UBS Axcera LU6000BT 6000-Watt UHF Transmitter User Manual Title Page LU6000BT

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INSTRUCTION MANUAL
INNOVATOR LX SERIES
UHF Analog Driver/Transmitter
(Preliminary)
AXCERA, LLC
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.
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.
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.
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.
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
LX Series, Rev. 0
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
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.
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.
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.
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.
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.
1.5 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#).
1.4 Maintenance
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.
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 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.
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
LX Series, Rev. 0
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
1-2
UHF Analog Driver/Transmitter
Chapter 1, Introduction
information and a brief description of why
the unit is being returned.
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.
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
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.
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.
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.
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
LX Series, Rev. 0
1-3
UHF Analog Driver/Transmitter
Chapter 1, Introduction
F WARNING!!!
× HIGH VOLTAGE Ø
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.
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
WARM
CLOTHING
KEEP
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
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.
LX Series, Rev. 0
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.
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
L.O.
(MHz)
Visual Carrier Frequency (MHz)
Crystal Frequency (MHz)
Channel
Nominal
Minus
Plus
Nominal
Nominal
Minus
Plus
14
471.25
471.24
471.26
517.00
64.625
64.62375
64.62625
15
477.25
477.24
477.26
523.00
65.375
65.37375
65.37625
16
483.25
483.24
483.26
529.00
66.125
66.12375
66.12625
17
489.25
489.24
489.26
535.00
66.875
66.87375
66.87625
18
495.25
495.24
495.26
541.00
67.625
67.62375
67.62625
19
501.25
501.24
501.26
547.00
68.375
68.37375
68.37625
20
507.25
507.24
507.26
553.00
69.125
69.12375
69.12625
21
513.25
513.24
513.26
559.00
69.875
69.87375
69.87625
22
519.25
519.24
519.26
565.00
70.625
70.62375
70.62625
23
525.25
525.24
525.26
571.00
71.375
71.37375
71.37625
24
531.25
531.24
531.26
577.00
72.125
72.12375
72.12625
25
537.25
537.24
537.26
583.00
72.875
72.87375
72.87625
26
543.25
543.24
543.26
589.00
73.625
73.62375
73.62625
27
549.25
549.24
549.26
595.00
74.375
74.37375
74.37625
28
555.25
555.24
555.26
601.00
75.125
75.12375
75.12625
29
561.25
561.24
561.26
607.00
75.875
75.87375
75.87625
30
567.25
567.24
567.26
613.00
76.625
76.62375
76.62625
31
573.25
573.24
573.26
619.00
77.375
77.37375
77.37625
32
579.25
579.24
579.26
625.00
78.125
78.12375
78.12625
33
585.25
585.24
585.26
631.00
78.875
78.87375
78.87625
34
591.25
591.24
591.26
637.00
79.625
79.62375
79.62625
35
597.25
597.24
597.26
643.00
80.375
80.37375
80.37625
36
603.25
603.24
603.26
649.00
81.125
81.12375
81.12625
37
609.25
609.24
609.26
655.00
81.875
81.87375
81.87625
38
615.25
615.24
615.26
661.00
82.625
82.62375
82.62625
39
621.25
621.24
621.26
667.00
83.375
83.37375
83.37625
40
627.25
627.24
627.26
673.00
84.125
84.12375
84.12625
41
633.25
633.24
633.26
679.00
84.875
84.87375
84.87625
42
639.25
639.24
639.26
685.00
85.625
85.62375
85.62625
43
645.25
645.24
645.26
691.00
86.375
86.37375
86.37625
LX Series, Rev. 0
1-6
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
L.O.
(MHz)
Visual Carrier Frequency (MHz)
Crystal Frequency (MHz)
Channel
Nominal
Minus
Plus
Nominal
Nominal
Minus
Plus
44
651.25
651.24
651.26
697.00
87.125
87.12375
87.12625
45
657.25
657.24
657.26
703.00
87.875
87.87375
87.87625
46
663.25
663.24
663.26
709.00
88.625
88.62375
88.62625
47
669.25
669.24
669.26
715.00
89.375
89.37375
89.37625
48
675.25
675.24
675.26
721.00
90.125
90.12375
90.12625
49
681.25
681.24
681.26
727.00
90.875
90.87375
90.87625
50
687.25
687.24
687.26
733.00
91.625
91.62375
91.62625
51
693.25
693.24
693.26
739.00
92.375
92.37375
92.37625
52
699.25
699.24
699.26
745.00
93.125
93.12375
93.12625
53
705.25
705.24
705.26
751.00
93.875
93.87375
93.87625
54
711.25
711.24
711.26
757.00
94.625
94.62375
94.62625
55
717.25
717.24
717.26
763.00
95.375
95.37375
95.37625
56
723.25
723.24
723.26
769.00
96.125
96.12375
96.12625
57
729.25
729.24
729.26
775.00
96.875
96.87375
96.87625
58
735.25
735.24
735.26
781.00
97.625
97.62375
97.62625
59
741.25
741.24
741.26
787.00
98.375
98.37375
98.37625
60
747.25
747.24
747.26
793.00
99.125
99.12375
99.12625
61
753.25
753.24
753.26
799.00
99.875
99.87375
99.87625
62
759.25
759.24
759.26
805.00
100.625
100.62375
100.62625
63
765.25
765.24
765.26
811.00
101.375
101.37375
101.37625
64
771.25
771.24
771.26
817.00
102.125
102.12375
102.12625
65
777.25
777.24
777.26
823.00
102.875
102.87375
102.87625
66
783.25
783.24
783.26
829.00
103.625
103.62375
103.62625
67
789.25
789.24
789.26
835.00
104.375
104.37375
104.37625
68
795.25
795.24
795.26
841.00
105.125
105.12375
105.12625
69
801.25
801.24
801.26
847.00
105.875
105.87375
105.87625
70
807.25
807.24
807.26
853.00
106.625
106.62375
106.62625
LX Series, Rev. 0
1-7
UHF Analog Driver/Transmitter
Note:
Chapter 1, Introduction
Because of possible FCC assigned offset, check for the assigned Carrier
Frequency as written on License.
UHF Frequency Assignments
Channel
Number
Bandwidth
(MHz)
Video
(MHz)
Color
(MHz)
Audio
(MHz)
14
470-476
471.25
474.83
475.75
15
476-482
477.25
480.83
481.75
16
482-488
483.25
486.83
487.75
17
488-494
489.25
492.83
493.75
18
494-500
495.25
498.83
499.75
19
500-506
501.25
504.83
505.75
20
506-512
507.25
510.83
511.75
21
512-518
513.25
516.83
517.75
22
518-524
519.25
522.83
523.75
23
524-530
525.25
528.83
529.75
24
530-536
531.25
534.83
535.75
25
536-542
537.25
540.83
541.75
26
542-548
543.25
546.83
547.75
27
548-554
549.25
552.83
553.75
28
554-560
555.25
558.83
559.75
29
560-566
561.25
564.83
565.75
30
566-572
567.25
570.83
571.75
31
572-578
573.25
576.83
577.75
32
578-584
579.25
582.83
583.75
33
584-590
585.25
588.83
589.75
34
590-596
591.25
594.83
595.75
35
596-602
597.25
600.83
601.75
36
602-608
603.25
606.83
607.75
37
608-614
609.25
612.83
613.75
38
614-620
615.25
618.83
619.75
39
620-626
621.25
624.83
625.75
40
626-632
627.25
630.83
631.75
41
632-638
633.25
636.83
637.75
42
638-644
639.25
642.83
643.75
43
644-650
645.25
648.83
649.75
LX Series, Rev. 0
1-8
UHF Analog Driver/Transmitter
Note:
Chapter 1, Introduction
Because of possible FCC assigned offset, check for the assigned
Carrier Frequency as written on License.
UHF Frequency Assignments
Channel
Number
Bandwidth
(MHz)
Video
(MHz)
Color
(MHz)
Audio
(MHz)
44
650-656
651.25
654.83
655.75
45
656-662
657.25
660.83
661.75
46
662-668
663.25
666.83
667.75
47
668-674
669.25
672.83
673.75
48
674-680
675.25
678.83
679.75
49
680-686
681.25
684.83
685.75
50
686-692
687.25
690.83
691.75
51
692-698
693.25
696.83
697.75
52
698-704
699.25
702.83
703.75
53
704-710
705.25
708.83
709.75
54
710-716
711.25
714.83
715.75
55
716-722
717.25
720.83
721.75
56
722-728
723.25
726.83
727.75
57
728-734
729.25
732.83
733.75
58
734-740
735.25
738.83
739.75
59
740-746
741.25
744.83
745.75
60
746-752
747.25
750.83
751.75
61
752-758
753.25
756.83
757.75
62
758-764
759.25
762.83
763.75
63
764-770
765.25
768.83
769.75
64
770-776
771.25
774.83
775.75
65
776-782
777.25
780.83
781.75
66
782-788
783.25
786.83
787.75
67
788-794
789.25
792.83
793.75
68
794-800
795.25
798.83
799.75
69
800-806
801.25
804.83
805.75
70
806-812
807.25
810.83
811.75
LX Series, Rev. 0
1-9
UHF Analog Driver/Transmitter
Chapter 1, Introduction
dBm, dBw, dBmV, dBµV, & VOLTAGE
EXPRESSED IN WATTS
50 Ohm System
WATTS
1,000,000,000,000
100,000,000,000
10,000,000,000
1,000,000,000
100,000,000
10,000,000
1,000,000
100,000
10,000
1,000
100
50
20
10
0.1
0.01
0.001
0.0001
0.00001
0.000001
0.0000001
0.00000001
0.000000001
0.0000000001
0.00000000001
0.000000000001
PREFIX
1 TERAWATT
100 GIGAWATTS
10 GIGAWATTS
1 GIGAWATT
100 MEGAWATTS
10 MEGAWATTS
1 MEGAWATT
100 KILOWATTS
10 KILOWATTS
1 KILOWATT
1 HECTROWATT
1 DECAWATT
1 WATT
1 DECIWATT
1 CENTIWATT
1 MILLIWATT
100 MICROWATTS
10 MICROWATTS
1 MICROWATT
100 NANOWATTS
10 NANOWATTS
1 NANOWATT
100 PICOWATTS
10 PICOWATTS
1 PICOWATT
dBm
dBw
+150
+140
+130
+120
+110
+100
+ 90
+ 80
+ 70
+ 60
+ 50
+ 47
+ 43
+ 40
+ 30
+ 20
+ 10
- 10
- 20
- 30
- 40
- 50
- 60
- 70
- 80
- 90
+120
+110
+100
+ 99
+ 80
+ 70
+ 60
+ 50
+ 40
+ 30
+ 20
+ 17
+ 13
+ 10
- 10
- 20
- 30
- 40
- 50
- 60
- 70
- 80
- 90
-100
-110
-120
dBm
dBµV
VOLTAGE
+137
+127
+117
+107
7.07V
2.24V
0.707V
224mV
77
67
57
47
TEMPERATURE CONVERSION
°F = 32 + [(9/5) °C]
°C = [(5/9) (°F - 32)]
LX Series, Rev. 0
1-10
UHF Analog Driver/Transmitter
Chapter 1, Introduction
USEFUL CONVERSION FACTORS
TO CONVERT FROM
TO
MULTIPLY BY
mile (US statute)
kilometer (km)
inch (in)
millimeter (mm)
inch (in)
centimeter (cm)
inch (in)
meter (m)
foot (ft)
meter (m)
yard (yd)
meter (m)
mile per hour (mph)
kilometer per hour(km/hr)
mile per hour (mph)
meter per second (m/s)
pound (lb)
kilogram (kg)
gallon (gal)
liter
U.S. liquid
(One U.S. gallon equals 0.8327 Canadian gallon)
fluid ounce (fl oz)
milliliters (ml)
British Thermal Unit
watt (W)
horsepower (hp)
watt (W)
1.609347
25.4
2.54
0.0254
0.3048
0.9144
1.60934
0.44704
0.4535924
3.7854118
29.57353
0.2930711
per hour (Btu/hr)
746
NOMENCLATURE OF FREQUENCY BANDS
FREQUENCY RANGE
DESIGNATION
3 to 30 kHz
30 to 300 kHz
300 to 3000 kHz
3 to 30 MHz
30 to 300 MHz
300 to 3000 MHz
3 to 30 GHz
30 to 300 GHz
VLF
LF
MF
HF
VHF
UHF
SHF
EHF
Very Low Frequency
Low Frequency
Medium Frequency
High Frequency
Very High Frequency
Ultrahigh Frequency
Superhigh Frequency
Extremely High Frequency
LETTER DESIGNATIONS FOR UPPER FREQUENCY
BANDS
LETTER
FREQ. BAND
Ku
Ka
LX Series, Rev. 0
1000 - 2000 MHz
2000 - 4000 MHz
4000 - 8000 MHz
8000 - 12000 MHz
12 - 18 GHz
18 - 27 GHz
27 - 40 GHz
40 - 75 GHz
75 - 110 GHz
1-11
UHF Analog Driver/Transmitter
Chapter 1, Introduction
ABBREVIATIONS/ACRONYMS
AC
Alternating Current
PCB
Printed circuit board
AFC
Automatic Frequency Control
QAM
Quadrature Amplitude Modulation
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
LX Series, Rev. 0
1-12
UHF Analog Driver/Transmitter
Chapter 1, Introduction
RETURN LOSS VS. VSWR
-10
-20
-30
N dB
-40
-50
-60
-70
1.001
1.01
1.1
VSWR
LX Series, Rev. 0
1-13
2.0
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.
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.
The LX Series can also be used as a
driver. The output power of the driver is
Table 2-1: LX Series Trays and Assemblies
ASSEMBLY DESIGNATOR
A2
A3
A4
A5
A6
OR A6
A11
A12
A20
TRAY/ASSEMBLY NAME
Modulator Module (not
present in translator)
IF Processor Module
Control/Power Supply Module
LO/Upconverter Module
Power Amplifier Module, used
in 10-100 Watt Transmitters
Driver Amplifier Module, used
in high power transmitters
Backplane Board
Switch Board
LCD Display Board
Exciter Amplifier Chassis Assembly,
110 VAC (or 220 VAC Appendix B)
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)
The (A2) Modulator Assembly contains
the Modulator Board. The modulator is
broadcast quality and provides front
NOTE: The Modulator module is not
present in a translator system
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
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.
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
factory set and needs no adjustment by the customer).
MAN/AUTO CLAMP
SW1
When Auto Clamp is selected, the video level control circuit
will automatically increase or decrease the video to maintain
the desired video level.
Table 2-3. Modulator Front Panel Status Indicators
LED
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)
FUNCTION
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.
Table 2-4. Modulator Front Panel Control Adjustments
POTENTIOMETERS
Video Gain (R42)
Visual Level (R214)
Aural Level (R243)
MONO (R110)
STEREO (R132)
SAP/PRO (R150)
DESCRIPTION
Adjusts the level of the output video.
Adjusts the Visual IF level that combines with the Aural IF.
Adjusts the Aural IF level that combines with the Visual IF.
Adjusts the deviation level of the balanced audio input.
Adjusts the deviation level of the composite audio input.
Adjusts the deviation level of the subcarrier audio input.
Table 2-5. Modulator Front Panel Sample
SMA CONNECTOR
MOD IF SAMPLE (J10)
LX Series, Rev. 0
DESCRIPTION
Sample of the combined Aural IF and Visual IF signals.
2-2
UHF Analog Driver/Transmitter
Chapter 2, System Description
& Remote Control Connections
2.1.2 (A3) IF Processor Module
Assembly (Appendix B)
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 (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 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 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 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
The Control & Monitoring/Power Supply
module uses the IF Processor module for
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.
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.
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
When Auto ALC is selected, the IF level control circuit will
automatically increase the IF output until the desired output
power is attained.
Table 2-7. IF Processor Front Panel Status Indicators
LED
INPUT FAULT (Red)
ALC Fault (Red)
MUTE (Red)
FUNCTION
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.
Table 2-8. IF Processor Front Panel Control Adjustments
POTENTIOMETERS
FREQUENCY
RESPONSE
EQUALIZER
ALC GAIN
MAN GAIN
LINEARITY
CORRECTION
DESCRIPTION
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.
Table 2-9. IF Processor Front Panel Sample
SMA CONNECTOR
IF SAMPLE
LX Series, Rev. 0
DESCRIPTION
Sample of the pre-corrected IF output of the IF Processor
2-4
UHF Analog Driver/Transmitter
Chapter 2, System Description
& Remote Control Connections
2.1.3 (A5) LO/Upconverter Module
Assembly (Appendix B)
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 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.
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.
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.
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
AGC #2 is provided by each of the
optional external amplifier modules.
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.
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.
Example:
For a Frequency RF Out = 517.125 MHz,
N = 517125 kHz / 5 kHz = 103425
The RF output of the LO/Upconverter
Module is at J23 on the rear chassis.
Table 2-10. LO/Upconverter Front Panel Switch
SWITCH
MAN/AUTO AGC
FUNCTION
When Manual AGC is selected, the reference AGC voltage is
set by the AGC Manual Gain front panel potentiometer.
When Auto AGC is selected, the RF power level control circuit
will automatically increase the RF output until the desired
output power is attained.
Table 2-11. LO/Upconverter Front Panel Status Indicator
LED
AGC CUTBACK
(Red)
FUNCTION
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%
Table 2-12. LO/Upconverter Front Panel Control Adjustments
POTENTIOMETERS
MAN GAIN ADJ
AGC CUTBACK ADJ
(AGC OVERRIDE)
DESCRIPTION
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.
Table 2-13. LO/Upconverter Front Panel Samples
SMA CONNECTOR
LO SAMPLE
RF SAMPLE
LX Series, Rev. 0
DESCRIPTION
Sample of the LO signal to the Upconverter as generated by the
UHF Generator Board.
Sample of the On Channel RF Output of the Upconverter
2-6
UHF Analog Driver/Transmitter
Chapter 2, System Description
& Remote Control Connections
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.
2.1.4 (A4) Control/Power Supply
Module Assembly (110 VAC, or 220
VAC, Appendix B)
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.
8A
4A
Table 2-14. Controller/Power Supply Display
DISPLAY
LCD
FUNCTION
A 4 x 20 display providing a four-line readout of the internal
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
OPERATE
(green)
FAULT
(red or green)
DC OK
( red or green )
FUNCTION
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
DISPLAY CONTRAST
LX Series, Rev. 0
DESCRIPTION
Adjusts the contrast of the display for desired viewing of screen.
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)
panel adjustment potentiometers are
used to calibrate the following:
Table 1: Power Amplifier Calibration
Adjustments in Analog Systems
R201
R202
R203
R204
R205
NOTE: The (A6) Power Amplifier Module
Assembly is used in the 10-100 Watt
Transmitter.
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.
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.
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.
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.
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 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 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
The RF power detector circuit outputs
vary with operating frequency. These
circuits must be calibrated at their
intended operating frequency. Front
LX Series, Rev. 0
Reflected Power Cal
Visual / Forward Power Cal
Aural Power Cal
Visual Offset Zero
Aural Null
2-8
UHF Analog Driver/Transmitter
Chapter 2, System Description
& Remote Control Connections
detected, the Upconverter module
reduces its RF output level. For values
less than 0.9 VDC, the Upconverter uses
this voltage for automatic gain.
Table 2-17. Power Amplifier Status Indicator
LED
ENABLED
(Green)
DC OK
(Green)
TEMP
(Green)
MOD OK
(Green)
FUNCTION
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.
Table 2-18. Power Amplifier Control Adjustments
POTENTIOMETERS
RFL CAL
VISUAL CAL
AURAL CAL
VISUAL ZERO
AURAL NULL
DESCRIPTION
Adjusts the gain of the Reflected Power monitoring circuit
Adjusts the gain of the Visual / Forward Power monitoring circuit
Adjusts the gain of the Aural Power monitoring circuit
Adjusts the offset of the Forward Power monitoring circuit
Adjusts the offset of the Forward Power monitoring circuit based on
the Aural signal level.
Table 2-19. Power Amplifier Sample
DISPLAY
FWD SAMPLE
FUNCTION
RF sample of the amplified signal being sent out the module on J25.
2.1.6 RF Output Assemblies
frequencies. Located on the output of
the trap filter is a BNC output sample
jack that can be used for test purposes.
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.
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
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
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
2-9
UHF Analog Driver/Transmitter
and display of the operating parameters
of the transmitter.
Chapter 2, System Description
& Remote Control Connections
This transmitter is either operating or in
standby mode. The sections below
discuss the characteristics of each of
these modes.
2.3 System Operation
Operate Mode
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.
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.
•
•
•
•
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.
2.3.1 Principles of Operation
Operating Modes
LX Series, Rev. 0
Upconverter is unlocked
Upconverter module is not present
IF Processor module is not present
Modulator (if present) is in
Aural/Visual Mute
There are several fault or interlock
conditions that may exist in the
transmitter that will prevent the
2-10
UHF Analog Driver/Transmitter
Chapter 2, System Description
& Remote Control Connections
transmitter from entering the operate
mode. These conditions are:
•
Power Amplifier heat sink
temperature greater than 78°C.
•
Transmitter is Muted due to
conditions listed above.
LX Series, Rev. 0
2-11
UHF Analog Driver/Transmitter
•
Chapter 2, System Description
& Remote Control Connections
•
Power Amplifier Interlock is high
indicating that the amplifier is not
installed.
Receipt of a “Standby CMD” over the
serial interface.
Operating Frequency
Standby Mode
The LX Series transmitter controller is
designed to operate on UHF frequencies.
The exact output frequency of the
transmitter can be set to one of the
standard UHF frequencies, or it can be
set to a custom frequency using
software set-up menus. Since RF
performance of the transmitter requires
different hardware for different
frequency bands, not all frequency
configurations are valid for a specific
transmitter. The Power detectors in the
transmitter have frequency dependency,
therefore detectors of power amplifiers
are calibrated at their frequency of use.
The detectors for System RF monitoring
are also calibrated at the desired
frequency of use.
The standby mode in the transmitter
indicates that the output amplifier of the
transmitter is disabled.
Entering Standby Mode
Similar to the operate mode, the
standby mode is entered using various
means. These are:
•
A low on the Remote Transmitter
Stand-By line.
•
Depressing the “STB” key on
selected front panel menus.
Table 2-23: UHF Television Frequencies
CH
CH
FREQUENCY
FREQUENCY
14
470-476 MHz 38
614-620 MHz
15
476-482 MHz 39
620-626 MHz
16
482-488 MHz 40
626-632 MHz
17
488-494 MHz 41
632-638 MHz
18
494-500 MHz 42
638-644 MHz
19
500-506 MHz 43
644-650 MHz
20
506-512 MHz 44
650-656 MHz
21
512-518 MHz 45
656-662 MHz
22
518-524 MHz 46
662-668 MHz
23
524-530 MHz 47
668-674 MHz
24
530-536 MHz 48
674-680 MHz
25
536-542 MHz 49
680-686 MHz
26
542-548 MHz 50
686-692 MHz
27
548-554 MHz 51
692-698 MHz
28
554-560 MHz 52
698-704 MHz
29
560-566 MHz 53
704-710 MHz
30
566-572 MHz 54
710-716 MHz
31
572-578 MHz 55
716-722 MHz
32
578-584 MHz 56
722-728 MHz
33
584-590 MHz 57
728-734 MHz
34
590-596 MHz 58
734-740 MHz
35
596-602 MHz 59
740-746 MHz
36
602-608 MHz 60
746-752 MHz
37
608-614 MHz
LX Series, Rev. 0
CH
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
2-12
FREQUENCY
752-758
758-764
764-770
770-776
776-782
782-788
788-794
794-800
800-806
806-812
812-818
818-824
824-830
830-836
836-842
842-848
848-854
854-860
860-866
866-872
872-878
878-884
884-890
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
UHF Analog Driver/Transmitter
Chapter 2, System Description
& Remote Control Connections
2.4 Customer Remote Connections
The remote monitoring and operation of
the transmitter is provided through jacks
TB30 and TB31 located on the rear of the
chassis assembly. If remote connections
are made to the transmitter, they must
be made through plugs TB30 and TB31
at positions noted on the transmitter
interconnect drawing and Table 2-20.
Table 2-24: LX Series Chassis Assembly Hard Wired Remote Interface Connections to
TB30 or TB31, 18 pos. Terminal Blocks Located on the Rear of the Assembly
Signal Name
Pin
Designations
RMT Transmitter
State
TB30-1
RMT Transmitter
Interlock
TB30-2
RMT Transmitter
Interlock
Isolated Return
TB30-3
RMT AUX IO 1
TB30-4
RMT AUX IO 2
TB30-5
RMT
Transmitter
Operate
TB30-6
LX Series, Rev. 0
Signal Type/Description
Discrete Open Collector Output - A low indicates that the
transmitter is in the operate mode.
Discrete Open Collector Output - A low indicated the
transmitter is OK or completes a interlock daisy chain.
When the transmitter is not faulted, the interlock circuit
is completed.
Ground - Configurable ground return which can be either
jumpered directly to ground or it can be the “source” pin
of an FET so that the transmitter interlock can be daisy
chained with other transmitters. This signal does not
directly interface to the microcontroller.
Discrete Open Collector Inputs, Discrete Open Drain
Outputs, or 0 - 5 VDC Analog Input - When used as an
output, this line is pulled to +5 VDC with a 1.0 kO
resistor for logic high and pulled to ground for a low. A
diode allows this line to be pulled up to 12 VDC. When
used as a digital input, this line considers all values over
2 Volts as high and those under 1 volt as low. As an
analog input, this line is protected by a 5.1 zener diode.
Discrete Open Collector Input - A pull down to ground on
this line indicates that the transmitter is to be placed into
the operate mode.
2-13
UHF Analog Driver/Transmitter
Signal Name
Pin
Designations
RMT
Transmitter
Stand-By
TB30-7
RMT Power
Raise
TB30-8
RMT Power
Lower
TB30-9
RMT
System Reflect
Power
TB30-10
RMT System
Visual/Forward
Power
TB30-11
RMT
System Aural
Power
TB30-12
RMT Spare 1
RMT Spare 2
TB30-13
TB30-14
System Reflect
Power
TB31-13
System Visual /
Forward Power
TB31-14
System Aural
Power
TB31-15
IF Processor
IF Signal Select
TB31-3
IF Processor
DLC Voltage
TB31-4
UC AGC #2
Voltage
TB31-5
RMT Ground
RMT Ground
LX Series, Rev. 0
TB30-15, and
17
TB31-1, 2, 6
to 12, and 17
Chapter 2, System Description
& Remote Control Connections
Signal Type/Description
Discrete Open Collector Input - A pull down to ground on
this line indicates that the transmitter is to be placed into
the standby mode.
Discrete Open Collector Input - A pull down to ground on
this line indicates that the transmitter power is to be
raised.
Discrete Open Collector Input - A pull down to ground on
this line indicates that the transmitter power is to be
lowered.
Analog Output - 0 to 4.0 V- This is a buffered loop
through of the calibrated “System Reflected Power ” and
indicates the transmitter's reflected output power. The
scale factor is 25%/3.2V.
Analog Output - 0 to 4.0 V- This is a buffered loop
through of the calibrated “System Visual/Avg. Power ”.
Indicates the transmitter's Visual / Average power. Scale
factor is 100%/3.2V.
Analog Output - 0 to 4.0 V- This is a buffered loop
through of the calibrated “System Aural Power ”.
Indicates the transmitter's forward Aural output power.
The scale factor is 100%/3.2V.
Remote connection to spare module - Use is TBD.
Remote connection to spare module - Use is TBD.
Analog Input - 0 to 1.00 V- This is the input of the
“System Reflected Power ” indicating the transmitter's
reflected output power. The scale factor is 25%/0.80V.
Analog Input - 0 to 1.00 V- This is the input of the
“System Visual / Forward Power ” indicating the
transmitter's forward Visual / Forward output power. The
scale factor is 100%/0.80V.
Analog Input - 0 to 1.00 V- This is the input of the
“System Aural Power ” indicating the transmitter's
forward Aural output power. The scale factor is
100%/0.80V.
Discrete Open Collector Input - A low indicates that the
modulator IF source is to be used by the IF Processor
module. When floating an analog IP Processor module
may use the Modulated IF Input if the IF Processor sled
is so configured.
Analog Output - 0 to 5.00 V- This is the input of IF
Processor module for digital system RF output power
control.
Auxiliary Analog Input - 0 to 1V- This voltage is used by
the Upconverter for gain control. Linear signal with
display resolution of 0.01 %. Primary signal source is
J34-1.
Ground pins available through Remote
Ground pins available through Remote
2-14
UHF Analog Driver/Transmitter
Signal Name
RMT +12 VDC
RMT -12 VDC
LX Series, Rev. 0
Pin
Designations
TB30-16
TB31-16
TB30-18
TB31-18
Chapter 2, System Description
& Remote Control Connections
Signal Type/Description
+12 VDC available through Remote w/ 2 Amp re-settable
fuse
-12 VDC available through Remote w/ 2 Amp re-settable
fuse
2-15
UHF Analog Driver/Transmitter
Chapter 3, Site Considerations,
Installation and Setup Procedures
Chapter 3
Site Considerations, Installation and Setup Procedures
There are special considerations that
need to be taken into account before the
Innovator LX Series analog
driver/transmitter can be installed. For
example, if the installation is completed
during cool weather, a heat-related
problem may not surface for many
months, suddenly appearing during the
heat of summer. This section provides
planning information for the installation
and set up of the driver/transmitter.
40° F to 70° F throughout the year,
reasonably low humidity, and a dust-free
room. It should be noted that this is
rarely if ever attainable in the real world.
However, the closer the environment is
to this design, the greater the operating
capacity of the transmitter.
The fans are designed and built into the
transmitter will remove the heat from
within the modules, but additional means
are required for removing this heat from
the building. To achieve this, a few issues
need to be resolved. The first step is to
determine the amount of heat to be
removed from the transmitter room.
There are generally three sources of heat
that must be considered. The first and
most obvious is the heat from the
transmitter itself. This amount can be
determined for a 100W transmitter by
subtracting the average power to the
antenna (69.5 watts) from the AC input
power (675 watts) and taking this
number in watts (605.5) and then
multiplying it by 3.41. This gives a result
of 2,065, the BTUs to be removed every
hour. 12,000 BTUs per hour equals one
ton. Therefore, a 1/4-ton air conditioner
will cool a 100W transmitter.
3.1 Site Considerations
The transmitter requires an AC input line
of 117 VAC/220 VAC @ 5 amps for the
10W transmitter and driver or 117
VAC/220 VAC @ 10 amps for the 100W
Transmitter. The transmitter is factory
set for 110 VAC or 230 VAC operation.
The LX Series Analog Transmitters are
designed and built to provide long life
with a minimum of maintenance. The
environment in which they are placed is
important and certain precautions must
be taken. The three greatest dangers to
the transmitter are heat, dirt, and
moisture. Heat is usually the greatest
problem, followed by dirt, and then
moisture. Over-temperature can cause
heat-related problems such as thermal
runaway and component failure. Each
amplifier module in the transmitter
contains a thermal interlock protection
circuit that will shut down that module
until the temperature drops to an
acceptable level.
The second source of heat is other
equipment in the same room. This
number is calculated in the same way as
the equation for BTUs. The third source
of heat is equally obvious but not as
simple to calculate. This is the heat
coming through the walls, roof, and
windows on a hot summer day. Unless
the underside is exposed, the floor is
usually not a problem. Determining this
number is usually best left up to a
qualified HVAC technician. There are far
too many variables to even estimate this
number without reviewing the detailed
drawings of the site that show all of the
construction details. The sum of these
three sources is the bulk of the heat that
must be removed. There may be other
A suitable environment for the
transmitter can enhance the overall
performance and reliability of the
transmitter and maximize revenues by
minimizing downtime. A properly
designed facility will have an adequate
supply of cool, clean air, free of airborne
particulates of any kind, and no
excessive humidity. An ideal environment
will require temperature in the range of
LX Series, Rev. 0
3-1
UHF Analog Driver/Transmitter
Chapter 3, Site Considerations,
Installation and Setup Procedures
sources of heat, such as personnel, and
all should be taken into account.
Now that the amount of heat that must
be removed is known, the next step is to
determine how to accomplish this. The
options are air conditioning, ventilation,
or a combination of the two. Air
conditioning is always the preferred
method and is the only way to create
anything close to an ideal environment.
Ventilation will work quite well if the
ambient air temperature is below 100° F,
or about 38° C, and the humidity is kept
at a reasonable level. In addition, the air
stream must be adequately filtered to
ensure that no airborne particulates of
any kind will be carried into the
transmitter. The combination of air
conditioning for summer and ventilation
during the cooler months is acceptable
when the proper cooling cannot be
obtained through the use of ventilation
alone and using air conditioning
throughout the year is not feasible.
Caution: The use of air conditioning
and ventilation simultaneously is not
recommended. This can cause
condensation in the transmitters.
2.
Do not have the air conditioner
blowing directly onto the
transmitter. Under certain
conditions, condensation may
occur on, or worse in, the
transmitter.
3.
Do not separate the front of the
transmitter from the back with the
thought of air conditioning only
the front of the unit. Cooling air is
drawn in at the front of all
transmitters and in the front and
back of others. Any attempt to
separate the front of the
transmitter from the rear of the
unit will adversely affect the flow
of cooling air.
4.
Interlocking the transmitter with
the air conditioner is
recommended to keep the
transmitter from operating without
the necessary cooling.
5.
The periodic cleaning of all filters
is a must.
When using ventilation alone, the
following general statements apply:
1.
The blower, with attendant filters,
should be on the inlet, thereby
pressurizing the room and
preventing dirt from entering the
transmitter.
2.
The inlet and outlet vents should
be on the same side of the
building, preferably the leeward
side. As a result, the pressure
differential created by wind will be
minimized. Only the outlet vent
may be released through the roof.
3.
The inlet and outlet vents should
be screened with 1/8-inch
hardware cloth (preferred) or
galvanized hardware cloth
(acceptable).
4.
Cooling air should enter the room
as low as practical but in no case
The following precautions should be
observed regarding air conditioning
systems:
1.
Air conditioners have an ARI
nominal cooling capacity rating. In
selecting an air conditioner, do not
assume that this number can be
equated to the requirements of
the site. Make certain that the
contractor uses the actual
conditions that are to be
maintained at the site in
determining the size of the air
conditioning unit. With the desired
conditioned room temperature
under 80° F, the unit must be
derated, possibly by a substantial
amount.
LX Series, Rev. 0
3-2
UHF Analog Driver/Transmitter
Chapter 3, Site Considerations,
Installation and Setup Procedures
higher than four feet above the
floor. The inlet must be located
where dirt, leaves, snow, etc., will
not be carried in with the cooling
air.
5.
The exhaust should be located as
high as possible. Some ducting is
usually required to insure the
complete flushing of heated air
with no stagnant areas.
6.
The filter area must be large
enough to insure a maximum air
velocity of 300 feet per minute
through the filter. This is not a
conservative number but a neverexceed number. In a dusty or
remote location, this number
should be reduced to 150 CFM.
7.
The inlet and outlet(s) must have
automatic dampers that close any
time the ventilation blower is off.
8.
9.
10.
In those cases in which
transmitters are regularly off for a
portion of each day, a
temperature-differential sensor
that controls a small heater must
be installed. This sensor will
monitor inside and outside
temperatures simultaneously. If
the inside temperature falls to
within 5° F of the outside
temperature, the heater will come
on. This will prevent condensation
when the ventilation blower comes
on and should be used even in the
summer.
The blower on high speed must be
capable of moving the required
volume of air into a half inch of
water pressure at the required
elevation. The free air delivery
method must not be used.
12.
Regular maintenance of the filters,
if used, can not be
overemphasized.
13.
Above 4000 feet, for external
venting, the air vent on the
cabinet top must be increased to
an 8-inch diameter for a 1-kW
transmitter and to a 10-inch
diameter for 5-kW and 6-kW
transmitters. An equivalent
rectangular duct may be used but,
in all cases, the outlet must be
increased by 50% through the
outlet screen.
14.
It is recommended that a site plan
be submitted to Axcera for
comments before installation
begins.
In calculating the blower requirements,
filter size, and exhaust size, if the total
load is known in watts, 2000 CFM into ½
inch of water will be required for each
5000 watts. If the load is known in BTUs,
2000 CFM into ½ inch of water will be
required for each 17,000 BTUs. The inlet
filter must be a minimum of seven
square feet, larger for dusty and remote
locations, for each 5000 watts or 17,000
BTUs. The exhaust must be at least four
square feet at the exhaust screen for
each 5000 watts or 17,000 BTUs.
A controlled-air bypass system
must be installed to prevent the
temperature in the room from
falling below 40° F during
transmitter operation.
The information presented in this section
is intended to serve only as a general
guide and may need to be modified for
unusually severe conditions. A
combination of air conditioning and
ventilation should not be difficult to
design (see Figure 3-1).
The blower should have two
speeds, which are thermostatically
controlled, and be interlocked with
the transmitter.
LX Series, Rev. 0
11.
System interlocking and thermostat
settings should be reviewed with Axcera.
As with any equipment installation, it is
3-3
UHF Analog Driver/Transmitter
Chapter 3, Site Considerations,
Installation and Setup Procedures
always good practice to consult the
manufacturer when questions arise.
Axcera can be contacted at (724) 8738100.
Figure 3-1. 1 kW Minimum Ventilation Configuration
3.2 Unpacking the Chassis
w/modules, bandpass and trap
filters
The modules are mounted to the chassis
assembly with slides that are on the top
and the bottom of the modules. There
are two thumb screws on the front panel
that hold each of the modules in place.
Thoroughly inspect the chassis with
modules and all other materials upon
their arrival. Axcera certifies that upon
leaving our facility the equipment was
undamaged and in proper working order.
The shipping containers should be
inspected for obvious damage that
indicates rough handling.
3.3 Installing the Chassis w/modules
and filters
The chassis assembly is made to mount
in a standard 19” rack. The chassis
assembly mounts using the four #10
clearance mounting holes on the ends.
The chassis should be positioned; to
provide adequate air intake into the front
and the air exhaust of the fan in the rear;
the ability to slide the modules out for
replacement purposes; the installation of
the bandpass filter and trap filter; the
coupler assembly; and output
transmission line. The chassis or cabinet
in which it is mounted should be
grounded using copper strapping
material.
Remove the chassis and modules, along
with bandpass filter and trap Filter, from
the crates and boxes.
Check for dents and scratches or broken
connectors, switches, display, or
connectors. Any claims against in-transit
damage should be directed to the carrier.
Inform Axcera as to the extent of any
damage as soon as possible.
LX Series, Rev. 0
3-4
UHF Analog Driver/Transmitter
Chapter 3, Site Considerations,
Installation and Setup Procedures
NOTE: To pull out the power amplifier
module for replacement purposes, the
input and output coaxial cables must first
be removed from the rear of the chassis
assembly.
Connect the bandpass filter and trap filter
to the output of the chassis assembly.
Figure 3-2. Front and Rear View Reconnection Drawing
Connect the transmission line for the
antenna system to the output of the trap
filter. A BNC sample jack of the output
on the trap filter can be used for test
purpose.
This completes the unpacking and
installation of the LX Series UHF
television transmitter. Refer to the setup
and operation procedures that follow
before applying power to the transmitter.
3.4 AC Input
3.5 Setup and Operation
The Exciter/Amplifier chassis assembly
needs an AC outlet in which to plug, of
115 or 230 VAC, as set at the factory, at
5 amps for the 10W and driver or 10
amps for the 100W transmitter.
Initially, the transmitter should be turned
on with the RF output at the Trap Filter
terminated into a dummy load of 10W or
100W depending on the power rating of
the transmitter. If a load is not available,
check that the output of the trap filter is
connected to the antenna for your
system.
When the AC power cord for the
exciter/amplifier chassis is plugged in,
the AC is always connected to the
transmitter.
3.5.1 Input Connections
The input connections to the transmitter
are to the rear of the Chassis Assembly
for the transmitter or to the receiver tray
in a translator.
Once the chassis and output connections
are in place, the AC cord from the chassis
can plug into an AC outlet, 110 or 220
VAC as configured at the factory, of 5
Amps for the 10W transmitter and driver
or 10 Amps for the 100W transmitter.
LX Series, Rev. 0
Refer to the tables and description that
follows for detailed information on the
input connections.
3-5
UHF Analog Driver/Transmitter
Chapter 3, Site Considerations,
Installation and Setup Procedures
Figure 3-3: Rear View of LX Series Analog Transmitter
J25
J21
TB02
TB30
J18
TB31
J9
J6
J24
J11
J4
J8
J23
J19
J32
J5
J34
Table 3-1: Rear Chassis Connections for the LX Series Analog Transmitter.
Port
J1
TB02
J3
J4
J5
J6
J7
J8
J9
J10
J11
Type
IEC
Term
BNC
BNC
BNC
BNC
BNC
BNC
BNC
BNC
BNC
Function
AC Input
Base Band Audio Input
Composite Audio Input
SAP / PRO Audio Input
CW IF Input
Modulated IF Input
Video Input (Isolated)
Visual IF Loop-Thru Output
Aural IF Loop-Thru Output
10 MHz Reference Input
10 MHz Reference Output
Ohm
J17
J18
J19
BNC
BNC
BNC
Video Loop-Thru (Isolated)
Visual IF Loop-Thru Input
Aural IF Loop-Thru Input
75
50
50
J23
J24
J25
BNC
BNC
Upconverter RF Output
Power Amplifier RF Input
Power Amplifier RF Output
50
50
50
Term
Term
RJ-45
RJ-45
RJ-45
Remote Control
Remote Control
SCADA (Input /
SCADA (Input /
System RS-485
TB30
TB31
J32
J33
J34
LX Series, Rev. 0
& Monitoring
& Monitoring
Loop-Thru)
Loop-Thru)
Serial
3-6
J7
J17
J10
J33
J1
J3
600
75
50
50
50
75
50
50
50
50
CAT5
CAT5
CAT5
UHF Analog Driver/Transmitter
Chapter 3, Site Considerations,
Installation and Setup Procedures
3.5.2 Front Panel Screens for the
Exciter/Amplifier Chassis Assembly
characters are special characters used to
navigate up or down through the menu
screens. Display text flashes on discrete
fault conditions for all screens that
display a fault condition.
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
and display of the operating parameters
of the transmitter. Below are the display
screens for the system. The ↑ and ↓
When the transmitter is in operate mode,
the STB menu appears. When the
transmitter is in standby mode, the OPR
menu appears.
Display Menu Screens for the LX Series Transmitter
Table 3-2: Menu 01 - Splash Screen #1
C E
W R
2 4
P A
8 1
This is the first of the two transmitter splash screens that is shown for the first few
seconds after reset.
Table 3-3: Menu 02- Splash Screen #2
N E E
M W A
D A
This is the second of the two transmitter splash screens
Table 3-4: Menu 10 - Main Screen
↑
↓
P W R
W R
E D
W R
This is the default main screen of the transmitter. When the transmitter is in operate,
the 'STB' characters appear allowing an operator to place the transmitter in STAND-BY.
When the transmitter is in standby the 'STB' characters are replaced with 'OPR' and an
operator can place the transmitter into OPERATE by pressing the right most switch on the
front panel display. If the ↓ key is activated the system changes to Menu 11, go to Menu
11. If the ↑ key is activated the system displays to Menu 13, go to Menu 13.
LX Series, Rev. 0
3-7
UHF Analog Driver/Transmitter
Chapter 3, Site Considerations,
Installation and Setup Procedures
Table 3-5: Menu 11 - Error List Access Screen
↑
↓
This screen of the transmitter shows the current number of errors and provides operator
access to view the error list. This is the entry point to Menu 20. If ENT is pushed, go to
Menu 20. If the ↓ key is activated the system changes to Menu 12, go to Menu 12. If the
↑ key is activated the system returns to Menu 10, go to Menu 10.
Table 3-6: Menu 12 - Transmitter Device Data Access Screen
↑
M I
↓
This screen of the transmitter allows access to various parameters of the transmitter
system. This is the entry point to Menu 30. If ENT is pushed, go to Menu 30. If the ↓
key is activated the system changes to Menu 13, go to Menu 13. If the ↑ key is activated
the system returns to Menu 11, go to Menu 11.
Table 3-7: Menu 13 - Transmitter Configuration Access Screen
↑
M I
↓
This screen of the transmitter allows access to various software setting of the transmitter
system. This is the entry point to Menu 40. If ENT is pushed, go to Menu 40. If the ↓
key is activated the system returns to Menu 10, go to Menu 10. If the ↑ key is activated
the system returns to Menu 12, go to Menu 12.
Table 3-8: Menu 20 - Error List Display Screen
↑
V E
L O
↓
M O
U L
This screen of the transmitter allows access to system faults. Fault logging is stored in
non-volatile memory. The transmitter's operating state can not be changed in this
screen. The 'CLR' switch is used to clear previously detected faults that are no longer
active. The ↑ key and ↓ key allow an operator to scroll through the list of system errors
that have occurred. The ESC switch is used to leave this screen.
LX Series, Rev. 0
3-8
UHF Analog Driver/Transmitter
Chapter 3, Site Considerations,
Installation and Setup Procedures
Table 3-9: Menu 30 - Transmitter Device Details Screen
Y S T
M T R
O W E
↑
I N
↓
M O
This screen of the transmitter allows access to the transmitter parameters of installed
devices. The system is configured to know which devices are present. Current values for
all installed devices are shown. If a module is not installed, only a "MODULE NOT
PRESENT" message will be displayed. The ↑ and ↓ arrows scroll through the different
parameters of each device as shown in table 3-11. Each System Component is a
different screen. One IF Processor or the other will be programmed for your system. One
Power Amplifier or the other will be programmed for your system. External Amplifier will
only be used in high power transmitters.
Table 3-10: Menu 30-1 – System Details Screen
↑
↓
Table 3-11: Transmitter Device Parameters Detail Screens
System Component
Parameter
Normal
Faulted (Blinking)
Modulator Details
PLL CIRCUIT
OUTPUT LEVEL
AURAL DEVIATION
CW INPUT
STATION ID
LOCKED
0 - 200 IRE
0 - 125 kHz
PRESENT
SEND soft key
UNLOCKED
N/A
N/A
NOT USED
N/A
IF Processor Details
(Analog Systems)
INPUT SIGNAL
STATE
MODULATION
INPUT IF
DLC LEVEL
ALC LEVEL
ALC MODE
OK
OK
MODULATOR or J6
0 - 5.00 V
0 - 5.00 V
AUTO or MANUAL
FAULT
FAULT
N/A
N/A
N/A
N/A
(OR)
IF Processor Details
(Digital Systems)
ALC LEVEL
ALC MODE
DLC LEVEL
0 - 5.00 V
AUTO or MANUAL
0 - 5.00 V
N/A
N/A
N/A
PLL CIRCUIT
AFC LEVEL
AGC 1 LEVEL
AGC 2 LEVEL
FAULT
N/A
N/A
N/A
EX. 10 MHz
LO FREQ
LOCKED
0 - 5.00 V
0 - 5.00 V
0 - 5.00 V
PRESENT or NOT
USED
xxx.xxx MHz
POWER SUPPLY
STATE
±12V SUPPLY
ON or OFF
OK or OFF
N/A
FAULT
Upconverter Details
Driver and PA
Details
LX Series, Rev. 0
3-9
N/A
N/A
UHF Analog Driver/Transmitter
System Component
Chapter 3, Site Considerations,
Installation and Setup Procedures
Parameter
Ext. Power Amplifier
Modules Details
(Only in high power
systems)
Normal
Faulted (Blinking)
FORWARD POWER
REFLECTED POWER
AMP 1 CURRENT
AMP 2 CURRENT
TEMPERATURE
CODE VERSION
xxx%
xxx%
xx.xA
xx.xA
xxC
x.x
xxx%
xxx%
xx.xA
xx.xA
xxC
N/A
POWER SUPPLY
STATE
±12V SUPPLY
FORWARD POWER
REFLECTED POWER
AMP CURRENT 1
AMP CURRENT 2
AMP CURRENT 3
AMP TEMPERATURE
CODE VERSION
ON or OFF
OK or OFF
xxx%
xxx%
xx.xA
xx.xA
xx.xA
xxC
x.x
N/A
FAULT
xxx%
xxx%
xx.xA
xx.xA
xx.xA
xxC
N/A
Table 3-12: Menu 40 - Transmitter Set-up: Power Raise/Lower Screen
↑
M I
W E
T T
↓
E R
R A
+ )
U P
O W E
( -
This screen of the transmitter is the first of several that allows access to transmitter setup parameters. When + is selected, the Power will increase. When - is selected, the
Power will decrease.
Table 3-13: Menu 40-1 - Transmitter Set-up: Model Select Screen
↑
M I
A N
M B
↓
T E R
M I T
( + )
- U
M O
0 0
This screen is used to specify which components are expected to be part of the system.
By specifying the model number, the transmitter control firmware knows which
components should be installed and it will be able to display faults for components that
are not properly responding to system commands.
LX Series, Rev. 0
3-10
UHF Analog Driver/Transmitter
Chapter 3, Site Considerations,
Installation and Setup Procedures
Table 3-14: Menu 40-2 - Transmitter Set-up: Frequency Select Screen
↑
M I
E Q
B L
↓
C T
( -
This screen of the transmitter is allows access to transmitter frequency set-up
parameters. The choices of this screen are 'TABLE' or 'CUSTOM'. When table is selected,
the next menu will be used to select the desired operating frequency. When custom is
selected, the next menu is used to select a specific operating frequency.
Table 3-15: Menu 40-3 - Transmitter Set-up: Frequency Table Select Screen
↑
M I
E Q
↓
C T
M H
( -
The choices of this screen are from the standard UHF / VHF tables. + and - change the
desired value of the transmitter. Any change to frequency is immediately set to the LO /
Upconverter Frequency Synthesizer PLL circuit.
Table 3-16: Menu 40-4 - Transmitter Set-up: IF Frequency Screen
↑
M I
P U
↓
M H
This screen is used to specify the IF Input frequency. This value plus the desired channel
value is used to calculated the desired LO frequency. + is used to increase the selected
value from 0 to 9. The > key is used to select from each of the different fields that make
up the desired frequency. Any change to frequency is immediately set to the LO /
Upconverter Frequency Synthesizer PLL circuit.
Table 3-17: Menu 40-5 - Transmitter Set-up: Custom Frequency Select Screen
↑
M I
E Q
↓
C T
M H
( -
This screen is used to specify the operating frequency to an exact value. + is used to
increase the selected value from 0 to 9. The > key is used to select from each of the
different fields that make up the desired frequency.
Any change to frequency is
immediately set to the LO / Upconverter Frequency Synthesizer PLL circuit.
LX Series, Rev. 0
3-11
UHF Analog Driver/Transmitter
Chapter 3, Site Considerations,
Installation and Setup Procedures
Table 3-18: Menu 40-6 - Transmitter Set-up: Serial Address Screen
↑
M I
R I
↓
+ )
This screen allows the user to set the serial address of the transmitter. The default
address is 5. This value and all other set-up parameters, are stored in non-volatile
memory.
Table 3-19: Menu 40-7 - Transmitter Set-up: Station ID Screen
N S
M O
S T
↑
M I
D U
A T
↓
E R
T E
+ )
This screen allows the user to set the serial address of the transmitter. The default
address is 5. This value and all other set-up parameters, are stored in non-volatile
memory.
Table 3-20: Menu 40-8 - Transmitter Set-up: System Visual Power Calibration
↑
M I
S T
S U
↓
T E
( +
- )
This screen is used to adjust the calibration of the system's visual power. A symbol
placed under the '6' character is used to show minor changes in the calibration value.
When the calibration value is at full value, the character will be full black. As the value
decreases, the character pixels are gradually turned off.
Table 3-21: Menu 40-9 - Transmitter Set-up: System Aural Power Calibration
↑
M I
S T
R A
↓
T E
( +
C A
W R
- )
This screen is used to adjust the calibration of the system's aural forward power. A
symbol as on the previous screen is under the '6' character on this screen.
LX Series, Rev. 0
3-12
UHF Analog Driver/Transmitter
Chapter 3, Site Considerations,
Installation and Setup Procedures
Table 3-22: Menu 40-10 - Transmitter Set-up: System Reflected Power Calibration
↑
M I
S T
F L
↓
T E R
C T
( + )
- )
This screen is used to adjust the calibration of the system's reflected power.
Table 3-23: Menu 40-11 - Transmitter Set-up: Forward Power Fault Threshold Screen
N S
M I
P O
↑
M I
N I
W E
↓
T T
M U
E R
F A
+ )
T W A
This screen is used to set the minimum forward power fault threshold. When the
transmitter is operating, it must operate above this value otherwise the system will shut
down with fault for 5 minutes. If after five minutes the fault is not fixed, the transmitter
will enable, measure power less than this value and again shut down for five minutes.
Table 3-24: Menu 40-12 - Transmitter Set-up: Reflected Power Fault Threshold
N S
M A
P O
↑
M I
X I
W E
↓
T T
M U
E R
F A
+ )
This screen is used to set the maximum reflected power fault threshold. When the
transmitter is operating, it must not operate above this value otherwise the system will
shut down with fault for 5 minutes. If after five minutes the fault is not fixed, the
transmitter will enable, measure power above this value and again shut down for five
minutes.
Table 3-25: Menu 40-13 - Transmitter Set-up: Remote Commands Control
↑
M I T
M O T
M M A
↓
D S
+ )
This screen is used to allow or deny the use of remote control commands. When
disabled, remote commands are not used. Remote commands are commands received
either through the rear terminal blocks or through serial messages.
This completes the description of the
screens for the LX Series
exciter/amplifier chassis assembly.
If the transmitter is already connected
to the antenna, check that the output is
100%. If necessary, adjust the
LX Series, Rev. 0
amplifier power detection circuitry or
LO / Upconverter AGC settings. The
power raise / lower settings are only to
be used for temporary reductions in
power. The power set-back values do
not directly correspond to the power of
the transmitter. Setting for 50%
3-13
UHF Analog Driver/Transmitter
Chapter 3, Site Considerations,
Installation and Setup Procedures
output sets a linear circuit voltage that
is controlling a non-linear power circuit.
VIDEO LOSS: This indicates the loss of
Video to the modulator, when Red.
If a problem occurred during the setup
and operation procedures, refer to
Chapter 5, Detailed Alignment
Procedures, of this manual for more
information.
OVER MOD: This illuminates Red when
the video is overmodulated.
ALT IF CW: This indicates that there is
an external IF CW signal applied to the
Modulator
3.5.3 Initial Turn On
Once the unit has been installed and
all connections have been made, the
process of turning on the equipment
can begin. First verify that AC power
is present and connected to the
transmitter. Verify all cables are
properly connected and are the correct
type. Once all of these things are
done, the unit is ready to be turned on
following the procedures below.
Turn on the main AC
that
supplies
the
transmitter. Check that
plug is connected to J1
the chassis assembly.
power source
AC
to
the
the AC power
on the rear of
Monitor the LCD display located on the
front of the control/monitoring module
as you proceed through this section.
When the transmitter is in the operate
mode, the STB menu appears. When
in the standby mode, the OPR menu
appears. Press the NXT key after each
menu
to
continue
through
the
sequence.
MODULATOR MODULE LEDs ON
FRONT PANEL
Fault Indicators:
AUR UNLOCK: This illuminates Red
when the Aural IF PLL is unlocked.
VIS UNLOCK: This illuminates RED
when the Visual IF PLL is unlocked.
AUD OV DEV: This indicator will
illuminate Red when the audio overdeviates the aural carrier.
LX Series, Rev. 0
Status Indicators:
10MHz PRES: This indicates the
presence of a 10 MHz reference input.
IF PROCESSOR MODULE LEDs ON
FRONT PANEL
Fault Indicators:
INPUT FAULT: This illuminates Red if
the input to the module is missing or
low.
ALC FAULT: This illuminates RED when
the needed ALC value to maintain the
output level is beyond the range of the
circuitry.
MUTE: This indicator will illuminate
Red when the transmitter is muted.
UPCONVERTER MODULE LED ON
FRONT PANEL
Fault Indicator:
AGC CUTBACK-This illuminates Red if
the required gain to produce the
desired output level is beyond the
value set by the AGC Cutback circuit.
CONTROLLER MODULE LEDs ON
FRONT PANEL
Status Indicators:
OPERATE - This illuminates Green
when transmitter is in operate.
FAULT - This illuminates Red when a
fault has occurred in the transmitter.
3-14
UHF Analog Driver/Transmitter
DC OK - This illuminates Green when
the DC outputs that connect to the
modules in the transmitter are
present.
Chapter 3, Site Considerations,
Installation and Setup Procedures
DC OK - This illuminates Green when
the DC inputs to the PA module are
present.
POWER AMPLIFIER OR DRIVER
MODULE LEDs ON FRONT PANEL
TEMP - This illuminates Green when
the temperature of the heatsink in the
PA is below 78°C.
NOTE: Both the PA Module and Driver
Module have the same front panel
LEDs.
MOD OK - This illuminates Green when
the PA module is operating and has no
faults.
Status Indicators:
This completes the Installation, Set Up
and Turn On of the Driver/Transmitter.
ENABLED - This illuminates Green
when the PA is in operate.
LX Series, Rev. 0
3-15
UHF Analog Driver/Transmitter
Chapter 4, Circuit Descriptions
Chapter 4
Circuit Descriptions
4.1 (A2) Modulator Module; Appendix B)
NOTE: Not used in a translator system.
4.1.1 Analog Modulator Board; Appendix B)
The board takes the audio and video inputs and produces a modulated visual IF + aural IF
output.
Main Audio and Aural IF portion of the board
The analog modulator board takes each of the three possible audio inputs and provides a
single audio output.
4.1.1.1 MONO, Balanced Audio Input
The first of the three possible baseband inputs to the board is a 600-Ω, balanced-audio
input (0 to +10 dBm) that enters through jack J41A, pins 10A (+), 12A (GND), and 11A (), and is buffered by U11A and U11B. Diodes CR9, CR10, CR12 and CR13 protect the input
to U11A and U11B if an excessive signal level is present on the input. The outputs of U11A
and U1B are applied to differential amplifier U11C. U11C eliminates any common mode
signals (hum) on its input leads. A pre-emphasis of 75 ms is provided by R97, C44, and
R98 and can be eliminated by removing jumper W6 on J22. The signal is then applied to
amplifier U11D whose gain is controlled by jumper W7 on J23. Jumper W7 on jack J23 is
positioned according to the input level of the audio signal (0 or +10 dBm). If the input
level is approximately 0 dBm, the mini-jumper should be in the high gain position between
pins 1 and 2 of jack J23. If the input level is approximately +10 dBm, the mini-jumper
should be in low gain position between pins 2 and 3 of jack J23. The balanced audio is
then connected to buffer amplifier U12A whose input level is determined by the setting of
the MONO, balanced audio gain pot R110, accessed through the front panel. The output
of the amplifier stage is wired to the summing point at U13C, pin 9.
4.1.1.2 STEREO, Composite Audio Input
The second possible audio input to the board is the composite audio (stereo) input that
connects to the board at J41A Pin 14A (+) and J41A Pin 13A (-).
NOTE: For the transmitter to operate using the composite audio input the Jumper W1 on
J4 must be between Pins 2 and 3, the Jumper W2 on J6 must be between Pins 2 and 3
and the Jumper W4 on J5 must be between Pins 1 and 2. These jumpers connect the
composite audio to the rest of the board.
Jumper W14 on jack J26 provides a 75Ω-input impedance when the jumper is between
pins 1 and 2 and a high impedance when it is between pins 2 and 3. Diodes CR17, CR18,
CR20 and CR21 protect the input stages of U14A and U14B if an excessive signal level is
applied to the board. The outputs of U14A and U14B are applied to differential amplifier
U13A, which eliminates common mode signals (hum) on its input leads. The composite
input signal is then applied to amplifier U13B; whose gain is controlled by the STEREO,
composite audio gain pot R132, accessed through the front panel. The composite audio
signal is then connected to the summing point at U13C, pin 9.
LX Series, Rev. 0
4-1
UHF Analog Driver/Transmitter
Chapter 4, Circuit Descriptions
4.1.1.3 SAP/PRO, Subcarrier Audio Input
The third possible input to the board is the SAP/PRO, SCA audio input at J41A pin 16A(+)
and 17A(-). The SCA input has an input matching impedance of 75Ω that can be
eliminated by removing jumper W15 from pins 1 and 2 of J28. The SCA input is bandpass
filtered by C73, C74, R145, C78, C79, and R146 and is fed to buffer amplifier U13D. The
amplified signal is then applied though the SAP/PRO, SCA gain pot R150, accessed
through the front panel, to the summing point at pin 9 of U13C.
4.1.1.4 Audio Modulation of the
4.5 MHz VCO
The Mono balanced audio, or the Stereo composite audio, or the SAP/PRO SCA buffered
audio signal, is fed to the common junction of resistors R111, R130, and R152 that
connect to pin 9 of amplifier U13C. The output audio signal at pin 8 of U13C is typically .8
Vpk-pk at a ±25-kHz deviation for Mono balanced audio or .8 Vpk-pk at ±75-kHz
deviation for Stereo composite audio as measured at Test Point TP1. This audio deviation
signal is applied to the circuits containing the 4.5 MHz aural VCO U16. A sample of the
aural deviation level is amplified, detected by U15A and U15B, and connected to J41A pin
5A on the board. This audio-deviation level is connected to the front panel display on the
Control/Power Supply Assembly.
The audio from U13C is connected thru C71, a frequency response adjustment, to
varactor diodes, CR24 to CR27, that frequency modulates the audio signal onto the
generated 4.5-MHz signal by U16. U16 is the 4.5-MHz VCO that generates the 4.5-MHz
continuous wave (CW) signal. The output frequency of the 4.5 MHz signal is maintained
and controlled by the correction voltage output of the U21 PLL integrated circuit (IC), at
“N”, that connects to the varactor diodes. The audio-modulated, 4.5-MHz signal is fed
through the emitter follower Q13 to the amplifiers U17A and U17B. The amplified output
of U17A is connected to a 4.5-MHz filter and then to U17B. The output of U17B is
connected to the 4.5-MHz output sample jack at J29 and through the Jumper W4 on J5
pins 1 & 2, “J”, to the I input of the mixer Z1.
4.1.1.5 Phase Lock Loop (PLL) Circuit
A sample of the signal from the 4.5-MHz aural VCO at the output of Q13, “M”, is applied to
PLL IC U21 at pin 1 the Fin connection. In U21, the signal is divided down to 50 kHz and is
compared to a 50-kHz reference signal. The reference signal is a divided-down sample of
the 45.75-MHz visual IF signal that is applied to the oscillator-in connection at Pin 27 on
the PLL chip. These two 50-kHz signals are compared in the IC and the fV, and fR is
applied to the differential amplifier U18A. The output of U18A, “N”, is fed back through
CR28 and C85 to the 4.5-MHz VCO IC U16; this sets up a PLL circuit. The
4.5-MHz VCO will maintain the extremely accurate 4.5-MHz separation between the visual
and aural IF signals; any change in frequency will be corrected by the AFC error voltage.
PLL chip U21 also contains an internal lock detector that indicates the status of the PLL
circuit. When U21 is in a "locked" state, pin 28 is high. If the 4.5-MHz VCO and the 45.75MHz oscillator become "unlocked," out of the capture range of the PLL circuit, pin 28 of
U21 will go to a logic low and cause the LED DS5 to light red. The Aural Unlock LED is
LX Series, Rev. 0
4-2
UHF Analog Driver/Transmitter
Chapter 4, Circuit Descriptions
viewed through the front panel of the Assembly. An Aural unlock, PLL Unlocked, output
signal from Q16 is also applied to jack J41B pin 1B.
Sync tip clamp and the visual and aural modulator portions of the board
The sync tip clamp and modulator portion of the board is made up of four circuits: the
main video circuit, the sync tip clamp circuit, the visual modulator circuit and the aural
modulator circuit.
The clamp portion of the board maintains a constant peak of sync level over varying
average picture levels (APL). The modulator portion of the board contains the circuitry
that generates an amplitude-modulated vestigial sideband visual IF signal output that is
made up of the baseband video input signal (.5 to 1 Vpk-pk) modulated onto a 45.75-MHz
IF carrier frequency. The visual IF signal and the aural IF signal are then combined in the
diplexer circuit to produce the visual IF + aural IF output, “G”, that is connected to J41C
pin 28C the Combined IF output of the board.
4.1.1.6 Main Video Signal Path
(Part 1 of 2)
The baseband video input connects to the board at J41A pins 19A (-), “W”, and 20A (+),
“V”. The +, “V” and -, “W”, video inputs are fed to Diodes CR1 to CR4 that form a
voltage-limiter network in which, if the input voltages exceed the supply voltages for U2B,
the diodes conduct, preventing damage to U2B. CR1 and CR3 conduct if the input voltage
exceeds the negative supply and CR2 and CR4 conduct if the input voltage exceeds the
positive supply voltage. The baseband video input connects to the non-inverting and
inverting inputs of U2B, a differential amplifier that minimizes any common-mode
problems that may be present on the incoming signal
The video output of U2B is connected through the Video Gain pot R42, accessed through
the front panel, to the amplifier U2A. The output of U2A connects to the delay equalizer
circuits
4.1.1.7 Delay Equalizer Circuits
The delay equalizer circuits provide a delay to the video signal, correction to the frequency
response, and amplification of the video signal.
The video output of U2A is wired to the first of four delay-equalizing circuits that shape the
video signal to the FCC specification for delay equalization or to the shape needed for the
system. The board has been factory-adjusted to this FCC specification and should not be
readjusted without the proper equipment.
Resistors R53, R63, R61, and R58 adjust the sharpness of the response curve while
inductors GD1, GD2, GD3, and GD4 adjust the position of the curve. The group delayed
video signal at the output of U3A is split with a sample connected to J8 on the board that
can be used for testing purposes of the Post Video Delay signal. The other portion of the
video signal connects through the Jumper W5 on J9 pins 2 and 3. The video is slit with
one part connecting to a sync tip clamp circuit and the other part to the main video output
path through R44. A sample of the video at “P” connects to U32 and U33 that provide a
zero adjust and a 1 Volt output level, which connects at “T” to J41A pin 3A. This video
level is wired to the Control/Power Supply assembly.
4.1.1.8 Sync Tip Clamp Circuit
LX Series, Rev. 0
4-3
UHF Analog Driver/Transmitter
Chapter 4, Circuit Descriptions
The automatic sync tip clamp circuit is made up of U6A, Q8, U5C, and associated
components. The circuit begins with a sample of the clamped video that buffered by U3A,
which is split off from the main video path that connects to U6A. The level at which the
tip of sync is clamped, to
-1.04 VDC as set by the voltage-divider network, R77, R78, R75, R76 and R80 connected
to U6A. If the video level changes, the sample applied to U6A changes. The voltage from
the clamp circuit that is applied to the summing circuit at the base of Q8 will change; this
will bring the sync tip level back to
-1.04 VDC. Q8 will be turned off and on according to the peak of sync voltage level that is
applied to U6A. The capacitors C35 and C24, in the output circuit of Q8, will charge or
discharge to the new voltage level. This will bias U5C more or less, through the front
panel MANUAL/AUTO CLAMP switch, SW1, when it is in the Auto Clamp-On position,
between pins 2 and 3. In AUTO CLAMP, U5C will increase or decrease its output, as
needed, to bring the peak of sync back to the correct level. The voltage level is applied
through U5C to U2A. In the Manual CLAMP position, SW1 in manual position, between pins
1 and 2, the adjustable resistor R67 provides the manual clamp bias adjustment for the
video that connects to U5C. This level is set at the factory and is not adjustable by the
customer. In Manual clamp the peak of sync auto clamp circuit will not automatically be
clamped to the pre set level.
4.1.1.9 Main Video Signal Path
(Part 2 of 2)
A sample of the clamped video output from the group delay circuitry at the junction of
R44, R62 and R300 is connected to a white clipper circuit consisting of Q1 and associated
circuitry. The base voltage of Q1 is set by the voltage divider network consisting of R1, R9
and R5. R5 is variable and sets the level of the white clipper circuit to prevent video
transients from over modulating the video carrier.
The clamped video output of amplifier U3A is split with one part connected through R35 to
J8 that provides a sample of the Post Video Delay Signal.
The other clamped video path from U3A is through jumper W5 on J9 pins 2 & 3 through
R44 to a sync-stretch circuit that consists of Q3 and Q4. The sync-stretch circuit contains
R19, which adjusts the Sync Stretch Magnitude (amount), R11, which adjusts the Sync
Stretch Cut-In and R6, which adjusts the Sync Clipping point. This sync-stretch
adjustment should not be used to correct for output sync problems, but it can be used for
video input sync problems. The output of the sync-stretch circuit is amplified by U31A and
connected, “K”, to pin 5, the I input of Mixer Z2, the Visual IF Mixer.
4.1.1 10 45.75 MHz Oven Oscillator
Circuit
The oven oscillator portion of the board generates the visual IF CW signal at 45.75 MHz
for NTSC system "M" usage.
The +12 VDC needed to operate the oven is applied through jack J30 pin 1 on the crystal
oven HR1. The oven is preset to operate at 60° C. The oven encloses the 45.75 MHz
crystal Y1 and stabilizes the crystal temperature. The crystal is the principal device that
determines the operating frequency and is the most sensitive in terms of temperature
stability.
LX Series, Rev. 0
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UHF Analog Driver/Transmitter
Chapter 4, Circuit Descriptions
Crystal Y1 operates in an oscillator circuit consisting of transistor Q24 and its associated
components. Feedback that is provided by a voltage divider, consisting of C173, L38 and
R295, is fed to the base of Q24 through C169. This circuitry operates the crystal in a
common-base amplifier configuration using Q24. The operating frequency of the oscillator
is maintained by a PLL circuit, which consists of ICs U20 and U22 and associated
components, whose PLL output connects to R293 in the crystal circuit.
The oscillator circuit around Q24 has a regulated voltage, +6.8 VDC, which is produced
from the +12 VDC by a combination of dropping resistor R261, diodes CR37 and CR38
and Zener diode VR2. The output of the oscillator at the collector of Q24 is capacitively
coupled through C165 to the base of Q23. The small value of C165, 15 pF, keeps the
oscillator from being loaded down by Q23. Q23 is operated as a common-emitter
amplifier stage whose bias is provided through R259 from the +12 VDC line. The output of
Q23, at its collector, is connected to an emitter-follower transistor stage, Q21. The output
of Q21 at its emitter is split. One path connects to the input of the IC U20 in the PLL
circuit. The other path is through R270 to establish an approximate 50-ohm source
impedance through C166 to the Pin 1 contact of the relay K2. The 45.75 MHz connects
through the closed contacts 0of K2 to a splitter network consisting of L31 and L32.
NOTE: The relay contacts for the internally generated 45.75 MHz signal will be closed
unless an external IF signal, such as the IF for offset and precise frequency 45.74 or 45.76
MHz, connects to the board. The external IF CW Input connects at J41A pin 32A and is
connected to J19 and through the external cable assembly W10 back to the board at J20.
The external IF CW input is split on the board. One branch connects through C157 to a
buffer amplifier Q20 to the K2 relay at pin 14. The other path is through C152 to the
amplifier U23A. The output of U23A is split with one part connecting to Q26 that shuts
down the 45.75 MHz oscillator. Another path connects to Q25 the conducts and lights the
LED DS7, Alternate IF, viewed on the front panel. The final path connects through R268
to Q22 that is biased on and energizes the relay, K2. The external IF CW Input at contact
14 now connects through the closed contact to the splitter network consisting of L31 and
L32.
Either the internal or external CW IF from the K2 relay is split with one path through L31
to the amplifier U28 to the L input of Z1 the Aural IF Mixer. The other path is through L32
to the amplifier U29 to the L input of Z2 the Visual IF Mixer.
4.1.1.11 Visual Modulator Circuit
The video signal is heterodyned in mixer Z2 with the visual IF CW signal (45.75 MHz). The
visual IF CW signal from L32 of the splitter connects to U29, where it is amplified and
wired to pin 1, the L input of mixer Z2. Adjustable capacitor C168 and resistor R275 are
set up to add a small amount of incidental carrier phase modulation (ICPM) correction to
the output of the mixer stage to compensate for any non-linearities generated by the
mixer.
The modulated 45.75-MHz RF output of mixer Z2, at pin 4 the R output, is amplified by
U30 and is fed to J17 through W8, the external cable assembly, “WB”, to J13 on the
board. J17 is the visual IF loop-through output jack that is normally jumpered to J13 on
the board. The modulated visual IF through J13 connects to J41C pin 17C the Visual IF
Output of the board.
4.1.1.12 Aural Modulator Circuit
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The 4.5 MHz aural modulated signal is heterodyned in mixer Z1 with the 45.75 MHz IF CW
signal. The mixer Z1 heterodynes the aural-modulated, 4.5-MHz signal with the 45.75MHz CW signal to produce the modulated 41.25-MHz aural IF signal. The audio modulated
4.5 MHz from 4.5 MHz VCO IC U16 connects, “J”, to the I input at pin 5 of Z1. The visual
IF CW signal from L31 of the splitter connects to U28, where it is amplified and wired to
pin 1, the L input of mixer Z1. The R output of the mixer at pin 4 is fed to a bandpass
filter, consisting of L18-L21, L25-L28 and C136, C137 and C142-144, that is tuned to pass
only the modulated 41.25-MHz aural IF signal. The filtered 41.25 MHz is fed to the
amplifier U27. The amplified 41.25-MHz signal is connected by a coaxial cable, W9, from
J21, “WC”, to J18 on the board. The modulated 41.25-MHz aural IF signal from J18 is
connected to J41C pin 6C the Aural IF Output of the board.
4.1.1.13 Combining the 45.75 MHz Visual
IF and 41.25 MHz Aural IF Signals
The Visual IF connects back to the board at J41C pin 3C, through a Visual IF jumper cable
connected to the rear chassis of the exciter/driver. IF processing equipment can be
connected in place of the jumper if needed. The visual IF is connected to J12, through
jumper W7, “WA”, to J14. The visual IF is amplified by U24 and filtered by FL1 with T1
and T2 providing isolation. The filtered IF is amplified by U25 and adjusted in level by
R214 before it is connected to a summing circuit at the common connection of L16 and
L17.
The Aural IF connects back to the board at J41C pin 23C, through an Aural IF jumper
cable connected to the rear chassis of the exciter/driver. IF processing equipment can be
connected in place of the jumper if needed. The aural IF, “F”, is connected through C132,
R234, R235 and adjusted in level by R243 before it is connected to a summing circuit at
the common connection of L17 and L16.
The Aural IF and Visual IF signals are combined through L16 and L17. The frequency
response of the combined 41.25 MHz + 45.75 MHz signal is set by R238 and R239 and
associated components. The corrected combined IF signal is amplified by U25 and
connected to a splitter matching network consisting of T3 and T4. One part of signal
connects to J10, the 41.25 MHz + 45.75 MHz sample output jack, located on the front
panel. The other part, “G”, connects to J41C pin 28C the Combined IF Output of the
board.
4.1.1.14 Voltage Requirements
The ±12 VDC needed for the operation of the board enters through jack J41A pins 25A
(+12 VDC) and 26A (-12 VDC). The +12 VDC is filtered by L6, L7, and C27 before it is
connected to the rest of the board. The +12 VDC also connects to U7, a 5-volt regulator
IC, that provides +5 VDC to the rest of the board.
The -12 VDC is filtered by L5, C16, and C17 before it is connected to the rest of the board.
4.2 (A3) IF Processor Module Assembly (Appendix B)
The IF from the 8 VSB modulator enters the module and the signal is pre-corrected as
needed for amplitude linearity correction, Incidental Carrier Phase Modulation (ICPM)
correction and frequency response correction.
The Module contains the following board.
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4.2.1 IF Processor Board (Appendix B)
The automatic level control (ALC) portion of the board provides the ALC and amplitude
linearity correction of the IF signal. The ALC adjusts the level of the IF signal that controls
the output power of the transmitter.
The IF from the 8 VSB modulator enters the board at J1B pin 32B. If the (optional)
receiver tray is present, the IF input (-6 dBm) from the 8 VSB modulator tray connects to
the modulated IF input jack J1C Pin 21C. The modulated IF input connects to relay K3 and
the receiver IF input connects to relay K4. The two relays are controlled by the Modulator
Select command that is connected to J1C Pin 14C on the board. Modulator select
enable/disable jumper W11 on J29 controls whether the Modulator Select command at J1C
Pin 14C controls the operation of the relays. With jumper W11 on J29 between pins 1 and
2, the Modulator Select command at J1C Pin 14C controls the operation of the relays; with
jumper W11 on J29, pins 2 and 3, the modulator is selected all of the time.
4.2.1.1 Modulator Selected
With the modulator selected, J1C-14C low, this shuts off Q12 and causes Pin 8 on the
relays to go high that causes relays K3 and K4 to de-energize. When K4 is de-energized, it
connects the receiver IF input at J1C-21C, if present, to a 50O load. When K3 is deenergized, it connects the modulator IF input at J1B-32B to the rest of the board;
Modulator Enable LED DS5 will be illuminated.
4.2.1.2 External Modulated IF Selected
With the External Modulated IF selected, J1C-14C high, this turns on Q12 and makes pin 8
on the relays low that causes the relays K3 and K4 to energized. When K4 is energized, it
connects the receiver IF input at J at J1C-21C, if present, to the rest of the board. When
K3 is energized, it connects to the modulator IF input at J1B-32B to a 50O load. The
Modulator Enable LED DS5 will not be illuminated.
4.2.1.3 Main IF Signal Path (Part 1 of 3)
The selected IF input (-6 dBm average) signal is split, with one half of the signal entering
a bandpass filter that consists of L3, L4, C4, L5, and L6. This bandpass filter can be tuned
with C4 and is substantially broader than the IF signal bandwidth. It is used to slightly
steer the frequency response of the IF to make up for any small discrepancies in the
frequency response in the stages that precede this point. The filter also serves the
additional function of rejecting unwanted frequencies that may occur if the tray cover is
off and the tray is in a high RF environment. (If this is the case, the transmitter will have
to be serviced with the tray cover off in spite of the presence of other RF signals). The
filtered IF signal is fed through a pi-type matching pad consisting of R2, R3, and R4 to the
pin-diode attenuator circuit consisting of CR1, CR2, and CR3.
4.2.1.4 Input Level Detector Circuit
The other part of the split IF input is connected through L2 and C44 to U7. U7 is an IC
amplifier that is the input to the input level detector circuit. The amplified IF is fed to T4,
which is a step-up transformer that feeds diode detector CR14. The positive-going
detected signal is then low-pass filtered by C49, L18, and C50. This allows only the
positive digital peaks to be applied through emitter follower Q1. The signal is then
connected to detector CR15 to produce a peak digital voltage that is applied to op-amp
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UHF Analog Driver/Transmitter
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U9A. There is a test point at TP3 that provides a voltage-reference check of the input
level. The detector serves the dual function of providing a reference that determines the
input IF signal level to the board and also serves as an input threshold detector.
The input threshold detector prevents the automatic level control from reducing the
attenuation of the pin-diode attenuator to minimum, the maximum signal output, if the IF
input to the board is removed. The ALC, input loss cutback, and the threshold detector
circuits will only operate when jumper W2 on jack J5 is in the Enabled position, between
pins 2 and 3. Without the threshold detector, and with the pin-diode attenuator at
minimum, the signal will overdrive the stages following this board when the input is
restored.
As part of the threshold detector operation, the minimum IF input level at TP3 is fed
through detector CR15 to op-amp IC U9A, pin 2. The reference voltage for the op-amp is
determined by the voltage divider that consists of R50 and R51, off the +12 VDC line.
When the detected input signal level at U9A, pin 2, falls below this reference threshold,
approximately 10 dB below the normal input level, the output of U9A at pin 1 goes high,
toward the +12 VDC rail. This high is connected to the base of Q2 that is forward biased
and creates a current path. This path runs from the -12 VDC line and through red LED
DS1, the input level fault indicator, which lights, resistor R54, and transistor Q2 to +12
VDC. The high from U9A also connects through diode CR16 and R52, to U24D pin 12,
whose output at pin 14 goes high. The high connects through the front panel accessible
ALC Gain pot R284 and the full power set pot R252 to U24C Pin 9. This high causes U24C
pin 8 to go low. A power raise/lower input from the Control/Monitoring Module connects
to J42C pin 24C and is wired to Q14. This input will increase or decrease the value of the
low applied to U24B and therefore increase or decrease the power output of the
transmitter.
The low connects to U24B pin 5 whose output goes low. The low is wired to U24A pin2
whose output goes high. The high is applied to U10A, pin 2, whose output goes low. The
low connects through the switch SW1, if it is in the auto gain position, to the pin-diode
attenuator circuit, CR1, CR2 & CR3. The low reverse biases them and cuts back the IF
level, therefore the output level, to 0. When the input signal level increases above the
threshold level, the output power will increase, as the input level increases, until normal
output power is reached.
The digital input level at TP3 is also fed to a pulse detector circuit, consisting of IC U8,
CR17, Q3, and associated components, and then to a comparator circuit made up of U9C
and U9D. The reference voltage for the comparators is determined by a voltage divider
consisting of R243, R65, R66, and R130, off the -12 VDC line. When the input signal level
to the detector at TP3 falls below this reference threshold, which acts as a loss-of-digital
peak detector circuit, the output of U9C and U9D goes towards the -12 VDC rail and is
split, with one part biasing on transistor Q5. A current path is then established from the
+12 VDC line through Q5, the resistors R69 and R137, and the red LED DS3, input loss
indicator, which is illuminated. When Q5 is on, it applies a high to the gate of Q6. This
causes it to conduct and apply a modulation loss pull-down output to J42C, pin 7C, which
is applied to the front panel display on the Control/Monitor module.
The other low output of U9C and U9D is connected through CR18, CR19 & CR20 to jack
J5. Jumper W2 on J5, in the Cutback Enable position, which is between pins 2 and 3,
connects the low to the base of Q4 that is now forward-biased. NOTE: If jumper W2 is in
the Disable position, between pins 1 and 2, the auto cutback will not operate. With Q4
biased on, a negative level determined by the setting of cutback level pot R71 is applied to
U24D, pin 12. The level is set at the factory to cut back the output to approximately 25%.
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UHF Analog Driver/Transmitter
Chapter 4, Circuit Descriptions
The output of U24D at pin 14 goes low and is applied through the power adjust pot to
U24C, pin 9, whose output goes low.
The low connects to U24B, pin 5, whose output goes low. The low then connects to U24A,
pin 2, whose output goes high. The high is applied to U10A, pin 2, whose output goes
low. The low connects through the switch SW1, if it is in the auto gain position, to the to
the pin-diode attenuator circuit, CR1, CR2 & CR3. The low reverse biases them and cuts
back the level of the output to approximately 25%.
4.2.1.5 Pin-Diode Attenuator Circuit
The input IF signal is fed to a pin-diode attenuator circuit that consists of CR1, CR2 & CR3.
Each of the pin diodes contains a wide intrinsic region; this makes the diodes function as
voltage-variable resistors at this intermediate frequency. The value of the resistance is
controlled by the DC bias supplied to the diode. The pin diodes are configured in a pi-type
attenuator configuration where CR1 is the first shunt element, CR3 is the series element,
and CR2 is the second shunt element. The control voltage, which can be measured at TP1,
originates either from the ALC circuit when the switch SW1 is in the ALC Auto position,
between pins 2 and 3, or from pot R87 when SW1 is in the Manual Gain position, between
pins 1 and 2.
In the pin diode attenuator circuit, changing the amount of current through the diodes by
forward biasing them changes the IF output level of the board. There are two extremes of
attenuation ranges for the pin-diode attenuators. In the minimum attenuation case, the
voltage, measured at TP1, approaches the +12 VDC line. There is a current path created
through R6, through series diode CR3, and finally through R9 to ground. This path forward
biases CR3 and causes it to act as a relatively low-value resistor. In addition, the larger
current flow increases the voltage drop across R9 that tends to turn off diodes CR1 and
CR2 and causes them to act as high-value resistors. In this case, the shunt elements act
as a high resistance and the series element acts as a low resistance to represent the
minimum loss condition of the attenuator (maximum signal output). The other extreme
case occurs as the voltage at TP1 is reduced and goes towards ground or even slightly
negative. This tends to turn off (reverse bias) diode CR3, the series element, causing it to
act as a high-value resistor. An existing fixed current path from the +12 VDC line, and
through R5, CR1, CR2, and R9, biases series element CR3 off and shunt elements, diodes
CR1 and CR2, on, causing them to act as relatively low-value resistors. This represents
the maximum attenuation case of the pin attenuator (minimum signal output). By
controlling the value of the voltage applied to the pin diodes, the IF signal level is
maintained at the set level.
4.2.1.6 Main IF Signal Path (Part 2 of 3)
When the IF signal passes out of the pin-diode attenuator through C11, it is applied to
modular amplifier U1. This device contains the biasing and impedance-matching circuits
that makes it operate as a wide-band IF amplifier. The output of U1 connects to J40 that
is jumpered to J41. The J40 jack is available, as a sample of the pre-correction IF for
troubleshooting purposes and system setup. The IF signal is connector to a splitter Z1 that
has an in phase output and a 90° Quadrature output, which are then connected to the
linearity corrector portion of the board.
4.2.1.7 Amplitude and Phase
Pre-Correction Circuits
LX Series, Rev. 0
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UHF Analog Driver/Transmitter
Chapter 4, Circuit Descriptions
The linearity corrector circuits use three stages of correction, two adjust for any amplitude
non-linearities and one for phase non-linearities of the output signal. Two of the stages
are in the in phase amplitude pre-correction path and one stage is in the quadrature
phase pre-correction path. Each stage has a variable threshold control adjustment, R211
and R216, in the in phase path, and R231, in the quadrature path, that determines the
point at which the gain is changed for that stage.
Two reference voltages are needed for the operation of the corrector circuits. The Zener
diode VR3, through R261, provides the +6.8 VDC reference. The VREF is produced using
the path through R265 and the diodes CR30 and CR31. They provide a .9 VDC reference,
which temperature compensates for the two diodes in each corrector stage.
The first corrector stage in the in phase path operates as follows. The in phase IF signal is
applied to transformer T6, which doubles the voltage swing by means of a 1:4 impedance
transformation. Resistors R222 and R225 form an L-pad that lowers the level of the signal.
The input signal level when it reaches a certain level causes the diodes CR24 and CR25 to
turn on, generating current flow that puts them in parallel with the L-pad. When the
diodes are put in parallel with the resistors, the attenuation through the L-pad is lowered,
causing signal stretch.
The signal is next applied to amplifier U17 to compensate for the loss through the L-pad.
The breakpoint, or cut-in point, for the first corrector is set by controlling where CR24 and
CR25 turn on. This is accomplished by adjusting the threshold cut-in resistor R211. R211
forms a voltage-divider network from +6.8 VDC to ground. The voltage at the wiper arm
of R211 is buffered by the unity-gain amplifier U16B. This reference voltage is then
applied to R215, R216, and C134 through L44 to the CR24 diode. C134 keeps the
reference from sagging during the vertical interval. The .9 VDC reference voltage is
applied to the unity-gain amplifier U16D. The reference voltage is then connected to diode
CR25 through choke L45. The two chokes L44 and L45 form a high impedance for RF that
serves to isolate the op-amp ICs from the IF.
After the signal is amplified by U17, it is applied to the second corrector stage in the in
phase path through T7. These two correctors and the third corrector stage in the
quadrature path operate in the same fashion as the first. All three corrector stages are
independent and do not interact with each other.
The correctors can be disabled by moving jumper W12 on J30 to the Disable position,
between pins 1 and 2, this moves all of the breakpoints past the greatest peaks of digital
so that they will have no affect.
The pre-distorted IF signal in the in phase path, connects to an op amp U18 whose output
level is controlled by R238. R238 provides a means of balancing the level of the
amplitude pre-distorted IF signal that then connects to the combiner Z2.
The pre-distorted IF signal in the quadrature path connects to op amp U20 and then step
up transformer T9, next op amp U21 and step up transformer T10 and finally op amp U22
whose output level is controlled by R258. R258 provides a means of balancing the level of
the Phase pre-distorted IF signal that then connects to the combiner Z2.
The amplitude and phase pre-distorted IF signals are combined by Z2 and connected to
J37 that is jumpered to J36 on the board. J37 can be used for testing or monitoring
purposes of the IF signal after amplitude and phase pre-distortion. The pre-distorted IF
signal connects through a resistor buffer network that prevents loading of the combiner
before it is wired to the frequency response circuitry.
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UHF Analog Driver/Transmitter
Chapter 4, Circuit Descriptions
4.2.1.8 Main IF Signal Path (Part 3 of 3)
The IF signal, at the input to the frequency-response corrector circuit, is split using L24,
L25 and R89. One path is through L24, which is the main IF path through the board. The
main IF is fed through a resistor network that controls the level of the IF by adjusting the
resistance of R99, the output level adjust. The IF signal is then applied to a three-stage,
frequency-response corrector circuit that is adjusted as needed.
The frequency-response corrector circuit operates as follows. Variable resistors R103,
R106 and R274 are used to adjust the depth and gain of the notches and variable caps
C71, C72 and C171 are used to adjust the frequency position of the notches. These are
adjusted as needed to compensate for frequency response problems.
The frequency-response corrected IF is connected to J38 that is jumpered to J39 on the
board. J38 can be used for testing or monitoring purposes of the IF signal after frequency
response pre-correction.
The IF is next amplified by U13 and U14. After amplification, the IF is split with one path
connected to J42C pin 1C the IF output to the LO/Upconverter Module. The other path is
fed through a divider network to J35 a SMA IF Sample Jack, located on the front panel,
which provides a sample of the corrected IF for test purposes.
4.2.1.9 ALC Circuit
The other path of the corrected IF signal at the input to the frequency response corrector
circuit is used in the ALC circuit. The IF flows through L25, of the L24 L25 splitter, and
connects to the op-amp U12. The IF signal is applied through a resistor divider network to
transformer T5. T5 doubles the voltage swing by means of a 1:4 impedance
transformation before it is connected to the ALC detector circuit, consisting of C70, CR23
and R91. The detected ALC level output is amplified by U10B and wired to U10A, pin 2,
where it is summed with the power control setting, which is the output power setting that
is maintained by the ALC. The output of U10A connects through SW1, if it is in the auto
gain position, to the pin-diode attenuator circuit, CR1, CR2 & CR3. The high forward
biases them more or less, that increases or decreases the IF level, therefore the output
level, opposite the input level. When the input signal level increases, the forward bias on
the pin attenuator decreases, therefore the output power will decrease, which keeps the
output power the same as set by the customer.
An external power raise/lower switch can be used by connecting it to TB30, at TB30-8
power raise and TB30-9 power lower, on the rear of the exciter/amplifier chassis. The
ALC voltage is set for .8 VDC at TP4 with a 0-dBm output at J42C pin 1C of the module. A
sample of the ALC at J42C pin 11C, is wired to the Control Monitoring/Power Supply
module where it is used on the front panel display and in the AGC circuits.
The ALC voltage, and the DC level corresponding to the IF level after signal correction, are
fed to U10A, pin 2, whose output at pin 1 connects to the ALC pin-diode attenuator circuit.
If there is a loss of gain somewhere in an IF circuit, the output power of the transmitter
will drop. The ALC circuit senses this drop at U10A and automatically decreases the loss
through the pin-diode attenuator circuit therefore increasing its gain maintaining the same
output power level.
The ALC action starts with the ALC detector level monitored at TP4. The detector output at
TP4 is nominally +.8 VDC and is applied through resistor R77 to a summing point at
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UHF Analog Driver/Transmitter
Chapter 4, Circuit Descriptions
op-amp U10A, pin 2. The current available from the ALC detector is offset, or
complemented, by current taken away from the summing junction. In normal operation,
U10A, pin 2, is at 0 VDC when the loop is satisfied. If the recovered or peak-detected IF
signal level at IF input to this board should drop, which normally means that the output
power will decrease, the null condition would no longer occur at U10A, pin 2. When the
level drops, the output of U10A, pin 1, will go more positive. If SW1 is in the Automatic
position, it will cause the ALC pin-diode attenuators CR1, CR2, and CR3 to have less
attenuation and increase the IF level; this will compensate for the decrease in the level. If
the ALC cannot increase the input level enough to satisfy the ALC loop, due to there not
being enough range, an ALC fault will occur. The fault is generated because U10D, pin 12,
increases above the trip point set by R84 and R83 until it conducts. This makes U10D, pin
14, high and causes the red ALC Fault LED DS2 to light.
4.2.1.10 Fault Command
The board also has circuitry for an external mute fault input at J42 pin 10C. This is a Mute
command that protects the circuits of high-gain output amplifier devices against VSWR
faults. This action needs to occur faster than just pulling the ALC reference down. Two
different mechanisms are employed: one is a very fast-acting circuit to increase the
attenuation of the pin-diode attenuator, CR1, CR2, and CR3, and the second is the
reference voltage being pulled away from the ALC amplifier device. An external Mute is a
pull-down applied to J42 pin 10C, which completes a current path from the +12 VDC line
through R78 and R139, the LED DS4 (Mute indicator), and the LED section of opto-isolator
U11. These actions turn on the transistor section of U11 that applies -12 VDC through
CR21 to U10A pin 3, and pulls down the reference voltage. This is a fairly slow action
controlled by the low-pass filter function of R81 and C61. When the transistor section of
U11 is on, -12 VDC is also connected through CR22 directly to the pin-diode attenuator
circuit. This establishes a very fast muting action, by reverse biasing CR3. This action
occurs in the event of an external VSWR fault.
4.2.1.11 ±12 VDC Needed to Operate the
Board
The ±12 VDC connects to the board at J42C. The +12 VDC connects to J42C pin 16C and
is filtered by L30, L41, and C80 before it is applied to the rest of the board. The -12 VDC
connects to J42C pin 18C and is filtered by L31 and C81 before it is applied to the rest of
the board.
The +12 VDC also connects through R261 to the zener diode VR3 that connects to ground,
which generates the +6.8 VDC output to the rest of the board.
The +12 VDC also connects through R265 to the diodes CR30 and CR31 provide a .9 VDC
reference output voltage VREF that temperature compensates for the two diodes in each
corrector stage.
4.3 (A5) LO/Upconverter Module (Appendix B)
This module contains the LO/Upconverter board, the UHF Generator Board, LED Display
Board and channel filters. This module takes an external IF and converts it to the final
RF output frequency using an internally generated local oscillator.
The local oscillator consists of a VCXO that is phase locked to an external 10 MHz
reference. The 10 MHz reference and the VCO are both divided down to 5 kHz and
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UHF Analog Driver/Transmitter
Chapter 4, Circuit Descriptions
compared by the phase lock loop circuit. Any error from this comparison is generated in
the form of an error current that is converted to a bias voltage that connects to the VCO.
This voltage adjusts the output frequency of the VCO until it is on the desired frequency.
The Phase lock loop is programmed by loading in data generated by the control module.
This data sets the dividers so that the 10MHz and the VCXO frequency are divided to
5kHz. These divide numbers are loaded into U6 using the clock, data and LE lines. This
data is sent whenever the module is first plugged into the backplane board or when
power is applied to the transmitter. This is necessary because the divide numbers are
lost when power is removed from the module.
There is an alarm generated if the phase locked loop is unlocked. This alarm is displayed
locally and is also sent to the control module in the transmitter to be displayed as a
fault. The bias voltage to the VCO is also available to be monitored at TP1 and also can
be viewed on the front panel display of the Transmitter. Typical values for this voltage
are 0.1 to 0.5V. The 10 MHz reference is normally an external reference. There is also
a high stability internal reference option that is available if there is a desire to operate
the transmitter without an external reference. Jumper W1 determines whether an
external or internal high stability reference is to be used.
The IF signal is applied at a level of
–15 dBm average and is converted to the final RF channel frequency. The RF signal is
applied to a filter that selects the right conversion product. Next, the signal is amplified
to -7 dBm by A3 and exits the front of the module at J2. There are also a front panel
samples of the RF output at J3 and the LO at J1. The RF sample level is approximately 20 dB below the RF output. The LO sample level is -7 dBm.
4.3.1 (A4) UHF Generator Board ( Appendix B)
The UHF generator board is mounted in the UHF Generator Enclosure for EMI and RFI
protection. The board contains a VCXO circuit and additional circuitry to multiply the VCXO
frequency by eight.
The VCXO circuit uses the crystal Y1, mounted in a crystal oven for stability, to produce an
output of ≈ 67 MHz to 132 MHz, depending on the desired channel frequency. Course
adjustment to the frequency of the crystal is made by C11, while fine adjustments are
accomplished by the AFC voltage at J2 from (A1) the LO/Upconverter board (1302132).
The VCXO output level is adjusted by C6, L2, L4 and C18. The output is split and provides
an input to the x8 multiplier circuitry as well as a VHF Output sample at J1.
The x8 circuitry consists of three identical x2 broadband frequency doublers. The input
signal at the fundamental frequency is fed through a 6-dB pad consisting of R21, R24, and
R25 through C29 to amplifier U3. The output of the amplifier stage is directed through a
bandpass filter consisting of L8 and C32, which is tuned to the fundamental frequency (67
MHz to 132 MHz). The voltage measured at TP1 is typically +.6 VDC. The first doubler
stage consists of Z1 with bandpass filter L9 and C34 tuned to the second harmonic (134
MHz to 264 MHz). The harmonic is amplified by U4 and again bandpass filtered at the
second harmonic by C38 and L11 (134 MHz to 264 MHz). The voltage measured at TP2 is
typically +1.2 VDC. The next doubler stage consists of Z2 with bandpass filter C40 and L12
tuned to the fourth harmonic of the fundamental frequency (268 MHz to 528 MHz). The
fourth harmonic is then amplified by U5 and fed through another bandpass filter tuned to
the fourth harmonic consisting of L14 and C44 (268 MHz to 528 MHz). The voltage
measured at TP3 is typically +2.0 VDC. The final doubler stage consists of Z3 with
bandpass filter C46 and L15 tuned to the eighth harmonic of the fundamental frequency
LX Series, Rev. 0
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UHF Analog Driver/Transmitter
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(536 MHz to 1056 MHz). The signal is amplified by U6 and U7 to a typical value of from +2
to +4 VDC as measured at TP4. The amplified eighth harmonic is then fed to the SMA RF
output jack of the board at J3. Typical output level of the signal is +16 dBm nominal. This
output connects through A5 a channel filter to the LO/Upconverter Board.
The DC voltages needed to operate the UHF generator board are supplied by the
LO/Upconverter Board. The +12 VDC for the board enters through jack J4-3 and is filtered
by L22 and C54-C58 before being distributed to the circuits on the board.
The +9 VDC for the board enters through jack J4-1 and is distributed to the rest of the
board.
4.3.3 (A1) LO/Upconverter Board ( Appendix B)
The upconverter portion of the board
The LO/Upconverter board provides upconversion processing by mixing the IF and LO
signals in mixer Z1 to produce the desired RF frequency output. The RF output is
connected through J4 to A5, an external channel filter, and applied back to the board at
J6. The RF is amplified and connected to the RF output jack of the board at J43-25B.
The IF signal (-6 dBm average) enters the board at J43-2B and is applied through a
matching pad and filter circuit to the mixer. The pad consists of R6, R2 and R7, which
presents a relatively good source impedance. The IF is then connected through a voltage
divider network consisting of R3, R4, R8 and R14. R14 is variable and adjusted to set the
0 dBm IF input level to the mixer. The IF in next filtered by L3, C84 and C83 and
connected to pin 5, the I input of the mixer Z1.
The local oscillator signal (+13 dBm) from UHF Generator Board, through (A5) a UHF
channel filter, connects to the board at jack J1, an SMA connector. THE LO is connected
directly to pin 1, the L input of the mixer Z1.
The frequency of the LO is the sum of the IF frequency above the required digital carrier.
For instance, in system M, for digital applications, the LO is the center frequency of the
digital channel added to the 44-MHz IF frequency. By picking the local oscillator to be 44
MHz above the digital carrier, a conversion in frequency occurs by selecting the difference
product. The difference product, the local oscillator minus the IF, will be at the desired
digital carrier frequency output. There will also be other signals present at the RF output
connector J3 at a lower level. These are the sum conversion product: the LO and the IF
frequencies. Usually, the output product that is selected by the tuning of the external filter
is the difference product: the LO minus the 44-MHz IF.
If a bad reactive load is connected to the mixer, the LO signal that is fed through it can be
increased because the mixer no longer serves as a double-balanced mixer. The mixer has
the inherent property of suppressing signals that may leak from one input port to any of
the other ports. This property is enhanced by having inputs and outputs of the mixer at
50Ω impedance. The RF output of the mixer connects through a pad made up of R12,
R15, and R17 before it is wired to the amplifier U2. The RF signal is amplified by U2, a
modular amplifier, and includes within it biasing and impedance matching networks that
makes U2 act as a wideband-RF amplifier device. This amplifier, in a 50Ω system, has
approximately 12 dB of gain. U2 is powered from the +12 VDC line through RF decoupling
components R24, C14, and L4. Inductor L4 is a broadband-RF choke and is resonance free
through the UHF band. The amplified RF connects through a pad to the SMA RF output
jack J4 and is cabled to (A2) an external channel filter. The reactive channel filter that is
LX Series, Rev. 0
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UHF Analog Driver/Transmitter
Chapter 4, Circuit Descriptions
externally connected to J4 of the board does not appear as a good 50-Ω load at all
frequencies. The pad, in the output line of the board, consisting of R20, R18, and R21
buffers the bad effects of the reactive filter load and makes it appear as a 50Ω impedance.
The RF input signal from the external filter re-enters the board at J6 (-11 to -17 dBm) and
is capacitively coupled to the pin-diode attenuator circuit consisting of CR2, CR3, and CR4.
The pin-diode attenuator acts as a voltage-variable attenuator in which each pin diode
functions as a voltage-variable resistor that is controlled by the DC bias connected to the
diodes. The pin diodes, because of a large, intrinsic region, cannot rectify signals at this RF
frequency; therefore, they only act as a linear voltage-variable resistor. These diodes are
part of the AGC for the transmitter.
The automatic gain control (AGC) portion of the board
The automatic gain control (AGC) provides automatic gain control for the power amplifier
module(s).
The AGC circuitry attempts to maintain the ratio between an input reference proportional
to the input power and the output power of either the exciter/amplifier PA output, AGC
#1, Inner Loop, or the output of external power amplifiers, AGC #2, Outer Loop, farther
downstream. NOTE: The AGC #2 Outer Loop is not used in 5W-50W digital
transmitters.
An ALC reference input is applied to the board at J43-16A, amplified by U10A, and sent
to the front panel board through J5-7 where it is connected to a AGC Manual Gain pot,
accessed through the front panel. A switch AUTO/MAN AGC is also located on the front
panel. When switched in MAN the MAN GAIN Pot adjusts the output power level. The
Gain Control voltage is reapplied to the board at J5-6. The gain control voltage is
summed to the added together inner and outer loop AGC reference voltage at U10D.
The AGC output reference from the exciter/amplifier PA module, AGC #1 INNER LOOP, is
applied at J43-14C and from the external PA module, AGC #2 OUTER LOOP, is applied at
J43-15C.
The larger voltage of either the inner or the outer loop is used to control the AGC loop.
Since the outer loop is not used in this system, the inner loop controls the AGC. R82 is
adjusted so that the inner loop voltage at TP7 is larger than the voltage at TP4 by
approximately .1 VDC. This ensures that the output of the exciter/amplifier is the
reference used for AGC. In systems that use the outer loop, that level is adjusted to .1
VDC above the inner loops reference. This ensures that the output of the system is the
reference used for AGC. If that reference drops to the point where it is smaller than the
inner loop reference, the system switches over to using the inner loop reference.
The AGC reference that is being used is buffered by U10C and connected to U10D.
U10D generates an output voltage that is used to bias the pin attenuators, CR2, CR3
and CR4, which sets the gain of the exciter/amplifier.
This Auto AGC circuit can be disabled by the AGC Auto/Man switch, located on the front
panel, which switches the pin-attenuator bias to a variable voltage that is set by the
Manual Gain Adjust.
The level-controlled RF signal, from the pin-diode attenuator circuit, is amplified by the
wideband-hybrid amplifier IC U13 that is configured in the same way as U2. The RF signal
is converted by T1 to a balanced, dual feed output that is applied to the push-pull Class A
LX Series, Rev. 0
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UHF Analog Driver/Transmitter
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amplifier IC U1. Capacitors C2 and C5 provide DC blocking for the input signal to the IC.
The RF outputs of the IC are applied through C3 and C4, which provide DC blocking for
the output signals. The RF signals connect to combiner T2 that combines the RF back to a
single-RF output at a 50Ω impedance. The RF then enters a coupler stage, which provides
a sample of the RF at J7 (–20dB), the front panel RF sample jack. The main path through
coupler is to J43 pin 25B, the Upconverter RF output jack of the module (+0 to +10 dBm).
The PLL and 10-MHz Reference section of the Board
The PLL and 10-MHz reference portion of the board utilizes either an external 10 MHz
reference or an internally generated 10 MHz as the reference for the PLL circuit that
generates the AFC voltage, which controls the frequency of the VCXO on the UHF
Generator Board.
The (PLL) phase lock loop circuit, provides the automatic frequency control (AFC) voltage,
that connects to the VCXO, located on the UHF generator board, and maintains the
accurate output frequency of the VCXO. The AFC is generated by comparing a sample of
the 10-MHz reference to a sample of the VCXO frequency. The PLL uses an external 10MHz signal as the reference, unless it is missing, then an internally generated 10-MHz
signal is used. The two 10-MHz reference signals are connected to the K1 relay and the
selected reference connects to the comparator synthesizer IC U9. The switching between
the two references is accomplished by the K1 relay. When the relay is de-energized, it
applies the external 10-MHz reference to U9. The relay will remain de-energized as long
as an externally generated 10-MHz reference signal is present and the Jumper W3 on J10
is placed in the external position, between Pins 1 & 2. An alternate 10 MHz reference can
be connected to J11 on the board. The jumper W3 on J10 must then be moved to pins 2
& 3, internal, to connect the alternate 10 MHz to K1. The alternate 10 MHz will then act in
the circuit like the external 10 MHz.
If the external 10-MHz reference is lost, the relay will energized and the internally
generated 10-MHz reference is then applied through the K1 relay pin 14 to pin 1 to the IC
U9.
With the relay de-energized, the externally generated 10-MHz from jack J43 pin 22B
connects through the normally closed contacts of the relay from pin 1 to pin 7 to the IC
U9.
External 10-MHz Reference Present Circuitry
The external 10-MHz reference signal enters the board at J43 pin 22B and is isolated by
L8 and connected to the External/Internal Jack J10. W3 on J10 is a manual jumper that
must be connected between pins 1 & 2, External, for the external 10 MHz to connect to
the rest of the circuit. The external 10 MHz is filtered by C44, R55, L9 and C46 before it
split with one path connected to the K1 relay at pin 1 of the normally closed contacts. The
other path takes the 10 MHz and rectifies it by CR5 and filters it before it is connected to
U7A pin 2. If the sample level of the external 10 MHz is above the reference set by R46
and R48, which is connected to pin 3 of U7A, the output of U7A stays low. The low
connects to the gates of Q3, Q5 and Q6, which are biased off and cause their drains to go
high. The high from the drain of Q6 is wired to J43, pin 14A, for connection to a remote
external 10-MHz present indicator. The high from the drain of Q5 connects to the yellow
LED DS2, internal reference indictor, which will not light. This indicates that an external
10-MHz reference is present. The low from U7A also connects to the gate of Q3, biasing it
off and causing its drain to go high. This high de-energizes the K1 relay and applies the
LX Series, Rev. 0
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UHF Analog Driver/Transmitter
Chapter 4, Circuit Descriptions
external 10-MHz reference signal to pin 6 on U9 for use as the reference in the PLL
circuits.
Internal 10-MHz Reference Circuitry
The internally generated 10-MHz reference signal connects from U6, the 10-MHz oscillator
IC, to pin 14, the Normally Open contacts of relay K1.
With no external 10-MHz reference input, the level connected to U7A Pin 2 will be low.
This will be less than the reference set by R46 and R48, which is connected to pin 3 of
U7A, that causes the output of U7A to go high. The high connects to the gates of Q3, Q5
and Q6, which are biased on and causes their drains to go low. The low from the drain of
Q6 is wired to J43, pin 14A, for connection to a remote external 10-MHz present indicator.
The low from the drain of Q5 connects to the yellow LED DS2, internal reference indictor,
which will light. This indicates that an external 10-MHz reference is not present and that
the internal 10-MHz is being used as the reference. The high from U7A also connects to
the gate of Q3, biasing it on and causing its drain to go low. This low energizes the K1
relay and applies the internal 10-MHz reference signal through K1 pin 14 to pin 7 to pin 6
on U9 for use as the reference in the PLL circuits.
Selected 10-MHz Reference Samples
A sample of the selected 10-MHz is split off the main path through L13 and R95 using L14
and C74 and C73. The sample path connects to another splitter circuit consisting of L2,
R94, L11, C71 and C70. One output of the splitter connects to J43 pin 28B that is used by
the external digital modulator tray. The other output of the splitter connects to J43 pin
31B that is used by the external analog modulator tray.
Comparator Phase Lock Loop Circuit
The selected 10-MHz reference connects to pin 6, Oscillator In, of the IC U9. The LO
generated by the VCXO located on the UHF Generator Board connects to J1 on the
LO/Upconverter Board. A sample of the LO is divided off the main line by R105, R106 and
R107. The LO sample connects to pin 4, F In, of U9.
The U9 IC takes the 10 MHz reference and divides it down to 5 kHz. It also takes the LO
sample input and divides it down to 50 kHz. The two 5 kHz divided down signals are
compared inside of U9 and any differences are connected to U9 pin 16. The output of U9
at pin 16 are 5 kHz pulses whose pulse width varies as any differences between the 10MHz and VCXO frequencies are detected. These pulses are changed to a DC voltage level
by the capacitor-resistor filter network, C32, C36, C42, C38 and R49. The AFC voltage is
then connected to the + input of U4B that amplifies it and connects it to jack J9. W2 on
J9 must be in the operate position, between pins 1 and 2, for the PLL circuit to operate.
With jumper W2 between pins 2 and 3 on J6, set up, the AFC bias is set by R43. NOTE:
With the VCXO, located on the UHF Generator Board, set on frequency, the voltage as
measured at TP2 should be –2 VDC.
The AFC output of J9 is split with one path connected to J43 pin 13A. The other path is
amplified by U7B and connected to J12, VCXO AFC Output, on the board that connects to
the VCXO on the UHF generator board. The PLL circuit, when locked, will maintain the
very accurate VCXO output frequency because any change in frequency will be corrected
by the AFC error voltage.
Lock Detector Circuit
LX Series, Rev. 0
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UHF Analog Driver/Transmitter
Chapter 4, Circuit Descriptions
IC chip U9 contains an internal lock detector that indicates the status of the PLL circuit.
When U9 is in a locked state, pin 12 goes high; the high is applied to Q1, which is biased
off. With Q1 off, pin 3 goes low and is connected to DS1, the Red Unlock LED, which does
not lit. Q1 pin 3 low also connects to Q2 that is biased off. The drain of Q2, a high, is
wired to J43 pin 15A, the PLL Lock Indicator output of the board.
If the 5-kHz from the 10-MHz reference and the 5-kHz from the VCXO become unlocked,
out of the capture range of the PLL, pin 12 of U9 goes to a logic low that connects to the
base of Q1. This biases On Q1 causing pin 3 to go high. The high connects to DS1, the
red Unlock LED, which lights, and to Q2, which is biased on. When Q2 is biased on, it
connects a low to jack J43 pin 15A, the PLL Lock Indicator output of the board.
Voltage Requirements
The board is powered by ±12 VDC that is produced by an external power supply. +12
VDC enters the board through J43 pins 18A, B & C, and is filtered and isolated by L5, L6
and the shunt capacitor C24. The +12 VDC is then applied to the rest of the board and to
J14 pin 3 for use by the UHF Generator Board.
One connection of the +12 VDC is to IC U12. U12 and associated circuitry produce a +9
VDC that connects to J14 pin 1 for use by the UHF Generator Board.
Another connection of the +12 VDC is to a +5 VDC regulator. The +12 VDC connects to
diodes CR6 and CR7 that along with the pi type filter consisting of C56, L10, C54 and C55
removes any noise from the +12 VDC before it connects to the +5 VDC regulator IC U8.
The output of the IC U8, +5 VDC, connects to the rest of the board.
The -12 VDC enters the board through J43 pins 19A, B & C and is filtered and isolated by
L7 and the shunt capacitor C28. The -12 VDC is then applied to the rest of the board and
to J14 pin 5 for use by the UHF Generator Board.
4.4 (A4) Control Monitoring/Power Supply Module (110 VAC, OR 220 VAC,
Appendix B)
The Control Monitoring/Power Supply Module Assembly contains (A1) a Power Protection
Board, (A2) a 600 Watt Switching Power Supply, (A3) a Control Board , (A4) a Switch
Board (1527-1406) and (A5) a LCD Display.
AC Input to Exciter/Amplifier Chassis Assembly
The AC input to the Pioneer Exciter/Amplifier Chassis Assembly is connected from J1, part
of a fused entry module, located on the rear of the chassis assembly to J50 on the
Control Monitoring/Power Supply Module. There are two possible modules that can be
part of your system, 1301936 for 110 VAC or 1303229 for 220 VAC operation. J50-10 is
line #1 input, J50-8 is earth ground and J50-9 is line #2 input. The input AC connects to
J1 on the Power Protection Board where it is fuse protected and connected back to J50, at
J50-11 AC Line #1 and J50-12 AC Line #2, for distribution to the cooling Fan.
4.4.1 (A1) Power Protection Board (Appendix B)
The input AC connects through J1 to two 10 Amp AC fuses F1 and F2. The AC line #1
input connects from J1-1 to the F1 fuse. The AC line #1 input after the F1 fuse is split
LX Series, Rev. 0
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UHF Analog Driver/Transmitter
Chapter 4, Circuit Descriptions
with one line connected back to Jack J1 Pin 4, which becomes the AC Line #1 to the Fan.
The other line of the split connects to J4. The AC line #2 input connects from J1-3 to
the F2 fuse. The AC line #2 input after the F2 fuse is split with one line connected back
to Jack J1 at Pin 5, which becomes the AC Line #2 to the Fan. The other line of the split
connects to J2. J1-2 is the earth ground input for the AC and connects to J3.
Three 150-VAC, for 115 VAC input, or three 275-VAC, for 230 VAC input, MOVs are
connected to the input AC for protection. One connects from each AC line to ground and
one connects across the two lines. VR1 connects from J4 to J2, VR2 connects from J4 to
J3 and VR3 connects from J2 to J3.
+12 VDC Circuits
+12 VDC from the Switching Power Supply Assembly connects to J6 on the board. The
+12 VDC is divided into four separate circuits each with a 3 amp self resetting fuse, PS3,
PS4, PS5 and PS6.
The polyswitch resettable fuses may open on a current as low as 2.43 Amps at 50°C, 3
Amps at 25°C or 3.3 Amps at 0°C. They definitely will open when the current is 4.86
Amps at 50°C, 6 Amps at 25°C or 6.6 Amps at 0°C.
PS3 protects the +12 VDC 2 Amp circuits for the System Controller, the Amplifier
Controller and the Spare Slot through J62 pins 7, 8, 9 and 10. If this circuit is
operational, the Green LED DS3, mounted on the board, will be lit.
PS4 protects the +12 VDC 2 Amp circuits for the Modulator and the IF Processor through
J62 pins 13, 14, 15 and 16. If this circuit is operational, the Green LED DS4, mounted
on the board, will be lit
PS5 protects the +12 VDC 2 Amp circuits for the Upconverter through J62 pins 17, 18,
19 and 20. If this circuit is operational, the Green LED DS5, mounted on the board, will
be lit
PS6 protects the +12 VDC 2 Amp circuits for the Remote through J63 pins 17, 18, 19
and 20. If this circuit is operational, the Green LED DS6, mounted on the board, will be
lit
-12 VDC Circuits
-12 VDC from the Switching Power Supply Assembly connects to J5 on the board. The 12 VDC is divided into two separate circuits each with a 3 amp self resetting fuse, PS1
and PS2.
PS1 protects the -12 VDC 2 Amp circuits for the System through J63 pins 1, 2, 3 and 4.
If this circuit is operational, the Green LED DS1, mounted on the board, will be lit
PS2 protects the -12 VDC 2 Amp circuits for the Remote through J62 pins 1, 2, 3 and 4.
If this circuit is operational, the Green LED DS2, mounted on the board, will be lit
The connections from J62 and J63 of the Power Protection Board are wired to J62 and
J63 on the Control Board.
LX Series, Rev. 0
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UHF Analog Driver/Transmitter
Chapter 4, Circuit Descriptions
4.4.2 (A3) Control Board (Appendix B)
In this transmitter, control monitoring functions and front panel operator interfaces are
found on the Control Board. Front panel operator interfaces are brought to the control
board using a 26 position conductor ribbon cable that plugs into J60. The control board
controls and monitors the Power Supply and Power Amplifier module through a 16
position connector J61 and two 20 position connectors J62 & J63.
Schematic Page 1
U1 is an 8 bit RISC microcontroller that is in circuit programmed or programmed using
the serial programming port J4 on the board. When the microcontroller, U1, is held in
reset, low on pin 20, by either the programming port or the external watchdog IC (U2),
a FET Q1 inverts the reset signal to a high that connects to the control lines of U5, an
analog switch. The closed contacts of U5 connects the serial programming lines from J4
to U1. LED DS10 will be lit when programming port J4 is used.
U2 is a watchdog IC used to hold the microcontroller in reset, if the supply voltage is
less the 4.21 VDC; (1.25 VDC < Pin 4 (IN) < Pin 2 (Vcc). The watchdog momentarily
resets the microcontroller, if Pin 6 (ST) is not clocked every second. A manual reset
switch S1 is provided but should not be needed.
Diodes DS1 through DS8 are used for display of auto test results. A test board is used
to execute self test routines. When the test board is installed, Auto_Test_1 is held low
and Auto_Test_2 is allowed to float at 5 VDC. This is the signal to start the auto test
routines.
U3 and U4 are used to selectively enable various input and output ICs found on pages 2
& 3 of the schematic.
U1 has two serial ports available. In this application, one port is used to communicate
with transmitter system components where U1 is the master of a RS-485 serial bus.
The other serial port is used to provide serial data I/O where U1 is not the master of the
data port. A dual RS-232 port driver IC and a RS-485 Port driver is also in the second
serial data I/O system. The serial ports are wired such that serial data input can come
through one of the three serial port channels. Data output is sent out through each of
the three serial port channels.
Switch SW1, transmitter operation select, is used to select either transmitter operation
or exciter/driver operation. When the contacts of SW1 are closed, transmitter operation
is selected and the power monitoring lines of the transmitter’s power amplifier are
routed to the system power monitoring lines.
Schematic Page 2
U9 is a non-inverting transceiver IC that provides 2 way asynchronous communication
between data busses. . The IC is used as an input buffer to allow the microcontroller to
monitor various digital input values.
Digital output latch circuits are used to control system devices. Remote output circuits
are implemented using open drain FETs, Q13, Q14, Q16, and Q17, with greater than 60
Volt drain to source voltage ratings.
LX Series, Rev. 0
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UHF Analog Driver/Transmitter
Chapter 4, Circuit Descriptions
Remote digital inputs are diode protected, using CR6, CR7, CR8 and CR9 with a 1 kO
pull-up resistor, to +5 VDC. If the remote input voltage is greater than about 2 Volts or
floating, the FET is turned on and a logic low is applied to the digital input buffer, U9. If
the remote input voltage is less than the turn on threshold of the FET (about 2 VDC), a
logic high is applied to the digital input buffer, U9.
Four of the circuits on page two of the schematic, which include Q2, Q9, Q19 and Q21,
are auxiliary I/O connections wired for future use. They are wired similar to the remote
digital inputs but include a FET, Q5, Q12, Q20 and Q22, for digital output operations. To
operate these signals as inputs, the associated output FET must be turned off. The FETs
are controlled by U10 and U12, analog input multiplexer ICs.
Schematic Page 3
U13, U14, U15, U16, U17 and U18 are 3 state non-inverting transceiver ICs that provide
2 way asynchronous communication between data busses. The ICs are used as input
buffers to allow the microcontroller to monitor various digital input values. The digital
inputs to the ICs utilize a 10 kO pull-up resistor. The buffer IC, U18, used for data
transfer to the display is wired for read and write control.
Schematic Page 4
U19 and U20 are digitally controlled analog switches that provide samples back to the
microprocessor. Each analog input is expected to be between 0 and 5 VDC. If a signal
exceeds 5.1 VDC, a 5.1 Volt zener diode clamps the signals voltage, to prevent damage
to the IC. Most signals are calibrated at their source, however two dual serial
potentiometers ICs are used to calibrate four signals, System Visual/Average Power,
System Aural Power, System Reflected Power and the Spare AIN 1. For these four
circuits, the input value is divided in half before it is applied to an op-amp. The serial
potentiometer is used to adjust the output signal level to between 80 and 120% of the
input signal level. Serial data, serial clock and serial pot enables are supplied by the
microprocessor to the dual serial potentiometer ICs. J62 and J63 are two 20 position
connectors that provide the +12 VDC and –12 VDC power through the Power Protection
Board. The ±12 VDC generated by the switching power supply connects to J62 and J63
after being fuse protected on the Power Protection Board.
Schematic Page 5
There are three dual element, red/green, common cathode LED indicators mounted on
the front panel of the sled assembly; DC OK, Operate and Fault.
There are three, the fourth is a spare, identical circuits that drive the front panel
mounted LED indicators. The levels on the 1, 2, 3 and 4 LED Control Lines, for both the
red and green LEDs, are generated by the IC U11 as controlled by the DATABUS from
the microprocessor U1.
Each LED controller circuit consists of an N-Channel MOSFET w/internal diode that
controls the base of an N-P-N transistor in an emitter follower configuration. The
emitter of the transistor connects the LED.
With the LED control line LOW, the MOSFET is Off, which causes the base of the
transistor to increase towards +12 VDC, forward biasing the transistor. With the
transistor forward biased, current will flow from ground through the LED, the transistor
LX Series, Rev. 0
4-21
UHF Analog Driver/Transmitter
Chapter 4, Circuit Descriptions
and the current limiting resistors in the collector to the +12 VDC source. The effected
LED will light.
With the LED control line HIGH, the MOSFET is On, which causes the base of the
transistor go toward ground potential, reverse biasing the transistor. With the transistor
reverse biased, no current through the transistor and LED, therefore the effected LED
will not light.
A third color, amber, can also be generated by having both transistors conducting, both
control lines LOW. The amber color is produced because the current applied to the
green element is slightly greater than the red element. This occurs because the current
limiting resistors have a smaller ohm value in the green circuit.
There are four voltage regulators, three for +5 VDC and one for +7 VDC, which are used
to power the Control Board. +12 VDC is applied to U25 the +7 VDC regulator that
produces the +7V, which is applied to the LEDs mounted on the board. The +7V is also
connected to the input of U26 a precision +5.0 Volt regulator. The +5.0Vdc regulator
output is used to power the analog circuits and as the microcontroller analog reference
voltage. Another two +5 Volt regulator circuits U27, +5V, and U8, +5 Vserial, are used
for most other board circuits.
4.4.3 (A4) Switch Board (Appendix B)
The switch board provides five front-panel momentary contact switches for user control
and interface with the front-panel LCD menu selections. The switches, SW1 to SW5,
complete the circuit through connector J1 to connector J2 that connects to J1 on (A5)
the 20 Character by 4 line LCD Display. J1 on the switch board is also cabled to the
Control Board. When a switch is closed, it connects a logic low to the control board that
supplies the information from the selected source to the display. By pushing the button
again, a different source is selected. This occurs for each push button. Refer to Chapter
3 Section 3.5.4, for more information on the Display Menu Screens.
4.4.4 (A2) Switching Power Supply Assembly
The power supply module contains a switching power supply, an eight position terminal
block for distributing the DC voltages, a three position terminal block to which the AC
Input connects, Jacks J1, V1 and V2. Jack J1 connects to the Control Board and supplies
DC OK, at J1-4 & 3, and AC OK, at J1-2 & 1, status to the control board. A Power
Supply enable connects from the control board to the power supply at V1-6 & 7. The
power supply is configured for three output voltages +12V, -12V, at the 8 position
terminal block, and a main output power of +32 VDC at J50 pin A (+) and J50 pin B
(Rtn). The power supply is power factor corrected to .98 for optimum efficiency and
decrease in energy consumption. For safety purposes all outputs are over voltage and
over current protected. This supply accepts input voltages from 85 to 264 volts AC, but
the power entry module, for the exciter/amplifier chassis, must be switched to the
proper input voltage setting, for the transmitter to operate.
4.5 (A4) Power Amplifier Module Assembly (Appendix B)
The Power Amplifier Module Assembly contains (A1) a 1 Watt UHF Amplifier Module
Assembly , (A2) a 100 Watt Driver Module Assembly, (A3) RES RF Module Pallet
Assembly, (A4) a Coupler Board Assembly, (A5) an Amplifier Control Board and (A6) a
Temperature Sensor IC.
LX Series, Rev. 0
4-22
UHF Analog Driver/Transmitter
Chapter 4, Circuit Descriptions
The RF from the Upconverter Module Assembly connects from the Upconverter RF Output
BNC Jack J23, through a cable, to the PA RF Input BNC Jack J24, located on the rear of the
exciter/amplifier chassis assembly.
4.5.5 (A4) Coupler Board Assembly
(Appendix B)
The UHF coupler board assembly
provides a forward and reflected power
samples of the output to (A5) the
amplifier control board where it connects
to the input of the overdrive-protection
circuit.
The RF input to the UHF coupler
assembly, from the 250 Watt UHF
amplifier module, connects to SMA jack
J1. The RF is connected by a stripline
track to the SMA type connector RF
Output jack J2. A hybrid-coupler circuit
picks off a power sample that is
connected to SMA type connector jack J3
as the forward power sample. Another
power sample is taken from the coupler
circuit that is connected to SMA type
connector jack J6 as the reflected power
sample. Two 50O terminations, used as
dissipation loads, connect to the reject
and reflected ports, J5 and J4, of the
coupler.
4.5.6 (A5) Amplifier Control Board
(Appendix B)
The amplifier control board provides LED
fault and enable indications on the front
panel of the module and also performs
the following functions: overdrive
cutback, when the drive level reaches the
amount needed to attain 110% output
power; and overtemperature, VSWR, and
overdrive faults. The board also provides
connections to the LCD Display for
monitoring the % Reflected Power, %
Output Power, and the power supply
voltage.
Page 1
U4, located upper center of page, is an in
circuit microcontroller. The controller is
operated at the frequency of 3.6864 MHz
LX Series, Rev. 0
using crystal Y1. Programming of this
device is performed through the serial
programming port J2. U4 selects the
desired analog channel of U1 through the
settings of PA0-PA3. The outputs of Port A
must be set and not changed during an
analog input read of channels PA5-PA7.
PA4 of U4 is a processor operating LED
that monitors the +/-12 VDC. PA5 is used
to monitor the +12VDC supply to the
board. PA6 is the selected channel of
analog switch U1. PA7 is connected to a
via, V10, for future access.
U6 is a serial to RS-485 driver IC. U7 is a
watchdog IC used to hold the
microprocessor in reset, if the supply
voltage is less than 4.21 VDC. U7
momentarily resets the microcontroller if
Pin 6 (!ST) is not clocked every second. A
manual reset switch is provided but should
not be needed.
Upper left corner U3 is used to determine
where the amplifier control board is
located. The eight inputs come from the
main amp connector and are used to set
the SCADA address of the controller. Pullup resistors set a default condition of logic
high.
U5 below U3 is used for getting digital
input information of the board. Page two
has several monitoring circuits that provide
information on the amplifier’s status. Many
of these circuits automatically shut down
the amplifier if a specific fault occurs.
U8 below U5 is used to control four board
mounted status LEDs. A FET is turned On
to shunt current away from the LED to turn
it Off. U9 below U8 is used to enable
different features within the software.
Actual use is to be determined.
Page 2
4-23
UHF Analog Driver/Transmitter
In the lower right corner are voltage
regulator circuits. U22 should allow for
0.14 amps of power using its 92 C/W
rating if Ta = 60°C max and Tj = 125°C
max 0.26 amps can be obtained from
U22 if the mounting pad is 0.5 square
inches. The controller will not need this
much current.
U23 and U24 are low drop out +5 VDC,
voltage regulators with a tolerance
greater than or equal to 1%. 100mA of
current is available from each device but
again the controller will not need this
much current.
In the upper left section are circuits with
U12 and U13. U12 is used to generate a
regulated voltage that is about 5 volts
less than the +32 VDC supply,
approximately +26.25 VDC. When the
+32 VDC supply is enabled, the circuitry
around U13B is used to provide gate
voltage to Q10 that is 5 volts greater
than the source pin of this FET. The gate
of Q10 can be turned Off by any one of a
few different circuits.
U10A is used to turn Off the gate of Q10
in the event of high current in amplifier
#1. At 0.886 VDC the current to
amplifier #1 should be greater than 5
Amps. U11B is used to turn off the Q10
FET, if high current is detected in
amplifier #2. U11A is used to turn off
the Q10 FET, if high current is detected
in amplifier #3. With 2.257 VDC at Pin 5
of U11B or Pin 3 of U11A, the voltage
output of current sense amplifier U17 or
U18 at high current shut down should be
greater than 15 Amps.
U14B is used to turn Off the gate of Q10
in the event of high power supply
voltage, approximately +35.4 VDC.
U14A is used to keep the FET disabled in
the event of low power supply voltage,
approximately +25.4 VDC.
Chapter 4, Circuit Descriptions
current monitoring sections of the board.
R67, R68 and R69 are 0.01O/5W 1%
through hole resistor is used for monitoring
the current through several sections of the
amplifier. The voltage developed across
these resistors are amplified for current
monitoring by U16, U17 or U18. The
LT1787HVCS8 precision high side current
sense IC amplifier accepts a maximum
voltage of 60 VDC. The 43.2 kO resistor
from pin 5 to ground sets the gain of the
amplifier to about 17.28. This value is not
set with much accuracy since the
manufacturer internally matches the
resistors of this part but their actual
resistance value is not closely defined. A
trimming resistor is suggested to give a
temperature stability of –200 ppm/C, but
instead the microcontroller will determine
the exact gain of the circuit and use a
correction factor for measurements.
Circuit loading components are located in
the lower portion of each current
monitoring circuit. These components
allow for short duration high current
loading of the supply. By measuring the
current through the sense resistor with and
without the additional four 30.1 O 1%
resistors. For very short duration pulses, a
1206 resistor can handle up to 60 watts.
The processor requires 226 uSec per
conversion. A supply voltage of +32 VDC
will pass 1.06 amps + 1% through the load
resistors.
A6 is a temperature sensor thermistor
that is used to monitor the temperature of
the module's heat sink. It connects to J6
pins 1 & 2 on the board wand is wired to
the comparator IC U10B. If the
temperature increases above 75°C the
output will go Low that is used as a
temperature fault output, which generates
a Fault alert at U15A and disables
Amplifier #1.
Aural, Visual/Average and Reflected power
detector sections of the board.
Current monitoring sections of the board.
Page 3
The ICs U16, U17 and U18 along with
associated components set up the
A Forward Power Sample enters the board
at SMA Jack J3 and is split. One part
LX Series, Rev. 0
4-24
UHF Analog Driver/Transmitter
connects to J4 on the board that is
cabled to J1, the SMA Forward Power
Sample Jack, located on the front panel
of the assembly. The other part of the
split forward power sample is detected by
CR17 and the DC level amplified by
U25A. The output of U25A at pin 1 is
split with one part connected to the Aural
Power sample, which is not used in this
digital transmitter. The other split output
connects to U265A that is part of the
Forward Average Power circuit. The
detected level is connected to L4 that is
part of an intercarrier notch filter circuit
that is tuned to eliminate the 4.5 MHz
aural intercarrier, if present. The
Average power sample is amplified by
U26D and connected through the
average calibration pot R166 to U26C.
The output of U26C is connected to the
comparator IC U26B that has Aural Null
and Offset Null, if present in the system,
connected to the other input. The output
Average Forward power level connects to
J9 pin 2 of the board.
A Reflected Power Sample enters the
board at SMA Jack J5 and is detected by
CR20 and the DC level amplified by
U28B. The output of U28B at pin 7 is
connected through the reflected
calibration pot R163 to U28C. The
output is split with one part connected to
J9 pin 5, the Reflected Power Output
level of the board. The other part of the
split from U28C connects to the
comparator IC U28D that has a reference
LX Series, Rev. 0
Chapter 4, Circuit Descriptions
level connected to the other input. If the
reflected level increases above the
reference level a low output is produced
and connected to the Reflected Power
Shutdown circuit at CR28. The low shuts
off Q14 causing pin 3 to go high that is
connected to the inverter U15C. The
output of U15C goes low producing a
Reflected Power Fault that is connected to
an output of the board, the Fault Alert
circuit and also shuts down Amplifier #1.
Gain of the power measurements is
completed through software. Only the
Aural Null and Offset Null need to be done
through front panel pots.
This completes the description of the Power
Amplifier Module Assembly that is used
with 10W to 100 W transmitters.
4.5.7 (A9) Bandpass and (A10) Trap
Filter
The RF Output of the Tray is connected to
(A9) the Bandpass Filter and then to (A10)
the UHF Trap Filter Assembly. Both filters
are tuned to provide high out of band
rejection of unwanted products.
The
filtered RF Output at the “N” connector jack
(J2) of the Trap Filter is cabled to the
Antenna for your System.
This also completes the description for the
entire Exciter/Amplifier chassis assembly.
4-25
UHF Analog Driver/Transmitter
Chapter 5, Detailed Alignment Procedures
Chapter 5
Detailed Alignment Procedures
This transmitter was aligned at the
factory and should not require additional
adjustments to achieve normal operation.
After removal of the failed module, slide
the replacement module in place and
make certain it connects to the
backplane board. If the replacement
module is a PA Module replace the two
cables on the rear of the
exciter/amplifier chassis assembly. If
the replacement module does not slide
in easily, verify it is properly aligned in
the nylon tracks, located on both the top
and bottom of the module.
This transmitter takes the baseband
audio and video inputs or, if the
(Optional) 4.5-MHz composite input kit is
purchased, either a single composite
video + 4.5-MHz input or separate
baseband video and audio inputs, and
converts them to the desired UHF On
Channel RF Output at the systems output
power level.
Note: Each Module has an assigned slot
and will not fit properly in the incorrect
slot. Do not try to place a Module in the
wrong slot as this may damage the slot
or the connectors on the backplane
board.
The exciter/amplifier of the LX Series
transmitter is of a Modular design and
when a Module fails that module needs to
be changed out with a replacement
module. The failed module can then be
sent back to Axcera for repair. Contact
Axcera Customer Service Department at
724-873-8100 or fax to 724-873-8105,
before sending in any module.
Each module has the name of the
module on the front, bottom for
identification and correct placement.
The Modules are placed in the unit from
left to right; (1) Blank panel, (2)
Modulator (for analog transmitters) or a
Blank panel for a Translator or digital
transmitter, (3) IF Processor, (4)
Upconverter, (5) Controller/Power
Supply and (6) Power Amplifier.
5.1 Module Replacement
Module replacement on the LX series
products is a relatively simple process.
All modules plug directly into the
backplane board except for the power
amplifier module, and in higher power
units, the power supply and power
amplifier modules, that plug into a blind
mating connector. To replace a module,
refer to the following procedure.
5.1.1 Initial Test Set Up
Check that the RF output at the coupler
is terminated into a dummy load of at
least 100 watts. While performing the
alignment, refer to the Test Data Sheet
for the transmitter and compare the final
readings from the factory with the
readings on each of the modules. The
readings should be very similar. If a
reading is way off, the problem is likely
to be in that module.
Loosen the two grip lock connectors,
located on the front panel, at the top
and bottom of the module,
counterclockwise until the module
releases. The Modulator, IF Processor,
Upconverter and Controller/Power
Supply can then be gently pulled from
the unit. There are two cables
connected to the rear of the Power
Amplifier Module in the exciter/amplifier
chassis assembly. These two cables
must first be removed before the PA
module will slide out.
LX Series, Rev. 0
Switch On the main AC for the system.
5-1
UHF Analog Driver/Transmitter
Chapter 5, Detailed Alignment Procedures
5.2 LX Series Exciter/Amplifier
Chassis Assembly
following details the meaning of each
LED:
This transmitter operates using the
baseband audio and video inputs or, if
the (optional) 4.5-MHz composite input
kit is purchased, either a single
composite video + 4.5-MHz input or
separate baseband video and audio
inputs.
AURAL UNLOCK (DS5) – Red Indicates
that 4.5 MHz Aural IF is unlocked from
the Nominal 45.75 MHz visual IF.
On the LCD Display, located on the
Controller/Power Supply Module, in
Transmitter Set-Up, push the button to
switch the transmitter to Operate. The
check of and the setup of the Audio and
Video input levels are completed using
the LCD Display and the front panel
adjustments on the Modulator assembly.
The level of the RF output includes
adjustments of the drive level to the
Power Amplifier and the adjustment of
the linearity and phase predistortion to
compensate for any nonlinear response
of the Power Amplifier. The adjustments
are located on the front panel of the IF
Processor module.
AUDIO OVER DEVIATION (DS4) – Red
Indicates that the input Audio level is too
high. (±75 kHz max)
VISUAL UNLOCK (DS6) – Red Indicates
that the Nominal 45.75 MHz visual IF is
unlocked from the 10 MHz reference.
VIDEO LOSS (DS1) – Red Indicates that
the input Video level is too low.
OVER MODULATION (DS3) – Red
Indicates that the input Video level is too
high.
ALTERNATE IF (DS7) – Red Indicates
that an external Nominal 45.75 MHz IF is
not present to the modulator.
10 MHz PRESENT (DS2) – Red Indicates
that an external 10 MHz reference is not
present to the modulator.
Modulator Module Assembly
NOTE: Not present in a Translator
systems.
Look at the front panel LCD meter on the
Control/Power Supply Module Assembly.
Set the LCD screen to the Modulator
Details video output level screen, the
screen indicates active video from 0 to 1
Vpk-pk. The normal video input level is 1
Vpk-pk on the front panel screen. If this
reading is not at the proper level, the
overall video level can be changed by
adjusting the VIDEO LEVEL control R42
on the front panel of the Modulator to the
1 Vpk-pk level on the front panel screen.
The Modulator Assembly has adjustments
for video levels and audio modulation
levels, and other related parameters.
Connect an NTSC baseband video test
signal input (1 Vpk-pk) to the transmitter
video input jack J7 on the rear of the
tray. Jacks J7 and J17 are loop-through
connected; the J17 jack can be used as a
video source for another transmitter.
Connect a baseband audio input (+10
dBm) to the balanced audio input
terminal block TB02-1 [+], TB02-2 [-],
and TB02-3 [ground] or, if
stereo/composite audio is provided,
connect it to BNC jack J3, the composite
audio input jack.
NOTE: An NTSC or FCC composite signal
should be used for video metering
calibration.
Switch the LCD display to the Modulator
Details screen that indicates the AUDIO
DEVIATION (modulation level) of the
signal up to 75 kHz.
Verify that all LEDs located on the front
panel of the Modulator are Green. The
LX Series, Rev. 0
5-2
UHF Analog Driver/Transmitter
Chapter 5, Detailed Alignment Procedures
MONO SET UP: The modulator was
factory set for a ±25-kHz deviation with
a mono, balanced, audio input of +10
dBm. If the reading is not at the correct
level, adjust the MONO Audio Gain pot
R110, located on the front panel of the
modulator, as necessary, to attain the
±25-kHz deviation on the front panel
screen.
•
DS4 (Mute) – Indicates that a Mute
command is present to the system.
Switch the transmitter to Standby. The
ALC is muted when the transmitter is in
Standby. To monitor the ALC, preset R3,
the manual gain adjust pot, located on
the front panel of the Upconverter
module, fully CCW. Move switch SW1,
Auto/Man AGC, on the front panel of the
Upconverter module, to the Manual
position. Place the transmitter in
Operate. Adjust the ALC GAIN pot on the
front panel of the IF Processor to obtain
100% output power on the LCD Display
mounted on the Controller/Power Supply
in the ALC screen. Move the MAN/AUTO
ALC switch back to Auto, which is the
normal operating position.
STEREO SET UP: The modulator was
factory set for a ±75-kHz deviation with
a stereo, composite, audio input of 1
Vpk-pk. If this reading is not correct,
adjust the STEREO Audio Gain pot R132,
located on the front panel of the
modulator, as necessary, for the ±75kHz deviation.
SECONDARY AUDIO SET UP: NOTE:
Remove any stereo or mono audio
modulation input to the transmitter
during the set up of the secondary audio.
The modulator was factory set for a ±15kHz deviation with a secondary audio
input of 1 Vpk-pk. If this reading is not
correct, adjust the SAP/PRO Audio Gain
pot R150, located on the front panel of
the modulator, as necessary, for the
±15-kHz deviation.
To adjust the AGC Cutback setting, raise
the output power of the transmitter to
120%. Adjust R2, AGC Cutback, located
on the front panel, CCW until the LED
DS1, AGC Cutback, just starts to flash.
Return the output power of the
transmitter to 100%.
5.2.1 Linearity Correction
Adjustment
IF Processor Module Assembly
As shipped, the exciter was preset to
include amplitude and phase predistortion. The pre-distortion was
adjusted to approximately compensate
the corresponding non-linear distortions
of the Power Amplifier.
Verify that all red LEDs located on the IF
Processor front panel are extinguished.
The following details the meaning of each
LED when illuminated:
•
DS1 (input fault) – Indicates that
either abnormally low or no IF is
present at the input of the IF
Processor module.
NOTE: On the IF processor board inside
the module the correction enable/disable
jumper W12 on J30 will be in the Enable
position, on pins 2 & 3.
•
DS2 (ALC fault) – Indicates that the
ALC circuit is unable to maintain the
signal level requested by the ALC
reference. This is normally due to
excessive attenuation in the linearity
signal path or the IF phase corrector
signal path, or that switch SW1 is in
the Manual ALC Gain position.
Set up a spectrum analyzer with 100
kHz resolution bandwidth and 100 kHz
video bandwidth to monitor the
intermodulation products of the RF
output signal of the Power Amplifier.
LX Series, Rev. 0
A typical red field spectrum is shown in
Figure 5-1. There are three Linearity
Corrector stage adjustments located on
the front panel of the IF Processor
5-3
UHF Analog Driver/Transmitter
Chapter 5, Detailed Alignment Procedures
Module. The adjustments are threshold
settings that are adjusted as needed to
correct for any amplitude or phase
intermod problems. Adjust the top
linearity correction adjustment R211
threshold cut in for the in phase
amplitude distortion pre-correction that
is needed. Next adjust the middle
linearity correction adjustment R216
threshold cut in also for the in phase
amplitude distortion pre-correction that
is needed. Finally adjust the bottom
linearity correction adjustment R231
threshold cut in for the quadrature
phase distortion pre-correction that is
needed. The above pots are adjusted
for the greatest separation between the
peak visual carrier and the intermod
products. NOTE: These pots affect
many other video parameters, so care
should be taken when adjusting the
linearity correction.
Figure 5-1. Typical Red Field Spectrum
5.2.2 Frequency Response Delay
Equalization Adjustment
bottom frequency response equalizer pot,
located on the front panel of the IF
Processor Module, for the best depth of
frequency response correction at 43.5
MHz.
The procedure for performing a
frequency response delay equalization
adjustment for the transmitter is done at
IF and is described in the following steps:
After the three delay attenuation
equalizers have been adjusted, fine tune,
as needed, for the best frequency
response across the channel.
The center frequency for the first stage is
45 MHz. Adjust R103, the top frequency
response equalizer pot, located on the
front panel of the IF Processor Module,
for the best depth of frequency response
correction at 45 MHz.
5.2.3 Calibration of Output Power
and Reflected Power of the
transmitter
The center frequency for the second
stage is 42 MHz. Adjust R106, the
middle frequency response equalizer pot,
located on the front panel of the IF
Processor Module, for the best depth of
frequency response correction at 42 MHz.
Note: Perform the following
procedure only if the power
calibration is suspect.
Switch the transmitter to Standby and
place the Upconverter into Manual Gain.
Preset R205, the aural null pot on the
Amp Control board, fully CCW. Adjust
R204, the null offset pot on the Amp
The center frequency for the second
stage is 43.5 MHz. Adjust R274, the
LX Series, Rev. 0
5-4
UHF Analog Driver/Transmitter
Chapter 5, Detailed Alignment Procedures
Control board, for 0% visual output.
Perform the following adjustments with
no aural present by removing the aural
IF carrier jumper on the back of the
chassis assembly. Connect a sync and
black test signal to the video input jack
of the test modulator. Switch the
transmitter to Operate.
R163 on the power amplifier module to a
10% reading. A reflected power fault
should be present on the LCD Display.
Reconnect the load to J4 in the module.
After this calibration is completed, move
switch SW1 on the upconverter module
to the Automatic AGC position. This is
the normal operating position for the
switch. Adjust the ALC pot on the IF
Processor is needed to attain 100%
output power. Switch to Manual Gain
(Manual AGC) and adjust the Manual
Gain pot for 100 % output power.
Switch the upconverter back to
Automatic AGC.
Next, set up the transmitter for the
appropriate average output power level:
Example is for 100 Watt Transmitter.
•
Sync + black 0 IRE
setup/wattmeter=59.5 watts
•
Sync + black 7.5 IRE
setup/wattmeter=54.5 watts
The Transmitter is now aligned,
calibrated, and ready for normal
operation.
Note: The transmitter must have 40
IRE units of sync.
This completes the detailed alignment
procedures for the LX Series transmitter.
Adjust R202, visual calibration, on the
Amp Control board for 100% on the front
panel LCD display in the % Visual Output
position.
If a problem occurred during the
alignment, help can be found by calling
Axcera field support at 724-873-8100.
5.3 Alignment Procedure for the
Bandpass Filter Assembly
With the spectrum analyzer set to zero
span mode, obtain a peak reference on
the screen. Reconnect the aural carrier
jumper on the rear of the chassis
assembly. Turn the power adjust pot on
the front panel until the original peak
reference level is attained. Adjust R203
for a 100% aural power reading. Switch
to the Visual Output Power position and
adjust R205 (aural null pot) for 100%
visual power.
The Bandpass Filter Assembly is tuned to
reject unwanted distortion products
generated when the signals are diplexed
and also during the amplification process.
The Bandpass Filter is factory tuned to
the proper bandwidth and should not
need tuned. If you think tuning is
needed consult Axcera Field Support
Department before beginning the
adjustment.
To calibrate the reflected output power
reading of the transmitter. Reduce
manual gain pot R3 to a 10% reading on
the LCD front panel display in the %
Output Power position. Place the
transmitter in Standby. Remove the PA
Module Sled. Remove the load from J4
on the (A4) Directional Coupler Board
and switch the LCD Display screen to the
Reflected Output Power position.
Reinstall the PA Module. Switch the
transmitter to operate. Adjust the
reflected power calibration adjust pot
LX Series, Rev. 0
The Traps are labeled with their Center
Frequency relative to the Frequency of
the Carrier. (For Example: The Traps
labeled -4.5 MHz are tuned for a Center
Frequency of 4.5 MHz Lower than the
Frequency of the Visual Carrier.)
The Trap Sections are Reflective Notches,
adjustable across the entire UHF
Frequency Band. The electrical length of
5-5
UHF Analog Driver/Transmitter
Chapter 5, Detailed Alignment Procedures
the Outer Sleeve and the Center Rod of
the Notch can be adjusted to tune the
Notch Frequency. The Depth of the
Notch is set by the gap between the
Center Conductor of the Trap Section and
the Center Conductor of the Main Line.
Tight Coupling makes a Deep Notch,
while Loose Coupling makes a Shallow
Notch.
Center Conductor with an Allen Wrench
and move it Deeper for a Lower
Frequency Notch or out for a Higher
Frequency Notch. These adjustments
must both be made to change the Notch
Frequency. Moving only the Center
Conductor or the Outer Conductor will
effect the Notch Depth in addition to the
Center Frequency. The variable that is
being adjusted with this procedure is the
length of the Center Conductor inside the
Trap Filter. The gap between the Trap
and the Main Line should not be changed.
Moving only the Inner or the Outer
Conductors by itself will effect the Gap
and the Notch depth.
NOTE: The Trap Sections have been
factory tuned and should not need major
adjustments. The Frequency, relative to
Visual Carrier, that the Trap is tuned to is
marked on the Notch. Fine Tuning of the
Notches Center Frequency can be
accomplished with the Tuning Bolts
located on the side of the Filter Section.
Loosen the nut locking the Bolt in place
and adjust the Bolt to change the
Frequency of the Notch. Monitor the
output of the Transmitter with a
Spectrum Analyzer and Null the
Distortion Product with the Bolt.
To effect the Notch Depth Only, both
sections will have to be moved. The
Notch Depth is controlled by the Gap
between the Center Conductor and the
Trap Section. This Gap also has an effect
on the Center Frequency. To Deepen the
Notch, Shorten the Outer Conductor and
pull the Center Conductor Out until the
Notch is back in the same place. Move
the Sections in the opposite direction to
make a Shallow Notch.
Red Field is a good Video Test Signal to
use to see the out-of-band Products.
Tighten the nut when the tuning is
completed. Hold the bolt in place with a
screwdriver as the nut is tightened to
prevent it from slipping.
After tuning has been completed, tighten
the Clamp and the Allen Screws which
hold the Conductors. Use the Fine
Tuning Bolts to bring the Frequency In.
The Final Tuning Adjustments should be
completed with the Transmitter driving
the Output Trap Filter for at least one
hour to allow for warm-up drift.
For major tuning, such as changing the
Notch Depth or moving the Notch
Frequency more than 1 MHz, the Outer
Conductor and the Center Conductor of
the Trap Section must both be moved.
This requires an RF Sweep Generator to
accomplish. Apply the Sweep signal to
the Input of the Trap Filter and monitor
the Output. Loosen the Clamp holding
the Outer Conductor in place and make
the length longer to Lower the frequency
of the Notch or shorter to Raise the
frequency of the Notch. Loosen the
LX Series, Rev. 0
This completes the Alignment Procedure
for the Bandpass Filter Assembly and the
exciter/amplifier assembly of the LX
Series Transmitter.
5-6
APPENDIX A
LX SERIES ANALOG
SYSTEM SPECIFICATIONS
Innovator LX (Preliminary)
Low Power Transmitter 10W-6kW
Designed to provide broadcasters with a product that will meet their needs like
no other solution on the market, this new low to medium power transmitter
line uses the latest LDMOS devices for broadband operation across the entire
UHF band. This allows users to minimize spare parts stock, which is especially
important to group owners and networks, and also enables simple and
inexpensive channel changes.
The very compact and completely modular design uses a chassis/backplane
configuration with parallel amplifier and power supply modules that can be
removed and replaced while the transmitter is on the air. Additionally, the
Innovator LX series was designed to be field upgradable to digital operation.
Configurations are available in power levels from 10 watts to 6 kilowatts
analog and up to 3 kilowatts DTV, and all are manufactured in the USA by
Axcera - The RF Experts.
Innovator LX (Preliminary)
Low Power Transmitter 10W - 6kW
Visual Performance
Visual Performance (continued)
Frequency Range
470 to 806 MHz
Carrier Stability (Transmitters)
Standard
±1 kHz
Optional
±350 Hz
w/PFC
±1Hz
Frequency Translation Stability (Translators)
Standard
±1 kHz
Optional
±350 Hz
w/PFC
±1Hz
Regulation of RF Output Power
3%
Output Variation (Over 1 Frame)
2%
Sideband Response
-1.25 MHz and below
-20 dB
-0.75 to -0.5 MHz
+0.5 db, -2 dB
-0.5 to +3.58 MHz
±0.5 dB
+3.58 MHz to +4.18 MHz
+0.5, -1.0 dB
Freq Response vs. Brightness
±0.5 dB
Visual Modulation Capability
1%
Differential Gain
5%
Incidental Phase Modulation
±3°
Linearity (Low Frequency)
5%
Differential Phase
Signal-to-Noise Ratio
2t K-Factor
Noise Factor (Translators)
w/Input Preamp
Input Dynamic Range (Translators)
w/Input Preamp
Env. Delay (Transmitters)
Video Input (Transmitters)
Harmonics
Intermodulation Products
Spurious (›3 MHz from channel edge)
100W and lower
Greater than 100W
Aural Performance
Frequency Deviation Capability
(Transmitters)
Distortion
FM Noise
AM Noise
Aural to Visual Separation
±3°
55 dB
2%
5 dB (Max)
3 dB (Max)
-60 dB to
-15 dBm
-75 dBm
to -30 dBm
Per FCC Standard
75 ohms
(Loop through)
-60 dB or better
-52 dB or better
±75 kHz
0.5%
-60 dB
-55 dB
4.5 MHz
± 100Hz
Composite Audio Input (Multi-channel sound)
(Transmitters)
Input Level
1V peak,
nominal
75 ohms,
unbalanced
Input Impedance
Frequency Range
±0.1 dB response
±0.5 dB response
Monaural Audio Input (Transmitters)
Input Level
Input
-50dB or better
-60dB or better
Freq Range (±0.5 dB resp.)
Pre-emphasis
Subcarrier Input (Transmitters)
Input Level
Input Impedance
Freq Range (±0.5 dB resp.)
50 Hz to 50 kHz
30 Hz to 120 kHz
0 to +10 dBm
600 ohms,
balanced
30 Hz to 15 kHz
75µs
1V peak,
nominal
75 ohms,
unbalanced
20 kHz to
120 kHz
General
Model Number*
LU10Ax LU100Ax
LU250Ax
LU500Ax
LU1000Ax
LU2000Ax
LU3000Ax
LU4000Ax
LU5000Ax
LU6000Ax
Power Output (Watts)
Visual (Peak)
Aural (Avg.)
10
100
10
Output Connector
Power Consumption (Watts)
250
675
250
25
7/ ” EIA
1100
500
50
7/ ” EIA
1900
1000
100
7/ ” EIA
3500
2000
200
7/ ” EIA
6700
3000
300
31/8” EIA
10,250
4000
400
31/8” EIA
13,500
5000
500
31/8” EIA
16,700
6000
600
31/8” EIA
19,900
Input Power
Line Voltage (Volts)
Power Requirements
117/230 ±10%
Size (H x W x D)
230 ± 10%
Single Phase, 50 or 60 Hz
8.75”x19”x23”
55”x22”x34”
76”x22”x34”
76”x44”x34”
(Chassis Only)
Weight (lbs.)
45
45
340
360
Operational Temperature Range
400
550
700
1030
1180
1330
0 to +50°, derate 2°C/1000 ft.
Maximum Altitude 3
8500 feet (2600m) AMSL
Operational Humidity Range
0% to 95% non-condensing
RF Load Impedance
50 Ω
* For transmitters use “T” suffix, translators use “L” suffix (ex. LU100AT - 100W Transmitter)
Specifications published here are current as of the date of publication of this document. Because we are continuously improving our products, Axcera reserves the right to
change specifications without prior notice. At any time, you may verify product specifications by contacting our office. Axcera views it’s patent portfolio as an important
corporate asset and vigorously enforces its patents. Products or features contained herein may be covered by one or more U.S. or foreign patents.
0311R3
© 2003 AXCERA
All Rights Reserved
An Equal Opportunity Employer
A Platinum Equity Company

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