Sony ICF-111B - Page 3

ICF-111B
foresee cero
1-2.
INTERNAL
VIEW
<_<
171-502-267
speaker
1-4017-305-22
coil, ferrite bar
antenna
3-830-339
drum, volume indicate
3-837-619 ©
drum, dial
1-151-196
capacitor,
tuning
1-507-332
jack ass’y, 3-unit
-837-
'
3-825-643
conteet
platé
@,
battery
~
contact
plate,
negative
‘
battery
positive
Fig. 1-2.
1-3. BLOCK DIAGRAM
t TEL ANT
DO5, 06
FM DET
Q09.
FM IF AMP
Q70
POWER AMP
sw Re
ANT COIL a
SP
MW
ie
Ew
ae
ANT COIL {||
POWER AMP }
!
Lo
ro
our
|
°
|
ohorowe
Fig. 1-3.
ae
RESONANCES
INDICATING
CIRCUIT
Idling
collector
current
flows
at
no
input
sig-
nal,
but
the
transistor
has
a
high
sensitivity
to
an
input
signal.
When
an
i-f
signal
(of
455
kHz
or
10.7
MHz)
is
added
to
the
base,
collector
current
flows
in
proportion
to
the
signal
strength.
Thus,
the
LED
(D202)
is
illuminated
by
the
collector
current.
The
model
ICF-111B
resonance
indicating
circuit
uses
an
LED
(Light
Emitting
Diode).
i-f
section
(¥) D202 (LED)
IC
Q207
|IC
—
VB
curve
iluminating
current
B201
|
=.
Output
signal
Fig.
1-4.
The
circuit
is
shown
in
Fig.
1-4.
Resistors
_.at
no
input
signal
R203,
R204,.R205,
and
diode
D201
keepaconstant
=
$$[Loooo——=
Ve
bias
voltage
(VB)
on
the
base
of
Q201.
The
bias
js
set
at
the
cut-off
point
of
Q201.
Here,
D201
a
stabilizes
the
bias
against
a
variation
in
source
volt-
base
|
bias
Fig.
1-5.
age or temperature.