MIL-DTL-25879G
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 the documents are those cited in the solicitation or contract (see
6.2).
NATIONAL CONFERENCE OF STANDARDS LABORATORIES (NCSL)
NCSL-Z540.3
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Calibration Laboratories and Measuring and Test Equipment.
(Copies can be obtained online at https://www.ncsli.org or from National Conference of Standards Laboratories
(NCSL), 2995 Wilderness Place, Suite 107, Boulder, CO 80301-5404)
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, 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 First article approval. Coaxial switches furnished under this specification shall be a product which meets
requirements for first article approval (see 4.4 and 6.3). The switch, SA-521A/A, and mounting, MT-1995/A (see MIL-
DTL-32054), shall be first article approved together and at the same time (see figure 1).
3.1.1 Classification. The SA-521A/A switch shall be designed for 70,000 ft. altitude and continuous sea level
operation over the temperature range of -54 to +71C (+95 intermittent operation), with exceptions as specified
herein.
3.1.2 Materials. Materials shall be used that will enable the switches to meet the requirements of this specification.
Acceptance or approval of any constituent material shall not be construed as a guaranty of the acceptance of the
finished product (see 4.2).
3.1.2.1 Dissimilar metals. Unless suitably protected against electrolytic corrosion, dissimilar metals shall not be
used in intimate contact with each other. Dissimilar metals are defined as metal specimens that are in contact or
otherwise electrically connected to each other in a conductive solution and that generate an electric current.
3.1.2.2 Fungus. Materials used in the construction of switches shall be fungus inert. Fungus inert material is
defined as a material which, in all modified states and grades, is not a nutrient to fungi.
3.1.2.3 Finish. If the body of a switch is painted, it shall be painted with a semi-gloss or dull enamel finish. Unless
otherwise specified, all aluminum not intended to make electrical contact shall be treated. For guidance on finishes
see 6.6.
3.1.2.4 Pure tin. The use of pure tin, as an underplate or final finish, is prohibited both internally and externally.
Tin content of switch components and solder shall not exceed 97 percent, by mass. Tin shall be alloyed with a
minimum of 3 percent lead, by mass (see 6.8).
3.1.3 Maintainability. Provisions shall be made for rapid checkouts of the equipment using standard test
equipment only. Mounting provisions shall ensure that a minimal amount of maintenance time and effort is required
for removal and replacement, using standard tools only.
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