EMI Filters - Captor Corporation

Aware of Captor Corp’s expertise in electromagnetic interference, a customer contacted us for fabrication & design of a custom EMI filter.

This filter needed to handle AC and DC power and signal lines for a systems application designed for aerospace and military uses. We worked with the customer to create a filter with operating voltages and currents of 115 VAC, 3-phase, 400 Hz, 4 amps; 270 VDC, 12 amps, 2 lines; 5 VDC, 500 mA for 14 signal lines. Input termination is a D38999 military connector and the output is a M24308 military D-sub connector. The filter measured 7.00″ x 4.00″ x 5.00″, weighed 6 lb, and had operating temperature of -55° to +105°C and non-operating temperature of -55° to +125°C. The chassis was constructed of cold rolled steel with electro tin-lead plated finish and threaded inserts for mounting. We performed full electrical and environmental testing to ensure proper functionality.

The following table details this EMI filter fabrication project, including all testing standards that were met. For additional inquiries, please feel free to contact us.



Filters AC power lines, DC power lines, and signal lines for system application.

Operating Voltages and Currents

115 VAC, 3 phase, 400 Hz, 4 amps
270 VDC, 12 amps, 2 lines
5 VDC, 500 mA for 14 signal lines

Electrical Testing Performed

Insertion Loss: MIL-STD-220
DWV: MIL-PRF-15733 4.6.5 and MIL-STD-202, Method 301
Insulation Resistance: MIL-PRF-15733 4.6.7 and MIL-STD-202, Method 302, Test Condition A
Capacitance: MIL-PRF-15733 and MIL-STD-202, Method 305
Voltage Drop: MIL-PRF-15733 4.6.8
Burn-In at rated voltage and current

Environmental Testing Performed

Vibration: MIL-PRF-15733 and MIL-STD-202, Method 204, Test Condition D
Shock: MIL-PRF-15733 4.6.16 and MIL-STD-202, Method 213, Test Condition C
Thermal Shock/Cycling: MIL-PRF-15733 and MIL-STD-202 Method 107, Test Condition A
Humidity: MIL-STD-202, Method 103, Test Condition B
Altitude: MIL-STD-202, Method 105, Perform DWV and IR

Input Termination

D38999 Military Connector

Output Termination

M24308 Military D-Sub Connector

Overall Part Dimensions

7.00 x 4.00 x 5.00 inches

Estimated Part Weight

6.0 pounds

Operating Temperature Range

-55° to +105°C

Non-Operating Temperature Range

-55° to +125°C

Chassis Material

Cold Rolled Steel

Chassis Finish

Electro Tin-Lead Plated


Threaded Inserts

Industry for use

Aerospace, Military

Standards met

MIL-STD-461, Customer supplied specification, AS9100 quality system, ANSI/IPC-A-610 Class 3 workmanship