THE WORLD'S ADVANCE 



127 



former; this means (usually) a lower 

 power factor. 



A gap constructed on this plan is es- 



age required to bridge the whole gap cir- 

 cuit is employed. This voltage must be 

 high enough, of course, to give a smooth 



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7 



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Cuft vet-- 



Fig. 6. Diagrammatic Representation of the Characteristics of the New Spark Gap. 



pecially advantageous when high powers 

 are to be used in connection with small 

 antennae. The production of a given an- 

 tenna current depends on the equivalent 

 resistance of the antenna, its electrosta- 

 tic capacity and the potential to which it 

 is charged. A small antenna must be 

 charged to high potential for larger en- 

 ergy storage, and this means high spark 

 potentials. Then, with single wave radi- 

 ation and high efficiency at the coupling 

 coil, it is necessary to employ a spark gap 

 having impact excitation characteristics. 

 The gap described shows this property, 

 provided that the individual gaps are 

 kept very short, and that minimum volt- 



spark tone. On low frequency supply 

 the spark voltage varies throughout the 

 cycle and it is not sufficient to use a volt- 

 age which breaks down the gaps only 

 near the peak of the wave. It has been 

 found that condenser capacity and spark 

 frequency are important factors in con- 

 trolling the spark potential, and when the 

 latter is invariable at the transformer, 

 recourse may be successfully had to its 

 automatic adjustment by varying either 

 the capacity of the condenser or the rate 

 of sparking. A certain adjustment can 

 be found at which the manifestations of 

 impact excitation are most pronounced 

 and it is usually found most advanta- 



