3. TECHNICAL
DESCRIPTION
10.1 General
The RAY53 can be considered as consisting of two major sections.
-. The control section(consisting of the front panel controls ,LCD display,and
CPU
-. The transmitter/Receiver/PLL section.
10.2 The Control Section
.
The heart of the control section is the CPU,which is IC201 located on the
CNTL PCB. The CPU controls all of the following items:
-. Controls the Squelch circuit by detecting a busy signal from the 2
nd
IF
circuit IC3 on the RF PCB.
-. Generates a beep tone when a key is activated on the keyboard.
-. Mutes the transmitter modulation circuit when receiving.
-. Controls the output power of the transmitter High/Low.
-. Controls the dividing ratio N of the PLL circuit.
-. Switches On/Off the transmitter power.
-. Mutes AF audio.
-. Detects a weather alert signal(when in Monitor Mode)
-. Controls the LCD display.
3. 3 The transmitter/Receiver/PLL Sections
In reading through the following circuit descriptions, it may be helpful to
refer to Block Diagram of the TX/RX/PLL circuits.
10.3 1. PLL(Phase Lock Loop) Circuit
PLL circuit of this radio is PLL IC(IC2) and is composed of VCO circuit which is for
Transmitter and for Receiver independently. PLL IC(IC2)
generates
the setting frequency
based on the control data of CPU(IC201).
The reference oscillating frequency of the PLL circuit is 21.25MHz and is consisting of
crystal resonator X1 and IC2. This oscillating frequency 21.25MHz is divided into 1/850 to
