MIL-DTL-21393B
(Copies of these documents are available from https://www.ncsli.org or to National Conference of
Standards Laboratories (NCSL), 2995 Wilderness Place, Suite 107, Boulder, CO 80301-5404.)
2.4 Order of precedence. 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, however, 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 the requirements
of this specification and the specification sheet, the latter shall govern.
3.2 First article test. When specified (see 6.2), a sample shall be subjected to first article inspection in
accordance with 4.3.
3.2.1 Microphone only. First article test shall apply only to the microphones.
3.3 Materials. ASTM D5927 thermoplastic polyester and similar materials shall be used, which shall
enable the microphone to meet the performance requirements of this specification.
3.4..General design requirements (see 4.6.3.1).
3.4.1 Marking. Each microphone unit shall be permanently and legibly marked as shown on figure 1.
The manufacturer's trademark may be added if desired.
3.4.2 Reliability (see 4.7). For operational stability, the microphones shall operate with optimum
performance for 500 hours, continuously or intermittently.
3.4.3 Insulating and impregnating compounds. All such compounds including varnishes, waxes and
the like, shall be suitable in every respect for each particular application. Under all service conditions
including test conditions outlined in section 4 of this specification, the compound shall allow the insulation,
on which it is applied, and the microphone assembly to meet all performance and environmental
requirements of this specification.
3.5 Detail requirements. The design and assembly of the microphone shall be such that the
microphone is inherently stable, as to mechanical and electrical characteristics. The contractor, subject to
the requirements of this specification, shall accomplish the detailed mechanical and electrical design of
the microphones. The requirements are detailed herein only to the extent considered necessary to obtain
the desired mechanical and electrical characteristics and performance, and permanence of the same.
3.5.1 Microphones, dynamic M21393/1-01 and M21393/2-01. The microphones shall meet the
following requirements.
3.5.1.1 Function. The microphones shall convert normal speech input to electrical signals suitable for
connection into the speech amplifiers and/or modulators of radio or audio equipment. The microphones
shall discriminate in favor of the speech signals and against ambient noise.
3
For Parts Inquires call Parts Hangar, Inc (727) 493-0744
© Copyright 2015 Integrated Publishing, Inc.
A Service Disabled Veteran Owned Small Business