HF50CXIL6M / HF75CXIL6M | 7-Contact (1 Coax + 6 Electric) Coax Male In-Line | 50Ω & 75Ω | 3.0 GHz | RV POWER

The HF50CXIL6M / HF75CXIL6M are SubConn® HF Coax 7-contact (1 coax + 6 electric) Male In-Line connectors — a cable-mount in-line connector that joins two coaxial cable runs mid-run without requiring a chassis or panel mount. Available in both 50 Ω (HF50CXIL6M) and 75 Ω (HF75CXIL6M) impedance options, they transmit high-frequency RF signals to 3.0 GHz with qualified hydrostatic pressure of 600 Bar (8,700 psi) when mated. Based on the proven SubConn® Circular body geometry, they deliver SubConn®-standard mechanical reliability with gold-plated coaxial contacts and chloroprene rubber construction — rated for 500+ dry mating cycles with contact resistance below 10 mΩ.

1 coaxial contact + 6 electric contacts | 50 Ω or 75 Ω | 3.0 GHz Max | 600 Bar Mated | Dry-Mate Only | SubConn® HF Coax Standard

Key Design Features

• Dual impedance availability — 50 Ω (HF50CXIL6M) for general RF, radar, sonar, and telemetry; 75 Ω (HF75CXIL6M) for video, CATV-standard, and broadcast-format underwater camera systems — same mechanical platform, different coaxial insert geometry
• 3.0 GHz maximum frequency — supports wideband RF transmission including HD video, USBL sonar, acoustic telemetry, and spread-spectrum subsea communication protocols at depths up to 6,000 m
• 800 V coaxial voltage rating (50 Ω) / 600 V (75 Ω) — high-voltage coaxial insert tolerates sonar pulse transients and high-power RF transmit events without dielectric breakdown
• 6 integrated electric contacts — 300 V DC/AC / 5 A per contact (max 20 A) — combines RF coaxial signal and low-voltage control/power in a single connector body, eliminating the need for a separate multi-pin power connector alongside the coax feed
• 600 Bar mated pressure — qualified to 600 Bar / 8,700 psi when mated; based on SubConn® Circular body geometry with DLSA snap ring retention
• Dry-mate design — optimised for deck-side mating before deployment; not designed for open-face pressure or underwater mating operations — locking sleeves are mandatory before deployment
• Gold-plated coaxial contacts — precision-machined centre conductor and outer shield with gold plating; contact resistance < 10 mΩ; insulation resistance > 200 MΩ
• Chloroprene rubber body — chemically resistant to seawater, hydraulic fluid, and biofouling; −4 °C to +60 °C in water, −40 °C to +60 °C in air
• Multi-material bulkhead body — brass, 316L stainless steel, titanium, or anodised aluminium — material-matched to any hull or chassis specification

Electrical & Mechanical Specifications

Typical Applications

• Underwater HD video systems — 75 Ω (HF75CXIL6M) for NTSC/PAL/HD-SDI video signal transmission from subsea cameras to surface display and recording systems; 50 Ω (HF50CXIL6M) for digital video over RF modulated links
• USBL and sonar transponders — 50 Ω (HF50CXIL6M) for ultra-short baseline acoustic positioning system transducer cables, sub-bottom profiler transducers, and multibeam sonar head connections
• ROV telemetry systems — wideband RF links for spread-spectrum acoustic telemetry modems, subsea WiFi, and acoustic communication systems in ROV and AUV platforms
• Underwater antenna systems — 50 Ω RF feed connections for subsea antenna arrays, hydrophone arrays, and acoustic Doppler current profilers (ADCP)
• Combined RF + power/control — single 7-contact (1 coax + 6 electric) connector delivers coaxial RF signal simultaneously with six low-voltage control circuits (300 V / 5 A per contact), eliminating separate connector pairs on ROV camera pods and sonar heads
• Oceanographic instrument moorings — high-frequency sensor signal connections in self-recording mooring instruments, ADCP profilers, and acoustic release systems
• Naval and defence systems — sonar array feed connections, underwater antenna systems, and acoustic countermeasure electronics in naval underwater platforms
• Marine renewable energy — acoustic monitoring and SCADA communication connections in tidal energy arrays and offshore wind installation survey systems
• Underwater inspection systems — video and control signal connections for pipeline inspection ROVs, hull inspection vehicles, and remote inspection crawlers

Why Choose the HF50CXIL6M / HF75CXIL6M

1. 50 Ω and 75 Ω on the Same Platform — One Mechanical Standard

The HF50CXIL6M (50 Ω) and HF75CXIL6M (75 Ω) share an identical mechanical platform — same body dimensions, snap ring geometry, O-ring sealing, and cable entry — with only the coaxial insert differing. This allows system designers to use the same connector tooling, field repair kits, and locking sleeves across both impedance standards, reducing the spare parts burden on vessel operations. Choose 50 Ω for sonar, telemetry, and radar; 75 Ω for video, CATV-compatible, and broadcast-format subsea camera systems.

2. 3.0 GHz — Wideband RF to Full-Ocean Depth

Rated to 3.0 GHz maximum frequency — sufficient for HD video (up to ~2 GHz modulated), USBL positioning (10–100 kHz acoustic carrier through wideband electronics), spread-spectrum communication modems (up to 500 MHz), and S-band sonar systems. The 600 Bar / 8,700 psi mated qualification exceeds the pressure at 6,000 m depth by a factor of 1.5×, making the HF50CXIL6M/HF75CXIL6M suitable for any operational ROV depth class.

3. Dry-Mate — Zero Impedance Discontinuity from Water Ingress

The SubConn® HF Coax series is designed for dry mating only — topside before deployment. This design choice preserves the precision impedance geometry of the coaxial insert: water in the coaxial cavity causes significant impedance discontinuity and reflection (VSWR spike) that degrades high-frequency signal integrity. Proper deck-side mating with locking sleeve engagement before deployment ensures a dry, controlled-impedance connection throughout the dive.

4. SubConn® Circular Body — 600 Bar Proven Reliability

The HF50CXIL6M/HF75CXIL6M are built on the SubConn® Circular body platform — the same chloroprene rubber body, DLSA snap ring retention, and nitrile O-ring sealing used across thousands of deployed SubConn® Circular connectors in ROV, observatory, and offshore systems worldwide. The coaxial-specific body has been independently qualified to 600 Bar / 8,700 psi mated, with pressure test certification available on request.

5. Combined RF + 6-Circuit Power/Control — System Simplification

The HF50CXIL6M / HF75CXIL6M integrate a single coaxial RF channel with six electric contacts rated at 300 V / 5 A per contact (max 20 A) in one compact SubConn® body. This replaces the otherwise-required connector pair (one coax + one multi-pin) on camera pods, sonar heads, and instrument nodes — reducing penetration count through pressure housing walls, simplifying cabling, and eliminating the risk of connection error between adjacent coax and power connectors.

SubConn® HF Coax — Male In-Line Family

How to Select: 50 Ω vs 75 Ω

Frequently Asked Questions — HF50CXIL6M / HF75CXIL6M

Q: What is the maximum frequency of the HF50CXIL6M and HF75CXIL6M?
A: Both the HF50CXIL6M (50 Ω) and HF75CXIL6M (75 Ω) are rated to a recommended maximum frequency of 3.0 GHz. At 3.0 GHz, attenuation is 22.5 dB/10 m (50 Ω) or 15.7 dB/10 m (75 Ω) — both measured on a 10 m cable assembly including 2 bulkhead connectors.

Q: What is the depth rating of these coax connectors?
A: Qualified to 600 Bar / 8,700 psi when mated — equivalent to approximately 6,000 m ocean depth. Note: the SubConn® HF Coax series is dry-mate only and not designed for open-face pressure or wet mating. Locking sleeves must be engaged before deployment.

Q: Why is the coax series dry-mate only?
A: Water in the coaxial cavity introduces significant impedance discontinuity, causing reflections and high VSWR that severely degrade high-frequency signal integrity. The HF Coax series is designed for topside mating before deployment to maintain the precision controlled-impedance geometry of the coaxial insert throughout the dive.

Q: What is the difference between the HF50CXIL6M/HF75CXIL6M and the coax-only variants (HF50CXBHF/HF75CXBHF)?
A: The HF50CXIL6M/HF75CXIL6M add 6 electric contacts (300 V / 5 A per contact, max 20 A) alongside the coaxial RF channel — combining RF signal and power/control in a single connector. The coax-only variants (HF50CXBHF/M, HF75CXBHF/M) carry only the coaxial signal, suited to applications where power is routed separately.

Q: When should I choose 50 Ω vs 75 Ω?
A: Choose 50 Ω (HF50CXIL6M) for sonar transducers, USBL systems, acoustic modems, radar, and most RF electronics that use 50 Ω as their system impedance standard. Choose 75 Ω (HF75CXIL6M) for underwater video cameras (CVBS, HD-SDI, analogue), CATV-compatible systems, and broadcast-format signal chains where 75 Ω is the standard impedance throughout.

Q: What coaxial cable is used with these connectors?
A: The HF50CXIL6M inline cable uses PUR jacket with RG58 coax; bulkhead lead uses RG316 coax. The HF75CXIL6M inline cable uses PUR jacket with Mini-RG59 coax; bulkhead lead uses RG179 coax. BNC termination connectors: 50 Ω → Amphenol 031-315-RFX or 112116; 75 Ω → Amphenol 112133 or Belden 1855ABHD3.

Q: What is the difference between HF50CXIL6M/HF75CXIL6M (In-Line) and the Bulkhead variants HF50CXBH6M/HF75CXBH6M?
A: The HF50CXIL6M/HF75CXIL6M (In-Line) terminate a free cable mid-run without requiring a panel or chassis mount. The HF50CXBH6M/HF75CXBH6M (Bulkhead) mount through an instrument panel and create a fixed feedthrough point. Most systems use a Bulkhead/In-Line mated pair.

Q: Must locking sleeves be used?
A: Yes — locking sleeves are mandatory before deployment. The SubConn® HF Coax series relies on locking sleeve engagement to maintain the mating preload that ensures watertight sealing at depth. Avoid greasing the coaxial contact portion — dielectric grease on the coaxial insert degrades RF signal integrity.

Q: Is pressure test certification available?
A: Yes. RV POWER GROUP provides certified hydrostatic pressure testing to specific ocean depths on request, with full test certificates and material traceability documentation. Contact [email protected].

Installation, Mating & Maintenance Guidelines

Pre-Mating Inspection

• Inspect the coaxial centre conductor and outer shield before every mating — bent or contaminated coaxial contacts cause VSWR degradation that is not detectable visually after mating
• Verify O-rings on the outer body are intact and clean — salt crystal deposits prevent full O-ring seating and allow water ingress at depth
• Apply dielectric grease to the outer body O-ring sealing surfaces only — do NOT apply grease to the coaxial insert itself, as this degrades RF contact integrity
• Ensure the locking sleeve is present and in good condition — the HF Coax series cannot be safely deployed without the locking sleeve engaged

Mating Procedure (Dry-Mate Topside)

• Mate connectors on deck before deployment — the HF Coax series is not designed for underwater mating
• Align the DLSA snap ring geometry before applying axial load; engage the snap ring with steady pressure until a positive click is felt
• Engage and tighten the locking sleeve fully — verify the sleeve is flush and cannot be disengaged without tool assistance
• Perform a continuity check and VSWR/return loss measurement at the system level before deployment to confirm coaxial contact integrity

Post-Recovery Maintenance

• Flush the connector body (not the coaxial insert) with fresh water immediately after recovery
• Allow the coaxial contact area to air-dry completely before storage — moisture trapped in the coaxial cavity can cause galvanic corrosion on the gold-plated centre conductor over time
• Inspect the locking sleeve threads or snap engagement after every 50 mating cycles
• Replace O-rings at 200-cycle intervals or if any cracking, deformation, or compression set is observed

For technical datasheets, pressure test certificates, custom cable assemblies (RG58, RG316, Mini-RG59, RG179), or volume pricing, contact RV POWER GROUP at [email protected]. OEM supply and consignment stock programmes available for qualified system integrators.

• Coax_series_of_underwaterconn_com.pdf