Kenwood TK-80 Service Manual page 20

5-9. Beep
The beep signal is generated using the timer in the micro-
computer. A dot lasts about 40ms, a dash about 120ms. The
oscillation frequency is about 1.4kHz.
5-10. PLL and DDS control circuit
The TK-80 has one PLL and two DDSs. The main micro-
computer outputs frequency data to the PLL and DDSs seri-
ally according to the display frequency.
IC7
I/O port
11
VEN1
10
FEN1
9
FEN2
8
FEN3
34
UCK
35
UDA
IC5
CPU
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CIRCUIT DESCRIPTION
1
VI1 VI8
VO1
VO8
VO2 VO7
VI2 VI7
5V VDD GND
VEN1 RESET
UCK VDA
UDA DO
VI3 VI6
VO3 VO6
VO4 VO5
12
VI4 VI5
IC13
D/A converter
CN4 CN14
17
FEN3 FEN3
18
FEN2 FEN2
19
VEN1 VEN1
20
UCK UCK
UDA 21 UDA
FEN1 22 FEN1
CONTROL UNIT TX-RX UNIT
Fig. 14 TX-RX unit control signal
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5-11. TX-RX unit control signal circuit
The microcomputer sends the mode signal, IF filter select
signal, power signal, band-pass filter signal, MIC gain, and
CAR level data to the TX-RX unit. It receives meter signals
and standby switch signals from the TX-RX unit, displays data
on the meters, and performs the transmit operation. The
output signal from the microcomputer goes to the serial-to-
parallel converter IC16, IC15 and IC10, D/A converter IC13
(Fig. 14).
MIC OUT
AFVR
Power control
24
5V
TX GAIN
CAR level
13
5V
SSB, CW mode signal
AM mode signal
IC16
Serial/Parallel
1 20
Vss Vdd 5V
NC OE
UDA
DATA SO
UCK
CLK Q11
FEN3
LCK Q10
AM MMU2
Q0 Q9 MIC mute 2
MMU1
MIC mute 1
Q1 Q8
SCB ABK
AF blanking
Q2 Q7
VCAS
VCA singal
Q3 Q6
VOXS PMU
Q4 Q5 Power OFF AF blanking
10 11
VOX signal
IC15
Serial/Parallel
1 20
Vss Vdd 5V
NC OE
UDA
DATA SO
UCK
CLK Q11
FEN2
LCK Q10
IF1
Q0 Q9
IF2 AIP
AIP signal
Q1 Q8
IF3 PL
Q2 Q7 Power meter gain signal
IF4 RBK
Q3 Q6 RF balnking signal
AGS NBS
Q4 Q5 NB signal
10 11
AGS select
IF filter 0.5kHz
IF filter 2.2kHz
IF filter 2.7kHz
IF filter 6.0kHz
IC10
RX BPF data
Serial/Parallel
9 8
B8 B1
B7 B2
B6 B3
B5 B4
UDA NC
UCK FEN1
RES EN
5V GND
16 1
TK-80
19