Procedure for Reading Plate Current (Less Than 50 Milliam-peres) of Triode Tubes

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).

25. Procedure for Reading Plate Current (Less Than 50 Milliam-

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.