Kenwood TK-3148 Service Manual

Also see for TK-3148: Service manual

Contents

TK-3148166. Control CircuitThe control circuit consists of MCU (IC309) and its periph-eral circuits. It controls the TX-RX unit and transfers data toand from the display unit. IC309 mainly performs the follow-ing;1) Switching between transmission and reception by PTTsignal input.2) Reading system, group, frequency, and program datafrom the memory circuit.3) Sending frequency program data to the PLL.4) Controlling squelch on/off by the DC voltage from thesquelch circuit.5) Controlling the audio mute circuit by decode data input.6) Transmitting tone and encode data.6-1. Memory circuitMemory circuit consists of the MCU (IC309) and a flashmemory (IC308), a fl ash memory has a capacity of 4M bitsthat contains the transceiver control program for the MCUand data such as transceiver channels and operating fea-tures.This program can be easily written from an external de-vices. Data. such as operating status, are programmed intothe EEPROM (IC310).• Flash MemoryNote: The flash memory stores the data containing theFPU (KPG-74D CPS) program, Security Number (MPT SerialNumber) and firmware program (User mode, Test mode,Tuning mode, etc.). This data must be reinstalled when re-placing the fl ash memory.• EEPROMNote: The EEPROM stores tuning data (Deviation, Squelch,etc.). Realign the transceiver after replacing the EEPROM.6-2. Low battery warningThe battery voltage is monitored by the MCU (IC309).When the battery voltage falls below the voltage set by theLow Battery Warning adjustment, the red LED flashes tonotify the operator that it is time to replace the battery. Ifthe battery voltage falls even more (approx. 6.1V), a beepsounds and transmission is stopped.Low battery warning Battery conditionThe red LED fl ashes duringtransmissionThe battery voltage is low but thetransceiver is still usable.The red LED fl ashes andcontinuous beep soundswhile PTT pressedThe battery voltage is low and thetransceiver is not usable to makecalls.6．控制电路控制电路由 M C U ( I C309) 和其外围电路组成。M C U 控制TX-RX 单元和发送到显示单元的数据以及从显示单元发送的数据。IC309 主要执行下述功能 :1) 通过 PTT 信号输出在发射和接收之间转换。2) 从存储器电路读取系统，组，频率和编程数据。3) 向 PLL 发送频率编程数据。4) 通过来自于静噪电路的直流电压控制静噪的开启 / 关闭。5) 通过解码数据输入控制音频静音电路。6) 发送音频和编码数据。6-1. 存储器电路记忆电路由 MCU(IC309) 和一块闪存 (IC308) 组成。闪存容量 4MB，载有 MCU 所需的收发机控制程序以及收发机信道、功能设置等数据。可以方便地使用外部设备写这个程序。工作状态等数据编写在 EEPROM(IC310) 中。• 闪存注释 : 闪存保存的数据包括 FPU(KPG-74D CPS) 程序，安全码(MPT 序列号 ) 和固件编程 ( 用户模式，测试模式，调谐模式等 )。当更换闪存时，必须重新安装数据。• EEPROM注释 : EEPROM 保存调谐数据 ( 频偏，静噪 )。更换 EEPROM 后重新调校对讲机。6-2. 电池低压告警通过 MCU(IC309) 监视电池电压。当电池的电压低于通过电池低压告警调整设定的电压时，红色指示灯闪烁以提示操作者更换电池。如果电池的电压继续降低 ( 大约 6.1V)，则发出beep 音并停止发送。电池低压告警电池状态发射过程中红色指示灯闪烁。电池电压降低但仍可使用对讲机。当按下 PTT 键时红色指示灯闪烁并且对讲机发出连续 beep 音。电池电压降低不能使用对讲机发出呼叫。MCU EEPROMFLASHIC309IC308 IC310Fig. 9 Memory circuit / 图 9 存储器电路CIRCUIT DESCRIPTION / 电路说明