AN/ARC-153 HF Airborne Communications System
The Radio Set AN/ARC-153( ) (HF radio) is a two-channel, SSB HF radio that operates with an antenna coupler and a power amplifier. The HF radio set is capable of receiving and transmitting both voice and Link 11 data signals in USB, LSB, DSB, and AME. The AME is provided in the USB voice channel only.
The functional description of the set's receiver-exciter is divided into three basic operating functions: control, receive, and transmit.
- Control: Parallel function, mode, and frequency information from the HF Switching Logic Unit (SLU) is applied to the parallel control. The parallel control corrects parallel information from the differential receivers to low-level logic and BCD information. Control logic (mode and control information) is applied throughout the receiver-exciter. Part of the control logic is applied directly, while the remainder is processed by the logic control section before being applied.
Receive: The incoming (receive) RF signal from the antenna is applied through a Transmit-Receive (TR) switching circuit and a bandpass filter to the 1/2-octave bandswitch network.
Transmit: A 600-or 150 ohm audio input is transformed and applied to a data audio amplifier or a voice input amplifier. The resultant audio signal is applied to a balanced modulator where a 450-kHz carrier is injected. This double-sideband, 450-kHz signal is applied to either a USB or LSB mechanical filter which removes the unwanted sideband. The resultant sideband signals, if DSB is chosen, are combined in the multiplex combiner and are applied to the 450-kHz IF amplifiers. If AME is chosen, the USB signal is reduced by 6 dB at the multiplex combiner and is combined with a 6-dB reduced carrier. Also, to keep the peak envelope power constant, the multiplex combiner reduces the channel gain by 6 dB if DSB is chosen.
The set's power amplifier receives RF signals from the transmitter-receiver at a maximum 100-mW peak envelope power level in the 2.0000- to 29.9999-MHz frequency spectrum. The RF input from the transmitter-receiver enters the RF amplifier through an input amplifier. This input amplifier provides gain compensation, signal limiting, and amplification. The output from the input amplifier is applied to the driver-amplifier.
The driver-amplifier stage provides the required drive the impedance transformation to the input of the power amplifier stage. The driver-plate network is band switched to l of 12 bands in the 2. 0000- to 29.9999-MHz frequency spectrum and servo-tuned over that band by a variable inductor. The power amplifier stage raises the RF signal to the required 1000-W output with a minimum of distortion, and applies it to the pi-type power amplifier output network. The capacitive elements of the pi network are band switched to 1 of 12 bands; then tuning within the band is accomplished with a servo-driven variable inductor. The impedance of the power amplifier output network matches a 50-ohm unbalanced coaxial line. The output network can tune into mismatched conditions that do not exceed 1.3:1 Voltage Standing Wave Ratio (VSWR). The power amplifier is a 1-kW peak envelope power linear power amplifier. It operates in the 2.000-to 29.9999-MHz frequency spectrum with emission in AME, Single-Sideband (SSB), and DSB modes. The internal power supply to the necessary operating voltages. The power amplifier is housed in a pressurized case that contains an air-to-air heat exchanger. An internal blower circulates air inside the sealed case through the internal passages of the heat exchanger. Internal monitors provide a go/no-go test for the power amplifier.
The control circuits contain the interface for the external control system, external receiver-transmitter, power supply, power amplifier gain control circuits, servo tuning, and band switching circuits, monitoring circuits, protective devices, and BITE circuits.
The set is being manufactured by Rockwell-Collins for the Navy's ERA-3B.
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