[Annals N. Y. Acad. Sci., Vol. XXVII, pp. 215-243. 2 August, 1917] 



OPERATING FEATUEES OF THE AUDip%*^^ ^^// 



By E. H. Aemstrong (^ SEP 1 3 1917 < 



CONTENTS ^5^^A,aL M useM^^> 



PART I ^^ '«Lm"» ^ 



Explanation of the Action of the Audion as an Amplifier and as 

 A Detector of High-frequency Oscillations 215 



PART II 



Some Recent Developments of the Audion Receiver 223 



Reenforcement of Radio Frequency Oscillations by the 



Audion 224 



Audio Frequency Amplification 228 



The Audion as a Generator and Beat Receiver 229 



Peculiar Features of Oscillation 231 



Audio Frequency Tuning '. 233 



Cascade Systems 235 



Effects of Atmospheric Disturbances 238 



SUMMARY 242 



PAET I 



Explanation OF the Action of the Audion as an Amplifiee and 

 AS A Detector op High-frequency Oscillations 



Although the audion has been in use for several years as an amplifier 

 and a detector of high-frequency oscillations, the explanations advanced, 

 to account for its action do not appear to be satisfactory. With the idea 

 of pointing out some features of operation which heretofore do not seem 

 to have been appreciated, the following explanation and oscillograms are 

 given. 



The audion is essentially an electron relay; that is, the exhaustion is 

 carried to such a point that the amount of gas present is exceedingly 

 small, and the current between the hot and cold electrodes is entirely 

 thermionic, the absence of gas making impossible the presence of posi- 

 tive ions. The operating characteristic of such a relay is shown ia Fig. 1. 

 This characteristic was obtained in the manner indicated in Fig. 2. The 



^ The material for the present article appeared in part in the Electrical World De- 

 cemher 12, 1914, and in part in the Proceedings of the Institute of Radio Engineers, 

 September, 1915. It has been combined, revised, and partly rewritten for the present 

 publication. 



(215) 



