Service Manual

PAGE 40 TECHNICAL DESCRIPTION
The -12.0V rail of the level translator is generated by U300B/C with D304 to D306
providing the required voltage multiplier effect. The high level negative signal is then split
into the four individual front-end negative DC values under software control by multiplexer
U902 and associated storage capacitors C904 to C907 before being applied to the
anodes of the front-end tuning varactors.
Figure 3.5 - VHF/UHF Receiver Block Diagram
9
0
0
0
_
1
6
A
n
t
e
n
n
a
S
w
i
t
c
h
D
3
,
D
4
&
D
5
A
n
t
e
n
n
a
F
i
l
t
e
r
L
1
0
,
L
1
1
&
L
1
2
9
0
M
H
z
L
.
O
.
Q
4
0
2
R
x
V
C
O
Q
6
0
0
R
x
V
C
O
S
w
i
t
c
h
Q
6
0
1
V
C
O
B
u
f
f
e
r
Q
6
0
4
/
6
0
5
S
y
n
t
h
e
s
i
s
e
r
B
u
f
f
e
r
Q
6
0
7
t
o
U
7
0
1
T
o
T
x
B
u
f
f
e
r
t
o
U
7
0
1
T
o
T
x
P
A
C
P
P
V
C
O
C
o
n
t
r
o
l
V
o
l
t
s
R
x
P
S
U
T
x
/
R
x
S
w
i
t
c
h
D
6
1
0
/
6
1
1
R
x
/
T
x
A
F
S
w
i
t
c
h
U
1
0
3
B
M
i
c
A
m
p
Q
8
1
2
B
a
n
d
p
a
s
s
F
i
l
t
e
r
R
F
A
m
p
Q
4
0
0
B
a
n
d
P
a
s
s
F
i
l
t
e
r
M
i
x
e
r
T
4
0
0
I
F
A
m
p
Q
4
0
1
S
p
e
a
k
e
r
A
m
p
U
5
S
p
k
r
S
w
i
t
c
h
Q
8
1
0
/
8
1
1
/
8
1
3
4
-
P
o
l
e
4
5
M
H
z
F
i
l
t
e
r
s
Z
4
0
1
/
4
0
2
A
F
A
m
p
U
8
0
3
A
u
x
A
F
O
/
P
A
m
p
U
8
0
3
I
Q
D
e
m
o
d
u
l
a
t
o
r
U
4
0
1
R
x
A
F
S
w
i
t
c
h
U
1
0
3
C
A
G
C
B
u
f
f
e
r
U
9
0
1
B
A
D
C
/
D
A
C
C
O
D
E
C
U
8
0
0
F
r
o
m
M
u
l
t
i
p
l
e
x
e
r
U
9
0
2
T
u
n
e
1
,
2
,
3
&
4
Q
I
A
F
C
/
R
e
f
O
S
C
/
M
O
D
A
u
d
i
o
I
n
F
r
o
m
M
i
c
A
u
d
i
o
o
r
O
p
t
i
o
n
A
u
d
i
o
F
r
o
m
M
u
l
t
i
p
l
e
x
e
r
U
9
0
2
F
r
o
m
F
P
G
A
/
D
S
P
A
U
D
O
u
t
S
P
K
R
O
N
S
P
K
R
O
U
T
1
S
P
K
R
O
U
T
2
T
X
M
O
D
1
T
o
T
X
V
C
O
S
Y
N
T
H
A
U
X
C
P