Kenwood TK-2212 Service Manual page 16

X3
Q408
H:OFF
L : ON
Fig. 8 Frequency shift circuit
2) Memory Circuit
Memory circuit consists of the CPU (IC405) and an EEPROM
(IC406). An EEPROM has a capacity of 64k bits that contains
the transceiver control program for the CPU and data such
as transceiver channels and operating features.
IC405
CPU
Fig. 9 Memory circuit
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)
(2)
R404
SB
Fig. 10 Low battery warning
CIRCUIT DESCRIPTION
11
XOUT
IC405
8
BSHIFT
Q407
H:OFF
L : ON
IC406
EEPROM
6.2[V]
5.8[V]
IC405
88
BATT
CPU
TK-2212/2217
7. Control System
LCD, Keys and channel selector circuit.
The signal from the keys and channel selector are directly
input to the microprocessor, as shown in fig. 11.
Channel selector
49
EN1
71
EN2
Fig. 11 Control system
27
PTT
PTT
SW
IC405
CPU
74
SIDE 1
SW1
75
SIDE 2
SW2
LCD
ASSY
15