Fluke 8020A - 2-41. Transistor Tester

2 - 41. Transistor Tester 2 - 43. Transistor type is determined by setting the
switch on the fixture to BETA and observing the
display. If a very low reading (G0.010) is obtained,
NOTE
reverse the test fixture at the input terminals. If the
The transistor tester described in the
collector is now positioned at the COMMON input
following paragraphs provides approximate
terminal, the transistor is a PNP type. An NPN type will
test information. Beta is measured using a
have its collector positioned at the V/kR input
VCE of about 2 Vand an IC of about 200 PA.
terminals. If the transistor is defective the indications
It is very useful for comparative
will be as follows regardless of fixture position:
measurements and matching.
2 - 42.
Select the 2
mS range, plug the fixture shown in
Figure 2
- 7 into the V/KR and COMMON input
terminals, and you have transformed your
8020A into a
transistor tester. Now, plug a transistor into the test
socket and the
8020A will determine the following:
a. Transistor type (NPN or PNP).
b. Collector
- to - emitter leakage (ICES).
c.
Beta from 1 to 1000 without changing range.
a. A shorted transistor will cause an overload
indication.
b. An open transistor will read 0.001 or less.
2
- 44. After the transistor fixture is properly posi -
tioned, set the switch to ICES for the leakage test. The
transistor is turned off in this test (base shorted to
emitter), and should appear as a very low conductance
(high resistance) from collector
- to - emitter. Therefore,
the lower the reading, the lower the leakage. Silicon
transistors that read more than 0.002
(6 PA) should be
considered questionable.
SCHEMATIC TRANSISTOR
UNDER
TEST
TEST
FIXTURE
-
E
cTLypl 1 PLUG INTO
750kn
B
I COMMON AND
A
I V/Kn/nS INPUT
I TERMINALS
ICES I
I *
E >
CONSTRUCTION DETAIL
J1
TRANSISTOR
S1
SOCKET
,- -.
CONNECTOR 0.75 "
WIRE TO
CONTACT OF
TRANSISTOR SOCKET
SPACING GENERAL
ARM
RADIO TYPE 274 MB
Figure 2 - 7. Transistor Beta Test Fixture
2 - 7