Sony ICF-6800W - Filter Functions and Frequency Conversion

ICF-6800W
(1
MHz
units
are
changed
by
VCO2,and
units
First
let
us
take
a
look
at
the
characteristics
less
than
1
MHz
are
changed
by
the
VFO.)
of
the
mixer.
This
will
tell
us
the
following.
In
the
case
of
a
15.5
MHz
signal,
the
different
When
signal
A
which
is
of
a
certain
frequency
frequencies
are
as
follows:
is
mixed
with
signal
B
which
is
of
a
different
VCO1:
19.055
MHz
+
15.5
MHz
=
34.555
MHz
frequency,
the
following
signals
are
produced.
VCO2:
28
MHz
+
5
MHz
=
33
MHz
Frequency
of
A:
fg
Frequency
of
B:
fy
VFO: 1.055 MHz + 0.5 MHz = 1.555 MHz 1. fo-fy
c.
Functions
of
filters
2.
a.
+f]
Fig. 7 is essentially the block diagram shown . Po
- Ty
in Fig. 5 to which the frequencies of each
of the sections are indicated when receiving
1 MHz, 10 MHz, and 20 MHz signals.
When receiving a 10 MHz signal, the output of
mixer 2 becomes 8.945 MHz and is then fed to
the phase comparator.
However, the oscillating frequencies of the
VFO range from 0.975 MHz to 2.075 MHz; it is
These frequencies are fed out from the output
of the mixer.
The following frequencies are fed out from the
output of the mixer 2 when receiving a 10 MHz
signal as indicated in Fig. 7.
1. 10 MHz — 1.055MHz = 8.945 MHz
. 10 MHz + 1.055 MHz = 11.055 MHz
2
not capable of oscillating as high as 8.945 MHz. 3. 10 MHz
This would make it seem impossible to receive 4. 1.055 MHz
a 10 MHz signal. However, this is not the case;
a signal like this is received in the following
manner.
INPUT FROM es
ANTENNA
1 MHz
(10 MHz)
[20 MHz]
20.055 MHz
(29.055 MHz}
(39.055 MHz)
8.945 MHz 1.055 MHz
(1.055
MHz)
(8.945
MHz}
(11.055
MHz)
[1.055
MHz]
PHASE
COMPARATOR
29 MHz
(28 MHz}
[28 MHz]
VARIED IN 1 MHz STEP
BY “SW BAND SELECTOR”
28 MHz AT “0”
1.055 MHz
(8.945 MHz)
[1.055 MHz]
29 MHz AT “1”
37 MHz AT “9”
7.055 MHz
8945 MHz
71.055 MHz
10 MHz
1.055 MHz
1.055 MHz 3.5 MHz
LPF Curve