Metal Connector Selection

All connectors shall be of a type and design that provide a low impedance path for the signal line shield to the equipment case. If the signal circuit must be isolated from the equipment case, and if the shielding effectiveness of the case must not be degraded, a connector of a triaxial design that properly grounds the outer cable shield to the case shall be used, Shields of coaxial cables and shielded balanced transmission lines shall be terminated by peripherally grounding the shield to the equipment case. Coaxial shields and connector shells shall be grounded at junction boxes, patch panels, signal distribution boxes other interconnection points along the signal path.

Shields surrounding a cable containing individually shielded lower frequency signal lines or containing only unshielded lines shall be grounded at each end and at junction boxes, patch panels, distribution points and at other intermediate points along the cable run. Overall shields shall be grounded to cases, cabinets or conducting surfaces... MIL-STD-188-124

Pin Filtered Connectors should be used to protect the chassis signals from incoming noise. Signal Feed-Through Methods

Metal dust caps can be placed on unused external connectors to shield their pins and provide EMI protection [Connector Dust Cap manufacturers].

EMI Gaskets placed around all the connector cut-outs will reduce EMI. This links provides manufacturers of Conductive Elastomer Plastic Gaskets, Beryllium Copper BeCu Metal Gaskets and a number of EMI shielding methods.

Connectors used on the outside panels of the chassis are called panel mount type connectors, or bulk head type connectors. Any style of connector can be made into a bulk head connectors.

Connector Styles; Connectors used in multiple electric circuits should be selected to preclude mis-mating. Where design considerations require plug and receptacles of similar configuration in close proximity, the mating plugs and receptacles should be suitably coded or marked to clearly indicate the mating connectors. In addition to color coding many styles of connectors may be keyed, so that only similar keyed connectors will mate together.

Normally chassis mount connectors are the female type to protect the pins from being shorted to each other. However if two identical connectors are required than one may be male while the other female so that the cables are not mis-connected.

Various MIL5015 Connectors
MIL-5015 Connectors

Connector Contacts; Unused connector contacts or contact positions for external circuits should be provided for future use, and should be located on the periphery (outer contacts) of the connector [provide 2 spare positions for 4 to 25 contacts, or 4 spare contacts for 26 to 100 contacts]. Additional [spare] connectors should not be used in the design.

Connector Selection may also need to account for environmental issues.

Connector Vendors;
Connector Manufacturers {All types}
Military Connector Manufacturers {Metal, EMI}
D-Sub Connector Manufacturers {D Type}
Coax Connector Manufacturers, Operational Frequency Range
Telcom Connector Manufacturers {RJ style}
Industrial Ethernet Connector Manufacturers {Dust, Water Protection}

Connector Dust Caps, next page

Connector Environmental Protection Ratings
Connector Derating Guide Lines
How To Specify a Equipment Chassis; Section Index page

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