Kirisun PT8000, Руководство по обслуживанию

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PT8000 Service Manual
3
5) Volume Knob
Rotate to adjust the volume of the radio.
6) MIC Jack/Programming Interface
7) P1Button (Programmable Button)
8) P2 Button (Programmable Button)
9) P3 Button (Programmable Button)
10) PTT Button (on the hand microphone)
Press and hold the PTT button, then speak into the microphone,
your voice can be transmitted to the recipient. Release PTT to
receive.
3.2 LCD Display Screen
Display Description
SCAN
Indicator
Scan function indication: ON when scan function is enabled.
LOW
Indicator
Tx power level indication: ON when the radio is in low power.
Indicates the current channel number when in normal use, ranging
from 1~8.
Indicates the current squelch level when Squelch Level Selection
function is enabled, ranging from 0~9.
Displays “b” when Public Address function is enabled.
Displays “-” when channel information has not been programmed.
Displays “u” when the radio is stunned.
Displays “h” when the radio is killed.
Displays “P” when the radio is in the PC Programming Mode.
Displays “t” when the radio is in the PC Tuning Mode.
Displays “C” when the radio is in the Wired Clone Mode.
3.3 Rear Panel
① ② ③
1) Antenna Connector
2) Power Terminal
3) External Speaker Jack
Chapter 4 Circuit Description
4.1 Frequency Configuration
ANT
ANT SW RF AMP
MCF
49.95MHz
IF SYSTEM
CF1
450KHz H
CF2
450KHz F
X3 multiply
AF AMP
TCXO
16.8MHz
MIC AMP PLL VCO TX AMP PA AMP
RX
TX
Figure 4.1 Frequency Configuration
The receiver adopts double mixing. The first IF is 49.95MHz
and the second IF is 450kHz.
The first local oscillator signal of the receiver is generated by
the frequency synthesizer and the second local oscillator signal is
generated by the frequency tripler X1.
The transmitter signal is produced by the frequency
synthesizer.
The reference frequency of the frequency synthesizer is
provided by TCXO.
4.2 Principle of Receiver
（
RX
）
Figure 4.2 Principle of Receiver
Front end
The signal coming from the antenna passes through the
RX/TX switch (D3 and D11), and passes through a BPF consists
of two LCs to remove unwanted out-of-band signals, and then is
routed to the low noise amplifier (LNA) consists of Q18 and its
peripheral components where it is amplified.
Output signal from the LNA passes through a BPF consists of
three LCs to further remove unwanted out-of-band signal, and
then goes to the first mixer (Q19).
AGC circuit
AGC circuit, which consists of Q16 and its peripheral circuit,
will work to reduce the gain of Q18 only when the input signal is
too large.
First mixer
The Rx signal from LNA is mixed with the first local
oscillator signal from the frequency synthesizer to produce the
first IF signal (49.95MHz).
IF circuit
MCF
49.95MHz
IF SYSTEM
CF1
450KHz H
CF2
450KHz F
X3 multiply
AF AMP
TCXO
16.8MHz
NJM2902
BPF
RF AMP
BPF
ANT SW
ANT
IC11
MCU 1st Local OSC
D3 D11
Q18 Q19
IC4
IC9
IC9 TDA1519C