TK-3302
11
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Frequency Shift Circuit
The MCU (IC306) operates at a clock of 14.746 MHz. This
oscillator has a circuit that shifts the frequency by BEAT
SHIFT SW (Q305, Q306).
A beat sound may be able to be evaded from generation
if “Beat Shift” is set to ON when it is generated in the inter-
nal spurious transmission modulated sound of a transceiver.
X301
XOUT
XIN
BSHIFT
Q305
Q306
IC306
MCU
Hi: ON
Low: OFF
Fig. 8 Frequency shift circuit
■
Memory Circuit
Memory circuit consists of the MCU (IC306) and an EE-
PROM (IC305). An EEPROM has a capacity of 16k bits that
contains the transceiver control program for the MCU and
data such as transceiver channels and operating features.
MCU
EEPROM
IC306
IC305
Fig. 9 Memory circuit
■
Low Battery Warning
The battery voltage is checked using by the MCU. 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. Dur-
ing 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
Ni-MH Battery
Li-ion Battery
(1)
6.2V
6.2V
6.2V
(2)
5.9V
5.9V
5.9V
CIRCUIT DESCRIPTION
66
IC306
MCU
R301
SB
R305
Fig. 10 Low battery warning
7. Control System
Keys and channel selector circuit. The signal from the
keys and channel selector are directly input to the MCU, as
shown in Fig. 11.
EN1
62
55
56
57
Channel
selector
61
60
59
58
EN2
EN3
EN4
EN5
IC306
MCU
SIDE1
PTT
PTT
SW
SW1
SW2
SIDE2
Fig. 11 Control system