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.

Operating Temperature Range
Finish B: -65°C to +175°C (-85°F to +347°F)
Finishes C and F: -65°C to +200°C (-85°F to +392°F)
Finish A: -65°C to +150°C (-85°F to 302°F)

Material and Plating Data (Finish)
B – aluminum shell, olive drab cadmium over nickel base
C – aluminum shell, black anodized finish
F – aluminum shell, electroless nickel finish
A – aluminum shell, silver to light iridescent yellow color
(bright) cadmium over electroless nickel base

Corrosion Resistance
Finishes A, B and C withstand 500-hour salt spray.
Finish F withstands 48-hour salt spray.

Durability
Mated connectors withstand a minimum of 250 mating cycles for RFI plug (MS27484) and 500 cycles for MS27473 and MS27500 plugs.

Environmental Seal
Wired, mated connectors with specified accessories attached, shall meet the altitude-immersion test specified by MIL-DTL-38999.

Fluid Resistance
Connectors resist specified immersions in MIL-PRF-7808, MIL-PRF-23699, MIL-PRF-5606, M2-V Chevron oil, Coolanol 25, MIL-DTL-83133 (JP-8), MIL-DTL-5624 (JP-4, JP-5), SAE-AMS1424 Type I, and other solvents and cleaning agents.

Shell-to-Shell Conductivity
Maximum potential drop shall not exceed:
• With RFI spring fingers, finish F = 1.0 millivolt, while finishes A and B = 2.5 millivolts.
• Without spring fingers = 200 millivolts.
• Finish C = nonconductive.

Shielding Effectiveness
RFI and EMI attenuation at the specified frequencies meet the requirements of MIL-DTL-38999.
• RFI shielding effectiveness of mated connectors with RFI backshells is measured in a triaxial radio frequency leakage fixture.
• EMI shielding effectiveness is measured at the interface of mated connectors and tested by the mode-stirred technique specified in method 3008 of MIL-STD-1344.

Shock and Vibration Requirements
Wired, mated connectors shall not be damaged, nor shall
there be a current interruption longer than one microsecond
when subjected to the following:

Standard Shock
Mated connectors withstand a pulse of approximate half
sine wave of 300 G magnitude with duration of three
milliseconds applied in three axes per MIL-STD-1344,
method 2004.

Vibration
Mated connectors withstand the following vibration levels:
• Random vibration per MIL-STD-1344, method 205 test
condition VI, Letter “J”.