HYT RPU416A, Руководство пользователя

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RPU416A Circuit Description
switching circuit before it is passed to the antenna terminal. The transmit/receive switching circuit is
comprised of D101, D102 and D103. D102 and D103 turned on (conductive ) in transmit mode and off
(isolated) in receive mode.
5) APC
The automatic power control (APC) circuit stabilizes the transmitter output power at a predetermined
level by sensing the drain current of the final amplifier Field Effect Transistor (FET). The voltage obtained
from the above drain current with a reference voltage which is set using the microprocessor. An APC
voltage proportional to the difference between the sensed voltage and the reference voltage appears at
the output of IC100 (1/2). This output voltage controls the gate of the FET power amplifier, which keeps
the transmitter output power can be varied by the microprocessor which in turn changes the reference
voltage and hence , the output power.
6) Terminal protection circuit
When the thermistor (TH102) reaches about 80
"
, the protection circuit turns on Q110 to protect
transmitting final amplifier (Q107).
5. Power supply
A 5V reference power supply [5M] for the control circuit is derived from an internal battery. This
reference is used to provide a 5V supply in transmit mode [5T] ,a 5V supply in receive mode [5R] , and a
5V, supply common in both modes [5C] based on the control signal sent
from the microprocessor.
6. Control system
The IC403 CPU operates at 7.37MHZ. This oscillator has a circuit that shifts the frequency according to
the EEPROM data.