D102 - Icom IC-E92D Service Manual

• 600–999.990 MHz
The RX signals are passed through the HPF, band SW, ATT
and tuned BPF in sequence, then applied to the RF AMP
(Q700). The amplified RX signals are passed through the
BPF, and applied to another RF AMP (Q701). The amplified
RX signals are applied to the 1st mixer (IC900) via the band
SW.
The RF attenuation which reduces RX signal level to –10 dB is
carried out by D5, D9 and D701, by turning these PIN diodes
ON using "ATT" signal.
• FREQUENCY CONFIGULATION
BAND RX MODE
NFM/AM
A BAND
WFM
B BAND NFM/AM
1ST IF CIRCUIT (MAIN UNIT)
<A BAND>
The RX signals from the RF circuits are applied to the 1st
mixer (RF: IC900) to be converted into the 1st IF signal,
by being mixed with the 1st Local Oscillator (LO) signals
from the VCO UNIT. The 1st LO signals from the VCO UNIT
are applied to the 1st mixer via the LO SW, or doubler (in
receiving of 600 MHz and above).
The converted 1st IF signal is passed through the IF SW (D2)
which toggles the path of the 1st IF signaL: WFM mode or
other than WFM mode.
• FM/AM MODE
The 1st IF signal from the 1st mixer (RF: IC900) is entered
to the MAIN UNIT, and passed through the 1st IF filter (FI1)
via IF SWs (D2, 3) to remove unwanted signals. The filtered
1st IF signals are applied to the 1st IF AMP (Q100), and the
amplified 1st signal is applied to the 2nd IF circuit.
• 1ST IF CIRCUIT (For FM/AM mode) AND 2ND IF CIRCUIT (For WFM mode) (A BAND)
00
8
R10
R101
6.8K
D3
5
C9
C17
0.01
O
R11
C102
2nd IF filter
0.01
<B BAND>
The RX signals from the RF circuits are entered to the MAIN
UNIT, and applied to the 1st mixer (IC50) to be converted
into the 1st IF signal, by being mixed with the 1st Local
Oscillator (LO) signals from the B BAND VCO (Q350, 351)
• 1st IF CIRCUIT (B BAND)
C204
R209
C205
X200
R205
C206
1st IF AMP
C207
C208
1st IF
62.15–538.345 MHz (<600 MHz)
61.65 MHz
269.175–469.17 MHz (>600 MHz)
59.25 MHz 16.75–355.375 MHz(76–770 MHz)
71.65–423.65 MHz
46.35 MHz
(118–174, 350–470 MHz)
1st IF filter
C24
FI1
4 1
R9 GND IN
C8
2 3
OUT GND
C7
C6
FI2
R23
C16 R17
I
Q2
R18
2nd mixer
L200
R201
C59 R52
Q200
C58
R202
C203
<B BAND>
• 118–173.995 MHz
The RX signals for B BAND are passed through 2 LPFs,
ANT SW, ATT and band SW, then applied to the RF AMP
(Q400). The amplified RX signals are passed through
the BPF, and applied to the tuned RF AMP (Q450). The
amplified RX signals are passed through tuned 2-pole BPF,
then applied to the 1st mixer (M: IC50) via the band SW.
• 350–469.995 MHz
The RX signals are passed through the LPF, HPF, ANT SW,
ATT, band SW and another HPF in sequence, then applied
to the RF AMP (Q600). The amplified RX signals are
passed through 2-pole tuned BPF, and applied to tuned RF
AMP (Q651). The amplified RX signals are passed through
another tuned BPF, then applied to the 1st mixer (M: IC50)
via the band SW.
1st LO 2nd IF
450 kHz
13.35 MHz
450 kHz
• WFM MODE (Incl. 2nd IF circuit)
When receiving in WFM mode, the 1st IF signal from the 1st
mixer (RF: IC900) is entered to the MAIN UNIT and passed
through the BPF, then applied to the 1st IF AMP (Q1). The
amplified 1st IF signal is applied to the 2nd mixer (Q2) to
converted into the 13.35 MHz 2nd IF signal, by being mixed
with the 45.9 MHz 2nd LO signal (generated by X450,
tripled by Q451). The converted 2nd IF signal is passed
through the 2nd IF filter (FI2) to remove sideband noise,
then applied to the 2nd IF AMP (Q100) via the IF SW (D3).
The amplified 2nd IF signal is applied to the 3rd IF circuit.
C29
R7
R8
C4
C5
1st IF AMP
C13
R15
L1
C792
Q1
D10
R25
C12
via the buffer (Q353). The converted 1st IF signal is passed
though the 1st IF filter (FI50) to remove unwanted signals,
then applied to the 1st IF AMP (Q200). The amplified 1st IF
signal is applied to the 2nd IF circuits.
1st IF filter
EP50
FI50
C54
R51
4 1
GND IN
2 3
OU T GND
C52
C57
4 - 2
2nd LO 3rd IF
61.2 MHz -
45.9 MHz 1.95 MHz 15.3 MHz
45.9 MHz -
D2
FM/AM mode
WFM mode
1st IF filter
C18
C10 C30
L10
C20
C19
L30
R14
1st mixer
C60
IC50
C50
IFO RFI
6 1
VCC GND
5 2
PS LO
4 3
C51
L50
3rd LO
-
-
C3
R6