The M28840 connector series is designed in accordance with the MIL-DTL-28840 military specification, providing high-density, environmentally resistant, circular connectors primarily used in naval shipboard and other harsh environment applications. Engineered for performance and reliability in demanding conditions, these connectors offer exceptional durability, high contact density, and superior resistance to environmental factors such as moisture, salt spray, and vibration.
Features
Shell Style: Available in various mounting styles including wall mount receptacles, jam nut receptacles, and straight plugs to accommodate different installation requirements.
Coupling Mechanism: Quick-disconnect, breech coupling mechanism with a double-start Acme thread for secure and rapid mating.
Durability: Rated for a minimum of 500 mating cycles, ensuring long-term reliability in demanding applications.
Environmental Resistance: Designed to withstand harsh marine environments, including exposure to salt spray, humidity, and temperature extremes.
EMI/RFI Shielding: Excellent electromagnetic interference shielding through conductive materials and shell-to-shell continuity.
Sealing: Features interfacial seals and rear grommet seals to prevent the ingress of moisture and contaminants, meeting the sealing requirements of MIL-DTL-28840.
High-Density Contact Arrangements: Offers a wide range of insert arrangements with high contact densities for efficient use of space.
Specifications
Mechanical
Shell Sizes: Available in sizes 15, 17, 19, 21, 23, 25, 29, 31, 33, 35, and 37.
Contact Arrangements: Multiple configurations as per MIL-STD-1560, supporting a mix of signal, power, and shielded contacts.
Materials:
Shells: Manufactured from high-strength aluminum alloy or stainless steel for corrosion resistance.
Finishes:
Classes:
G: Cadmium plating with olive drab chromate finish on aluminum shells for corrosion resistance.
N: Electroless nickel plating on aluminum shells for high conductivity and durability.
Insulators: Made from high-grade thermosetting or thermoplastic materials resistant to high temperatures and chemicals.
Contacts: Copper alloy contacts with gold plating to ensure optimal electrical 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.
Voltage Rating: Operating voltage up to 600 V RMS at sea level for most configurations.
Contact Resistance: Low resistance to minimize voltage drop and power loss across contacts.
Insulation Resistance: Minimum of 5,000 MΩ under standard atmospheric conditions.
Dielectric Withstanding Voltage: Meets or exceeds the requirements specified in MIL-DTL-28840 to ensure safety and reliability.
Environmental
Temperature Range: Operating temperatures from -55°C to +125°C, suitable for a wide range of environmental conditions.
Corrosion Resistance:
Aluminum shells with cadmium plating: Resistant to 500 hours of salt spray.
Stainless steel shells: Resistant to over 1,000 hours of salt spray.
Vibration and Shock: Designed to withstand severe vibration and shock as per MIL-DTL-28840, suitable for naval and marine environments.
Fluid Resistance: Resistant to fuels, lubricants, hydraulic fluids, and cleaning solvents common in military applications.
Sealing: Environmental and pressure sealing to prevent ingress of moisture, dust, and other contaminants.
Contact Types
Standard Signal Contacts: Sizes 22D, 20, 16, and 12 for transmitting electrical signals and low to moderate currents.
Power Contacts: Larger contact sizes for higher current applications.
Shielded Contacts:
Coaxial Contacts: For RF signal transmission, supporting various coaxial cable types.
Twinax/Triax Contacts: For differential signal transmission with high noise immunity, used in data bus applications.
Fiber Optic Contacts: For high-speed data communication with immunity to EMI/RFI interference.
Hermetic Sealed Contacts: Glass-sealed contacts for applications requiring airtight sealing.
Part Number Breakdown
The M28840 connector part number follows the MIL-DTL-28840 standard format:
M28840 / XX X X X X - XXXX
│ │ │ │ │ │ └─ (6) Polarization Position (A, B, C, D, E)
│ │ │ │ │ └─────── (5) Shell Size and Insert Arrangement
│ │ │ │ └───────── (4) Contact Type (P = Pin, S = Socket)
│ │ │ └─────────── (3) Class (G, N, K)
│ │ └───────────── (2) Shell Style (A = Plug, B = Receptacle, etc.)
│ └─────────────── (1) Specification Sheet Number
└───────────────────────── Military Specification Identifier
Codes Explained
Specification Sheet Number: Identifies the specific connector style and performance requirements.
Shell Style:
A: Straight Plug.
B: Wall Mount Receptacle.
C: Jam Nut Receptacle.
Class:
G: Aluminum shell with cadmium plating.
N: Aluminum shell with electroless nickel plating.
K: Stainless steel shell, passivated.
Contact Type:
P: Pin contacts (male).
S: Socket contacts (female).
Shell Size and Insert Arrangement: Specifies the shell size and contact configuration as defined in MIL-STD-1560.
Polarization Position: Keying positions designated by letters (A, B, C, D, E) to prevent mismating.
Example
Part Number: M28840/07B1G1A-B15SA
M28840/07: Specification sheet for connector type.
B: Wall Mount Receptacle.
1: Modification code (if applicable).
G: Aluminum shell with cadmium plating.
1A-B15S: Shell size 15 with insert arrangement, socket contacts.
A: Polarization position A.
Mounting and Termination
Mounting Styles:
Wall Mount Receptacle:
Front or rear panel mounting options with flange mounting holes.
Provides secure installation on equipment panels or bulkheads.
Includes sealing features for environmental protection at the mounting interface.
Jam Nut Receptacle:
Rear panel mounting with a jam nut for secure attachment.
Ideal for applications with limited front panel space.
Straight Plug:
Connects with receptacles to complete the connection.
Includes coupling mechanisms for secure mating.
Termination Methods:
Crimp Removable Contacts:
Allows for easy assembly and field maintenance.
Standard crimp tools are used for contact termination.
Accessories:
Backshells:
Provide strain relief and protect the wire terminations.
Available in configurations that support EMI/RFI shielding and environmental sealing.
Protective Caps:
Used to protect unmated connectors from environmental exposure.
Available with attachment lanyards for convenience.
Insertion/Extraction Tools:
Specialized tools designed for safe installation and removal of contacts.
Polarization Positions
To prevent mismating in systems with multiple connectors, the M28840 series offers five keying positions designated by letters:
Positions: A, B, C, D, E.
These keying positions alter the orientation of the keyways to ensure that connectors mate only with matching counterparts, enhancing system reliability by avoiding incorrect connections.
Applications
Naval and Marine: Shipboard systems, submarines, and offshore platforms where exposure to harsh marine environments is common.
Military Ground Systems: Ground vehicles and stationary equipment requiring durable and reliable connectors.
Aerospace: Aircraft avionics and systems where environmental resilience is essential.
Industrial: Heavy machinery, robotics, and automation systems operating in challenging conditions.
Communication Systems: Secure and reliable connections for data and signal transmission in critical applications.
Advantages
High Reliability: Engineered to meet stringent military specifications for performance in extreme environments.
Environmental Resistance: Designed to withstand moisture, salt spray, and temperature variations typical in naval applications.
Ease of Maintenance: Removable contacts and standardized tooling simplify assembly and repairs.
EMI/RFI Protection: Effective shielding ensures signal integrity in environments with high electromagnetic interference.
Versatility: Multiple configurations and options to meet specific application requirements.
Compliance and Standards
MIL-DTL-28840: Conforms to all mechanical, electrical, and environmental requirements specified in the military standard for high-density circular connectors.
MIL-STD-1560: Defines standard insert arrangements and contact configurations for interoperability.
MIL-STD-1344: (Superseded by EIA-364) Used for testing electrical connectors to ensure they meet military performance requirements.
MIL-STD-202: Establishes test methods for electronic and electrical component parts.
RoHS Compliance: Certain finishes and materials comply with environmental directives restricting hazardous substances.
Accessories
Backshells:
Provide mechanical protection and strain relief for cables.
Options for environmental sealing and EMI/RFI shielding are available.
Protective Caps:
Shield connectors from contaminants when not in use.
Available in various materials and finishes to match connectors.
Cable Adapters:
Facilitate the transition between different cable types and connector interfaces.
Sealing Gaskets:
Used to enhance environmental sealing at the mounting interface.
Insertion/Extraction Tools:
Essential for proper installation and removal of contacts without damage.
Tools designed per MIL-I-81969/14 and /15 specifications.
Conclusion
The M28840 series connectors are robust, high-density circular connectors designed for the most demanding military and marine applications. Complying with the MIL-DTL-28840 specification, they offer exceptional environmental resistance, reliability, and performance. Their versatile configurations, combined with a wide range of accessories, make them ideal for use in harsh environments where secure and dependable connections are critical. Engineers and system designers can rely on M28840 connectors to meet the rigorous demands of modern naval and military technology.