The 1-megohm resistors required to test the
a. P e r f o r m
the
starting
procedures
(par.
6CD7 and the 6DA5, and the 30-volt battery
17).
required to test the 6360 and the 6524, are
b. Set the controls for the tube under test
not
supplied
with
the
test
set.
The
selectors
as indicated in the test data book, and set the
are set for the tube under test in the normal
POWER switch to ON.
manner.
However, before t h e P O W E R s w i t c h
c. Set
the
FUNCTION
SWITCH
to
is set to the ON position, the resistors or the
SHORTS
1.
battery is connected to the test socket pins as
d. C o n n e c t a t e s t l e a d t o e a c h o f t h e N O I S E
directed in the test data book.
jacks.
C a u t i o n : Disconnect the 30-volt battery be-
e. Connect the test lead from the left-hand
fore resetting any of the selector switches.
NOISE
jack
to
the
chassis
of
the
radio
re-
b.
Voltage
Regulators. When
voltage
regu-
ceiver or the audio amplifier.
lator tubes are tested, sufficient voltage must
f. C o n n e c t
the
test
lead
from
the
right-
be applied to ionize the gas and to cause the
hand NOISE jack to either the antenna of a
voltage
regulator
tube
to
conduct.
Refer
to
radio receiver or to the input of an audio am-
the test data book for the proper use of the
plifier. Turn the radio receiver or the audio
pushbuttons and for control settings.
amplifier power switch to the on position.
c.
Thyratrons. To test thyratrons, set the
g. T a p t h e t u b e u n d e r t e s t w h i l e t h e F U N C -
controls as indicated in the test data book.
TION
SWITCH
is
turned
from
position
1
Press
the
proper
pushbutton
and
adjust
the
through position 5.
BIAS control until the tube strikes; this is in-
h. Intermittent
disturbances
within
the
dicated by a glow between the tube elements
tube
which
are
too
brief
to
register
on
the
and
a
sharp
rise
of
the
meter
pointer.
The
SHORTS lamp will be reproduced as static by
limits
of
the
bias
voltage
between
which
the
the
loudspeaker.
tubes should strike are shown in the test data
i. T u r n o f f t h e t e s t s e t ( p a r . 2 6 ) .
book. After the tube strikes, the condition of
the tube is read on the meter.
Panel Lamp Test
d. Tuning Eye Tubes. Set the controls as
The receptacle in the center of the large,
indicated
in
the
test
data
book.
When
the
7-pin socket (fig. 7) is used to check panel
proper pushbutton is depressed, note the effect
lamps.
on the tuning eye and compare it to the data
a. P e r f o r m
the
procedures
in
paragraph
in the N o t a t i o n s c o l u m n .
When
the
eye
is
17a through d and f .
closed, a thin, bright line is observed; when the
b. S e t
the
FILAMENT
selector
switches
to
eye is open, a wide, dark area is observed.
HR.
25. Testing Subminiature Tubes
c. S e t
the
FILAMENT
VOLTAGE
switch
to the proper voltage for the lamp to be tested.
Subminiature tubes are tested in SUB. MIN.
If
the
exact
voltage
is
not
known,
set
the
sockets X109 and X110 (fig. 9).
FILAMENT
VOLTAGE
switch
to
0.6
volt
a. Subminiature
tubes
of
the
round
type
and increase the voltage as required.
with
short
wire
leads
or
pins
are
tested
in
d. Insert
the
lamp
in
the
receptacle
and
special socket X110. This circular socket has
press
the
center
contact
of
the
lamp
firmly
eight contacts.
against the bottom of the receptacle; then tilt
(1) Several basing arrangements (fig. 10)
the
lamp
until
the
metal
shell
makes
contact
are used for these tubes. The arrows
with
the
rim
of
the
receptacle.
A
defective
near several of the tube bases in fig-
lamp will not light.
ure 10 indicate the location of the dot
on
the
base
of
the
tube.
Check
the
Notations
column
in
the
test
data
24. Testing Special Tube Types
book;
examine
the
tube
and
identify
a.
Special
Testing
Procedures. Certain
the basing. Use adapter E104 (par.
electron tubes, such as the 6CD7, 6DA5, 6360,
16a) when the subminiature tube has
and 6524, require a special testing procedure.
long leads.
