Product Drawings Chapter 3

AE02B-A3659 Rev -- FUNCTIONAL DESCRIPTION
Document use is restricted to that described on cover 3-4
3.2.3.2 UPCONVERTER
The upconverter board mixes the filtered 45 MHz IF with a signal from the synthesizer and outputs the
same frequency that was input to the downconverter. The upconverter consists of a mixer, gain stage, and
filter. The DC current draw of each gain stage is monitored by a window comparator. The window
comparator indicates a fault, if the gain stage has an open or short condition.
3.2.3.3 SYNTHESIZER
The synthesizer board consists of a synthesizer circuit that is driven by a reference oscillator and distribution
amplifiers. The synthesizer operating frequency is programmed from the Control/Distribution module. The
forward channel frequencies are set with a computer that has Andrew designed frequency control software
installed on it. This software is a Microsoft Windows 95/98/NT application that allows the operator to input
the desired channel frequency. The Control/Distribution module converts the operator's input to the
appropriate frequency command for the synthesizer. The output of the synthesizer is divided into a
downconverter path and an upconverter path.
3.2.4 POWER SUPPLY
The power supply assembly consists of a Power Entry Module and switching power supply. The power
supply accepts a
100 to 240 VAC, 3A, 50/60 Hz input and outputs +15 VDC for use by the rest of the amplifier.
Power is distributed to the active modules through the Control/Distribution board.
3.2.5 CONTROL/DISTRIBUTION MODULE
The control/distribution module distributes power to the other modules, receives and processes status and
fault information, and provides forward channel frequency control. Power distribution consists of current
monitoring of both the forward and reverse channel PA’s, linearly regulating the +15 VDC down to +12 and
+5 VDC for various modules. Status functions include monitoring RSSI voltages from the channelizers,
monitoring forward output power, and driving the appropriate front panel LED’s. Channel frequency
selection information is received via RS-232 from the front panel and is processed by an on board
microcontroller. This information is also stored in ROM (Read Only Memory), so that frequency settings
are not lost if AC input power is lost. The microcontroller sends the frequency information via a three wire
interface to the appropriate channelizer. Various faults on the channelizers, broadband, and the
control/distribution module itself are monitored and displayed on the front panel. A rear panel contact
closure (closed when unit is operating normally) is provided for external monitoring.
3.2.6 POWER AMPLIFIER MODULES
The power amplifier module provides the final gain and power stages for the amplifier. A 5 Watt Peak Class
A linear amplifier is used for the forward channel. This 5 Watt unit has approximately 27 dB gain. A 1.6
Watt Peak Class A linear amplifier is used for the reverse channel. The 1.6 Watt unit has approximately
30 dB gain. The DC current draw of each power amplifer is monitored by a window comparator.