Filament Continuity Test

(1) An open circuit or infinite leakage between elements will

p r o d u c e no deflection of the PLATE meter pointer.

( 2 ) A short circuit between two elements will produce a full-

scale deflection of the PLATE meter pointer.

Note. Where the NOTES column indicates a short circuit, full-

scale deflection will appear at those settings.

(3) Read intermediate leakage values on the resistance scale

of the PLATE meter. The amount of leakage is indi-

c a t e d in megohms.

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.

20. Filament Continuity Test

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

b. If the filament continuity test is the only test to be made, set

only the FIL- and the FIL+ SELECTORS switches as indicated

i n the tube test data roll chart. Leave the remaining SELECTORS

s w i t c h e s in their safety positions (par. 15d).

c. Operate the SHORT TEST switch to the V position. For the

T V 2 / U , aline the dot on the PLATE fine control with the dot on

the panel. For the TV2A/U, and TV2B/U, aline the line mark-

i n g on the PLATE fine control with the line marking on the panel.

d. D e p r e s s t h e P R E S S T O T E S T P 1 s w i t c h .

(1) If the FIL. CONT. SHORT lamp glows, the filament is

good.

( 2 ) If the FIL. CONT. SHORT lamp does not glow, the fila-

m e n t is open. Discard the tube.

Note. Occasionally a filament will show continuity when cold,

but will open when it warms up. If this condition is suspected,

set the FILAMENT RANGE switch to the normal voltage for the

tube under test, let the tube warm up for several minutes, and

repeat the test.

21. Transconductance 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 T E S T p o s i t i o n .

c. O p e r a t e 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

specified on the tube test data roll chart.

W a r n i n g : Do not touch the top cap of a tube under test after

plate voltage has been applied.