Realistic STA-78 - AM RF and IF Alignment

AM RF
&
IF ALIGNMENT
EOUIPMENT REOUIRED
1.
AM Signal Generator
2.
AC
Voltmeter
3.
Oscilloscope
4. Distortion
Meter
Figure 7
Note:
*Signal
generator
output should be
no higher than necessary
to obtain an output reading.
*Maintain
line voltage
at 12O
volts,
60
Hz
AC
(UL
&
CSA)
(240
volts,
50
Hz
AC
for
Australian
models).
"Set
SELECTOR Switch to
AM.
*See
P.C.B.
illustrations
for
alignment
points/adjustments
and Figure 7.
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AC
VOLTMETER
METER
TAPE OUT
(LorR)
Figure
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STEP
SIGNAL
GENERATOR
COUPLING
SIGNAL GENERATOR
FREOUENCY
DIAL
SETTlNG
INDICATOR
ADJUSTMENT
REMARKS
1
Connect
standard
loop
ANTENNA
to Signal
Generator
and
radiate
signal
into the AM
Fer-
rite Antenna.
See
Figure
8.
455
kHz
(400
H2,30% mod.)
Point
of
non-inter-
ference
(near
600
kHz)
Scope and,
AC
Volt-
meter to
TAPE OUT
Jack.
r202
T203
(AM
IFT)
Adjust
for
maxi-
mum reading
on
meter.
2
Same as STEP 1. 510 kHz
(400
H2,30%
mod.)
Tuning
Gang
fully
closed.
Same
as
STEP 1.
L2O3
(AM
OSC
Coil)
Adjust for maxi-
mum reading
on
meter. Refer
to
Figures
7 and
8.
3
Same as STEP 1 1650 kHz
l4OO
H2,30% mod.)
Tuning
Gang
fully
opened.
Same as
STEP
1.
TC105
(AM
OSC Trimmer)
Adjust for maxi-
mum
reading on
meter. Refer
to
Figures
7
and 8.
4
Same as STEP 1 600 kHz
(400
H2,30% mod.)
600 kHz
Same
as
STEP 1.
L8O2
(AM
ANT.
Coil)
Adjust for maxi-
mum reading
on
meter.
Refer
to
Figures
7 and
8.
5
Same
as
STEP
1
1400 kHz
(400
Hz,
30%
mod.)
14OO
kH,z
Same as
STEP 1.
TC104
(AM
ANT. Trimmer)
Adjust
for
maxi-
mum reading
on
meter. Refer
to
Figures
7 and
8.
6
Repeat
STEPs
4
and
5 until no further change is noticed.
7
Same
as
STEP
1 1000 kHz
(400
kHz,30% mod.)
Output level
to
100
mV/m
1000 kHz
AM
Signal
Meter on
Set.
VR201
Adjust
so the
Meter
Pointer
on
Receiver is
at about
85%
of full scale.
2
-__.4
AM BAR ANTENNA
(6ocm)
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