Tektronix CURVE-TRACER 576 Instruction Manual page 49

I
I
RB2B1
•""
I
HORIZONTAL
Operating Instructions-Type 576
The interbase resistance can be measured by placing the base 2 lead in the collector
terminal of the test socket and the base 1 lead in the emitter terminal Leave the emitter
lead at the device open and apply voltage across the two bases with the VARIABLE
COLLECTOR SUPPLY control.
SILICON CONTROLLED RECTIFIERS (SCRs)
Required Type 576 Control Settings
Control Required Setting
COLLECTOR
I
PEAK POWER WATTS
Less than maximum power rating of device
POLARITY
I
STEPS
PULSED STEPS
I
Termi na I Selector
I
I
,....,
I
I
I
I
Turn-on
I
Forward Blocking Voltage
I
I
Holding Current
1
\,. "' " ""'
Blockiog Voltoge
l
©
+(NPN)
Pressed when using low gate voltage or
current
Pressed when using high gate voltage or
current
EMITTER GROUNDED BASE TERM STEP
GEN
;·-r-hr-.--r--r-y--r-.--.--r-.
.
:--~H--+--~1--T--~1--+--~ .
:--r-H-~--r-,_-T--r-,_-+--~1
.
~--~H--+--~1--T--~1--+--~
'
'
--·
~--~H--+--r-;--+--r-;--+--~~
.
:--~H--+--~1--T--~1--+--~4
Some Common Measurements
IF vs. V F for different
values of VG
.
. .
v
' •
Tri/•,
,Tv
"'
H
0
R
.
\/
z
'"
"'
s 200
T
'
mv
p
f.
~:
Om
m
"'
"'
The gate voltage or current at which the device turns on can be measured by applying a
specified voltage between the anode and cathode terminals using the VARIABLE COL-
LECTOR SUPPLY control and applying current or voltage steps in small increments to
the gate with the AMPLITUDE switch.
To measure the forward blocking voltage, set the Terminal Selector switch to BASE
TERM OPEN (or SHORT depending on the specification) and turn the VARIABLE
COLLECTOR SUPPLY control clockwise until the device switches to its low impedance
state. The voltage at which switching occurs is the forward blocking voltage.
Holding current is measured in the same manner as forward blocking voltage. Holding
current is the minimum current conducted by the device, while operating in its low
impedance state, without turning off.
The reverse blocking voltage is measured the same way as the forward blocking voltage
except that the POLARITY switch is set to -(PNP).
2-31