Large-power radio frequency amplifier

This report describes some aspects of amplifiers with frequencies and outputs in the range of about 100 KHz to 200 MHz and 100 kW to 1 MW, respectively. In particular, the report is focused on major typical radio frequency amplifiers which have been developed by the authors, and electronic tubes used in these amplifiers. Capacitor coupling is mainly used in output power coupling circuits because such circuits are simple in structure and easy to adjust over a wide range of variable frequencies. In a quarter wave length circuit, output power coupling is made in the neighborhood of the vacuum tube, but the voltage near the tube decreases at higher frequencies. Thus a 3/4 wave length circuit is used at higher frequencies, with output power coupling made at an appropriate voltage. Specifications and features of typical radio frequency output cavities which have been developed by the authors are then described. A coaxial cylinder type quarter wave length amplifier presented has two variable frequency ranges which are shifted by changing the length of the cylinder. Another amplifier, which is of a coaxial angular type with a 3/4 wave ength circuit, is also described. (Nogami, K.)