Kenwood TK-3360 Service Manual page 12

TK-3360
Q8
TX VCO BUFF
(TX: High)
CV
LPF
IC1
21
PLL
7
PLLLD
MCU
PLLLE,PLLCLK,PLLDAT
IC809
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.
BSHIFT
9
C846
H: OFF
L: ON
Q806
Fig. 7 Frequency shift circuit
12
CIRCUIT DESCRIPTION
Q9 D18
BUFF SW
Q2 D17
RF
SW
AMP
To mixer
17
VC
Audio
TCXO
processor
10
X1 IC812
IC809
MCU
XOUT XIN
11 13
X802
C854
Q807
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
To
RF AMP
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.
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
The red LED blinks during trans-
mission.
The red LED blinks and the
warning tone beeps while the
PTT switch is pressed.
SB
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
1.8MΩ
560kΩ
220kΩ
OPEN
IC809 IC810
MCU EEPROM
Fig. 8 Memory circuit
Battery status
The battery voltage is low but
the transceiver is still usable.
The battery voltage is lowand
the transceiver cannotbe used
to make calls.
R824
86
BATT
IC809
MCU
Battery type Input voltage of S-terminal
Li-ion 0.3~1.3V
Ni-Cd 1.3~2.6V
Ni-MH 2.6~5.0V
Battery case 0~0.3V