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13-8 IF
1) SAW FILTER
It passes only needed band of the signal that is converted to IF frequency and decrease the others band to
minimize the effect of adjacent channel.
2) RF AGC Control
It used adjusting to determine RF AGC working point in tuner.
3) VCO Tank
When VCO tank detects PLL, it makes the signal which sets a standard.
4) AFT (Auto Frequency Tuning)
AFT automatically controls the oscillator frequency in the tuner, so that it retains a constant level.
It is a quadrature detection type. The carrier, which is detected from video det is directly input to AFT.
The 90 degree delayed phase signal is input at the same time to AFT and, the results come out.
5) IF AMP
IF signal , which is selected in Saw filter, is amplified in IF amp frequency enough to be detected. The IF amp
has parallel inputs & outputs structure.
d
4.5 MHz
Tunlng
b
RF AGC Control
a
SAM Filter
From
(IF Amp)
Tuner Section
To Tuner Section
RF AGC
AFT Tank
To Tuner Section
Samsung Electronics
1
FM Det
2
Video Det
Video Amp
4
5
N.S.C
6
APC
Det
APC Tine
Const SW
Pra
Mix
Amp
Lock Det
10
11
RF AGC Amp
IF AGC
AFT
12
Fig. 13-11
Lim Amp
24
AGC
21
EQ.Amp
19
B/W
17
VCD
16
15
14
3
4
+B
AUDIO OUT
Circuit Operating Descriptions
SIF filter
4.5MHz
SIF Trap
c
VCD Tank
5
6
AFT OUT
VIDEO OUT
13-15
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