MIL-DTL / MIL-C / MILITARY CONNECTOR SPECIFICATIONS EXPLAINED
Connectors required for Military/Defence equipment, particularly those providing an in and out (I/O) equipment interface, are required to meet a number of strict quality and safety standards, many of which were defined originally by the US Department of Defence. Frequently using many technical terms which can sometimes be hard to decipher the standards applied to connectors are commonly known as Military Standard, MIL-STD, or MIL-SPEC connectors. Such connectors need to survive in rugged environments found in military vehicles, aircraft, naval vessels and mobile equipment and are specially designed for durability and resistance to vibration, corrosion, ingress of dust and water etc. depending on the application. Connectors meeting such stringent requirements are now also commonly used in commercial applications such as security, renewables, industrial and oil and gas applications. The use of standard specifications provides a common set of features and performance across different manufacturers, helping define suitable mating halves for system integration and spares for in-service maintenance and repairs.
With 50+ years of experience in the supply of MIL, Defence and Hi-Rel connectors, Lane Electronics has a wealth of experience in providing best in class connectors for such rugged applications. To better understand the requirements of MIL standards and the various connector options that meet them we have published a useful overview for our customers.
QPL (Qualified Products List)
The Qualified Products List (QPL) is a list of Products and manufacturers against defined product criteria. It presents products that are defined by standard parameters, where supply is independently verified to meet those parameters by those listed manufacturers/suppliers
COTS (Commercial Off The Shelf)
In most cases, equivalents to QPL product are available without the independent verification of standardisation and the acronym COTS for Commercial Off The Shelf is often used to refer to those products. In many cases the manufacturer will produce both QPL product and COTS product alongside each other, using exactly the same materials and processes such that it is equivalent in every way other than maintaining the independent accreditation to achieve QPL status.
Previously known as MIL-C-38999, MIL-DTL-38999 connectors are a series of four connectors featuring either bayonet, threaded or Breech Lok coupling mechanisms. They are high-density, quick-connect, environmentally resistant connectors that use removable contacts and have an operating temperature range of -65°C up to +200°C. Now the most popular circular connector series for high performance applications.
Series I connectors are scoop proof and have bayonet coupling.
Series II connectors are low-profile versions of Series I. The low profile means they are not scoop proof but does make them popular when weight or space is limited.
Series III connectors are coupled by a quick tri-start screw thread, are scoop proof, and are now the most prevalent military circular connector.
Series IV connectors are coupled by a Breech Lok mechanism, are scoop proof, lightweight and suitable for blind mating applications, and they also have high-vibration attributes.
Lane Electronics assemble the SOURIAU MIL-DTL-38999 series 1 (8LT) and SOURIAU MIL-DTL-38999 series 3 (8D) connectors and their COTS equivalents under strict controls and authority of EATON, providing full QPL accredited release from our site.
Previously known as MIL-C-26482, MIL-DTL-26482 are space-efficient bayonet lock connectors. They are high-density, quick-connect, environmentally resistant connectors that use fixed solder and PCB and removable crimp contacts and have an operating temperature range of -55°C up to +125°C. Widely used across many applications and industries, these connectors can provide very cost-effective solutions.
Series I connectors offer solder contacts, are scoop proof and have bayonet coupling.
Series 2 connectors offer removable crimp contacts and are intermateable with equivalent series 1 connectors.
SOURIAU 851 series is the QPL Series 1 range and the SOURIAU 852 series is the QPL Series 2 range of connectors, manufactured by EATON.
Previously known as MIL-C-5015, MIL-DTL-5015 connectors represents one of the original circular connectors for military applications. They are medium-density, environmentally resistant connectors that use fixed solder and PCB contacts and removable crimp contacts and have an operating temperature range of -55°C up to +125°C. The specification defines a screw-thread coupling while a popular derivative, utilising the same materials and contact arrangements, provides a secure quick-connect reverse bayonet-coupling.
The Weald Electronics LMJ series of connectors is the COTS equivalent screw-coupling version.
These products are extensively stocked and distributed by Lane Electronics.
Previously known as MIL-C-24308, MIL-DTL-24308 represents non-environmental, polarised shell, rack and panel, miniature connectors with pin and socket, solder (non-removable), insulation displacement (non-removable), or crimp (removable) float-mounting or rigid mounting brackets. They have an operating temperature range of -55°C to 125°C.
Also known as D-Subminiature or D-sub connectors, they are probably the most frequently specified connector style in electronics equipment and are used in environments where weight and space are a consideration, whilst accommodating a lot of circuits in relation to their size. For this reason, they are ideal in Military equipment for applications such as missile controls, aircraft, and ground support systems, as well as satellites, video and communication equipment. Besides rack and panel applications, these can also be adapted for cable use by utilising backshells, strain relief clamps and other related accessories.
They are designed for use in military applications as follows: classes G and N are to be used within environments at the operating range of -55°C to 125°C (class N are used in environments where residual magnetism needs to be held at low levels), class H (Hermetic) are used when pressures/vacuums have to be maintained in the boxes/vessels onto which the connectors are mounted, and classes D, K, and M are intended for use in high-reliability space applications.
Lane Electronics Ltd extensively stocks and distributes products from Positronic Industries that covers both the MIL specification and commercial versions of this style of connector.
Previously called MIL-C-83513, the MIL-DTL-83513 specification describes micro-miniature, polarised shell rectangular connectors that have solder or non-removable crimp contacts. They are hard-wearing and long lasting and as such are intended for use in harsh environments, having high dielectric strength, high current capability, low contact resistance, and high resistance to vibration and shock. They are lightweight, of small size, and have a high density of contacts based on a spacing or pitch of of 0.050 inches.
They are also known as Micro-D connectors and due to their small size and weight, are commonly used in radars, shoulder-launched weapons, military GPS, medical equipment, satellites, drilling tools, advanced soldier technology, and aerospace avionics applications.
The comprehensive range of Micro-D connectors manufactured by Glenair is fully supported by Lane Electronics, providing technical support and materials management for all versions with QPL release or COTS equivalents.
Derivatives that are based on similar dimensions but with a metric 2mm or smaller contact pitch are gaining popularity across similar applications. These connector styles typically offer even higher contact density for similar electrical and mechanical performance as defined in MIL-DTL-83513, and many provide additional benefits such as removable crimp contacts.
The heavy-duty rectangular connector standard for designers when an application demands minimal use of space and weight without any sacrifice in the performance. The MIL-DTL-28748 specification ensures the use of high-quality materials, a high resistance to shock and vibration, positive locking, and a long life. This specification is typically used in aerospace, instrumentation and for many types of portable equipment. Previously known simply as M28748, high density and standard density MIL-DTL-28748 product ranges are made up of rectangular rack and panel connectors with non-removable solder contacts and removable crimp contacts.
Available from Lane Electronics, the Positronic SGMC and GMCT series provide cable mount and rack and panel connectors that are qualified to MIL-DTL-28748.
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We hope the information above has been of use in better understanding the various military connector specifications commonly used in the electronic connector industry. If you would like to learn more, or if you have any enquiries about Lane Electronics products or services, please contact us or call +44 (0)1403 790661 to speak to an applications engineer.