TK-2360
12
RF
AMP
Audio
processor
VCO
PLL
MCU
IC809
PLLLE,PLLCLK,PLLDAT
IC1
PLLLD
17
10
21
7
BUFF
SW
LPF
To mixer
VC
Q9
BUFF
Q8
TCXO
X1
IC812
SW
To
RF AMP
TX
(TX: High)
D18
D17
Q2
CV
Fig. 6 PLL block diagram
6. Control Circuit
The control consists of the MCU (IC809) and its peripher-
al circuits. It controls the TX-RX unit. IC809 mainly performs
the following;
1) Switching between transmission and reception by PTT
signal input.
2) Reading channel information, frequency, and program
data from the memory circuit.
3) Sending frequency program data to the PLL.
4) Controlling squelch on/off via the DC voltage from the
squelch circuit.
5) Controlling the audio mute circuit via the decode data in-
put.
6) Transmitting tone and encode data.
6-1. Frequency Shift Circuit
The MCU (IC809) operates at a clock frequency of
12.0MHz. This oscillator has a circuit that shifts the frequen-
cy via Beat shift switch (Q806, Q807).
A beat sound may be able to be evaded form generation
if “Beat Shift“ is set to ON when it is generated in the in-
ternal spurious transmission modulated sound of the trans-
ceiver.
X802
11
9
13
XOUT
XIN
BSHIFT
Q806
Q807
IC809
MCU
H: OFF
L: ON
C846
C854
Fig. 7 Frequency shift circuit
6-2. Memory Circuit
The Memory circuit consists of the MCU (IC809) and EE-
PROM (IC810). The EEPROM has a capacity of 64k bits and
stores the channel information, the last channel data, the
scan on status, and other parameters.
■
EEPROM
Note:
The EEPROM stores tuning data (Deviation, Squelch,
etc.).
Realign the transceiver after replacing the EEPROM.
MCU
EEPROM
IC809
IC810
Fig. 8 Memory circuit
6-3. Low Battery Warning
The battery voltage is monitored by the MCU (IC809 pin
86: BATT). When the battery voltage falls below the volt-
age set by the Low Battery Warning adjustment, the red
LED blinks, notifying the operator that it is time to replace
the battery (when the always option (default setting) under
the Battery Warning function in the FPU is selected). If the
battery voltage falls bellow 5.9V, the transceiver does not
transmit and the warning tone beeps while the PTT switch
is pressed.
Low battery warning
Battery status
The red LED blinks during trans-
mission.
The battery voltage is low but
the transceiver is still usable.
The red LED blinks and the
warning tone beeps while the
PTT switch is pressed.
The battery voltage is lowand
the transceiver cannotbe used
to make calls.
86
IC809
MCU
BATT
R824
SB
R829
Fig. 9 Low battery warning
6-4. Battery Type Detection
The transceiver automatically detects the battery type,
measuring the resistance between the S-terminal and +ter-
minal on the battery pack and changes the supplied voltage
to the S-terminal as below. The MCU then detects the bat-
tery type.
Resistor value
Battery type
Input voltage of S-terminal
1.8M
Ω
Li-ion
0.3~1.3V
560k
Ω
Ni-Cd
1.3~2.6V
220k
Ω
Ni-MH
2.6~5.0V
OPEN
Battery case
0~0.3V
CIRCUIT DESCRIPTION
