D38999/20 MIL-DTL-38999 Series III Wall Mount Receptacle Connector
Overview
The D38999/20 connector is a Wall Mount Receptacle within the MIL-DTL-38999 Series III family of high-performance circular connectors. Designed for military, aerospace, and other demanding applications, these connectors provide robust and reliable interconnections. The Series III connectors are renowned for their enhanced durability, high contact density, excellent resistance to harsh environmental conditions, and superior electromagnetic interference shielding.
Features
Shell Style: Wall Mount Receptacle designed for front-panel mounting, providing secure and robust installation.
Coupling Mechanism: Self-locking, triple-start threaded coupling for quick and reliable mating with anti-decoupling mechanisms.
Durability: Rated for a minimum of 500 mating cycles, with many applications achieving up to 1,500 cycles.
Environmental Resistance: Withstands extreme temperatures, vibration, shock, and exposure to various fluids and environments.
EMI/RFI Shielding: Superior electromagnetic interference shielding through conductive materials and shell-to-shell continuity.
Sealing: Interfacial and rear grommet seals prevent moisture and dust ingress, meeting environmental sealing requirements of MIL-DTL-38999.
High-Density Contact Arrangements: Offers a wide range of insert arrangements accommodating a high number of contacts in compact shells.
Specifications
Mechanical
Shell Sizes: Available in sizes 9, 11, 13, 15, 17, 19, 21, 23, and 25.
Contact Arrangements: Multiple configurations as per MIL-STD-1560, supporting various combinations of contact sizes and types.
Materials:
Shells: Manufactured from aluminum alloy (standard), corrosion-resistant stainless steel, or lightweight composite materials.
Finishes:
Class W: Olive Drab Cadmium over Nickel plating on aluminum shells for corrosion resistance and electrical conductivity.
Class F: Electroless Nickel plating on aluminum shells for high conductivity and a durable, smooth finish.
Class Z: Black Zinc Nickel plating on aluminum shells, providing a RoHS-compliant, non-reflective finish.
Class K: Passivated stainless steel shells for excellent corrosion resistance without additional plating.
Class M: Nickel PTFE plating on aluminum shells for enhanced corrosion resistance and a non-reflective surface.
Insulators: High-grade thermoplastic materials resistant to high temperatures and chemicals.
Contacts: Copper alloy contacts with gold plating for optimal conductivity and corrosion resistance.
Electrical
Current Rating (dependent on contact size):
Size 22D: Up to 5 A.
Size 20: Up to 7.5 A.
Size 16: Up to 13 A.
Size 12: Up to 23 A.
Size 8: Up to 46 A.
Voltage Rating: Operating voltage up to 500 V RMS at sea level for most configurations.
Contact Resistance: Low resistance values to minimize voltage drop and power loss.
Insulation Resistance: Minimum of 5,000 MΩ at 25°C under standard atmospheric conditions.
Dielectric Withstanding Voltage: Tested per MIL-DTL-38999 to ensure connectors can withstand specified voltages without breakdown.
Environmental
Temperature Range: Operating temperatures from -65°C to +200°C, depending on shell material and finish.
Corrosion Resistance:
Aluminum shells with cadmium plating: Resistant to 500 hours of salt spray.
Stainless steel shells: Resistant to 1,000 hours of salt spray.
Vibration and Shock: Designed to withstand high levels of vibration and shock per MIL-DTL-38999 requirements, suitable for aircraft and ground vehicle environments.
Fluid Resistance: Resistant to fuels, lubricants, hydraulic fluids, and cleaning solvents commonly encountered in military and aerospace environments.
Sealing: Environmental sealing to prevent ingress of moisture and particulates per the requirements of MIL-DTL-38999.
Contact Types
Standard Signal Contacts: Sizes 22D, 20, 16, 12, and 8 for transmitting electrical signals and low to moderate currents.
Power Contacts: Larger contact sizes for applications requiring higher current capacity.
Coaxial Contacts: For transmission of RF signals with sizes accommodating various coaxial cable types.
Twinax/Triax Contacts: For differential signal transmission with high noise immunity, used in data bus and Ethernet applications.
Fiber Optic Contacts: For high-speed data communication with immunity to electromagnetic interference.
The D38999/20 connector part number follows the MIL-DTL-38999 standard format:
D38999/20 W A 35 P N
│ │ │ │ │ └─ Polarization Position (N, A, B, C, D)
│ │ │ │ └─── Contact Type (P = Pin, S = Socket)
│ │ │ └────── Insert Arrangement Number (per MIL-STD-1560)
│ │ └──────── Shell Size Code (A = 9, B = 11, ..., J = 25)
│ └────────── Material/Finish Class (W, F, Z, K, M)
└─────────────────── Military Specification Identifier
Codes Explained
Material/Finish Class:
W: Aluminum shell with Olive Drab Cadmium over Nickel plating.
F: Aluminum shell with Electroless Nickel plating.
Z: Aluminum shell with Black Zinc Nickel plating.
K: Stainless steel shell, passivated.
M: Aluminum shell with Nickel PTFE plating.
Shell Size Codes:
A: Size 9.
B: Size 11.
C: Size 13.
D: Size 15.
E: Size 17.
F: Size 19.
G: Size 21.
H: Size 23.
J: Size 25.
Insert Arrangement Number: Specifies the arrangement and size of contacts as defined in MIL-STD-1560.
Contact Type:
P: Pin contacts (male).
S: Socket contacts (female).
Polarization Position:
N: Normal.
A, B, C, D: Alternate rotational positions to prevent mismating.
Example
Part Number: D38999/20WA35PN
D38999/20: Wall Mount Receptacle connector.
W: Olive Drab Cadmium over Nickel finish on aluminum shell.
A: Shell size 9.
35: Insert arrangement number 35.
P: Pin contacts.
N: Normal polarization (keying position).
Mounting and Termination
Mounting Style:
Wall Mount Front-Panel Mounting:
Secured to the panel using a flange with mounting holes and appropriate hardware (e.g., screws or bolts).
Provides a sturdy and permanent installation on the front panel of equipment.
Includes sealing features such as gaskets or O-rings for environmental sealing at the panel interface.
Termination Methods:
Crimp Removable Contacts:
Allows for easy installation and maintenance.
Contacts are crimped to wires using standardized crimping tools (e.g., M22520/1-01).
Solder Contacts:
Permanent connection where contacts are soldered directly to wires.
Common in fixed installations where maintenance access is limited.
Accessories:
Backshells:
Provide strain relief, shielding, and environmental sealing at the cable exit.
Available in various styles per AS85049 specifications.
Protective Caps:
Shield connectors from environmental exposure when not mated.
Insertion/Extraction Tools:
Specialized tools used to install and remove contacts without damaging the connector or contacts.
Polarization Positions
To prevent mismating in applications with multiple similar connectors, the D38999/20 offers five keying (polarization) positions:
Positions: N (Normal), A, B, C, D.
Each polarization position alters the angular relationship between the master key/keyway and minor keys/keyways. The specific angular positions vary by shell size and are defined in MIL-DTL-38999. This ensures that only connectors with matching keying can mate, preventing incorrect connections.
Applications
Military and Defense: Communication systems, ground vehicles, aircraft avionics, missile systems, and electronic warfare equipment.
Aerospace: Commercial and military aircraft systems, satellites, space exploration equipment, and avionics.
Industrial: Robotics, automation equipment, and machinery operating in harsh environments.
Marine and Offshore: Naval vessels, submarines, offshore drilling platforms, and oceanographic equipment.
Transportation: High-speed trains, heavy trucks, and emergency response vehicles requiring reliable connectivity.
Advantages
High Reliability: Designed to meet rigorous MIL-DTL-38999 specifications for performance under extreme conditions.
Compact and Lightweight: High contact density reduces size and weight, critical in aerospace and portable applications.
Versatility: Wide range of configurations, materials, and finishes to suit specific application requirements.
Ease of Maintenance: Removable crimp contacts and standardized tools simplify repairs and maintenance.
Environmental Protection: Sealed against moisture, dust, and fluids, ensuring long-term durability in harsh environments.
EMI/RFI Protection: Excellent shielding effectiveness to maintain signal integrity in environments with high electromagnetic interference.
Compliance and Standards
MIL-DTL-38999 Series III: Conforms to all mechanical, electrical, and environmental requirements specified in MIL-DTL-38999 for Series III connectors.
MIL-STD-1560: Defines standard insert arrangements and contact configurations for consistent interoperability.
AS85049: Governs specifications for connector accessories, including backshells, strain reliefs, and protective covers.
RoHS Compliance: Certain finishes, such as Black Zinc Nickel (Class Z), comply with the Restriction of Hazardous Substances directive for environmentally sensitive applications.
Other Standards:
Tested per applicable sections of MIL-STD-1344 (superseded by EIA-364) for electrical and mechanical performance.
Environmental testing as per MIL-STD-810 for resistance to temperature, humidity, vibration, and shock.
Accessories
Backshells:
Provide mechanical strain relief and protection for cables.
Options for EMI/RFI shielding and environmental sealing.
Protective Caps:
Dust caps to protect connectors when unmated.
Available with lanyards for tethering to equipment.
Heat Shrink Boots:
Offer environmental sealing and mechanical protection at the cable exit point.
Used in conjunction with backshells for a complete sealing solution.
Insertion/Extraction Tools:
Tools designed per MIL-I-81969/14 and /15 specifications.
Essential for proper installation and removal of contacts without damage.
Conclusion
The D38999/20 Wall Mount Receptacle is a versatile and reliable connector solution engineered to meet the stringent requirements of military and aerospace applications. Its robust construction, environmental resilience, and adaptability to various configurations make it an ideal choice for systems where performance and reliability are critical. By conforming to the MIL-DTL-38999 Series III specifications, these connectors ensure compatibility and interoperability across a wide range of equipment and platforms, providing secure and dependable connections in the most demanding environments.