Figure 3-2.
A circuit for a transconductance test.
3-6.
EMISSION TEST
An emission test is generally made by a circuit of the form
shown in figure 3-3 below. Rated filament voltage is utilized and a
reasonable value of voltage is applied to the plate electrode.
The
milliammeter indicates whether the cathode is emitting properly. The
various remaining electrodes (control grid, screen grid, etc.) are,
by means of switches, attached to the plate, one at a time. Failure
of the current to increase when a given electrode is connected is an
indication that that particular electrode is open-circuited.
3-7.
SHORT TESTS
Occasionally a short circuit develops between electrodes in a
tube.
A test for this condition consists merely in applying a
voltage across the two suspected electrodes. A device to
Figure 3-3.
A circuit for an emission test.
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