EMCA’s Series A3 backshells deliver high-performance EMC shielding and environmental protection for mission-critical connector assemblies. Available in straight, 45°, and 90° configurations, these backshells are engineered for secure cable management and space-efficient routing in demanding environments. Featuring band termination / constant force spring (CFS) platforms and robust strain relief options, Series A3 supports quick, reliable installations across a wide range of MIL-DTL-38999 (D38999) Series III and IV connectors. Trusted in aerospace, and high-reliability industrial systems, this series offers proven performance in harsh operating conditions.
| A37-524 A37-525 A37-526 |
4 | J | 08 | KN | ||
|---|---|---|---|---|---|---|
| Basic part number | ||||||
| Shell size code |
ARefer to table A for the required Shell Size code
|
|||||
| Material and plating code |
CRefer to table C for the required Shell Finish code
|
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| Cable entry size |
BRefer to table B for the required Shell Entry Size code
|
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| Option knurled coupling ring |
* Please refer to datasheets for all other backshell types.
All dimensions in mm (inch) unless specified otherwise.
| Shell Size | Shell Size Code |
|---|---|
| 08 (A) | 1 |
| 10 (B) | 2 |
| 12 (C) | 3 |
| 14 (D) | 4 |
| 16 (E) | 5 |
| 18 (F) | 6 |
| 20 (G) | 7 |
| 22 (H) | 8 |
| 24 (J) | 9 |
| Entry Size Code | ØD2 min. | ØD3 max. |
|---|---|---|
| 03 | 4.7 (0.185) | 13.9 (0.547) |
| 04 | 6.3 (0.248) | 13.9 (0.547) |
| 05 | 7.9 (0.311) | 15.5 (0.610) |
| 06 | 9.5 (0.374) | 17.2 (0.677) |
| 07 | 11.1 (0.437) | 18.7 (0.736) |
| 08 | 12.7 (0.500) | 20.3 (0.799) |
| 09 | 14.2 (0.559) | 21.9 (0.862) |
| 10 | 15.8 (0.622) | 23.5 (0.925) |
| 11 | 17.4 (0.685) | 25.1 (0.988) |
| 12 | 19.0 (0.748) | 26.7 (1.051) |
| 13 | 20.6 (0.8115) | 25.1 (0.988) | 14 | 22.2 (0.874) | 29.9 (1.177) |
| 15 | 23.8 (0.937) | 31.5 (1.240) |
| 16 | 25.4 (1.000) | 33.1 (1.303) |
| 17 | 27.0 (1.063) | 34.7 (1.366) |
| 18 | 28.6 (1.126) | 36.3 (1.429) |
| 19 | 30.2 (1.189) | 37.9 (1.492) |
| 20 | 31.8 (1.252) | 39.5 (1.555) |
| 21 | 33.3 (1.311) | 41.1 (1.618) |
| 22 | 35.0 (1.378) | 42.7 (1.681) |
| 23 | 36.5 (1.437) | 44.3 (1.744) |
| 24 | 38.1 (1.500) | 45.9 (1.807) |
| Material & Plating Code | Technical Design | ROHS / REACH Complaint | Electrically Conductive | Salt Spray Resistance (MIL Spec) | Salt Spray Resistance (VG Spec) |
|---|---|---|---|---|---|
| J | Black Hybrid finish
|
Yes | Yes | 500 hrs | 5 days cyclic |
| U | Olive drab Hybrid finish
|
Yes | Yes | 500 hrs | 5 days cyclic |
| 5 | Electroless nickel Base material: Al- alloy. |
Yes | Yes | 48 hrs | 48 hrs |
| 2 | Zinc-Nickel black
|
Yes | Yes | 500 hrs | n.a. |
| 6 | Cadmium olive drab
|
No | Yes | 500 hrs | 5 days cyclic |
| 9 | Marine Bronze Material: CuAl10Ni5Fe4 (CW307G). No additional plating. |
Yes | Yes | n.a. | n.a. |
| 1 | Stainless Steel / passivated |
Yes | Yes | n.a. | n.a. |
A backshell on a D38999 connector serves several critical purposes: it provides robust mechanical strain relief to protect the cable connection, ensures effective environmental sealing against moisture and contaminants, and offers crucial EMI/RFI shielding to maintain signal integrity. By safeguarding the delicate cable-to-connector transition, the backshell guarantees reliable performance even in demanding environments.
Selecting the appropriate backshell for your D38999 connector hinges on several key factors dictated by your specific application. Consider the necessary level of shielding (EMI/RFI), the required degree of environmental sealing, and your preferred cable routing (straight, 45°, 90°). Other important aspects include the connector series and shell size compatibility, as well as the desired termination style, such as banding or constant force spring.
Yes, many D38999 backshells are specifically designed to provide effective EMI/RFI shielding. This is often achieved through conductive metal-to-metal contact between the backshell and the connector, along with reliable termination platforms like band straps or constant force springs. For example, our EMCA Series A3 backshells are engineered with robust shielding features to ensure optimal electromagnetic compatibility.
