MIL-PRF-27208 Resistor, Variable, Wirewound, Nonprecision General Specification ForThis specification covers the general requirements for multiturn, lead-screw actuated and single turn wirewound, variable resistors with a contact bearing uniformly over the entire surface of the entire resistive element, wound linearly, when positioned by an actuator. These resistors are capable of full load operation \(where maximum resistance is engaged\) at maximum ambient temperature of 85 Degrees C, and are capable for continuous operation when properly derated, at a maximum temperature of 150 Degrees C \(see figure 2\). These resistors have a resistance tolerance of ┬▒5 percent \(see 3.1\).

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MIL-PRF-27208F

A.5.3 Solder dip/retinning options. The manufacturer (or authorized category B or C distributor) may solder

dip/retin as follows:

a. After the 100 percent group A screening tests. Following the solder dip/retinning process, the electrical

measurements required in group A, subgroup 1, test shall be repeated on the lot. Group A, subgroup 1, lot

rejection criteria shall be used. Following these tests, the manufacturer shall submit the lot to the group B

solderability test as specified in 4.7.21.

b. As a corrective action, if the lot fails the group A solderability test, the lot may be retinned no more than two

times. The lot after retinning shall be 100 percent screened for group A electrical requirements (dc

resistance) and parts failing (lot not exceeding PDA for group A, subgroup 1, see (4.6.1.2.1.1) these screens

shall not be supplied to this specification. If electrical failures are detected after the second retinning

operation exceeding 1 percent of the lot shall not be supplied to this specification.

c. After the group A inspection has been completed: Following the solder dip/retinning process, the electrical

measurements required in group A, subgroup 1, 100 percent screening test shall be repeated on 100 percent

of the lot. The PDA for the electrical measurements shall be as for the subgroup 1 tests. Following these

tests, the manufacturer shall submit the lot to the group A solderability test as specified in 4.7.21.

Custodians:

Preparing activity:

Army - CR

DLA - CC

Navy - EC

Air Force - 11

DLA - CC

Review activities:

(Project 5905-2005-009)

Army - AR, AT, AV, MI

Navy - AS, MC, OS

Air Force � 19

NOTE: The activities listed above were interested in this document as of the date of this document.

Since organizations and responsibilities can change, you should verify the currency of the information

above using the ASSIST Online database at https://assist.daps.dla.mil.