Fm Mpx Section - Pioneer QX-949A Series Service Manual

8.3
FM MPX
SECTION
1. Set FM signal generator at external modulation.
Connect
to
unit's FM
antenna terminals
via
300-ohm balanced dummy antenna. Set FM
SG
output to 60d8.
2.
Adjust MPX
signal generator
to
obtain
main
signal modulation
of
lkHz,
67.5kHz frequency
deviation. Connect
to
FM
SG's external modu-
lator
terminals.
3. Connect the
oscilloscope horizontal inputs to
MPX sG's
PILor
our
terminals and vertical
inputs
to No.
18 terminal of tuner
assembly.
4. Tune
unit
and
FM
SG
to
g8MHz.
5. Produce a Lissajous pattern on oscilloscope
and
adjust
VRl
to
make the pattern still.
6.
Then set
signal generator
for
modulation
of
L
(later
R)
and
pilot.
Adjust
vR2 to
obtain
muimum
channel separation.
Tuner
assembly
o
Er
4
"@
o
Oscilloscope
FM
o
-o
o
L
c,
MPX
signal generator
signal
generator
t-,l
^
l-7-l /' \
/\
(o)
\:_,,
O
oo
30