The MSR Transmitter is a completely redundant, digitally controlled, high power, F-Band radar transmitter. The function of the transmitter is to amplify waveforms received from an external source and forward them to the Antenna Group for steering and transmission into space.
Functionally, the Transmitter Group is a three stage device of the signal generation/driver/power amplifier configuration.
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First Stage:
Low Level Transmitter (LLT) combines RF inputs from an external source (derived from crystal controlled oscillator circuits) with its own local oscillators to generate the final F-Band transmit frequency. Also provides the Receiver Group with its first and second Local Oscillator signals.
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Second Stage:
The Driver takes the low level RF signal (approx 2.25 watts) from the LLT, amplifies it to that level required to drive both Final Power Amplifiers (FPA's). Driver output is via a single medium power TWT (Varian 643) and several variable attenuators, waveguide switches and phase shifters. The attenuators are used to control the driver output signal levels, the switches perform redundancy switching during a fault condition and the phase shifters are used to optimize the combined output from the two FPA's when operating with both klystrons in parallel.
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Third Stage:
The FPA's, in turn, amplify this signal and feed it to the Antenna Group through a ferrite switching network that routes the high power to one of the four faces. The Transmitter Control Group provides automatic or manual control, test, and status monitoring facilities for the drive stage, final stage, and output switching network of the Transmitter Group. Signal characteristics such as waveform, pulse configuration, and modulation of the transmit signal are determined by data processor instructions during normal system operation. Built in Test Equipment permits independent operation of any/all equipment for maintenance purposes.
The transmitter equipment occupies an area of approximately 18,200 square feet. This includes two high voltage power supply rooms, a klystron room, a transmitter control room, two power supply control rooms, a microwave balcony, an oil pumping room, and the main ancillary room which maintains the SF6, and high pure water monitor and pumping equipment.This does not include the anecoic chambers where the transmitter feedhorn is located.
Power:
Three 3100 KW diesel generators are dedicated to the Transmitter Group, of which one is kept on standby as a spare.
Oil:
The oil cooling system consists of five modules 10' x 5' x 8' high which contain equipment for continuously purifying and circulating oil at a rate of 120 GPM, storing 24,000 gallons of clean and contaminated oil, and a reclaimer for repurifying contaminated oil at a rate of 10 GPM.
High Purity Water Cooling Group:
The high purity water cooling system consists of 12 modules 10' x 5' x 7' high which contain equipment for circulating 2790 GPM of deionized water to nine distribution modules 10' x 2.5' x 8' high, which in turn, supply 64 separate cooling loops with deionized water.
Gas Pressurization Group - SF6:
The SF6 gas pressurization system consists of two modules 10' x 5' x 7' high which contain equipment for cooling, circulating and drying sulfur hexafluoride gas used throughout all high power waveguide runs of the Transmitter group.