Selective Call Kit) - Kenwood TK-80 Service Manual

TK-80
External View
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.
Adjustment
Item
1. Frequency 1) S1 changes to TEST.
adjustment
104
KPE-1 (Selective Call Kit)
Measurement
Condition
Test-
equipment
f. counter Selective TP1
Components Description
SELECTIVE CALL UNIT (X52-3300-20)
Ref. No. Use / Function
IC1 FSK demodulator
IC2 Buffer
IC3 DTMF decoder
D4 LED
D5 LED
D6 LED
Terminal Function
CN No. Pin No. Pin Name
CN1 1 AF
2 AFG
3 MIC
4 MICG
CN2 1 DGND
2 TOE
3 Q1
4 Q2
5 Q3
6 Q4
7 STD
8 DGND
9 5A
10 FSD
11 FSL
12 DGND
Adjustment
Unit Terminal Unit Parts
Selective VR1
call call
Operation / Condition
Lights when "MARK" signal input
Lights when "SPACE" signal input
Lights when "FSK" signal input
Function
Audio
Audio GND
MIC signal input
MIC GND
Digital GND
DTMF decoder control
DTMF decode data
DTMF decode data
DTMF decode data
DTMF decode data
Single tone detector
Digital GND
5V
Selective call data
Selective call signal detector
Digital GND
Specifications/
Method
Remarks
2210Hz ± 2Hz