electromagnetic interference. Filters furnished to the requirements of this specification contain shunting ceramic discoidal capacitors and series inductors \(FSC 5915\). Capacitors furnished to the requirements of this specification contain shunting ceramic discoidal capacitors \(FSC 5910\). For the purposes of this specification, feed-through capacitor types \(C circuit configuration\) are referred to herein as a filter. Passband power may be alternating current \(ac\) or direct current \(dc\) and the filters used primarily in the reduction of broadband radio frequency interference. This specification provides for two levels of product assurance requirements. Filters covered by this specification are capable of operation over the temperature range of -55 degrees C to +125 degrees C.

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MIL-PRF-28861D

3.5.4 Solder dip (retinning) leads. The manufacturer (or authorized category B or C distributor) may solder

dip/retin the leads of product supplied to this specification provided the solder dip/retin process has been approved by

the qualifying activity (see appendix A).

3.5.5 Threaded parts. Unless otherwise specified (see 3.1), all threaded parts shall be in accordance with

3.5.6 Inductive elements. Unless otherwise specified, the wire used when winding inductors shall have a

minimum diameter of .004 inch (0.10 mm) and shall be capable of meeting the requirements of MW-16, MW-20, MW-

35, or MW-36 of MW-1000, or equivalent. Inductors shall be inspected to ensure that the wire is not kinked or nicked

and that the insulation is continuous. For class S filters only, cores and ferrite beads shall be 100 percent inspected

for chipped coating, cracks, chips, and material cracks and chips (see 4.6.1.2b).

3.5.7 Capacitor elements.

3.5.7.1 Class B filters. Capacitor elements used in class B filters shall meet the requirements of MIL-PRF-31033

for class B except that qualification, group A, and group B inspections are not required. An outside capacitor

manufacturer with existing MIL-STD-790 approval may supply discoidal capacitors for use in MIL-PRF-28861 filters,

provided that manufacturer's discoidal capacitor line is audited and certified by the qualifying activity to the MIL-STD-

790 requirements. Required inspections are as follows:

a. In-process inspection.

b. Destructive physical analysis. Capacitors shall be examined as specified in MIL-PRF-31033.

3.5.7.2 Class S filters. Capacitor elements used in class S filters shall meet the requirements of MIL-PRF-31033

for class S except for qualification inspection. An outside capacitor manufacturer with existing MIL-STD-790 approval

may supply discoidal capacitors for use in MIL-PRF-28861 filters, provided that manufacturer's discoidal capacitor line

is audited and certified by the qualifying activity to the MIL-STD-790 requirements. Required inspections are as

follows:

a. In-process inspection.

b. Inspection of product for delivery (group A and group B inspections) except that the group B life test is not

required.

3.5.8 Solders. When solders are used in filters covered by this specification, the solder joint where the internal

wire exits through a glass seal on all filters and all solder joints on the solder-in style filters shall be made with solder

in accordance with J-STD-006, or equivalent, having a liquid point not less than 280�C or as specified (see 3.1). The

use of lead-free, tin alloy high temperature solders requires approval by the qualifying activity. The tin content of

lead-free high temperature solders shall not exceed 97 percent by mass. For further information and guidance on

soldering filters, see 6.4.3.

3.5.9 Potting (when applicable). When potting compound is used to secure the inductive elements, the inductive

elements shall be potted to at least 80 percent of their height so that the potting makes intimate contact with the case.

3.5.10 Weight (when applicable). Filters shall meet the weight requirements specified (see 3.1).

3.6 Visual inspection (class S filters only). Filters shall be inspected for anomalies as specified in 4.6.1.2.

3.7 Thermal shock and voltage conditioning. When filters are tested as specified in 4.6.2, they shall meet the

following requirements:

Insulation resistance (+125�C): Shall meet initial requirements (see 3.1) and, for class S broadband style

filters (MIL-PRF-28861/1 through MIL-PRF-28861/5), shall decrease no more than 50 percent from pre-voltage

conditioning measurement.