Avionics & airborne LRUs: Communication System
Radio Selector Unit SEERSU74A/1/1
Instructor-selector communication control for airborne systems
The SEERSU74A/1/1 forms part of an airborne communications control system and is used as an instructor’s selector unit, providing amplification of microphone and receiver signals for use with a 300-ohm microphone. It supports NORMAL and standby operating modes, includes MUTE and CALL controls, and uses duplicated amplifier paths with independent 28V DC sources plus a front-panel test switch for redundancy checks.
KEY DETAILS
Used as an instructor’s selector unit in airborne communication systems
Designed for use with a 300Ω microphone
NORMAL/SBY switch changes available transmit and receive paths
Includes single overall gain control, MUTE button, CALL button and standby indicator lamp
Duplicated amplifier and power supply architecture with test-switch verification
