Features and Application

MIL-DTL-38999 Series II connectors feature a bayonet coupling mechanism with lower profile design and rear-removable crimp contact retention system.

These connectors were designed for military and commercial applications where the prime requirements are lower profile and lighter weight.

Reduction of both size and weight were achieved through the use of thinner shell walls and length restrictions. These design restrictions reduced the RFI attenuation characteristics
and the “scoop” protection, while yielding an excellent general purpose, lightweight connector. Compared to Series I, Series II connectors achieve up to 20% reduction in mated pair length, up to 39% reduction in outside diameter and
up to 40% reduction in weight (128 pin mated pair).

This family of connectors is offered in six receptacle-mounting styles. They include square flange receptacles, for both front and rear panel (wall) mounting; square flange receptacles, for both front and rear panel (box) mounting; square flange
receptacle with extended grommet, for front of panel (box) mounting; and jam nut receptacles which incorporate “ O” ring seals, designed for rear panel “D” hole mounting.

Plugs are available in two designs, with and without RFI grounding.

Fifty-two insert arrangement per MIL-STD-1560 are tooled and qualified to MIL-DTL-38999 Series II, utilizing 3 to 128 M39029 contacts. Contacts come in sizes 22D, 22M, 22, 20, 16 and 12, terminating wire sizes from 28 to 12 gauge.

These connectors are available in wide range of shell materials and finishes. Aluminum shells are offered in electroless nickel, bright cadmium, anodized, and olive drab cadmium. Other finishes such as zinc cobalt are available upon request
to commercial callouts only. In addition, we offer passivated stainless steel shells with standard environment-resisting inserts (commercial callouts only).



Universal I/R Tool – A single, expendable plastic tool is used for both insertion and removal of contacts.

Closed-Entry Socket Insert – Hard dielectric socket face has lead-in chamfers for positive alignment of pins (even partially bent within pre-established limits) with sockets.

Interfacial Pin Insert Seal – Raised moisture barriers around each pin, which mate into lead-in chamfers of hard face socket insert, provide individual contact sealing. Interfacial seal is never touched by service tools.

Elastomer Wire Sealing Grommet – Sealing over a wide range of wire diameters is assured by a triple wire seal in each cavity at the rear of the connector.

Superior Contact Stability – Rear release crimp contact system features a stamped beryllium-copper retaining clip captivated by molded-in shoulders of each contact cavity in the insulator. A rear-inserted M81969 plastic tool expands the tines beyond the shoulder, releasing the contact.

Shell Polarization – Alternate key/keyway positions prevent cross mating of adjacent connectors having same insert arrangement.