Heathkit IT -3120 User Manual

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Figure 15
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Figure 16
GATE 1 AND GATE 2
The "Gate 1" circuit is similar to the Gm circuit. See Figure
14. However,
the Gate 1 test places a reverse bias on the gate
of
the F ET through resistor R9. Th is causes the channel of
the F ET to become electrically narrower, increasing its
resistance, decreasing its Gm. A noticeable decrease
in Gm
should be
apparent when the Gate 1 switch is pressed.
If the F ET is a dual gate device, the Gate 2 switch will
reverse bias
the second gate. A noticeable decrease in Gm
should also be apparent when the Gate 2 switch is pressed .
Igss AND Idss
Leakage currents are measured by placing a battery and the
meter (and ,its shunt resistance) in series with two of the
FET leads. The meter indicates leakage current from 0 to 1
ampere, depending
on the cu rrent range selected. Since the
leakage currents are quite small, usually measured in
microamperes (riA), the FET must be removed from the
circuit.
19ss is the measurement of the current that flows between
the gate and the source of the F ET with the drain connected
to the source. See Figure 15 .
1dss
is the measurement of the current that flows between
the dra in and the source of the FET with the gate connected
to the source. See Figure 16.

Heathkit IT -3120 Specifications

General

Brand	Heathkit
Model	IT -3120
Category	Test Equipment
Language	English