accuracy
is
better
than
±l.5%.
For
convenience in setting
the
IF
circuit frequencies, tuning scales are marked
at
455kHz
and 10
.7MHz.
The
RF
output
is
controlled with
the
fine adjuster
and
LOW-HIGH switch.
For
amplitude modulation,
the
audio signal
is
sup-
plied
by
the
modulator,
IC101.
The
modulating
is
done
by
varying
the
supply voltage
at
the
audio rate.
B.
AF
Oscillator/Amplifier and Crystal Oscillator.
An
IC,
IC101
is
used for three functions, depending
on
the
positions
of
the
mode switch.
At
EXT
MOD position,
it
serves as an audio amplifier
for
the
external modulation input. The signal from INPUT
is
applied
to
the
IC101
and
on
to
the
modulator.
The
1kHz signal is generated with use
of
the phase-
shift oscillator.
The
output
is
fed
to
the modulator and
OUTPUT (when used externally).
At
XTAL position,
IC101
acts
as
an oscillator when
a crystal,
1-l5MHz,
is
inserted in the XTAL socket.
The
output
is connected
to
the
LOW
terminal
of
LOW-
HIGH
output
switch. The signal
is
available
at
the
OUT-
PUT
connector
at
the
LOW
position.
It
is
possible
to
super-
impose the
RF
oscillator signal on
the
crystal oscillator
output
at
this position.
C.
Power Supply.
A DC voltage
is
supplied from a rectifier-ftlter system.
Unregulated voltage at approximately
+20V
is used for
the
IC101
and
IC102
circuits.
IC101
includes regulated DC
power supply. Regulated DC is supplied
to
the
IC101
and
IC102.
4
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