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Circuit Descriptions, Abbreviation List, and IC Data Sheets
FM Detector, Stereo Decoder, Amplifier
RECEIVER/BACKEND
2708
3712
47n
10K
2707
10u 16V
3713
2K2
3741
LA1836M
3742
100R
4k7
MUTE
LEVEL
F708
F708
I.F. RADIO
The IF signal is demodulated in the 7710 (LA1836M), the IF
Radio IC. This IC has a coil FM detector that is aligned (for
alignment instructions see chapter "Electrical Alignments").
The stereo decoder is integrated and needs no adjustment.
The demodulated signal is filtered with 1730/1740. These filters
are pre-aligned and are reducing the pilot- and sub carrier
frequency. This is necessary to prevent wrong operation of the
expander circuit.
F747
F747
P20
BF545A
7705
7706
BC857B
P21
R
Figure 9-27 Sliding stereo circuit
There is a sliding stereo circuit for reducing the stereo noise at
low signal field strengths. Transistor 7705 is short-circuiting the
Audio Left and Audio Right signals at low field strengths. The
crossover level must be aligned (for alignment instructions see
chapter "Electrical Alignments"). There is also a "mute level"
alignment, which is set at 10 V RF input level. At this signal
level, the wireless audio link is muted.
2709
1n5
2710
470p
7710
AM
AM
DECODER
OSC
RF-AMP
AGC
ANTI BIRDIE
ALC
BUFF
AM
AM
AM
IF
DET
MIX
S-METER
AM
FM
IF
BUFF
COMP
TUNING
S-CURVE
DRIVE
AM
LEVEL
DET
FM
FM
FM IF
DET
REG
GND
VCC
Figure 9-26 IF demodulator circuit
3714
22K
6711
BAS316
S
CL36532008_084.eps
290403
1730
6
3
3745
O
I
4
1
NC
GND
5
2
FXM2
16V
10u
2720
16V 10u
2721
STEREO
SWITCH
STEREO
DRIVE
MUTE
TRIG
VCO
FF
FF
FF
AM
FM
PHASE
PILOT
SW
DET
DET
+8V
1u
+8V
2725
+8V
EM6E AB
9.
1740
6
3
O
I
4
1
NC
GND
5
2
FXM2
F715
F714
F715
F714
CL36532008_083.eps
EN 163
3746
290403
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