Harris MW-SB User manual

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T.M. No. 888-2109-014
© Copyright Harris Corporation
1985
All rights reserved
994
8622 001
TECHNICAL MANUAL
MW-SB
AM BROADCAST TRANSMITTER
888-2109-014
Printed : January 23, 1985

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Returns And Exchanges
Damaged or undamaged equipment should not be returned unless written approval c··
and a Return Authorization is received from HARRIS CORPORATION, Broadcast
Systems Division. Special shipping instructions and coding will be provided to as-
sure proper handling. Complete details regarding circumstances and reasons for
return are to be included in the request for return. Custom equipment
or special
order equipment is not returnable.
In those instances where return or exchange of
equipment is at the request of the customer, or convenience of the customer, a
restocking fee will
be charged. All returns will be sent freight prepaid and properly
insured by the customer. When communicating with HARRIS CORPORATION,
Broadcast Systems Division, specify the HARRIS Order Number or Invoice
Number. Unpacking
Carefully unpack the equipment and preform a visual inspection to determine that
no apparent damage was incurred during shipment. Retain the shipping materials
until it has been determined that all received equipment is not damaged. Locate
and retain all PACKING CHECK LISTs. Use the PACKING CHECK LIST to help
locate and identify any components or assemblies which are removed for shipping
and must be reinstalled. Also remove any shipping supports, straps, and packing
materials prior to initial turn on.
Technical Assistance
HARRIS Technical and Troubleshooting assistance is available from HARRIS Field
Service during normal business hours (8:00
AM -5:00 PM Central Time). Emer-
gency service is available 24 hours a day. Telephone [phone] to contact the (
Field Service Department or address correspondence to Field Service Department, ·
HARRIS CORPORATION, Broadcast Systems Division, P.O. Box 4290, Quincy, Illi-
nois 62305-4290, USA. The HARRIS factory may also be contacted through a FAX
facility (217/221-7096). Replaceable Parts Service
Replacement parts are available 24 hours a day, seven days a week from the
HARRIS Service Parts Department. Telephone [phone] to contact the service
parts department or address correspondence to Service Parts Department, HAR-
RIS CORPORATION, Broadcast Systems Division, P.O. Box 4290, Quincy, Illinois
62305-4290, USA. The HARRIS factory may also
be contacted through a FAX fa-
cility (217/221-7096). ·
NOTE
The# symbol used in the parts list means·used with (e.g. #COO! = used with COO!).
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Guide to Using Harris Parts List Information
Toe Harris Replaceable Parts List Index portrays a tree structure with the major items being leftmost in the index.
Toe example below shows the Transmitter
as the highest item in the tree structure. If you were to look at the bill of
.materials table for the Transmitter you would find the Control Cabinet, the PA Cabinet, and the Output Cabinet. In
---J:he Replaceable Parts List Index the Control Cabinet, PA Cabinet, and Output Cabinet show up one indentation level
below the Transmitter and implies that they are used
in the Transmitter. Toe Controller Board is indented one level
below the Control Cabinet
so it will show up in the bill of material for the Control Cabinet. Toe tree structure of this
same index is shown to the right
of the table and shows indentation level versus tree structure level.
Example of Replaceable Parts List Index and equivalent tree structure:
Table 7-1.
Table 7-2.
Table 7-3.
Table 7-4.
Table 7-5.
Table 7-6.
Table 7-7.
Reolaceable Ports List Index
Transmitter 994 9283 001
Control Cabinet
992 9244 002
Controller Boord 992 8344 002
PA Cabinet 992 9400 002
PA Amplifier 994 7894 002
PA Amplifier Boord 992 7904 002
Output Cabinet 992 9450 001
7-2
I Transmitter I
994 9283 001 I
7-3 IControl CabinetI \ PA Cabinet I \Output Cabinet
7-6 992 9244 0021 992 9400 0021 992 9450 001
7-7 ⇒ T
7-9 \Controller Board! I PA Amplifier I
7-10 992 8344 002 I 994 7894 0021
7-12
I
PA Amplifier Board!
992 7904 002 I
Toe part number of the item is shown to the right of the description as is the page in the manual where the bill for
that part number starts.
Inside the actual tables, four main headings are used:
Table#-#. ITEM NAME -HARRIS PART NUMBER -this line gives the information that corresponds to the
Replaceable Parts List Index entry;
HARRIS
PIN column gives the ten digit Harris partnumber (usually in ascending order);
DESCRIPTION column gives a 25 character or less description
of the part number;
REF. SYMBOLS/EXPLANATIONS column
1) gives the reference designators for the item (i.e., COO!, R102,
etc.) that corresponds to the number found in the schematics
(COOi in a bill of material is equivalent to Cl on the
schematic)
or 2) gives added information or further explanation (i.e., "Used for 208V operation only," or "Used
for
HT lOLS only," etc.).
Inside the individual tables some standard conventions are used:
A# symbol in front of a component such as #COOi under the REF. SYMBOLS/EXPLANATIONS column means
that this item is used on or with
COOi and is not the actual part number for COOL
In the ten digit part numbers, if the last three numbers are 000, the item is a part that Harris has purchased and
has not manufactured or modified. If the last three numbers are other than 000, the item is either manufactured by
Harris or is purchased from a vendor and modified for use
in the Harris product.
Toe first three digits
of the ten digit part number tell which family the part number belongs to -for example, all
electrolytic (can) capacitors will
be in the same family (52± xxxx 000). If an electrolytic (can) capacitor is found
to have a 9xx xxxx xxx part number (a number outside of the normal family of numbers), it has probably been
modified
in some manner at the Harris factory and will therefore show up farther down into the individual parts
list (because each table is normally sorted in ascending order). Most Harris made or modified assemblies will
have 9xx xxxx xxx numbers associated with them.
Toe term
"SEE HIGHER LEVEL BILL" in the description column implies that the reference designated part
number will show up in a bill that is higher
in the tree structure. This is often the case for components that may
be frequency determinant or voltage determinant and are called out in a higher level bill structure that is more
customer dependent than the bill at a lower level.
2-02-93

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~SBroodcost
Systems
Division I IHARRIS PHONE:
217-222-8200
P.O. Box
4290,
QUINCY,
IL
62305
PARTS
ORDER
FORM
HARRIS FAX:
217-221-7096
IBILLING
INFORMATION
I ISHIPPING INFORMATION I
CUSTOMER
NAME:
SHIP
TO:
(if
different
from
billing
information)
ADDRESS:
ADDRESS:
TELEPHONE
NUMBER:
TELEPHONE
NUMBER:
FAX
NUMBER:
FAX
NUMBER:
PREFERRED
PAYMENT
METHOD:
SHIPPING
METHOD
PREFERRED:
GUIDE
FOR
ORDERING
PARTS
FREQUENCY
(If
required),
Please use the following ports order form, filling
is
os much informotlon os possible.
The
complete informolton
wlll
allow double checking the port number for correctness or
locating o substitude if the port is not ovoiloble.
EQUIPMENT NAME:
The
equipment name, port number, and sertol number
will
be found on the
metal
10
plate
on
the bock of the unit.
The
serial number
MUST
be Included fof any ports ordered under
EQUIPMENT
PART
NUMBER:
warranty.
Describe the port
ustng
the
descrtpUon
in
the ports list if possible. Include the schemoUc
information, schematic number,
or
number
of
next higher assembly.
The
next higher
EQUIPMENT
SERIAL
NUMBER:
assembly is usually o 992-xxxx-OOx type.
ITEM
USED
ON
DESCRIPTION
OF
PART
SCHEMATIC
REFERENCE
(NEXT
HIGHER
ASSEMBLY IF KNOWN)
(PART'S NAME, DESCRIPTION, SPECIFICATION
REFERENCE
NAME
(e.g.
COOi
used
on
992
8025
001,
COMMENTS
ITEM
8
QTY
HARRIS PART NUMBER
FROM
PARTS LIST IF AVAILABLE) (e.g. COOi, R100,
etc)
SCHEMA
TIC
839
8099
991)
ORD
~.
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MANUAL REVISION HISTORY
MW-SB AM BROADCAST TRANSMITTER
888-2109-xxx
REV. ifo
DATE ECN
PAGES AFFECTED
011 06-06-84 29067
Replaced the following
pages:
Title Page
1-6, 5-13, 5-15, 5-16, 5-28, 5-29, 5-30, 5-31,
5-32
Added the following page:
Manual Revision History page
012
07-31-84
29106 Replaced the following pages:
Title Page, Manual Revision History Page, 7-32
013
10-18-84
29122
Replaced the following pages:
Title Page, Manual Revision History
Page
7-10, 8-11/8-12
014
01-23-85
27944
Replaced the following pages:
Title Page, Manual Revision History
Page,
7-29
888-2109-014

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WARNING
THE .CURRENTS AND VOLTAGES IN THIS EQUIPMENT ARE DANGEROUS.
PERSONNEL MUST AT ALL TIMES OBSERVE SAFETY REGULATIONS.
This manual is intended as a general guide for trained and qualified personnel
who are aware of the dangers inherent in handling potentially hazardous
electrical/electronic circuits. It is not intended to contain a complete
statement of all safety precautions which should be observed by personnel in
using this or other electronic equipment.
The
installation, operation, maintenance and service of this equipment
involves risks both to personnel and equipment, and must be performed only by
qualified personnel exercising due care. HARRIS CORPORATION shall not be
responsible for injury or damage resulting from improper procedures or from
the use of improperly trained or inexperienced personnel performing such tasks,
During installation and operation of this equipment, local building codes and
fire protection standards must be observed. The following National Fire
Protection Association (NFPA) standards are recommended as references:
- Automatic Fire Detectors, No. 72E
- Installation, Maintenance, and Use of Portable Fire Extinguishers,
No. 10
-
Halogenated Fire Extinguishing Agent Systems, No. 12A
WARNING
ALWAYS DISCONNECT POWER BEFORE OPENING COVERS, DOORS,
ENCLOSURES, GATES, PANELS OR SHIELDS. ALWAYS USE GROUND-
ING STICKS AND SHORT OUT HIGH VOLTAGE POINTS BEFORE
SERVICING.. NEVER MAKE INTERNAL ADJUSTMENTS, PERFORM
MAINTENANCE OR SERVICE WHEN ALONE OR WHEN FATIGUED.
Do not remove, short-circuit or tamper with interlock switches on access
covers, doors, enclosures, gates, panels or shields, Keep away from live
circuits, know your equipment and don't take chances.
WARNING
IN CASE OF EMERGENCY ENSURE THAT POWER HAS BEEN
DISCONNECTED.
WARNING
IF OIL FILLED OR ELECTROLYTIC CAPACITORS ARE UTILIZED IN
YOUR EQUIPMENT, AND IF A LEAK OR BULGE IS APPARENT ON THE
CAPACITOR CASE WHEN THE UNIT IS OPENED FOR SERVICE OR
MAINTENANCE, ALLOW THE UNIT TO COOL DOWN BEFORE ATTEMPTING
TO REMOVE THE DEFECTIVE CAPACITOR. DO NOT ATTEMPT TO
SERVICE A DEFECTIVE CAPACITOR WHILE IT IS HOT DUE TO THE
POSSIBILITY OF A CASE RUPTURE AND SUBSEQUENT INJURY.
i

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TREATMENT OF ELECTRICAL SHOCK
1. IF VICTIM IS NOT RESPONSIVE FOLLOW THE A-B-CS OF BASIC LIFE SUPPORT.
PLACE VICTIM FLAT ON HIS BACK ON A HARD SURFACE
@ AIRWAY
IF UNCONSCIOUS.
OPEN AIRWAY
LIFT UP NECK
PUSH FOREHEAD BACK
CLEAR OUT MOUTH IF NECESSARY
OBSERVE FOR BREATHING
CHECK
CAROTID PULSE
@ BREATHING
IF NOT BREATHING.
BEGIN ARTIFICIAL BREATHING
TILT HEAD
PI NCH NOSTRILS
MAKE AIRTIGHT SEAL
4 QUICK FULL BREATHS
REMEMBER MOUTH TO MOUTH
RESUSCITATION MUST BE
COMMENCED AS SOON AS POSSIBLE
© CIRCULATION
DEPRESS STERNUM 1 1/2 TO 2 INCHES
IF PULSE ABSENT.
BEGIN ARTIFICIAL
CIRCULATION
APPROX. RATE {ONE RESCUER
OF COMPRESSIONS 15 COMPRESSIONS
--80 PER t.4 INUTE 2 QUICK BREATHS
APPROX. RATE {TWO RESCUERS
U-'--l------'--1....J
OF COMPRESSIONS 5 COMPRESSIONS
--60 PER MINUTE 1 BREATH
NOTE: DO NOT INTERRUPT RHYTHM OF COMPRESSIONS
WHEN. SECOND PERSON IS GIVING BREATH
CALL FOR MEDICAL ASSISTANCE AS SOON AS POSSIBLE.
2. IF VICTIM IS RESPONSIVE.
A. KEEP THEM WARM
B. KEEP THEM AS QUIET AS POSSIBLE
C. LOOSEN THEIR CLOTHING
0. A RECLINING POSITION IS RECOMMENDED
ii
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FIRST-AID
Personnel engaged in the installation, operation, maintenance or servicing of
this equipment are urged to become familiar with first-aid theory and
practices. The following information is not intended to be complete first-aid
procedures, it is brief and is only to be used as a reference. It is the duty
of all personnel using the equipment to be prepared to give adequate Emergency
First Aid and thereby prevent avoidable loss of life,
Treatment of Electrical Burns
1. Extensive burned and broken skin
a. Cover area with clean sheet or cloth, (Cleanest available cloth
article,)
b. Do not break blisters, remove tissue, remove adhered particles of
clothing, or apply any salve or ointment.
c. Treat victim for shock as required.
d, Arrange transportation to a hospital as quickly as possible,
e. If arms or legs are affected keep them elevated.
NOTE
If medical help will not be available within an
hour and the victim is conscious and not
vomiting, give him a weak solution of salt and
soda: 1 level teaspoonful of salt and 1/2
level teaspoonful of baking soda to each quart
of water (neither hot or cold). Allow victim
to sip slowly about 4 ounces (a half of glass)
over a period of 15 minutes. Discontinue fluid
if vomiting occurs. (Do not give alcohol.)
2. Less severe burns - (1st &2nd degree)
a, Apply cool (not ice cold) compresses using the cleanest available
cloth article.
b, Do not break blisters, remove tissue, remove adhered particles of
clothing, or apply salve or ointment.
c. Apply clean dry dressing if necessary.
d. Treat victim for shock as required.
e. Arrange transportation to a hospital as quickly as possible.
f. If arms or legs are affected keep them elevated.
REFERENCE: ILLINOIS HEART ASSOCIATION
AMERICAN RED CROSS STANDARD FIRST AID AND PERSONAL SAFETY MANUAL
(SECOND EDITION)
888-2109-010
iii

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TABLE OF CONTENTS
Paragraph
1-1.
1-3.
1-10,
1-20.
1-21.
1-23.
2-1.
2-3.
2-7.
2-9.
2-11.
2-14.
2-17.
2-20.
2-21.
2-22.
2-24.
2-26.
2-27.
2-28.
2-29.
2-30.
2-31.
2-32.
2-33.
2-35.
2-37.
2-39.
2-41.
2-43.
2-45.
3-1.
3-3.
3-5.
3-7.
4-1.
4-3.
4-5.
4-7.
4-11.
4-13.
iv
SECTION I. GENERAL DESCRIPTION
Introduction
..................................................
Physical Description••···••·••··•·•·•••••····••••••·••·····•
Functional Description··•··•··•·•··•········••····•··•···•····
Equipment Characteristics···•····•••••••••···••·•··•··········
Electrical Characteristics ••········•·••···••••··········•··
Mechanical/Environmental Characteristics .••••..•......•••••••
SECTION II. INSTALLATION
Introduction
•••••••••••••••••••••••••••••••••••••••••••••• ♦ •••
Incoming Inspection and Unpacking•••••••••••••••••••••••••••••
Returns and Exchanges .•.••.•.•.••••..•.•...••......•..••.••..•
Installation ...................................................... .
Transmitter Installation ............................................... .
Installation of Removed Components ................................. ..
Installation of Variable Capacitor 1Cl4 ••••••••••••••••••·••
4CX3000A Modulator Tube Installation ................................ .
3CX2500F3 Power Amplifier Tube Installation·······•••··•••
External Connections ................................................................... .
Primary Power
.................................................................. ..
RF Output .......................................................................... ..
Audio Input (Normally 600-0hm Balanced)
.. ..................... ..
Modulation Monitor ...................................................................... .
Frequency Monitor ......................................................... .
Transmitter Grounding Stud ................................................ .
External Interlock ........................................................... .
Remote Control Connections
Initial Pre Turn On Mechanical
Initial Pre Turn On Electrical
...............................................
Checks
...............................
Checks .......................................... .
Primary Power
Application .............................................. .
Remote
Me-ter Calibration ....................................................... .
Remote
Plate Current Sample Adjustment ........................................ ..
Remote PA Plate Voltage Meter Sample Calibration ••••••••••••
Remote Ep-Ip Calibration ............................................................... ..
SECTION III.
OPERATION
Introduction
.....................................................................................
Controls and Indicators ................................................................ ..
Operating Procedure .......................................................................... .
Modulation Enhancer~ ........................................................................ ..
General
Overall
SECTION IV.
PRINCIPLES OF OPERATION
......................................................................................................
Functional Description ......................................................... ..
RF Subsystem ............................................................................................. .
Audio Subsystem
............................................................................. ..
Control Subsystem ................................................................................. ..
Personnel and Equipment Protection Subsystem••···••••·•·······
888-2109-010
WARNING: Disconnect primary power prior to servicing.
Page (
1-1
1-1
1-3
1-7
1-7
1-7
2-1
2-1
2-1
2-2
2-2
2-2
2-5
2-12
2-12
2-12
2-12
2-14
2-14
2-14 (
2-14
2-14
2-18
2-18
2-20
2-21
2-22
2-31
2-31
2-33
2-34
3-1
3-1
3-1
3-24
4-1
4-1
4-1
4-1
4-2
4-2
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TABLE OF CONTENTS (Continued)
Paragraph Page
4-15.
4-17.
4-19.
4-21.
4-23.
4-25.
4~27.
4-29.
4-31.
4-33.
4-34.
4-35.
4-43.
4-47.
4-50.
4-51.
4-54.
4-55.
4-56.
4-62.
4-65.
4-66.
4-67.
4-68.
4-69.
4-71.
4-72.
4-73.
4-74.
4-75.
4-76.
4-77.
4-78.
4-79.
4-80.
4-81.
4-82.
4-84.
4-85.
4-90.
4-91.
4-93.
5-1.
5-3.
5-5.
Safety Interlock Circuit
DC Overload
8 0 0 0 0 0 0 0 0 0 0 0 0 ♦ 0 0 0 0 0 ♦ 0 0 0 0 0 0 ♦ 0 0 ♦ 0 e O O O O O O O o O O o 9 O ♦ O O 0
Dissipation Overload•·••••••••••·······•••·······•··········
Modulator Screen Overload 0 0 0 0 O O O O O O O
♦ 0 ♦ 0 0 O O ♦ O ♦ ♦ O ♦ ♦ O O O O O O O ♦ O ♦
VSWR Overload Circuit
Step Start Overload
...........................................
O O O O O O O O ♦ 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ♦ O O O O ♦ O O O O O O O 0
Overload Counter and Turn Off Circuit
0 0 ♦ 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Air Interlock Switch·······•·•··•···•••····•••·•··••··•••••·
HV Transformer Fault
0 0 0 0 0 0 0 ♦ ♦ 0 0 0 0 ♦ 0 0 0 ♦ ♦ 0 0 9 0 ♦ 0 0 0 0 ♦ 0 0 • 0 0 0 ♦ 0 ♦ 0 0
Detailed Description of Circuits
0 0 0 0 ♦ ♦ ♦ 0 0 0 0 ♦ t ♦ ♦ ♦ ♦ ♦ O ♦ ♦ O O O O O ♦ 0 ♦ ♦
RF Subsystem ,. ............................................... ..
Oscillator Module 1A2Al •··••·••·······•··········•••···•··
0 0 0 0 0 0 ♦ 0 0 0 0 0 0 0 ♦ ♦ ♦ ♦ 0 • 0 0 0 0 0 0 Cl O .... • ••
IPA and RF Drivers, 1A2A3
Power Amplifier Grid Circuit
............................................
Audio Subsystem ........................................................................ ..
....................................................................
Modulation Enhancer
PDM and Audio Driver,
Principles of Pulse
1A1 ............................................. .
Duration Modulation ........................ ..
PDM Board,
lAlAl ........................................................... .,,, ...
Audio Driver Board, 1A1A3
.......................................
.................................................
Modulator Tube Circuit
Modulator Tube
........................................................
75 kHz Filter
..........................................................
Damper Diode Assembly••••••••
Audio Input, Dissipation Overload,
......................................
and Feedback 1A1A2
........
Bessel Filter
.............................................................
Dissipation Limiter ........................................................ .
...................................................
Negative Feedback
Variable Feedback
Positive Feedback
Flag and Overload 1A2A2
.................................................
. .......................................................... ..
........................................
Arc Overloads
VSWR Overload
.............................................................
....................................................
DC Overload
..................................................
Dissipation Limiter .............................................. .
Modulator
Screen Overload ....................................... ..
Overload Counter ........................................................ ..
Remote PA Plate Voltage Metering Amplifier•••••••••·••••
AC Control 1A4
................................................ ..
High/Low Power Control
.........................................
Directional Coupler Board 1A8 ............................................ .
High-Voltage Transformer Protection
..........................
SECTION V. MAINTENANCE
Introduction
Purpose .........................................................
..........................................................
Station Records .
............................................... .
888-2109-010
WARNING: Disconnect primary power prior to servicing.
4-2
4-2
4-4
4-4
4-4
4-4
4-4
4-4
4-5
4-5
4-5
4-5
4-6
4-7
4-7
4-7
4-8
4-8
4-8
4-11
4-11
4-11
4-11
4-11
4-12
4-12
4-12
4-12
4-13
4-13
4-13
4-13
4-13
4-14
4-14
4-14
4-14
4-15
4-15
4-16
4-16
4-16
5-1
5-1
5-1
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TABLE OF CONTENTS (Continued)
Paragraph
5-7.
5-9.
5-11.
5-14.
5-16.
5-18.
5-20.
5-22.
5-23.
5-24.
5-25.
5-26.
5-27.
5-28.
5-29.
5-30.
5-31.
5-32.
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5-36.
5-50.
5-52.
5-54.
5-68.
5-70.
5-71.
5-72.
5-73.
5-75.
5-77.
5-85.
5-87.
5-89.
5-91.
5-92.
5-93.
5-94.
5-95.
6-1.
6-4.
6-7.
6-8.
6-9.
6-10.
vi
Transmitter Logbook
Maintenance Logbook .........................................
0 ••••••••••••••••••••••••••••••••••••••••
Safety Precautions••••••··••••·••·•••········•••·••···········
Preventive Maintenance··············•·••••············•·······
Blower Filter Cleaning .•.•••••••...•.•...•.••••.............
Blower Cleaning ..•..•..•••.••..•• · ••••......••••••..••.•...••
Maintenance of Components•••••••••••••••••••••••••••••••••••
Transistors .•.....•...................•...................
Capacitors ..••.•..•••.•..•..•••••••.•...•••••..••.•.....••
Fixed Resistors ..........•..........•...•.......•.........
Variable Resistors··•··••···••••••••·····••••·············
Transformers ••••••••••••••••••••••••••••••••••••••••••••••
Fuses ••••••••••••.•••••••••••• •• • • • •• •• • • • •• • •• • • • • ••• •• • •
Meters
••••••••.•••••••••••••••••••••• • •••••••• • •• •• •• •••• •
Relays ••••••••••••••••••••••••••••••••••••••••••••••••••••
Switches ••••••••••••••••••••••••••••••••••••••••••••.•••••
Indicators and Indicator Switches•••······••••··••···•····
Printed-Circuit Boards·········•••••••·····••••·•·••••••·•
Corrective Maintenance•••••·•·•••••••••·······••••••··········
Alignment and Calibration •••••••••••••••••••••••••••••••••••••
Transmitter Alignment·•••·•••·········••·•·•••••·••·········
PA Tune Capacitor 1Cl4 ·•••••••··•········••••••·············
3rd Harmonic Resonator Tuning····••••••·•·····•···•••••·•·••
Setting O~tput Network•••••••••·••······••••••··············
Oscillator, IPA, and RF Driver Alignment··•••••••••·········
Oscillator Alignment •••••••••••••••••••••••• _ ••••••••••••••
IPA Tuning •••••••• • ••••••••••••••••••• · ••••••••••••• , ••••••
RF Driver Check ...........................................
Carrier Frequency Check •••••••••••••••••••••••••••••••••••••
Efficiency Tuning·•···•••••••••••·••·••········••••••••••••·
Overload Checks and Adjustments••••········•••••••••···•·••·
Air Pressure Switch Sensitivity•••••••··········•··•••••••••
Electrical Zero of Plate Voltage Meter•••••••·•••·········•·
Audio Input/PDM Control Feedback Board··•·•·····•••••·•·•·••
Audio Board Alignment ··•···•·•·•·•••••••••••••·······•••·•
Audio Board Adjustment·••·•••••·•••••········•·•••••••••
Bessel Filter Adjustment••••••••••·•···········••·••••••
Low-Frequency -3 dB Point Adjustment•••··•···•····••••••
Distortion Minimizatton ••·•••••••••••······••·••••········•·
SECTION VI. TROUBLESHOOTING
General
.......................................................
Technical Assistance··••·•••••••••·•·······••••••····•········
Transmitter Totally Inoperative··•··•••·········••••••••·•··
Transmitter Filament and Low Volts Fails to Stay On •••••••••
High Voltage On Function Inoperative••··••··•·•••·••·······•
High Voltage Immediately Shuts Down When Plate ON
5-1
5-1
5-2
5-2
5-3
5-3
5-3
5-4
5-4
5-4
5-5
5-5
5-5
5-6
5-6
5-6
5-7
5-7
5-8
5-8
5-8
5~11
5-11
5-11
5-24
5-24
5-27
5-29
5-32
5-32
5-32
5-38
5-39
5-40
5-41
5-42
5-43
5-43
5-43
6-1
6-1
6-2
6-2
6-3
Pushbutton Switch Depressed·•··••••••····•·•••••·•••········ 6-3
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TABLE OF CONTENTS (Continued)
Paragraph Page
6-11. No RF Out with Grid Drive, Filaments, and
6-12.
6-13.
6-14.
6-15.
6-17.
6-19.
6-21.
7-1.
7-3.
8-1.
A-1.
HV Supply Normal ...................................... ., •••••••
Poor or No Modulation Capability•••··•·····•·•······•····•··
Poor Performance ••.....•.•...•.••....•...••..•.•..••.•...•••
Overload Shutdowns••••••·•·• .. ·····•••·•····••••··········•··
Modulation Enhancer Malfunction·••••••······••·•·········•··
RF Oscillator Module 1A2Al Malfunction•••··••·•••···········
PDM Module lAlAl Malfunction .... •••••••••••••••••••••••••••••
RF Driver 1A2A3 Malfunction
.................................
SECTION VII. PARTS LIST
6-7
6-7
6-7
6-9
6-10
6-10
6-10
6-10
Introduction ...................................................... 7-1
Replaceable Parts Service•••••••·••••••••••••••••••••••••••••• 7-1
SECTION VIII,
DIAGRAMS
Introduction
..................................................
8-1
APPENDIX A.
DATA
Introduction .•.....•.•.•.•....•.•......•.••••..•...••........•. ·, A-2
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Table
1-1.
1-2.
3-1.
3-2.
3-3.
3-4.
3-5.
3-6.
3-7.
3-8.
3-9.
5-1.
6-1.
6-2.
6-3.
6-4.
7-1.
7-2.
7-3.
7-4.
7-5.
7-6.
7-7.
7-8.
7-9.
7-10.
7-11.
7-12.
7-13.
7-14.
7-15.
7-16.
7-17.
7-18.
7-19.
7-20.
7-21.
7-22.
7-23.
7-24.
viii
LIST OF TABLES
Electrical Characteristics······•··•·•·····•••··········•·····••
Mechanical/Environmental Characteristics••••••••••••••••••••••••
External Meter and Control Panels 1A7 and 1A9, Controls
and Indicators ......................•.•.........................
Meter Panel 1A7 Controls··••·••••·•······•·····•·•••••··········
Meter Panel 1A9 and Directional Coupler 1A8 Controls ••••••••••••
Carrier Tuning Controls and HV Protection Controls and
Indicators ..............................•.......................
AC Power Panel 1A4 Controls and Indicators••••••·····•·••··•···•
Isolated Plate 1A3, Modulation Enhancer 1A1A4, and Fine
Power Adjust, Controls and Indicators•••••••••••••••••••••••••••
PDM Chassis lAl and RF Driver and Overload 1A2, Controls
and Indicators .••..•..•...................••••..•....•..•••...•.
PDM Chassis lAl, Controls and Indicators •••••••••••••••••••.••••
RF Driver and Overload 1A2, Controls and Indicators•••••••••••••
PA Tune Capacitor 1Cl4 Values••·•······••·········•·•···········
Modulation Enhancer 1A1A4 Troubleshooting••·······••••··········
RF Oscillator Module 1A2Al Troubleshooting ••••••••••••••••••••·•
PDM Module lAlAl Troubleshooting••••••••••••••••••••••••••••••••
RF Driver 1A2A3 Troubleshooting····•·•·······••·········••••••••
Replaceable Parts List Index••••••••••••••••••••••••••••••••••••
Xmtr MWSB SkW •••••••••••••••••••••••••••••••••••••••••••••••••••
Mlv5B (Basic) Xmtr •••••••••••••••••••••••••••••••••••••••••••••••
PDM-Chassis-lAl ................................................. .
PDS PC Board ••••••••••••••••••••••••••••••••••••••••••••••••••••
PC Bd Xfmrless and Input••••••••••••••••••••••••• .. ••• .. ••••••• .. ••
Audio Driver .................................................... .
PC Assy :t1El •••••••••••••••••••••••••••••••••••••••••••.•••••••••
RF and Overload···············•••••···•····•••·•·•········•·••••
Oscillator ...................................................... .
RF Driver, 1A2A3
................................................
RF Driver Module·······••••·•••••·····••••·····•··•••········•·•
Flag/Overload PC••••••••••••••••••••••••••••••••••••••••••••••••
PA Grid, Isa Plate ................................................. .
AC Power Panel, 1A4 ................................. .- ••••••••••••••
Relay Overload Board ............................................
Power Supply, 1A.5 .................................... • ........... .
Left Meter Panel 1A7 •••••••••••• .... •••••••••• .. •·•••••••••••••••••
Directional Coupler·•·••••········•·•••·····••·••·•····•••·•··•·
Rt Mrt Panel ...................................................... .
HV Rectifier .................................................... .
Mod Ser PS/Mod Mon••••••••••••••••·•••••••••••••••••••••••••••••
Meter Multiplier•···••••••·••••·······•·····••••·•·······•••·•··
Pwb, HV Protection MW5/10 ...... •••••••••·••••••••••••••••••••••••
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Page (
1-8
1-9
3-3
3-6
3-8
3-10
3-12
3-15
3-18
3-20
3-23
5-12
6-11
6-12
6-15
6-16 •
(
7-2
7-3
7-4
7-7
7-8
7-9
7-12
7-13
7-14
7-15
7-17
7-18
7-19
7-21
7-22
7-23
7-24
7-25
7-26
7-27
7-28
7-29
7-30
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Figure
1-1.
1-2.
1-3.
1-4.
2-1.
2-2.
2-2.
2-2.
2-2.
2-2.
2-2.
2-3.
2-4.
2-4.
2-5.
2-6.
2-7.
2-8.
3-1.
3-2.
3-3.
3-4.
3-5.
3-6.
3-7.
3-8.
3-9.
4-1.
. 4-2.
4-3.
5-1.
5-2.
5-3.
5-4.
5-5.
5-6.
5-7.
5-8.
5-9.
LIST OF ILLUSTRATIONS
MW-5B AM BROADCAST TRANSMITTER••••••••••••••••••••••••••••••••••
MW-5B AM BROADCAST TRANSMITTER, Front View••••••••••••••••••••·•
MW-5B AM BROADCAST TRANSMITTER, Rear View•••••••••••••••••••••••
MW-5B AM BROADCAST TRANSMITTER, Simplified Block Diagram••••••••
Transmitter Outline Drawing••••••·••·····•••···••···············
Transmitter Component Locations (Sheet 1 of 6) ••••••••••••••••••
Transmitter Component Locations (Sheet 2 of 6) ••••••••••••••••••
Transmitter Component Locations (Sheet 3 of 6) ••••••••••••••••••
Transmitter Component Locations (Sheet 4 of 6) ••••••••••••••••••
Transmitter Component Locations (Sheet 5 of 6) ••••••••••••••••••
Transmitter Component Locations (Sheet 6 of 6) ••••••••••••••••••
Transmitter Interconnection Diagram••••·····•••·•···········•·••
HV Transformer Connections, Wiring Diagram (Sheet 1 of 2) •••••••
HV Transformer Connections, Wiring Diagram (Sheet 2 of 2) •••••••
Transmitter Connection Locations ···•••••······•••···········••·•
Blower Belt Tension Adjustment
• ♦ ♦ ♦ ••••••••• ♦ ••••••••••••••••••••
Typical Multimeter Indications••••••••••••••••••••••••••••••••••
Power Amplifier Waveform•••••••••••••••••••••••••••••••••·••••••
External Meter and Control Panels 1A7 and 1A9, Controls and
Indicators ...................................................... .
Meter Panel 1A7 Controls••••••••••••••••••••••••••••••••••••••••
Meter Panel 1A9 and Directional Coupler 1A8 Controls••••••••••••
Carrier Tuning Controls and HV Protection Controls and
Indicators ••••••••••.•••••••••••••••••••• • ••••••••••• • • • ••••••••
AC Power Panel 1A4 Controls and Indicators••••••••••••••••••••••
Isolated Plate 1A3, Modulation Enhancer 1AlA4, and Fine
Power Adjust Controls and Indicators··········••···••···········
PDM Chassis lAl and RF Driver and Overload 1A2
Controls and Indicators••••••••••••·••·····••·••····•···•··••···
PDM Chassis lAl Controls and Indicators··•······•·•······••··••·
RF Driver and Overload 1A2 Controls and Indicators ••••••••••••••
MW-5B AM BROADCAST TRANSMITTER Overall Block
Pulse Duration Modulator, Simplified Diagram .....................
PDM Waveforms "' •••••••••••••••• "'. "' •••••••••• "'."' ••••••••••••••••••
Set-Up for 1L12 Test••••••••••••••••••••••••••••••••••••••••••••
Set-Up for 1L9 Test •••• ~ ....................................... "'.
Setting 3rd Harmonic Resonator
....................................
Set Up for Output Network Test ••o•••••••••••••••••••••••••••••••
Phase Shift Test ••••••• "' •• " .................... " •••••••••••••••••
Ratio of Load Voltage to Plate Voltage Test••••"'••••••••••••••••
Rough Tune-Up Test Set-Up"'''''"''•"••••••••••••••••••••••••••••••
Adjustment of Grid Efficiency Capacitor 1A3C2 ········•····••••··
Correct Power Amplifier Waveform Requirements•·•••••••·•••••••••
888-2109-010
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1-2
1-4
1-5
1-6
2-3
2-6
2-7
2-8
2-9
2-10
2-11
2-13
2-15
2-16
2-17
2-20
2-25
2-28
3-2
3-5
3-7
3-9
3-11
3-14
3-17
3-19
3-21
4-3
4-8
4-9
5-10
5-11
5-13
5-15
5-16
5-18
5-20
5-25
5-33
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Figure
8-1.
8-2.
8-3.
8-4.
8-4.
8-5.
8-6.
8-7.
8-8.
8-8.
8-8.
8-8.
8-8.
8-8.
8-8.
8-8.
8-8.
8-9.
8-9.
8-10.
8-10.
8-11.
8-12.
X
LIST OF ILLUSTRATIONS (Continued)
PAGE
RF and Overload Assembly 1A2, Schematic·····••·•·············••· 8-3
MW-SB AM BROADCAST TRANSMITTER, Overall Schematic••••••••••••••• 8-5
Modulation Enhancer 1AlA4, Schematic·••••·•····················· 8-7
PDM and Audio Driver lAl, Schematic (Sheet 1) ••••••••••••••••••• 8-9
PDM and Audio Driver lAl, Schematic (Sheet 2) ••••••••••••••••••• 8-11
MW-SB Transmitter Frequency Determining Components·····•··•·•••• 8-13
MW-SB Transmitter Control Circuits, Schematic••····••••·•••··••· 8-15
High Voltage Protection Circuity··•••••·····••••··••·••·•••••··· 8-17
Wire Running List (Sheet 1 of 9) ········•••·······••··•••••••••· 8-19
Wire Running List (Sheet 2 of 9) •···········••·•··············•• 8-21
Wire Running List (Sheet 3 of 9) ·······•••·····••··•·••••··•···· 8-23
Wire Running List (Sheet 4 of 9) ··•·•••······•·••••••••·••••••·· 8-25
Wire Running List (Sheet 5 of 9) •·······••·•···········•·•······ 8-27
Wire Running List (Sheet 6 of 9) ·•·••·•·•······••••••···•••••••• 8-29
Wire Running List (Sheet 7 of 9) •·•·······•·••·······•··•······· 8-31
Wire Running List (Sheet 8 of 9) •••••••••••••••••••••••••••••••• 8-33
Wire Running List (Sheet 9 of 9) ··••••••···•·••••••···•··•··•••· 8-35
Wire Running List, PDM and Audio (Sheet 1 of 2) ••••••••••••••••• 8-37
Wire Running
List, PDM and Audio ( Sheet 2 of 2) ................. 8-39
Wire Running
List, Oscillator and RF Driver Cable
( Sheet 1 of 2) • • •• • •• • • •• • • . •• •• • • • • • • • • • • • • • •• • •• • • •• • • • • •• • • • • 8-41
Wire Running List, Oscillator and RF Driver Cable
( Sheet 2 of 2) •••••••••••••••••••••••••••••••••••••••••••••••••• 8-43
Wire Running List, Low Voltage and Modulator Bias••••••••••••••• 8-45
Wire Running List, lAll ••••••••••••••••••••••••••••••••••••••••• 8-47
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1-1. INTRODUCTION
SECTION I
GENERAL DESCRIPTION
1-2. This Technical Manual contains all information necessary to install,
operate, maintain, and service the HARRIS MW-SB AM BROADCAST TRANSMITTER
(refer to figure 1-1). The various sections in this Technical Manual
provide the following types of information.
a. SECTION I GENERAL DESCRIPTION, provides a description of the
equipment, identifies the major components, lists operating pa-
rameters and specifications, and describes other pertinent fea-
tures of the equipment.
b. SECTION II INSTALLATION, provides information relative to incom-
ing inspection, power requirements, input/output connections, and
component mounting
instructions.
c. SECTION III OPERATION, provides identification and functions of
panel or component mounted controls and indicators, along;c with
information necessary to setup and operate the transmitter.
d. SECTION IV PRINCIPLES OF OPERATION, provides descriptions of
functional circuits within the transmitter, beginning with a
general overall block diagram discussion and proceeding through
detailed printed-circuit board discussion.
e. SECTION V MAINTENANCE, provides information pertaining to pre-
ventive and corrective maintenance, along with applicable perfor-
mance schedules.
f. SECTION VI TROUBLESHOOTING, provides fault location guidance and
troubleshooting procedures along with instructions for equipment
servicing.
g. SECTION VII PARTS LIST, provides information for ordering re-
placement electrical components and assemblies together with
selected mechanical parts.
h. SECTION VIII DIAGRAMS, provides block, logic, and schematic dia-
grams and other drawings necessary for maintaining the trans-
mitter.
i. SECTION IX APPENDIX, provides manufacturers data.
1-3, PHYSICAL DESCRIPTION
1-4 • The HARRIS MW-SB AM BROADCAST
and is completely self-contained in
transmitter components, except the
TRANSMITTER has no external components
one
equipment cabinet. Access to all
transmitter controls and meter panels,
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Figure 1-1. MW-SB AM BROADCAST TRANSMITTER
(
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are achieved through the easily removed front and rear cabinet doors
(figures 1-2 and 1-3), The swing-up transmitter control and meter panels
are located at eye level on the front of the transmitter.
1-5, Opening the front left-hand door exposes the PDM Chassis, RF Driver
Chassis, and the remote power control, which are mounted on swing-down
panels on the internal control panel. The internal control panel also
accommodates the vernier control used to regulate output power,
1-6. Opening the front right-hand door exposes the protective circuit
breaker controls, and remote/local control switch. The protective circuit
breakers, LOCAL/REMOTE CONTROL, FILAMENT HOURS meter, FILAMENT VOLTAGE
adjustment, DC OVERLOAD adjustment, and MOD SCR VOLTAGE HI POWER and LOW
POWER adjustments are all located on the lower right-hand panel.
1-7. Fault indicating devices for the Power Amplifier Driver modules are
located in the RF Driver enclosure area.
1-8. The High-Voltage Transformer protection panel is located in the upper
right-hand corner of the lower left-hand panel. The panel has access holes
for test points, GAIN ADJUST potentiometer, and the HIGH VOLTAGE. .. FAULT
indicator (LED).
1-9. Filtered cooling air for the transmitter is provided
filter located at the bottom rear of the equipment cabinet.
may be removed for cleaning during transmitter operation.
1-10. FUNCTIONAL DESCRIPTION
by a blower and
The
air filter
1-11. The basic functional circuits in. the HARRIS .MW-SB AM BROADCAST TRANS-
MITTER consists of an Audio Section, RF Section, Control Section, and a
Power
Supply Section (figure 1-4).
1-12 The Audio Section includes a Modulation Enhancer, Audio Input Circuit
(located on the PDM Control and Feedback Board), PDM Board Audio Driver,
Modulator Tube, and the 75 kHz Filter. The PDM frequency is nominally 75
kHz, but may actually be several kHz above or below this value.
1-13, The RF Section includes a Crystal Oscillator, Intermediate Power
Amplifier Module, four RF Driver Modules, and the PA Tube (3CX2500F3).
1-14. The Control Section includes power, personnel safety, and transmitter
control circuits.
1-15. The Power Supply Section consists of a High-Voltage Power Supply, a
60-volt supply, a 120-volt supply, and a 30-volt supply.
1-16. The audio input to the transmitter is applied through the Modulation
Enhancer, through a pad and balanced-to-unbalanced transformer, and the audio
then pulse-width modulates a 75 kHz signal which is again amplified to drive
the grid of the Modulator Tube.
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Figure 1-2. MW-SB AM BROADCAST TRANSMITTER, Front View
(
1-4 888-2109-010
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L
j
d
I
4.
I
l
Figure 1-3.
MW-SB AM BROADCAST TRANSMITTER, Rear View
888-2109-010
1-5
WARNING: Disconnect primary power prior to servicing.