Sailor RE2100, Technical Manual

Page: 103 / 186

5 CIRCUIT DESCRIPTION AND SCHEMATIC DIAGRAMS RE2100
AF FILTERS
To reduce white noise from the non-tuned IF amplifier, the AF signal from the detector is led through three
active filters in cascade.
A 5th order, 3 kHz lowpass filter is built-up around U04/3 and U04/4. A 3rd order, 70 Hz highpass filter
is built-up around U04/1, and a 3rd order, 350 Hz highpass filter is built-up around U02/2.
AM MODE
In AM mode only the LP filter and the 70 Hz HP filter is used. This is done by applying a logic high voltage
to the analog switch U07, pin 9.
SSB MODE
In SSB mode all filters are used by applying a logic low voltage to the analog switch U07, pin 9.
Filter selection is controlled by the microprocessor through the shift register U10, pin 2.
AF SWITCHES
From the output of the AF filter, the signal is fed through a number of analog switches, which are all
included in the three IC’s U7, U8, and U9. These switches are used to control the transfer of AF signals
between the RE2100 and the peripheral equipment, which as an example could be a telex modem, a
duplex receiver, and one or more remote control units. The interconnection between the individual
switches is shown in the block diagram below.
BLOCK DIAGRAM AF SWITCHES
DISPLAY MODULE (7)
RECEIVER MODULE (1)
PROCESSOR MODULE (5)
EXCITER MODULE (4)
POWER MODULE (8)
FRONT END MODULE (2)
Signal Meter
Volume Control & on/off
Loudsp. Buffer
Alarm/call tones
Shift
0 dBm AMP.
AF
Filters
Register 2 Register 1
Shift
Micro-
processor
AGC
Log. AMP Buffer AMP
2.IF 1.IF
Det. Mute
SSB
AM
Earpiece AMP.
DC supply for mic. AMP.
Dependent
on squelch
Indepent
on squelch
Detector
U8
U8
4
9
5
3
1
15
2
10
H1
G1
U7
U7
U7
15
2
1
4
5
3
14
13
12
9
11
10
F2
G2
C2
E2
E1
U8
12
13
14
12 13
14
11
A1
F1
560R
U9
15 1 2 3 4 5 6 7 15 1 2 3 4 5 6 7
A2 B2 C2 D2 E2 F2 G2 H2 A1 B1 C1 D1 E1 F1 G1 H1
4
5
3
9
B1
U9
15
U9
1
2
10
C1
RX Mute
RX/TX
Mic.
Aux.
Tune Tones
560R
56R
Exciter
Seriel data 0 dBm
Tune/alarm/call tones
AUX AF to TX
AF to AMP
Squelch Switch
11
Input from remote controle units to
earpiece/loudspeaker or input from
duplex receiver to earpiece/loudspeaker
Input from telex modem to
exciter or input from remote
controle units to exciter
Output from receiver to
loudspeaker amplifier
Output from receiver to
remote controle units
Output from microtelephone to
remote controle units
HANDSET
26582
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