Downloaded from https://www.everyspec.com MIL-STD-1311D METHOD 1027 TEMPERATURE CYCLING (NONOPERATING) 1. Purpose. To determine the ability of electron tubes to withstand ambient temperature cycling. 2. Equipment. A test chamber is required which is capable of temperature cycling the tubes over the specified temperature range. Separate hot and cold chambers may be used. 3. Procedure. The tubes shall be placed in the chamber and exposed to one temperature cycle, from room temperature, to 100 ° C, to -55 ° C, to room temperature, (or the reverse order may be used). The tubes shall be maintained at each temperature extreme long enough to stabilize, but not less than 5 minutes.
Temperature changes may be gradual; or, the manufacturer may place the tubes directly in a chamber at the high or low temperature, and, after stabilization, transfer them to the other chamber, either directly, or after allowing them to stabilize at room temperature. The temperature cycle test may be performed before painting and labeling, but after all assembly operations. 4. Acceptance criteria. At the conclusion of the cycle, gas switching tubes shall pass either the ignitor ignition time test (method 4401) or the firing time test (method 4486), whichever is appropriate. For other tubes, acceptance criteria shall be specified on the TSS. 5. Temperature cycling life test.
Gas switching tubes subjected to the temperature cycling life test shall pass either the ignitor ignition time test (method 4401), or the firing time test (method 4486), as appropriate, at the conclusion of the cycling, and shall pass the same end-point test again not less than 24 hours later. METHOD 1027 1027-1 19 April 1968