Realistic STA-7 - FM RF & IF Alignment

FM RF
&
!F ALIGNMENT
EOUIPMENT
REOUIRED
1. FM
Signal
Generator
.
.
. Output Level: 1 mV
3.
AC Voltmeter
2. Sweep Generator 4.
Oscilloscope
5. D istortion Meter
NOTE:
o
Signal
Generator
output should
be
no
higher
than
necessary
to obtain an output reading.
o
SeTSELECTOR
Switch
to
FM.
.
Maintain
line voltage
at 120 volts.
(UL,
C.S.A.)
(240V
for Australian
models.)
o
Refer
to
P.C.B.
illustrations for
test
points/adjustments.
STEP
GENERATOR
COUPLING
3ENERATOR
FREOUENCY
RADIO DIAL
SETTING
INDICATOR
ADJUSTMENT REMARKS
1
Sweep
Generator
to
"FM
ANT" terminal
on
FM Front
end
board
10.7
MHz
(1400
kHz
Sweep)
Any dial setting
where no noise
or interference
ex ists
Scope
to TP1
at
R144
(MPX
in-
put)
AM/FM/MPX
Board
T101, 102, 103
T104
(Primary)
FM IFT
Adjust
for
maximum
amplitude
and
prop-
er linearity
between
L150 kHz
markers.
Refer
to
Fig.
15.
2
Sweep Generator
to
FM
Antenna
Termi-
nal
thru
FM
Dummy
antenna
(300
ohm)
T101,102
FM IFT
3
Same as above
T104
FM IFT.
(Primary
and
Secondary)
Adjust
for
symmetri-
cal
"S"
curve
as
shown
in
Fig.
'l
5.
4
Signal
Generator
to
FM
Antenna Termi-
nal
thru
FM
Dumml
antenna
(300
ohm)
98 MHz
(4OO
Hz,
10Oo/o
MOD}
Tune for Maxi-
mum reading
on meter.
Distortion Meter
to TAPE
OUT
Jack
T104
FM
Discrim.
(Secondary)
Adjust
for
minimum
distortion.
5
Same as above 86.5 MHz
Tuning
gang
fully
closed
AC Voltmeter
and Scope to
TAPE OUT
Jack
L1
05
(FM
OSC)
Adjust
for
maximum
reading
on meter.
b
Same as above
108.5
MHz
Tuning
gang
fully
opened
TC103
(FM
OSC Trimmer)
7 Repeat
STEPs
(5)
and
(6)
until Tuning Range
Covers exactly from
86.5
MHz
to
,l08.5
MHz.
I
Signal
Generator
to
FM
Dummy
antenna
(300
ohm)
90 MHz
90
MHz
Tune
to
Signal
AC Voltmeter
and Scope
to
TAPE
OUT
Jack
L101
(FM
ANTCoil)
L103(FM RF
Coil; stretch or
squeeze)
Adjust
for
maximum
reading
on AC
Volt-
meter.
I
Same as above
106 MHz
106
MHz
Tune
to Signal
TC101
(FM
ANT Trimmer)
TCl02
(FM
RF
Trimmer)
10 Repeat
STEPs
(8)
and
(9)
until no further
improvement is noticed.
1"1
Same
as
STEP
(8)
ANT. input:
1
mV
98
MHz
98 MHz
Tune to
Signal
T110
Adjust
for
maximum
reading
on the
Receiver's
meter,
12
Same
as STEP
(8)
ANT.
input:
100m\
VR
101 Adjust
so the
Meter
Pointer
on
Receiver
is
90-95% of
full
scale.
-18-