Q1051/Q1052/
Q1053/Q1054
LO
AMP
Q1471
LO
AMP
Q2471
Q2051/2052
U1Lo
BPF
XTAL
71.25 MHz
FI731
LO
AMP
Q601
90deg
IC501
IF
AM P
IC521
IF
AM P
Q701/Q702
D651
IF
AM P
IC521
90deg
BUFF
IC611
BUFF
IC611
BUFF
Q551
D655
Σ
IC501
BUFF
IC611
IF
AMP
Q711
BUFF
Q541
UR2Lo
IF
AMP
IC121
VR2Lo
D255
BUFF
IC211
BUFF
IC211
IF
AM P
Q301/302
IF
AM P
Q311
BUFF
IC211
D251
BUFF
Q141
90deg
LO
AMP
Q201
BUFF
Q151
IF
AMP
IC121
BPF
XTAL
10.85 MHz
FI331
URIF
HPF
LPF
HPF
ATT
HPF
HPF
LPF
90deg
IC101
Σ
IC101
VRI F
V1Lo
IF
AMP
Q1021
IF
AMP
Q2021
LPF
BPF
LO
AMP
IC2582
BPF
71.214 MHz
10.814 MHz
125.15~
163.15 MHz
From the VHF RF circuits
From the UHF RF circuits
from PLL UNIT
To MAIN UNIT
from PLL UNIT
from PLL UNIT
To MAIN UNIT
from PLL UNIT
3 - 3
VHF 1ST RX IF CIRCUITS (RF-B UNIT)
The RX signal from the RF circuits is applied to the 1st RX IF
mixer (Q1051–Q1054) to be mixed with the 1st RX LO signal
(125.15–163.15 MHz) from the PLL UNIT, resulting in the
10.85 MHz 1st RX IF signal.
The 1st RX IF signal is passed through the 1st IF filter
(FI331), amplifi ed by two 1st RX OF AMPs (Q301, Q302 and
Q311), and then applied to the 2nd RX IF circuits.
UHF 1ST RX IF CIRCUITS (RF-B UNIT)
The RX signal from the RF circuits is applied to the 1st RX IF
mixer (Q2051, Q2052) to be mixed with the 1st RX LO signal
(348.75–408.75 MHz) from the PLL UNIT, resulting in the
71.25 MHz 1st RX IF signal.
The 1st RX IF signal is amplified by the 1st RX IF AMP
(Q2021), passed through the 1st IF fi lter (FI731), and then
amplifi ed by two 1st RX IF AMPs (Q701, Q702 and Q711).
The amplifi ed 1st RX IF signal is applied to the 2nd RX IF
circuits.
VHF 2ND RX IF CIRCUITS (RF-B UNIT)
The 1st RX IF signal from the 1st RX IF circuits is divided
into two paths, and then each signal is applied to the 2nd
RX IF mixers (the image reduction mixers; D251/D255) to be
mixed with the 2nd RX LO signal (10.814 MHz) from the PLL
UNIT, resulting in the 36 kHz 2nd RX IF signal.
The image reduction mixer removes image frequency
components by using two LO signals which are 90 degrees
phase-shifted from each other.
The 2nd RX IF signals are independently amplified by the
buffers (Q151/Q141) and IF AMPs (IC121).
These amplifi ed 2nd RX IF signals are 90 degrees phase-
shifted and combined by the combiner (IC101), and then
applied to the MAIN UNIT.
UHF 2ND RX IF CIRCUITS (RF-B UNIT)
The 1st RX IF signal from the 1st RX IF circuits is divided
into two paths, and then each signal is applied to the 2nd
RX IF mixers (the image reduction mixers; D651/D655) to be
mixed with the 2nd RX LO signal (71.214 MHz) from the PLL
UNIT, resulting in the 36 kHz 2nd RX IF signal.
The image reduction mixer removes image frequency
components by using two LO signals which are 90 degrees
phase-shifted from each other.
The 2nd RX IF signals are independently amplified by the
buffers (Q551/Q541) and IF AMPs (IC521).
These amplifi ed 2nd RX IF signals are 90 degrees phase-
shifted and combined by the combiner (IC501), and then
applied to the MAIN UNIT.
• VHF/UHF 1ST RX IF AND 2ND IF CIRCUITS