INSTALLATION 2-5
2-3 TRANSMITTER MOVING 2-7
2-4 COMPONENT INSTALLATION 2-9
2-5 EXCITER CIRCUIT BOARD PROGRAMMING 2-11
2-6 STEREO CIRCUIT BOARD PROGRAMMING 2-13
2-7 CONTROLLER CIRCUIT BOARD PROGRAMMING 2-14
2-8 REMOTE CONTROL AND AUDIO CONNECTIONS 2-17
2-9 AM-2.5E/AM-5E RF OUTPUT CONNECTIONS 2-21
2-10 AM-2.5E PRIMARY AC WIRING 2-23
2-11 AM-5E PRIMARY AC WIRING 2-24
2-12 ANTENNA LIGHTNING PROTECTION SYSTEM 2-27
2-13 TEST EQUIPMENT CONNECTIONS, POWER LEVEL 2-30
CALIBRATION
2-14 TEST EQUIPMENT CONNECTIONS, SEPARATION 2-31
2-15 EQUALIZATION LISSAJOUS PATTERNS 2-33
3-1 AM-2.5E/AM-5E CONTROLS AND INDICATORS 3-2
3-2 ECU CONTROLS AND INDICATORS 3-7
3-3 POWER MODULE CONTROLS AND INDICATORS 3-11
4-1 AM-2.5E BLOCK DIAGRAM 4-3
4-2 AM-5E BLOCK DIAGRAM 4-5
4-3 AM-2.5E/AM-5E POWER SUPPLY SIMPLIFIED 4-11
SCHEMATIC
4-4 AM-2.5E/AM-5E RF CIRCUITRY SIMPLIFIED 4-18
SCHEMATIC
5-1 REMOVING THE AIR FILTER 5-3
5-2 AM-2.5E COMPONENT LOCATOR 5-15
5-3 AM-5E COMPONENT LOCATOR 5-18
5-4 AM-2.5E/AM-5E ECU/POWER BLOCK/OUTPUT 5-21
NETWORK ASSEMBLY COMPONENT LOCATOR
PART II - TABLE OF CONTENTS
I - POWER SUPPLY ASSEMBLY
II - RF POWER MODULE
III - OUTPUT NETWORK
IV - EXCITER/CONTROLLER UNIT (ECU)

1-1
SECTION I
GENERAL INFORMATION
1-1. INTRODUCTION.
1-2. Information presented by this section provides a general description of the Broadcast
Electronics AM-2.5E and AM-5E transmitters and lists equipment specifications.
1-3. EQUIPMENT DESCRIPTION.
1-4. GENERAL.
1-5. The Broadcast Electronics AM-2.5E transmitter is a CE compliant 2.5 kW solid-state
C-QUAMstereo AM transmitter designed for continuous operation in the 522 kHz to
1705 kHz broadcast band (refer to Figure 1-1). The Broadcast Electronics AM-5E trans
mitter is a CE compliant 5 kW solid-state C-QUAMstereo AM transmitter designed for
continuous operation in the 522 kHz to 1705 kHz broadcast band (refer to Figure 1-2). The
AM-2.5E and AM-5E transmitters consists of modular components assembled in a single
cabinet. The modular components include: 1) an exciter/control unit, 2) an output network
assembly, 3) power block assemblies containing two RF power modules and a star combiner
assembly, 4) power supply panel assemblies, and 5) an AC distribution panel assembly.
Specific AM-2.5E/AM-5E features include:
1. Built-in C-QUAMAM stereo circuitry.
2. High efficiency Class E solid-state RF power amplifier modules.
3. A high efficiency switching power supply.
4. Star combiner assembly. Each star combiner allows the removal of RF power mod-
ules without the use of dummy modules or bypass switches.
5. A built-in output matching network.
6. A CMOS digital controller with extensive VSWR detection and foldback circuitry
which reduces carrier interruptions by weather conditions.
7. CE compliant design.
1-6. EXCITER/CONTROL UNIT. The transmitter exciter/control unit (ECU) is a modular as
sembly containing plug-in stereo, exciter, and controller circuit boards. In addition to the
circuit boards, the ECU is equipped with forward and reflected power meters to provide
transmitter output power status indications.
1-7. Stereo Circuit Board. The ECU stereo circuit board is a modular plug-in assembly con
taining C-QUAMAM stereo circuitry. The C-QUAMstereo system is a mode of AM
stereo transmission utilizing amplitude modulated monaural (L+R) information and inde
pendently quadrature modulated stereo (L-R) information. The results produce a stereo
transmission system compatible with mono receivers.
1-8. The stereo circuit board is designed with remote/local controlled mono left, mono right,
mono L+R, and stereo modes of operation. Two equalization circuits are provided to allow
the transmitter to be configured for operation into two different antennas.
C-QUAMis a registered trademark of Motorola Inc.

1-2
FIGURE 1-1. AM-2.5E TRANSMITTER
597-1114-1
COPYRIGHT 1999 BROADCAST ELECTRONICS, INC

1-3
COPYRIGHT 1999 BROADCAST ELECTRONICS, INC
597-1114-2
FIGURE 1-2. AM-5E TRANSMITTER

1-4
1-9. Exciter Circuit Board. The ECU exciter circuit board is a modular plug-in exciter assem
bly. Instrumentation amplifiers provide balanced left and right channel transformerless
audio inputs. The exciter carrier frequency is established by a digital frequency synthesiz
er. The synthesizer is a phase-locked-loop circuit which provides extremely accurate and
reliable carrier frequency operation. A PWM (pulse-width-modulation) circuit is used to
generate an RF drive signal for application to a modulator circuit board in an RF power
module. If a stereo circuit board failure is encountered or when the stereo circuit board is
removed from the ECU chassis, the exciter circuitry is designed to automatically configure
to monophonic operation.
1-10. Controller Circuit Board. All transmitter control operations are directed by the ECU con
troller circuit board. The controller circuit board consists of CMOS logic control and moni
toring circuitry. The circuitry is designed to interface to all popular remote control systems
such as the Broadcast Electronics VMC-16 remote control system.
1-11. The transmitter power is controlled by a power control circuit. The circuit allows the
transmitter to be operated at five power levels. A power trim circuit allows the transmitter
output power to be adjusted to a precise level. An antenna interlock circuit is provided to
prevent the transmitter from operating into an incorrect antenna. A reflected power detec
tion circuit operates in association with the power control circuit to foldback the transmit
ter power during high VSWR conditions. In addition to the reflected power detector, a
lightning detector circuit is provided to mute the transmitter when high voltage is present
at the transmitter output during a lightning storm.
1-12. OUTPUT NETWORK ASSEMBLY. Matching of the transmitter impedance to the antenna is
accomplished by the output network assembly. The assembly is equipped with an
LC T network to match the transmitter output to the antenna. A bandpass filter is pro
vided to attenuate all harmonic frequencies to FCC, DOC, and CCIR levels. The assembly
also contains the lightning detection circuit board, a lightning protection circuit board, and
a directional coupler assembly.
1-13. RF POWER MODULE. The AM-2.5E and AM-5E transmitters are equipped with RF pow
er modules. A power module is a modular plug-in assembly containing two RF power am
plifier circuit boards and one modulator circuit board. Each power module is equipped
with MOSFET transistors to produce approximately 1375 watts of RF power.
1-14. The RF power modules are designed using Class E amplifier technology. A Class E ampli
fier exhibits high efficiency and provides superior audio performance. In addition to the
superior efficiency and audio performance, the power modules are designed to be removed
from the chassis for maintenance. The remaining power modules will provide full power to
maintain on-air operation.
1-15. POWER SUPPLY. A modular switching power supply provides operating potentials for two
RF power modules. The power supply design uses an SCR controlled bridge to rectify the
ac line voltage into a dc potential. The supply is filtered and routed to the RF power mod
ules for control and regulation. A fault detection circuit monitors power supply activity for
failure conditions. A separate modular switching power supply provides operating poten
tials for the ECU circuitry.
1-16. COMBINER ASSEMBLY. The AM-2.5E and AM-5E are equipped with a star combining
system. The system combines the outputs of the RF power modules to provide: 1) a 2.5
kW output in AM-2.5E models and 2) a 5 kW output in AM-5E models. If a power module
is removed from the chassis, the remaining power modules will continue operation to main
tain on-air operation.

1-5
1-17. TRANSMITTER CONFIGURATIONS.
1-18. The AM-2.5E and AM-5E transmitters can be ordered in the following configurations:
P/N DESCRIPTION
907-2500-100 AM-2.5E 2.5 kW AM Transmitter for operation in
the 522 kHz to 1705 kHz broadcast band, 10 kHz
spacing, 196V - 256V ac single phase supply.
907-5000-100 AM-5E 5 kW AM Transmitter for operation in
the 522 kHz to 1705 kHz broadcast band, 10 kHz
spacing, 196V - 256V ac single phase supply.
1-19. ACCESSORIES AND SPARE PARTS KITS.
1-20. The following text presents accessories and spare parts kits available for use with the
AM-2.5E and AM-5E transmitters.
P/N DESCRIPTION
977-0038 AM-2.5E/AM-5E recommended semi-conductor
kit.
977-0039 AM-2.5E 100% semi-conductor kit.
977-0040 AM-2.5E/AM-5E recommended spare parts kit.
Includes selected meters, switches, fuses, filters,
etc. Does not include semi-conductors.
977-0041 AM-5E 100% semi-conductor kit.
907-0016-110 VMC-16 Voice Remote Control Unit, AM-10A/
AM-6A/AM-2.5E/AM-5E.
977-0037 Basic semi-conductor kit, AM-10A/AM-6A/
AM-1A/AM-2.5E/AM-5E.
1-21. EQUIPMENT SPECIFICATIONS.
1-22. Refer to Table 1-1 for electrical specifications or Table 1-2 for physical specifications of the
AM-2.5E and AM-5E transmitters.
TABLE 1-1. ELECTRICAL CHARACTERISTICS
(Sheet 1 of 5)
PARAMETER SPECIFICATION
RF POWER OUTPUT
AM-2.5E 12.5 W to 2.8 kW. Five preset power levels
available by local or remote control. Will operate
at a reduced power output (30-50% typical) with
one-half of the power modules.
AM-5E 25 W to 5.6 kW. Five preset power levels
available by local or remote control. Will operate
at a reduced power output (30-50% typical) with
one-half of the power modules.

1-6
TABLE 1-1. ELECTRICAL CHARACTERISTICS
(Sheet 2 of 5)
PARAMETER SPECIFICATION
OUTPUT POWER REGULATION Less than 1% change in output power with vari-
ation of ac line input voltage from 196V to 252V
ac.
RF CARRIER FREQUENCY 522 kHz to 1705 kHz (as ordered).
RANGE Accommodates 9 kHz or 10 kHz channel spacing
(9 kHz spacing requires an optional crystal).
RF OUTPUT IMPEDANCE 50 Ohms, unbalanced. Matching network to
optimize VSWR of 1.5 : 1 at any phase angle and
carrier frequency.
OUTPUT CONNECTOR Female 7/16 DIN connector.
AM-5E Requires 7/8 inch RF transmission line with 7/16
male DIN connector.
AM-2.5E Requires 1/2 inch RF transmission line with 7/16
male DIN connector.
LOAD VSWR 1.5 : 1 at full carrier power. Will operate into a
higher VSWR with automatic power reduction.
Open and short circuit protected.
HARMONIC AND SPURIOUS Meets or exceeds FCC, DOC, and CCIR require-
SUPPRESSION ments when preceded by external NRSC-1 com-
patible audio low-pass filters.
CARRIER FREQUENCY ±3ppm, 0°to 50°C (+32°to +122°F).
STABILITY
CARRIER SHIFT Less than 1% at 95% negative modulation at
1 kHz.
TYPE OF MODULATION Pulse Width Modulation of L+R envelope with
integrated C-QUAM AM stereo. An RF input
connector is also provided for an external stereo
exciter.
OPERATING MODES Stereo, mono L+R, mono L, mono R, by local or
remote control.
MODULATION CAPABILITY
AM-2.5E Greater than 145% peak positive capability at
2.5 kW.
AM-5E Greater than 145% peak positive capability at
5 kW.
MODULATION INPUT INDICATION Peak reading, color coded, LED bar graph display
with an autorange feature for monitoring positive
or negative input levels of four different audio
channels (L/R or L+R/L-R).
AUDIO INPUT LEVEL +10 dBm, ±1 dB, L=R (or mono) to produce 100%
L+R envelope modulation. Other input levels can
be accommodated.

1-7
TABLE 1-1. ELECTRICAL CHARACTERISTICS
(Sheet 3 of 5)
PARAMETER SPECIFICATION
AUDIO INPUT IMPEDANCE 600 Ohms. Inputs are balanced, transformerless,
and resistive with passive RFI filtering. Other
impedances can be accommodated.
AUDIO FREQUENCY ±0.5 dB, 20 Hz to 10 kHz at 90% negative
RESPONSE (MONOPHONIC) modulation (linear phase mode). +0.1 dB
-3 dB, 20 Hz to 10 kHz at 90% negative
modulation, standard configuration.
AUDIO HARMONIC DISTORTION
Mono Less than 0.8%, 20 Hz to 10 kHz at rated power.
Less than 1.5%, 20 Hz to 10 kHz at 50% power.
Less than 2.0%, 20 Hz to 10 kHz at 25% power.
Less than 3.0%, 20 Hz to 10 kHz at 10% power.
All mono audio harmonic distortion specifications
are referenced to an audio input level which
generates 90% modulation at 1 kHz (9 dBm).
Stereo Less than 1.5% at 50% single channel
modulation, 50 Hz to 10 kHz at rated power.
INTERMODULATION DISTORTION 1.2% or less at 1:1 ratio. 1.7% or less at 4:1 ratio.
(MONO) 60/7000 Hz SMPTE standards with 85%
modulation at rated power.
CCIF INTERMODULATION 1.0% or less at 1:1 ratio. 4 kHz/5 kHz with 85%
DISTORTION (MONO) modulation at rated power.
TRANSIENT INTERMODULATION 1.0% or less at 4:1 ratio. 2.96 kHz square wave
DISTORTION (MONO) 8 kHz sinewave with 85% modulation at rated
power.
INCIDENTAL PHASE Less than 2.0 degrees (0.035 radians) average or 30
MODULATION dB (40 dB typical) below equivalent 100% L-R
(STEREOPHONIC) C-QUAM modulation, 50 Hz to 10 kHz at rated
power. Measured with an audio input level which
generates 95% negative L+R envelope modulation
at 1 kHz (9.5 dBm).
STEREO SEPARATION -30 dB or greater, 50 Hz to 10 kHz. Measured
with 50% single channel modulation into a 50 ohm
resistive load at rated power.
SQUAREWAVE OVERSHOOT
Mono 0.1% or less at 400 Hz, 90% modulation with high
frequency boost disabled.
Stereo 1.0% or less at 400 Hz, 50% single channel modu-
lation with high frequency boost disabled.

1-8
TABLE 1-1. ELECTRICAL CHARACTERISTICS
(Sheet 4 of 5)
PARAMETER SPECIFICATION
SQUAREWAVE TILT 1.0% or less at 40 Hz. 1.5% or less at 20 Hz.
Measured with 90% negative modulation.
NOISE
Mono Greater than 65 dB below a reference level
equivalent to 100% negative modulation in a 22
Hz to 30 kHz bandwidth, unweighted.
Stereo Greater than 55 dB below a reference level
equivalent to 100% negative modulation of
either left or right channel in a 22 Hz to
30 kHz bandwidth, unweighted.
AC INPUT VOLTAGE 196V to 252V ac 50/60 Hz, single phase.
Includes built-in MOVs for surge suppression.
AC POWER CONSUMPTION
AM-2.5E 3.3 kW, no modulation of 2.5 kW carrier.
2.05 kW, 100% modulation of 2.5 kW carrier.
Measured at 2.5 kW into a 50 ohm resistive
load at 220V ac. 0.9 power factor.
AM-5E 6.7 kW, no modulation of 5 kW carrier.
10 kW, 100% modulation of 5 kW carrier.
Measured at 5 kW into a 50 ohm resistive
load at 220V ac. 0.9 power factor.
OVERALL EFFICIENCY
AM-2.5E 75% or greater, 100% sinusoidal modulation
of carrier, ac line to RF output. Measured
at into 2.5 kW a 50 ohm resistive load at
220V ac.
AM-5E 75% or greater, 100% sinusoidal modulation of
carrier, ac line to RF output. Measured at 5 kW
into a 50 ohm resistive load at 220V ac.
SAFETY Meets IEC 215 specifications.
REGULATORY Meets CE specifications.
METERING
AM-2.5E Output Forward Power: 1) High scale - 0 to
3000 watts and 2) Low scale - 0 to 750 watts.
Output Reflected Power: 1) High scale - 0 to 300
watts and 2) Low scale - 0 to 60 watts. Ac Line
Voltage: Scale - 150 to 300 volts. AM-2.5
Forward Power Meter complies with FCC rule
78.1215 (a) within the 150 watt to 2800 watt range.

1-9
TABLE 1-1. ELECTRICAL CHARACTERISTICS
(Sheet 5 of 5)
PARAMETER SPECIFICATION
METERING (CONT'D)
AM-5E Output Forward Power: 1) High scale - 0 to 6000
watts and 2) Low scale - 0 to 1500 watts.
Output Reflected Power: 1) High scale - 0 to
600 watts and 2) Low scale - 0 to 150 watts. Ac
Line Voltage: Scale - 150 to 300 volts. AM-5
Forward Power Meter complies with FCC rule
73.1215 (a) within the 300 watt to 5600 watt
range.
RF MONITORING PROVISIONS 2 volts RMS nominal RF output sample into a 50
Ohm input. Adjustable from the transmitter
front panel for each of the five power levels.
REMOTE INTERFACE Built-in interface for most control and monitoring
systems.
TABLE 1-2. PHYSICAL AND ENVIRONMENTAL CHARACTERISTICS
(Sheet 1 of 2)
PARAMETER SPECIFICATION
PHYSICAL
DIMENSIONS Width: 24.82 Inches (63.0 cm).
Height: 71.32 Inches (181.2 cm)
Depth: 31.55 Inches (80.1 cm)
WEIGHT
AM-2.5E 410 Pounds (186 kg), unpacked.
AM-5E 525 Pounds (238 kg), unpacked.
CUBAGE 42.8Ft3(1.2 m3).
ENVIRONMENTAL
COOLING
Type Low velocity air with disposable filters.
Requirements - AM2.5E/AM-5E 500 Cubic Feet Per Minute (14.15 m3/min).
OPERATING TEMPERATURE 0°to 50°C (+32°to +122°F)
OPERATING HUMIDITY 0 TO 95% (non-condensing)

1-10
TABLE 1-2. PHYSICAL AND ENVIRONMENTAL CHARACTERISTICS
(Sheet 2 of 2)
PARAMETER SPECIFICATION
MAXIMUM ALTITUDE
60 Hz Models 0 to 10,000 feet above sea level (0 to 3048 Meters).
50 Hz Models 0 to 7,500 feet above sea level (0 to 2286 Meters).
NOTE -
For AM-2.5E, All specifications measured at 2.5 kW into a 50 ohm resistive load using
Broadcast Electronics AS-10 modulation monitor.
For AM-5E, All specifications measured at 5 kW into a 50 ohm resistive load using
Broadcast Electronics AS-10 modulation monitor.

2-1
SECTION II
INSTALLATION
2-1. INTRODUCTION.
2-2. This section contains information required for the installation and preliminary checkout of
the Broadcast Electronics AM-2.5E and AM-5E transmitters.
2-3. UNPACKING.
2-4. The equipment becomes the property of the customer when the equipment is delivered to
the carrier. Carefully unpack the transmitter. Perform a visual inspection to determine
that no apparent damage has been incurred during shipment. All shipping materials
should be retained until it is determined that the unit has not been damaged. Claims for
damaged equipment must be promptly filed with the carrier or the carrier may not accept
the claim.
2-5. The contents of the shipment should be as indicated on the packing list. If the contents are
incomplete, or if the unit is damaged electrically or mechanically, notify both the carrier
and Broadcast Electronics.
2-6. ENVIRONMENTAL REQUIREMENTS.
2-7. Table 1-2 provides environmental conditions which must be considered prior to transmit
ter installation. Refer to Table 1-2 in SECTION I, INTRODUCTION and ensure the
transmitter is to be installed in an acceptable environment.
2-8. COOLING AIR REQUIREMENTS.
2-9. If outside air is to be used to cool the transmitter, the air inlet duct must be sized to allow
adequate air flow. The air must be dry and well filtered. If intake louvers are used, opera
tion of the louvers must be electrically interlocked with the transmitter operation.
2-10. If the heated transmitter air is to be ducted from the room, the duct system must not
introduce any back-pressure on the equipment. Proper allowances for air flow will ensure
that only a limited amount of heat is dissipated into the equipment interior. The duct sys
tem must allow for a minimum air flow of: 1) 500 cubic feet of air per minute for AM-2.5E
models and 2) 700 cubic feet of air per minute for AM-5E models.
2-11. As a minimum requirement, any duct work must have a cross-sectional area equal to the
exhaust area of the cabinet (refer to Figure 2-1 and 2-2). Sharp bends in the duct system
will introduce back pressure and are not permissible. A radius bend must be used if a
right angle turn is required. An exhaust fan may be used to overcome duct losses or over
come wind pressures if the duct is vented to the outside.
2-12. PRIMARY POWER.
2-13. The AM-2.5E and AM-5E transmitters are designed for operation from a 196V to 252V ac
50/60 Hz single phase power source. Consult the local electric utility company to ensure
that the correct service is provided before connection of the transmitter to the primary
power source.
2-14. INSTALLATION.
2-15. Each transmitter is wired, operated, tested, and inspected at the factory prior to shipment
and is ready for installation when received. Prior to installation, this publication should be
studied to obtain an understanding of the operation, circuitry, nomenclature, and installa
tion requirements. Installation is accomplished as follows: 1) placement, 2) component
installation, 3) circuit board programming, 4) remote control connections, 5) wiring,
6) initial checkout, and 7) preliminary operation and tuning.