Sailor RE2100 Technical Manual page 103

5 CIRCUIT DESCRIPTION AND SCHEMATIC DIAGRAMS
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)
Volume Control & on/off
Loudsp. Buffer
U8
U8
3
4
5 15
9
H1 0 dBm AMP.
G1
12 13
11
U9
A1
14
15 1 2 3 4 5 6 7
A2 B2 C2 D2 E2 F2 G2 H2
Shift
Register 2
PROCESSOR MODULE (5)
Output from microtelephone to
remote controle units
Input from telex modem to
exciter or input from remote
controle units to exciter
Output from receiver to
remote controle units
Input from remote controle units to
earpiece/loudspeaker or input from
duplex receiver to earpiece/loudspeaker
Output from receiver to
loudspeaker amplifier
26582
9324
Signal Meter
Buffer AMP
Dependent
on squelch
Indepent
on squelch
2
1
Squelch Switch
10
U7
2
15
1 U7
U7
5 SSB
10 4
13
3 AM
F2 14
12
9
11
C2
G2
U8
12
14
13
11
F1
15 1 2 3 4 5 6 7
A1 B1 C1 D1 E1 F1 G1 H1
Shift
Register 1
Micro- Tune/alarm/call tones
processor
AUX AF to TX
RECEIVER MODULE (1)
Log. AMP
E1
AGC
Detector
Det. Mute
AF
2.IF
Filters
Earpiece AMP.
E2
DC supply for mic. AMP.
U9
5
4
3
9
B1
U9
1
15
2
10
C1
EXCITER MODULE (4)
Mic.
Tune Tones
Exciter
Aux.
560R
FRONT END MODULE (2)
RX Mute
1.IF
RX/TX
POWER MODULE (8)
PAGE 5-3
RE2100
HANDSET