Benison V7, Руководство по обслуживанию

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V7
5
3) UNLOCK DETECTOR
If a pulse signal appears at the LD pin of U301, an unlock condition occurs, and the DC
voltage obtained from D309, and C306 causes the voltage applied to the PLL-LD pin of
the microprocessor to go low. When the microprocessor detects this condition, the
transmitter is disabled, ignoring the push-totalk switch input signal. ( See Fig.3)
4. Transmitter
1)Microphone Amplifier
The signal from the microphone passes through U411.When encoding DTMF,it is turned
OFF for muting the microphone input signal by T414.The signal passes through the Audio
processor(U411) for the maximum deviation adjustment,and goes to the VCO modulation
input.
2)Drive and Final Amplifier
The signal from the T/R switch(D100) is amplified by the pre-drive(T101.T102) and drive
amplifier(T105) to 50mW.The output of the drive amplifier is amplified by the RF power
amplifier(T107) to 4.0W(1W when the power is low).the RF power amplifier consists of two
MOS FET stages.The output of the RF power amplifier consists of two MOS FET stages.
The output of the RF power amplifier is then passed through the harmonic filter (LPF) and
antenna switch (D101,D102)and applied to the antenna terminal.
5. 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 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.
6.Control Circuit
The control circuit consists of a microprocessor (U811) and its peripheral circuits.it
controls the TX-RX unit.U811 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.