Introduction: The MCIL3F cable plug and MCBH3M bulkhead receptacle form a 3 pin micro circular underwater connector set, and the selection starts with the moving cable side, the fixed housing feedthrough, and the pin functions that must pass between them.
A 3 pin micro circular underwater connector works only when the cable plug, the bulkhead receptacle, and the housing feedthrough agree on the same interface. In most ROV sensor pods, that interface question appears long before anyone opens a catalog. A sensor sits inside a pressure housing, its harness leaves through a flange, and the joint must survive years of seawater at depth. The MCIL3F cable plug and MCBH3M bulkhead receptacle are the two halves of that answer, and they do different jobs. Determine which end travels with the cable, how many contacts the signal set needs, and what the housing flange can accept; the rest of the selection follows.
The set is split by function. MCIL3F is the female cable plug: it terminates the sensor harness, moves with the cable, and takes the handling during mating. MCBH3M is the male bulkhead receptacle: it is fixed into the housing wall, its rear wiring stays protected inside the pod, and it remains in place for the life of the instrument. A threaded coupling with a POM locking sleeve pulls the two halves together. The mated joint carries IP69 protection and a nominal 7000 m / 70 MPa working depth across a -50 to +100°C range. Each shell and contact set is built for one role, so a plug cannot be mounted on a bulkhead flange. The layout has to start from which side moves.
On the cable side, MCIL3F turns routing decisions into interface decisions. The plug carries solder-terminated contacts inside a 316L stainless steel shell with a chloroprene rubber insert. The harness needs enough slack to form a service loop, strain relief so the solder joints never carry tension, and a jacket that suits the cable entry. A polyether jacket with aluminium foil shielding is the usual choice for seabed work. Run the cable route in the mechanical model first, then confirm the plug body clears structural members and handholds through its full mating and unmating travel. Reaching that conclusion after the harness is potted is an expensive way to learn it.
On the housing side, MCBH3M has to agree with metal that already exists. The bulkhead side comes in a threaded-hole mount and a through-hole locknut mount. The through-hole version expects an 11.2-11.4 mm bore with a sealing face no larger than 25 mm across and a finish of Ra1.6 or better. Wall thickness, internal clearance for the rear wiring, and tool access for the locknut all decide whether a receptacle belongs on that flange. The 316L shell handles seawater exposure and the chloroprene insert carries the seal, but the flange geometry pins down the exact part number.
The 3 pin version covers a common ROV sensor pattern: a positive supply, a return, and one signal line or shield reference. Counting functions is the fastest way to test whether 3 pins are enough. A sensor that also needs a differential pair, a trigger line, or a separate excitation voltage has outgrown it. The micro circular series supports 2-21 pin configurations within the same connector family, so the interface concept stays the same while the shell grows to carry more contacts. Adding spare pins at the drawing stage is simpler than adding them after the harness is built. Cable entry is the other half of that decision. Solder termination means the harness maker needs a defined pin assignment, a wire gauge that fits the solder cups, and a jacket diameter matched to the cable entry hardware. A thick polyether jacket with foil shielding that will not fit the back of the plug is a design conflict, not a sourcing problem, so settle it early. Specify finished cable length, jacket outside diameter, and shield termination method along with the pinout, because the plug is built as part of the harness rather than added afterward. Mating life also deserves a quick look: gold-plated brass contacts specified for more than 500 mating cycles are generous for a sensor connected once per deployment and tight for a test port cycled weekly.
A drawing review moves fast when the submission answers mechanical and electrical questions at the same time. On the mechanical side, send the mount style (threaded hole or through-hole locknut), the bore diameter for the locknut version, the sealing face diameter and finish of Ra1.6 or better, the wall thickness, and the clearance behind the flange for rear wiring. On the electrical side, send the pin count, the function assigned to each pin, the wire gauge and jacket outside diameter of the harness, and whether the shield ties to a dedicated contact or to the shell. Add working depth and temperature range so the review can confirm the standard envelope in one pass. Depth and temperature belong in the same conversation. The set is specified for nominal 7000 m / 70 MPa and -50 to +100°C, which covers deep sensor pods and cold deck conditions alike. If your pod runs hotter or deeper, say so before the drawing is released rather than after. Fit depends on aligned mechanical dimensions and electrical definitions, so attach the existing connector drawing or a measured flange sketch whenever you are matching an interface already in the field. That package gives an underwater connector manufacturer the facts needed to provide a defined part number, a cable assembly definition, and a sample route in one exchange.
ROV sensor wiring comes down to three things that are easy to keep separate: which half moves with the cable, how many contacts the signal set truly needs, and what the housing flange will accept. Once those are settled, the MCIL3F female cable plug and MCBH3M male bulkhead receptacle form a clean, well-defined pair. Send the flange drawing, the pin list, and the working depth together, and ask for the matching mount style, pin count, and cable length in the same inquiry so your harness design is not built around a guess. For a repeatable sensor platform, a micro electrical underwater connector manufacturer can review the same package and define the cable assembly around the flange. For wholesale underwater connector projects, keep that locked interface definition; an underwater electrical connector supplier can use it to maintain consistent part definitions across builds.
A: The MCIL3F is the female cable plug. It is solder-terminated to the sensor harness and moves with the cable during mating and handling. The MCBH3M is the male bulkhead receptacle. It mounts into the housing wall through either a threaded hole or a through-hole locknut, and its rear wiring stays protected inside the pod. One end travels; the other stays fixed. Order and document them as a mating pair.
A: Count the functions your sensor needs first: supply, return, signal, and any shield reference. If that fits into three contacts, check the harness jacket diameter against the cable entry. Then confirm the housing bore at 11.2-11.4 mm for the locknut mount with a Ra1.6 sealing face. Matching depth, temperature, and pin definitions completes the check.
A: Send mount style, bore diameter, sealing face diameter and finish, wall thickness, and rear clearance. Include pin count with each pin's function, wire gauge, jacket outside diameter, finished cable length, and shield termination. Add working depth, temperature range, and any existing connector drawing you are matching, so the review returns a part number and cable assembly definition.
Science & Technology for Exploration - NOAA Ocean Exploration
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