The 6116 (Bendix® Type TK-62) tube is a ruggedized low voltage thermally tuned X-band reflex klystron, de- signed for use as a CW power source over the frequency range of 8500 to 9660 Mc./sec. Thermal tuning of the klystron is accomplished by means of a diode included within the vacuum envelope, the plate of which comprises one wall of the klystron cavity. As diode voltage, and hence current, is increased, expansion of the plate results in corresponding changes in the klystron cavity gap spac- ing causing the tube to tune. The tuning speed over the required frequency range is .7 to 3 seconds. With the exception of the diode tuner, the 6116 may be considered a ruggedized version of the 2K45 with equivalent outline dimensions and