D38999 Series III Connectors

d38999 series iii conesys

D38999 Series III circular connectors are high-performance cable to panel interconnects suitable for military, aerospace and harsh environment applications. NYKCS is a fully approved value-add distributor (VAD) for Conesys. We can, therefore, assemble connectors to meet your specific requirements. Contact us today for the best price and fast delivery.

The MIL-DTL-38999 Series III  range of military connectors (commonly known as D38999 III) features a number of body styles, contact termination options, body materials and platings. Consequently, these connectors suit a wide variety of electronic, mechanical and environmentally demanding applications. Up to 128 contacts are available in a number of defined high-density insert arrangements with a reliable tri-start coupling.


We are the most competitively priced supplier of approved MIL-DTL-38999 Series III connectors. NYKCS is fully approved to AS9100 Rev D and can assemble to meet your requirements. Contact us now for fast turnaround in 24 hours from receipt of order.

Conesys MIL-DTL-38999 Series III

How to Order Guide

Part Number Breakdown Tables

Part Number Resources

Value-Add Assembly

value add assembly d38999 part mark

In house assembly

In-house assembly enables NYKCS to supply a huge range of approved components quickly and efficiently. Thereby meeting each customer’s specific requirement for MIL-DTL 38999 Series III.

value add assembly d38999 routing paperwork

Approved to AS9100 Rev D

The assembly facility is fully approved to AS9100 Rev D. This provides end to end traceability and documentation that meets the needs of the most demanding supply chain.

value add assembly d38999 kitting from stores

Flexible scheduling

The latest workflow management solutions enable NYKCS to support complex order books and short production runs of MIL-DTL-38999 alongside our extensive range of mil-spec interconnect products.

Product Features

  • Sizes and Inserts: 9 Shell sizes, 52 Insert arrangements;
  • Plating: Black Zinc Nickel, Olive Drab, Electroless Nickel;
  • Coupling: Triple-start threaded coupling design, rapid advance, self-locking and full-mate indicator, keyed and Scoop-Proof;
  • EMI Shielding: up to 65dB minimum at 10 GHz;
  • Mating Speed: 360°, one full turn to full mate;
  • Test Voltage (Sea Level): up to 2300 VRMS;
  • Suggested Operating Voltage (Sea Level): up to 900 AC(RMS), 1250DC;
  • Operating Temperature: -65°C to +200°C (-85°F to +392°F) depending on shell material, and finish;
  • Vibration: Wired and mated connectors withstand the following vibration levels:
    • Sine vibration where connector samples with simulated accessory load are subjected to simple harmonic motion from 10 to 2,000 Hz in three mutually perpendicular axes, in 20 minutes, sweeps, for 12 hours in each axis at velocity of 254 mm/sec from 10-50 Hz, displacement of 1.5 mm from 50-140Hz and acceleration of 60G from 140-2,000Hz;
    • Random Vibration per MIL-STD-1344, method 2005, test condition V at ambient temperature and test condition VI, Letter “J” at elevated temperature.
  • Fluid Resistance: Connectors resist specified immersions in MIL-PRF-7808, MIL-PRF-23699, MIL-PRF-5606, M2-V Chevron oil, Coolanol 25, MIL-DTL-83133 (JP-8), MIL-DTL-5624 (JP-4, JP-5), SAE-AMS1424 Type I, and other solvents and cleaning agents;
  • Shock: Pulse of approximate half sine wave of 300 G ± 15 percent magnitude with duration of 3 ± 1 milliseconds applied in three axes;
  • Corrosion Resistance: Military Classes K, W and S, withstand 500-hour salt spray. Class F withstands 48-hour salt spray, Commercial RoHS Classes:BN*, BZ*, ZC*. Consult factory for T and Z class availability;
  • Durability: Minimum of 500 mating cycles.

D38999 'How to Order' Guide

1.  How and where will this connector be used? The available Shell Style's support various mounting options to suit your application.

2. What environment will this connector be used in? The available Service Class's support a range of environmental specifications to meet the demands of your application.


3.  What are the electrical requirements? The Shell Size will be dictated by your circuit demands so, therefore, your Contact Arrangement.

4. Which half of your circuit is active? This will define your Contact Style, i.e. whether your connector should have Pins or Sockets.

5.  Do you need to prevent mismating with similar neighbour connectors? Define if your connector needs a Polarising Position or insert N for none.

The tables below will assist you to construct an official mil-spec part number for a MIL-DTL-38999 series III connector. Many of the connector OEM’s have their own proprietary part numbers which we can cross-reference to and from the mil part numbers. NYK Component Solutions assembles in-house for Conesys and is also a distributor for other leading OEM’s. We are in a unique position to provide unbiased advice for you to meet your technical and logistical requirements.

Part Number Breakdown Tables

Example Part Number:

D38999 / 20 F A 35 P N

D38999 /20 F A 35 P N
Connector Type Shell Style Service Class Shell Size Contact Arrangement Contact Style Polarizing Position

Shell Style

Prefix Shell Style Description Available In Class
D38999/20 wall mount receptacle F,G,J,K,M,S,W
D38999/21 hermetic seal box mount receptacle H,N,Y
D38999/23 hermetic seal jam nut receptacle H,N,Y
D38999/24 jam nut receptacle F,G,J,K,M,S,W
D38999/25 hermetic seal solder mount receptacle H,N,Y
D38999/26 straight plus, self-locking F,G,J,K,M,S,W
D38999/27 hermetic seal weld mount receptacle H,N,Y

Service Class

Class Description Material Finish Temperature
C environmental aluminium non-conductive anodize -65deg - 200degC
F environmental aluminium electroless nickel -65deg - 200degC
G environmental, space grade aluminium electroless nickel -65deg - 200degC
H hermetic, space grade stainless steel electroless nickel -65deg - 200degC
J environmental composite cadmium olive drab, 500 hr. salt spray -65deg - 175degC
K environmental, firewall stainless steel passivated -65deg - 200degC
L environmental stainless steel electrodeposited nickel -65deg - 200degC
M environmental composite electroless nickel -65deg - 200degC
N hermetic stainless steel electrodeposited nickel -65deg - 200degC
P environmental aluminium pure electrodeposited aluminium -65deg - 175degC
R environmental aluminium electroless nickel -65deg - 175degC
S environmental stainless steel electrodeposited nickel -65deg - 200degC
T environmental aluminium nickel flurocarbon polymer -65deg - 175degC
W environmental aluminium cadmium olive drab, 500 hr. salt spray -65deg - 175degC
X environmental aluminium cadmium olive drab, 500 hr. salt spray -65deg - 175degC
Y hermetic stainless steel electroless nickel -65deg - 200degC
Z environmental aluminium zinc nickel -65deg - 175degC

Class R same as F, but higher corrosion requirement
Class X same as W, but higher corrosion requirement

Insert Configurations

d38999 series iii insert configuration table low
d38999 series iii insert configuration table

Contact Ratings

For information about the maximum contact rating for d38999 III connectors please see the table below:

Contact Size Test Current (A) Maximum Millivolt Drop
Crimp Solder
Standard Hermetic Standard Hermetic
22M 3 2 30 20 60
22D 5 40
22 5 3 40 20 85
20 7.5 5 35 20 60
16 13 10 25 20 85
12 23 17 25 85
d38999 series iii polarization table

Polarization Notes: Numbers in table are angle of rotation in degrees.

  • from main key looking clockwise onto front face of plug
  • from main keyway looking anticlockwise onto front face of receptacle

Keyway identification ‘N’ is normal.

Insert arrangements do not rotate with the main keyway.

Crimp Tool Reference Table

Contact Type Size of Contacts Contacts Filler Plugs Plastic Tool Insertion/Removal Metal Tool Insertion Metal Tool Removal Crimp Tool Positioner- Turret Head Second Crimp Tool
Pin 22D M39029/58-360 MS27488-22-1 M81969/14-01 M81969/8-01 REV B M81969/8-02 REV B M22520/2-01 M22520/7-07
Socket 22D M39029/56-348 MS27488-22-1 M81969/14-01 M81969/8-01 REV B M81969/8-02 REV B M22520/2-01 M22520/7-05
Pin 20 M39029/58-363 MS27488-20-1 M81969/14-10 M81969/8-05 M81969/8-06 M22520/1-01 M22520/7-08
Socket 20 M39029/56-351 MS27488-20-1 M81969/14-10 M81969/8-05 M81969/8-06 M22520/1-01 M22520/7-08
Pin 16 M39029/58-364 MS27488-16-1 M81969/14-03 M81969/8-07 M81969/8-08 M22520/1-01 M22520/7-04
Socket 16 M39029/56-352 MS27488-16-1 M81969/14-03 M81969/8-07 M81969/8-08 M22520/1-01 M22520/7-04
Pin 12 M39029/58-365 MS27488-12-1 M81969/14-04 M81969/8-09 M81969/8-10 M22520/1-01 M22520/1-04
Socket 12 M39029/56-353 MS27488-12-1 M81969/14-04 M81969/8-09 M81969/8-10 M22520/1-01 M22520/1-04
Pin 8 Twinax M39029/90-529 MS27488-8-1 M81969/14-12 M81969/46-06 M81969/14-12 M22520/2-01 M22520/2-37 M22520/5-01
Socket 8 Twinax M39029/91-530 MS27488-8-1 M81969/14-12 M81969/46-06 M81969/14-12 M22520/2-01 M22520/2-37 M22520/5-01


Integrated Backshell D38999 Connectors

Built to conform with the MIL-DTL-38999 series III specification integrated backshell connectors are fully interminable and interchangeable with D38999 III products. These connectors offer the performance advantages of D38999 with the following benefits over a traditional connector/backshell pairing:

  • quicker assembly;
  • space saving;
  • lower weight;
  • time-saving during ordering;
  • reduced inventory holding.

The one-piece shell construction completely integrates the straight backshell enabling screen termination by either band or spring. They are manufactured in both aluminium and stainless steel with various plating available, including Black Zinc Nickel across the 3 shell styles.

integrated backshell d38999 iii

Integrated Backshell Part Number Development Table

Conesys d38999 iii integrated part number table download

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EMI/RFI Environmental Backshells



Need accessories? These circular connectors can be ordered with a very broad range of compatible accessories to suit different cable and installation requirements. Some of these can be found on the connector backshells and accessories Page. Your NYK Component Solutions specialist can advise you further.