Circuit Descripiton; Receiver Circuits - Icom IC-9100 Service Manual

SECTION 3.

3-1 RECEIVER CIRCUITS

HF RF CIRCUITS
ANTENNA SWITCHING CIRCUITS (CTRL UNIT)
RX signal from the antenna connector [ANT1] (J1) or [ANT2]
(J2) is passed through the antenna switch (RL501), current
detector (D401, L401), tuner switches (RL301 and RL351),
RX line switches (RL601 and RL621) and LPF, and then
applied to the BPF UNIT.
ATTENUATOR CIRCUITS (BPF UNIT)
The RX signal from the CTRL UNIT is passed through
or bypassed the attenuator circuit (RL141, R141–R143),
depending on the setting.
The RX signal, which is passed though or bypassed the
attenuator circuit (RL141, R141–R143), is applied to the
BPF circuits.
• HF RF CIRCUITS
Q511/Q512
PRE
AMP
Q532
PRE
AMP
To the 1st RX IF circuits
CIRCUIT DESCRIPTION
0.03-1.6 MHz
LPF ATT
1.6-2.0 MHz
RL141
BPF HPF
2.0-4.0 MHz
BPF
4.0-8.0 MHz
BPF
8.0-11.0 MHz
BPF
11.0-15.0 MHz
BPF
15.0-22.0 MHz
BPF
22.0-30.0 MHz
BPF
50.0-54.0 MHz
BPF UNIT
BPF
30.0-50.0 MHz
54.0-60.0 MHz
BPF
3 - 1
BPF CIRCUITS (BPF UNIT)
The RX signal from the attenuator circuits is passed
through an LPF or one of BPFs, depending on the operating
frequency, to remove unwanted out-of-band signals.
The filtered RX signal is applied to or bypassed the
preamplifi er circuits.
PREAMPLIFIER CIRCUITS (BPF UNIT)
The RX signal from the BPF circuits is applied to or
bypassed the preamplifi er.
When the Preamplifier function is activated, the RX signal is
amplifi ed by one of preamplifi ers (Q511, Q512 (for 1.8–2.1 MHz)
or Q532 (for 24–50 MHz)).
The amplifi ed or bypassed RX signal is applied to the RF-A
UNIT.
HF ANT2
HF ANT1
RL501
D401
CURRENT
DET
RL351
NETWORK
UNIT
TUNING
NETWORK
RL301
RL601
RL621
LPF
CTRL UNIT