Interelement Leakage Test

3A6GT

3Q4

3B7

3Q5QT

3D6

3S4

3LF4

3V4

d. I f t h e l a m p b u r n s c o n t i n u o u s l y o r g l o w s d u r i n g t a p p i n g i n

a n y one of the five positions of the SHORT TEST switch, the tube

contains short-circuited electrodes. Discard the tube unless an

e x c e p t i o n is noted on the tube test data roll chart.

e. D i s r e g a r d a m o m e n t a r y f l a s h o f t h e F I L . C O N T . S H O R T

indicator lamp while the SHORT TEST switch is being moved

f r o m one position to the next. This flashing usually is caused by

t h e charging of a capacitor in the test circuit.

Note. Some tubes normally test as shorted when the SHORT TEST switch

is in certain positions. Before discarding a tube that shows a short, check

the tube test data roll chart NOTES column for information on normal short

indications.

f. 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 s w i t c h t o t h e

O F F position, remove the tube under test from the test socket, and

return all switches and controls to their safety positions (par.

19. Interelement Leakage Test

Follow the test procedure in a t h r o u g h e below to determine the

interelement leakage (LK) in megohms between electrodes of the

tube under test.

a. P e r f o r m t h e o p e r a t i o n s d e s c r i b e d i n p a r a g r a p h s 1 5 a n d 1 6 .

b. O p e r a t e t h e F U N C T I O N s w i t c h t o t h e L E A K p o s i t i o n . T h i s

p o s i t i o n connects the PLATE meter into the circuit to serve as an

ohmmeter for this test only.

c. S e t t h e o h m m e t e r ( P L A T E m e t e r ) t o z e r o a s f o l l o w s :

( 1 ) Operate the SHORT TEST switch to the V position.

(2) Turn the PLATE fine control to its maximum counter-

c l o c k w i s e position.

( 3 ) Depress the PRESS TO TEST P1 switch.

( 4 ) With the P1 switch held in its depressed position, adjust

t h e PLATE fine control until the pointer of the PLATE

meter indicates zero (250 on center scale) on the ohm-

meter (top) scale.

(5) Release the P1 switch.

d. O p e r a t e t h e S H O R T T E S T s w i t c h s l o w l y f r o m t h e O P E R .

p o s i t i o n to positions V, W, X, Y, and Z; at the same time, watch

for a deflection of the PLATE meter pointer.