RTS DV-3066, Руководство по обслуживанию, Страница: 5 / 30

DV3066
5-4. APC Circuit
The APC circuit always monitors the current flowing
through the RF power amplifier (Q505) and keeps a
constant current. The voltage drop at R589, R590 and
R591 is caused by the current flowing through the RF
power amplifier and this voltage is applied to the differential
amplifier U502(1/2). U502 (2/2) compares the output
voltage of U502 (1/2) with the reference voltage from U201.
The output of U502 (2/2) controls the VG of the RF power
amplifier, Drive amplifier and Pre-Drive amplifier to make
both voltages the same.
U203
EEPROM
U201
CPU
BATT1
R204
C200
U201
P72
MPU
R203
38
The change of power high/low is carried out by the
change of the reference voltage. (See Fig. 8)
6 Control Circuit
The microprocessor (U201) operates at a clock of
32.768KHz.The control circuit consists of a microprocessor
(U201) and its peripheral circuits. It controls the TX-RX unit.
U201 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.
6-1.
Memory Circuit
Memory circuit consists of the MPU (U201 and an
EEPROM (U203). An EEPROM has a capacity of 64k bits
that contains the transceiver control program for the MPU
and data such as transceiver channels and operating
features. (See Fig. 9)
Fig.9
6-2. Low battery warning
The battery voltage is monitored by the microprocessor
(U201). When the battery voltage falls below the voltage
set by the Low Battery Warning adjustment, the red LED
flashes to notify the operator that it is time to replace the
battery. If the battery voltage falls even more (approx.
6.0V), a beep sounds and transmission is stopped.
Low battery warning Battery condition
The red LED flashes
during transmission
The battery voltage is low but
the transceiver is still usable.
The red LED flashes
and a continuous beep
sounds while PTT
pressed.
The battery voltage is low and
the transceiver is not usable to
make calls.
Fig.10
7. Power Supply
There are four 5V power supplies for the microprocessor:
5M,5C,5R, and 5T. 5M for microprocessor 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.
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