SPACE CURRENT DIVISION IN SMALL PENTODES BY JAMES DARR, JR. and SOLOMON MANBER 1948 SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF BACHELOR OF SCIENCE From the MASSACHUSETTS INSTITUTE OF TECHNOLOGY 1948 Signatures of Authors Signature of Professor in Charge of Thesis 6'g '6 ii ACKNOWLEDGEMENT The authors wish to express their appreciation to Professor Godfrey T. Coate for his assistance in clarifying the problem and for his suggestions of possible methods for its solution. TABLE OF CONTENTS Page Title Page - - - - - - - - - - - - - - - - - Acknowledgement - - - - - - - - - - - - - - -11 Table of Contents - - - - - - - - - - - - - -11 Summary - - - - - - - - - - - - - - - - - - -1 Introduction - - - - - - - - - - - - - - - - - 2 Theoretical Discussion- 3 - --------- Division of the Space Current at the Control Grid - - - - - - - - - - - Division of Space Current at the Screen Grid- - - -------- Presentation of Results - - - - - - - - - - - 4 10 16 Conclusion - - - - - - - - - - - - - - - - - - 19 Plates I through XXII - - - - - - - - - - - - 21 SUMMARY It was the purpose of the experimenters to attempt to produce the static characteristicsfor small pentodes by developing functions of space current division at the electrodes. When operating pentodes within the normal range of electrode voltages, changes in plate potential affect the total space current and its division between the screen and control grid very little. Moreover, although the total space cur- rent is controlled largely by the control grid, the division of the space current between the screen and the plate is affected very little by the control grid potential. Taking into account the effects of initial velocities and contact potentials, and making use of the above facts, it is possible to express the electrode currents in terms of the three-halves power of a corrected electrode potential and an empirical function. Methods for obtaining the electrode correction voltages and the empirical functions for pentodes will be presented in this paper. INTRODUCTION The need for elaborate and costly equipment to determine the complete static characteristics of power triodes motivated E. L. Chaffee1 to investigate the division of space current in power triodes. From the results of his investigation, he was able to determine those portions of the static curves in the regions in which the maximum dissipations of the tube would normally be exceeded using ordinary direct current methods. By an extension of Chaffee's methods, Clifford M. Wallis 2 developed a method for determining the space current division in the power tetrode. It is the purpose of this paper to describe a process of further extending Chaffee's and Wallis' method for the determination of space current division between the electrodes of small pentodes. Since, for small pentodes, it is possible to determine static characteristics by direct current measurements, the results of this paper are of academic interest only. It is highly probable, how- ever, that this method in its entirety can be applied to large power pentodes where it would be of practical importance. 1 Chaffee, E. L. "The Characteristic Curves of a Triode." Proceedings of the I.R.E., Volume 30, Number 8 (August, 1942T~ 383-395. THEORETICAL DISCUSSION In Langmuir and Compton's3 paper, it was shown that Child's 3/2 power law (see Figure 1) should be modified by a correction voltage to account for initial electron velocities and contact potential. Ifthen, we write Child's Equation as i = A(V + Vt) 3 /2 , (see Figure 2) (1) the current at every point within a vacuum tube is Fi o.i. F .2. V * V+V AVV Y+V CI C, ___ represented, provided (V + Vt) everywhere is altered proportionately. If (V t Vt) in all space within a vacuum tube is changed by a constant factor (G), the current at all electrodes will be changed by (G)3/2 Considering the space just outside the cathode as the plane from which V is measured, the following 2 Wallis, Clifford M. "Space Current Division in the Power Tetrode." Proceedings of the I.R.E., Vol. 35, Number 4 (April, 1947)369-377. 3Langmuir, Irving and Compton, K.T. "Electrical Discharges in Gases." Reviews .of Modern Physics, Volume 3 (April, 1931) 237-257. 4. equations must apply in order to change (V + Vt) by a factor (G) at all points: = (a) e ' + c ~g + Vt (b) es' + c + Vt = G(e (c) esu'+ (d) ep' + f -0 c $su+ Vt G(eg + + #c = G(esu+ $c Op + Vt: G(ep+ -c * Vt) - + - Vt) su+ Vt) c - qp+ Vt) The O's in the above equations are used to represent the electron affinities of the electrode materials, and the potentials marked (') are the measured electrode potentials corresponding to the conditions that V' + Vt G(V + Vt). In the remainder of this paper, #c will be represented byA eg, 0c #c ~Bu + Vt byA esu, and Oc - -s ~ g + Vt + Vt byAe, p + Vt byA ep. In order to change (V + Vt) by a factor (G) at all points in space within the tube, (e.g -A e ), (e. -Aes), (esu -Aesu) and (ep -Ae) must each be changed so that their ratios remain constant. Division of the Space Current at the Control Grid As can be seen in Figures 3 and 4, variations of the plate potentials of pentodes.over a large range has little or no effect upon the potential distribution between the screen and cathode, and hence has little effect on the total space current. Until the plate potential becomes so low that the effective potential 5. at the suppressor .rid plane becomes negative, the plate voltage has little effect on the total space current or its division between the screen and conWhen the plate potential is lowered to trol grids. P, FIG. 3 $ C such a point, some of the electrons approaching the suppressor will lose all their forward velocity, and will be attracted back towards the screen. Part of this electron flow will pass through the screen and continue on towards the cathode, which effectively reduces the total space current and alters its division between the screen and control grids. The curves of the current ratio (ig/io) versus plate potential on Plate I, plotted from experimental data on a 6SK7 pentode (used throughout .the experiment), show little change in division ratio for variations in plate voltage over a large range. Since the current density and potential distribution in the region between the cathode and screen grid are not materially changed by changes in plate potential, it is necessary only to satisfy equations 6. 2 (a) and 2 (b) in order to change V + Vt at all points in the grid-cathode region by some factor (G), If we are to satisfy these equations, (eg -e ) and (e. -A es) must be changed in such a manner that their ratio remains constant. If we call this ratio L., then (3) L S = ege- es -Aes .Q eso The curves of constant isp (plate plus screen current) and constant io (cathode current) in the esp-eg plane (see Plate II) are analogous to the constant i9 and i plane. curves of a triode in the ep-eg Over a large region, these curves are parallel and straight, and may be written in terms of the corrected grid and screen voltages as follows: (4) 10 ' = B (eg -Aeg) (es -6 e,) 3/2 + L /flgs B ego + es, 3/2 B !s]3/2 (1 1.4 gsLg] 3/2 where B is the perveance of the tube and/gs -'be he 9anddes may be determined easily from the constant 1o curves on Plate II as follows: constanat "~* 7. i (5) = B e.i -A e + (e.i -Aes) 3/2 12 = B eg2 -& e g + (e.2 -Aes 3/2 13 = B e 3/2 -A eg + (e.3 -es 3 For constant measured values of i, unknown,/4t, 12, and i, the may be determined from the slope in the linear region. This leaves only B, Ae, unknowns in equations (5). andAes as By simultaneous solution of the three equations, these constants may be determined. Another method, which checks the one outlined above very closely, may be used. This method was used by Chaffee and Wallis in the case of triodes and tetrodes, and is illustrated on Plate II. the ratio (ego/eso) = L If is held constant, the ratio of currents, (ig/isp) will also be constant. There- fore, if several points are obtained on the esp-eg plane for a constant value of ig/isg, these points (Pi, P2, P3, and P4 ) will lie on a constant L These constant L line. lines are straight and all pass through the pointa e andAes. Hence the intersection of the lines determined by the constant ratios of ig/i sp will be the pointA e andAes, and can be measured directly on the esg-e on Plate II. plane, as can be seen 8. Analytically, this may be shown by the follow- ing formulae: (6) isp2/ispl = [e 2 -esi3/2 esl Aes - or i sp2/J spl = [e.2 eg - Ae from which (7) e = egl(isp2 /ispl 2/3 ~ eg2 (isp2/ispl) 2 /3 e esl(isp2/ispl)2/3 1 - - s2 (1sp2/ispl) / where the subscripts (1) refer to the point P1 and the subscripts (2) refer to the point P2 on Plate II. The equations above were solved for all of the points on Plate II, and their values averaged. values of Ae The average and des found by this method agreed quite -well with the values found by the other two methods. At low values of screen potential, the curves of i0 on Plate II can be seen to vary from linearity, and this departure may be treated as an empirical 9. function of Lg. Equation (4) then becomes = B eso3/2 [1 (8) +/AgsLg3/2 * F(Lg) es j In similar manner, recalling that the current division at the control-grid is independent of the plate voltage, we may define Fg(L ) and F sp(L ) as the current division factors operating on the "linear" cathode current to produce the actual i. and isp. The following equations may now be written: (10) isp = B es 3/2 l +/4ggLg]3/2 Fp(Lg) )"gsJ 1 (11) = B e 3/2[l +/4gsLg]3/2 * Fg(Lg) 9so F (L,) = F(L)- F (12) The curves of constant i, (L isp, and i are plotted on Plate III from experimental data, and constant L origin. lines are plotted from the corrected From the above definitions of F(Lg), Fsp(Lg), and Fg(Lg), and the notations on Plate III, it follows that (13) F(Lg) = 0(e e e) (14) F ,(L (15) Fg(Lg) ) (esoV/esoV)3/2 = (esoIV/eo VI)3/2 would be true if the curves on Plate III represented equal values of current. However, it was thought best to limit the grid current to a small value. It is therefore necessary to divide equation (15) by the ratio of io to ig, which is 7.5. DivisionVof Space Current at the Screen Grid Although the total space current is largely determined by the control grid potential, the'division of this current between the screen and the plate is nearly independent of the control grid potential over the usual operating range. Experimental veri- fication of the-above statement is illustrated on Plate IV. As can be seen from Plate V, the constant i0 and constant 10 (since e. was negative, iE was zero and i0, isp) curves were straight and very nearly parallel to the plate potential axis. In this region, for any constant value of control grid potential, isp could be described by isp = C eso+ (16) e 3/2 4sp when esu is held at cathode potential (as was the case throughout the experimental work) andAesu is assumed to be negligible. eso' In the above equation, and epo' are the electrode potentials necessary to cause the same cathode, plate, and screen current if the grid were removed, and/4 p Is the slope of the constant isp curves in the ep-es plane. Since these curves are nearly parallel to the plate potential axis,/dsp is very large. Equation (16) may also be written as 1s (16a) where Lp = - C' e sps + L . 3/2 - 3/2 epo'/eso * Since e50 ' = es ~es' and epo' is necessary to determine &es' andte P' ep - A.ep', it in order to locate the potential origin on the ep-es plane from which the 3/2 law is applicable. Sincei,,p is large, isp is practically independent of epo' when eso' is appreciable as can be seen from equation (16). Solving equation (4) and equation (16) simultaneously will show the dependence ofA es' on the control grid voltage, e . 12. =B (4) (4a) 10 (16) isp -ego + e 3 B (e io C 3/2 + es -A es)3/2 + epo' 3/2 eso ,sp mn (16a) 10 isp where E : e 0 C(e - e 3/2 + E) 3 /pup and is small Therefore, -Ae.' + E = eg 0s ~e. And e.' Ae.' where k, :Ae5 constant. = (aes + E + Aegpgs) = k + ~/Mgseg - 'gseg E + Aeg/gs and is approximately a Therefore, to a first approximation, Aes' varies linearly with e . Again, there are several methods of determining Aes'. It may be determined analytically by use of equation (16), as shown immediately below, for any constant value of control grid voltage. ispl C esl -Aes' + egol 3/2 L spj isp 2 = C es2 -Aes' Holding epo constant, epo 0 epoi/4sp (18) = E, which is &es' = es2 tpo2 epo2, and letting small, esl(ipl/ip 2 )3/2 - 1 - (ip1 /ip2 3/2 Since E is small compared to the first term in equation (18), it may be neglected for all practical purposes. Aes' was calculated by equation (18) for a number of control grid voltages, and the results plotted as curve "A" on Plate VII. Ae p' and Aes' were also determined by the method outlined by Wallis in his article on tetrodes, which is similar to the method for determination of the correction voltages for the control grid and the screen grid as outlined previously. This consists of deter- mining a series of points in the ep - es plane for each of several constant ratios of 19 to is. By locating the intersection of the lines drawn through each series of points, the origin on the ep-es plane from which the 3/2 law is applicable is established. These correction voltages may also be determined from the above points by analytical methods as shown below: (19) Aep' = egoi(ip 2 /ipl) 2 /3 - epo2 (ip2/ipl)2/3 . 1 (20) &e.' eSol (ip 2 /ipl) 2 /3 (ip2 /i 9 2 /3 - eso2 -1 where the subscripts (1) refer to P1 and subscripts (2) refer to P2 on Plates VIII, IX, X, and XI. Since the constant ip and constant is curves are nearly vertical in the ep-es plane in the usual operating range of plate potentials (see Plate V), it was impossible to locate points of constant ip/is with any accuracy in this region. For this reason, it was necessary to locate these points of constant ratio in the region of low plate potentials where the plate current is largely controlled by the plate voltage. At these plate voltages, the field at the suppressor grid becomes negative, causing electrons to return towards the screen and cathode which reduces the t6tal space current. Because the correction voltages must correct for space current, any screen correction voltage experimentally determined at low values of e would not be expected to agree in mag- nitude with values obtained at high plate potentials. The correction factors determined at these low plate potentials is Curve "B". also plotted on Plate VII, labeled 15. Nothing has been said as yet about ,ep plate correction voltage. , the While this was impossible to measure at high values of plate voltage, it will be shown later to be neglijgible in this region. In the region of low plate voltage where it was measured (described above), this correction voltage was found to be very small, and hence unimportant. Plate VI shows the constant i and constant 19 curves on the ep-eg plane in the region in which they depart from linearity. Here the total space and electrode currents may be expressed in terms of the "linear" space current and empirically determined functions of Lp by the following equations: (21) -1 +3 t isp .Ce 0sj .p (22) ip is J :'] C L 3/2 1 + Ce ,sp (23) 3/2 -F(Lp) LNp -Fsp] F(Lp) Lp j- 3/2[l + . 13/2 -F(Lp) LP1 As can be seen from the above equations, along a line of constant Lp, 3/2 power of ey0o1 . it follows that isp, ip, and is vary as the Using the notation on Plate VI, 16. (24) e-0 13/2 F(Lp) e =epo2 3/2 e[polj (25) Fy(Lp) (26) Fs(L): F(Lp) - Fy(LP) From the foregoing equations and the data on Plate VI, the functions F(Lp), Fp(Lp) and F.(Lp) were plotted on-Plate XII. Since Lp = epo'/eo' , for high values of epo, Lp is at least greater than unity. As can be seen from Plate XII, for Lp greater than one, F(Lp) and F (L p) are'very nearly constant. Hence, the value of dep' at high values of e has no effect on i, or its division between the electrodes. Since, as previously stated, Aep was found to be negligible for low plate voltages, it may now be disregarded over the whole range of ep. PRESENTATION OF RESULTS For a given control grid potential and a given screen grid potential, Plate XIII may be used to determine the "linear" cathode current. This, in reality, is a graphical solution of equation (4) 17. which may be written in the form (4) i3 = B e3e + e. -aes }4gs This solution is accomplished by plotting io' 2/3 on the ordinate against e on the abscissa, holding Agsego equal to zero. The value of/4gsego is plotted versus e so that the vertical displacement from the abscissa equals the e 0 value. This distance, determined by e., is then added to the es value by a 45 degree projection. Plotting io' versus i 2/3 on the same plate allows the "linear"o cathode current to be read directly. It is necessary to correct the cathode current by F(Ls) for both positive and negative values of L . On Plate XIV, lines of constant -L are drawn, and from the screen and grid potentials, it is possible, by interpolation, to determine -L important range. over the The correction factor F(-L ) is plotted on this plate also, and when the io' from Plate XIII is multiplied by F(-LE), the actual 1o (in this region i= isp) is determined. The same procedure is followed on Plates XV and XVI for positive L values. On Plate XVII, the experimental and calculated grid current for a screen voltage of 50 volts and a 18. plate voltage of 50 volts are plotted. The data for the calculated curve was obtained by multiplying the cathode current i0 from Plate XIII by the factor F (L ) obtained from Plate XVI. These curves are very nearly parallel over the entire range of grid voltages. However, the theoretical curve shows slightly higher values of grid current than the experimental curve for the same grid voltage. It was found that increasing the screen voltage increased the total space current, but decreased the control grid division factor in such a manner as to offset the increase in total space current, so that the control grid current remained essentially constant over a wide range of screen voltages. In this respect, the theoretical curve showed the same properties' as the experimental curve. To determine the division factors F(Lp), Fy(Lp), and F5 (Lp), it is necessary to determine L'p, which is dependent upon grid potential, screen potential, and plate potential. The dependency upon grid potential results from the fact that the screen correction voltage is a function of the grid voltage. On Plate XVIII, this correction voltage is plotted versus grid potential (taken from curve "A", Plate VI) in such a manner that the screen correction is equal to the distance from the ordinate. By means of projections, 19. this correction voltage is subtracted from the screen potential and L = may be determined (since ep epo). Plate XIX is the same as Plate XVIII with the exception that the screen correction voltage curve "B" on Plate -VI was used instead of curve "A". Although curve "A" is assumed to be the better curve, as a check, each was used in determination of the final results. On Plates XX, XXI, and XXII, the experimentally determined curves of plate current, screen current, and cathode current are plotted along with the calculated curves. The two sets of.calculated curves resultsfrom the use of curve A and curve B on Plate VI in determining Lp. In many places, the two curves overlapped, and at no point was there any large discrepancy. Both calculated curves predicted the knee of the curves and the magnitude of the currents as close, or closer, than the experimental curves of other 6SK7 pentodes. CONCLUSION The data used in this paper was compiled entirely from experiments on a single 63K7 pentode. This tube was carefully selected to insure that its characteristics were typical of its class and the tube free of gas. While the results of this 20. experiment are not conclusive because the investigation was confined to a single tube, it is strongly felt by the experimenters, because of the positive results obtained, that the application of this method is not limited to this pentode alone. This, of course, would bear further investigation. The presentation of empirical functions can be simplified greatly by plotting them on a log-log chart in a manner that allows complete static curves to be obtained for any grid, screen, or plate voltage within the normal operating regions. Such a method is outlined by Chaffee and Wallis in their articles on triodes and tetrodes. ~FTT~7. ~1 Curves Showing the Current Ratio (1 /1 ) As a Function of Plate Potential fo_ Several Values of Constant Grid Potential 6 S67 SCMN VLAGE: /00 V0-TS .1 :.. AhWrOAC 1 I= :71:71 1*~** L imam * I I :1 t. 717 Jjt 7I m1'9 p - Plate Potential PrATE /VO I volts) 7 A Pi TE/VO IT r wi 1........ 4, 7* . 4- . ~LN 7 P7 7 Qurves Con stant Current .. f.or pentode . .. ... Sol id lines -1 I .. .. ... Interrupted line -1 43F * I.... . ii' .214> In 1:V 7. :1 1 .3 .4 I-. 4-3 K -- U -4 r-4 - 1/ +1: A tA ~~1 1t I * 4~.. 4C s'N T '7 4-4-4. .1'.:: 7. 4. ik * .: 4 -7r r4 1 (V y At .7. 7i -i-i -fse a a i J' 14 - K' b *1 T -4. * 4 - -A IL I-I I - 1- 'I,, ..i~1Kii ET1 4~lTT Al.e jjJ~j+ - Control Grid Potential (Volts) 4' +4 LATE N0. iz 01 Cha racteristics C t (D 3X7) 0 0~ - -7 Cf) 4-- co _0 0 .,i1. PC2h1 ..... - . ~pie., - ~id~n.a. ........... e 4 I e - orrected Grid Potential (Vo lts) 7 :. a .. -77 I, :. p4 e I - rild Potential (Volts) [* T , -- - T-7. :1: 'I~1K; PLA TE NO1-~ 0 Curves Showing the Ratio of Plate Current to Cathode Current as a Function of Grid Potential V4 ______N7 PEN7moE 43 CO) U) ; + + 4-3 I* . 0 .. fe -SC,?eiM/riz41 IN es SC EEM MT4TN* . ... . 0 f 43 t K I -4 4 K *.... I I.t . e.-. K;:e Grid Potent.1 K I. (volts) t ,t J rATE AO. W 44-.J Const:t Current Characteri-ti c8 for Fe tode (6DIf7) KH 1 4' I I*L. I.', j 4 If I.. I I ii #-4 -d ii II tLIL 4 1~~~" C11. F 7jj7 .L. I:: -I 'I. '4 :1; 0 *I. *II I 77.. - 2 I ____ 1'7 77- r-4 - - - - . 4 . [ ii --1-i - I. 1.1 j~1t 4 4, I-t- 4.. 7, ,J .4 + :2 *: . ~-U -4 .. 4FT 17;. 1t :A. .41 2 vi- Iii7KI K1 77 7: ! wpm ' s 6 t t4 - .. - : , .1.. - K. 4-4 1 Screen Potential (Volts) -- :1: -- --V __I F: -. I: -F -- - ~44 4 1~~~~ I~- i-P- n4;0 t--t + ['2. 44 A: .1 tv'- 1ti -7 'r"' .1 I :1 If 4 m- -- 4 4 h11J21 4 t V444444tjJ !4 4 ------ . . 1~' i T j ...... ..... ..... 4 -*- Screen Grid -* 4 . Correction ..... ..... ........... .... Potential Control Grid Potential T l 0 1 -( 1----* I............... Lr . - 7 7 ....... (V -lts ------ - --.. . -- .- t.. 11 I --I -7 - TI Curves f or Determination of Screen and Plate "F" Factors w-. eg : -1. 8 volts 6'SK7 PENITODE 55f ... - 4 e- - - --.- 00 Scren 4 2 .. 67 i..d ..... r-41 4.4 4 4 89 5 * .4 0 I* 4.4 . Clo 6creen Gri d Potential (Volts) 9LdITE /YO 440 I I -T11- IA .F 4~.WITH CONTROL I I-LLI JJIJJJJHLLLhIILA r CURRENT CHARACTERISTICS FOR PENTODE -CONSTANT GRID HELD CCN3TA::T AT -2 VOLTS (65K7) flif I ~l-Th -K-N 43 0 __, -1 A - X-IK 43 --- K~~~ ~--- A~1 P4 r '7 gw I -1 1 _ 4~ - ~~ ---- r il e, - K~Th , Screen Potential (Volts) -T ATE O MY- t 1 I iiLIIHI~TN I~II*j~ J. NST'-NT CURRENT CHARACTERISTICS FOR PENTODE (65X7) TH CONTRCL GRID HELD CONSTANT AT -4 VOLTS 4 4 4 -1 ;4 4 1 F ! - i. i I !. i t + j,j-t 1 i I 1 _t M - ., - t_ 1, I ? . t I i-I I r F:, -T I -4 -1 --, - --- - I "44 -IT- ILL11, I , f, -IF' . aI.t. ? ~:i}~± i-i 4....iAt *r j~T' 1 1I~~74 LI I~7l- -I-i 1~ .J1,E J~ r j4ji~j-~t a- Screen Potential (Volta) PLATE NO. IX URNH~CTITC OE4OE(87 71 r I Ii 1411 111111111111 I I ~ 1'1 I ti74~5~ I I I LL I L~2t [' ~I-~ LIJ-1 1 . 4 j bae" CCNSTANT CURRENT CHARACTERISTICS FOR PENTODE (65K7) WITH CCNIRCL GRID HELD CONSTANT AT -6 VOLTS 7=T ~TT2FT~h11V7 I 1 %1 !_ 1 xI - i~~~~~~t - - -- . - . . t - T7 4:4- ,~ -4 +4~ -1 4_ LLLLLLLLLLLLLI~L4~4~~ e. - Screen Potential (Volts) I-- :- .~.1 iT1~.i ~I I TI I I P 4TE /YO X f-- 1- I I I -. f- -Ii I. t t I - -1 4 4 KIL + +.14 1-#I P 1 T *1 r-- 1 ~ I I I t~ -- ' Z7 1;41 j It l I I I i i I I CONSTANT CURRENT CHARACTERISTIC3 FOR PENTODE (6SK7) WITH CONTRCL GRID HELD CONSTANT AT -8 VOLTS -7--- - i F S - - - -- - - - + - 0 ! t-~- -- - - f ~ 1 - - - - - -- - -~t - --- ti It t 14- Screen Potential (Volts) ;-V- rI PLATE/YO.IL t - 5/f7 -. - PENOp Functions of I. - . vs. - . . .. . ... - - I --- ---- ---- ~- '-7 - tr* -- - 00 } -i L !f PL47E N#Q. XZ - - -- -- -l-- - Emissicn Current (ma) :h-critic $ D 28 W ED I.- / 8 65K7 - P6NTD06 Curves for D0etermination of 10' (10' as a Function of *i-1 e and e.) * r4"N 0 L I a o1ot 6ntiso e It 10 -6 -~ ' Scre e n Potential I -- e - Control Grlid Potential (Volts) AlATEe4 " --1 I - Constant -L Curves- r-4 0 r-4 -S'-4 63SK7 Pmv7WE vs. (-L)- F -Lg) ;.4 +30 L - : -L (~O 1... -. 4 Screen Grid Potential (Volts) . I 1 ~.. NO 4' I T * ...... I hZ/t f & /'vM .A4,rc - 77] 0 CtC O~- I -- -- ----- 0 C11 ...4- Screen Potential (Volts' . 4 .. - - - - - -- - L - 4- -, - L - I.* T- - 7* - :47 T. - -+ t 1- I I * - '112.1.1 4. I: . K ::~:. - - I+I- - ~7k~27 Ii 7i ~ .Ii~ =7 :2 i 2:: -~ ~-r - Division Factors vs. LI) GSKI1 Peuvoi~e (FS(Lt) and F.p(L) I :i:f~. .i4~hf~>j&4..~/ v 2:272.1 I Grid and Screen Plane . - 1~~.~ -~ * -~1-* tI - +t+ 4t: U. . . NAW .. . :2: yb-I ........ .1 .- . [2 . ... .. .2.;.. .. . . .. . 4.... * . -- -I - - tA/1zE1221 7 44 ...- -.. f t 7 ) 4 1. I~K 1 - -+- -j H - *" -- 4-4-t.. . . ...... ... . ..~ w .. .... P~:... .. [:22: 1: .... -4 -7 .1. ::.t: ~E~VI .1.. 1- ~T-5p7 *K :2Z 4.. .221::~:. .4.4-..,. .. .2t. -~ ~22. :::jA -- -~~~~~~~.. T4 T~ . .. . .. . .. . . .. . . _. 15 ii::. 3I 5'7 -4- - -----4.. .1 LI f:* f 22 ;: 2. PL,~rt IVT PLATT. No, NO, 73 :1 - -- - .. -.-.- !iiL- 4 i - F~TF~FJ4 t :77 -FT: -.. -- - 4 .. .. -- *4 - -. . -- - .. - 4t ~ ~ ... t- - Control Grid Current vas. Control Grid Potential 41 ---- FIrT0 a(ep a 50 volts) (es a 50 volts) 65/(7 - 0E 4 4 -- :2.7 7717 V 1<. 0 +4 .~ . 4 . ~ 1. Ii ,~LjTj K- 7i -7t j : :. -1 -i MW .<~d - ..... ......1K .4 74 --- i .2.24.7: -- - 77 -'' I.... ::[ 0 7. ~1 ____________ 0 T77tT +tR 4 . -.. -114A ...~.41.4 ~:. .. 1 . -+ - f. 4 e' MOE . .I do1- - - - -e - :2: -77. :1).. Control Irid Potent ial (Volts) - ill t t 4- -,. - --- :~7I - PLATS No.rr - - { - - - - - - I t* * *t ....... SAMTE NUVOX I 4... * Ji<:vii*:~ I I .i. . ..........,. . . . . .+ +.. . . .. . .4 . .,. . . +. . . . . , . . 4 . . .. . . . . . . . .. + + . ... . . 44 . . . . . . . - .t . . . . . . . . . . --- - , . . ' l . . . . 4 .. 4 . . 4 + . . . - . .. + ... . . . . . . + + . + + + . . . + . . . -- . . . ' . . 4 . +. . . . . . . . .... ... . . . + . . . + . - . . . . - + . + . .' . * + .. + 4 ++ 4 + i I + + . . * . 4 .. . + 4 .+. , . .. +. . - . - - ..... +. LI.. . . . . . + -...-+ + . . - . . - . - .-+ .+ . +. . . - . - . - . - - - -.. ' . .. . . am, g ..I..... | 1 F /.. 1'~ - - --7 1'*~ .. -I ------ - E I /LJJXJ .. -ia -+-/+-.1 '4 'K V: :2.44.:. 7/K I/v -4 / 7;t 44 . .n's bY if .]. .. . I ... . .V .. *1H>t K. ... A . .. ... p ... . .... .. .. ..- -4' i ~ I. .- ~..*.D Plate CI Potential (Volta) 4- .. e . . Vt-- ....- - L - - *'. .- ' 2 ..+-..F..F. + 0 . . . *.' -f -- L- .... ...- it . + . . .711-. -* -:- I -2-- . .I 4 ..* 43 .... . i 4I.T . ' --" . . . * -' . . . - . -+- - .4+....... . . . . -- . .. .. +Vt ++ . . .. . -.- e ,. 4 . . . . . . . '.- +LI 4 . . - - - .- .- +--------------- .. . . . . . . t+ .. . . . . . ----------------------------------.- . .. . L as aa Function of e e., and e a Sp 7OFEA0E +. . . . . . --Ie + IT4ATENO T/ p as a function of e, aa /7 PENoDE es, 'and e CL I, 4; C!' /I / 'I V / ~T4~ j'~ I I j 7 I. ~ -J 1~~ .. i >1' I. .~1. 'I / / iIf' P~. I-.. P. i* I I Ij ~1 I. I I Plate Potential (Volts) A-4 1) W43 *1 4 0 I *.1 ~~ - I, L~ 7-1 ~TT ,..... ..-. -- -- - -~ - - Itt;-- 77 - - ... 27.4.~ * --- -~7 - -- 7- :i77-- 20~~~7 * ~ L ~ ~ ...... LI. 1 c17-t11 -:T -: 1-- - Plate Current vs. Plate PotenLial .. ... r~~. -l .~L U - -- .... - -I .. ,. 4 1- 4 ~ - i.-77 ' - I 1~ 2! Th~~1 -. - h IL. ---- zxperimental Results Method "A" Method "B" . ~4i77I7 Li - - + - + -A: --+ . -Arr-T .... -. .... - * - -. j. I . - -.1. I...... 4. -4----, ~4.4..4. I. ~ ... I . . . E- _ Ti A 1 -- -.-.-.-.... - *-L -* -1--- fr. -L -7 -w L-:: I -4-. -- .. -. -.44A - ~ t T, Volt K.I.. 4 T 1 10 Screen Potential L11F p --- e- Plete Potentia l '-1--i i _____________________ :--- 1mh - T -- -- ::: - (Volts) S YY -- - -+-;-i *J - .1 77. .. ____ 14 J49.... .9 .9 lit .?... . 9 .1 ____________I } iTT t I~~.... - I 7=7 . .... I.- ENTODE 65/(7 acreen Grid Current vs. Plate Potenti al Screen Potential = 100 Volts 7.. A9- - .9- T.- " -T 7T j~9 4 .- ----- 7 -!- W4 - 0a -t - 21 Experimen tal Results T-:..; Method "E . 4-... I:::: - + I _ I __ + + _ __________ ___________ - +--- . ______ ______ . .. .. . .. . . . - . ~- 4 ~14~ -K-- 4 - - . . . . . . - y -. -Z* ,--I - :::..: . .. . --__- TpTrK< q - I I-.-... -. 9 - K'- _______ t ~T~ m Ois V .... '..180 ALL e -Fla te Potential (Volts) I. I. K 1~, I H-7-~K-j. PATE Na*.W y 1 TMIS K~u - .4 let -9 .I~.:.4~1:K2. S..,4 --- r---r * V - . <~ .4- ~se', PewTo~g Cathcdc Currer.t. vs. PVte Potcnc1~ Screen Pot~r~t1:1 u 100 Vo1t~ I. :~ . . 9 K t. .,~.4 __t< C" E IF . J-7---j r I -~ - 4, -~-~1~w. K;0 - ~. £4 _____ 1~ ____ ______ L ___ ___ ____ 1 ___ ___ 4.) 1 0 - -- ~ 1.7 9 , 0 __-1.*. ____~***~*~**~j.~ T -1 1- -4 4.-.. 4. . I 9 4. ~ , .1 £~xperiTent.a± ~etboc~ t~-~ 4. "A" ~ethcd "E" 17 LI 1~ 4 1~. ........ -, . ,~ .4 I.. t-t ::KV ~ * 1' PL A~ £. (V~1t~) I'll 11 , k(eSUit.8 . ~1av.1~ . .