Backward-wave oscillators for the 8000-18,000-megacycle band

Design and construction of research models of two backward-wave oscillators, covering the bands 7.6-12.4 and 11.6- 18.0 kmc, is described. These tubes are tuned purely electronically and cover their tuning ranges continuously with a power output of 25-mw absolute minimum. The highest electrode voltage used is 2100 volts; the over-all weight is about 7 pounds. These properties are achieved through a novel tube design which enables reduction of tube diameter where it is within the solenoid, and through use of a novel split magnet and rf match idea to enable reduction in necessary solenoid inner diameter.