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ll. Block Diagram
Figure 2 is a chart of the reception frequency, local oscillator frequency and intermediate frequency for each
band.
Intermediate
Local Osc.
Frequency (MHz)
Frequency (MHz)
Frequency (MHz)
10.7
98.2 ~
118.7
LW
0.150
~ 0.410
0.605 ~
0.865
8.0 ~ 16.0
2.
|
10.0
16.0 ~ 30.0
2
|
18.0
Fig. 2
Because, the upper local oscillator frequency is used the conversion signal is subtracted from the counter circuit
for each band.
As can be understood from the table in figure 2, an intermediate frequency of 10.7 MHz is used for the FM band.
Because the upper local oscillator frequency is used, the reception frequency is displayed after 10.7 MHz has
been subtracted from the local oscillator frequency.
For the LW, MW bands, 455 kHz is subtracted from the local oscillator frequency.
For the SW bands, 2 MHz is subtracted from the local oscillator frequency.
Figures 3 and 4 are block diagrams which include the RF, Local Oscillator, IF and Counter circuits.
The subtraction is accomplished through logic signals applied to pins 3, 4, 5 and 6 of IC902.
ANT
F
RF AMP
IF
;
\F AMP
'
IF AMP
LOCAL OSC
C101
Q103
3 1101
COUNTER
COUNTER
BUFFER
e164
PRE-AMP
(3)
River
AM CIRCUIT
Q901,0902
1C901
0000
FM Circuit
0
O
©
O
AMP
(2) Ree
DISPLAY
O si7
Q907
1c902
2)
Swt/Swe/Sw3
TUNING CIRCUIT
L410,L109, L108
CIRCUIT
£102
EP
NOTE:
1.8902 terminal Nos. 3.4.5,6:for Preset
L. condition
in terminals 3,4..5 and-6):—10.7MHz
2. $1:Band Selector
FMLW/MW/SW1/SW2/SW3
Fi ig. 3
FM Section Block Diagram
shown
at FM
position
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