6—4.
VOLTAGE AMPLIFICATION CONSTANT ;;
119
changes (10 to 1) is known as the amplication constant of the
tube.
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6—4.
The Voltage Amplication Constant p….—The voltage
amplication constant or magnication factor ,u of a vacuum tube
is the ratio of the change of plate voltage AE,, to the change in grid
voltage AE,; for zero change in the plate current, (M,, = O). Thus,
in absolute value
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u =
—î%; , (I,, = constant).
(6—3)
The amplication constant ranges from 1 to 100 for the various
commercial triodes.
From equation 6—3 it is seen that a voltage
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AE,, applied to the grid may be replaced by an equivalent Change
volts in the plate battery.
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The amplication constant may be obtained from charaCteristic curves, as in the preceding section, or it may be measured
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directly by means of the Miller 3 balance method of gure 6—6. An
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FIG. 6—6.
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