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r
1.
.001
R2l1
10
kc
2.
.01
ri220
1kc
3.
4.
5.
.1
11229
100
\
1.
R238
10
\
10.
;7247
1
'\,
Sect.
Mage
3
shorl the shaft to
ground)
to the center oI the range
th.it
produces a
stable indication. Watch
tie
panel
neo[ indicator to make certain the instrument is
oPe
rating Properly.
d.
Decrease
the input voltage amplitude
to .6 volt
rms
and
rotate Rl22 (counterclockwise) until
the instrument just produces a stable ifldication.
Watch the neon indi.cator
to
make
certain the in-
strument is opet'ating
ProPerIY.
e,
Repeat
step
c.
with the reduced input voltage
and
then repeat step
d.
starting with
.1122
max-
imum
ctrockwise and
rotating
it
counterclockwise
until
the instrument just produces
a
stable indication.
4.8
ADJUSTING THE
DECADE COUNTER INPUT
The
rmplitucle ol thc driving putses for tire
decade
counter units
is
adjusted l)y means of R184. This
control
is
located
under the
chassis, iust
below the
PHOTOTUBE
VOLTAGE connector
on
the back of
the
instrument. This control sets the bias
on
thc
gate
tube
(V101A) when
the gate
is
open
(ne'u indicator
on).
Set
the
controls
as
follows;
FI'NCTION
SELECTOR
tO
CHECK
FREQUENCY
UNIT switch
to
any
GATE
T[\4E
MANUAL GATE switch
to
OPEN
CunnecI
r
vtvm to pin
2
of
V101.
Adjust
R184
to
get -16 to -18 volts
o{
bias on pin 2 of V101 with
MANUAL GATE switch
open.
U
the bias
is
set
correctly,
the instrument should
indicate exactly
100
kc when on SELF CIIECK
over
Iine voltage
range
at
103
-
127
volts.
Ii
the indi-
cation
is ofl by t
1
count,
it
is
due
to
a phase
dif-
ference
between
the
gate
control pulses
and
the coun-
ter
input
waveform,
an
error
that
is
aLways
present
in this type oI
counter.
This
phase
dilierence
may
be
corrected
by
adjusting the bias
on
V101
slighU.y.
II this
does
not compensate,
trouble may exist
in
the
Signa] Gate
or
Gate
Control
Circuits. Ii
the
+
1
count
error
can not be
corrected by increasing the
Gate
tube
bias
there
wiII
be no
adverse
efiect
on
the
accu-
racy oI the
instrument.
(Refer to Section
2-3).
The
important item
is to
insure
adequate
driving-pulse
amplitude
for
the decade counter
units.
STD.CATE
Adjust
TIME
SEC.
Desired
Count
00100.
(kc)
0100.0
(kc)
100.
00
(kc)
00000
(cps)
0000.
0
(cps)
In step
5 above
tie
desired count
is ofl register
alrd
it
is
necessary to watch the leJt
hand
counter
and
count
the number
of complete counting cycles
(0 to
I
and
back
to 0)
it
goes
through.
When
the
1^/
phan-
tastron is properly adjusted, the IeIt
hand
counter
will
go
t}lrough
10
complete counting
cycles
and
stop
at
zero. In
step
4
the
desired
count
is
also
olf
reg-
ister
but incorrect adjustment
will
be indicated
as
a
number
otller
tlran
zero
on
the left
hand
counter.
4.7
ADJUSIING
THE
AMPLITUDE
DISCRIMINAIOR
NOTE
Adj
ustment of
Amplitude Discriminator
Unit
2 should be made
belore
proceeding
with Unit
3.
Set
the
controls
as
follows:
FUNCTION SELECTOR
tO
TIME iNTERVAL
Start
and
Stop TRIGGER
LEVEL cqntrols to
zero
DISPLAY
TIME control to minimum
SEP.
-COM.
switch
to
COM.
TIME UNIT to MILLISECOND
TRICCETt SLOPE
switches
to opposite polarities
(one
to +
and
the
other to -)
MANUAL GATE switch closed.
a.
Set
R122
(SENS
UNm
3)
to its
maximum
clock-
wise position.
b.
Corulect
a
100
-cyc
le
voltage having an
amplitude
of 3 volts rms to eithel, the START or
STOP
input terminaL
c.
Adjust
R2 tocated on
top
oI Amplit'rdc
Dis(rjmi-
nator 3
(usj.ng
a
small screwdriver that
wiIl
not
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