Icom IC-7300 Service Manual page 12

3-2 RF UNIT (continued)
(2) TRANSMIT SIGNAL PROCESSING
The transmit signal from the MAIN UNIT is passed through
one of the BPFs in the filter circuit. The filtered signal level
is adjusted by the gain controller (D1051 and D1052), which
compensates the level difference in the band. The transmit
signal is then amplified by the YGR AMP (IC1031) to obtain
the input level needed in the transmit amplifier circuit.
• RF UNIT (Transmit circuits)
D1051
D1052
D1021 IC1031 D1041
YGR
PIN PIN
ATT
ATT AMP ATT
ALC
ALC
TX signal
RX signal
1.60-74.80 MHz 1.60-30.00 MHz
HPF LPF
RF UNIT
LPF
21.45-33.0 MHz
LPF
33.0-76 MHz
The signal level is also adjusted by the ALC circuit (D1201
and D1041), which is located at the input and output of YGR LPF
AMP (IC1031). The ALC circuit automatically adjusts the
To the RX circuit
transmit signal level according to the transmit power sensing
voltage. The level-adjusted transmit signal is then applied to
the PA UNIT.
0.03-1.59 MHz
LPF
BPF
2.00-2.99 MHz
BPF
3.00-4.49 MHz
BPF
4.50-6.49 MHz
BPF
6.50-7.99 MHz
BPF
8.00-9.99 MHz
BPF
10.00-14.99 MHz
BPF
3-3
Q1411
PRE
AMP
15.00-21.99 MHz
BPF
22.00-29.99 MHz
BPF
30.00-49.99 MHz
54.01-69.99 MHz
BPF
50.00-54.00 MHz(TX)
BPF
70.00-72.00 MHz(TX)
BPF
PHASE
DET
D1201
IC1901
POWER
BUFF
DET
IC1701 D
IMP
DET