Kenwood TK-80, Руководство по обслуживанию

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TK-80
104
Circuit Description
The selective call unit consists of the DTMF decoder sec-
tion and the FSK decoder section circuits.
1. DTMF decoder
The DTMF tone input from the LCD assembly microphone
input connector is input to IC3 via the TX-RX unit. When an
effective tone is detected, the STD terminal becomes “H”
and an enable TOE is output from the control unit’s CPU.
This in turn causes DTMF decode data to be output from IC3
and Q1 to Q4. The control unit’s CPU reads in this DTMF
decode data, converts it to FSK data and transmits.
2. FSK decoder
The AF signal detected at the TX-RX unit is input to pin 2 of
IC1. If it is an effective tone, the tone detect signal is output
through buffer IC2 and FSL is sent to the control CPU. FSK
decode data is sent from pin 7 of IC1 through buffer IC2 as
the FSD to the control unit’s internal CPU. The CPU detects
conformity with code set for that unit and changes the mode
clears AF muting, etc.
The IC1 internal VCO central frequency (fo) is determined
by C5, R9 and VR1 and adjusted to 2210Hz. The tracking
bandwidth (
∆
f) is determined by R6, R9, and VR1.
KPE-1 (Selective Call Kit)
External View
Components Description
SELECTIVE CALL UNIT (X52-3300-20)
Ref. No. Use / Function Operation / Condition
IC1 FSK demodulator
IC2 Buffer
IC3 DTMF decoder
D4 LED Lights when “MARK” signal input
D5 LED Lights when “SPACE” signal input
D6 LED Lights when “FSK” signal input
Terminal Function
CN No. Pin No. Pin Name Function
CN1 1 AF Audio
2 AFG Audio GND
3 MIC MIC signal input
4 MICG MIC GND
CN2 1 DGND Digital GND
2 TOE DTMF decoder control
3 Q1 DTMF decode data
4 Q2 DTMF decode data
5 Q3 DTMF decode data
6 Q4 DTMF decode data
7 STD Single tone detector
8 DGND Digital GND
9 5A 5V
10 FSD Selective call data
11 FSL Selective call signal detector
12 DGND Digital GND
1. Frequency 1) S1 changes to TEST. f. counter Selective TP1 Selective VR1 2210Hz
±
2Hz
adjustment call call
Item Condition
Measurement Adjustment
Specifications/
Remarks
Test-
equipment
Unit Terminal Parts Unit Method
Adjustment