MIL-PRF-39005 Resistors, Fixed, Wirewound \(Accurate\), Nonestablished Reliability, Established Reliability, General Specification ForThis specification covers the general requirements for nonestablished reliability \(non-ER\), established reliability \(ER\), accurate, wire-wound, fixed resistors that have a maximum resistance tolerance of 1 percent and a high degree of stability with respect to time under specified environmental conditions. The resistors are capable for continuous full-load \(or voltage\) operation at any ambient temperature up to 125??C, and when derated, up to 145??C \(see 6.5\). They are not capable for application where the alternating current \(ac\) characteristics are of critical importance. ER resistors have life failure rates \(FR\) ranging from 1.0 percent to 0.001 percent per 1,000 hours \(see 1.2.1.5\). These FR are established at 60-percent confidence level on the basis of the life tests. The FR, identified by the appropriate symbol, is referred to operation at full rated voltage and temperature.

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MIL-PRF-39005G

f. Measurement during shock: Each resistor shall be monitored to determined electrical discontinuity

by a method which shall at least be sensitive enough to monitor or register, automatically, any

electrical discontinuity of 0.1 millisecond or greater duration.

g. Measurement after shock: DC resistance shall be measured as specified in 4.8.5.

h. Examination after test: Resistors shall be examined for evidence of mechanical and electrical

damage.

4.8.13 Vibration, high frequency (see 3.17). Resistors shall be tested in accordance with method 204

of MIL-STD-202. The following details and exceptions shall apply.

a. Mounting of specimens: Resistors shall be mounted in relation to the test equipment in such a

manner that the stress applied is in the direction which would be considered most detrimental.

Resistors shall be rigidly mounted on appropriate jig fixtures with their bodies restrained from

movement and their leads supported at a distance .375 inch �.0625 inch (9.53 mm �1.588 mm)

from the resistor body. These fixtures shall be constructed in a manner to ensure that the points of

the resistor mounting supports will remain in a static position with reference to the vibration table.

b. Test leads: Test leads used during this test shall be no larger than AWG size 22 stranded wire, so

that the influence of the test lead on the resistor will be held to a minimum. The test lead length

shall be no longer than necessary. A shielded cable, which may be necessary because of the field

surrounding the vibration table, shall be clamped to the resistor mounting jig.

c. Measurement before vibration: DC resistance shall be measured as specified in 4.8.5.

d. Test condition: D (.06 inch double amplitude or 20 G, whichever is less, with 10 through 2,000 Hz

frequency).

e. Motion: In each of three mutually perpendicular planes; initial plane shall pass through the resistor

axis and terminals, and the other two planes shall be mutually perpendicular.

f. Measurements during vibration: Each resistor shall be monitored to determine electrical

discontinuity by a method that shall at least be sensitive enough to monitor or register,

automatically, any electrical discontinuity of 0.1 millisecond or greater duration.

g. Measurement after vibration: DC resistance shall be measured as specified in 4.8.5.

h. Examination after test: Resistors shall be examined for evidence of mechanical and electrical

damage.