. The Bell System technical journal . _^ ) / / ^ — — -6 ^ I. / 11 / / x^ y^ v /^ / 10 08 2 07 5 .-to^D 2 Z _l iij •^ \ VOLTS Es= 90 VOLTS V --__ ^„ \ v 0 \l — 6. 0 20 40 60 80 160 180 200 220 240 100 120 140PLATE VOLTS, Ep Fig. 3—Characteristics of a screen-grid tetrode similar to those shown in Fig. 2except that E, = 90 volts. and its analogy with the generator equation, it may be seen that,despite the fact that the screen-grid tube considered as a generator hasa very high internal resistance, it gives normal output because it isprovided also with a very large electromotive force, From
. The Bell System technical journal . _^ ) / / ^ — — -6 ^ I. / 11 / / x^ y^ v /^ / 10 08 2 07 5 .-to^D 2 Z _l iij •^ \ VOLTS Es= 90 VOLTS V --__ ^„ \ v 0 \l — 6. 0 20 40 60 80 160 180 200 220 240 100 120 140PLATE VOLTS, Ep Fig. 3—Characteristics of a screen-grid tetrode similar to those shown in Fig. 2except that E, = 90 volts. and its analogy with the generator equation, it may be seen that,despite the fact that the screen-grid tube considered as a generator hasa very high internal resistance, it gives normal output because it isprovided also with a very large electromotive force, From this analysis of the characteristics of the screen-grid tube, 58 BELL SYSTEM TECHNICAL JOURNAL based upon the simple theory of triodes, one would expect that familiesof characteristics corresponding very closely with those of ordinarytriodes would be obtained if the total space current, or the plate current,. ^ y r ^135L-180 VOL s ^ y^ .TS •^ ^ ^^ > f^ ^ ^ ^ ^^ ^ -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 +1 +2 CONTROL GRID VOLTS, Eq Fig. 4—Characteristics of a screen-grid tetrode. Plate current, 7p, screen cur-rent, /„ and total space current, /,, as functions of the control-grid voltage, withvarious values of i)late voltage antl screen voltage as jiarameters. were plotted as functions of the control-grid voltage and screen-gridvoltage, with the plate maintained at any fixed potential higher thanthe screen potential. It would be expected further that the family ofcurves showing total space current would remain practically invariant THEORY OF MULTI-ELECTRODE VACUUM TUBES 59 with variations in plate voltage. The plate-current family of charac-teristics should show only small variations with plate voltage (so longas Ep is higher than £«)> depending on the magnitude of the change inthe ratio of I„ to h- Families of such characteristics
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
