Circuit Descripiton; Receiver Circuits - Icom IC-E92D Service Manual

SECTION 4

4-1 RECEIVER CIRCUITS

RF CIRCUITS (RF UNIT)
RX signals from the antenna are sorted by its frequency by
the filters and gone through RF circuits for each bands. And
this transceiver also has two RX lines for two independent
operating bands; A BAND and B BAND.
<A BAND>
• 76 MHz and below
The RX signals are passed through two LPFs, ANT SW,
ATT, band SW and LPF. The RX signals are sorted by its
frequency by band SWs.
• 0.495–29.995 MHz
The RX signals are passed through the band SW (D201)
and LPF, and applied to tuned RF AMP (Q200). The
amplified RX signals are applied to the 1st mixer (IC900) via
the band SW (D203).
• 30–75.995 MHz
The RX signals are passed through the band SW (D250)
and tuned BPF, and applied to the RF AMP (Q250). The
amplified RX signals are passed through tuned BPF, then
applied to the 1st IF mixer (IC900) via the band SW (D256).
• 76–117.995 MHz
The RX signals are passed through two LPFs, ANT SW, ATT,
band SW, LPF and another band SW in sequence, then applied
to the RF AMP (Q300) via the tuned BPF. The amplified RX
signals are passed through another tuned BPF, then applied to
another RF AMP (Q301). The amplified RX signals are applied
to the 1st mixer (IC900) via the band SW (D311).
• RF CIRCUITS
D203
BAND
To 1st mixer
SW
(IC900)
for A BAND
D256 D254,255
BAND
BPF
SW
Q301
D311
D306-309
BAND RF
SW AMP
D405
RF
SW
D454
RF
SW
To 1st mixer
(IC50)
for B BAND
D508
RF
SW
D606
D604,605
BAND
BPF
SW
D655
D653,654
BAND
BPF
SW
D706
Q701
BAND RF
SW AM P
CIRCUIT DESCRIPTION
L202,203
Q200
C205-9
D202
RF
LPF
AMP
D251
Q250
D252
D253
RF
BPF
AMP
Q300
D304,305
D310
RF
BPF BPF
AMP
Q401
D402,403
D404
RF
BPF
AMP
B:118−174MHz
Q450
D451,452
D453
RF
BPF
AMP
D504,507
Q501
RF
BPF
AMP
A:350−470MHz
Q601
D601,602
D603
RF
BPF
AMP
Q651
D650,651
D652
RF
BPF
AMP
Q700
D703,704
D705
RF
BPF
AMP
• 118–173.995 MHz
The RX signals are passed through two LPFs, ANT SW,
ATT and band SW, then applied to the RF AMP (Q400). The
amplified RX signals are passed through the tuned BPF,
and applied to another RF AMP (Q401). The amplified RX
signals are passed through tuned BPF, then applied to the
1st IF mixer (IC900) via the band SW.
• 174–259.995 MHz
The RX signals are passed through the LPF, HPF, ANT SW,
ATT, band SW, HPF and another band SW insequence,
then applied to the RF AMP (Q300) via the tuned BPF. The
amplified RX signals are passed through another tuned BPF,
then applied to another RF AMP (Q301). The amplified RX
signals are applied to the 1st mixer (IC900) via the band SW.
• 260–349.995 MHz and 470–599.995 MHz
The RX signals are passed through the LPF, HPFANT SW,
ATT, BAND SW and tuned BPF in sequence, then applied to
the RF AMP (Q500). The amplified RX signals are passed
through another 2pole tuned BPF, and applied to another
RF AMP (Q501). The amplified RX signals are then applied
to the 1st mixer (IC900) via the band SW.
• 350–469.995 MHz
The RX signals are passed through the LPF, HPF, ANT
SW, ATT, band SW and HPF in sequence, then applied to
the RF AMP (Q600). The amplified RX signals are passed
through the tuned BPF, and applied to the RF AMP (Q601).
The amplified RX signals are passed through the BPF, then
applied to the 1st mixer (IC900) via the band SW.
A:0.5−30MHz
L200,201
D201
C201-204
D200
BAND
BAND
LPF
SW SW
D250
BAND
A:30−76MHz
SW
A:174−260MHz
L302,303
C306-310
D303 D302
BAND BAND
HPF
SW SW
A:76−118MHz
L300,301
D301 C301-305 D300
BAND BAND
LPF
SW SW
A:118−174MHz
D401 Q400 D400
RF BAND
BPF
AMP SW
D450
BPF
A:260−350MHz
A:470−600MHz
Q500
D500
D501,502
D503
RF BAND
BPF
AMP SW
A:350−470MHz
L600,608
Q600 C600-602,630,631 D600
RF BAND
HPF
AMP SW
B:350−470MHz
D702 D 701 D700
RF
BPF ATT
SW
4 - 1
Tx:144.000−148.000MHz
L4,C7-9
D9
ANT
ATT LPF
SW
Q1,3,D6-8
L5-7
C10-14
D5
ANT
HPF
ATT
SW
Q1,2,150
Tx:430.000−450.000MHz
D1,3,4,10,151,160
L8,9 A:600−1000MHz
C18-20
HPF
L1-3
C1-6
LPF