4-21
BETA MEASUREMENTS
If the transistor is to be tested out of the circuit, plug it into the test jack located on the right-hand
side below the meter. If the transistor is to be tested in the circuit, at least 300 ohms must exist between E-
B (emitter to base), C-B (collector to base), and C-E (collector to emitter) for accurate measurement.
Initial setting of the test set controls is performed as follows:
1. Set the function switch to BETA.
2. Set the POLARITY switch to PNP or NPN (depending on the type of transistor under test).
3. Set the RANGE switch to X10.
4. Adjust METER ZERO for zero meter indication (transistor disconnected).
5. The POLARITY switch should remain OFF while the transistor is connected to or disconnected
from the test set; it should then be set to PNP or NPN, as in step 2 above.
If the beta reading is less than 10, perform the following steps:
1. Reset the RANGE switch to X1 and reset the meter to zero.
2. After connecting the yellow test lead to the emitter, the green test lead to the base, and the blue
test lead to the collector, plug the test probe (not shown) into the jack located at the lower right-
hand corner of the test set.
3. When testing grounded equipment, unplug the 115-volt line cord and use battery operation. A
beta reading is attained by multiplying the meter reading times the RANGE switch setting. Refer
to the transistor characteristics book provided with the tester to determine if the reading is
normal for the type of transistor under test.
ICO MEASUREMENTS
Adjust the METER ZERO control for a zero meter indication. Plug the transistor to be tested into the
jack, or connect the test leads to the device. Set the PNP/NPN switch to correspond with the type of
transistor under test. Set the function switch to ICO and the RANGE switch to X0.1, X1.0, or X10, as
specified by the transistor data book for allowable leakage. Read leakage on the bottom scale and
multiply by the range setting figure as required.
ELECTRODE RESISTANCE MEASUREMENTS
Connect the in-circuit probe test leads to the transistor with the yellow lead to the emitter, the green
lead to the base, and the blue lead to the collector. Set the function switch to the OHMS E-B position and
read the resistance between the emitter and base electrode on the center scale of the meter marked OHMS.
To read the resistance between the collector and base and the collector and emitter, set the function
switch to OHMS C-B and OHMS C-E, respectively. These in-circuit electrode resistance measurements
are used to correctly interpret the in-circuit beta measurements. The accuracy of beta times 1 and 10 range
is 15 percent only when the emitter-to-base load is equal to or greater than 300 ohms.
DIODE MEASUREMENTS
Diode in-circuit quality measurements are made by connecting the green test lead to the cathode and
the yellow test lead to the anode. Set the function switch to DIODE IN/CKT and the RANGE switch to
