1St If Circuits (Main Unit); 2Nd If Circuits (Main Unit) - Icom ID-5100E Service Manual

1ST IF CIRCUITS (MAIN UNIT)

• Band A
The RX signal from the RF circuit is applied to the 1st mixer
(IC125) and mixed with the 1st LO signal, resulting in the
38.85 MHz 1st IF signal. The converted signal is passed
through the 1st IF fi lter (FI105), and then applied to the 1st
IF AMP (Q138). The amplifi ed signal is applied to the 2nd IF
circuit, through the limiter (D114).
• 1ST IF CIRCUITS (Band A)
D114
2nd IF
circuit
LIMITER
Q138/
D116/D118
• Band B
The RX signal from the RF circuit is applied to the 1st mixer
(IC124) and mixed with the 1st LO signal, resulting in the
46.35 MHz 1st IF signal. The converted signal is passed
through the 1st IF fi lter (FI104), and then applied to the 1st
IF AMP (Q137). The amplifi ed signal is applied to the 2nd IF
circuit, through the limiter (D113).
• 1ST IF CIRCUITS (Band B)
D113
2nd IF
circuit
LIMITER
Q137/
D115/D117
Band A
1st LO
FI105
LIF
IF XTAL
AMP BPF
IC125
38.85MHz
Band B
1st LO
FI104
RIF
IF XTAL
AMP BPF
IC124
46.35MHz

2ND IF CIRCUITS (MAIN UNIT)

• Band A
The 1st IF signal from the 1st IF circuit is applied to the IF IC
(IC121, pin 20), which contains the 2nd IF AMP, 2nd mixer,
FM demodulator, and so on.
The 1st IF signal is mixed with the 38.4 MHz 2nd LO signal,
resulting in the 450 kHz 2nd IF signal. The converted signal
is passed through the external 2nd IF fi lter (FM mode: FI103,
FM-N or DV mode: FI102) to remove sideband noise.
While operating in the FM or AM mode, the fi ltered signal is
amplifi ed by the 2nd IF AMP, and then demodulated by the
internal demodulator circuit. The demodulated signal is ap-
plied to the RX AF circuit, through the RX mode SW (IC119),
AF fi lter (Q113 and Q140) and AF SW (IC111).
While operating in the DV mode, the fi ltered signal is ampli-
fi ed by the 2nd IF AMP, and then demodulated by the inter-
nal demodulator circuit. The demodulated signal is applied
to the digital demodulation circuit, through the RX mode SW
(IC119) and buffer AMP (IC117).
• 2ND IF CIRCUITS (Band A)
Digital
demodulation
IC117
Cricut
DV
BUFF
IC111 Q113/Q140
RX AF
Cricut
FM/AM
DIGI/AN AF
AFMUTE FIL
• Band B
The 1st IF signal from the 1st IF circuit is applied to the IF IC
(IC120, pin 20), which contains the 2nd IF AMP, 2nd mixer,
FM demodulator, and so on.
The 1st IF signal is mixed with the 45.9 MHz 2nd LO signal,
resulting in the 450 kHz 2nd IF signal. The converted signal
is passed through the external 2nd IF fi lter (FM mode: FI101,
FM-N or DV mode: FI100) to remove sideband noise.
While operating in the FM or AM mode, the fi ltered signal is
amplifi ed by the 2nd IF AMP, and then demodulated by the
internal demodulator circuit. The demodulated signal is ap-
plied to the RX AF circuit, through the RX mode SW (IC119),
AF fi lter (Q112 and Q139) and AF SW (IC111).
While operating in the DV mode, the fi ltered signal is ampli-
fi ed by the 2nd IF AMP, and then demodulated by the inter-
nal demodulator circuit. The demodulated signal is applied
to the digital demodulation circuit, through the RX mode SW
(IC119) and buffer AMP (IC117).
• 2ND IF CIRCUITS (Band B)
Digital
IC117
demodulation
Cricut
BUFF
IC111 Q112/Q139
RX AF
Cricut
FM/AM
DIGI/AN AF
AFMUTE
FIL
4-2
Q200
Band A
38.4MHz 12.8MHz
X3
IC119
AM
DET OUT
IF IC
FM
SELECT
Q122/Q124/Q142
WIDE/NARROW
Q128/D107/D108
SELECTOR
D111/D112
CERAMIC CERAMIC
BPF BPF
FI102 FI103
Band B
Q220
15.3MHz
45.9MHz
X3
IC119
AM
DV
DET OUT
IF IC
SELECT
FM
WIDE/NARROW
SELECTOR
Q121/Q123/Q141
Q127/D105/D106
D109/D110
CERAMIC
CERAMIC
BPF BPF
FI100 FI101
X200
IC121
X102
X201
IC120
X101