Life test of tube 11S has continued to 380 hours with RF operating characteristics still within specifications. Some missing pulses are discernible, but the percentage has not increased above that which was present after 130 operating hours. Peak RF power, heater power, pulse voltage, and current have also remained essentially unchanged. Tests were conducted to determine the presence, if any, of end-hat emission. Conclusions were established in the last quarterly report that end of life of tube number 121 was reached after 120 operating hours due possibly to end-hat emission, as evidenced by higher DC emission than theoretical perveance predicts. Further tests on this tube were terminated because of a previously scheduled dissection of the tube at Harry Diamond Laboratories. Tests of DC emission on several other tubes with life histories varying from 5 to 100 hours did not, however, reveal the same condition as tube number 121. Measurements were then taken of peak pulse voltage versus average anode current to observe voltage cut-off characteristics as an indicator of end-hat emission. Data taken on fresh tubes as compared with tubes that showed deteriorated performance did not establish evidence of any end-hat emission. In accordance with a request from Harry Diamond Laboratories, tube 3S, which successfully passed the shock test requirements of the BL-234C specification, was submitted to the same test with heater operating. No heater shorts or open resulted, and the tube continued to operate after completion of the test.