Icom IC-R9500 Service Manual Addendum page 241

MIX1 UNIT
The received signals from the RF-B UNIT are mixed with 1st
LO signals from the PLL UNIT, to generate 1st IF signal. The
generated 1st IF signal is applied to the RF-B UNIT again,
then fi ltered by 1st IF fi lter, and amplifi ed by 1st IF amplifi er
before being applied to the 2nd mixer (MIX2 UNIT; IC21)..
(Refer to "MIX2 UNIT")
MIX2 UNIT
The 1st IF signal from the RF-B UNIT is converted into the
2nd IF signal at 2nd mixer (IC21) by mixing with 2nd LO
signal (2LO) from PLL UNIT. The converted 2nd IF signal
is applied to the RF-A UNIT. (Refer to "RF-A UNIT <The
received signals from the MIX2 UNIT>")
CONNECT-B UNIT (AF AMPLIFIER CIRCUITS)
The AF signals from the MAIN UNIT are applied to the AF amplifi er (IC41) via the squelch gate (Q91). The amplifi ed signals are
passed through the VCA (Voltage Controlled Attenuator; IC21) for audio output level adjustment. The level adjusted AF signals
are output from ext. speaker after being amplifi ed by AF power amplifi er (IC11), or output from internal speaker/phones after
being power-amplifi ed by AF power amplifi er (IC81).
• AF CIRCUITS
Demodulated AF signals
from the MAIN UNIT
SCOPE/TV UNIT
-SPECTRUM SCOPE SCREEN-
A potion of the IF* signal from the RF-A UNIT is passed through the splitter, and, amplifi ed by IF* amplifi ers and fi ltered, then
converted into the another IF* signal at the mixer. The converted IF* signal is fi ltered and amplifi ed by X'tal fi lter and IF amplifi ers,
then applied to the mixer to be converted again. The converted IF* signal is amplifi ed and buffer amplifi ed, then applied to the
MAIN UNIT via LPF.
The IF* signal from the SCOPE/TV UNIT is amplifi ed, and applied to the A/D converter, to be converted to the digital signal. The
converted digital signal is applied to the scope DSP IC and processed to convert its data format for spectrum scope screen.
• SCOPE CIRCUIT
1st/2nd IF signal
SPLITTER
from the RF-A UNIT
IF signal
to the video AM-demodulation circuit
*; 1st IF for 0.005−29.999 MHz signals. 2nd IF for 30−3335 MHz signals.
IC21
VCA
Q91
IC41
CONNECT-B UNIT
SQL AF
GATE AMP
Q22
LPF
AF
AMP
IC41
Q1051
Q1001
IC1101
IF IF
BPF
AMP AMP
2nd/3rd LO signal
from the OSC UNIT
MAIN UNIT (AUDIO DEMODULATION)
The 3rd/4th IF signal from the RF-A UNIT is applied to the A/
D converter (IC1305) via buffer, and converted into the digital
audio signal. The converted digital audio signal is applied to
the DSP IC (IC1005) and processed. The processed digital
audio signal is converted into the analog audio signals at the
D/A converter (IC1401), then applied to the AF amplifi er of
the CONNECT-B UNIT via LPF.
• AF DEMODULATOR CIRCUITS (other than WFM)
IC1302
3rd IF signal
SW
from RF-A UNIT
IC1005
RX
DSP
FRONT UNIT
Q21
IC81
AF
LPF
AMP
RL 4 01
IC11
PWR AF
AMP MUTE
Q1
200kHz=>80dB
Q1202
BW=>30k
IC1601
Q1203
D1701
XTAL IF
BUFF
BPF AMP
24.2MHz
3rd/4th LO signal
from the PLL UNIT
SCOPE/TV UNIT
3 - 2
IC1305
IC1304
+
BUFF A/D
-
IC1401 IC1421
analog AF signals
D/A LPF
to the AFcircuits
PHONE
I
NTERNAL SP
REC
REMOTE
DET OUT
EXT. SP
LINE OUT
IC1602
LPF
AMP
200kHz
IC2201
IC2051
To the MAIN CPU2
(MAIN UNIT; IC604)
MAIN UNIT
Demodulated
SCOPE
A/D
DSP