Circuit Description - Kenwood TK-2212L Service Manual

TK-2212L
6. Firmware Version Information
Turn the transceiver ON with the [Side1] and [Side2] keys
held down. Then, the version is displayed during holding the
[Side1] and [Side2] keys.

CIRCUIT DESCRIPTION

1. Control Circuit
The control circuit consists of a microprocessor (IC405) and
its peripheral circuits. It controls the TX-RX unit and transfers
data to the Display unit. IC405 mainly performs the following:
(1) Switching between transmission and reception by the
PTT signal input.
(2) Reading system, group, frequency, and program data
from the memory circuit.
(3) Sending frequency program data to the PLL.
(4) Controlling squelch on/off by the DC voltage from the
squelch circuit.
(5) Controlling the audio mute circuit by the decode data
input.
(6) Transmitting tone and encode data.
1) Frequency Shift Circuit
The microprocessor (IC405) operates at a clock of
7.3728MHz. This oscillator has a circuit that shifts the
frequency by BEAT SHIFT SW (Q407, Q408).
A beat sound may be able to be evaded from generation if
"Beat Shift" is set to ON when it is generated in the internal
spurious transmission modulated sound of a transceiver.
X3
Q408
H:OFF
L : ON
Fig. 1 Frequency shift circuit
2) Memory Circuit
Memory circuit consists of the CPU (IC405) and an EEPROM
(IC406). An EEPROM has a capacity of 128k bits that
contains the transceiver control program for the CPU and
data such as transceiver channels and operating features.
IC405
CPU
Fig. 2 Memory circuit
8
REALIGNMENT / CIRCUIT DESCRIPTION
11
XOUT
IC405
8
BSHIFT
Q407
H:OFF
L : ON
IC406
EEPROM
3) Low Battery Warning
The battery voltage is checked by the microprocessor.
The transceiver generates a warning tone when the battery
voltage falls below the warning voltage (2) shown in the
table.
(1) The red LED blinks when the battery voltage falls below
the voltage (1) shown in the table during transmission.
Transmission is still allowed.
Note:
The transceiver checks the battery voltage during reception
even when, in the FPU, the Battery Warning status function
is set to "While Transmitting" (default setting).
However, the LED does not blink during reception. The red
LED blinks during transmission. The transceiver is still
usable.
(2) The transceiver immediately stops transmission when
the battery voltage falls below the voltage (2) shown in
the table. A warning tone sounds while the PTT switch
is pressed.
Ni-MH Battery
(1) 6.2V
(2) 5.8V
R404
SB
Fig. 3 Low battery warning
Li-ion Battery
6.2V
5.8V
IC405
88
BATT
CPU