Continental Electronics 316F User manual

TYPE 316F/315F
Am u BROADCAST TRANSMITTER
WITH SOLID STATE EXCITER
1
INSTRUCTION MANUAL
107600-4
Ciretlipt.e.it_LaL
S. ExickrvEszt EitLNICP. CPA LL AS. TEXAS 75227'
ET1-5-24

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TYPE 316F/315F
a BROADCAST TRANSMITTER
WITH SOLID STATE EXCITER
II
MANUAL
107600-4
CIT7tILWt_t_al. el-e-C-LILCr7tiCwel_ rvi. co.
4 212 S. BUCK IVER lEtlAell). 11)A LL AS. TEXAS 752.27'
ET1-5-24

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CHANGE NOTICE
CHANGE NO. 10
TO
TYPE 316F/315F
AM BROADCAST TRANSMITTER
INSTRUCTION MANUAL
This Change No. 10 is effective for all 316F/315F Transmitters.
Remove the old page and insert the new page. Insert this Change
Notice just after the Title Page.
NEW PAGE
OLD PAGE
2-1/2-2 ClO/C5
2-1/2-2 C5/C5
11 July 1984
Continental Electronics Mfg. Co.
4212 South Buckner Blvd.
Dallas, Texas 75227-4299

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316F
RECORD OF CHANGES
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CHANGE NO. EFFECTIVE DATE EFFICTIVITY
1, 2 & 3 1 June 1974 S/N 2 and ABOVE
4 1 July 1975 S/N 2 and ABOVE
5 1 October 1980 S/N 188 and ABOVE
6 28 August 1981 S/N 201, 204, 212
and ABOVE
7 1 October 1981 S/N 212 and ABOVE
8 3 November 1981 S/N 212 and ABOVE
9 3 February 1982 S/N 232 and ABOVE
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TYPE 316F/315F
TABLE OF CONTENTS
• PARAGRAPH PAGE
SECTION 1 - GENERAL INFORMATION
1-1. Introduction 1-1
1-2. Optional Equipment and Circuitry 1-1
1-3. General Description 1-2
1-4. Solid- State Exciter 1-5
1-5. Power Amplifier 1-5
1-6. Harmonic Filter 1-6
1-7. Forced Air Cooling 1-7
1-8. Power Supplies 1-7
1-9. Technical Characteristics 1-8
1-10. Tube and Semiconductor Complement 1-8
SECTION 2 - INSTALLATION
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2-1. Introduction 2-1
2-2. General 2-1
2-3. Customer Furnished Equipment Required 2-1
2-4. Unpacking and Inspection 2-2
2-5. Assembly Procedure 2-2
2-6. Transmitter Cooling and Air Exhaust 2-6
2-7. External Connections to 316F/315F 2-6
2-8. Pre- Operational Checkout 2-7
2-9. Initial Adjustments 2-11
2-10. Alignment/Calibration Procedures 2-11
SECTION 3 - OPERATION
3-1. Introduction 3-1
3-2. Preparation for Operation 3-1
3-3. Turn- On Procedure 3-1
3-4. Turn- Off Procedure 3-2
3-5. Emergency Turn- Off Procedure 3-2
3-6. Operating Controls and Indicators 3-3
3-7. Operating Voltages and Currents 3-16
Change 5
iii

TYPE 316F/315F
TABLE OF CONTENTS - Cont.
PARAGRAPH PAGE
SECTION 4 - THEORY OF OPERATION
4-1. Introduction 4-1
4-2. Solid- State Exciter 4-1
4-3. RF Section 4-1
4-4. Crystal Oscillator 4-2
4-5. 1st Buffer Amplifier 4-2
4-6. 2nd Buffer Amplifier 4-4
4-7. 3rd Buffer Amplifier 4-4
4-8. Frequency Monitor 4-4
4-9. RF Driver 4-5
4-10. Modulated Power Amplifier 4-5
4-11. Audio Section 4-6
4-12. Audio Input Amplifier, A6 4-6
4-13. 2nd Audio Amplifier and Modulator 4-7
4-14. Feedback Rectifier Circuit 4-12
4-15. Magniphase Section 4-12
4-16. Cooling Air 4-13
4-17. High- Efficiency Linear Amplifier 4-14
4-18. General Description 4-14
4-19. Power Amplifier Grid Circuit Description 4-17
4-20. Cathode Degeneration 4-20
4-21. Screen Voltage 4-20
4-22. Power Amplifier Plate Circuit Description 4-21
4-23. Tee Network Description 4-21
4-24. Pi Network Description 4-22
SECTION 5 - MAINTENANCE
5-1. Introduction 5-1
5-2. Preventive Maintenance 5-1
5-3. Control Circuits 5-3
5-4. Control Voltages 5-3
5-5. Transmitter Starting Sequence 5-3
5-6. Overload and Lockout Circuits 5-4
5-7. Component Identification and Locations 5-5
5-8. Alignment/Calibration Procedures 5-21
5-9. RF Driver and Modulated Power Amplifier(RF Output) 5-21
5-10. PA Grid Network - Initial Alignment 5-21
5-11. PA Output Circuit 5-23
5-12. " T" Network Tune Up 5-23
5-13. " PI" Network Tune Up 5-24
5-14. PA Interplate Network - Initial Alignment 5-24.1
5-15. Alignment Charts 5-24.2
iv Change

TYPE 316F/315F
TABLE OF CONTENTS - Cont.
Ile - PARAGRAPH
SECTION 5 - MAINTENANCE - Cont.
PAGE
5-16. Test Points 5-33
5-17. Adjustments of L3 & L6 ( Exciter) 5-36
5-18. Adjustment Controls ( Power Amplifier) 5-38
5-19. Tuning for Minimum Distortion 5-39
5-20. Adjustment of 24 Volt Supply 5-41
5-21. Modulation Monitor Drive 5-42
5-22. Drawings and Schematics 5-43
FIGURE
LIST OF ILLUSTRATIONS
SECTION 1 - GENERAL INFORMATION
1-1. Type 316F/315F AM Broadcast Transmitter, Front View.
1-2. Type 316F/315F AM Broadcast Transmitter, Showing
Major Sections, Doors Open, Front View
1-3. Type 316F/315F AM Broadcast Transmitter, Showing
Major Sections, Doors Open, Rear View
SECTION 2 - INSTALLATION
PAGE
2-1. Transmitter, Overall Front View, Showing Components
Removed for Shipment, Front View
2-2. Transmitter Overall Rear View, Showing Components
Removed for Shipment
SECTION 3 - OPERATION
2-3
2-4
3-1. Manual Tuning Controls, Shown on Upper- Left Panel,
Lower Doors Open, Front View 3-5
3-2. Operating Controls and Metering Panel, Front View. . 3-9
3-3. Solid- State Exciter and Magniphase-Control/Indicators,
Front View 3-13
3-4. Control Section, Showing Circuit Breakers, Front View 3-15
gle 3-5. Peak Clipper Controls 3-21
Change 5

TYPE 316F/315F
LIST OF ILLUSTRATIONS - Cont.
FIGURE PAGE
SECTION 4 - THEORY OF OPERATION
4-1. Solid- State Exciter, Type 316F/315F Transmitter,
Block Diagram 4-3
4-2. Modulator and 2nd Amplifier, Simplified Schematic. . 4-8
4-3. High- Efficiency Linear Power Amplifier, Type 316F/315F
Transmitter, Simplified Diagram 4-15
SECTION 5 - MAINTENANCE
5-1. Transmitter Overall Front View, Showing Major Sections,
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Doors Open 5-6
5-2. PA Grid Networks, Showing Carrier Tube Components
(Left Half) and Peak Tube Components ( Right Half),
Internal Front View 5-7
5-3. Operating Controls and Metering, Hinged Front Panel,
Rear View 5-8
5-4. Solid- State Exciter and Magniphase Panel, Showing
Component Locations, Front View 5-9 Ill,
5-5. Solid- State Exciter and Magniphase Panel, Showing
Component Locations, Rear View 5-10
5-6. + 120 Volt Power Supply, Showing Component Locations,
Front View 5-11
5-7. Control/Remote Compartment, Showing Circuit Breakers
and Component Locations, Front View 5-12
5-7.1 Remote Control and Power Reduction Components
Optional 5-12.1
5-8. Transmitter Overall Rear View, Showing Major
Compartment Areas, Doors Open 5-13
5-9. RF Output Network, Showing Peak Plate and Tee Network
Inductors, Upper Left- Hand Compartment, Rear View. . . 5-14
5-10. RF Output Network, Showing Tee Network Inductors and
Condensers, Viewed from Rear 5-15
5-11. High Voltage Plate Transformer and Bias Supply,
Lower Left- Hand Compartment, Viewed from Rear 5-16
5-12. Power Amplifier Tubes and Manually Operated Tuning
Condensers, Viewed from Rear 5-17
5-13. Power Amplifier Filament Transformers, Rear View . . 5-18
5-14. Cooling Blower for Power Amplifier Tubes, Viewed from
Rear 5-19 11,
5-15. High Voltage Plate and Screen Supply Compartments,
Viewed from Rear 5-20
vi Change 5

TYPE 316F/315F
LIST OF ILLUSTRATIONS - Cont.
• FIGURE PAGE
SECTION 5 - MAINTENANCE - Cont.
5-15.1 Peak Clipper Assembly, Top 5-20.1
5-15.2 Peak Clipper Assembly, Bottom 5-20.2
5-16. Tee Network Coils ( L17 and L18) - Alignment
Chart 5-25
5-17. Tee Network - 2nd Harmonic Trap ( L19 and C54) -
Alignment Chart 5-26
5-18. Pi Network Condensers ( C51 and C52) - Alignment
Chart 5-27
5-19. Pi Network Coil ( L16) - Alignment Chart 5-28
5-20. Carrier Plate Condenser ( C49) - Alignment Chart 5-29
5-21. Interplate Coil ( L14 and L13) - Alignment Chart 5-30
5-22. Grid Tank Circuits - Alignment Chart 5-31
5-23. Peak Grid Condenser ( C43) - Alignment Chart. . . 5-32
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LIST OF TABLES
TABLE
PAGE
SECTION 1 - GENERAL INFORMATION
1-1. Technical Characteristics 1-9
1-2. Tube and Semiconductor Complement 1-11
SECTION 3 - OPERATION
3-1. Power Amplifier and Grid Networks - Controls/
Indicators 3-4
3-2. Operating Controls and Metering - Controls/Indicators 3-6
3-3. Solid- State Exciter and Magniphase - Controls/
Indicators 3-10
3-4. Control Section - Controls/Indicators 3-14
3-5. Typical Voltage and Current Values 3-17
Change 5 vii

TYPE 316F/315F
GENERAL INFORMATION
107000.41
ET1.1.7
Figure 1-1. Type 316F/315F AM Broadcast Transmitter, Front View
1-0

TYPE 316F/315F
GENERAL INFORMATION
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SECTION 1
GENERAL INFORMATION
1-1. INTRODUCTION.
This technical manual contains instructions for the installation,
operation and maintenance of the Continental Electronics Type 316F
and Type 315F AM Broadcast Transmitters. The Type 316F provides a
nominal rf output power of 10 kW while the Type 315F Transmitter
provides a nominal output power of 5 kW. These transmitters are
essentially identical mechanically and electrically.
The Type 316F/315F Transmitter is completely self-contained, in
that, no external driver, exciter, or power supply units are required.
Only an audio input, a transmitting antenna, and a source of 230/208
volt, three-phase, ac primary power are required for operation.
The Type 316F/315F Transmitter is tunable to any fixed operating
frequency between 535 kHz and 1620 kHz. Since the transmitter is
housed in a compact cabinet which measures 77" high, 67" wide and
25" deep, it occupies only 12- square feet of floor space.
Additional features included in the transmitter are the built-in,
solid-state Magniphase e antenna protection circuit; on- the- air
operation in five seconds from a cold start; vacuum capacitors
used in rf output network; solid-state rectifiers; simplified
control circuit for overload recycling and automatic cooling hold-
over after shutdown; wired for operational remote control and avail-
ability of power cutback options.
1-2. OPTIONAL EQUIPMENT AND CIRCUITRY.
The Type 316F and 315F Transmitters can be provided with optional
remote operation, and/or power- cutback circuits, which facilitate
instantaneous operational changes. The power cutback circuitry
normally provides a reduction from 10 kW to 5 kW in the Type 316F
Transmitter and from 5 kW to 1 kW in the Type 315F Transmitter.
However, other levels of power cutback are available by special order.
- Registered Trademark
1-1

TYPE 316F/315F
GENERAL INFORMATION
When the Type 316F/315F is purchased for any other mode of
operation, other than the standard 316F or 315F, the necessary
information and material are supplied for the additional options.
These transmitters also may be supplied for 50- cycle primary
power operation.
1-3. GENERAL DESCRIPTION ( Refer to Figures 1-1 through 1-3).
The Type 316F/315F ( 10 kW/5 kW) Transmitter is basically com-
posed of a solid-state exciter followed by a high- efficiency linear
amplifier. The solid-state exciter utilizes 19 transistors to
obtain a fully modulated 40- watt carrier output, which drives the
high- efficiency linear amplifier utilizing two air-cooled tetrodes.
Six transistors are used in the Magniphase antenna protective
circuit.
The Type 316F Transmitter uses two type 4CX15,000A tetrode tubes
operating at a plate voltage of 9 kVdc to produce a carrier output
power of 10,600 watts. The Type 315F Transmitter uses two type
4CX10,000D tetrode tubes operating at 7 kVdc to produce a carrier
output power of 5,500 watts. Since the major difference between
the 316F and the 315F is the screen supply, the PA filament trans-
formers, and the HV plate transformer, a single description is
suitable for both transmitters.
To facilitate servicing of the transmitter, easy access to the
cabinet interior is provided by two full-length rear doors, two
front doors covering the lower compartments, and another door on
the upper left- front of cabinet, which allows easy removal of the
PA tubes and access to the PA grid networks. In addition, the
controls, indicator lamps and meters are mounted on a hinged swing-
down panel, located on the upper right- front position of cabinet.
Furthermore, the exciter and Magniphase units are also mounted on
a hinged swing- down panel, thus exposing wiring and components
behind the panel.
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1-2
Change 5

TYPE 316F/315F
GENERAL INFORMATION
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r.cm.e•e.
POWER
AMPLIFIER
SOLID-STATE
1 EXCITER
AND
NIAGNIPHASE
+120 Vdc
POWER
POWER
e AMPLIFIER
GRID
- NETWORKS
OPERATING
CONTROLS
AND
METERING
11176004f
Figure 1-2. Type 316F/315F AM Broadcast Transmitter,
Showing Major Sections, Doors Open, Front View
ET1•14
1!-3

TYPE 316F/315F
GENERAL INFORMATION
•
RF
OUTPUT —
N ETINO R KS
HIGH
VOLTAGE
AND —
BIAS
SUPPLIES
107600-85
POWER
AMPLIFIER
PA
—FILAMENT
SUPPLIES
PA TUBES-
- COOLING
BLOWER
HIGH
VOLTAGE
AND
SCREEN
SUPPLIES
REV A ET1-1.9
Figure 1-3. Type 316F/315F AM Broadcast Transmitter,
Showing Major Sections, Doors Open, Rear View
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1-4

TYPE 315F/316F
GENERAL INFORMATION
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1-4. SOLID-STATE EXCITER.
The solid-state exciter includes a crystal oscillator with pro-
vision for switching in either one of two vacuum- type ovenless
crystals, four rf buffer amplifier stages, the 40- watt power
amplifier output stage, audio amplifiers driving the modulator,
envelope feedback rectifier and the Magniphase antenna protective
circuit.
The modulation technique is similar to plate modulation of
vacuum tube amplifiers in that a class B modulator is used to
modulate the collector voltage of the rf output stage. The rf
stage driving the 40- watt modulated amplifier is also collector
modulated to improve linearity.
The system employs a unique class B modulator circuit in which
no modulation transformers or reactors are required. The modulator
is driven from a direct- coupled phase inverter and since the entire
system is devoid of audio coupling transformers, negative feedback,
derived from the output rf envelope, can be used to further improve
the audio performance characteristics of the transmitter.
As mentioned earlier, the exciter includes the Continental
Electronics Magniphase Antenna Protective Circuit. A coupling
device placed in the rf output line of the transmitter, effectively
measures the impedance at that point and the derived samples of
voltage and current are used to null the output of a diode rectifier
circuit when normal conditions prevail. A change in load
conditions such as lightning strikes, static discharges or
antenna component arc-overs will cause the diode circuit to
conduct instantaneously. The voltage derived from the diode
circuit will then drive a one-shot multivibrator, which generates
a rectangular pulse of 150- millisecond duration, which in turn,
removes the rf excitation from the transmitter. The 150-
millisecond rf cut-off period is sufficient for the antenna
arc to clear itself, but short enough in time to be heard only
as a slight click on the transmitted program.
1-5. POWER AMPLIFIER.
Each transmitter uses only two tubes of a single type as
previously mentioned. The two PA tubes are arranged in a high-
efficiency linear amplifier circuit in which one tube, called
the carrier amplifier, supplies essentially all of the transmitter
output power in the absence of modulation. As modulation is

TYPE 315F/316F
GENERAL INFORMATION
applied, the other tube, called the peak amplifier, begins to
contribute power until at 100% modulation, each tube is supplying
one-half the peak power output of the transmitter. Unlike the
conventional linear amplifier, which operates at only 30% plate
efficiency, the high- efficiency linear amplifier operates at
60% plate efficiency by utilizing the carrier amplifier at its
most efficient condition of rf plate voltage swing. The carrier
tube operates as a class AB' amplifier. That is, it has a plate
current conduction angle greater than 180° and is not driven into
grid current conduction. With no modulation applied, the carrier
tube is driven to its maximum rf plate voltage swing.
The peak tube operates as a class C amplifier, that is, it
has a plate current conduction angle of less than 180°, but unlike
most class C amplifiers, the peak tube is not driven into grid
current conduction. With no modulation applied, the peak tube is
driven just slightly into plate conduction, drawing a small plate
current and contributing only slightly to the transmitter power
output. As modulation is applied, the plate current and power
output increase until at 100% modulation, the peak tube is driven
to its maximum rf plate voltage swing and is operating at about
75% plate efficiency.
Refer to the Theory of Operation, Section 4, for a detailed
theoretical description of the high- efficiency linear amplifier
under the title of Power Amplifier.
1-6. HARMONIC FILTER.
The output harmonic filter network is enclosed in an aluminum
shield box within the transmitter cabinet. The shield box is
insulated from the cabinet and grounded at only one point near the
PA tube sockets. This aluminum box plus the cabinet shell, produces
double rf shielding, which minimizes rf radiation from the
transmitter enclosure. In addition to the low-pass 90° interplate
"Pi" network, the harmonic filter also utilizes another " Pi"
network coupled with a " Tee" network. The shunt element, of the
"Tee" network, is a series- resonant circuit- tuned to the second
harmonic of the transmitter operating frequency. The output
inductor of the " Tee" network has a portion of its turns parallel
resonated with a fixed condenser at the third harmonic of the
operating frequency. Vacuum condensers are used in all of the
shunt elements of the harmonic filter to conserve space and
minimize arcing.
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