7.3.5
OUTPUT POWER ADJUSTMENT
The output of the filter is sent into an adjustable gain stage formed by U3A. This varies the output
level, which determines the system transmission power (10W, 3W or 1W output of the power amplifier
stage). Potentiometer R23 adjusts the nominal output voltage of the transmitter. It is set to achieve
10W output with switches U6A, U6B and U6C open. In systems which require a “reserve” 1\10
th
power output, U6A may be closed to attenuate the output signal to achieve the reduced power. This
power reduction can be varied by R18 if jumper J2 is in the “VAR” position. If analog switch U6C is
closed, the output power will drop to 3W. If both U6B and U6C are closed, the output power will drop
to 1W.
All module functions are controlled by Field Programmable Gate Array (FPGA) U7. The FPGA reads
the on board configuration switches and control signals coming from other modules, and controls the
local hardware and indicators. It also computes the phase step required to generate the desired output
frequency.
7.4
CONTROLS AND INDICATORS
Figure 7-4 shows the locations of all controls and indicators on the transmitter module. These controls
and indicators are described in Table 7-1. LEDs DS1 through DS9 are visible with the module
installed in the chassis. All other controls are only accessible when the module is removed from the
chassis or is on a card extender (RFL Part No. 9547-1870).
Table 7-1. Controls and indicators, RFL 9785 Transmitter Module
Component
Designator
Name/
Description
Function
DS1
Carrier Enabled LED
Indicates the carrier is being generated
DS2
Frequency 3 LED
The carrier is set for shift up frequency
DS3
Frequency 2 LED
The carrier is set for center frequency
DS4
Frequency 1 LED
The carrier is set for shift down frequency
DS5
Power 3 LED
The system’s output power is 10W
DS6
Power 2 LED
The system’s output power is 3W
DS7
Power 1 LED
The system’s output power is 1W
DS8
Reserve LED
The system is transmitting at reserve power (1/10 of normal power)
DS9
Voice Enabled LED
The voice signal is being AM modulated onto the carrier
J1
Test Connector
For factory use only
J2
Reserve level jumper
Variable or 10%
R18
Potentiometer
Used to vary the reserve level
R23
Potentiometer
Sets the module’s nominal output level
SW1-SW2
Switch bank for shift down freq.
Sets the desired shift down frequency
SW3-SW7
Switch bank for center frequency
Sets the desired center frequency
SW8-SW9
Switch bank for shift up freq.
Sets the desired shift up frequency
TP1
Test point
Digital ground
TP2
Test point
Signal ground
TP3
Test point
Oscillator out (Output of DDS following filter)
TP4
Test point
Carrier out (Final output of module)
TP5
Test point
Voice in (Audio input signal in systems having the voice option)
TP6 Test
point
Reference
TP7
Test point
+5Vdc (Digital)
TP8
Test point
+5Vdc (Analog)
RFL 9785
RFL Electronics Inc.
April 25, 2005
7-5
(973) 334-3100