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BELL SYSTEM TECHNICAL JOURNAL 



Fig. 19 — A positive grid oscillator designed for the frequency range from vSOO to 



550 megacycles. 



power law, that is 



K. 



P 3/2 

 da 



(2) 



so that the grid power will increase as the fourth power of the grid 

 diameter while the grid area and hence the heat dissipating ability 

 only increases as the first power of the diameter. Because of this an 

 upper limit in output exists, fixed by the maximum permissible heat 

 dissipation per unit area for the grid structure. The optimum grid 

 diameter will vary directly with the wave-length for which the tube 

 is designed, and if the ratio of the grid length to its diameter is main- 



