Circular MIL-Spec (Military Specification) connectors feature a cylindrical shell available in various diameters and are designed to attach backshells to the housing using threaded connections. These connectors are typically available as either male (pin) or female (socket) types and utilize solder or removable crimp contacts for connection.
Originally developed in the 1930s for demanding aeronautical and tactical applications, the U.S. Department of Defense adopted these connectors as part of the Type “AN” (Army-Navy) series, which became the standard for modern military circular connectors. Over time, these connectors—along with their advanced iterations—have come to be referred to as Military Standard connectors, or “MIL-STD” (informally known as MIL-SPEC). Today, they are used across a variety of industries, including aerospace, industrial, marine, and automotive applications.
MIL-SPEC connectors are generally plug-type connectors, also known as male connectors, which feature a protruding ferrule to hold and align fibers for mating. These connectors require a mating adapter, designed to fit their securing mechanism, which could be a bayonet, screw-on, or snap-in style. A key performance metric for military connectors is insertion loss, which measures the amount of light lost in the connection, typically expressed in decibels (dB).
A few key details about these connectors include: The four-digit number at the beginning of the part number indicates the type of connector. For example, a 3470 or 3474 will mate with a 3476, but not with each other. The two-digit number that follows represents the shell size, which helps determine the appropriate backshell size. The backshell serves as the area for strain relief loops and for securing a boot. The final number and letter indicate the terminal configuration: ‘S’ stands for Socket and ‘P’ stands for Pin.
Circular Connectors – Mil-Spec, Micro-Miniature, Filter, Sealed, and Custom Options
Amphenol Aerospace offers a range of MIL-Spec qualified connectors, including MIL-DTL-38999 Series I, II, and III; MIL-DTL-26482 Series II; MIL-DTL-83723; MIL-DTL-5015; and MIL-DTL-22992 Class L connectors. In addition to standard MIL-Spec connectors, Amphenol also designs and manufactures specialized options such as high-power connectors, lanyard release or quick disconnect connectors, BACC63 and EN2997 connectors, Dualok high-vibration connectors, connectors with printed circuit board contacts, bulkhead feed-throughs, RoHS-compliant platings, and more. These connectors support a wide range of contact options, including crimp, solder, PC tail, and compliant pin contacts, in sizes ranging from 0 to 22D.
Amphenol’s MIL-DTL-38999 Series II and MIL-STD-26482 Series II connectors are available in Black Zinc Nickel plating, which offers superior durability compared to electroless nickel plating. These connectors are compliant with MIL-DTL-38999, MIL-STD-26482, and AS85049 specifications.
