Icom ID-51E User Manual page 11

1ST IF CIRCUITS
VHF BAND (108–174 MHz)
• Band A (137–174 MHz)
The RX signal from the RF circuit is applied to the 1st mixer
(Q820) and mixed with the 1st LO signal, resulting in the 46.35
MHz 1st IF signal. The converted signal is passed through the
RF SW (D820), 1st IF fi lter (FI3) and limiter (D23), and then
applied to the 1st IF AMP. (Q44). The amplifi ed signal is ap-
plied to the 2nd IF circuit, through the limiter (D22).
• Band B (108–174 MHz)
The RX signal from the RF circuit is applied to the 1st mixer
(Q830) and mixed with the 1st LO signal, resulting in the 61.65
MHz 1st IF signal. The converted signal is passed through the
RF SW (D830), 1st IF fi lter (FI880) and limiter (D880), and
then applied to the 1st IF AMP. (Q901). The amplifi ed signal is
applied to the 2nd IF circuit.
• 1ST IF CIRCUITS
To the 2nd IF circuit (Band A).
To the 2nd IF circuit (Band B).
-Band A:46.35MHz-
D23
D22 FI3
Q44
IF
LIMIT LIMIT
AMP
46.35MHz
-Band B:61.65MHz-
D880
FI880
Q901
IF
LIMIT
AMP
61.65MHz
UHF BAND (380–479 MHz)
• Band A
The RX signal from the RF circuit is applied to the 1st mixer
(Q801) and mixed with the 1st LO signal, resulting in the 46.35
MHz 1st IF signal. The converted signal is passed through the
RF SW (D801), 1st IF fi lter (FI3) and limiter (D23), and then
applied to the 1st IF AMP. (Q44). The amplifi ed signal is ap-
plied to the 2nd IF circuit, through the limiter (D22).
• Band B
The RX signal from the RF circuit is applied to the 1st mixer
(Q811) and mixed with the 1st LO signal, resulting in the 61.65
MHz 1st IF signal. The converted signal is passed through the
RF SW (D811), 1st IF fi lter (FI880) and limiter (D880), and
then applied to the 1st IF AMP. (Q901). The amplifi ed signal is
applied to the 2nd IF circuit.
VCO1 UNIT
1st LO
D801,D820
XTAL RF
BPF SW
D802,D821
A_LO
RF
SW
D811,D830
XTAL RF
BPF SW
D812,D831
B_LO
RF
SW
1st LO
VCO2 UNIT
4 - 2
From the RF circuit (Band A).
Q820
From the RF circuit (Band B).
Q801
Q830
From the RF circuit (Band A).
From the RF circuit (Band B).
Q811