A-6
ATLAS 4500 Multimode Station Technical Manual
135-175 MHz Receiver Module
Appendix A - VHF Circuit Descriptions
IC30 and IC48 are linear regulators regulating the +5 V supply down to +3.3 V DC
for the synthesizers.
IC33 is a multi-circuit buck DC-DC converters and low drop out regulators that
p3.3 V, +2.5 V, +1.8 V and +1.2 V for various circuit sections in the digital
portion of the exciter including the FPGA, memory and DDS, etc.
A.2 135-175 MHz Receiver Module
This section contains information on the following Receiver Module components:
• Frequency Synthesizer
• RX VCO Board
• Reference Clock
• Front End
• 55 MHz IF Section
• Receiver DC Supplies
A.2.1 General Description
The receiver module converts a low level RF signal from an antenna input to a 55
MHz intermediate frequency (IF) output for processing with the DSP RX Logic
board.
The module has two SMB connectors for RF I/P and 55 MHz IF O/P.
The receiver module consists of two circuit boards. A Voltage Controlled
Oscillator (VCO) board and an RX board with associated frequency synthesizers,
down converter, TCXO, filtering circuits and internal power supply circuits.
Receiver input frequency programming is achieved by using serial data connections
to an external controller.
