MIL-DTL-38999
Miniature circular connectors in four series, with bayonet, threaded or breech coupling. M85049 accessories included.
Guide: MIL-DTL-38999 part numbers
Emech Workbench
MIL-SPEC connector part numbers and accessory selection
Build or decode connector part numbers from compiled specification data, then find compatible contacts, mating connectors, backshells and other accessories for high-reliability aerospace and military harnesses—all without digging through multiple data sheets.
See it in action
A short, narrated walk through the MIL-DTL-38999 Series III builder: build a part number, check its contacts and mates, add a backshell, collect a parts list, share a link and decode a part number.
What the video shows
- Pick the shell style from pictures: a /26 straight plug.
- Pick the class. Each list offers only the options the specification allows with your earlier picks.
- Pick the insert arrangement from its contact layout. The shell size fills in.
- Pick the contact style and polarization. The key layout shows, and the part number D38999/26WD35PN is complete, with what each code means.
- See the contacts and the mating connectors. Filters narrow the mates by plating and contact durability.
- Add an accessory that fits the connector: an M85049/38 strain relief.
- Tick “Add to parts list” for the connector, its contacts and the strain relief, then copy the list or download it as CSV. Copy link saves the whole setup.
- Decode a part number you already have: D38999/24WJ35PN.
Connector families
Pick a family, then a series, to open its part number builder.
MIL-DTL-26482
Bayonet-coupling circular connectors with crimp contacts. Series 2 environment-resisting sheets and hermetic class N.
- Series 1 · coming soon
- Series 2
MIL-DTL-83723
Circular connectors with threaded or bayonet coupling and crimp contacts. Series III is active for new design.
MIL-DTL-5015
Circular threaded AN-type connectors with solder and crimp contacts.
MIL-DTL-24308 (D-sub)
Rectangular D-subminiature connectors in six shell sizes. Solder and crimp contacts, nonmagnetic and hermetic, with backshells, screw locks and crimp contacts.
Coming soon: MIL-DTL-83513 (micro-D), MIL-DTL-28840.
Guides
How to read a part number, find a mating connector and choose accessories. Each guide links to the builders it is about, and says what they cover and where they stop.
MIL-DTL-38999 part numbers
How to build or decode a Series I-IV part number, with the Series III fields, codes and a worked example.
Read guide Series I and II breakdownThe shared Series I and II field order: MS number, class, shell size, finish, insert arrangement, contact style and polarization.
Read guide Series IV breakdownReading a Series IV part number: slash sheet, class, shell-size code, insert arrangement, contact style and polarization.
Read guide MIL-DTL-26482 Series 2 part numbersWhat the Series 2 builder covers, how its part-number fields work, and which sheets it leaves out.
Read guide Finding a mating connectorHow the builder lists candidate mates, what its filters mean, and what you must still verify.
Read guide M85049 accessoriesWhat M85049 backshells, strain reliefs, boots, bands, dummy contacts and seal plugs are for, and a step-by-step way to choose one.
Read guide What is a QPL?Why a part number the spec allows can still have no qualified source, and what the builder's "No QPL" warning means.
Read guideEngineering notes
Dated articles on designing with these connectors: why a detail of the specification matters in a harness or a panel, with original illustrations and the spec paragraphs behind every value.
Wire splices and circular mil area
Five kinds of splice with their pluses and minuses, and how to add up circular mil area when several wires share one barrel.
· Read note Backshell clocking and anti-rotation teethWhy an elbow backshell only points in fixed steps, how the key position shifts those steps, and why the same teeth carry the ground path.
· Read noteWelcome
EMech WorkBench is for the people who design electrical and electromechanical hardware for aerospace, military and defense, space, and every other application where high reliability is a requirement, not a goal.
There is no degree in this work. Designers learn it on the job: from specifications and standards, from the colleagues who came before them, and from the school of hard knocks. Much of that knowledge is spread across long documents, old drawings and experience that is hard to pass on.
This site brings some of that knowledge together into practical tools. The goal is simple: help experienced designers work faster, and help people new to the field get past the learning curve sooner.
How the tools are built
Built on the specifications
The tools work from published specifications and standards, and say where their data comes from.
Made for real design work
Each tool answers the questions that come up at the bench: which part, what mates with it, what goes with it and what fits.
Private by design
There is no account and no sign-in. Your selections go to the site’s server only to build the result, and aren’t stored or linked to you.
Always growing
Tools are added and improved over time, and feedback from designers shapes what comes next.
Tools
Connector part number tools
AvailableBuild and decode MIL-SPEC circular connector part numbers one field at a time, and see the contacts, mating connectors and accessories that go with each connector.
What you can do
- Build a part number field by field. Each list offers only the options the specification allows with your earlier choices.
- Decode a part number you already have, to see what each part of it means.
- See the insert arrangement for the connector you picked and, for most series, its key and keyway positions.
- List the contacts, with quantities and standard contact part numbers.
- Find mating connectors, filtered by plating and contact durability.
- Add accessories that fit the connector: M85049 backshells and, for Series III and IV, shrink boots, shield bands and seal plugs.
- Keep a parts list as you work. Copy it into a spreadsheet, download it as CSV, or search Newark for any part number.
- Share a link. The page address holds the whole configuration, so you can bookmark it or send it to a colleague.
How it works
- Choose a connector series.
- Pick the options — shell style, shell size, insert arrangement and so on — or paste a part number to decode it.
- Add the parts to your list, then copy or download it, or copy the link to come back to it later.
More tools on the way
PlannedThe connector tools are the first of many. More tools for electromechanical design are planned. If there is a tool you wish you had, tell us with the Feedback button.
Before you use a result
These are reference tools. Their results are built from published specifications and secondary sources, and specifications are revised over time. Check every part number, value and quantity against the current specification and your own design requirements before you buy, build or release anything. See Part numbers and purchases.
This site isn’t affiliated with or endorsed by the U.S. Department of Defense, SAE International or any manufacturer.