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4 - 1
SECTION 4
CIRCUIT DESCRIPTION
4-1 RECEIVER CIRCUITS
RF CIRCUITS
<Left band>
• 118−174 MHz
The received signals from the antenna connector ANT-1
(J1) are passed through two LPFs (L101, 104, 108, C342,
346; L88, 92, 96, C318, 326, 330), then applied to the RF
amplifi er (Q37) via TX/RX switch (D75). The amplifi ed signals
are passed through the RX switch (RL2), attenuator (D68)
and tuned BPF (D55, 66), before being applied to another
RF amplifi er (Q33). The amplifi ed signals are applied to the
1st mixer (IC19) via the another tuned BPF (D41, 44) and
RX switch (D38).
While the diversity operation is activated, the received
signals are also input from ANT-2 (J2). The received signals
are passed through two LPFs (L103, 106, 109, C344, 348;
L90, 93, 98, C319, 327, 348), antenna switch (D65, 72) and
limitter (D64, 67), then applied to the RF amplifi er (Q39).
The amplified signals are applied to the RX switch (RL2),
and gone through the same process as the received signals
from ANT-1 (J1).
• 174−260 MHz
The received signals from the antenna connector (J1) are
passed through two RX switches (RL3 and D56) and the
tuned BPF (D51), then applied to the RF amplifier (Q34).
The amplified signals are passed through the BPF (D45),
attenuator (R139, 144, 147) and RX switch (D36) before
being applied to the 1st mixer (IC19).
• 260−375 MHz
The received signals from the antenna connector (J1) are
passed through two RX switches (RL3 and D57) and the
tuned BPF (D50), then applied to the RF amplifi er (Q35).
The amplifi ed signals are passed through the BPF (D465),
attenuator (R142, 143, 150) and RX switch (D37) before
being applied to the 1st mixer (IC19).
• 375−550 MHz
The received signals from the antenna connector (J1) are
passed through the LPF (L101, 104, 108, C342, 346) and
HPF (L77, 80, C296, 297, 303, 308), then applied to the
RF amplifier (Q28) via TX/RX switch (D53, 61, 62). The
amplifi ed signals are passed through the RX switch (RL1),
attenuator (D28) and tuned BPF (D19, 21, 24, 27), before
being applied to another RF amplifi er (Q20). The amplifi ed
signals are applied to the 1st mixer (IC19) via the another
tuned BPF (D11, 13, 15, 17) and RX switch (D8).
While the diversity operation is activated, the received
signals are also input from antenna connector ANT-2 (J2).
The received signals are passed through the LPF (L103,
106, 109, C344, 348), HPF (L95, 99, C329, 333, 338),
antenna switch (D69, 73, 74) and limitter (D63, 66), then
applied to the RF amplifi er (Q29).
The amplified signals are applied to the RX switch (RL1),
and gone through the same process as the received signals
from ANT-1 (J1).
RF
AMP
RX
SW
LPF
HPF
ATT
RX
SW
ATT
BPF
ATT
RX
SW
HPF
RF
AMP
ATT
RF
AMP
BPF
ATT
RF
AMP
LPF
ANT
SW
BPF
RF
AMP
BPF
RF
AMP
RX
SW
LPF
RF
AMP
BPF
RF
AMP
LPF
BPF
ATT
RF
AMP
HPF
BPF
BPF
RX
SW
BPF
BPF
RX
SW
BPF
RF
AMP
RX
SW
RX
SW
RF
AMP
TX/RX
SW
RX
SW
HPF
ATT
RX
SW
ANTENNA
ATT
RX
SW
RX
SW
RX
SW
ANT
SW
BPF
ANTENNA
RF
AMP
D62
TX/RX
SW
D59
D77
D75
D61
D53
LIMIT
D10,
D32
D8
D64,D67
D11
D58
RL1
D14,
D76
Q29
D60
Q28
D38
D16
D70
,D13,
D65,D71,D72
D23,
Q38
D28
D19,
D55,
Q37
D24,
RL2
Q30
D17
D63,D66
D18,
Q20
D30
Q32
D48,D49
D15,
D12,
LIMIT
375−550 MHz
D40,
D78,
LIMIT
375−550 MHz
D69,D73,D74
D44
D35
D26
118−174 MHz
D7
118−174 MHz
Left band
Right band
D41,
D27
D68
Q39
D43
LIMIT
D20,
D54,
Q33
810−1000 MHz
D37
D51
Q18
D50
D46
D45
Q35
D80
D22
D9
Q40
D36
Q23
Q34
174−260 MHz
260−375 MHz
RL3
D57
D56
D79
Q19
D21,
• RF CIRCUITS