TK-3207G
12
CIRCUIT DESCRIPTION /
电路说明
1. Frequency Configuration
The receiver utilizes double conversion. The first IF is 38.85
MHz and the second IF is 450 kHz. The first local oscillator
signal is supplied from the PLL circuit.
The PLL circuit in the transmitter generates the necessary
frequencies. Fig. 1 shows the frequencies.
Fig. 1 Frequency configuration /
图 1 频率构成
1) Front End (RF AMP)
The signal coming from the antenna passes through the
transmit/receive switching diode circuit, (D103,D104,D106
and D122) passes through a BPF (L229 and L228), and is
amplified by the RF amplifier (Q205).
The resulting signal passes through a BPF (L214,L212 and
L211) and goes to the mixer. These BPFs are adjusted by
variable capacitors (D203,D204,D205,D206 and D210). The
input voltage to the variable capacitor is regulated by
voltage output from the microprocessor (IC405).
2) First Mixer
The signal from the front end is mixed with the first local
oscillator signal generated in the PLL circuit by Q1 to
produce a first IF frequency of 38.85 MHz.
The resulting signal passes through the XF201 MCF to cut
the adjacent spurious and provide the opitimun
characteristics, such as adjacent frequency selectivity.
Fig. 2 Receiver section /
图 2 接收部
2. Receiver
The frequency configuration of the receiver is shown in Fig. 2.
SP
BPF
IC301
ANT
AQUA-L
CF201
TCXO
TUNE
TUNE
ANT SW
BPF
1st Local
MIXER
Q204
RF AMP
Q205
MCF
XF201
IC201
IF,MIX,DET
Q1
X3 multiply
IC302
AF PA
IF AMP
Q203
AF VOL
X1
12.8MHz
2nd Local
1 . 频率构成
本接收机使用二次变频。第一 IF 是 38.85 MHz,第二 IF 是
450 kHz。第一本地振荡信号由 PLL 电路提供。
PLL 电路产生需要的发射频率。
2 . 接收部
接收部的频率构成如图 2 所示。
1) 前端 (RF 放大器)
从天线接收的信号进入发送 / 接收转换开关二极管电路
(D103,D104,D106 和 D122),然后通过 BPF (L229 和 L228),
并且被 RF 放大器 (Q205) 放大。
此信号通过 BPF (L214,L212 和 L211) 然后进入混频。这些
BPF 被可变电容器 (D203,D204,D205,D206 和 D210) 调整。
输入可变电容器的电压被经微处理器 (IC405) 的电压输出调
整。
2) 第一混频器
前端的信号与 PLL 电路产生的第一本振信号在 Q1 混频 , 生成
38.85MHz 频率的第一中频信号。
生成的信号通过 XF201 MCF。
SP
PLL
VCO
IF SYSTEM
ANT
TCXO
X3 multiply
38.85MHz
MCF
AF
AMP
MIC
MIC
AMP
TX
AMP
RF
AMP
38.4MHz
CF
450kHz
TX/RX: 440 ~ 480MHz (C)
400 ~ 430MHz (C2)
370 ~ 390MHz (C5)
350 ~ 370MHz (C6)
TX: 440 ~ 480MHz (C)
400 ~ 430MHz (C2)
370 ~ 390MHz (C5)
350 ~ 370MHz (C6)
RX: 401.15 ~ 441.15MHz (C)
361.15 ~ 391.15MHz (C2)
331.15 ~ 351.15MHz (C5)
311.15 ~ 331.15MHz (C6)
12.8MHz
RF
AMP
ANT SW