NXR-810
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3-5. High temperature detector circuit
To prevent thermal destruction of amplifi er Q3 and fi nal
amplifier Q4, this circuit reduces the APC control voltage
(RAMP) when the temperature of amplifi er Q3 and fi nal am-
plifi er Q4 rises. The MCU detects the temperature with the
thermistor (TH201) and controls the APC voltage (RAMP).
3-6. FAN action control circuit
The FAN action control circuit consists of the FAN and
switching transistor Q207. It is controlled by the MCU (X53-
449). If the FAN action is set to “Temperature”, the cooling
fan is turned ON or OFF according to temperature. If the
FAN action is set to “Continuous”, the cooling fan operates
continuously, but Q207 stays ON.
3-7. AVR circuit
The 13.6V power source (+B) is provided through connec-
tor CN201 to the Final unit (X45-393 A/3). +B is connected
to CN203 to supply the 13.6V power source for the TX-RX
unit (X57-795). +B is a power source for the “final ampli-
fi er”, “drive amplifi er” and fan. IC203 regulates the +B volt-
age to 8V. This 8V power source is connected to the FET
switches Q203, Q204, Q205, and Q206. Q204 and Q206
are controlled by the “8TC” signal from the I/O expander IC
which is in the TX-RX unit (X57-795). If “8TC” logic is high,
Q204 and Q206 turn on and supply the 8V power source
to the APC circuit and pre drive amplifi ers. Q203 and Q205
are controlled by the “ASWC” signal from the I/O expander
IC which is in the TX-RX unit (X57-795). If “ASWC” logic
is high, Q203 and Q205 turn on and supply the 8V power
source to the antenna switch circuit.
Fig. 13 AVR circuit /
图 13 AVR 电路
Drive AMP
SW
8TC
Q204,Q206
SW
ASWC
Q203,Q205
CN201
+B
from Final unit
(X45-393 B/3)
+B
to TX-RX unit
(X57-795)
Final AMP
FAB
8V AVR
IC203
80T
80SW
CN203
4. Control unit
The Control unit (X53-449) consists of the following cir-
cuits:
(1) MCU circuit
(2) Memory circuit
(3) DSP circuit
(4) Squelch circuit
(5) Power supply circuit
(6) Power supply voltage monitoring circuit
(7) 18.432MHz clock circuit
(8) Audio circuit
(9) Other circuit
CIRCUIT DESCRIPTION /
电路说明
3-5. 高温检测器电路
为防止毁坏放大器 Q3 和末级放大器 Q4，该电路在放大器
Q3 和末级放大器 Q4 的温度升高时降低 APC 控制电压 (RAMP)。
MCU 用热敏电阻 (TH201) 检测温度并控制 APC 电压 (RAMP)。
3-6. FAN 动作控制电路
F A N 动作控制电路由 F A N 和开关晶体管 Q207 组成。它由
MCU(X53-449) 控制。如果把 FAN 动作设为“Temperature( 温
度 )”
，冷却风扇将根据温度开启或关闭。如果把 F A N 动作设
为“Continuous( 连续 )”
，冷却风扇将连续运行，但 Q207 将
保持开启状态。
3-7. AVR 电路
13.6V 电源 (+B) 通过连接器 CN201 提供到末级单元 (X45-393
A/3)。+B 连接到 CN203，为 TX-RX 单元 (X57-795) 提供 13.6V
电源。+ B 是“末级放大器”、
“驱动放大器”和风扇的电源。
IC203 将 +B 电压调节到 8V。该 8V 电源连接到 FET 开关 Q203、
Q204、Q205 和 Q206。Q204 和 Q206 由 T X - R X 单元 ( X57-795)
内 I / O 扩展器 I C 的“8T C”信号控制。如果“8T C”逻辑高，
Q204 和 Q206 开启，并向 A P C 电路和预驱动放大器提供 8V 电
源。Q203 和 Q205 由 TX-RX 单元 (X57-795) 内 I/O 扩展器 IC
的“ASWC”信号控制。如果“ASWC”逻辑高，Q203 和 Q205 开
启，并向天线开关电路提供 8V 电源。
4. 控制单元
控制单元 (X53-449) 由以下电路组成 ：
(1) MCU 电路
(2) 存储电路
(3) DSP 电路
(4) 静噪电路
(5) 电源电路
(6) 电源电压监测电路
(7) 18.432MHz 时钟电路
(8) 音频电路
(9) 其他电路
