TK-3160
10
CIRCUIT DESCRIPTION /
电路说明
1. Frequency Configuration
The receiver utilizes double conversion. The first IF is 49.95
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.
1) Front End (RF AMP)
The signal coming from the antenna passes through the
transmit/receive switching diode circuit, (D204,D206,D208
and D212) passes through a BPF (L413 and L414), and is
amplified by the RF amplifier (Q404).
The resulting signal passes through a BPF (L409,L408 and
L407),and goes to the mixer. These BPFs are adjusted by
variable capacitors (D402,D403,D404,D405 and D406). The
input voltage to the variable capacitor is regulated by
voltage output from the microprocessor (IC805).
2) First Mixer
The signal from the front end is mixed with the first local
oscillator signal generated in the PLL circuit by Q403 to
produce a first IF frequency of 49.95 MHz.
The resulting signal passes through the XF401 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
IC602
AF Amp
IC601
IC605
AF PA
IC401
IF,MIX,DET
ANT
AQUA
CF401
TCXO
TUNE
Q4
X3 multiply
TUNE
ANT SW
BPF
MCF
1st Local
RF AMP
Q404
MIXER
Q403
XF401
IF AMP
Q402
AF VOL
X1
16.8MHz
2nd Local
SP
PLL
VCO
IF SYSTEM
ANT
TCXO
X3 multiply
49.95MHz
MCF
AF
AMP
MIC
MIC
AMP
TX
AMP
RF
AMP
50.4MHz
CF
450kHz
16.8MHz
RF
AMP
ANT SW
TX/RX: 440 ~ 480MHz (C)
400 ~ 430MHz (C2)
TX: 440 ~ 480MHz (C)
400 ~ 430MHz (C2)
RX: 390.05~430.05MHz (C)
350.05~380.05MHz (C2)
1 . 频率构成
本接收机使用二次变频。第一 IF 是 49.95 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
(D204,D206,D208 和 D212),然后通过 BPF (L413 和 L414),
并且被 RF 放大器 (Q404) 放大。
此信号通过 BPF (L409,L408 和 L407) 然后进入混频。这些
BPF 被可变电容器 (D402,D403,D404,D405 和 D406) 调整。
输入可变电容器的电压被经微处理器 (IC805) 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 Q403 混频 , 生
成 49.95MHz 频率的第一中频信号。
生成的信号通过 XF401 MCF。
Fig. 1 Frequency configuration /
图 1 频率构成