A microwave feed-forward experiment

Both one- and two-stage feed-forward control were applied to α 4-GHz, 461A, traveling-wave tube, used in the TD-3 radio relay system, to demonstrate the feasibility of reducing distortion to a sufficiently low level for single sideband transmission. With a single stage, and discounting extraneous losses, the third-order, MS, distortion measure was reduced by 38 dB over a selected 20-MHz channel, and the application of the second stage rendered distortion unobservable with our instruments. These results were time independent with continuous performance over several months.