J599 Series III Circular Connectors (38999 Series III Type)
38999 Series III type · shell sizes 9–25 · 184 insert arrangements
38999-Type Circular Connectors
38999-type circular connectors in all four coupling styles — bayonet (Series I), low-profile bayonet (Series II), threaded (Series III) and quarter-turn (Series IV) — plus hermetic, double-flange PCB and IP67 waterproof versions.
38999-type connectors are the standard choice when a circular connector must be small, sealed, shielded and reliable under vibration. The four series share the same style of insert arrangements but differ in how they couple: Series I and II use a bayonet, Series III a triple-start thread that locks itself, and Series IV a 90° quarter turn.
Our connectors are built to the Chinese GJB 599 specifications, the counterparts of MIL-DTL-38999. They are used in rail, energy, industrial automation, test and marine equipment, and are available as plugs, square-flange, jam-nut and hermetic receptacles, double-flange PCB receptacles and IP67 waterproof versions.
Compare series
| Series | Coupling | Shell sizes | Insert arrangements | Contact sizes | Temperature | Mating cycles |
|---|---|---|---|---|---|---|
| J599 Series III | Triple-start thread | 9 to 25 | 184 | 26 to 10 (2–33 A) | −65 to +200 °C | 500 (1500 option) |
| J599WR | Triple-start thread | 9 to 25 | 105 | 22D to 10 (5–33 A) | −65 to +175 °C | 500, 1500 or 5000 |
| GJB599 Series I | Bayonet | 9 to 25 | 127 | 22D to 10 (5–33 A) | −65 to +200 °C | 500 |
| GJB599 Series II | Bayonet, low profile | 8 to 24 | 96 | 22D to 12 (5–23 A) | −65 to +200 °C | 500 |
| J599HR | Triple-start thread, double-locking | 9 to 25 | — | — | −65 to +200 °C | 1000 |
| J599G | Triple-start thread, anti-decoupling | 9 to 25 | — | 26 to 10 (2–33 A) | −65 to +200 °C | 500 |
| GJB599 Series IV | Quarter-turn (90°) | 11 to 25 | 123 | 22D to 10 (5–33 A) | −65 to +200 °C | — |
| Double-flange PCB receptacles | Bayonet (Series I) or threaded (Series III) | 9 to 25 | 50 PCB layouts | 22D to 16 (5–13 A) | −65 to +200 °C | — |
| J599FS | Triple-start thread | 9 to 25 | 32 | 22D to 12 (5–23 A) | −65 to +200 °C | — |
| J599 III differential | Triple-start thread | — | — | — | −65 to +200 °C | — |
J599WR Marine-Grade 38999 Circular Connectors, Cadmium-Free
Cadmium-free nickel-PTFE finish · marine-grade · up to 5000 mating cycles
GJB599 Series I Bayonet Circular Connectors (38999 Series I Type)
38999 Series I type · bayonet coupling · 127 insert arrangements
GJB599 Series II Low-Profile Bayonet Connectors (38999 Series II Type)
38999 Series II type · low-profile bayonet · 96 insert arrangements
J599HR High-Vibration 38999 Series III-Type Plugs
400 g shock · 1.5 g²/Hz random vibration · 1000 mating cycles
J599G 38999 Series III-Type Connectors with Audible Full-Mate Indication
Full-mate indication by feel and sound · shell sizes 9–25 · hermetic versions
GJB599 Series IV Quarter-Turn Circular Connectors (38999 Series IV Type)
38999 Series IV type · 90° quarter-turn coupling · shell sizes 11–25
38999-Type Double-Flange PCB Receptacles
Panel flange + PCB flange · 17 mm spacing · 50 PCB layouts
J599FS IP67 Waterproof 38999-Type Connectors with J1784FS Backshells
IP67 with J1784FS backshell · threaded 38999 type · rain-tested
38999 Series III-Type Differential Connectors, 1.65 Gbps
Size 8 differential · 1.65 Gbps · marine grade
How to choose
Replacing a D38999 part
Send us your D38999 or manufacturer part number. We match shell size, insert arrangement, contacts, finish and key position, and can supply samples for your mating test.
Coupling style
Threaded Series III for the heaviest vibration; bayonet Series I for fast mating; low-profile Series II where space and weight are tight; quarter-turn Series IV for fast, positive locking.
Shell size and insert arrangement
Choose the smallest shell that carries your circuits. Each series page lists all insert arrangements with contact sizes and service ratings.
Shell material and finish
Aluminum for general use, composite for up to 2000 h salt spray and low weight, stainless steel or titanium for strength and hermetic sealing.
Contact size and current
Contacts from size 26 (2 A) to size 10 (33 A); coax, shielded and twinax contacts in selected layouts.
Temperature and sealing
Standard versions run from −65 to +200 °C; MT versions reach 260 °C. Fluorosilicone seals are available for oil exposure.
Options beyond the standard connector
IP67 waterproof
J599FS with J1784FS waterproof backshells.
Double-flange PCB receptacles
Panel flange and board flange, 17 mm apart.
Lightweight miniature version
J599S5: same insert arrangements, 30–41 % lighter.
Hermetic receptacles
Glass-sealed receptacles with leak rate ≤ 1 × 10⁻⁸ Pa·m³/s, in Series I to IV.
High-temperature 260 °C
MT versions in stainless steel for hot zones near engines and process equipment.
Composite and titanium shells
Up to 2000 h salt spray (composite) or highest strength-to-weight (titanium).
Cable assemblies
Connectors terminated to your cable and backshell.
Frequently asked questions
Can you replace my D38999 connectors?
Our connectors are built to GJB 599 Series I to IV, the Chinese counterparts of MIL-DTL-38999 Series I to IV. Send us your part number and we will propose the matching configuration and samples for your own mating test.
Which 38999 series do I need?
Match the coupling of the mating part: bayonet (Series I), low-profile bayonet (Series II), threaded (Series III) or quarter-turn (Series IV). If you are designing new equipment, Series III is the most common choice for vibration.
Which shell sizes are available?
Series I, III and IV use shell sizes 9 to 25 (Series III and IV codes A to J; Series IV starts at 11). Series II uses sizes 8 to 24.
Are these connectors RoHS compliant?
Olive-drab cadmium finishes are not RoHS compliant. If you need RoHS compliance, choose a nickel, composite, stainless-steel or titanium version and state RoHS in your inquiry; we will confirm compliance with the quotation.
What is the lead time?
It depends on configuration and quantity. Send us the part number and quantity, and we will confirm the lead time with the quotation.
From sample to production
Send your requirement
Part number, drawing, pin-out or a short description of your application.
Configuration and quote
Our engineers match the configuration and reply with a drawing and quotation.
Samples
Samples are made to your order. Third-party testing to your specification is available on request.
Your approval
You test the samples in your own equipment and approve them.
Series production
Production follows the approved sample configuration.
Need a quote or a drawing?
Send your part number, pin-out or drawing. An engineer will reply by email.