A-A-52421 Accessory Kit; Warning Device, Demountable, For Emergency VehiclesThis CID covers a 14 volt and 28 volt demountable warning device consisting of a support bar and brackets for rain gutter mounting and gutterless mounting of two rotating warning lights, speaker, electrical harness, electronic siren and public address (P/A) system with microphone for use on security and other emergency vehicles having 12 or 24 volt electrical systems. The accessory kit and its associated hardware is referred to herein as "warning kit".

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A-A-52421A(AT)

 2 2.1.1 Painted finish. When specified (see 6.2), a painted finish shall be applied in accordance with detail requirements furnished by the acquisitioning activity.

2.1.2 Dissimilar metals. Except where necessary to complete an electrical circuit, contact between dissimilar metals which would encourage galvanic action shall be avoided. Separation of dissimilar metals shall be accomplished by providing insulation between mating surfaces.

2.2 Design and construction. The warning kit shall come in one of the types and classes specified depending on the voltage and dome color required (see 1.1 and 5.2).

2.2.1 Rotating warning lights. The rotating warning lights shall meet the requirements of A-A-52418. The rotating warning lights shall have a plate completely enclosing the bottom of the housing for mounting onto the bar.

2.2.2 Speaker. A round speaker, having an impedance of between 13 and 16 ohms, shall be supplied with a driver rating of 75 watts (nominal). The speaker shall be weatherproof and corrosion resistant with a mounting plate provided for attachment to the bar.

2.2.3 Mounting bar. The mounting bar with warning lights and speaker shall be in accordance with figure 1. The mounting bar must be mountable on gutterless vehicles or vehicles with conventional rain gutters and it shall be adjustable to accommodate gutters spaced (or roof widths) from 54 inches to 66 inches. All wiring for the warning lights and speaker shall be inside the bar or component with adequate allowances for the full range of bar adjustment. The connector shall extend 1 inch to 4 inches from the end of the mounting bar on the driver’s side, and shall be on the rear of the mounting bar. Attaching hardware shall be weather and corrosion resistant, and wire holes in the bar shall be fitted with grommets. Mounting clamps must be tamperproof as far as practicable (employ some method of attachment that discourages vandalism).

2.2.4 Electronic siren and public address system. The siren shall be in accordance with figure 2. Separate on-off switches shall be provided for the siren and warning lights. With the siren switch “ON” either the Alert (yelp), Wail (coaster), HI-LO or P/A (public address system) must be selectable. The microphone shall be of the noise canceling type (magnetic) to limit feedback. The microphone cord shall be retractable and eight feet in length. All control knobs shall be functionally marked. Instructions shall be clearly and permanently displayed on the control unit. All knobs and functional markings on the unit shall be illuminated for night viewing with adequate contrast and brightness. Warning light and siren circuits shall be fused separately. In the public address mode a zero to full attenuation volume control shall be provided. An amplifier connector shall be included to mate with the harness connector in figure 3 (see 2.2.5).

2.2.4.1 Siren tone range. The ratio of the highest fundamental frequency to the lowest shall be 3 to 1. The highest fundamental frequency shall not exceed 1500 Hz.

2.2.4.2 Siren tone modulation.