My speciality. Овчинникова Т.Е - 13 стр.

                     CHARACTERISTIC CURVES OF TRIODES

1. The effect of grid and plate potentials on flow of plate current can be investigated
by means of the circuit of Figure3. In this set up, if the plate potential Eb is held
constant and the grid potential varied, one of the curves of Figure 4 is obtained. The
other curves are found in the same way, by using different values of Eh. Such a set of
curves, showing the relationship between the plate current and the grid potential for
constant values of plate voltage, is known as the family of mutual characteristics of
the tube. By use of this family, interpolating between curves where necessary, it is
possible to find the plate current corresponding to any combination of grid and plate
potentials.
2. The effect of temperature saturation is not apparent. The reason for the absence
of saturation is that in most modern tubes the cathode is capable of furnishing many
more electrons than are required for rated current. As a result, a certain amount of
variation in filament or heater voltage can be tolerated without seriously impairing
the tube performance, and the useful cathode life is increased. It will also be noted
that the curves tend to be nearly straight lines in the upper portions, and that the
curves for various plate potentials are nearly parallel. It will be shown later these
properties are important where the tube is to be used as an amplifier, and where it
is desirable to keep the distortion of the amplified signal as small as possible.
3. Another way of presenting the same information is shown in Figure 5. Here the
grid potential is held constant for each curve, and the plate potential is permitted
to vary. This set of curves is known as the family of plate characteristics, and for
many purposes it is more useful than the mutual characteristics. The effect of
increasing the negative grid potential is chiefly to shift the curves toward the
right on the diagram, without causing much change in form.




Figure 3-Circuit for Obtain-       Figure 4-Mutual Charac-
ing Triode Characteristics         teristics of 6Z5 Triode




Figure 5-Plate Characteristics of 6Z5 Triode