b. Operate the FUNCTION switch to the TEST position.
c. Set the PLATE-SCREEN RANGE switch to the position
specified on the tube test data roll chart.
d. Adjust the PLATE fine control until the PLATE meter in-
dicates the exact voltage specified on the tube test data roll chart.
Red calibration marks on the meter scales facilitate this adjust-
ment.
e. Operate the quality SHUNT control to the number specified
on the tube test data roll chart.
f. Operate the GM-SIGNAL RANGE switch to the position
noted on the tube test data roll chart.
g. For the TV2/U, aline the dot on the knob of the GM CEN-
TERING control with the dot on the panel. For the TV-2A/U
and TV-213/U, aline the line marking on the GM CENTERING
knob with the line marking on the panel.
TEST P2 switch. If the tube under test is a multigrid tube, hold
down both the P2 and P3 switches.
i. Read the PERCENT QUALITY meter. If the indication is
below the minimum limit given on the tube test data roll chart,
discard the tube. Tubes that border on the minimum limit may be
usable but should be replaced soon.
Note. W h e n t e s t i n g s o m e d i o d e s , t h e P E R C E N T Q U A L I T Y m e t e r w i l l
deflect off scale. This is a normal condition when the emission of the tube is
far in excess of that required by tube specifications. If the need for balancing
such a diode is present, reduce the setting of the quality SHUNT control until
t h e PERCENT QUALITY meter reads 100. Observe the new shunt setting
and use this setting to compare diodes of the same type.
j. When the 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).
24. Voltage Regulator and Gas Recifier Test
Use the following procedure to test the voltage regulator (VR)
and gas rectifier tubes under minimum and maximum load con-
ditions. The regulating ability of the tube is computed from the
test results. For testing thyratron tubes, refer to paragraph 26.
Set the FILAMENT RANGE and BIAS RANGE switches to the
positions indicated in the tube test data roll chart.
b. Set the PLATE-SCREEN RANGE switch to the position
specified on the tube test data roll chart.
