MIL-PRF-22097 Resistors, Variable, Nonwirewound, Adjustment Type, General Specification ForThis specification covers the general requirements for multi-turn lead screw actuated and single turn nonwirewound, variable resistors with a contact bearing uniformly over the entire surface of the entire resistive element, when positioned by the actuator. These resistors are capable of full load operation \(where maximum resistance is engaged\) at a maximum ambient temperature of 70 Degrees C and 85 Degrees C, and are capable for continuous operation when properly derated, at a maximum temperature of 125 Degrees C and 150 Degrees C \(see figure 1\). These resistors have a resistance of ┬▒10 percent \(see 3.1\).

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MIL-PRF-22097J

Measurements during shock: Each resistor shall be monitored to determined electrical discontinuity of the

resistance element, between the contact arm and element, by a method that shall at least be sensitive

enough to monitor or register, automatically, any electrical discontinuity of 0.1 ms or greater duration.

Measurements after shock: Setting stability and total resistance shall be measured as specified 4.7.8.1 and

4.7.2.1, respectively.

Inspection after shock: Resistors shall be inspected for evidence of mechanical damage.

4.7.12 Vibration, high frequency. Resistors shall be tested in accordance with method 204 of MIL-STD-202

(see 3.17). The following details and exceptions shall apply:

Mounting: As specified in 4.7.11a.

Test leads: As specified in 4.7.11b.

Measurements before vibration: As specified in 4.7.11c.

Test condition D.

Measurement during vibration: As specified in 4.7.11e.

Measurements after vibration: As specified in 4.7.11f, and torque as specified in 4.7.7.1.

Inspection after vibration: Resistors shall be inspected for evidence of mechanical damage.

4.7.13 Salt spray (corrosion). Resistors shall be tested in accordance with method 101 of MIL-STD-202

(see 3.18). The following details shall apply:

Special mounting: As specified in 4.7.10a.

Test condition A.

Inspection after exposure: Resistors shall be inspected for corrosion.

4.7.14 Resistance to soldering heat (applicable to terminal types P, S, W, X, and Y only). Total resistance shall be

measured as specified in 4.7.2.1. All resistors terminals shall be immersed in a pot of molten solder at a temperature

350OC �10OC, for a period of 3.0 seconds �.5 second, to a point .125 inch (3.18 mm) from the entry of the terminal

into the resistor body. After a minimum of 3 hours have elapsed, total resistance shall be measured as specified in

4.7.2.1. Resistors shall then be inspected for evidence of mechanical damage (see 3.19).

4.7.15 Life. Resistors shall be tested in accordance with method 108 of MIL-STD-202 (see 3.20). The following

details and exceptions shall apply:

Method of mounting: Resistors shall be mounted by their normal mounting means, on a .625 inch (1.588

mm) thick, glass base, epoxy laminate. The resistors shall be so arranged that the temperature of any one

resistor shall not appreciably influence the temperature of any other resistor. There shall be no circulation of

air over the resistors other than that caused by the heat of the resistors

Test temperatures and tolerances: 70 C �5 C for characteristic A, and 85 C �5 C for characteristic C and

characteristic F.

Initial measurements: Measurements may be made inside or outside the chamber. Total resistance and

setting stability shall be measured as specified in 4.7.2.1 and 4.7.8.1, respectively.

After resistors have been stabilized at their respective temperatures for at least 8 hours, the resistance

between the end terminals, with the contact arm in the position for setting stability, shall be measured.