MIL-PRF-19E
6.4 PIN. This specification requires a PIN that describes technology and appropriate references to associated
6.5 Dissimilar metals. Unless suitably protected, metals such as brass, copper, or steel should not be used in
intimate contact with aluminum alloys.
6.6 Power rating. The power ratings given on the detail specifications (see 3.1) apply at temperatures up to
+40OC, with the resistors mounted on metallic panels thermally equivalent to those specified in 4.7.8.1. Resistors
operated at ambient temperatures above +40OC should be derated in accordance with figure 4. Satisfactory
operation cannot be assumed at any temperature, if the resistor is not mounted on a metallic panel thermally
equivalent to that specified in 4.7.8.1. such a panel serves as a "heat sink" and dissipates some of the heat generated
in such a resistor.
6.7 Nominal maximum current rating. The nominal maximum current rating of resistors is as shown in table XIV
where W is rated wattage for taper A (linear) resistors and R is the nominal total resistance.
TABLE XIV. Maximum permissible current.
Resistor
High resistance
Low resistance
section
Taper A (linear)
W /R
Taper C and F
2.24 W
0.745 W / R
(nonlinear, 10 percent)
R
6.7.1 Suggested mounting fixture. A suggested mounting fixture for the shock and high-frequency vibration tests is
shown on figure 6.
6.8 Tin whisker growth. The use of alloys with tin content greater than 97 percent, by mass, may exhibit tin whisker
growth problems after manufacture. Tin whiskers may occur anytime from a day to years after manufacture and can
develop under typical operating conditions, on products that use such materials. Conformal coatings applied over top of
a whisker-prone surface will not prevent the formation of tin whiskers. Alloys of 3 percent lead, by mass, have shown to
inhibit the growth of tin whiskers. For additional information on this matter, refer to ASTM-B545 (Standard Specification
for Electrodeposited Coatings of Tin).
6.9 Subject term (key word) listing.
Control shaft
Potentiometer
Linear taper
Nonlinear taper
6.10 Environmentally preferable material. Environmentally preferable materials should be used to the maximum
extent possible to meet the requirements of this specification. Table X lists the Environmental Protection Agency
(EPA) top seventeen hazardous materials targeted for major usage reduction. Use of these materials should be
minimized or eliminated unless needed to meet the requirements specified herein (see section 3).
TABLE XV. EPA top seventeen hazardous materials.
Benzene
Dichloromethane
Tetrachloroethylene
Cadmium and Compounds
Lead and Compounds
Toluene
Carbon Tetrachloride
Mercury and Compounds
1,1,1 - Trichoroethane
Chloroform
Methyl Ethyl Ketone
Trichloroethylene
Chromium and Compounds
Methyl Isobutyl Ketone
Xylenes
Cyanide and Compounds
Nickel and Compounds
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