Connector Selection Guides

Practical notes from our engineers on choosing, specifying and ordering connectors.

Download all 94 datasheets (PDF) →

38999-type circular connectors

• 38999 Series I, II, III and IV: What Is the Difference?

  How the four 38999 connector series differ in coupling, size, vibration performance and typical use, and how to choose between them for new designs.

• How to Read a 38999 Part Number

  A step-by-step guide to decoding a 38999 Series III part number: connector type, finish, shell size, insert arrangement, contact type and key position.

• D38999 to J599 Part Number Cross-Reference

  How a D38999 Series III part number maps to a J599 configuration: slash type, finish, shell, insert arrangement, contacts and key, with worked examples.

• 38999 Insert Arrangements and Service Ratings Explained

  How 38999 insert arrangements are numbered, what contact sizes they use, and how service ratings M, N, I and II set the withstanding voltage.

Micro-D and Nano-D

• Micro-D vs Nano-D Connectors: How to Choose

  Micro-D (1.27 mm pitch) vs Nano-D (0.635 mm pitch) connectors: differences in current, contact count, mating cycles and variants, and how to choose.

• What Is a Twist-Pin Contact?

  How twist-pin contacts work, why Micro-D and Nano-D connectors use them, and what they mean for contact resistance, vibration resistance and mating life.

Subsea and marine

• Subsea Connector Depth and Pressure Ratings Explained

  How to read underwater connector ratings: operating depth, mated and unmated pressure, how meters convert to MPa, and what to specify for your equipment.

• Wet-Mate vs Dry-Mate Underwater Connectors

  What wet-mateable and dry-mate underwater connectors are, how they differ from connectors mated at depth, and how to specify the right one.

• Rubber-Molded vs Metal-Shell Underwater Connectors

  How rubber-molded and metal-shell underwater connectors differ in depth rating, current and robustness, and which to choose for your equipment.

Sealing and environment

• IP67, IP68 and Hermetic Sealing: What Connector Ratings Mean

  What IP67 and IP68 mean for connectors, how they differ from hermetic sealing and underwater depth ratings, and what to put in your specification.

• Hermetic Connector Leak Rates Explained

  What a hermetic connector leak rate means, how Pa·m³/s converts to mbar·L/s and atm·cc/s, how leak rates are tested and how to specify one.

• Glass-to-Metal vs Epoxy-Sealed Feedthroughs

  How glass-to-metal and epoxy-sealed feedthroughs differ in leak rate, temperature, current and pressure, and which of our series use each seal.

• Connector Shell Finishes and Salt-Spray Ratings

  Nickel, cadmium, nickel-PTFE, stainless, composite and titanium connector finishes compared for salt spray, conductivity, shielding and RoHS.

• Explosion-Proof Connectors: Ex d vs Ex e, Gas Groups and T-Classes

  How to read an Ex marking such as Ex db IIC T6 Gb, flameproof vs increased-safety connectors, and what to specify for hazardous areas.

• Selecting Connectors for High-Temperature Zones

  How insulation, contact and shell materials limit connector temperature, and how to choose between 200 °C, 260 °C, 400 °C and 500 °C connectors.

• Selecting High-Current Power Feedthroughs for Vacuum and Pressure Vessels

  How to choose a high-current power feedthrough: current and stud size, voltage, NPT vs O-ring sealing, leak rate, temperature and testing.

Contacts and electrical

• Choosing Connector Contact Size by Current and Wire Gauge

  How to pick 38999-type contact sizes 22D, 20, 16, 12 and 10 by current and wire gauge, with a reference table and notes on derating and mixed layouts.

• Withstanding Voltage vs Working Voltage in Connectors

  Why a connector's withstanding (test) voltage is not its working voltage, how altitude changes it, and how to choose a safe working voltage.

• EMI Filter Connectors: C vs π Filters and Choosing Capacitance

  How EMI filter connectors work, C vs π filters, how to pick capacitance from cut-off frequency, and precautions for DC filter connectors.

• Thermocouple Connectors and Compensating Contacts

  Why copper contacts add error to thermocouple circuits, how chromel, alumel and compensating-alloy contacts fix it, and how to specify them.

Industrial and rail

• MIL-DTL-5015 Type Connectors for Rail Vehicles

  Why MIL-DTL-5015 type connectors are used on rolling stock: threaded vs reverse-bayonet coupling, service ratings and rail standards.

Rugged computing

• VPX Connectors: VITA 46, VITA 66 and VITA 67 Explained

  An overview of VPX backplane connectors: VITA 46 differential modules, VITA 67 RF and VITA 66 fiber modules, 3U and 6U layouts, and how to specify them.

• Choosing Liquid-Cooling Quick-Disconnect Connectors

  How to choose liquid-cooling quick-disconnect connectors: bore and flow, pressure drop from Kv, working pressure, spillage and seal materials.

Working with us

• How to Identify a Connector from Photos

  Which photos and measurements identify a connector with no part number: coupling, contact layout, keying, mounting and markings.

• From Inquiry to Series Production: Samples and Qualification

  How a custom connector moves from inquiry to series production: configuration, quotation, samples, third-party tests and approval.