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
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-
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I
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7:
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6
t
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4-4
1
Screen Potential (Volts)
--
:1:
--
--V
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F:
-.
I:
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--
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4
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4
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Correction
..... ..... ........... ....
Potential
Control Grid Potential
T
l
0
1
-(
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Lr
.
-
7 7
.......
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.
--
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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
-
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43
---
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r
'7
gw
I
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1
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e,
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,
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
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., -
t_
1, I
?
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I
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r
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j~T' 1 1I~~74 LI
I~7l- -I-i
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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
-
-
--
.
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.
t
-
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4:4-
,~
-4
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-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-
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4
4
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+ +.14
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P
1
T
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1
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I I I
t~
-- ' Z7
1;41
j
It l I
I
I
i
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I
I
CONSTANT CURRENT CHARACTERISTIC3 FOR PENTODE (6SK7)
WITH CONTRCL GRID HELD CONSTANT AT -8 VOLTS
-7---
-
i
F
S
-
-
-
--
-
- -
+
-
0
!
t-~-
--
-
-
f
~
1
-
-
-
-
-
--
-
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-
---
ti
It t
14- Screen Potential (Volts)
;-V-
rI
PLATE/YO.IL
t
-
5/f7
-.
-
PENOp
Functions of
I.
-
.
vs.
-
. . .. . ...
-
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I
---
----
----
~-
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-
tr*
--
-
00
}
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PL47E N#Q. XZ
-
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-
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
..
-
-
-
-
-
--
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L
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-,
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=7
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Division Factors
vs. LI)
GSKI1 Peuvoi~e
(FS(Lt) and F.p(L)
I :i:f~.
.i4~hf~>j&4..~/
v
2:272.1
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Grid and Screen Plane
.
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15 ii::.
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f:*
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22 ;:
2.
PL,~rt
IVT
PLATT. No,
NO, 73
:1
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!iiL-
4
i
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F~TF~FJ4
t
:77 -FT:
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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
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4
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Control Irid Potent ial (Volts)
-
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PLATS No.rr
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. ..
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L as
aa Function
of e
e., and e
a
Sp 7OFEA0E
+. . . . . .
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+
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p as a function of e,
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0
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LI.
1
c17-t11
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Plate Current vs. Plate PotenLial
..
...
r~~.
-l
.~L
U
-
--
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,.
4
1-
4 ~
-
i.-77 '
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Th~~1
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h
IL.
----
zxperimental Results
Method "A"
Method "B"
.
~4i77I7
Li
-
-
+
-
+
-A:
--+ .
-Arr-T
....
-. ....
-
*
- -.
j.
I
. -
-.1.
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4.
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1
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T
1 10
Screen Potential
L11F
p
---
e- Plete Potentia l
'-1--i
i
_____________________
:---
1mh
-
T
-- --
::: -
(Volts)
S
YY
--
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lit
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9
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t
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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
-!-
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21
Experimen tal Results
T-:..;
Method "E
.
4-...
I::::
-
+
I
_
I
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+ +
_
__________
___________
- +--- .
______
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.
~-
4
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4
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I
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_______
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m
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....
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ALL
e -Fla te Potential (Volts)
I.
I.
K
1~,
I
H-7-~K-j.
PATE Na*.W
y
1
TMIS
K~u
-
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let
-9
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S..,4
--- r---r
*
V
-
.
<~
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~se', PewTo~g
Cathcdc Currer.t. vs. PVte Potcnc1~
Screen Pot~r~t1:1 u 100 Vo1t~
I.
:~
.
.
9
K
t.
.,~.4
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