Downloaded from https://www.everyspec.com MIL-STD-1311D METHOD 1506 HEATER-CYCLING LIFE 1. Cycling. A complete cycle is made in a 2-minute period as follows: 1 minute "on", 1 minute "off". Duration of the cycling test shall be 2,000 cycles. The heater-voltage supply shall have a regulation of not more than 3.0 percent (no-load to steady-state load). Heater-cathode voltage shall remain on continuously. Any tube which shows an open heater, open-cathode circuit, heater-cathode short, or fails to meet any specified life-test end-point limit(s) for this test prior to the completion of the cycling test shall be considered a defective tube.
A leakage current in excess of 500 µ A dc between the heater and cathode shall be considered a heater-cathode short. Sampling shall be as specified in MIL-PRF-1, section 4. This is a destructive test. 2. Use of defectives. Electrical or mechanical defectives may be used for this test except for the following: a. Tubes shall be within initial limits for heater or filament current. b. Tubes shall meet the post-heater cycling acceptance criteria. METHOD 1506 1506-1 19 April 1968