MIL-PRF-39035E
4.8.5.1 Total resistance. Total resistance shall be measured as specified in 4.8.5, between the resistance-element
end terminals (terminals 1 and 3 on figure 1), with contact arm positioned against a stop. The positioning of the
contact arm and terminal shall be the same for all subsequent measurements of the total resistance on the same
specimen (see 3.11.1).
4.8.5.2 End resistance. The contact arm shall be positioned at the extreme counterclockwise limit of mechanical
travel, and the resistance shall be measured as specified in 4.8.5 between the contact arm and the corresponding
end terminal. The contact arm shall then be positioned at the extreme clockwise limit of the mechanical travel, and the
resistance shall be measured as specified in 4.8.5 between the contact arm and the corresponding end terminal.
During this test, precaution shall be taken to insure that rated current of the resistance element is not exceeded.
Clockwise signifies the direction of rotation of the operating shaft when the resistor is viewed from the shaft end
(see 3.11.2).
4.8.6 Immersion (not applicable to L type terminations) (see 3.12). The surface shall be cleaned of any foreign
matter immediately before immersion.
Precondition: The resistors shall be preconditioned in an oven at 125OC ±5OC for 13 ±2 minutes, or use a
a.
fluorocarbon bath maintained at 125OC ±5OC for a period of 1.5 ±0.5 minutes. Upon completion of
precondition, allow resistors to stabilize to room temperature for approximately 13 ±2 minutes.
b.
Immersion: The resistors shall be immersed (not to exceed 30 samples) into a bath of fluorocarbon held
at 85OC +5OC, -0OC for a period of 60 seconds ±5 seconds. The resistor shall be completely submerged
in the bath, with no part at a depth of less than 1 inch. Resistors shall be shaken for a maximum of 5
seconds and shall remain in the bath for a period of 1 minute ±5 seconds. Visually examine resistors for
inadequate seals, as evidence by a continuous stream of bubbles emanating from any concentrated point
on the resistor.
c.
Dye penetrant verification: A five piece sample of the product exhibiting inconclusive evidence of
O
compliance to immersion requirements (see 3.12), shall be preconditioned in an oven stabilized at 125 C
±5OC for 13 ±2 minutes, or preconditioned in a fluorocarbon bath maintained at 125OC ±5OC for 1 minute
±5 seconds and immediately upon removal (within 5 seconds), shall be submerged in a dye penetrant
solution for 30 seconds minimum. The dye penetrant solution shall consist of 0.1 grams per liter, or
equivalent, of a soluble stain dye such as crystal violet dissolved in deionized water maintained at room
ambient. Upon removal from the dye solution, the sample shall be held at room temperature until external
surfaces are dry. The sample shall be carefully opened and examined under 10X to 30X for evidence of
dye penetration into the sealed cavity. Evidence of such penetration verifies loss of immersion seal, and
lack of such evidence verifies compliance to the requirements.
4.8.7 Actual effective electrical travel (see 3.13). The actual effective electrical travel shall be measured by placing
the resistor in a suitable device and circuit which will indicate both angular position of the operating shaft and voltage
output. The actual effective electrical travel will be the number of turns or degrees of the operating shaft in which a
change in contact-arm position gives a measurable change in voltage output.
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