Kenwood TK-2160 - Manual (Page 10)

TK-2160
10
2) Memory Circuit
Memory circuit consists of the CPU (IC805) and an EEPROM
(IC804). 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.
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.
(2) The red LED blinks when the battery voltage falls below
the voltage (2) 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.
(3) The transceiver immediately stops transmission when
the battery voltage falls below the voltage (3) shown in
the table. A message tone beeps while the PTT switch
is released.
CIRCUIT DESCRIPTION
6. Control Circuit
The control circuit consists of a microprocessor (IC805) and
its peripheral circuits. It controls the TX-RX unit. IC805 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 (IC805) operates at a clock of
7.3728MHz. This oscillator has a circuit that shifts the
frequency by BEAT SHIFT SW (Q810).
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.
20 of the CPU. The signal passes through a low pass CR
filter, mixes with the audio signal, and goes to the VCO
modulation input. TX deviation is adjusted by the CPU.
(2) DTMF/2 TONE
High-speed data is output from pin 2 of the CPU. The signal
passes through a low-pass CR filter, and provides a TX and
SP out tone, and is then applied to the audio processor
(IC601). The signal is mixed with the audio signal and goes
to the VCO.
TX deviation is adjusted by the CPU.
(3) MSK (Fleet Sync)
The MSK input signal from the IF IC is amplified by IC602
(1/2) and goes to pin 31 of IC 601. The signal is demodulated
by MSK demodulator in IC 601. The demodulated data goes
to the CPU for processing.
5. Power Supply
There are 3.5V power supply for PLL circuit and five 5V
power supplies for the microprocessor: 5M,5MS,5C,5R, and
5T. 5M is always output while the power is on. 5M is always
output, but turns off when the power is turned off to prevent
malfunction of the microprocessor.
5C is a common 5V and is output when SAVE is not set to
OFF.
5R is 5V for reception and output during reception.
5T is 5V for transmission and output during transmission.
X801 C834
XOUT
IC805
Q810
Hi: OFF
LOW: ON BSHIFT
Fig. 10 Frequency shift circuit
Fig. 11 Memory circuit
IC805
CPU
IC804
EEPROM
Battery Case Li-ion Battery Ni-Cd Battery Ni-MH Battery
(1) 6.2[V] 6.5[V] 6.2[V] 6.2[V]
(2) 7.6[V] 7.1[V] 6.8[V] 7.0[V]
(3) 5.9[V] 6.2[V] 5.9[V] 5.9[V]
SB R833
R834
88
IC805
CPU
Fig. 12 Low battery warning