MIL-DTL-24640C
3.4 Design and construction.
3.4.1 Component wire. Unless otherwise specified in the applicable specification sheet, finished component
wire shall be in accordance with SAE-AS81044, SAE-AS 81044/9, and SAE-AS81044/12. When specified in the
specification sheet, the color shall be in accordance with MIL-STD-104.
3.4.2 Separators. Separators employed directly over conductors shall be applied to give not less than 100
percent coverage to the conductors.
3.4.3 Insulation. The insulation shall be as specified in the applicable specification sheet. Conductor insulation
shall be readily removable by conventional wire stripping devices without damage to the conductor.
3.4.4 Tapes. Tape wraps over the cable core, shield, and other locations shall be as specified in the applicable
specification sheet. Tapes shall be applied helically with an overlap of not less than 25 percent. From a design
standpoint (Galvanic corrosion), copper foil shall be used where aluminum foils have been used.
3.4.5 Fillers and binders. Fillers and binders may be used to provide firmness and roundness of completed
cables and to provide watertightness when required by the specification sheet. Filler and binder material shall be
compatible with all other cable components. Compatibility of components shall be determined in accordance with
4.7.2 and 4.7.3.
3.4.6 Shields.
3.4.6.1 Component shields. When specified in the applicable specification sheet, shall be of the push back type
and shall be constructed to conform to the physical and electrical requirements specified in the applicable
specification sheet. The shield shall be of a close fitting braid construction and shall be free from irregularities and
discontinuities. Individual wire strands may be spliced, but not more than one carrier may be spliced at any one
point. When the braided shield is cut, it shall be capable of sliding back not less than 4 inches on an exposed 24-
inch length of component wire or cable with the opposite end clamped. When specified in the applicable
specification sheet, braid angle and shield coverage calculations shall be in accordance with NEMA WC 27500.
3.4.6.1.1 Component shield insulation. Shield insulation shall consist of two polyester tapes, Type G in
accordance with MIL-I-631, sealed. Alternate shield insulation may consist of one polyester tape, plus an extruded
jacket of a suitable translucent material, minimum average thickness of the transparent material 0.003 inch. The
standard identification code shall be applied by Method 2 on the inner tape.
3.4.6.2 Overall shields. Overall shields shall be applied to the cable when specified in the applicable
specification sheet. The shield shall be of a close fitting braid construction and shall be free from irregularities and
discontinuities. Individual wire strands may be spliced, but not more than one carrier may be spliced at any one
point. The braid angle shall be no less than 30 degrees, and no greater than 50 degrees. Conformance of the shield
shall be verified by the surface transfer impedance and EMP response requirements of the applicable specification
sheet.
3.4.6.3 Foil shields. When specified in the applicable specification sheet, shall be of the copper/polyester type.
The percent overlap shall be as specified in the applicable specification sheet.
3.4.7 Watertightness. Where watertight cable construction is specified (see 3.1), voids within the cable
construction shall be filled to prevent the passage of water longitudinally through the cable.
3.4.8 Cable jacket. A well-centered jacket shall be applied over the cable core. The jacket shall conform to the
applicable specification sheet and shall be removable without damage to the underlying shield or components.
3.4.9 Finished cable. Finished cable shall conform to the applicable specification sheet. Cable dimensions
shall be measured as specified in 4.6.2.
3.4.9.1 Cabling. The number of component wires shall be as specified in the applicable specification sheet.
The outer layer shall be left hand and in cables with multiple layers of components, the inner layer or layers may be
either right hand or left hand lay. The lay length shall be not less than 8 times nor more than 16 times the diameter
over each individual layer of components.
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