MIL-DTL-38999 Series III Circular Connectors, Triple-Start Thread Connectors
Triple-start thread circular connectors, MIL-DTL-38999 series III, are designed for harsh environments with high vibration, dust, and moisture exposure, featuring a fire-resistant housing with multiple coating options for improved durability at elevated temperatures. They have a triple-start thread design with anti-loosening locking for fast and secure mating, together with EMI/RFI shielding, interface sealing, and anti-misalignment protection. These circular connectors are made with housing materials such as aluminum alloy, naval brass, stainless steel, and composite materials depending on application requirements.
Specifications
| Electrical | Current Rating & Contact Resistance | Size 22D (ø 0.76): 5 A, ≤ 12 mΩ Size 20 (ø 1.0): 7.5 A, ≤ 5 mΩ Size 16 (ø 1.6): 13 A, ≤ 2.5 mΩ Size 12 (ø 2.4): 23 A, ≤ 1.5 mΩ Size 10 (ø 3.15): 40 A, ≤ 1.0 mΩ |
| EMI Shielding | 100 MHz to 1 GHz: ≥ 85 dB 1 GHz to 10 GHz: ≥ 90 dB | |
| Dielectric Withstanding Voltage (DWV) | Service Ratings M, I, II, N: 1,000–2,300 V @ Sea Level 600-1,000V@21000m | |
| Insulation Resistance | Normal: ≥ 5,000 MΩ @ 500 VDC Damp heat: ≥ 100 MΩ | |
| Shell-to-Shell Conductivity | Class W: ≤ 2.5 mΩ Class F: ≤ 1.0 mΩ Class K: ≤ 5.0 mΩ | |
| Mechanical | Shell Material | Aluminum Alloy, Stainless Steel, Copper Alloy, Composite |
| Plating | Class W/J: Olive Drab Cadmium Class K: Passivated Class F/M: Electroless Nickel | |
| Insulator | Thermoset | |
| Seals | Silicone Rubber | |
| Contact | Copper Alloy, Gold Plated | |
| Mating cycles | 500 cycles (Metal shell) ≥ 1,500 cycles (Composite shell) | |
| Vibration | Sine: 60 g (with temp cycle/dummy load, 36 h) Random: 44.1 g RMS (high temp) / 49.5 g RMS (ambient) | |
| Mechanical Shock | 300 g, 3 ms, half-sine wave | |
| Contact Retention | Size 22D: 45 N Size 20: 67 N Size 16: 111 N Size 12/10/8: 111 N | |
| Environmental | Operating Temperature | Class W/J: -65 °C to +175 °C Class M/K/F: -65 °C to +200 °C |
| Salt Spray | Class F: 48 h Class W: 500 h Class K: 1,000 h High-Grade: 2,000 h (per MIL-DTL-38999) | |
| Damp Heat (Humidity) | 98% RH @ 40 °C; 10 cycles (within 24 hours) per MIL-DTL-38999K | |
| Operating Altitude | ≤ 30,480 m | |
| Fluid Resistance | Resistant to various fuels, coolants, and solvents |
Features
- Triple-start thread connectors are available with flexible shell options, including multiple materials and coatings for different environmental requirements
- They use a five-key positioning system to enable blind mating and prevent misalignment during installation
- The connectors use a triple-start thread design for fast coupling with an anti-loosening locking mechanism
- Ceramic inserts are used to ensure precise contact alignment during mating
High Wood works with customers across Asia, Europe, the Americas, and other international markets, building long-term partnerships with more than 200 companies worldwide, including Klemsan (Turkey), CPE (Italy), and SUNGJIN (Korea). Backed by over 10 years of experience in the connector industry, we have an R&D team that focuses on practical engineering work, from electrical connector design and structural optimization to detailed drawings, helping customers move smoothly from development to mass production.