ated for the PLATE SELECTORS switch on the tube test data
roll chart.
e. S e t t h e G M - S I G N A L R A N G E s w i t c h t o t h e F p o s i t i o n .
f. A d j u s t t h e S C R E E N f i n e c o n t r o l u n t i l t h e v o l t a g e s p e c i f i e d
o n the tube test data roll chart for the PLATE meter is indicated
o n the SCREEN VOLTS meter.
Note. It may be necessary to set the PLATE-SCREEN RANGE switch to
a new setting, moving the switch in a counterclockwise direction, so that the
SCREEN VOLTS meter can indicate the voltage specified for the PLATE
meter.
g. Adjust all other fine controls as required on the tube test
data roll chart for the tube under test.
h. Turn the SIGNAL-V.R. fine control to its maximum counter-
c l o c k w i s e position.
i. S e t t h e F U N C T I O N s w i t c h t o t h e V R p o s i t i o n .
j. 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 0 .
k. Depress the PRESS TO TEST P5 switch. Be sure the proper
voltages for the tube being tested appear on all other meters.
Note the reading on the 0- to 50-milliampere (ma) scale on the
PLATE meter.
l. R e l e a s e t h e P R E S S T O T E S T P 5 s w i t c h .
m. When the test is completed, set the ON-OFF power switch
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).
Use the following procedure to determine the firing potential
of thyratron (TH) tubes. Thyratrons are also called gas triodes
o r grid glow tubes. The firing potential may be defined as the grid
v o l t a g e at which the tube begins to conduct.
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 8 .
b. Set the FUNCTION switch to the VR position.
c. S e t t h e P L A T E - S C R E E N R A N G E s w i t c h t o t h e p o s i t i o n
s p e c i f i e d on the tube test data roll chart.
d. 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.
e. S e t t h e S I G N A L - V . R . f i n e c o n t r o l t o i t s e x t r e m e c l o c k w i s e
(maximum) position.
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.
