Realistic STA-21 - Page 10

FM
SIGNAL
GENERATOR
FM ALIGNMENT SET-UP
3OOO DUMMY FM ANT
Sweep
Gen-
FM STEREO ALIGNMENT
Equipment
Required
1.
Stereo
Modulator
. . .. .
2.
FM
Signal Generator
. .
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.
MULTIPLEX
&
SEPARATION
ALIGNMENT
TAPE
OUT
(L
or
B)
AC V.T.V-M-
DISTOBTION
METER
tLrpTatRlsl(470)
Figure 7
Connect Stereo
Modulator
to EXT.
Mod. terminal FM signal
generator.
Modulation
Level
of
19 kt{z
Pilot
Signal
....8
-
10 %
Output
Level ... 1
mV
Frequency
....... Approximately 98
MHz
Deviation
........75 kHz 100
%
modulation
of
composite signal
STEP
SIGNAL GENERATOR
COUPLING
STEREO
MODULATION
INDICATOR ADJUSTMENT
REMARKS
1
Connect
to FM
Antenna
terminal thru FM
dummy antenna(30O
0
)
Mono.
1 kHz
{1000
Hz, No
Mod)
lnput
1 mV
Counter
connected
to
TP 14 at
Pin No
12
of lC
VR 103
Adjust
for 19 kHz
+50
Hz on Counter.
Refer
to Fig. 8.
2
Same as above Composite
MPX
Signal 1
kHz
on
Left
channel
ONLY
AC Voltmeter
connected
for
TAPE OUT
jack
of
Right
channel
VR 102
(Separation)
Adjust
for mini-
mum reading.
Refer to
Fig.
9.
3
Same as above
Composite
MPX
Signal
1 kHz on
Right channel ONLY
AC Voltmeter
connected
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
-33
dB re same
channel
output
(i.e.
33
dB separation).
5
Same
as step 1
Composite
Signal
1 kHz
AC
Voltmeter
connected to
TAPE
OUT
jack
With 10
pV
antenna
input signal,
stereo indicator
lamp should come on.
-
10-