MIL-DTL-38999 (D38999) High-Density Circular Aerial Connectors Series The MIL-DTL-38999 series is divided into four sub-series: Series I, Series II, Series III, and Series IV. These are the industry-standard military circular connectors designed for harsh environments, offering full interchangeability with domestic and international brands of the same specifications. * **Series I / 2nd Gen:** Bayonet lock mechanism. * **Series III / 4th Gen:** Three-start self-locking thread for rapid connection, featuring a scoop-proof structure to prevent misalignment damage, ideal for blind mating applications. **Shell Sizes:** Available in nine shell sizes: 09#, 11#, 13#, 15#, 17#, 19#, 21#, 23#, and 25#. **Mounting Options:** Wall-mount flange receptacles, nut-lock receptacles, straight plugs, and 90° angled plugs. **Materials & Finishes:** Shell materials include high-strength aluminum alloy, stainless steel, and composite materials. Surface treatments offer cadmium plating (mil-green), electroless nickel, black zinc-nickel passivation, and stainless steel passivation. Features salt spray resistance, vibration/shock resistance, and multi-layer sealing for dust, moisture, and oil protection. **Safety & Compatibility:** Multi-key anti-mate design prevents incorrect insertion across different shell codes. Supports diverse contact arrangements for power, analog signals, high-speed differential signals, and coaxial configurations. **Applications:** Widely used in aerospace, UAVs, radar/military equipment, rail transit, new energy systems, marine exploration, and high-end testing. Fully compatible with major global brands' equivalent series. **Main Shell Models (Industry Standard D38999 System)** **Series I (Bayonet Lock)** * D38999/20 (Square Flange Receptacle) * D38999/24 (Nut-Lock Receptacle) * D38999/26 (Straight Plug) * D389999/20WJ09-09PN * D38999/20WJ11-98PN * D38999/20WJ13-35PN * D38999/20WJ15-19PN * D38999/20WJ17-26PN * D38999/20WJ19-32PN * D38999/20WJ19-32PN * D38999/20WJ19-32PN * D38999/20WJ21-75PN * D38999/20WJ23-61PN * D38999/20WJ25-98PN * D38999/24WJ09-09SN * D38999/24WJ11-98SN * D38999/24WJ13-35SN * D38999/24WJ15-19SN * D38999/24WJ17-26SN * D38999/24WJ19-32SN * D38999/24WJ21-75SN * D38999/24WJ23-61SN * D38999/24WJ25-98SN * D38999/26WJ09-09PN * D38999/26WJ11-98PN * D38999/26WJ13-35PN * D38999/26WJ15-19PN * D38999/26WJ17-26PN * D38999/26WJ19-32PN * D38999/26WJ21-75PN * D38999/26WJ23-61PN * D38999/26WJ25-98PN **Series II (Low-Profile Lightweight Bayonet)** * D389999/27, D389999/28, D38999/29 * D389999/27FJ09-09P * D38999/27FJ13-35P * D38999/27FJ15-19P * D38999/27FJ21-75P * D38999/28FJ09-09S * D38999/28FJ13-35S * D38999/28FJ15-19S * D38999/28FJ21-75S **Series III (Three-Start Thread Self-Locking, Most Common, Includes EMI Shielding Fingers)** * D38999/20, D389999/24, D38999/26 * D38999/20FJ09-09PN * D38999/20FJ11-98PN * D38999/20FJ13-35PN * D38999/20FJ15-19PN * D38999/20FJ17-26PN * D38999/20FJ19-32PN * D38999/20FJ21-75PN * D38999/20FJ23-61PN * D38999/20FJ25-98PN * D38999/24FJ09-09SN * D38999/24FJ11-98SN * D38999/24FJ13-35SN * D38999/24FJ15-19SN * D38999/24FJ17-26SN * D38999/24FJ19-32SN * D38999/24FJ21-75SN * D38999/24FJ23-61SN * D38999/24FJ25-98SN * D38999/26FJ09-09PN * D38999/26FJ11-98PN * D38999/26FJ13-35PN * D38999/26FJ15-19PN * D38999/26FJ17-26PN * D38999/26FJ19-32PN * D38999/26FJ21-75PN * D38999/26FJ23-61PN * D38999/26FJ25-98PN **Series IV (Short Shell Thread Self-Locking, Lightweight)** * D38999/30, D38999/32, D38999/34 * D38999/30ZF15-19P * D38999/30ZF21-75P * D38999/32ZF15-19S * D38999/32ZF21-75S **Code Explanation:** P = Pin (Male Contact); S = Socket (Female Contact). Compatible with various EMI backshells and cable clamp accessories. **Key Features** * Superior electrical shielding performance supporting high-speed signal transmission. * Scoop-proof structure protects pins from assembly damage. * Multi-layer independent sealing ensures oil and humidity resistance. * Easy maintenance with detachable contacts for crimping. * High-strength shell resists vibration and shock. * Comprehensive specifications support mixed contact configurations. * Fully mated IP67 protection rating. * Multiple plating options to meet varying salt spray requirements. **Technical Specifications** * **Standard:** MIL-DTL-38999 (Compatible with domestic GJB599A) * **Connection Type:** Series I/II Bayonet Quick-Lock; Series III/IV Three-Start Thread Self-Lock * **Shell Material:** Aluminum Alloy / Stainless Steel / Modified Composite * **Surface Finish:** Cadmium Plating (Mil-Green, W), Electroless Nickel (F), Black Zinc-Nickel (Z), Stainless Steel Passivation (K) * **Contact Count Range:** 3~128 positions, compatible with #12, #16, #20, #2 2D multi-spec contacts * **Contact Material:** Copper alloy base with gold plating; supports Crimp, Solder, and PCB Straight-Pin types * **Insulator:** High-temp thermoplastic material, Flame Retardant UL94-V0 * **Operating Temperature:** -65°C ~ +175°C (Stainless Steel high-temp version up to 200°C) * **Rated Voltage:** 500V (Signal Contacts)