AN/GRA-39

The AN/GRA-39 is used in conjunction with a radio receiver-transmitter or a local battery switchboard to expand the interfacing capability of the radio or switchboard. When connected with a radio, the AN/GRA-39 enables the operator to transmit and receive voice frequency communications through the radio for a distance of up to two miles (3.3 kilometers) from the radio. When connected with a switchboard, the AN/GRA-39 is used 10 accomplish net radio interface (NRI), by which voice communication is established between a field telephone (switchboard subscriber) and a radio. In either application, communication can be initiated by the remote control unit operator or by the local control unit operator. Transmissions initiating at the local control unit do not involve the remote control unit. However, transmissions initiating at the remote unit require the presence of an appropriately set local unit in the system.

When a handset is connected to both the local control unit and the remote control unit, two-way communication is possible between the two units independent of any radio or switchboard in the system.

The local and remote control units are battery powered. The two units have identical battery requirements. Each control unit has a waterproof case, and each has two D-rings for attachment of a sling which allows the unit to be carried or hung on an appropriate object. All operating controls on each unit are located in the front panel.