DLA MIL-PRF-26542 F-2012 MICROPHONE AND MICROPHONE ASSEMBLIES DYNAMIC GENERAL SPECIFICATION FOR.pdf

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1、AMSC N/A FSC 5965 MIL-PRF-26542F 12 September 2012 SUPERSEDING MIL-PRF-26542E 30 May 1997 PERFORMANCE SPECIFICATION MICROPHONE, AND MICROPHONE ASSEMBLIES, DYNAMIC GENERAL SPECIFICATION FOR This specification is approved for use by all Departments and Agencies of the Department of Defense 1. SCOPE 1.

2、1 Scope. This specification covers the general requirements for moving coil, noise-canceling dynamic microphones. The products described herein are used in oxygen and gas-masks, and headset-microphones (boom-mounted and protective-shield mounted). These parts provide communications within moderate t

3、o high noise environments, at ground level and altitude, as specified, and meet established United States Air Force sensitivity standards (see 6.1). 1.2 Classification. 1.2.1 Type. Microphones (see 3.1) covered by this specification should all be of the following types: a. Type I Boom mounted (inclu

4、ding boom, cable and connector). b. Type II Mask mounted (including bracket and cable assembly). 2. APPLICABLE DOCUMENTS 2.1 General. The documents listed in this section are specified in sections 3, 4, or 5 of this specification. This section does not include documents cited in other sections of th

5、is specification or recommended for additional information or as examples. While every effort has been made to ensure the completeness of this list, document users are cautioned that they must meet all specified requirements documents cited in sections 3, 4, or 5 of this specification, whether or no

6、t they are listed. 2.2 Government documents. 2.2.1 Specifications, standards, and handbooks. The following specifications, standards, and handbooks form a part of this document to the extent specified herein. Unless otherwise specified, the issues of these documents are those cited in the solicitati

7、on or contract. DEPARTMENT OF DEFENSE SPECIFICATION MIL-DTL-22442 - Cable Assemblies, Aircraft Audio, General Specification for. (See ASSIST database for list of specification sheets) Since Navy-EC is the Navy custodian for this document, all Navy review activities should forward their comments dire

8、ctly to DLA Land and Maritime. Beneficial comments, recommendations, additions, deletions, clarifications, etc., and any data that may improve this document should be sent to: DLA-CC, DLA Land and Maritime, ATTN: VAI, P.O. Box 3990, Columbus, Ohio 43218-3990 or emailed to sounddscc.dla.mil. Since co

9、ntact information can change, you may want to verify the currency of this address information using the ASSIST Online database at https:/assist.dla.mil. INCH-POUND Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-PRF-26542F 2 DEPARTMENT OF DEFENSE

10、 STANDARDS MIL-STD-202 - Test Methods for Electronic and Electrical Component Parts. MIL-STD-810 - Environmental Test Methods and Engineering Guidelines. MIL-STD-1285 - Marking of Electrical and Electronic Parts. (Copies of these documents are available online at https:/assist.dla.mil/quicksearch/ o

11、r from the Standardization Document Order Desk, 700 Robbins Avenue, Building 4D, Philadelphia, PA 19111-5094.) 2.2.2 Other Government documents, drawings, and publications. The following other Government documents, drawings, and publications form a part of this document to the extent specified herei

12、n. Unless otherwise specified, the issues are those cited in the solicitation. DRAWING NAVY (CAGE 80063) SK-N-864 - Simulated Gun Blast Producing Equipment (Copies of this document required by contractors in connection with specific acquisition functions may be obtained from the procuring activity a

13、t DSCC.cddwgsdla.mil, or as directed by the contracting officer.) 2.3 Non-Government publications. The following documents form a part of this document to the extent specified herein. Unless otherwise specified, the issues of these documents are those cited in the solicitation or contract. AMERICAN

14、NATIONAL STANDARDS INSTITUTE (ANSI) ANSI S1.15 Measurement Microphones Part 2: Primary Method for Pressure Calibration of Laboratory Standard Microphones by the Reciprocity Technique. (Copies of these documents are available online at http:/www.ansi.org or from the American National Standard Institu

15、te, 25 West 43 Street, 4thFloor, New York, NY 10036.) MAGNETIC MATERIALS PRODUCERS ASSOCIATION (MMPA) MMPA 0100-00 - Standard Specifications for Permanent Magnet Materials. (Application for copies should be addressed to Magnetic Materials Producers Association, 8 South Michigan Avenue, Suite 1000, C

16、hicago, IL 60603.) (Industry association specifications and standards are generally available for reference from libraries. They are also distributed among technical groups and using Federal agencies.) Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-

17、MIL-PRF-26542F 3 2.4 Order of precedence. Unless otherwise noted herein or in the contract, in the event of a conflict between the text of this document and the references cited herein (except for related specification sheets), the text of this document takes precedence. Nothing in this document, ho

18、wever, supersedes applicable laws and regulations unless a specific exemption has been obtained. 3. REQUIREMENTS 3.1 Specification sheets. The individual item requirements shall be as specified herein and in accordance with the applicable specification sheet. In the event of any conflict between req

19、uirements of this specification and the specification sheet, the latter shall govern. 3.2 Qualification. Microphones furnished under this specification shall be products that are authorized by the qualifying activity for listing on the applicable qualified products list before contract award (see 4.

20、5 and 6.3). 3.3 Materials. All materials shall enable the parts to meet the performance requirements of this specification. Materials which have measurable changes in property due to aging shall not be used, such as ferrite magnets. Acceptance or approval of any constituent material shall not be con

21、strued as a guaranty of the acceptance of the finished product. 3.3.1 Recycled, recovered, or environmentally preferable materials. Recycled, recovered, or environmentally preferable materials should be used to the maximum extent possible provided that the material meets or exceeds the specified req

22、uirements (see 3.1), and promotes economically advantageous life cycle costs. 3.3.1.1 Unacceptable materials. Natural rubber or natural rubber cement shall not be used in the microphone element. Rubber substitutes and plastic materials shall not be used as wedges and fillers. 3.3.2 Diaphragm materia

23、l. The diaphragm material shall be metal or Mylar, or material having equivalent or superior environmental and durability requirements in accordance with this specification. 3.3.3 Magnetic material. The magnetic material shall be in accordance with MMPA 0100-00. 3.3.4 Pure tin (see 6.5). The use of

24、pure tin, as an underplate or final finish, is prohibited both internally and externally. Tin content of microphone and microphone assembly components and solder shall not exceed 97 percent, by mass. Tin shall be alloyed with a minimum of 3 percent lead, by mass. 3.4 Interface. 3.4.1 Cement. All cem

25、ents shall be used in accordance with the manufacturers or suppliers product specification sheet. Cements shall not corrode or otherwise degrade the properties of materials to which they are applied, nor to materials to which they are adjacent. 3.4.2 Color. The exterior of the microphone element sha

26、ll be lusterless black, providing low contrast with operational clothing and gear. 3.4.3 Components. Components which are supplied with the complete assembly shall be as specified (see 3.1). 3.4.4 Cleanliness of air gap. There shall be no foreign material present in the air gap of the microphone ele

27、ment when viewed through a microscope having a magnification of at least fifteen. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-PRF-26542F 4 3.4.5 Cable assemblies. Unless otherwise specified (see 3.1), cord assemblies shall meet either of the

28、2 two) following requirements, to ensure a quality interfacing product. a. The use of QPL cord assemblies referenced in MIL-DTL-22442. b. Verification and approval by the qualifying activity of meeting the technical requirement of MIL-DTL-22442. NOTE: Both of the above methods require qualification

29、of the entire specification product to the applicable qualification requirements. 3.4.6 Weight. Weight shall be as specified (see 3.1). 3.5 Performance. Parameter applicability shall be as specified (see 3.1). Performance variations allowable, following subjection to environmental exposures, shall u

30、tilize the initial group 1 measurements as a reference. Performance variations are not cumulative with multiple environmental exposures. See 3.5.30. 3.5.1 Sensitivity at ground level (see 4.5.2.2). The sensitivity shall be as specified (see 3.1). 3.5.2 Sensitivity at altitude (see 4.5.2.3). When app

31、licable, the sensitivity at the simulated altitude shall be as specified (see 3.1). 3.5.3 Frequency response at ground level (see 4.5.2.4). The frequency response of the microphone shall be within the frequency response limits specified (see 3.1). 3.5.4 Frequency response at altitude (see 4.5.2.5).

32、When applicable, the frequency response at the simulated altitude shall be as specified (see 3.1). 3.5.5 Impedance (see 4.5.3). The impedance at any frequency over the specified frequency response range (see 3.1) shall not deviate from the impedance at 1,000 Hz by more than 10 percent, unless otherw

33、ise specified (see 3.1). 3.5.5.1 Impedance limits (see 4.5.3). The impedance at 1,000 Hz and at 20 degrees C (68 degrees F) shall be as specified (see 3.1). 3.5.6 Total harmonic distortion (see 4.5.4). Unless otherwise specified (see 3.1), the total harmonic distortion in the output of the microphon

34、e within the specified frequency response range (see 3.1) shall not exceed 6 percent with an input sound pressure of 114 dB relative to 20 micropascals (Pa). 3.5.7 Signal-to-acoustic noise (see 4.5.5). For the purpose of qualification, the noise cancellation characteristics shall be in accordance wi

35、th 3.5.7.1. For the purpose of quality assurance, the noise immunity characteristics shall be in accordance with 3.5.7.1 or 3.5.7.2 at the manufacturers option. The microphone shall discriminate in favor of speech signals and against acoustic noise. 3.5.7.1 Noise cancellation characteristics (see 4.

36、5.5.1). The noise cancellation characteristic of the microphone shall be such that the “average difference curve” and the peaks of the ”difference curve A” and “difference curve B”, derived from the frequency response characteristics of the microphone to a “close” and “distant” sound source as speci

37、fied herein, shall fall within an envelope having a slope of not less than 6 dB per octave falling between 200 Hz and 4,000 Hz. The “difference curve A” and the “difference curve B” may go through the envelope on the lower side. But, they shall not go through the envelope on the top side. The center

38、line of the envelope shall intersect the zero axis, between 5,000 Hz and 8,000 Hz. 3.5.7.2 Noise-immunity characteristic. Under standard conditions, the signal-to-noise ratio shall be at least 15 dB in favor of the signal, when measured in accordance with 4.5.5.2. Provided by IHSNot for ResaleNo rep

39、roduction or networking permitted without license from IHS-,-,-MIL-PRF-26542F 5 3.5.8 Effect of external magnetic field (see 4.5.6). The sensitivity of the microphone to an external 400 Hz magnetic field shall not be more than 25 percent of that of a coil consisting of 123 turns of No. 34 enameled w

40、ire closely wound in a single-layer solenoid upon a nonconductive, nonmagnetic mandrel 0.500 inch in diameter, placed in the same magnetic field. 3.5.9 Stray magnetic field (see 4.5.7). Unless otherwise specified (see 3.1), the stray magnetic field of the microphone shall cause no more than a 5 degr

41、ee deflection of a magnetic compass at a distance of 12 inches. 3.5.10 Linearity (see 4.5.8). The output of the microphone shall be a linear function of the sound pressure input to the microphone in the range of inputs from 74 dB to 114 dB inclusive, relative to 20 Pa at any frequency within the spe

42、cified frequency response range (see 3.1). A 20 dB increment in acoustic input shall yield a 20 dB 1 dB increment in the voltage output. 3.5.11 Talk-out (see 4.5.9). There shall be no subjective difference in the output of the microphone by talking into the front and the back sound ports with equal

43、loudness and with lips touching the moisture-barrier guard. 3.5.12 Dielectric withstanding voltage (see 4.5.10). The product shall operate safely at its rated voltage, and withstand momentary over-potentials due to switching, surges, and other similar phenomena. It shall be capable of withstanding a

44、 voltage higher than its rated voltage, for a prolonged period of time, between mutually insulated portions of the product and between insulated portions and ground. This shall not result in either arcing or breakdown of insulation. Following such exposure, the impedance shall change not more than 1

45、 ohm or 5 percent from the initial measured value, whichever is greater. 3.5.13 Interchangeability (see 4.5.11). Like units, assemblies, subassemblies, and replaceable parts shall be electrically and mechanically interchangeable. Design tolerances shall permit parts, subassemblies and assemblies to

46、be used without regard to the source of supply or manufacturer. 3.5.14 Thermal shock (see 4.5.12). The product shall resist degradation in performance due to exposure to extremes of high and low temperatures, and to the shock of alternate exposures to these extremes, such as would be experienced whe

47、n parts are transferred to and from heated shelters in arctic areas. Following such exposure, the product shall exhibit the following performance: Visual examination: Sensitivity and frequency response: Impedance: No evidence of physical damage which would cause a malfunction. No more than 3 dB vari

48、ation at any frequency, when referenced to the initial response. No more than 1 ohm or 5 percent variation from initial reading, whichever is greater. 3.5.15 Humidity (see 4.5.13). The product shall resist degradation in performance due to exposure to extremes of a warm, humid atmosphere, resisting

49、such defects as corrosion, biological growth, material property changes due to moisture penetration, and effects of condensation. Following such exposure, the product shall exhibit the following performance: Visual examination: Sensitivity and frequency response: Impedance: No evidence of physical damage which would cause a malfunction. No more than 3 dB variation at any frequency, when referenced to the initial response. No more than 1 ohm or 5 percen