. The Bell System technical journal . r cent in output power over that obtainable atthe customary operating point. Other considerations such as stabil-ity with battery voltage variations operate in repeater practice to fixthe grid potential at the customary values. There has been considerable discussion recently as to the maximumundistorted power obtainable from a tube with fixed plate potential,and variable load resistance and grid potentials. The above analysisshows that in the strict sense of the word, distortion (Co, Cz) alwaysexists, while with some arbitrary criterion of distortion, resu
. The Bell System technical journal . r cent in output power over that obtainable atthe customary operating point. Other considerations such as stabil-ity with battery voltage variations operate in repeater practice to fixthe grid potential at the customary values. There has been considerable discussion recently as to the maximumundistorted power obtainable from a tube with fixed plate potential,and variable load resistance and grid potentials. The above analysisshows that in the strict sense of the word, distortion (Co, Cz) alwaysexists, while with some arbitrary criterion of distortion, results mustdepend upon the specific criterion adopted. Now as to the maximumfundamental power obtainable, it may be shown that with a parabolictube characteristic the maximum is obtained for R = ^ Ro, Ec ^ - 458 BELL SYSTEM TECHNICAL JOURNAL These values are not very critical, however, since when we put R= Rq and Ec = — Eb/lix the power drops by about ten per last condition is that for maximum power at maximum gain,. -ZO -18 -16 -14 -IZ -10 -6 -6 -4 -2 VOLTS GRID POTENTIAL Fig. 10—Maximum power output as a function of the grid potential. EL tube ,150. Ep = 120, E = Ec, R = Ro in which the output power for a definite alternating grid potentialis maximum. In view of the fact that it approximates optimumconditions and is much more convenient as a basis for calculation,we shall use the maximum power—maximum gain criterion of theperformance of tubes. Current and Power preceding analysis has shown that the maximum powerobtainable at maximum gain without drawing grid current andwithout exceeding the negative end of the characteristic—at whichgrid potential variation produces substantially no plate currentvariation—is to be found at a grid voltage about midway betweenthe two voltages specified by these conditions. It is again instructiveto compare the predictions of the two theories as to the power dissi-pated in the tube, the power de
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