1、A-A-59003/8 31 May 1995 SUPERSEDING MIL-A-21577/8 27 February 1967 COMMERCIAL ITEM DESCRIPTION AMPLIFIER-CONTROL GROUP AN/SIA-120 The General Services Administration has authorized the use of this commercial item description as a replacement for MIL-A-21577/8A which is canceled. 1. Scope. This comme
2、rcial item description covers the detailed requirements for an audio amplifier-control group type AN/SIA-120. 2. Sallient characteristics. 2.1 General. Amplifier-control group AN/SIA-120 shall be in accordance with the applicable paragraphs of A-A-59003 and as specified herein. Whenever a requiremen
3、t of A-A-59003 conflicts with a requirement of this specification, the requirement of this specification shall govern. 2.2 Equipment. The equipment complement shall consist of two power amplifiers and all relays, meters, switches, terminals, and wiring required to provide control switching and ampli
4、fication of voice signals for use in announcing system, circuit 2MC, mounted in a common bulkhead enclosure. 2.2.1 Preamplifier. Preamplifiers shall be included as a part of each power amplifier. 2.3 Construction. Power amplifiers shall be modular construction with quick disconnect features to permi
5、t easy removal of the amplifiers for servicing. 2.4 Relays. Relays with the exception of power type contactors may be hermetically sealed. 2.5 Output power. The output power of the individual power amplifier units shall be 20 watts minimum rating. 2.6 Input facilities. Input facilities shall be prov
6、ided to accommodate five microphones (type IC/MPM or type IC/MFM). A test input receptacle assembly to permit connection of a microphone shall be provided on the AN/SIA-120 control rack front panel. In addition, wiring shall be provided to the terminal block from the amplifier terminals to provide i
7、nsertion of alarm signals from an external source. 2.6.1 Microphone circuits. Each of the five microphone circuits shall be independently connected by means of relays to the amplifier input so that only the microphone in use is connected to the input of the amplifier. AMSC N/A FSC 6320 DISTRIBUTION
8、STATEMENT A. Approved for public release; distribution is unlimited. Licensed by Information Handling ServicesA-A-59003/8 m 9999974 0368382 b30 A-A-59003/8 2.6.2 Amplifier inputs. The two amplifier inputs shall be connected in parallel and connected to the output of the microphone relays through a s
9、uitable resistance network to provide the required 150 ohms input impedance. 2.7 Loudspeaker groups. Five loudspeaker output groups shall be provided. Three position switches shall permit connecting any or all of the output groups to the output of either of the amplifier assemblies. Parallel connect
10、ion of the outputs of the two amplifiers will not be required. 2.7.1 Cutout relay. A local loudspeaker cutout relay shall be included for each microphone circuit to disconnect local loudspeakers when the microphone is in use. 2.8 Circuit transfer switches. Circuit transfer switching shall be as 2.9
11、Output metering and switching. specified in 2.6 and 2.7. An output volume indicating meter and its associated output selector switch shall be provided and shall make it possible to measure the output of either amplifier selected for test. The maximum weight and size of the AN/SIA- 120 amplifier-cont
12、rol group shall be: weight, 45.36 kg; height, 508 mm; width, 254 mm; and depth, 254 mm. 3. Quality assurance. Sampling, examination, and tests shall be as 4. Packaging. Packaging shall be as specified in accordance with A-A- 2.10 Maximum weight and size - specified in accordance with A-A-59003. 5900
13、3. 5. Notes. 5.1 Intended use. Amplifier-control group AN/SlA-120 is intended for use in shipboard announcing system, circuit 2MC. specification. 5.2 Notes. The notes specified in A-A-59003 are applicable to this Preparing activity: Navy - SH (Project 63 2 O -NO54 1 2 Licensed by Information Handling Services
