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D.
edjusting the
fnter-Tone
Timing
!{odulate
RF
sigmal generator
sith
Tone A.
Connect
oscilloscope
to
Pin
17
of
IC3O3.
Adjust
R317
for this
period.
One
shot period
-
period
of lst
tone + period delay + period
2nd tone.
l,lodulate
RF
signal with the
t^we-tone sequence.
ttre
message
Light wiJ'l
co'm'on
and
the
squelch
will
open.
E:<ample:
SupSr,ose
the following
frequencies
were
needed:
TONE
A
-
349.0
TO!{E
B
-
389.0
TOiIE
C
-
410.8
Usiog an accurate frequency counter
-
lhe
reading
at
Pin
l of
fC3Ol
urrst be adjusted
to 8x'
349.0
ltz
=
2,792
Hz.
lhe
adjustaent
is
done
rith
R301.
1.
2.
3-
t
ll
I
rl
t
the order
of
the next trrc
Tones
B
and C
is
uningrcrtant.
witlr the
probe
oar
Pin 2
of
IC302 and JO301
pulled up, adjust
R318
for
eight.times
one
of
the otlrer tones
-
say
Tone
C, 8
x
41C.8 Hz
-
3,286.4
Ez.
Norr
gror:nd
the
junper against the
case and
adjust
a32O
for I x
389.0
llz
=
3
,112 IIz.
Norr
adjust the inter-tone
tining
according
to
ycur requi.remeits.
Suppose
tlre
pe=iod
of
the
first
tone
is
.75 sec.
and
the.pe:iod
between tones
is .5
sec
the final
tone
is also
.75 sec,
then
One
shot neriod = period
of lst
tone + period. delay + period
2nd tone
=
.75s
+
.5s
+75s
=
2s
The
adjustment
is
nade
with
R317
and
set with the
scope
probe on
pin
17
of
rc303.
To do
the
sane exanple problem
with
an
oscilloscope i:rstead
of
a
frequency
counter
-
1
t-
=
.=..358x10-6
-oscA
8
x f*
Set
the
scope
for
about
50
x
1O-6s7Div
Then
divide
35E
x rojr
=
7.16
Div - for
one cycle
50
x 10--\
Div
The
other
two tonbs
are set
in
the
sanre
fashion.
0RAWt{
DATE
srzE
A
PART
NUI'8ER
TP14-219
Rev.
.q
AFPROYED
i? .
__7_--T
/
44t:
i f
/.Jt,,1.t2.-
0ATE
u
/,
rJ-*+
DO NOT
SCALE
DWG.
SCALE
t3
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