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

4.6.6.2 Voltage drop for dc filters. The voltage drop shall be determined in accordance with figure 3.

Measurements shall be made by using a dc reading meter with the filter carrying rated current. At the manufacturer's

option, dc resistance can be measured as specified in 4.6.7 for specification sheets MIL-PRF-28861/6 and

MIL-PRF-28861/12. The equivalent dc voltage drop can then be calculated.

4.6.7 DC resistance (see 3.12). Filters shall be tested in accordance with method 303 of MIL-STD-202. Test is

optional when a dc voltage drop test is performed.

4.6.8 Radiographic inspection (see 3.13). Filters shall be tested in accordance with method 209 of MIL-STD-202.

The following details and exceptions shall apply:

a. Radiographic quality: The radiograph shall render a clear sharp image of the penetrameter.

b. Image quality indicator: A radiograph of the penetrameter shall be included on each radiograph film. The

penetrameter may be made from a sample filter of the same type as the filter being radiographed, with an

AWG number 48 tungsten wire mounted across the filter body.

c. Positions of specimen: Two views normal to the major axis of the part shall be taken. One view shall be

90 degrees from the other.

d. Evaluation of images: Special kinds of viewing equipment; magnifying glass of 10X magnification or a 7X

optical comparator.

e. Examination: The filter inspection shall include, but not be limited to, inspection for faulty lead connections,

misalignments of internal parts, solder defects, and physical damage of electrical elements. Typical filter

construction of a circuit filter is shown on figure 4.

(1)

Extraneous material.

(a) Solder which is firmly attached to the center conductor or case with a wetting angle > 45� is

cause for rejection (see figure 7). Unattached solder balls and particles are unacceptable when:

(1) Not firmly imbedded in potting material.

(2) The clearance between line and ground potential is less than .010 inch (0.25 mm).

(b) There shall be no solder splash on the winding or the capacitor. For defect example, see figure 5d.

sides of a capacitor in one view is cause for rejection.

(d) There shall be no metallic objects bridging the coil to the capacitor, nor contact between coil and

capacitor. For defect example, see figures 6a and 6b.

(e) There shall be no solder bridge or metallic objects between the capacitor and the ferrite bead.

(2)

Tubulet fill: Minimum tubulet solder fill shall be 50 percent of the tubulet inner diameter or .020 inch,

(0.51mm) whichever is less; see figure 8.

(3)

Internal damage: There shall be no nicks, gouges, cracks, or other imperfections in the wire, core,

capacitor, or other internal elements. For defect example, see figure 6f, figure 6g, and figure 6i.

(4)

Alignment of capacitors: The capacitor element shall be properly seated within its defined location

and shall not be tilted or misaligned more than 10 degrees with respect to the case centerline. For

defect example, see figure 6g.

(5)

Bonds: There shall be no evidence of improper bonding (defective welds) on internal lead

connections.