Realistic STA-78 - FM Stereo Alignment

FM
STEREO
ALIGNMENT
EOUIPMENT REOUIRED
1. Stereo
Modulation
Connect Stereo
Modulator
to
EXT.
Mod.
terminal
of
FM
SignalGenerator.
Modulation Level
of
19 kHz
Pilot
Signal
. . .8-1Oo/o.
2.
FM
Signal
Generator
. . Output
Level
-
1 mV
Frequency
-
Approximately
98
MHz
Deviation 75 kHz, 100% modulation
of composite signal
3.
Audio
Generator
4. AC
Voltmeter
5. Oscilloscope
6.
Distortion
Meter
7.
Frequency
Counter
Note:
See
P.C.B.
illustration
for
alignment/test
points.
Preliminaries
Set SELECTOR
Switch
to
FM
STEREO and
MUTE
Switch to
"OFF"
position.
MULTIPLEX
& SEPARATION
ALIGNMENT
STEP
SIGNAL GENERATOR
COUPLING
STEREO
MODULATION
INDICATOR
ADJUSTMENT REMARKS
1
Connect
to
FM
Antenna
terminal
thru
FM
dummy
antenna
(300
ohm).
Mono.
l kHz
(1000
Hz, No
Mod.)
lnput:
1
mV
Counter connected
to
TP
at
Pin
No.
12
of
lC2O2.
VR2O5
Adjust
for
19
kHz
1 50
Hz
on Counter.
Refer
to
Figure
12.
2
Same as above.
Composite MPX
Signal 1 kHz
on
Left channel
ONLY.
AC Voltmeter con-
nector for
TAPE
OUT
Jack
of
Right
Channel.
vR204
(Separation
)
Adjust for minimum
reading
on
meter.
Refer
to
Figure
13.
3
Same as above.
Composite
MPX
Signal
1 kHz
on
Right
channel
ONLY.
AC Voltmeter con-
nector for TAPE
OUT Jack
of Left
Channel.
Same as above. Same
as above.
4
Repeat
STEPs 2 and 3 until AC Voltmeter
reading
is
at
least
-40
dB same channel
output.
(ie.
40
dB
separation).
5
Same as STEP 1
Composite MPX
Signal
1 kHz.
AC Voltmeter
con-
nected
to
TAPE
OUT
Jack.
With
5.5
pV
antenna in-
put
signal, Stereo
indi-
cator lamp
should come
on.
FM
STEREO ALIGNMENT SET.UP
ANTENNA
L(30On)
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Figure
12
-
12-
Figure
13