MIL-PRF-23648F
4.8.8 Low temperature storage (see 3.10).
a. Mounting: Mounting in accordance with 4.8.2.3a is optional. Thermistors should be isolated from
metal surface of cold boxes.
b. Procedure: Zero power resistance shall be measured at 25°C as specified in 4.8.2. Within 1 hour
after this measurement, the thermistors shall be placed in a cold chamber at room temperature.
The temperature shall be reduced to -62°C ±3°C, and the thermistor maintained at that
temperature for a period of not less than 3 hours. (For conformance inspection only, at option of
the supplier, the thermistor may be placed in the cold chamber when it is already at the extreme
low temperature.) The thermistors shall then be removed from the chamber and stabilized at
room temperature. The final zero power resistance at 25°C shall be measured as specified in
4.8.2, not less than 1 hour from termination of the test and within a 24 hour period. The
thermistors shall then be examined for mechanical damage.
4.8.9 High temperature storage (see 3.11). Measure the zero power resistance of all test samples.
a. Mounting: Mounting in accordance with 4.8.2.3.a is optional. Thermistors should be isolated from
metal surfaces of ovens.
b. Temperature: The temperature shall be within ±2 percent (in °C) of the maximum operating
temperature specified (see 3.1).
c. Load condition: No load.
d. Duration: Test duration shall be 100 hours.
e. Resistance measurement: Measure and record zero power resistance 1 hour to 24 hours later in
an ambient temperature 25°C.
4.8.10.1 Test procedure. The test procedure shall be as follows:
a. Measure zero power resistance at 25°C and 75°C (see 4.8.2).
b. Mounting: See 4.8.2.3.a.
c. Power supply: Use a dc regulated or battery power supply.
d. Place thermistors in a still air controlled chamber with a minimum volume of 1,000 times the
thermistor body and test fixture. Chamber temperature 25°C ±1°C.
e. Loading (see figure 1): Adjust Eth and Ith for zero power resistance values of 75°C. Keep load for
maximum of 15 minutes.
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