Realistic STA-115 - Page 32

FM Stereo
(Multiplex
Equipment Required
1.
Stereo
modulator
Modulation level of
19
kHz
Pilotsignal
. . . . . 8
-
10%
2.
FM
signal
generator
Output
level
-
1mV
Frequency
-
Approximately 98
MHz
Deviation
-
75
kHz, 100% deviation
3.
Audio
generator
of composite
signal
4.
AC
voltmeter
5.
Oscilloscope
6. Distortion
meter
7.
Frequency counter
Set-Up
au 0ro
G ENERATOR
& Separation)
Alignment
Notes:
o
Signal
Generator output
should
be no higher
than necessary to obtain an
output reading.
.
Maintain voltage
at 120
volts
AC, 60
Hz
(U.S.A.,
Canada)
(240
volt
AC, 50
Hz for
Australian
models.)
i----
I
.
S.. SELECTOR switch
to
FM.
I
I
e
Set
MONO
switch to
OFF
(stereo)
position.
I
L___
--]
FM STEREO FM STANOARO
s. G. s.6.
a
a
Figure
33
Figure
32
Connect stereo
modulator
to EXT.
Mod. terminal
of
FM
signal
generator.
Connect
to FM
Antenna
terminal through
FM dummy
antenna
(300S}).
(See
Figure
28
Dummy
Ant.)
Connect oscilloscope,
AC
voltmeter, distortion
meter, and Low Pass filter
(10
Hz
-15
kHz
t0.5
dB,
19 kHz
-
over 45 dB, 38 kHz
-
over 50
dB) to TAPE OUT
jack.
Connect
counter to TP5
(near
lC2O2)
and
GROUND,
and
terminate a22OK
resistor to counter
input in
parallel
(Figure
32).
Adjustment
Check
TAPE OUT
JACK
FX
EXT. A(TEiliA
TERHINAL(3OON)
"f,.*'-,-',-,-
lO
.
tr0oOoDOtrtrOO
O
I C202 LA3390
Step
Stereo
Modulation
lndicator Adjustment
Remarks
1
Mono 1 kHz
(1000
Hz, No Mod.)
lnput 1mV
a
Counter
VR2O3
(19
kHz
Adj.)
Adjust
for 19 kHz
t50
Hz
on
Counter
2
Composite MPX
signal
1
kHz
on left channel
ONLY
.
AC voltmeter
(TAPE
OUT
jack
o{
right channel)
VR2O4
(Separation
)
Adjust for
minimum
reading
on meter.
3
Composite
MPX
signal
1
kHz
on right channel
ONLY
.
AC voltmeter
(TAPE
OUT
jack
of
left
channel)
V R2O4
(Separation
)
Adjust for
mlnimum
reading
on
meter.
4
Repeat
steps 2
and
3
until
AC
voltmeter
reading
is at least
-33
dB.
(i.e.
33 dB separation)
Nominal: 45 dB
5
Composite MPX signal
1 kHz
.
AC
voltmeter
With
5
-
15ptV antenna
input
signal, Stereo
indicator
LED
(D807)
should
come on.
6
Composite MPX
slgnal
1
kHz
a
Distortion meter
With
1mV
antenna
input
signal, Stereo
distortion should
be less than
1.5%.
32-