Downloaded from https://www.everyspec.com MIL-STD-1311C 31 January 2001 4.7 Additional testing. The manufacturer may make such additional tests as he may deem necessary to insure proper control of his product. 4.8 General test conditions. 4.8.1 Order of testing. Conformance inspection tests may be conducted in any order, at the discretion of the manufacturer. For qualification testing (verification), the following tests, when specified, shall be performed after all other tests in any sequence: bump, emission, pulse cathode current, rough handling (formerly drop test), shock, and vibration. 4.8.2 Ambient conditions.
Unless otherwise specified, test temperature, relative humidity, and atmospheric pressure conditions shall be in accordance with GENERAL REQUIREMENTS of MIL-STD-202. 4.8.3 Calibration of measuring and test equipment. Calibration and certification procedures for standards and instruments used to test and measure completely assembled electron tubes acquired in accordance with MIL-PRF-1, shall be as specified in ANSI- Z540.1-94. In addition, the following requirements shall apply: a. The accuracy of a calibrating instrument shall be at least four times greater than that of the item being calibrated. b.
Calibration intervals shall be established on the basis of stability, purpose, and degree of usage for the standards and instruments and shall not exceed a 1-year interval except as indicated below. Intervals shall be shortened as required to assure continued accuracy, as evidenced by the results of preceding calibrations, and may be lengthened only when the results of previous calibrations provide definite indications that such action will not adversely effect the accuracy of the system. The individual changes shall be approved by the qualifying activity (Code DSCC-VQE, Defense Supply Center Columbus, P.O. Box 3990, Columbus, OH 43216-5000). 4.8.4 Accuracy of measurements.
The specified limits are for values obtained with the specified test conditions and measuring equipment of accuracy consistent with general industry practice and calibrated in accordance with ANSI-Z540.1-94. Allowances are made for normal distribution and measuring instrument accuracy in establishing test specification sheet test conditions and test limits. Accuracy of measurements shall be appropriate to the test parameter(s) being measured and specific point instrument calibrations may be utilized when better accuracy than that specified and maintained for the basic measuring instrument is desired. 4.8.5 Holding periods.
After completion of all manufacturing processes through final pinch-off of the vacuum envelope, the tube shall be held non-operating for minimum periods as specified in the following category listing. (NOTE: Tube categories not listed shall be held for a minimum of 24 hours.) During this holding period, external processes may be completed that do not require the application of high voltage. These processes include the completion of painting, decals, leads, magnets, mounting flanges, connectors, tuner, and other miscellaneous external hardware. Required testing performed after the holding period shall be designated on the TSS by a note.
These tests shall be the first conducted after the holding period. Other required testing shall be conducted before or after the holding period, at the manufacturer’s option. 6