Aviation Electronics Technician 1 - Historic Naval Ships Association

Table 1-3.-UHF-1 and UHF-2 Operating Modesguard receiver is a separate module and is a completeand independent fixed-tuned, crystal-controlledreceiver that operates on the guard frequencies. Thereceiver sections receive command signals from thecontrol box, placing it in the proper condition for themode selected. All receiver outputs derived from guard,FM, FSK, wide-band, and voice modes are routedthrough the audio interface, and then switched throughthe COMM switching matrix to the external equipment.UHF-2 ReceiveThe RF signal received at the UHF tailcap or UHFlower antenna is coupled into the UHF-2 RT through theantenna switching relay, and the UHF filter. From thispoint on, the operation is the same as in the UHF-1 radioset.Modes of OperationTable 1-3 shows the modes of operation for the tworadio sets.HF COMMUNICATIONSLearning Objective: Recognize componentsand operating principles of the HF radiosystem.The AN/ARC-161 HF radio system providestwo-way communications between the aircraft and anysimilarly equipped platform. It provides transmission,reception, and processing of intelligence and tacticaldata. The cipher voice communication is provided bythe TSEC/KY-75 high-frequency security unit.1-16