IIYPEK-fREQUENCY \\A\'E GUIDES 



301 



GALVANOMETER 



TURRET CONTAINING 

 CRYSTAL DETECTOR 



(A) 



Fig. 11 — A tunable chamber resonant to short electric waves. 



In its role as a tuned circuit, the resonant chamber is sometimes 

 used as a wave -meter, sometimes in connection with a generator of 

 short waves (thereby enabUng a vacum tube to work more effectively) 

 and sometimes as an element in a receiver (thereby impressing on a 

 detector a maximum of the received wave power). When such a 

 chamber is excited by very short electric waves and is varied in length, 

 resonance takes place at certain specified intervals depending on the 

 frequency and phase velocity. This condition may be detected either 

 by a crystal detector and meter located just outside of the iris opening 

 or by a somewhat more elaborate arrangement whereby a crystal 



