User Manual

UHF Analog Driver/ Transm it ter Chapter 2, Syst em Descript ion
& Rem ot e Cont rol Connect ions
LX Series, Rev. 0 2- 10
Assem bly (1301949), an Am plifier
Control Board (1301962), a 1 Watt
Module Assem bly (1302891) and a TFS
40W UHF Module (1206693).
The Driver Power Am plifier Module
contains Broadband LDMOS am plifiers
that cover the entire UHF band with no
tuning required. They am plify the RF to
the power level, 7 Watts Peak of Sync is
maxim um , that is needed to drive the
external amplifiers to the output power
level of the transmitter.
The Driver Power Am plifier is used to
am plify the RF output of the
Upconverter m odule. A cable, located on
the rear chassis, connects the RF output
from the LO/ Upconverter at J23 to J24
the RF input to the driver PA Assem bly.
This module contains RF m onitoring
circuitry for both an analog and a digital
system . Control and monitoring lines to
the Driver Power Am plifier m odule are
routed through the floating blind- m ate
connector of the Control &
Monitoring/ Power Supply module.
The Driver Power Am plifier m odule and
any External Amplifier m odules contain
the sam e control and monitoring board.
This board monitors RF output power,
RF reflected power, the current draw of
am plifier sections, the supply voltage,
and the temperature of the PA heat sink.
The RF power detector circuit outputs
vary with operating frequency. These
circuits m ust be calibrated at their
intended operating frequency. Front
panel adjustm ent potentiom eters are
used to calibrate the following:
Table 2: Power Am plifier Calibration
Adjustm ents in Analog System s
R201 Reflected Power Cal
R202 Visual / Forward Power Cal
R203 Aural Power Cal
R204 Visual Offset Zero
R205 Aural Null
In analog systems, the Aural power of
an Exciter Driver Power Am plifier and
the Aural power of any external PA
am plifiers will not be reported by the
system Control Monitoring module.
Additionally the Visual power of these
am plifiers, is reported as Forward Power
just like in digital systems. In analog
system s, aural and visual power will only
be reported for the final system RF
output.
In digital system s, the Forward power of
an Exciter Driver Power Am plifier and
the Forward power of any external
am plifiers, are reported by the system
Control Monitoring module.
If the Control Monitoring module is
monitoring a 10- 100 Watt Transmitter,
system power is m easured in the Power
Am plifier m odule. 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. I n system s of output
power greater than 100 Watts, system
power is monitored by an external
module that is connected to TB31. I n
this configuration switches SW1 on the
control board m ust be set off.
The Forward Power of the Exciter Driver
Power Amplifier m odule is routed to the
Upconverter m odule as AGC # 1. A
system over- drive condition is detected
when this value rises above 0.9 VDC.
When an over- drive condition is
detected, the Upconverter m odule
reduces its RF output level.
For values less than 0.9 VDC, the
Upconverter uses this voltage for
autom atic gain.