4 - 2
• 600–999.990 MHz
The RX signals are passed through the HPF, band SW, ATT
and tuned BPF in sequence, then applied to the RF AMP
(Q700). The amplified RX signals are passed through the
BPF, and applied to another RF AMP (Q701). The amplified
RX signals are applied to the 1st mixer (IC900) via the band
SW.
The RF attenuation which reduces RX signal level to –10 dB is
carried out by D5, D9 and D701, by turning these PIN diodes
ON using "ATT" signal.
1ST IF CIRCUIT (MAIN UNIT)
<A BAND>
The RX signals from the RF circuits are applied to the 1st
mixer (RF: IC900) to be converted into the 1st IF signal,
by being mixed with the 1st Local Oscillator (LO) signals
from the VCO UNIT. The 1st LO signals from the VCO UNIT
are applied to the 1st mixer via the LO SW, or doubler (in
receiving of 600 MHz and above).
The converted 1st IF signal is passed through the IF SW (D2)
which toggles the path of the 1st IF signaL: WFM mode or
other than WFM mode.
• FM/AM MODE
The 1st IF signal from the 1st mixer (RF: IC900) is entered
to the MAIN UNIT, and passed through the 1st IF filter (FI1)
via IF SWs (D2, 3) to remove unwanted signals. The filtered
1st IF signals are applied to the 1st IF AMP (Q100), and the
amplified 1st signal is applied to the 2nd IF circuit.
<B BAND>
• 118–173.995 MHz
The RX signals for B BAND are passed through 2 LPFs,
ANT SW, ATT and band SW, then applied to the RF AMP
(Q400). The amplified RX signals are passed through
the BPF, and applied to the tuned RF AMP (Q450). The
amplified RX signals are passed through tuned 2-pole BPF,
then applied to the 1st mixer (M: IC50) via the band SW.
• 350–469.995 MHz
The RX signals are passed through the LPF, HPF, ANT SW,
ATT, band SW and another HPF in sequence, then applied
to the RF AMP (Q600). The amplified RX signals are
passed through 2-pole tuned BPF, and applied to tuned RF
AMP (Q651). The amplified RX signals are passed through
another tuned BPF, then applied to the 1st mixer (M: IC50)
via the band SW.
• WFM MODE (Incl. 2nd IF circuit)
When receiving in WFM mode, the 1st IF signal from the 1st
mixer (RF: IC900) is entered to the MAIN UNIT and passed
through the BPF, then applied to the 1st IF AMP (Q1). The
amplified 1st IF signal is applied to the 2nd mixer (Q2) to
converted into the 13.35 MHz 2nd IF signal, by being mixed
with the 45.9 MHz 2nd LO signal (generated by X450,
tripled by Q451). The converted 2nd IF signal is passed
through the 2nd IF filter (FI2) to remove sideband noise,
then applied to the 2nd IF AMP (Q100) via the IF SW (D3).
The amplified 2nd IF signal is applied to the 3rd IF circuit.
Q1
R18
Q2
C6
D2
R14
C29
C8
C17
C24
C10
D10
R11
C12
R25
D3
R15
L10
C19
FI1
1
IN
2
OUT
3
GND
4
GND
5
6
C3
R8
C20
0.01
C102
C30
C16
C792
R9
5
L1
0.01
C9
C5
R17
6.8K
R101
R10
R6
FI2
I
O
C13
C7
L30
R23
8
00
R7
C18
C4
1st IF filter
2nd mixer
2nd IF filter
1st IF AMP
FM/AM mode
WFM mode
1st IF filter
<B BAND>
The RX signals from the RF circuits are entered to the MAIN
UNIT, and applied to the 1st mixer (IC50) to be converted
into the 1st IF signal, by being mixed with the 1st Local
Oscillator (LO) signals from the B BAND VCO (Q350, 351)
via the buffer (Q353). The converted 1st IF signal is passed
though the 1st IF filter (FI50) to remove unwanted signals,
then applied to the 1st IF AMP (Q200). The amplified 1st IF
signal is applied to the 2nd IF circuits.
C51
C50
C54
X200
R202
C52
R201
R209
C205
C206
C58
Q200
C207
C60
FI50
1
IN
2
OU T
3
GND
4
GND
5
6
C208
C204
R52
R51
L200
R205
EP50
C203
C57
IC50
1
RFI
2
GND
3
LO
4
PS
5
VCC
6
IFO
C59
L50
1st IF filter
1st mixer
1st IF AMP
BAND
RX MODE
1st IF
1st LO
2nd IF
2nd LO
3rd IF
3rd LO
A BAND
NFM/AM
61.65 MHz
62.15–538.345 MHz (<600 MHz)
269.175–469.17 MHz (>600 MHz)
450 kHz
61.2 MHz
-
-
WFM
59.25 MHz
16.75–355.375 MHz(76–770 MHz)
13.35 MHz
45.9 MHz
1.95 MHz
15.3 MHz
B BAND
NFM/AM
46.35 MHz
71.65–423.65 MHz
(118–174, 350–470 MHz)
450 kHz
45.9 MHz
-
-
• FREQUENCY CONFIGULATION
• 1ST IF CIRCUIT (For FM/AM mode) AND 2ND IF CIRCUIT (For WFM mode) (A BAND)
• 1st IF CIRCUIT (B BAND)
