Kenwood TK-2202 Service Manual page 11

X2
Q407
Q408
Hi: OFF
LOW: 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 using by the microprocessor.
The transceiver generates a warning tone when it falls below
the warning voltage shown in the table.
(1) The red LED blinks when the battery voltage falls below
the voltage (1) shown in the table during transmission.
Note:
The transceiver checks the battery voltage during reception
even when, in the FPU, the Battery Warning status function
is set to "On TX" (default setting).
However, the LED does not blink during reception. During
transmission, the LED blinks to generate the warning tone
of a low battery voltage.
(2) The transceiver immediately stops transmission when
the battery voltage falls below the voltage (2) shown in
the table. A message tone beeps while the PTT switch
is released.
Ni-Cd Battery
(1) 6.2[V]
(2) 5.9[V]
R404
SB
Fig. 10 Low battery warning
CIRCUIT DESCRIPTION
XOUT
IC405
BSHIFT
IC406
EEPROM
Ni-MH Battery
6.2[V]
5.9[V]
IC405
88
CPU
TK-2202/2206
7. Control System
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
50
EN1
49
EN2
48
EN3
47
EN4
46
EN5
Fig. 11 Control system
27
PTT
PTT
SW
IC405
CPU
74
SIDE 1
SW1
75
SIDE 2
SW2
11