MIL-DTL-28781E
3.2.3 Cable forming. The twisted pairs shall be assembled to form a substantially cylindrical core.
Adjacent layers may be stranded in the same direction or in opposite directions. For a 104-pair cable, the
cable shall be formed in two 52-pair concentric units or four 26-pair units.
3.2.3.1 Binder. A colored binder shall be applied around the units for separation. The colors shall be
readily recognizable. Bindings shall be applied with a lay of not more than 4 inches. The binder may be
either a non-hygroscopic thread or tape.
3.2.3.2 Binder colors. The colors for each unit binder shall be as follows:
Unit
Color of binding
1
Blue-White
2
Orange-White
3
Green-White
4
Brown-White
5
Slate-White
3.2.4 Core covering. The core covering shall be completely covered with Mylar (Mylar is a
registered trademark of E.I. Dupont Co.), polyethylene, or Mylar backed SBR (Styrene-Butadiene Rubber)
or equivalent, which shall be non-hygroscopic and shall be applied with an overlap. The core covering
shall provide a sufficient heat barrier to prevent visible evidence of conductor insulation deformation or
adhesion between conductors caused by adverse heat transfer during the jacketing operation.
3.2.4.1 Dielectric strength. In each length of completed cable, the insulation between conductors,
and between conductors and shield, shall withstand the dielectric dc potential for 3 seconds as follows:
dc volts
Between conductors
3,600
Between conductors and shield
1,800
3.2.5 Shield. An overall tinned copper braid shield shall be applied over the core-covering. The
shield shall cover 90 percent of the cable core.
3.2.5.1 Shield resistance. The dc resistance of the shield for a 1000-foot (304.8-meter) length of
completed cable shall not exceed the values shown below:
No. of pairs
dc resistance
1
5.75 ohms
3
4.00 ohms
6
3.50 ohms
26
2.10 ohms
3.2.6 Jacket material. The jacket material shall be black colored polyvinyl chloride containing a
minimum of 1 percent of carbon black, or similar material, to resist ultraviolet light. The jacket material
shall conform to the physical (finished cable) requirements outlined in 3.2.6.1 through 3.2.6.4. The cable
jacket shall have a type A durometer hardness of 80±5.
3.2.6.1 Tensile strength. The cable jacket shall have a minimum tensile strength of 2000 pounds per
square inch (psi).
3.2.6.2 Elongation. The cable jacket shall have a minimum elongation of 250 percent.
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