Section 4 Technical Description; General; The Transmitter/Receiver/Pll Section - Raymarine Apelco 5200 User Manual

4.1 GENERAL

The VHF5200 can be considered as consisting of two major sections. They are:
The Control Circuitry (consisting of the front panel controls, the LCD display, control
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CPU).
The Transmitter/Receiver/PLL
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4.2 THE CONTROL SECTION
The heart of the control section is the CPU, IC201, located on the main PCB.
The CPU controls all of the following items:
Controls the Squelch circuit by detecting a busy signal from the second IF circuit IC5.
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Generates a beep tone when a key is activated on the keyboard.
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Mutes the transmitter modulation circuit when receiving.
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Controls the output power of the transmitter High/Low.
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Controls the dividing ratio N of the PLL circuit.
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Switches On/Off the transmitter power.
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Mutes AF audio.
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Detects a weather alert signal (when in Monitor Mode).
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Controls the LCD display.
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4.3 THE TRANSMITTERIRECEIVERPLL
In reading through the following circuit descriptions, it may be helpful to refer to Figure 4-l Block
Diagram of the TX/RX/PLL
SECTION 4
TECHNICAL DESCRIPTION
circuits.
SECTION
circuits.
16