User's Manual

c. Set the quality SHUNT control to the number specified on

the tube test data roll chart.

d. Set the FUNCTION switch to the VR position.

e. Turn the SIGNAL-V.R. and the BIAS fine controls to their

extreme counterclockwise (zero) positions.

f. Depress and hold down the PRESS TO TEST P5 switch.

Note the current through the tube as indicated on the PLATE

meter and note the reading of the PERCENT QUALITY meter.

g. With the P5 switch held in its operated position, adjust the

SIGNAL-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. With the PRESS TO TEST P5 switch still held in its oper-

ated position, adjust the SIGNAL-V.R. fine control until the VR–

50 MA scale of the PLATE meter indicates the maximum load

current specified on the chart. Note the reading of the PERCENT

QUALITY meter.

i. Determine the regulating ability of a tube by taking the

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. 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).

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

peres) of Triode Tubes

a. Perform the operations indicated in paragraphs 15 and 16.

b. Set all SELECTORS switches as indicated on the tube test

data roll chart with the exception of the PLATE and SCREEN

SELECTORS switches.

c. Set the PLATE selector switch to the 0 position.

d. Set the SCREEN SELECTORS switch to the position desig-