Published: July 17, 2026 · Technical Guide
MIL-DTL-38999 is the U.S. Department of Defense specification for high-performance circular connectors used in aerospace, military ground vehicles, naval systems, and other harsh-environment applications. It defines four series (I, II, III, IV), with Series I and III being the most widely deployed in the global defense supply chain.
These connectors are designed for extreme conditions: operating temperatures from -65°C to +200°C, 500+ mating cycles, resistance to shock, vibration, and corrosion. They are manufactured by Amphenol, TE Connectivity, SOURIAU, and a growing number of qualified alternative suppliers — including Airoadcon.
| Feature | Series I | Series III |
|---|---|---|
| Specification | MIL-DTL-38999 Series I | MIL-DTL-38999 Series III |
| Shell Styles | Wall mount, jam nut, straight plug | Same + additional scoop-proof design |
| Scoop-Proof | No — contacts can be damaged by misalignment | Yes — recessed pins prevent damage |
| Coupling | Bayonet (quick-connect, 1/3 turn) | Triple-start threaded (anti-vibration) |
| Contact Density | Standard (up to 128 contacts) | Higher (up to 187 contacts in same shell) |
| Sealing | Interfacial + wire sealing | Improved environmental sealing (IP67+) |
| Vibration Resistance | Good | Excellent — threaded coupling won't loosen |
| Weight | Lighter | Slightly heavier (threaded coupling adds mass) |
| Amphenol PN Prefix | D38999/24, /26 | D38999/20, /24, /26 (with scoop-proof) |
| TE PN Prefix | DTS24, DTS26 | DTS20, DTS24, DTS26 |
| SOURIAU PN Prefix | 8LT7 | 8LT |
| Typical Use | Ground vehicles, avionics bays | Engine nacelles, exterior airframe, naval |
All Airoadcon connectors are form-fit-function compatible with these major brands. Same mounting dimensions, same contact arrangements, same performance specs — manufactured in-house with full MIL-STD QC.
| Standard | Shell Style | Amphenol | TE Connectivity | SOURIAU | Airoadcon |
|---|---|---|---|---|---|
| Series III | Wall Mount Rec. | D38999/20 | DTS20 | 8LT | J599/20 |
| Series III | Jam Nut Rec. | D38999/24 | DTS24 | 8LT7 | J599/24 |
| Series III | Straight Plug | D38999/26 | DTS26 | 8LT | J599/26 |
| Series I | Wall Mount Rec. | D38999/24 | DTS24 | 8LT7 | K/24 |
| Series I | Jam Nut Rec. | D38999/24 | DTS24 | 8LT7 | K/24J |
| Series I | Straight Plug | D38999/26 | DTS26 | 8LT7 | K/26 |
| Series II | Wall Mount Rec. | PT/PC | KPSE/KPT | — | JY/20 |
| Series II | Straight Plug | PT/PC | KPSE/KPT | — | JY/26 |
| 83723 III | Wall Mount | GT/5015 | Matrix 83723 | — | ZH83723/20 |
| GJB 599A I | Jam Nut Rec. | D38999/24 | DTS24 | 8LT7 | GJB599/24 |
Understanding MIL-DTL-38999 part numbers helps you navigate cross-referencing:
| Segment | Example | Meaning |
|---|---|---|
| Spec | D38999 | MIL-DTL-38999 specification |
| Shell Style | /20 | Wall mount receptacle (Series III) |
| Plating | W | Olive drab cadmium (F = electroless nickel) |
| Shell Size | B | Shell size 11 (A=9, B=11, C=13, D=15, E=17, F=19, G=21, H=23, J=25) |
| Insert Arrangement | 35 | 13× #22D contacts (varies by shell size) |
| Contact Type | P | Pin (S = Socket) |
| Polarization | N | Normal (A, B, C, D for alternate keying) |
Airoadcon's J599, K Series, JY Series, and ZH83723 connectors undergo the same MIL-STD testing as their Amphenol/TE/SOURIAU counterparts:
Looking for MIL-DTL-38999 connectors?
We offer J599 Series III connectors that are drop-in replacements for Amphenol, TE, and SOURIAU. Same specs, better pricing, free samples for qualified buyers.
Email: info@airoadcon.com | Phone: +86-189-9192-7716