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SECTION
1
OUTLINE
1-1.
CIRCUIT
DESCRIPTION
(See Fig. 1)
Program Sensor
The FM or LW band can be changed automatically
through
the
optical
detection
by
the
following
procedures;
1 Set the FUNCTION
switch (S1) to band selector
position (center position).
2 Then,
Set
the
band
selector
switch
(S3)
to
PROGRAM
SENSOR position.
3 Match
the
dial
pointer
to the
desired
station
marker.
(See Fig. 2)
4 The
FM
or
LW
band
changes
automatically.
1) When
the pointer
matches
only with the FM
station marker:
a) The
light
of
IC301
(Photo
Interrupter)
is
intercepted
by
the
marker,
bias
voltage
is
applied
to the base of Q303
through
R305,
and Q303 is turned on.
b) The
collecter
voltage
of Q303
reduces
and
D203 is turned on.
c) D203 is conducted, B+ voltage through R217 is
decreased.
d) D201
is opened, B+ voltage is not supplied to
the terminal @3) of IC201.
e) FM
circuit
operates
(The
terminal
Q3
of
IC201 serves as a switch).
Note: When B+ voltage is applied to the terminal @3) of
IC201 through R217, R216 and D201, the receiver is
in LW mode.
f) At the same time, PL905 (FM indicator lamp)
lights because of Q304 operating.
2) When
the pointer
matches
only with the LW
station marker:
a) As the light of IC301 is not intercepted, Q303
and D203 are turned off. As a result, B+ voltage
is applied to the terminal Q3) of C201 through
R217
and R216.
On the other hand, the light
STR-414L
of I1C302
is intercepted
by the
LW
station
marker.
b) Q306 and Q305 are turned on.
c) B+ voltage is applied
to L208
(LW oscillator
coil).
d) LW circuit operates. When Q305 is on, PL906
(LW
indicator
lamp)
simultaneously
lights.
3) When
the pointer matches
simultaneously with
both the FM and LW station markers:
a) Q303
and Q304 are turned on by intercepting
the light of IC301. On the other hand, the light
of 1C302 is also intercepted and the bias voltage
is applied to the base of Q306, but because the
collector
voltage
of Q304
is high,
D304
is
turned off. The emitter voltage of Q306
rises
and
B+ voltage is not
applied
to L208
(LW
oscillator coil) and PL906. Consequently, only
the FM station signal is received.
10301
'
FM station
ae
marker
we
The light is
be ae intercepted
<2
by this portion.
LW station
marker
pointer
Q302 and 301
Q302
operates
to improve
the rise time of PL905
(FM indicator lamp) or PL906
(LW indicator lamp)
when tuning the receiver, and at the same time Q302
switches
Q301.
Q301
serves as a high-speed-muting
switch which is turned on or off as soon as the station
signal is tuned or detuned.
1€202
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R304
R305 =
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FM
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Fig. 1
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