Low-noise traveling-wave tube

An expression for the theoretical noise factor is given and the method of measurement is described. The tube is all-metal with coaxial input and output connections. Over the band 4200-5200 Mc/s the gain is 15 db and the n.f. 10 db. The max. voltage is 650 V and the beam current 0.5 mA, H = 275 gauss. A velocity jump is used in the electron gun. A similar tube with gain increased to 30 db is being designed.