LX Series Digital
Chapter 2, Amplifier Assembly Description,
Power Amplifier Assembly
Maintenance & Remote Control Connections
Volume 2, Rev. 1
2-8
Table 2-2: Typical LX Series Power Amplifier Chassis Assemblies
ASSEMBLY
DESIGNATOR
ASSEMBLY NAME
PART NUMBER
500W/1 kW (250W/500W Digital) Chassis
Assembly
1303953
A3 & (Opt A6 & A13)
Power Amplifier Assembly, 250W (125W
Digital)
1302868
Power Supply Assembly
1302863(2kW)
1306971(1kW)
Opt A5
2 or 4 Way Splitter Assembly
1303567 (2 Way)
1303347 (4 Way)
A11 Coupler
Assembly
450029
A4 or A44
Dual Peak Detector Board
11159965
2.1.3 Power Amplifier Module
Assembly, 250 Watt, 125W Digital
(1302868; Appendix B)
The 125 Watt Power Amplifier Module
Assembly is made up of (A6) an Amplifier
Control Board (1303682, 1301962 or
1303702), (A1) a UHF Phase/Gain Board
(1303213), (A2) a 150 Watt Driver Pallet
Assembly (1303293), (A3 & A4) two RF
Module Pallets, Philips (1300116), and
(A5) a 2-Way Combiner Board
(1303208).
The Power Amplifier Module contains
Broadband LDMOS amplifiers that cover
the entire UHF band with no tuning
required. Each module amplifies the RF
to a nominal 300W output power. The
Power Amplifier assembly is used to
amplify the RF output of the
Transmitter/Exciter Driver. A cable,
located on the rear chassis, connects the
RF output from the Exciter/Driver at J25
to J200 the RF input to the PA Assembly.
This module contains RF monitoring
circuitry for both an analog and a digital
system. Control and monitoring lines to
the Power Amplifier module are routed
through the floating blind-mate
connector of the Control &
Monitoring/Power Supply module.
The Transmitter/Exciter Driver Power
Amplifier module and any External
Power Amplifier modules contain the
same control and monitoring board.
This board monitors RF output power,
RF reflected power, the current draw of
amplifier sections, the supply voltage,
and the temperature of the PA heat sink.
The RF power detector circuit outputs
vary with operating frequency. These
circuits must be calibrated at their
intended operating frequency. The
following front panel potentiometers are
used to set the Power Amplifier
Calibrations.
R201 Reflected Power Cal
R202 Forward Power Cal
R204 Meter
Offset
Zero
In digital systems, the Forward power of
an Exciter Driver Power Amplifier and
the Forward power of any external
amplifier, is reported by the system
Control Monitoring module.
If the Control Monitoring module is
monitoring a 5-50 Watt Digital 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
