MIL-DTL-38999 Series III

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High-Performance, Self-Locking Cylindrical Connectors for Harsh Environments

Elimec USA offers the MIL-DTL-38999 Series III—the most advanced cylindrical connector in the MIL-DTL-38999 family, engineered for demanding military, aerospace, and high-performance industrial environments. Designed for reliability under extreme conditions, Series III connectors feature a quick “one-turn” self-locking acme-thread coupling system and superior mechanical strength.

 Key Features & Benefits

• One-Turn Self-Locking Coupling
  Fast, secure mating with a durable acme thread system. The self-locking design eliminates the need for lockwiring and reduces the risk of cross-threading.
• Superior Mechanical Strength
  Thicker shell walls, greater coupling surface area, and metal-to-metal bottoming provide excellent resistance to shock, vibration, and wear.
• Scoop-Proof Design
  Elongated shells with recessed contacts prevent pin damage during blind mating.
• Interchangeable with MIL-SPEC Receptacles
  Elongated mounting holes enable backward compatibility with a variety of flange-mount receptacles, making Series III a perfect upgrade path.
• Extensive Shell & Insert Options
  Available in 9 shell sizes and 54 insert arrangements using M39029      contacts, including size 8 twinax for high-speed data applications.
• Firewall Protection
  Offered with stainless steel shells in K and S class, meeting      firewall requirements for high-heat or hazardous applications.
• Rear-Release Crimp Contacts
  Industry-standard M81969 plastic tools allow simple insertion and removal of contacts while maintaining secure retention.
• Full Environmental Sealing
  Triple-sealed elastomer grommets and interfacial seals around each pin ensure rugged moisture and dust protection.

 Materials & Finishes

• Aluminum Shells:
  • Class F: Electroless nickel
  • Class T: Nickel fluoro-carbon polymer
  • Class W: Olive drab cadmium
  • Class Z, ZC: Zinc-nickel / zinc-cobalt (RoHS)
  • Class BN: Black nickel (RoHS)
• Stainless Steel Shells:
  • Class K: Passivated, firewall rated
  • Class S: Electrodeposited nickel, firewall rated
• Nickel-Aluminum-Bronze Shells:
  • Class BZ: Highly corrosion-resistant (RoHS)

Shock & Vibration Resistance

• Standard Shock:
  300G ±15% pulse, 3 ms, in 3 axes (MIL-STD-1344)
• High-Impact Shock:
  Passes MIL-S-901 Grade A – 400 lb. hammer drop from 1 ft., 3 ft., and 5 ft. (3 axes)
• Vibration Testing:
  • Sine vibration: 10–2,000 Hz in 3 axes
  • Random vibration: MIL-STD-1344 Method 2005, Conditions V & VI ("J")

Electrical & Environmental Performance

• Operating Temperature:
  • Classes F, K, S, BZ: –65°C to +200°C
  • Classes W, T, Z, BN, ZC: –65°C to +175°C
• Corrosion Resistance:
  • 500-hour salt spray (Classes K, S, W)
  • 48-hour salt spray (Class F)
  • RoHS classes vary—consult factory for details
• Shell-to-Shell Conductivity:
  • Class F, S: ≤ 1.0 mV
  • Class W: ≤ 2.5 mV
  • Class K: ≤ 10.0 mV
• Durability:
  • Minimum 500 mating cycles
• Shielding Effectiveness:
      Meets MIL-DTL-38999 RFI/EMI requirements
  • RFI tested in triaxial leakage fixture
  • EMI tested per MIL-STD-1344 Method 3008
• Environmental Sealing:
  Fully sealed mated connectors pass MIL-DTL-38999 altitude immersion test.
• Fluid Resistance:
  Withstands exposure to MIL-PRF-5606, MIL-PRF-7808, Coolanol 25, JP-8, JP-5, and various cleaning agents.