7.
The plate characteristic curve shown in part B of figure 4-1
illustrates how plate current varies with plate voltage.
In the
region between points 3 and 4, both plate current and screen current
are changed by a change in plate voltage; that is, an increase in
plate voltage will cause
a.
a decrease in plate current and a decrease in screen current.
b.
a decrease
in
plate
current
and
an
increase
in
screen
current.
c.
an increase
in
plate
current
and
a
decrease
in
screen
current.
d.
an increase
in
plate
current
and
an
increase
in
screen
current.
8.
The plate characteristics of a tetrode are said to have a region
of negative resistance or a region in which a decrease in plate
voltage will cause an increase in plate current or vice versa. This
region is noted on the characteristic of part B (fig. 4-1) between
points
a.
1 and 2.
c.
2 and 4.
b.
2 and 3.
d.
3 and 4.
9.
Negative resistance effects are greatly
reduced
in
modern
tetrode tubes. This has been accomplished by
a.
improvements in plate material.
b.
use of isolating top cap connections.
c.
nonuniform design of the control grid.
d.
overlapping design of the grids within the tube.
10. The purpose of the suppressor grid in a pentode is to suppress
the effects of
a.
secondary emission.
b.
high plate resistance.
c.
plate-current saturation.
d.
cathode-to-plate capacitance.
161
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