d. A d j u s t t h e P L A T E a n d S C R E E N f i n e c o n t r o l s u n t i l t h e
PLATE and SCREEN VOLTS meters indicate the exact voltages
specified on the tube test data roll chart. Red calibration marks
on both meters facilitate this adjustment.
e. S e t t h e B I A S R A N G E s w i t c h t o t h e v o l t a g e o r p o s i t i o n
s p e c i f i e d on the tube test data roll chart.
f. A d j u s t t h e B I A S f i n e c o n t r o l u n t i l t h e G R I D B I A S V O L T S
m e t e r indicates the exact grid-bias voltage specified on the chart.
g. If the bias voltage indication is over 80 percent of full scale
at a low plate voltage setting, it may be difficult to obtain the
required bias voltage. In such a case, use the next higher setting
of the BIAS RANGE switch.
h. O p e r a t e 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 g i v e n o n
the tube test data roll chart.
i. A d j u s t t h e P E R C E N T Q U A L I T Y m e t e r t o z e r o ( p a r . 1 7 ) .
j. O p e r a t e 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 p o s i t i o n
specified for the quality test.
k. Adjust the SIGNAL-V.R. fine control until the pointer of the
SIGNAL meter is on the red line.
l. Depress the PRESS TO TEST P4 switch to its locking posi-
tion.
m. Read the percent quality for the tube under test on the
PERCENT QUALITY meter.
(1) If the reading is below the minimum limit indicated on
the tube test data roll chart, discard the tube.
(2) If the reading borders on the minimum limit, the tube
may be usable but should be replaced soon.
(3) If the PERCENT QUALITY meter indication is beyond
full scale, the tube may be gassy. Perform the gas test
n. Release the P4 switch.
Note. A multisection tube may be listed several times on the tube test data
roll chart. If this is the case, reset the SELECTORS switches for each
listing in the tube test data roll chart. Repeat the short test and the trans-
conductance test for each new setting.
o. When a test is completed, set the ON-OFF switch to the OFF
position, remove the tube under test from the test socket, and
return all switches and controls to their safety positions (par.
15d) .
U s e the following procedures to determine whether an amplifier
