Realistic STA-7 - FM Stereo Alignment

FM
ALIGNMENT
SET-UP
3OOO DUMMY
FM ANT
Sweep
Gen.
Figure 15
FM
STEREO ALIGNMENT
Equipment
Required
1. Stereo
Modulator
2.
FM
Signal Generator
. .
3.
AC Voltmeter
4.
Oscilloscope
5. D
istortion Meter
6.
Frequency
Counter
Note:
See
P.C.B.
illustration
for
alignment/test
points.
Preliminaries
Set SELECTOR
switch
to
FM
STEREO.
TAPE
OUT
{L or R)
AC V.T.V.M.
DISTORTION
METER
generator.
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Figure
16
Connect Stereo Modulator
to
EXT.
Mod.
terminal
on
FM
signal
Modulation
Level
of 19
kHz Pilot
Signal
.....8-10%
Output Level
..... 1 mV
Frequency
.........
Approximately
98
MHz
Deviation
75
kHz
1OO7o
modulation
of composite
signal
FM
SIGNAL
GENEBATOR
SCOPE PATTERN
MULTIPLEX
& SEPARATION
ALIGNMENT
STEP
SIGNAL GENERATOR
COUPLING
STEREO
MODULATION
IND ICATOR
ADJUSTMENT
REMARKS
1
Connect
to
FM
Antenna
terminal
thru
FMdummy
antenna
(300
O).
Mono.
1
kHz
(1000
Hz, No
Mod)
lnput
1
mV
Counter connected
toTP2
at
Pin
12 o{
IC
VR
103 Adjust for
19
kHz
.t50 Hz
on Counter.
Refer
to
Fig.
17.
2
Same as above
Composite MPX
Signal
1
kHz
on Left channel
ONLY
AC
Voltmeter
con-
nected
for
TAPE
OUT
jack
of
R
ight
channel
VR 102
(Separation
)
Adjust
for
minimum
read ing.
Refer
to
Fig.
18.
3
Same as above
Composite
MPX
Signal
1 kHz
on
Right
channel
ONLY
AC Voltmeter con-
nected 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
-30
dB re
same channel
out
(i.e.
30 dB
separation
).
5
Same as step
1 Composite
Signal
1
kHz
AC
Voltmeter
con-
nected
to
TAPE
OUT
jack
Select
value
of
R167.
With
10
pV
antenna
input
signal, stereo
indicator lamp
should come on.
r
-
19-