MIL-DTL-17H Detailed Specification: Cables, Radio Frequency, Flexible and Semi-Rigid

A military standard developed by the United States Department of Defense, "MIL-DTL-17H Detailed specification: cables, radio frequency, flexible and semi-rigid," describes a procedure for flexible and semi-rigid cables with solid and semi-rigid dielectric cores having single, double, and twin inner conductors. Cables covered by this specification are primarily intended for use as transmission lines for the continuous or intermittent transmission of energy in simple power transfer. In general, these cables are designed for low-loss, stable operation from relatively low frequencies to higher frequencies in the microwave and radar regions of the frequency spectrum. The cables may also be used as circuit elements, delay lines, or impedance matching devices. These cables are supplied under a reliability assurance program specified in this standard.

Cables are classified into the following types in this standard:

• Flexible, coaxial single conductor: A flexible coaxial cable consists of a single inner conductor coated with flexible low-loss, RF dielectric core material, which is then surrounded by a braided outer conductor, the whole covered with a protective coating. In some cases, this is covered with an additional braided armour for use in extremely harsh applications. Each element of the cable is designed to contribute to the requirements of the finished product.
• Semi-rigid, coaxial single conductor: Semi-rigid coaxial cables consist of a single inner conductor encased in flexible low-loss, RF dielectric core material and then surrounded by a solid, continuous, metallic outer conductor.
• Two-conductor: The individual dielectric cores of two-conductor cables shall meet the requirements for solid or semi-solid dielectric cores. One wire of one of the inner conductors shall be coded for identification and shall be visible without disturbing the stranding. That is, if all the wires of the inner conductors are coated, then one wire shall be bare, or if all the wires are bare, then one wire shall be coated.
  • Twin cables must be constructed of individual inner conductors within individual dielectric cores within a common outer conductor, or may have individual inner conductors within a common outer core which may be round filled.
  • A pair cable must be constructed from individual coaxial wires contained within a common outer conductor.
• Triaxial: Triaxial cables are manufactured in the same way as regular coaxial cables, except that an additional interlayer of dielectric material is placed over the outer conductor, and an extra shield is placed over that, and the whole thing is covered with a protective coating.

Individual product requirements must be as specified in this standard and in accordance with the applicable technical specification sheet. In the event of any conflict between the requirements of this technical specification and the technical specification sheet, the latter shall prevail.

The classification of requirements for the cable is given in the table titled “Classification of requirements” as follows:

• Qualification: Cables supplied under this specification shall be products authorized by the qualified activity to be listed on the applicable qualified products list prior to contract award. The manufacturer shall establish and maintain a system to meet the requirements of MIL-STD-790 and the requirements herein. Evidence of such compliance shall be verified by the qualified activity as a prerequisite for qualification and maintenance of qualification. After qualification, the manufacturer shall propose a design/construction change plan if:
  • Makes design changes or process changes to the qualified product
  • Tries to use alternative/substitute materials
  • If they try to use alternative suppliers/vendors
• Materials: Unless otherwise specified, materials for major components of the cable shall be as specified herein. Prior approval to use a substitute material shall be obtained from the qualification activity. When no specific material is specified, a material shall be used that will ensure that the finished products meet the performance requirements of this specification. Acceptance or approval of any component material shall not be construed as a guarantee of acceptance of the finished product. Recycled, recovered, environmentally preferable or biobased materials shall be used to the maximum extent possible, provided that the material meets or exceeds operational and maintenance requirements and promotes economic and advantageous life cycle costs.
• Design and construction: Unless otherwise specified, cables shall be of the design and construction specified herein. Inner conductors shall be solid, stranded, stranded or stranded, bare or coated, as specified. Materials and coatings shall be as specified. The material used in the specified dielectric cores shall be of uniform thickness, consistent with the electrical, environmental, physical, mechanical and dimensional requirements. Solid dielectric cores shall be extruded or wrapped with tape and coated with talc when specified. Semi-solid, air-gapped dielectric cores shall be constructed so that the air gaps are an essential element of the construction. Outer conductors or extra shields shall be stranded or solid (tubular) as specified. Barrier tapes, when specified, shall be tightly applied and shall extend smoothly over the outer conductor. Interlayers, when specified, shall be tightly applied and shall be smoothly applied over the outer conductor.
• Visual and mechanical inspection: When cables are inspected and tested as specified in this standard, the visual and mechanical properties shall be as specified.
• Operational: Unless otherwise stated, the operational requirement shall be as specified herein (continuity, spark test, voltage withstand, insulation resistance, corona extinction voltage, characteristic impedance, RF transmission loss (attenuation), standing wave ratio (return loss), capacitance, capacitance stability, capacitance unbalance, transmission unbalance, mechanically induced noise voltage, time delay, aging stability, stress crack resistance, outer conductor integrity and many more).
• Marking: Cables should be marked with JAN brand, defense specification number, manufacturer code, symbol or name and date code in accordance with the essential requirements of MIL STD-1285 standard.
• Weight: When cables are tested to this standard, the maximum weight of the completed cable structure shall be as specified.
• Workmanship: All cables shall be manufactured and processed to be uniform in quality and free from burrs, mould marks, crack marks, foreign matter and other defects which will affect its life, serviceability or appearance. Workmanship shall be such as to ensure that the cable meets the applicable requirements of this specification.

Our organization, which has been trying to support businesses from every sector with its testing, measurement, analysis and evaluation studies carried out in a wide range for years, has a strong staff that closely follows the developments in the world in the field of science and technology and constantly improves itself. In this context, testing services are also provided to businesses in accordance with the "General Specification for Cables, Radio Frequency, Flexible and Semi-Rigid - FSC" standard.