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 TM 55-1905-220-14-9
4-47.3. LOUD HAILER- MAINTENANCE INSTRUCTIONS
a. General.
(1)
Functional Description.
(a) This loud hailer is used to amplify the human voice just as does any public address system, for
the purpose of talking to personnel over distances too far for the unaided voice to be under- stood, or to permit
the talker's voice to be heard in noisy locations. For portable operation no other equipment or power source is
required, as the loud hailer contains its own dry cell batteries. Where limited portability is practicable, the
electrical power may be supplied to the loud hailer from a 12 volt storage battery through the accessory power
cable furnished with the equipment.
(b) This equipment is suitable for use in exposed locations. It will withstand vibration and salt spray
and is built to perform under extremes of temperatures and high humidity. The driver unit, microphone,
amplifier enclosure, and battery enclosure are watertight.
(c) This loud hailer consists essentially of a horn loud- speaker, a microphone, a transistor amplifier,
eight (size D) batteries, and a pistol-grip handle with trigger switch. These elements are combined in one unit
assembly. To use the unit, grasp the pistol grip handle with one hand and raise the unit so that the rubber
microphone mouthpiece is almost touching the mouth, and direct the horn in the direction it is desired to
communicate. The hand grasping the handle operates the trigger switch which activates the loud hailer, and the
talker speaks into the microphone in a strong command voice. As soon as the message is finished the trigger
switch is released. The handle is so designed and located that the whole assembly balances perfectly on the
grasping hand, thus requiring a minimum of effort to tilt the unit up or down.
(d) The assembly is designed to provide ease of access for servicing or repair. The microphone unit
is mounted within a grille housing on the rear, which is easily removeable. The amplifier is contained in a
cylindrical housing, which is also easily removable from the rest of the assembly, the amplifier cartridge being
held within by three machines screws.
(e) With the rear housing removed, the loudspeaker driver unit mechanism is also accessible. The
horn assembly is secured to the driver mechanism, and contains within it a molded plastic lug. The lung forms
a part of the horn assembly, but it is hollow and fitted with a cover. The interior of this lung is designed as a
battery cartridge, so that when the cover is removed the required dry cell batteries can be inserted in the
spaces provided. As the interior of the lung and its cover contain contact springs, it is only necessary to screw
the cover on again to make the necessary electrical connections to the batteries.
4-1192
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