Some notes on design of a high-power radio-telegraphic transmitter using thermionic valves

The paper deals with certain specific details of design and operation of the high-power valve transmitter installed at Rugby radio station, and is divided into six parts. Part I discusses the arrangement of the coupled aerial circuit of a valve transmitter, and shows that certain circuits have considerable advantages over others in respect of the elimination of harmonics. Part II indicates the considerations which govern the choice of the electrical proportions of the intermediate and aerial circuits, simple formulae being given for the calculation of the different quantities involved. Part III deals with the question of the design of large inductance coils, and compares measured values of the high-frequency resistance of certain coils with the calculated values. Part IV contains some notes on valve-circuit design, compares two conditions of operation of a valve transmitter and gives an analysis of the present operating condition at Rugby. The comparative operation of valves in low- and high-power transmitters is also discussed. Part V gives oscillograms of the shape of signals emitted when using different keying arrangements, and indicates the improvement obtained in certain cases. The transients due to keying are discussed briefly also. Part VI gives the results of recent signal measurements and a schedule of readings under present normal working conditions.