MIL-DTL-287J
6.5.8 Repeated twist. Repeated twist is the number of cycles through which an assembly can be twisted without
causing mechanical damage or causing the electrical properties to exceed the values specified (see 3.1).
6.5.9 Bending angle. The bending angle in degree/foot can be derived from the minimum centerline radius (in
inches) in 6.5.3 as follows:
The arc length (l) for an arc of "a" degree is l = šra/180°
a = 180° x l/šr = 57.3° x l/r,
Transposing:
But since r is in inches and we wish degree/foot, multiply 57.3° x l/r by 12 and get "a" = 57.3 (12)/r = 687.54/r
6.5.10 Dissimilar metals. Dissimilar metals are defined in MIL-STD-889.
6.6 Cleaning and drying. Waveguide assemblies should be cleaned and dried in accordance with MIL-STD-
2073-1C. Cleaning process should not be injurious to the waveguide assemblies, to humans or to the environment.
Use of toxic chemicals, hazardous substances, or ozone depleting chemicals should be avoided.
6.7 Levels of preservation. Methods of preservation should conform to MIL-STD-2073 requirements.
Preservatives should not be used. Water vapor-proof barrier material should be used to cover the open ends of
each assembly. Barrier material should extend back from each open end and be secured and sealed with tape.
Cross strips should be used to reinforce the barrier material. Alternately, the openings should be sealed with cover
plates or caps and plugs secured with tape. All sealing devices should meet the water vapor-proof requirements of
MIL-PRF-131.
6.8 Subject term (key word) listing.
Bending angle
Load
Cold bending
Microwave
E-plane
Modulator
Finish
Pressurization
Flange
Radio frequency (RF)
Flexure
Retention
H-plane
Rigid
Insertion loss
Twist
Jacket
Voltage standing wave ratio (VSWR)
Length
6.9 Environmentally preferable material. Environmentally preferable materials should be used to the maximum
extent possible to meet the requirements of this specification. As of the dating of this document, the U.S.
Environmentally Protection Agency (EPA) is focusing efforts on reducing 31 priority chemicals. The list of chemicals
and additional information is available on their website at https://www.epa.gov/osw/hazard/wastemin/priority.htm.
Included in the list of 31 priority chemicals are cadmium, lead, and mercury. Use of the materials on the list should
be minimized or eliminated unless needed to meet the requirements specified herein (see section 3).
6.10 Tin whisker growth. The use of alloys with tin content greater than 97 percent, by mass, may exhibit tin
whisker growth problems after manufacture. Tin whiskers may occur anytime from a day to years after manufacture
and can develop under typical operating conditions, on products that use such materials. Conformal coatings applied
over top of a whisker-prone surface will not prevent the formation of tin whiskers. Alloys of 3 percent lead, by mass,
have shown to inhibit the growth of tin whiskers. For additional information on this matter, refer to ASTM-B545
(Standard Specification for Electrodeposited Coatings of Tin).
6.11 Changes from previous issue. The margins of this specification are marked with vertical lines to indicate
where changes from the previous revision were made. This was done as a convenience only and the Government
assumes no liability whatsoever for any inaccuracies in these notations. Bidders and contractors are cautioned to
evaluate the requirements of this document based on the entire content irrespective of the marginal notations and
relationship to the last previous issue.
14
For Parts Inquires submit RFQ to Parts Hangar, Inc.
© Copyright 2015 Integrated Publishing, Inc.
A Service Disabled Veteran Owned Small Business