Transconductance as a Criterion of Electron Tube Performance

evaluation of electron tube performance has assumed QUANTITATIVE and control.increasing extension the electronicsselection added importance with the of into the fields of measurement Simplification of process of By T. SLONCZEWSKI of suitable tube types and operating conditions from the general data available is of considerable value to all engineers concerned with electronics circuit design. The conventional procedure involves analysis of the plate current-grid voltage characteristics. The simpler method presented herein supplies the same information from an analysis of the transconductance-grid voltage characteristics. These are usually supplied by the manufacturer or can be obtained readily by measurement . The method presented herein has been employed successfully for a number of years in the development of electronic measuring apparatus by a group of engineers who attended lectures on the subject given by the author. It applies chiefly to pentodes, where the internal plate impedance is high with respect to the load impedance. Its merit resides in the comparative brevity of the formulae, the ease of computation and the facility in obtaining the data from which the computations are made. It allows one to form a preliminary judgment of the performance of a tube from a brief glance at the characteristics furnished by the manufacturer better and faster than any other method known to the author. It should prove of value to the instructor teaching electron tube theory. In the interest of simplicity some of the subscripts m, p, c and g appended usually to symbols for transconductance, plate current and grid voltages are deleted below.