TM 11-6625-539-15-2
(3) Set the function switch to DIODE 1-10, and
(7) Set the function switch to OHMS C-E.
adjust the CAL control for full scale meter deflection.
(4) Set the polarity switch to REV NPN, and
read the diode ratio (with a reference to 1) directly
on the BETA (top) scale.
(1) Set the polarity switch to correspond to the
i. Field Effect Transistors GM (Out-of Circuit).
type of semiconductor device being tested.
(1) If a field effect transistor with short leads
(2) Place the transistor in the socket on the lower
is being measured, place the transistor in the small
right corner of the front panel.
socket on the lower right side of the front panel.
(3) Set the function switch to ICO OUT/CKT
Place the drain lead in pin C, the gate lead in pin B
X1.
and the source lead in pin E. The transistor jacks on
(4) Read the ICO directly in microamperes on the
the front panel are spaced so that they will accept
center (ICO) scale.
(5) If the meter indicates in the high portion of
a standard test adapter for rapid testing of tran-
the scale, place the function switch in the ICO OUT/
sistors with long leads.
CKT X10 position.
(2) Set the polarity switch to FWD PNP when
(6) Multiply the ICO reading in microampere by
testing an N-type transistor, and to REV PNP when
10 to obtain the True ICO reading.
testing a P-type transistor.
f. Diodes in Circuit.
(3) Set the function switch to F.E.T. CAL,
(1) Set the polarity switch to FWD PNP.
and adjust the CAL control for full-scale meter
(2) Connect the cathode of the diode to the
deflection.
red lead of test the cable; connect the anode of the
(4) Set the function switch to F.E.T. READ,
diode to the yellow lead.
and read the GM of the transistor under test directly
(3) Set the function switch to CAL DIODE IN/
on the meter on the bottom (GM) scale.
CKT.
(4) Increase the CAL control until an upward
j. Fields Effect Transistors GM (In-Circuit).
deflection is visible on the meter. If an upward deflec-
(1) Insert the three test leads supplied with the
tion is obtained on the meter, the diode is neither open
instrument into the three color-coded jacks on the
nor shorted. If there is no deflection, the diode is
front panel, being careful to insert the red probe
either open or shorted or the circuit impedance is
into the red jack, the black probe into the black jack,
under 20 ohms.
and the yellow probe into the yellow jack. Connect
g. Diodes IR (Out-of-Circuit).
the other ends of the test leads to the transistor under
(1) Set the polarity switch to FWD PNP.
test. Be careful to connect the red-coded alligator clip
(2) Connect the cathode of the diode to the red
to the drain lead, the black-coded alligator clip to
lead of the test cable; connect the anode of the diode
the gate lead, and the yellow-coded alligator clip to
to the black lead.
the source lead of the field effect transistor.
(3) Set the function switch to ICO OUT/CKT
(2) Set the polarity switch to FWD PNP when
X1.
testing an N-type transistor, and set it to REV NPN
(4) Read the IR directly in microampere on
when testing a P-type transistor.
the middle (ICO) scale.
(3) Set the function switch to F.E.T. CAL and
(5) If the meter pointer swings off scale, place
the function switch in the ICO OUT/CKT X10
adjust the CAL control for full-scale meter deflection.
range.
(4) Set the function switch to F.E.T. READ,
(6) Multiply the IR reading in microampere by
and read the GM of the transistor under test directly
10 to obtain the true IR reading.
on the meter on the bottom (GM) scale.
h. Diodes, Reverse-to-Forward Ratio (Out-of-
k. Battery Check.
Circuit).
(1) Set the function switch to BAT.
(1) Set the polarity switch to FWD PNP.
(2) The meter pointer should fall in the red
(2) Connect the cathode of the diode to the red
lead of the test cable; connect the anode of the diode
box on the top scale labeled BAT. If the meter pointer
to the yellow lead.
falls outside this box, the batteries should be replaced.
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