Travelling-wave tubes for 6-gigacycle-per second radio links

Two medium power travelling-wave tubes to give power outputs of 8 W and 12 W respectively at frequencies around 6Gc/s are described. The tubes operate at a helix voltage of 3000-3500 V and require an r.f. input of 1 mW for the quoted output powers. A fairly high efficiency is achieved by using a collector potential equal to about 2/3 the helix potential, the reduced collector dissipation permitting natural convection cooling. Electron beam focussing is by a periodic-permanent-magnet structure which is described in detail. The section on tube performance includes details of gain and power output, s/n ratio, leakage and attenuation, matching, phase characteristics, harmonic output and life. Tubes giving similar performance at frequencies up to 8.5Gc/s are in an advanced state of development.