Figure 2-7.—AN/SAT 2 infrared transmitting set.

Figure 2-7.—AN/SAT 2 infrared transmitting set. The IR transmitting set consists of two IR transmitters (beacons), a transmitter control panel, and two telegraph keys. The beacons may be operated separately or simultaneously by either manual key. Selection of the mode of operation is controlled by the transmitter control panel. The IR transmitter consists of a formed brass housing and a dome-shaped homogeneous tempered glass filter, which encloses a 300-watt, 110-volt, T20 clear bulb incandescent lamp and reflector. The transmitter control consists of a watertight brass housing with a removable front cover, and contains a switch, four fuses, two indicator lights, two terminal boards, and associated wiring. The front panel has a gasket to ensure a watertight fit, and is fastened to the housing by means of eight machine screws. Two locating pins ensure proper alignment of the door and housing. (This control panel is also utilized by the yardarm blinkers; however, this blinker is powered by a separate ship's power supply to ensure the circuit is inoperable during darken ship.) The telegraph key consists of a watertight brass box containing a signaling key, a monitor indicator light, a terminal board, and a capacitor. The watertight housing consists of a formed and welded steel box with a formed steel cover and key guard. The cover is attached to the housing by means of six machine screws. A locating pin ensures proper alignment. The base of the housing has three mounting lugs. The hinged key guard on the cover protects the key from damage when it is not in use. A hold-down lever permits steady operation of the beacons when placed in the down position. Due to the constant exposure to the elements, strict compliance with planned maintenance system (PMS) requirements is essential for this equipment. Normally, maintenance is the responsibility of the Electrician's Mates. Cleanliness and upkeep of the light exteriors are tasks for Signalmen. This upkeep can be hazardous. Before going aloft, check Man Aloft Procedures covered later in this chapter. The most widely used IR transmitting equipment is the standard 12-inch searchlight fitted with a type-H hood containing the special filter lens (fig. 2-8). The lens resembles a sheet of red glass. The light is operated in the same procedure for regular directional communication, but train must be more accurate. 2-7