Icom IC-F8101 Service Manual page 16

2ND TX IF CIRCUIT (MAIN-A UNIT)
The 2nd TX IF signal from the 3rd TX IF circuits is applied
to the 2nd TX IF mixer (D1812, D1813), to be mixed with
the 2nd TX LO signal, resulting in the 64.455 MHz 1st TX IF
signal.
The 1st TX IF signal is passed through the 1st TX IF filter
(FI1401), amplified by the 1st TX IF AMP (Q1409), and then
applied to the 1st TX IF circuits.
1ST TX IF CIRCUIT (MAIN-A UNIT)
The 1st TX IF signal from the 2nd TX IF circuits is applied
to the 1st TX IF mixer (IC1401), to be mixed with the 1st TX
LO signal, resulting in the TX signal (TX frequency itself).
The converted TX signal is applied to the filter circuits,
through the buffer (Q1401).
• 2ND AND 1ST TX IF CIRCYUIT
64.455MHz 1st TX IF
D1812 FI1401
D1813
D1410 D1407
XTAL
From the 3rd
BPF
TX IF circuits
15 kHz
2nd TX LO signal
• FILTER, TX AMPLIFIER AND LPF CIRCUITS
D 1 1 2
D1133
D1131
From the 2nd
TX IF circuits
D1121
D1122
D1123
D1124
D1125
D1126
D1127
TX frequency
Q1409 Q1401
IC1401
D1404 D1401
IF
To the filter
BUFF
AMP
circuits
D1402
1st TX LO signal
0.03-1.59 MHz
0
D 1 1 1 2
LPF
D1111
1.60-2.49 MHz
D1113 D1106
BPF HPF
2.50-3.99 MHz
D1114
BPF
4.00-5.99 MHz
D1115
BPF
6.00-8.99 MHz
D1116
BPF
LPF
9.00-12.99 MHz
D1117
BPF
13.00-19.99 MHz
D1118
BPF
20.00-29.99 MHz
D1119
BPF
FILTER CIRCUIT (MAIN-A UNIT)
The TX signal from the 1st TX IF circuits is passed through
the one of BPFs, depending on the operating frequency, to
remove unwanted signals contained in the TX signal.
The filtered TX signal is amplified by the YGR AMP
(IC1101), and then applied to the PA-A UNIT.
TX AMPLIFIER CIRCUIT (PA-A UNIT)
The TX signal from the MAIN-A UNIT is applied to the RF
AMP (Q4002), through the LPF (L4002, C4008, C4014).
The amplified TX signal is sequentially amplified by the pre-
drive AMP (Q4003), drive AMP (Q6851), and power AMP
(Q4006, Q4007).
The amplified TX signal is applied to the PA-A UNIT.
LPF CIRCUIT (PA-A UNIT)
The amplified TX signal from the power AMP (Q4006,
Q4007) is passed through one of LPFs, depending on the
transmitting frequency, to remove harmonic components
contained in the TX signal.
The filtered TX signal is applied to the antenna, through the
TX/RX line SW (RL5001) and SWR detect circuit (D5001,
D5002).
IC1101
YGR
AMP
MAIN-A UNIT
Q4006,
Q4002 Q 4 0 0 3 Q6851 Q4007
RF
PRE PWR
DRIVE
DRIVE
AMP
AMP AMP
PA-A UNIT
4-3
1.6-2.3 MHz
RL5012
RL5011
LPF
2.3-3.3 MHz
RL5021 RL5022
LPF
3.3-4.9 MHz D5001
D5002
RL5031 RL5032
LPF
SWR
DET
4.9-7.0 MHz
RL5041 RL5042
LPF
7.0-10.0 MHz
RL5051 RL5052 RL5001
RX
LPF
TX
10.0-14.5 MHz
RL5061 RL5062
LPF
14.5-21.0 MHz
RL5071 RL5072
LPF
21.0-30.0 MHz
RL5081 RL5082
LPF