The Droitwich broadcasting station

This paper gives a description of a wireless broadcasting station recently built by the British Broadcasting Corporation at Droitwich, in Worcestershire. The station contains two transmitters, each giving a separate service, one having an aerial power of 150 kW and working on a ¿long¿ broadcasting wavelength, and the other a power of 50 kW and working on a ¿medium¿ broadcasting wavelength. The former is dealt with in greater detail than the latter, since it contains more features of technical interest. The paper, which gives a general description of the whole station, is divided into four parts. Part I deals with the objects and required performance of the station, and the effect of governmental and international regulations relating to broadcasting stations, particularly in connection with power and the choice of site. Part II gives a general explanation of the lay-out of the station, and the reasons for adopting certain types of plant. Part III deals mainly with the detailed design of certain apparatus not yet in common use, such as mercury-arc rectifiers for an output of 600 kW at 20 000 volts, and motor-generator sets for a similar output. The method of modulation adopted for the long-wave transmitter, known as ¿series modulation, ¿ and the design of the aerial compensating network and harmonic filter used for the long-wave transmitter, are considered at some length. The remote-control switchgear necessary for operating high-power transmitters from a central point is also dealt with. Part IV gives an account of the general performance of the station so far as it has been ascertained during preliminary tests and early transmissions for reception by the public.