c. S e t t h e q u a l i t y S H U N T c o n t r o l t o t h e n u m b e r s p e c i f i e d o n
the tube test data roll chart.
d. Set the FUNCTION switch to the VR position.
e. T u r n t h e S I G N A L - V . R . a n d t h e B I A S f i n e c o n t r o l s t o t h e i r
extreme counterclockwise (zero) positions.
f. D e p r e s s a n d h o l d d o w n t h e P R E S S T O T E S T P 5 s w i t c h .
Note the current through the tube as indicated on the PLATE
meter and note the reading of the PERCENT QUALITY meter.
g. W i t h t h e P 5 s w i t c h h e l d i n i t s o p e r a t e d p o s i t i o n , a d j u s t t h e
S I G N A L - V . R., PLATE, and SCREEN fine controls until the VR-
50 MA scale of the PLATE meter indicates the minimum load
current through the tube as specified on the tube test data roll
chart. Note the reading of the PERCENT QUALITY meter.
h. W i t h t h e P R E S S T O T E S T P 5 s w i t c h s t i l l h e l d i n i t s o p e r -
a t e d position, adjust the SIGNAL-V.R. fine control until the VR
50 MA scale of the PLATE meter indicates the maximum load
c u r r e n t specified on the chart. Note the reading of the PERCENT
QUALITY meter.
i. D e t e r m i n e t h e r e g u l a t i n g a b i l i t y o f a t u b e b y t a k i n g t h e
difference between the maximum and minimum load currents
through the tube as read on the PERCENT QUALITY meter.
If the difference between the two readings is greater than the
maximum difference indicated on the tube test data roll chart,
discard the tube.
Note. A quality SHUNT control setting of 50 is specified for many voltage
regulator tubes. When so specified, the reading on the PERCENT QUALITY
meter indicates directly the voltage drop across the tube under test. The
difference between the voltage drop at minimum and maximum load currents
as read on the PERCENT QUALITY meter then is equal to the regulating
ability of the tube in volts.
j. W h e n t h e t e s t i s c o m p l e t e d , s e t t h e O N - O F F p o w e r s w i t c h
to the OFF position, remove the tube under test from the test
socket, and return all switches and controls to their safety posi-
tions (par. 15d).
peres) of Triode Tubes
a. P e r f o r m t h e o p e r a t i o n s i n d i c a t e d i n p a r a g r a p h s 1 5 a n d 1 6 .
b. S e t a l l S E L E C T O R S s w i t c h e s a s i n d i c a t e d o n t h e t u b e t e s t
data roll chart with the exception of the PLATE and SCREEN
SELECTORS switches.
c. Set the PLATE selector switch to the 0 position.
29
