Downloaded from https://www.everyspec.com MIL-STD-1311D 2.2.2 Types other than reliable. If a short indication is obtained, the tapping cycle shall be repeated two more times. If a short indication is again obtained, the tubes shall be rejected as inoperable. 2.2.3 Filamentary types intended for dry-battery operation. The tube shall be tested for shorts between any elements, base pins having no connections and internal shields. A short circuit shall be 50,000 ohms or less regardless of duration. A minimum voltage of 20 V dc or peak ac shall be applied between adjacent elements. 2.3 Tapping procedure for other than receiving.
The tubes shall be mounted in the socket of the short test equipment and tapped three times on each of two planes 90 degrees apart. Sharp blows shall be delivered with a mallet consisting of a .125 inch (3.18 mm) diameter fiber rod inserted and glued into the small end of a No. 8 high quality cork 1.062 inches (26.97 mm) long and having a large diameter of .875 inch (22.22 mm) and a small diameter of .688 inch (17.47 mm). The overall length of rod and cork shall be 6 inches (152.4 mm). 3. Air leaks. Tubes shall be tested for air leaks as specified in method 1267. 4. Short and discontinuity detection (for power and transmitting tubes).
A hexaphase short and discontinuity system may be used as an alternate test. METHOD 1201C 1201-2 28 March 1975