Harris 994 8047 001 User manual

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TECHNICAL MANUAL
FM- 2.5K FM TRANSMITTER
994 8047 001
994 8047 004
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M Fi.o.F1Fas
T.M. No. 888-1759-004
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0 Copyright HARRIS CORPORATION
1985 All Rights Reserved
Printed: March 4, 1985

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MANUAL REVISION HISTORY
FM- 2.5K FM TRANSMITTER
888-1759-xxx
REV. # DATE ECN PAGES AFFECTED
002 06/84 27895 Replaced all pages.
Added Manual Revision History page.
003 11/06/84 29204 Replaced the following pages:
Title Page, Manual Revision History Page
vi, 7-1/7-2, 7-11/7-12
004 03/04/85 29376 Replaced the following pages:
Title Page, Manual Revision History Page
1-5, 2-3, 4-1, 6-3, 6-4, 7-13/7-14
888-1759-004

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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.

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
IF PULSE ABSENT.
BEGIN ARTIFICIAL
CIRCULATION
BREATHING
IF NOT BREATHING.
BEGIN ARTIFICIAL BREATHING
TILT HEAD
PINCH 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
APPROX. RATE ONE RESCUER
OF COMPRESSIONS 15 COMPRESSIONS
-- 80 PER MINUTE 1.2 QUICK BREATHS
APPROX. RATE f TWO RESCUERS
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
D. A RECLINING POSITION IS RECOMMENDED
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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)
888-1759-002 iii

TABLE OF CONTENTS
Paragraph Page,
SECTION I. GENERAL DESCRIPTION
1-1. Introduction 1-1
1-3. Related Publications 1-1
1-5. Equipment Purpose 1-1
1-7. Physical Description 1-1
1-10. Functional Description 1-2
1-11. Power Supplies 1-2
1-13. FM Exciter 1-3
1-15. RF Circuits 1-3
1-18. Metering 1-3
1-20. Control Circuits 1-3
1-22. Safety 1-3
1-24. Equipment Characteristics 1-4
1-25. Electrical Characteristics 1-4
1-27. Mechanical/Environmental Characteristics 1-4
SECTION II. INSTALLATION
2-1. Introduction 2-1
2-3. Unpacking 2-1
2-5. Returns and Exchanges 2-1
2-7. Installation 2-1
2-9. Cooling Air Requirements 2-1
2-12. Transmitter Placement 2-2
2-16. Component Installation 2-2
2-30. Wiring Connections 2-3
2-37. Initial Checkout 2-4
2-43. Connections to Remote Controls 2-a5
SECTION III. OPERATION
3-1. Introduction 3-1
3-3. Adjustment 3-1
3-27. Operation at Output Power Below 2500 Watts 3-3
SECTION IV. CIRCUIT DESCRIPTION
4-1. Introduction 4-1
4-4. Power Amplifier ( PA) 4-1
4-9. Intermediate Power Amplifier ( IPA) 4-2
4-14. FM Exciter 4-2
4-15. Power Supply 4-2
4-18. Control Circuits 4-2
4-20. RF Filtering 4-3
4-23. Metering 4-3
SECTION V. MAINTENANCE
5-1. Introduction 5-1
5-3. Purpose 5-1
5-5. Station Records 5-1
5-7. Transmitter Logbook 5-1
iv 888-1759-002
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WARNING: Disconnect primary power prior to servicing.

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TABLE OF CONTENTS ( Continued)
Paragraph Page
5-9. Maintenance Logbook 5-1
5-11. Safety Precautions 5-2
5-14. Preventive Maintenance 5-2
5-16. Filter Cleaning 5-3
5-18. Blower Maintenance 5-4
5-22. Maintenance of Components 5-4
5-24. Semiconductors 5-4
5-25. Capacitors 5-4
5-26. Tubes 5-5
5-30. IPA Grid Circuit 5-5
5-32. Fixed Resistors 5-5
5-33. Variable Resistors 5-6
5-34. Transformers 5-6
5-35. Fuses 5-6
5-37. Relays 5-7
5-38. Switches 5-7
5-39. Indicators and Indicator Switches 5-8
5-40. Printed Circuit Boards 5-8
5-41. Corrective Maintenance 5-9
5-43. Troubleshooting 5-9
5-49. Technical Assistance 5-9
SECTION VI. PARTS LIST
6-1. Introduction 6-1
6-3. Replaceable Parts Service 6-1
888-17597002 v
WARNING: Disconnect primary power prior to servicing.

LIST OF TABLES
Table Page
1-1. Electrical Characteristics 1-5
1-2. Mechanical/Environmental Characteristics 1-6
5-1. Air Filters 5-3
6-1. Replaceable Parts List Index 6-2
6-2. FM - 2.5K 2.5KW FM XMTR 6-3
6-3. FM - 2.5K 2.5KW FM XMTR 6-4
6-4. Xmtr Basic FM2.5H3 6-5
6-5. Scrn Motor Assy 6-6
6-6. Sw. Pnl. Assy 6-7
6-7. Meter Pnl Assy 6-8
6-8. Frnt. Pnl Assy 6-9
6-9. PA Enclosure Assy 6-10
6-10. Shelf Assy 6-11
6-11. IPA Assy 6-12
6-12. Pnl Assy 6-13
6-13. Meter Multiplier 6-14
LIST OF ILLUSTRATIONS
!Lem_ Page
7-1. Block Diagram, FM- 2.5K 7-3
7-2. Coarse Plate Tuning Chart, FM- 2.5K 7-5
7-3. Installation Layout, FM- 2.5K 7-7
7-4. 2nd Harmonic Filter, FM Transmitters 7-9
7-5. PA Efficiency Curve, FM-2.5H3/FM-2.5K 7-11
7-6. Overall Schematic, FM- 2.5K 7-13
vi 888-1759-003
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WARNING: Disconnect primary power prior to servicing.

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SECTION I
GENERAL DESCRIPTION
1-1. INTRODUCTION
1-2. This techn:cal manual contains information necessary to install,
operate, maintain, and service the HARRIS FM- 2.5K FM BROADCAST TRANSMITTER.
1-3. RELATED PUBLICATIONS
1-4. The following publications provide information related to associated
equipment.
PUBLICATION NUMBER EQUIPMENT IDENTIFICATION
888 1742 001 MS- 15 FM EXCITER
OR OR
988 1957 001 MX- 15 FM EXCITER
1-5. EQUIPMENT PURPOSE
1-6. The HARRIS FM- 2.5K FM TRANSMITTER is a 2500- watt FM Transmitter
designed for continuous broadcast operation. The transmitter uses either
the HARRIS MS- 15 FM Exciter or the HARRIS MX- 15 FM Exciter and a two- tube
amplifier to provide reliable and efficient operation in the 87.5 to 108 MHz
commercial FM Broadcast Band. The FM Exciter plug-in modules provide
monaural or stereophonic operation with up to two SCA channels. Plug-in
module provisions for operation of a future quadraphonic transmission system
are also provided in the FM Exciter.
1-7. PHYSICAL DESCRIPTION
1-8. The entire unit, including the FM Exciter, IPA, PA, associated power
supplies, metering, Low- Pass Filter, and control circuits are contained in
one cabinet. All required metering is provided by four meters located on a
panel along the top edge of the transmitter cabinet and a filament voltage
meter located behind the front door. The front door opens to expose the FM
Exciter and all required operating controls necessary for normal operation
in full view of all front panel indicators. Both the front and rear doors
may be removed for better access. The PA and IPA area is accessed through
an interlocked rear cover and the control and power supply area is accessed
through the rear door.
1-9. The following controls are located on the front panels.
a. Filament ON
b. Filament OFF
c. Plate ON
888-1759-002 1-1
WARNING: Disconnect primary power prior to servicing.

d. Plate OFF
e. Power/VSWR Selector
f. Power Calibrate
g. VSWR Calibrate
h. Multimeter Selector
j. Power Raise/Lower
j. PA Bias Adjust
k. PA Plate Tuning
I. PA Output Loading
m. PA Grid Tuning
n. PA/IPA Filament Voltage
o. PA Filament Voltage
p. IPA Filament Voltage
q. IPA Plate Tuning
r. IPA Output Loading
s. Remote/Local
t. Potentiometers ( 4) for adjustment of PA Plate Current Remote
Reading, Recycle, PA Overload, and PA Plate Voltage Remote Reading
1-10. FUNCTIONAL DESCRIPTION
1-11. POWER SUPPLIES
1-12. Three power supplies are used for the following functions:
a. PA Bias Voltage
b. ( 1) IPA Plate and Screen Grid Voltage
(2) PA Screen Grid Voltage
c. PA Plate Voltage
1-2 888-1759-002
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1-13. FM EXCITER
1-14. The FM Exciter produces a frequency- modulated output continuously
variable from three to 15 watts into a 50- ohm load for any channel assign-
ment within the 87.5 to 108 MHz commercial FM Broadcast Band. Servicing is
simplified as the FM Exciter is modular in concept and discrete functions
are complete within individual plug-in modules. The metering panel contains
a true peak- reading audio meter and a multimeter which monitors important
rf, audio, and control voltages. Light emitting diode ( LED) status indica-
tors monitor critical functions on each plug-in module. Operational modes
include up to two SCA channels, monophonic, stereophonic, and provisions for
future quadraphonic transmission.
1-15. RF CIRCUITS
1-16. The transmitter RF Chain consists of two tubes. A 4X150A tetrode IPA
amplifies the FM Exciter output, as required, to drive the single- ended,
Class C operated, 5CX1500A PA tube stage to output 2500 watts of RF Power.
Fixed bias ensures dependable PA stage operation. Grid leak bias, protected
by the control circuitry and neutralization, ensures stable IPA stage
operation. Forced air cooling and an air switch arrangement ensures cool
operation and long tube life.
1-17. RF Output Power is inductively coupled from the plate lines. The
amplifier loading is changed by a variable output loading control. The rf
output to the antenna is fed through a Low- Pass Filter arrangement ( internal
to the PA cavity), a 2nd Harmonic Stub Filter, and a Directional Coupler.
1-18. METERING
1-19. Two meters and an arrangement of light emitting diodes ( LED) provide
status indications of FM Exciter operation. Five meters monitor transmitter
parameters relative to the IPA and PA stages.
1-20. CONTROL CIRCUITS
1-21. The FM- 2.5K Transmitter control circuits contains an automatic
recycle feature which turns off high voltage momentarily if a fault occurs,
and then automatically restores the transmitter to operation. If the fault
is still present, or another overload occurs, another interruption cycle is
accomplished. Up to three or four recycles within a preset time interval
may be attempted before the transmitter shuts down and must be manually
reset.
1-22. SAFETY
1-23. If the cabinet back door is opened during operation, the high- voltage
and PA screen power supplies are discharged and the ac primary voltage to
both power supplies is opened. The power supplies must be manually reener-
gized after this sequence occurs. USE OF THE SAFETY HOOK TO DISCHARGE ALL
SUPPLIES IS RFcOMMENDED BEFORE SERVICING.
888-1759-002 1-3
WARNING: Disconnect primary power prior to servicing.

1-24. EQUIPMENT CHARACTERISTICS
1-25. ELECTRICAL CHARACTERISTICS
1-26. Table 1-1 lists electrical operating characteristics and parameters
of the FM- 2.5K Transmitter.
1-27. MECHANICAL/ENVIRONMENTAL CHARACTERISTICS
1-28. Table 1-2 lists physical and environmental characteristics of the
FM- 2.5K Transmitter.
NOTE
Specifications subject to change with-
out notice.
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1-4 888-1759-002
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Table 1-1. Electrical Characteristics
FUNCTION
CHARACTERISTIC
PRIMARY POWER REQUIREMENTS
Transmitter
Exciter
POWER CONSUMPTION
(Typical for 2.5 kW RF Output)
POWER FACTOR
POWER LINE VARIATION ( Slow)
RF POWER OUTPUT
RF OUTPUT IMPEDANCE
RF FREQUENCY RANGE
MAXIMUM VSWR
RF OUTPUT TERMINATION
RF HARMONIC SUPPRESSION
TUBES USED
AM Noise
FM Noise
Refer to FM Exciter specifications
for additional characteristics.
197/250V, 60 or 50 Hz, single phase
115 Vac, 60 or 50 Hz, single phase
4800 watts ( approximate) transmitter
150 watts for FM Exciter
90%
+5%
1.0 kW to 2.5 kW ( FCC Type Accepted)
50 ohms
87.5 to 108 MHz
1.7 to 1
1-5/8 inch ( 4.13 cm) EIA flange
Meets all FCC requirements.
1-4X150A ( IPA)
1-5CX1500B ( PA)
55 dB
80 dB ( Wideband operation)
888-1759-004
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WARNING: Disconnect primary power prior to servicing.

Table 1-2. Mechanical/Environmental Characteristics
FUNCTION
CHARACTERISTIC
Weight ( Unpacked)
(Packed)
Cubage ( Packed)
Size
Front Door Swing
Operating Temperature Range
Maximum Altitude
Maximum Humidity
COOLING AIR REQUIREMENTS
AIR INLET SIZES
Lower Front Panel:
Lower Back Door:
Blower:
AIR OUTLET SIZE
Refer to FM Exciter specifications
for additional characteristics.
Domestic 730 pounds ( 331.13 kg)
Export 740 pounds ( 335.66 kg)
Domestic 1051 pounds ( 476.73 kg) in
5 pieces
Export 1165 pounds(476.73 kg) in 4
pieces
Domestic 94.6 ft 3 ( 2.68 m3)
Export 103.5 ft 3 ( 2.93 m3)
Width, 29 inches ( 73.7 cm)
Depth, 33 inches ( 84 cm)
Height, 78 inches ( 198 cm)
29 inches ( 73.7 cm)
0° C to 45° C. Usable to
-20° C with slight reduction in
operating parameters.
7500 feet ( 2250 meters) above sea
level
95% noncondensing
140 CFM ( 3.96 M3 /Min) nominal
1.8 inches ( 4.57 cm) water gauge
20.875- inch X 7- inch X 1 inch
(50.02 cm X 17.78 cm X 2.54 cm)
24- inch X 24- inch X 1 inch
(60.96 cm X 60.96 cm X 2.54 cm)
8.5- inch X 8.5- inch X 1 inch
(21.59 cm X 21.59 cm X 2.54 cm)
18- inch ( 45.7cm) X 14- inch ( 35.6cm)
1-6 888-1759-002
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SECTION II
INSTALLATION
2-1. INTRODUCTION
2-2. This section contains information for installing the HARRIS FM- 2.5K
FM BROADCAST TRANSMITTER and performing pre- operational checks. Some
components were removed from the traqsmitter after final test for shipment.
These components will be identified with appropriate instructions for
reinstallation and wiring.
2-3. UNPACKING
2-4. Carefully unpack the FM- 2.5K Transmitter and perform a visual inspec-
tion to determine that no apparent damage was incurred during shipment.
Retain the shipping materials until it has been determined that the unit is
not damaged. 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 the carrier and HARRIS CORPORATION,
Broadcast Transmission Division.
2-5. RETURNS AND EXCHANGES
2-6. Damaged or undamaged equipment should not be returned unless written
approval and a Return Authorization is received from HARRIS CORPORATION,
Broadcast Transmission Division. Special shipping instructions and coding
will be provided to assure 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
Transmission Division, specify the Factory Order Number or Invoice Number.
2-7. INSTALLATION
2-8. Prior to installation, this Technical Manual and the appropriate FM
Exciter Technical Manual should be carefully studied to obtain a thorough
understanding of the principles of operation, circuitry, and nomenclature.
This will facilitate proper installation and initial checkout.
2-9. COOLING AIR REQUIREMENTS
2-10. If a means of exhausting hot air from the transmitter enclosure or
transmitter room is used, the duct system must not introduce any back
pressure on the transmitter air exhaust. Allowances must be made for a
minimum air flow of 140 CFM ( 3.96 m3 /minute) to ensure that only a limited
amount of direct heat is dissipated into the transmitter interior. The duct
work must have a cross sectional area equal to the opening at the top of the
transmitter. Sharp right angle bends in the duct system are not permissible.
888-1759-002 2-1
WARNING: Disconnect primary power prior to servicing.

If it is necessary to turn a right angle, a radius- type bend must be used.
The exhaust fan in the duct system must overcome any duct loss and overcome
any wind pressures, if vented to the outside.
2-11. After the transmitter has operated at full output for a number of
hours, the temperature rise inside the transmitter must not exceed a rise of
68°F ( 38°C) above the ambient temperature measured at the blower air in-
take. The ambient air temperature must not rise above 113°F ( 45°C)
under any circumstance.
2-12. TRANSMITTER PLACEMENT
2-13. A certain amount of planning should be accomplished in advance of the
actual placement of the equipment. Holes are provided in the base of the
transmitter for entry of power, audio, and remote control wires. Also,
several knockout holes are provided if other entry positions are desired.
Refer to figure 7-3 Installation Layout.
2-14. Either side of the transmitter may be placed against a wall or other
equipment. Complete accessibility for maintenance and installation is pro-
vided in the FM- 2.5K Transmitter by access from the rear of the transmitter
cabinet.
2-15. Set the FM- 2.5K Transmitter in place on a smooth, level surface near
power and signal cables. The sides of the transmitter may be placed against
a wall or other equipment as complete accessibility for installation and
maintenance is provided by the rear door. The floor must be capable of
supporting a load of approximately 100 pounds per square foot ( 487 kg/m 2 ).
2-16. COMPONENT INSTALLATION
2-17. Tubes, capacitors, connectors, and cables are shipped in separate
cartons. The removal of components varies due to the method and require-
ments of shipment. All removed items will be tagged to permit reinstalla-
tion in the transmitter. Arrange these components in separate groups
according to the section from which they are removed. Parts in the interior
should be installed first. The transmitter rear door and the internal access
panels should be removed and left off until the installation of removed
components and cabinet wiring hook up has been completed.
2-18. Items such as interconnecting wires, cables, shock mounted devices,
and miscellaneous small parts may be taped or tied in for shipment. Remove
all tape, string, and packing material that has been used for this purpose.
2-19. Symbol numbers and descriptions are provided on each removed compo-
nent corresponding to the schematic diagram, parts list, and packing list.
Symbol numbers are also stenciled near the cabinet location of each removed
item. Terminals and wires carry tags with information telling how to recon-
nect each item. Mounting hardware will be found either in small bags,
attached to each removed component, or inserted in the tapped holes where
each component mounts. Reinstall each component in its proper location.
2-2 888-1759-002
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AVOID BUMPING THE TUBES. DUE TO THE
MASS OF LARGE TUBES, BUMPING WILL
INTRODUCE STRESSES WHICH MAY CAUSE
INTERNAL DAMAGE.
2-20. Install time- delay relay K4.
2-21. Remove all the covers from the PA and IPA enclosures.
2-22. Loosen the four captive screws that hold the PA anode and blocking
capacitor assembly to the vertical plate lines. Remove the blocking
assembly from the PA enclosure.
2-23. Carefully lower the 5CX1500B tube into its socket until it rests on
the socket base. Check to see that the tube contacts line up with the
socket fingers and rotate the tube until it hits a stop.
2-24. Install the anode and blocking capacitor assembly over the 5CX1500B
tube anode. Align the four captive screws with the press- in nuts on the
plate lines and tighten securely.
2-25. Position the B+ feed connector on the 5CX1500B tube anode cap and
tighten the holding screw. Dress the B+ wire to the right in a smooth
radius to the tubing.
2-26. Inspect the IPA circuitry. Make certain the 4X150A tube is properly
seated and the anode clamp holds the chimney against the tube socket.
Install the cover on the IPA enclosure. Push the air tube from the PA
enclosure down to the stenciling ( Air Tube) through the grommeted hole in
the IPA cover.
2-27. Install the covers on the PA enclosure.
2-28. Connect the transmission line to transmitter rf output at the
Directional Coupler ( DC1).
2-29. Install the FM Exciter modules that were removed for shipment.
2-30. WIRING CONNECTIONS
WARNING
BEFORE PROCEEDING, ENSURE THAT STATION
PRIMARY POWER IS NOT CONNECTED TO THE
TRANSMITTER.
888-1759-004 2-3
WARNING: Disconnect primary power prior to servicing.

2-31. After the transmitter is physically in place and the components
removed for shipment have been reinstalled, the audio and ac power should be
brought to the transmitter.
2-32. The audio input line enters the base of the transmitter near the wire
channel and connects directly to the FM Exciter terminal board.
2-33. The ac input for the transmitter should come from low reactance,
50/60 Hz, single phase supply with approximately a 5500 VA capacity. A
terminal board is installed on the rear left side of the transmitter base
for ac connections.
2-34. The ac input wiring should be in agreement with local electrical
codes and capable of supplying the transmitter power requirements. An ac
primary power disconnect or means to completely deenergize the transmitter
primary circuit for servicing is strongly recommended. If the program leads
must be routed in close proximity to the ac power input wiring, the program
leads should be separately shielded.
2-35. Connect 115 Vac to terminals 1 and 2 of terminal board TB5. This
terminal board is located in front of the blower mounting.
2-36. A good ground at FM frequencies is mandatory to keep stray rf cur-
rents to a minimum. RF interference usually shows up in one of two ways,
feedback or high noise ( in some cases both). It should be pointed out that
even a small amount of unshielded wire makes a very efficient antenna for FM
frequencies. If rf from the cabinet field is transferred to the audio
equipment, it can be rectified and may show up as noise or feedback. A
single common ground point from the transmitter base to a good grounding
system, such as a water pipe or actual earth ground is recommended. A
grounding stud is located adjacent to the AC Input terminal board.
2-37. INITIAL CHECKOUT
WARNING 1
DISCONNECT AND LOCK OUT STATION PRIMARY
POWER TO THE TRANSMITTER. USE THE
GROUNDING HOOK AND DISSIPATE ANY
RESIDUAL POTENTIAL FROM ALL COMPONENTS
BEFORE TOUCHING THEM.
2-38. Each transmitter is thoroughly checked out during factory final test
but adjustment is normally required during installation due to shipping,
variations in primary power, antenna systems, or transmission line
differences. A 20k ohm/volt multimeter ( Simpson 260 or equivalent) is
required for the checkout.
2-39. Before proceeding with the initial FM- 2.5K Transmitter testing, ensure
that the FM Exciter is completely installed, all parts are back in position
2-4 888-1759-002
WARNING: Disconnect primary power prior to servicing.
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