Articles

New Stacking Connector Technology Simplifies Logistics

The proliferation of scalable tactical equipment has driven the need for field configurable power-distribution systems. A stacking-interconnect technology has been developed that utilizes the same mating interfaces and locking mechanisms as standard MILDTL- 55181 connectors without the logistics planning and storage space requirements of Y-cables and power distribution panels.

Stacking connector mated to a power source and a “piggybacked” QPL connector sharing power.
The scope section of the MIL-DTL- 55181 detail specification defines “…a series of center-lock coupling screw, waterproof, polarized, multi-contact, intermediate power connectors for interconnection of power and control circuits on electronic equipment” for use by all departments and agencies of the Department of Defense.

This specification defines three insert arrangements that provide configurations with four 12-AWG contacts, nine 20- AWG contacts, or eighteen 20-AWG contacts. The 12-AWG contacts are rated at 35 amps and are used to provide power connections. The 20-AWG contacts are rated at 7.5 amps and have been used to facilitate power or data connections.

Five different cable sizes are defined ranging from .343 to .593 inches in diameter. Since the initial specification, increased data rates have necessitated the use of shielded cables and consequent inclusion of connector requirements to handle the shielded cables.

MIL-DTL-55181 connectors have been deployed in over one-half-million SINCGARS (Single Channel Ground and Airborne Radio System) radios. Subsequent adoption of these connectors has included a wide range of software- defined-radio platforms that have included the JTRS (Joint Tactical Radio System). These rugged and versatile connectors have also been used in power supplies, surge suppression systems, and power amplifiers.

The function of the stacking connector receptacle- mating pins and coupling screw is the same as QPL connectors.
Distributing power for tactical equipment has been facilitated by Y-cables but this scalability did not come without complications. Logistics planning was required to assure that the correct quantity of cables, additional routing and securing needed to ensure that the Y cables did not get in the way when in use, and dedicated pre and post deployment storage space were available. In addition, the length of the cable, and location of the “Y” splice, can vary from application to application and precluded standardizing cable management.

Recognizing the inherent complications of using “Y” cables, a defenseindustry prime contractor issued an RFQ in support of a U.S. Army program that incorporated two SINCGARS radios that would be powered from a common receptacle. The prime contractor specified a new technical challenge in the RFQ; the power sharing would be accomplished “with no extra parts needed and no parts left over”. This stipulation precluded the use of “Y” cables and power distribution panels.