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BIRNS Millennium Underwater Interconnect Products

The BIRNS Millennium™ underwater interconnect series is a configurable high performance dry-mate subsea interconnect range designed for deep submergence applications to 6km depth. Available with titanium or stainless-steel connectors and solid (molded) or oil-filled cable in straight or 90° configurations, it offers high and low voltage, RF, fiber optic, and electro-coax, electro-optical and electro-opto-coaxial hybrids.

BIRNS Millennium underwater connector and cable assemblies provide quantifiably superior performance characteristics:
BIRNS’ subsea interconnect products provide faster data transfer rates and greater signal bandwidth, lower optical insertion loss, greater depth capability, lower RF loss and better VSWR. This has been achieved through meticulous and innovative engineering and rigorous testing and a range of industry-leading design features, resulting in powerful, robust field-proven subsea interconnect solutions with the highest performance on the market.

Millennium Deepsea Connector Performance Specifications

BIRNS Millennium



BIRNS Millennium electrical subsea interconnect products are ideal for high performance subsea systems requiring power and fast data transfer, with available high-voltage (≤ 3.6 kV) and/or low-voltage (≤ 600V) contacts.  BIRNS underwater connectors provide excellent contact engagement per MIL-STD-39029D, with insulated solder pots to minimize EMI, noise and cross-talk. Sockets are heat-treated BeCu for longevity and superior electrical contact, and all contacts have 50μ of hard gold plating for superior data transmission.

When multiple conductors are in proximity, each heats the others and decreases availability for cooling, so conductors’ allowed current should be derated when conductors are bundled in a grouping or cable. NFPA 70 (NEC) Tables B.310 define ampacity bundling-derating guidelines and ambient temperature adjustments.

BIRNS ampacity values are merely informational. The system’s electrical designers are responsible to perform detailed engineering analyses of the many factors affecting ampacity.


Actual measurements of AWG sizes can vary from manufacturer to manufacturer. BIRNS conductors are larger than standard AWG sizes to provide additional safety and flexibility.

BIRNS Millennium



BIRNS Millennium underwater connectors and related subsea interconnect products are ruggedly built of corrosion-resistant materials, with 316 stainless steel and Titanium Grade 5 both standard. To prevent Titanium galling, BIRNS titanium coupling rings are anodized per AMS 2487 in a 12.4 pH alkaline bath and then impregnated with PTFE for superb friction reduction and galling resistance.


Note: select items have been tested and qualified to 625 bar open-face and 750 bar mated.



Select EO sizes and configurations have been vibration-tested per MIL-STD-167-1A, Type 1, Table III, to 14 Hz.


Select EO sizes and configurations have been high-impact shock-tested per MIL-S-901D Grade A Class1 Type C. (Grade A items are essential to the ship’s safety and continued combat capability; Class 1 items must pass shock tests without use of resilient mounting.) The tests involve hitting the connector mounting plate in each of three axes (top, side, back) with a 400-lb (182kg) hammer dropped from 1, 3 and 5 feet (.3m, 1m, and 1.5m). The graph (to the right)  shows a typical 5-foot (1.5m) drop test result.

1. Per ASTM G40: “Galling is a form of surface damage arising between sliding solids, distinguished by microscopic, usually localized, roughening and creation of protrusions (e.g.: lumps) above the original surface:.

BIRNS Millennium



BIRNS has developed exclusive deep submergence cable constructed for Cat 8.2 use, and now offers subsea cable assemblies with data transfer rates of 9.4+/- 0.1 Gb/s. Performance testing proved that data consistently transmitted at this rate through the BIRNS 3M-16 over the entire range of pressures from 0 to 8700 PSI (600 bar). Several sizes and configurations are available with data transfer rates of up to 9.4+/- 0.1 Gb/s at 6000m: 3G-10 (Ethernet); 3M-13, 3M-16 and 3O-17 (Ethernet and Power).

Subsequent testing has shown consistent 9.48 Gb/s data transfer even over 20m (65 feet) of cable with five 3M-16 inline mating pairs.

BIRNS Millennium



BIRNS Millennium optical and EO subsea connector configurations deliver the ultimate in high-performance data transmission, with designs qualified in cold-water high-pressure testing and proven in service. Configurations are available for both SM and MM fibers, as well as hybridized with electrical conductors for power and/or control.


SM: .5dB max [typical: .1dB]
MM: 1dB max [typical: .25dB]


35 dB min

The popular 3F-1F-FR (L) and
mating 3F-1F-CP (R).

BIRNS makes ceramic zirconia ferrules in 2.5mm and 1.25mm styles.

A 1.25mm ferrule in a hybridized high-density electro-opto-RF configuration.

BIRNS Millennium


BIRNS produces high-performance RF subsea connectors for 50Ω and 75Ω applications.

BIRNS Millennium pressure-rated, low-loss RF (coax) subsea connectors are ideal for GPS-frequency systems up to SHF (centimetre wave) in IEEE bands S and C, and can be hybridized with electrical contacts and/or optical ferrules. BIRNS 1C and 1V assemblies offer low insertion loss even up to GPS frequencies, while BIRNS 1B units are capable of 18HGz and beyond.

BIRNS Millennium RF subsea connectors are the most advanced and best-performing underwater connectors on the market, with proprietary new RF technology providing low insertion loss, high frequency capability, open face pressure resistance, and 50Ω and 75Ω configurations. BIRNS exclusive RF 1C contacts withstand open face pressure to depths of 6,000m.

The BIRNS “1V” series features a compact 75Ω RF contact in a 50Ω footprint. The new 1V is ideal for HD/SD video with signal frequencies to 3GHz, for shortwave antennas, or for low-power RF needing minimal signal attenuation. And, due to its extraordinarily compact size, the 1V fits into many BIRNS coax pin configurations. BIRNS 1C (50Ω) and 1V (75Ω) contacts can be combined in the same connector, offering a range of flexible, powerful new options in a small space.

BIRNS also offers ultra-low-loss RF “1B” pressure-rated connectors for use to SHF band Ku (18GHz), developed and supplied exclusively for US military applications. BIRNS 1B connectors are qualified for US Navy applications and have undergone additional US Navy saltwater performance qualification testing under conditions of cold (27°F/-3°C) and hot (100°F/38°C) hydrostatic pressure. BIRNS 1B connector solutions provide both strategic and tactical advantages by delivering synchronous, continuous mission-critical data from the submarine to the ship or tactical air cover without need to resurface.

BIRNS RF contacts can be combined and/or hybridized with electrical and/or optical lines. Note the PRO-020 overmolding shown above

Underwater Connector Pin Circuitry Legend

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