Kirisun DR600 Service Manual

DR600 Service Manual
3. Circuit Description
3.1 RF Circuit
The RF part is composed of transmitter module, power amplifier module and receiver module.
3.1.1 Tx Circuit
Figure 3-1 Transmitter Circuit
X100
MODE1
SDATA
TXPLLCS
SCLK
TXLD
MODEIN
Q2002
IC100 SKY72310
IC306
U402
TOTXPA
MODE2
TXVCOSELECT
TXVCO1+TXVCO2
Q105
Q106
TXENABLE
Transmitter circuit includes three parts:
 Two Point Modulation Circuit
The RF center frequency calibration from the baseband and the low frequency part of 4FSK signal will
be processed with addition algorithm, then sent to the DAC to get MODE1 signal. The MODE1 directly
enters the reference clock X100, which is used for center frequency control and low frequency modulation.
The MODE2 signal, which passes the two-level low pass filter which is composed of IC301s for DAC
sampling interference filter, will be sent into VCO for high frequency part modulation.
 Transmitter Frequency Generation Unit Circuit
The transmitter PLL includes two VCOs,one PLL(IC100) IC SKY72310 and reference clock X100. The
transmitting frequencies of the two VCOs controlled by the TXVCOSELECT signal are 400~435MHz and
435~470MHz respectively.(VHF is 136~155MHz and 155~174MHz)
a. Working Principle of Voltage Controlled Oscillator
The Tx Module employs two VCOs which cover the band of 400~435MHz and 435~470MHz (VHF is
136~155MHz and 155~174MHz). The switch of VCO is controlled by the TXVCOSELECT signal. VCO
employs three point capacitance oscillation circuit. The VCO that covers the band of 400~435MHz (VHF is
136~155MHz) is composed of D106~D109、L119、Q106 and some other components, while the VCO
covers the band of 435~470MHz (VHF is 155~174MHz) is composed of D101~D104、L107、Q105 and
some other components.
b. Working Principle of Frequency Generation Unit
4

Kirisun DR600 Specifications

General

Brand	Kirisun
Model	DR600
Category	Repeater
Language	English