Circuit Descripiton; Receiver Circuits - Icom IC-R9500 Service Manual Addendum

SECTION 3

3-1 RECEIVER CIRCUITS

BPF UNIT
The received signals from the "HF ANT1" or "HF ANT2"
connector (0.005−29.999 MHz) are passed through the
attenuators and each BPFs for the frequency coverage. The
fi ltered The received signals are applied to the RF-A UNIT
(Refer to "RF-A UNIT").
ANT UNIT
<The received signals from "HF-ANT1">
The received signals from the ANT1 connector (30−1150 MHz)
are amplified or attenuated by pre-amplifier/attenuator. The
amplifi ed signals are applied to the RF-B UNIT (Refer to "RF-B
UNIT").
<The received signals from "ANT2">
The received signals from the ANT2 connector (1150−
3335 MHz) are amplified or attenuated by pre-amplifier/
attenuator. The amplifi ed/attenuated signals are amplifi ed
by one or two RF amplifi ers via band switches, LPFs and
HPFs. The amplifi ed signals are applied to the RF-B UNIT.
(Refer to "RF-B UNIT")
RF-A UNIT
<The received signals from the ANT UNIT>
The received signals from the BPF UNIT are amplifi ed and
fi ltered, then applied to the 1st mixer (IC130), and mixed with
1st LO signals from the PLL UNIT to generate 1st IF signal.
The generated 1st IF signal is fi ltered by one of 1st IF fi lters
( BW=3 kHz, 6 kHz, 15 kHz, 50 kHz or 240 kHz) to remove
unwanted signals. The filtered 1st IF signal is amplified by
1st IF amplifi er, then applied to the 2nd mixer and mixed with
2nd LO signals from the PLL UNIT to generate 2nd IF signal.
The generated 2nd IF signal is amplifi ed by 2nd IF amplifi er,
and passed through the 2nd IF fi lter (BW=50kHz) to remove
unwanted signals. The filtered 2nd IF signal is applied to
the 3rd mixers (D1250 and D1251), and mixed with 3rd LO
signals from the PLL UNIT to generate 3rd IF signal.
The generated 3rd IF signal is amplifi ed by 3rd IF amplifi er
(IC1000), then applied to the MAIN UNIT for demodulation.
• RX DIAGRAM
HF ANT1
0.005–29.999 MHz BPF UNIT
BPF
HF ANT2
0.005–29.999 MHz
BPF
BPF
0.005–
ANT1
ANT UNIT
29.999 MHz
30–1150 MHz
BPF
amp.
ANT2
1150– 3335 MHz
BPF
amp.
CIRCUIT DESCRIPTION
BPF
IC130
BPF
amp.
BPF
RF-A UNIT
BPF
BPF
BPF
BPF
<The received signals from the MIX2 UNIT>
The 2nd IF signal from the MIX2 UNIT is filtered by one
of 2nd IF filters (for BW=3 kHz, 6 kHz, 15 kHz, 50 kHz or
240 kHz) to remove unwanted signals. The filtered 2nd IF
signal is amplified by 2nd IF amplifier, then applied to the
3rd mixer, and mixed with 3rd LO signals from the PLL
UNIT to generate 3rd IF signal.
The generated 3rd IF signal is amplifi ed by 3rd IF amplifi er,
and passed through the 3rd IF fi lter (BW=50kHz) to remove
unwanted signals. The filtered 3rd IF signal is applied to
the 4th mixers (D1250 and D1251), and mixed with 4th LO
signals from the PLL UNIT to generate 4th IF signal.
The generated 4th IF signal is amplifi ed by 4th IF amplifi ers,
then applied to the MAIN UNIT for demodulation.
<WFM mode>
In WFM mode, the IF signal from the 3rd IF amplifier is
amplifi ed by two 3rd IF amplifi ers, and fi ltered by two 3rd IF
fi lters (BW=230 kHz), then applied to the IF IC (IC1031) for
FM-demodulation. The demodulated AF signals are applied
to the MAIN UNIT via AF switch (IC1312).
• AF DEMODULATOR CIRCUITS (WFM)
3rd IF signal
from the 3rd IF amp.
RF-B UNIT
<The received signals from "ANT2">
The received signals from the ANT-2 connector (1150−
3335 MHz) are amplifi ed and fi ltered, then applied to the
1st mixer (MIX1 UNIT; IC301) via band SW (IC1202). (Refer
to "MIX1 UNIT")
<The received signals from "HF-ANT1">
The received signals from the ANT-1 connector (30−
1150 MHz) are filtered by one of BPFs for the frequency
coverage to remove unwanted signals. The filtered The
received signals are amplified by RF amplifiers, filtered
by band fi lters, then applied to the 1st mixer (MIX1 UNIT;
IC301) via band switch (IC1202). (Refer to "MIX1 UNIT")
D600
BPF
amp.
IC21
BPF
amp.
MIX2 UNIT
IC301
BPF
amp.
MIX1 UNIT
amp.
RF-B UNIT
3 - 1
BW=230K BW=230K
Q1011 Q1021
CERAMIC
CERAMI C
IF IF
BPF
AMP BPF AMP
IC1031
IC1030 IC1312
AF signals
IF WFM
SELECT
BUFF
AMP
DET SW to the MAIN UNIT
D1250
amp. to the MAIN UNIT
90°
D1251
amp.
WFM DEMODULATION
WFM
BPF
amp.
Det.
to the MAIN UNIT
3rd IF signal
amp.
AF signal