Simpson 1000 - Page 44

SPECIAL APPLICATIONS
control grid is connected to pin #4, and the push button
for the #4 circuit is D. Press the D button and read the
OHMS scale of the meter again. If the 100K reading appears
again in this test, the leakage resistance is between the
cathode and the control grid. If the reading shows in the
black markings on this test, the leakage is between the
filament and the cathode.
Use this system to help identify which elements are in-
volved in an inter-element leakage when the information
will aid you to evaluate a tube for a special application.
You will know the internal condition of the tube and can
judge the circuit results and establish the necessary
precautions intelligently.
SELECTING TUBES FOR APPLICATION
IN MATCHED CIRCUITS
The dynamic Plate Conductance tests which you make with
your Simpson Tube Tester Model 1000 will furnish indica-
tions which you may use to match the characteristics of
several tubes of the same type for circuit applications
which require balanced action. The same tests can be used
to match two sections within one dual-type tube. Examples
could be push-pull amplifier circuits in the amplifiers of
an oscilloscope, and two sections of an electronic bridge
network.
Test each tube or section in the normal manner, and record
the interelement leakage resistances and percent of Plate
Conductance for each one. Match these results in order to
select tubes which have similar characteristics.
42
————— a