103 FREEDOM DRIVE P.O. BOX 525 LAWRENCE, PA 15055-0525 USA
(724) 873-8100 • FAX (724) 873-8105
www.axcera.com • info@axcera.com
UHF Analog Driver/Transmitter Chapter 1, Introduction
Chapter 1
Introduction
This manual explains the installation,
setup, alignment, and maintenance
procedures for the Innovator LX Series
UHF analog modular driver/transmitter.
It is important that you read all of the
instructions, especially the safety
information in this chapter, before you
begin to install or operate the unit.
1.1 Manual Overview
This instruction manual is divided into
five chapters and supporting appendices.
Chapter 1, Introduction, contains
information on the assembly numbering
system used in the manual, safety,
maintenance, return procedures, and
warranties. The second chapter describes
the driver/transmitter and includes
discussions on system control and status
indicators and remote control
connections. Chapter 3 explains how to
unpack, install, setup, and operate the
driver/transmitter. Chapter 4 contains
circuit-level descriptions for boards and
board-level components in the
driver/transmitter. Chapter 5, Detailed
Alignment Procedures, provides
information on adjusting the system
assemblies for optimal operation. The
appendices contain assembly and
subassembly drawings and parts lists,
and system specifications.
1.2 Assembly Designators
Axcera has assigned assembly numbers,
such as Ax (x=1,2,3…), to all assemblies,
modules, and boards that are referenced
in the text of this manual and shown on
the block diagrams and interconnect
drawings provided in the appendices.
These supporting documents are
arranged in increasing numerical order in
the appendices. Section titles in the text
for assembly or module descriptions or
alignment procedures contain the
associated part number(s) and the
relevant appendix that contains the
drawings for that item.
1.3 Safety
The UHF drivers and transmitters
manufactured by Axcera are designed to
be easy to use and repair while providing
protection from electrical and mechanical
hazards. Listed throughout the manual
are notes, cautions, and warnings
concerning possible safety hazards that
may be encountered while operating or
servicing the driver/transmitter. Please
review these warnings and familiarize
yourself with the operation and servicing
procedures before working on the
driver/transmitter.
Read All Instructions – All of the
operating and safety instructions should
be read and understood before operating
this equipment.
Retain Manuals – The manuals for the
driver/transmitter should be retained at
the transmitter site for future reference.
We provide two sets of manuals for this
purpose; one set can be left at the office
while one set can be kept at the site.
Heed all Notes, Warnings, and
Cautions – All of the notes, warnings,
and cautions listed in this safety section
and throughout the manual must be
followed.
Follow Instructions – All of the
operating and use instructions for the
driver/transmitter should be followed.
Cleaning – Unplug or otherwise
disconnect all power from the equipment
before cleaning. Do not use liquid or
aerosol cleaners. Use a damp cloth for
cleaning.
Ventilation – Openings in the cabinets
and module front panels are provided for
LX Series, Rev. 0 1-1
UHF Analog Driver/Transmitter Chapter 1, Introduction
ventilation. To ensure the reliable
operation of the driver/transmitter, and
to protect the unit from overheating,
these openings must not be blocked.
Servicing – Do not attempt to service
this product yourself until becoming
familiar with the equipment. If in doubt,
refer all servicing questions to qualified
Axcera service personnel.
Replacement Parts – When
replacement parts are used, be sure that
the parts have the same functional and
performance characteristics as the
original part. Unauthorized substitutions
may result in fire, electric shock, or other
hazards. Please contact the Axcera
Technical Service Department if you have
any questions regarding service or
replacement parts.
1.4 Maintenance
The Innovator LX Series
Driver/Transmitter is designed with
components that require little or no
periodic maintenance except for the
routine cleaning of the fans and the front
panels of the modules.
The amount of time between cleanings
depends on the conditions within the
transmitter room. While the electronics
have been designed to function even if
covered with dust, a heavy buildup of
dust, dirt, or insects will affect the
cooling of the components. This could
lead to a thermal shutdown or the
premature failure of the affected module.
When the front panels of the modules
become dust covered, the top covers
should be taken off and any accumulated
foreign material should be removed. A
vacuum cleaner, utilizing a small, wandtype attachment, is an excellent way to
suction out the dirt. Alcohol and other
cleaning agents should not be used
unless you are certain that the solvents
will not damage components or the silkscreened markings on the modules and
boards. Water-based cleaners can be
used, but do not saturate the
components. The fans and heatsinks
should be cleaned of all dust or dirt to
permit the free flow of air for cooling
purposes.
It is recommended that the operating
parameters of the driver/transmitter be
recorded from the LEDs on the modules
and the LCD system metering on the
control/monitoring module at least once
a month. It is suggested that this data be
retained in a rugged folder or envelope.
1.5 Material Return Procedure
To insure the efficient handling of
equipment or components that have been
returned for repair, Axcera requests that
each returned item be accompanied by a
Material Return Authorization Number
(MRA#).
An MRA# can be obtained from any
Axcera Field Service Engineer by
contacting the Axcera Field Service
Department at (724) 873-8100 or by fax
at (724) 873-8105. This procedure
applies to all items sent to the Field
Service Department regardless of
whether the item was originally
manufactured by Axcera.
When equipment is sent to the field on
loan, an MRA# is included with the unit.
The MRA# is intended to be used when
the unit is returned to Axcera. In
addition, all shipping material should be
retained for the return of the unit to
Axcera.
Replacement assemblies are also sent
with an MRA# to allow for the proper
routing of the exchanged hardware.
Failure to close out this type of MRA# will
normally result in the customer being
invoiced for the value of the loaner item
or the exchange assembly.
When shipping an item to Axcera, please
include the MRA# on the packing list and
on the shipping container. The packing
slip should also include contact
LX Series, Rev. 0 1-2
UHF Analog Driver/Transmitter Chapter 1, Introduction
information and a brief description of why
the unit is being returned.
Please forward all MRA items to:
AXCERA, LLC
103 Freedom Drive
P.O. Box 525
Lawrence, PA 15055-0525 USA
For more information concerning this
procedure, call the Axcera Field Service
Department.
Axcera can also be contacted through email at info@axcera.com and on the
Web at www.axcera.com.
1.6 Limited One-Year Warranty for
Axcera Products
Axcera warrants each new product that
it has manufactured and sold against
defects in material and workmanship
under normal use and service for a
period of one (1) year from the date of
shipment from Axcera's plant, when
operated in accordance with Axcera's
operating instructions. This warranty
shall not apply to tubes, fuses,
batteries, or bulbs.
Warranties are valid only when and if
(a) Axcera receives prompt written
notice of breach within the period of
warranty, (b) the defective product is
properly packed and returned by the
buyer (transportation and insurance
prepaid), and (c) Axcera determines, in
its sole judgment, that the product is
defective and not subject to any misuse,
neglect, improper installation,
negligence, accident, or (unless
authorized in writing by Axcera) repair
or alteration. Axcera's exclusive liability
for any personal and/or property
damage (including direct, consequential,
or incidental) caused by the breach of
any or all warranties, shall be limited to
the following: (a) repairing or replacing
(in Axcera's sole discretion) any
defective parts free of charge (F.O.B.
Axcera’s plant) and/or (b) crediting (in
Axcera's sole discretion) all or a portion
of the purchase price to the buyer.
Equipment furnished by Axcera, but not
bearing its trade name, shall bear no
warranties other than the special hoursof-use or other warranties extended by
or enforceable against the manufacturer
at the time of delivery to the buyer.
NO WARRANTIES, WHETHER
STATUTORY, EXPRESSED, OR
IMPLIED, AND NO WARRANTIES OF
MERCHANTABILITY, FITNESS FOR
ANY PARTICULAR PURPOSE, OR
FREEDOM FROM INFRINGEMENT,
OR THE LIKE, OTHER THAN AS
SPECIFIED IN PATENT LIABILITY
ARTICLES, AND IN THIS ARTICLE,
SHALL APPLY TO THE EQUIPMENT
FURNISHED HEREUNDER.
LX Series, Rev. 0 1-3
UHF Analog Driver/Transmitter Chapter 1, Introduction
FWARNING!!!
×HIGH VOLTAGEØ
DO NOT ATTEMPT TO REPAIR OR TROUBLESHOOT THIS EQUIPMENT UNLESS
YOU ARE FAMILIAR WITH ITS OPERATION AND EXPERIENCED IN
SERVICING HIGH VOLTAGE EQUIPMENT. LETHAL VOLTAGES ARE PRESENT
WHEN POWER IS APPLIED TO THIS SYSTEM. IF POSSIBLE, TURN OFF
POWER BEFORE MAKING ADJUSTMENTS TO THE SYSTEM.
« RADIO FREQUENCY RADIATION HAZARD «
MICROWAVE, RF AMPLIFIERS AND TUBES GENERATE HAZARDOUS RF
RADIATION THAT CAN CAUSE SEVERE INJURY INCLUDING CATARACTS,
WHICH CAN RESULT IN BLINDNESS. SOME CARDIAC PACEMAKERS MAY BE
AFFECTED BY THE RF ENERGY EMITTED BY RF AND MICROWAVE
AMPLIFIERS. NEVER OPERATE THE TRANSMITTER SYSTEM WITHOUT A
PROPERLY MATCHED RF ENERGY ABSORBING LOAD ATTACHED. KEEP
PERSONNEL AWAY FROM OPEN WAVEGUIDES AND ANTENNAS. NEVER LOOK
INTO AN OPEN WAVEGUIDE OR ANTENNA. MONITOR ALL PARTS OF THE RF
SYSTEM FOR RADIATION LEAKAGE AT REGULAR INTERVALS.
LX Series, Rev. 0 1-4
UHF Analog Driver/Transmitter Chapter 1, Introduction
EMERGENCY FIRST AID INSTRUCTIONS
Personnel engaged in the installation, operation, or maintenance of this equipment are urged to become
familiar with the following rules both in theory and practice. It is the duty of all operating personnel to be
prepared to give adequate Emergency First Aid and thereby prevent avoidable loss of life.
RESCUE BREATHING
1. Find out if the person is
breathing.
You must find out if the person
has stopped breathing. If you
think he is not breathing, place
him flat on his back. Put your ear
close to his mouth and look at his
chest. If he is breathing you can
feel the air on your cheek. You
can see his chest move up and
down. If you do not feel the air
or see the chest move, he is not
breathing.
2. If he is not breathing, open
the airway by tilting his head
backwards.
Lift up his neck with one hand
and push down on his forehead
with the other. This opens the
airway. Sometimes doing this will
let the person breathe again by
himself.
SKIN REDDENED: Apply ice cold water to burned
area to prevent burn from going deeper into skin
tissue. Cover area with clean sheet or cloth to keep
away air. Consult a physician.
SKIN BLISTERED OR FLESH CHARRED: Apply ice
cold water to burned area to prevent burn from
going deeper into skin tissue.
3. If he is still not breathing,
begin rescue breathing.
-Keep his head tilted backward.
Pinch nose shut.
-Put your mouth tightly over his
mouth.
-Blow into his mouth once every
five seconds
-DO NOT STOP rescue breathing
until help arrives.
LOOSEN CLOTHING - KEEP
WARM
Do this when the victim is
breathing by himself or help is
available. Keep him as quiet as
possible and from becoming
chilled. Otherwise treat him for
shock.
BURNS
Cover area with clean sheet or cloth to keep away
air. Treat victim for shock and take to hospital.
EXTENSIVE BURN - SKIN BROKEN: Cover area with
clean sheet or cloth to keep away air. Treat victim
for shock and take to hospital.
LX Series, Rev. 0 1-5
UHF Analog Driver/Transmitter Chapter 1, Introduction
Note: Because of possible FCC assigned offset, check for the assigned Carrier
Frequency as written on License.
UHF Channels NTSC Standard IF, 45.75 MHz
Visual Carrier Frequency (MHz)
Channel Nominal Minus Plus Nominal Nominal Minus Plus
UHF Analog Driver/Transmitter Chapter 1, Introduction
USEFUL CONVERSION FACTORS
TO CONVERT FROM TO MULTIPLY BY
mile (US statute) kilometer (km) 1.609347
inch (in) millimeter (mm) 25.4
inch (in) centimeter (cm) 2.54
inch (in) meter (m) 0.0254
foot (ft) meter (m) 0.3048
yard (yd) meter (m) 0.9144
mile per hour (mph) kilometer per hour(km/hr) 1.60934
mile per hour (mph) meter per second (m/s) 0.44704
pound (lb) kilogram (kg) 0.4535924
gallon (gal) liter 3.7854118
U.S. liquid
(One U.S. gallon equals 0.8327 Canadian gallon)
fluid ounce (fl oz) milliliters (ml) 29.57353
British Thermal Unit watt (W) 0.2930711
per hour (Btu/hr)
horsepower (hp) watt (W) 746
NOMENCLATURE OF FREQUENCY BANDS
FREQUENCY RANGE DESIGNATION
3 to 30 kHz VLF - Very Low Frequency
30 to 300 kHz LF - Low Frequency
300 to 3000 kHz MF - Medium Frequency
3 to 30 MHz HF - High Frequency
30 to 300 MHz VHF - Very High Frequency
300 to 3000 MHz UHF - Ultrahigh Frequency
3 to 30 GHz SHF - Superhigh Frequency
30 to 300 GHz EHF - Extremely High Frequency
LETTER DESIGNATIONS FOR UPPER FREQUENCY
BANDS
LETTER FREQ. BAND
L 1000 - 2000 MHz
S 2000 - 4000 MHz
C 4000 - 8000 MHz
X 8000 - 12000 MHz
Ku 12 - 18 GHz
K 18 - 27 GHz
Ka 27 - 40 GHz
V 40 - 75 GHz
W 75 - 110 GHz
LX Series, Rev. 0 1-11
UHF Analog Driver/Transmitter Chapter 1, Introduction
ABBREVIATIONS/ACRONYMS
AC Alternating Current
AFC Automatic Frequency Control
ALC Automatic Level Control
AM Amplitude modulation
AGC Automatic Gain Control
AWG American wire gauge
BER Bit Error Rate
BW Bandwidth
DC Direct Current
D/A Digital to analog
dB Decibel
dBm Decibel referenced to 1 milliwatt
dBmV Decibel referenced to 1 millivolt
dBw Decibel referenced to 1 watt
FEC Forward Error Correction
FM Frequency modulation
Hz Hertz
ICPM Incidental Carrier Phase Modulation
I/P Input
IF Intermediate Frequency
LED Light emitting diode
LSB Lower Sideband
MPEG Motion Pictures Expert Group
O/P Output
PLL Phase Locked Loop
UHF Analog Driver/Transmitter Chapter 1, Introduction
0 -10 -20 -30 -40 -50 -60
-70
N
dB
RETURN LOSS VS. VSWR
R
E
T
U
R
L
O
S
S
1.001 1.01 1.1 2.0
VSWR
LX Series, Rev. 0 1-13
UHF Analog Driver/Transmitter Chapter 2, System Description
& Remote Control Connections
Chapter 2
System Description & Remote Control Connections
The analog transmitters in the Innovator
LX Series are complete 10W to 100W
UHF Analog internally diplexed modular
television transmitters that operate at a
nominal visual output power of 10 to 100
watts peak sync and an average aural
output power of 1 to 10 watts, at an A/V
ratio of 10 dB, 10% sound, or .5 to 5
watts at 13 dB, 5% sound.
The LX Series can also be used as a
driver. The output power of the driver is
The chassis assembly is factory set for
operation using 110 VAC or 220 VAC. All
of the modules except the power
amplifier module and the power supply
section of the Control & Monitoring/Power
Supply Module, plug directly into a
backplane board. The backplane board
provides module to module
interconnection as well as interconnection
to remote command and control
connectors.
2.1.1 (A2) Modulator Module
Assembly (Appendix B)
NOTE: The Modulator module is not
present in a translator system
Power Amplifier Module, used
Driver Amplifier Module, used
determined by the level needed to attain
the full output power of the transmitter.
The driver’s maximum output is 7 Watts
peak of sync.
2.1 System Overview
The Analog LX Series driver/transmitter
is made up of the modules and
assemblies listed in Table 2-1.
TRAY/ASSEMBLY NAME
Modulator Module (not
present in translator)
in 10-100 Watt Transmitters
in high power transmitters
The (A2) Modulator Assembly contains
the Modulator Board. The modulator is
broadcast quality and provides front
LX Series, Rev. 0 2-1
UHF Analog Driver/Transmitter Chapter 2, System Description
& Remote Control Connections
panel access to control and monitoring
points. The video level is controlled
through a sync tip clamp and sync and
white clipping circuitry. The IF oscillator
is oven controlled and locked to a 10 MHz
reference for stability. The IF signal is fed
through a SAW filter for precise sideband
shaping. The Modulator operates using
Table 2-2. Modulator Front Panel Switch
SWITCH FUNCTION
When Manual Clamp is selected, the video level is set by the
Manual Bias Pot R67 located on the board. (NOTE: The pot is
MAN/AUTO CLAMP
SW1
Table 2-3. Modulator Front Panel Status Indicators
LED FUNCTION
AUR UNLOCK
DS5 (Red)
VIS UNLOCK
DS6 (Red)
AUD OV DEV
DS4 (Red)
VIDEO LOSS
DS1 (Red)
OVER MOD
DS3 (Red)
ALT IF
DS7 (Green)
10 MHz PRES
DS2 (Green)
Table 2-4. Modulator Front Panel Control Adjustments
POTENTIOMETERS
Video Gain (R42) Adjusts the level of the output video.
Visual Level (R214) Adjusts the Visual IF level that combines with the Aural IF.
Aural Level (R243) Adjusts the Aural IF level that combines with the Visual IF.
MONO (R110) Adjusts the deviation level of the balanced audio input.
STEREO (R132) Adjusts the deviation level of the composite audio input.
SAP/PRO (R150) Adjusts the deviation level of the subcarrier audio input.
Table 2-5. Modulator Front Panel Sample
SMA CONNECTOR DESCRIPTION
MOD IF SAMPLE (J10) Sample of the combined Aural IF and Visual IF signals.
factory set and needs no adjustment by the customer).
When Auto Clamp is selected, the video level control circuit
will automatically increase or decrease the video to maintain
the desired video level.
When lit it indicates that the 4.5 MHz VCO and the 10 MHz reference
are not PLL locked.
When lit it indicates that the 45.75 MHz VCXO and the 10 MHz
reference signal are not PLL locked.
When lit it indicates the deviation level is more than ±80kHz
When lit it indicates the Video Input to the transmitter is lost.
When lit it indicates the Video input level is too high.
When lit it indicates that external or alternate 4.5MHZ is present.
When lit it indicates that a 10MHz reference is present to the
transmitter.
either the baseband audio and video
inputs or the 4.5-MHz composite input to
produce a diplexed, modulated, and onchannel frequency visual + aural RF
output that is cabled to the IF Processing
Module.
DESCRIPTION
LX Series, Rev. 0 2-2
UHF Analog Driver/Transmitter Chapter 2, System Description
& Remote Control Connections
2.1.2 (A3) IF Processor Module
Assembly (Appendix B)
The (A3) IF Processor Assembly contains
the IF Processor Board . The IF Processor
provides pre-correction to ensure
broadcast quality output signal. The precorrection consists of amplitude linearity
correction, Incidental Carrier Phase
Modulation (ICPM) correction and
frequency response correction.
The IF Processor module is configured
either for an analog or digital system.
Pin 13C of the IF Processor module is
grounded in analog systems and left not
connected in digital systems. An IF
Processor Interlock signal is used to
report the presence of the IF Processor
module to the Control Monitoring board.
If the IF Processor interlock signal is not
present, the LX Series 100 Watt
Transmitter/Exciter Driver RF output is
Muted (turned off). If an analog IF
Processor module is installed and the
Modulation Present signal is not true,
the LX Series 100 Watt Transmitter /
Exciter Driver output is Muted (turned
off).
The Control & Monitoring/Power Supply
module uses the IF Processor module for
System output power control. Through
the front panel display or a remote
interface, an operator can set the
transmitter's RF output power. The
range of RF power adjustment is
between 0% (full off) and 105% (full
power plus). A front panel IF Processor
module potentiometer sets the upper
limit of RF power at 120%. The
system's Control Monitoring board
compares the RF Power Monitoring
module RF power level with the desired
level and uses the IF Power Control PWM
line to correct for errors.
In digital systems, a digital level control
(DLC) voltage is generated on the IF
Processor module and sent to an
external digital modulator (DT1C). RF
power control is implemented by
changing the DLC voltage provided to
the external digital modulator. The 'RF
High' potentiometer sets the upper
adjusted range of RF control circuit
output to 120%.
The IF Processor module provides a
reference ALC voltage to the system's
Upconverter. When the ALC voltage
decreases, the Upconverter
automatically lowers the system output
power through the AGC circuits.
The IF Processor module has a front
panel switch to select Auto or Manual
ALC. When Manual ALC is selected, the
reference ALC voltage is set by a front
panel potentiometer. In this condition,
the RF power level control circuit is
removed from use. When the ALC select
switch is changed to Auto, the RF power
level control circuit will start at low
power and increase the RF output until
the desired output power is attained.
The IF Processor module Modulation
Present signal is monitored. If the
modulation level is too low or nonexistent, a Modulation Present fault is
reported to the Control Monitoring
board. When the controller detects this
fault, it can be set to Automatically Mute
LX Series, Rev. 0 2-3
UHF Analog Driver/Transmitter Chapter 2, System Description
& Remote Control Connections
the transmitter or in Manual mode the
transmitter will continue to operate at
25% output.
The IF Processor module Input Signal
level is monitored. If the signal level is
too low or non-existent, an Input fault is
Table 2-6. IF Processor Front Panel Switch
SWITCH FUNCTION
When Manual ALC is selected, the reference ALC voltage is set
by the ALC Gain front panel potentiometer.
MAN/AUTO ALC
Table 2-7. IF Processor Front Panel Status Indicators
LED FUNCTION
INPUT FAULT (Red)
ALC Fault (Red)
MUTE (Red)
Table 2-8. IF Processor Front Panel Control Adjustments
POTENTIOMETERS
FREQUENCY
RESPONSE
EQUALIZER
ALC GAIN
MAN GAIN
LINEARITY
CORRECTION
Table 2-9. IF Processor Front Panel Sample
SMA CONNECTOR DESCRIPTION
IF SAMPLE Sample of the pre-corrected IF output of the IF Processor
When Auto ALC is selected, the IF level control circuit will
automatically increase the IF output until the desired output
power is attained.
When lit it indicates that there is a loss of the IF Input signal to the
IF Processor. Transmitter can be set to Mute on an IF Input Fault.
When lit it indicates that the required gain to produce the desired
output power level has exceeded the operational range of the ALC
circuit. The LED will also be lit when ALC is in Manual.
When lit it indicates that the IF input signal is cut back but the
enable to the Power Supply is present and the +32 VDC remains on.
These three variable resistors, R103, R106 & R274, adjust the
depth of gain for the three stages of frequency response correction.
Adjusts the gain of the transmitter when the transmitter is in the
Auto ALC position.
Adjusts the gain of the transmitter when the transmitter is in the
Manual ALC position.
These three variable resistors adjust the threshold cut in for the
three stages of linearity pre-correction. R211 and R216, the top
two pots, are adjusted to correct for in phase amplitude distortions.
R 231, the bottom pot, is adjusted to correct for quadrature phase
distortions.
reported on the Control Monitoring
board. When the IF Processor board
detects an Input Signal fault it
automatically Mutes the transmitter.
The system controller does not Mute on
an IF Processor Input fault.
DESCRIPTION
LX Series, Rev. 0 2-4
UHF Analog Driver/Transmitter Chapter 2, System Description
& Remote Control Connections
2.1.3 (A5) LO/Upconverter Module
Assembly (Appendix B)
The LX Series Upconverter converts an
IF input signal to a RF output signal on
the desired channel frequency using a
high stability oven controlled oscillator
with very low phase noise and an
Automatic Level Control (ALC) for stable
output signal level.
Several control voltages are used for
transmitter power control. Automatic
gain control (AGC) circuits set the RF
output level of the transmitter system.
AGC #1 is provided by the
Transmitter/Exciter Driver Power
Amplifier module. This voltage is used
by the Upconverter to maintain a
constant RF output level at the Power
Amplifier module output. If this voltage
exceeds 0.9 VDC, the system is in an
over-drive condition. The 0.9 VDC overdriver threshold is set by a front panel
Upconverter module potentiometer.
When an over-drive condition is
detected, the Upconverter module
reduces its RF output level. For values
less than 0.9 VDC, the Upconverter uses
the AGC #1 voltage for automatic gain
control by setting it's RF output to
maintain AGC #1 equal to the AGC
voltage set by another front panel
potentiometer. When the Upconverter is
set for manual gain, the RF output of the
Upconverter is set by the front panel
AGC potentiometer. In manual gain
operation, the AGC #1 feedback voltage
from the PA is not used to adjust the RF
level unless an over-drive condition is
detected.
AGC #2 is provided by each of the
optional external amplifier modules.
Diodes are used in each of the external
amplifier forward power circuits to
capture the highest detected sample
voltage. This voltage is used by the
Upconverter to maintain a constant RF
output of the system. As with AGC #1,
the Upconverter module reduces its RF
output level if AGC #2 is too high. AGC
#1 and ACG #2 are diode ORed together
in the Upconverter gain circuit. Both
AGC voltages are first reduced by an onboard potentiometer before being
amplified. If an over-drive condition
does not exist, the higher of the two
AGC voltages is used to control the
Upconverter gain circuit. An AFC Voltage
is generated to control the VCXO of the
UHF Generator portion of the
Upconverter module. The typical AFC
voltage is 0.5 VDC but it can be as high
as +1.5 VDC.
The Upconverter can operate on either
it's internal 10 MHz source or on a 10
MHz external reference signal. When an
external 10 MHz source is present on
J10, it is automatically selected. An
external reference present signal is
provided to the controller for display
purposes. The selected 10 MHz signal
from the Upconverter is buffered then
sent to the backplane on two ports. One
port is sent to the Modulator module, if
present, and the other is routed to a
BNC connector (J11) on the backplane
for a system 10 MHz output signal.
A National Semiconductor frequency
synthesizer IC is used in the frequency
conversion of the IF signal to a RF
signal. The frequency synthesizer IC
uses a 10MHz reference frequency for
signal conversion. Typically the IF input
frequency is 45.75 MHz for analog
system and 44 MHz for DTV. To obtain
different output RF frequencies, the
synthesizer IC is serial programmed by
the Control Monitoring board. The part
is programmed to use a 5 kHz phase
detection frequency. With a 10 MHz
input signal, the R counter is set to
2000. With these settings the N counter
LX Series, Rev. 0 2-5
UHF Analog Driver/Transmitter Chapter 2, System Description
& Remote Control Connections
is set to the desired LO frequency in kHz
/ 5 kHz. The maximum LO frequency
setting with these parameters is
1310.715 MHz.
Example:
For a Frequency RF Out = 517.125 MHz,
N = 517125 kHz / 5 kHz = 103425
Table 2-10. LO/Upconverter Front Panel Switch
SWITCH FUNCTION
When Manual AGC is selected, the reference AGC voltage is
set by the AGC Manual Gain front panel potentiometer.
MAN/AUTO AGC
Table 2-11. LO/Upconverter Front Panel Status Indicator
LED FUNCTION
AGC CUTBACK
(Red)
Table 2-12. LO/Upconverter Front Panel Control Adjustments
POTENTIOMETERS
MAN GAIN ADJ
AGC CUTBACK ADJ
(AGC OVERRIDE)
Table 2-13. LO/Upconverter Front Panel Samples
SMA CONNECTOR DESCRIPTION
LO SAMPLE
RF SAMPLE Sample of the On Channel RF Output of the Upconverter
When Auto AGC is selected, the RF power level control circuit
will automatically increase the RF output until the desired
output power is attained.
When lit it indicates that the required gain to produce the desired
output power level has exceeded the level set by the AGC Cutback
(Override) adjust. Transmitter will cut back power to 25%
Adjusts the gain of the transmitter when the transmitter is in the
Manual AGC position.
Adjusts the point at which the transmitter will cut back in power
when the Transmitter is in the Auto AGC position.
Sample of the LO signal to the Upconverter as generated by the
UHF Generator Board.
An Upconverter PLL Lock indicator is
used to insure that the frequency control
circuits are operating properly. When
the Upconverter PLL is locked, the
frequency synthesizer IC is programmed
and the Power Amplifier module(s) can
be enabled.
The RF output of the LO/Upconverter
Module is at J23 on the rear chassis.
DESCRIPTION
LX Series, Rev. 0 2-6
UHF Analog Driver/Transmitter Chapter 2, System Description
8 A
4 A
& Remote Control Connections
2.1.4 (A4) Control/Power Supply
Module Assembly (110 VAC, or 220
VAC, Appendix B)
The (A4) Control & Monitoring/Power
Supply Assembly is configured at the
factory for operation at 110 VAC or 220
VAC. The assembly made up of a Control
Board, a Power Protection Board and a
Switch Board. The Assembly also
contains a switching power supply that
provides ±12 VDC to the rest of the
modules in the chassis and +32 VDC to
the Power Amplifier module.
The Assembly provides all transmitter
control and monitoring functions. The
Front panel LCD allows monitoring of
system parameters, including forward
and reflected power, transistor currents,
module temperatures and power supply
voltages.
Table 2-14. Controller/Power Supply Display
DISPLAY FUNCTION
A 4 x 20 display providing a four-line readout of the internal
LCD
functions, external inputs, and status. See Chapter 3,
Controller/Power Supply Display Screens, for a listing of displays.
Table 2-15. Controller/Power Supply Status Indicator
LED FUNCTION
OPERATE
(green)
FAULT
(red or green)
DC OK
( red or green )
When lit it indicates that the transmitter is in the Operate Mode. If
transmitter is Muted the Operate LED will stay lit, the transmitter
will remain in Operate, until the input signal is returned.
Red indicates that a problem has occurred in the transmitter. The
transmitter will be Muted or placed in Standby until the problem is
corrected.
Green indicates that the switchable fuse protected DC outputs that
connect to the modules in the transmitter are OK.
Table 2-16. Controller/Power Supply Control Adjustments
POTENTIOMETERS
DESCRIPTION
DISPLAY CONTRAST Adjusts the contrast of the display for desired viewing of screen.
LX Series, Rev. 0 2-7
UHF Analog Driver/Transmitter Chapter 2, System Description
& Remote Control Connections
2.1.5 (A6) Power Amplifier Module
Assembly, Exciter, 100W Transmitter
Appendix B)
NOTE: The (A6) Power Amplifier Module
Assembly is used in the 10-100 Watt
Transmitter.
The (A6) Power Amplifier Module
Assembly is made up of a Coupler Board
Assembly, an Amplifier Control Board, a
1 Watt Module Assembly, a 100W Driver
Board and a RES RF Module Pallet.
The Power Amplifier Module contains
Broadband LDMOS amplifiers that cover
the entire UHF band with no tuning
required. They amplify the RF to the
10W to 100W output power level of the
transmitter.
The Power Amplifier of the
Transmitter/Exciter Driver is used to
amplify the RF output of the
Upconverter module. A cable, located on
the rear chassis, connects the RF output
from the LO/Upconverter at J23 to J24
the RF input to the PA Assembly. This
module contains RF monitoring circuitry
for both an analog and a digital system.
Control and monitoring lines to the
Power Amplifier module are routed
through the floating blind-mate
connector of the Control &
Monitoring/Power Supply module.
The 100 Watt Transmitter/Exciter Driver
Power Amplifier module and any
External Amplifier modules contain the
same control and monitoring board.
This board monitors RF output power,
RF reflected power, the current draw of
amplifier sections, the supply voltage,
and the temperature of the PA heat sink.
The RF power detector circuit outputs
vary with operating frequency. These
circuits must be calibrated at their
intended operating frequency. Front
panel adjustment potentiometers are
used to calibrate the following:
Table 1: Power Amplifier Calibration
Adjustments in Analog Systems
R201 Reflected Power Cal
R202 Visual / Forward Power Cal
R203 Aural Power Cal
R204 Visual Offset Zero
R205 Aural Null
In analog systems, the Aural power of
an Exciter Driver Power Amplifier and
the Aural power of any external
amplifier will not be reported by the
system Control Monitoring module.
Additionally the Visual power of these
amplifiers, is reported as Forward Power
just like in digital systems. In analog
systems, aural and visual power will only
be reported for the final system RF
output.
In digital systems, the Forward power of
an Exciter Driver Power Amplifier and
the Forward power of any external
amplifier, is reported by the system
Control Monitoring module.
If the Control Monitoring module is
monitoring a 5-50 Watt digital or 10-100
Watt analog Transmitter, system power
is measured in the Power Amplifier
module. The wired connections are
transferred through the power supply
connector to the backplane board on a
five position header. All four positions
of control board switch SW1 must be set
on to route these lines as the system's
RF power signals. In systems of output
power greater than 50 Watts digital or
100 Watts analog, system power is
monitored by an external module that is
connected to TB31 and control board
SW1 switches must be set off.
The Forward Power of the
Transmitter/Exciter Driver Power
Amplifier module is routed to the
Upconverter module as AGC #1. A
system over-drive condition is detected
when this value rises above 0.9 VDC.
When an over-drive condition is
LX Series, Rev. 0 2-8
UHF Analog Driver/Transmitter Chapter 2, System Description
& Remote Control Connections
detected, the Upconverter module
reduces its RF output level. For values
Table 2-17. Power Amplifier Status Indicator
LED FUNCTION
ENABLED
(Green)
DC OK
(Green)
TEMP
(Green)
MOD OK
(Green)
Table 2-18. Power Amplifier Control Adjustments
POTENTIOMETERS
RFL CAL Adjusts the gain of the Reflected Power monitoring circuit
VISUAL CAL Adjusts the gain of the Visual / Forward Power monitoring circuit
AURAL CAL Adjusts the gain of the Aural Power monitoring circuit
VISUAL ZERO Adjusts the offset of the Forward Power monitoring circuit
AURAL NULL
Table 2-19. Power Amplifier Sample
DISPLAY FUNCTION
FWD SAMPLE RF sample of the amplified signal being sent out the module on J25.
When lit Green, it indicates that the PA is in the Operate Mode. If a
Mute occurs, the PA will remain Enabled, until the input signal is
returned.
When lit Green, it indicates that the fuse protected DC inputs to the
PA module are OK.
When lit Green, it indicates that the temperature of the heatsink
assembly in the module is below 78°C.
When lit Green, it indicates that the PA Module is operating and has
no faults.
Adjusts the offset of the Forward Power monitoring circuit based on
the Aural signal level.
less than 0.9 VDC, the Upconverter uses
this voltage for automatic gain.
DESCRIPTION
2.1.6 RF Output Assemblies
The RF output from the driver power
amplifier is at the RF output jack, an “N”
connector J25, PA RF Output, of the
chassis assembly. If this assembly is
used as a driver the output connects to
the input of the PA Assembly mounted
beneath the Exciter Assembly. If this
assembly is used as a 10W to 100W
transmitter, then the output connects
directly to the bandpass filter for the
system.
The RF output of the transmitter is
typically connected to a bandpass filter
and then to a trap filter mounted on the
rear of the assembly. The bandpass and
trap filters are tuned to eliminate
unwanted sideband and harmonic
LX Series, Rev. 0 2-9
frequencies. Located on the output of
the trap filter is a BNC output sample
jack that can be used for test purposes.
2.2 Control and Status
The control and status of the
exciter/amplifier Chassis assembly are
found by operating the front panel
display screen on the front of the
assembly. Detailed information on the
use of the screens is found in chapter 3.
2.2.1 Front Panel Display Screens
A 4 x 20 display located on the front of
the Control & Monitoring/Power Supply
Module is used in the LX Series
transmitter for control of the operation
UHF Analog Driver/Transmitter Chapter 2, System Description
& Remote Control Connections
and display of the operating parameters
of the transmitter.
2.3 System Operation
When the transmitter is in operate, as set
by the menu screen located on the
Control & Monitoring Module. The IF
Processor will be enabled, the mute
indicator on the front panel will be
extinguished. The +32 VDC stage of the
Power Supply in the Control & Monitoring
Module is enabled, the operate indicator
on the front panel is lit and the DC OK on
the front panel should also be green.
The enable and DC OK indicators on the
PA Module will also be green.
When the transmitter is in standby. The
IF Processor will be disabled, the mute
indicator on the front panel will be red.
The +32 VDC stage of the Power Supply
in the Control & Monitoring Module is
disabled, the operate indicator on the
front panel will be extinguished and the
DC OK on the front panel should remain
green. The enable indicator on the PA
Module is also extinguished.
If the transmitter does not switch to
Operate when the operate menu is
switched to Operate, check that all faults
are cleared and that the remote control
terminal block stand-by signal is not
active.
The transmitter can be controlled by the
presence of a modulated input signal. If
the input signal to the transmitter is lost,
the transmitter will automatically cutback
and the input fault indicator on the IF
Processor module will light. When the
video input signal returns, the
transmitter will automatically return to
full power and the input fault indicator
will be extinguished.
2.3.1 Principles of Operation
Operating Modes
This transmitter is either operating or in
standby mode. The sections below
discuss the characteristics of each of
these modes.
Operate Mode
Operate mode is the normal mode for
the transmitter when it is providing RF
power output. To provide RF power to
the output, the transmitter will not be in
mute. Mute is a special case of the
operate mode where the +32 VDC
section of the power supply is enabled
but there is no RF output power from
the transmitter. This condition is the
result of a fault condition that causes
the firmware to hold the IF Processor
module in a mute state.
Operate Mode with Mute Condition
The transmitter will remain in the
operate mode but will be placed in mute
when the following fault conditions
exists in the transmitter.
• Upconverter is unlocked
• Upconverter module is not present
• IF Processor module is not present
• Modulator (if present) is in
Aural/Visual Mute
Entering Operate Mode
Entering the operate mode can be
initiated a few different ways by the
transmitter control board. A list of the
actions that cause the operate mode to
be entered is given below:
• A low on the Remote Transmitter
Operate line.
• User selects "OPR" using switches
and menus of the front panel.
• Receipt of an “Operate CMD” over
the serial interface.
There are several fault or interlock
conditions that may exist in the
transmitter that will prevent the
LX Series, Rev. 0 2-10
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