Heathkit TT-1 - Page 10

Grid Cap Grid clip should be con-
nected to the tube cap.
Thyra Thyratron.
X1, X2, X3, (In the REMARKS column)
etc. Indicates the factor used to
multiply the Gm scale read-
ing to obtain the actual Gm
value,
Additional abbreviations that appear in the SIG
ales ™n
VLuLuills are:
R
D
VR
oo
- Tube is to be tested as a rec
- Tube is to be tested as a diode.
- Voltage Regulator tube.
- Test procedure for eye tubes is to be
used.
plug the line cord into a
olt, 60 cycie source. or <
With the LINE TEST switch pulled down,
adjust the meter pointer to the LINE CHECK
arrow at midscale by rotating the SET LINE
control, then release LINE TEST switch.
Refer to the roll ch
avon. te = +. a Ne
to be tested.
t for data on the tube
Adjust PLATE, BIAS, FIL, METER, SIG and
anT Moma
Big bow 1 ORS to corr respond to a roll chart
information. The K, PandG ae pea
always be in Position 1
stated.
-
E
E
i
Set
LEAKAGE
switch
to
Position
1
and
insert
the
tube
in
the
proper
socket.
Allow sufficient warmup time and then reset
the SET LINE control, if meter pointer is
not on the LINE CHECK arrow with LINE
TEST switch pulled down.
-_ i=)
be rejected. In certain critical applicat
such as audio preamplifiers or certain TV
circuits, performance may be impaired if
the heater-cathode and/or interelement
leakages are less than 2 megohms.
NOTE: A leakage indication may be normal
if listed in the REMARKS column. A meter
indication on position 1 indicates heater-
cathode leakages. Readings on Positions 2,
Buus 20 Aa So atilige Vil SU ibis
3, 4 and 5 indicate suppressor grid, plate,
.
enrrnaan arid and
wV EUV Brau CALAMA
respectively.
A
control grid leakages,
With LEAKAGE switch in the TUBE TEST
position, depress Gm TEST switch for Gm
reading. If the meter indication is less than
the value given in the R.P. column, the tube
should be rejected.
NOTE: The reject point listed on the roll
chart is given in terms of the basic 0-3000
micromhos scale. If the meter reads below
the reject value, the tube should be con-
it is possible, in
PyeSssvil,
sidered faulty.
WAMU] UUW acrusry
certain special applications, that a tube
must be replaced even though its Gm is
still above the given reject point. Converse-
ly, other tubes may function satisfactorily
in certain equipment, even though their Gm
has dropped to as low as 50% of their nomi-
nal or "bogie values. In accordance with
EIA
(RETMA)
standards,
65%
of
the
nominal
Gm
value
has
been
established
as
the
re-
jection
point
(R.P.).
The
multiplying
factor
in the REMARKS column is used only to
obtain
the
actual
Gm,
which
is
derived
by
multiplying the reading on the 0-3000 micro-
hte! odeN Aetrel tiie Peatiilis Wee
mhos
scale
by
the
multiplying
factor.
Again,
this factor is NOT used with ‘respect to the
reject point.
Turn the GRID CURRENT switch to the TEST
position and hold it there for at least 5 sec-
onds. If no increase in meter reading is
the tube is not drawing grid current
SUVS 2 440 VM AWilig Banat LULL
and may be considered "good."' Any meter
deflection during this test indicates the tube
is
drawing
grid
current
and
should
be
re-
jected. There is no scale on the meter to
indicate the magnitude of grid current flow
since any amount may be considered as
However,
owever