使用CXA1691制作HX218收音机

使用CXA1691制作HX218收音机 HX218集成电路收音机安装与调试 仅用于教学 ?1. 概述 一、实训目的: 1、 学习收音机的装配与调试。 2、 提高对整机电路图与电路板图的识读能力。 3、 掌握收音机生产工艺流程，提高焊接与装配工艺水平。 4、 通过收音机组装、调试、检修，使学生提高故障分析能力和动手能力，为更高端的家用电子产品维修打下坚实的理论和实践基础。 二、实训内容: 1、 HX218集成电路收音机电路原理分析。 2( 收音机元器件识别与测量。 3( 电路图与印制电路板的对应。 4( 掌握印制电路板的组装及焊接工艺。 5( 进行AM、FM中频、覆盖的调试及统调和整机测试。 6( 收音机电路工作点的测量。 7( 故障判断及排除。 三、实训基本要求: 1、 会识别、检测元器件并判别其质量。 2、 能独立识读电路图和印制板图并完成各测试点的测量与整机安装。 3、 会排除在调试与装配过程中可能出现的问题与故障。 4、 所制作的产品电器性能指标应能满足三级机水平(国标)，具体如下: ? 接收频率范围: AM 535~1605KHZ FM 87~108MHZ ? 接收灵敏度: AM 达国家C类标准 FM 优于μV级 ? 输出功率 大于100mW ? 供电电源: DC 3V ?2. 收音机的基本工作原理 1、 收音机的电路结构种类有很多，早期生产的收音机多为分立元件电路，目前基本上都采用了大规模 集成电路为核心的电路(本机电路采用日本索尼公司生产的调频调幅专用集成电路CXA1691M，国 产型号为CD1691M)。集成电路收音机的特点是:结构比较简单，性能指标优越，体积小等优点。 AM/FM型的收音机电路可用如图1所示的方框图来表示。收音机通过调谐回路选出所需的电台， 送到变频器与本机振荡电路送出的本振信号进行混频，然后选出差频作为中频输出(我国 规定 关于下班后关闭电源的规定党章中关于入党时间的规定公务员考核规定下载规定办法文件下载宁波关于闷顶的规定 的 AM中频为465KHZ，FM中频为10.7MHZ)，中频信号经过检波器检波后输出调制信号(低频信 号)，调制信号(低频信号)经低频放大、功率放大后获得足够的电流和电压，即功率，再推动喇 叭发出响亮的声音。 图1 HX218AM/FM收音机电路方框图 2、本实训中采用的收音机是一种50型的AM/FM二波段的收音机，此收音机电路主要由大规模集成电路CXA1691M(CD1691M)组成。由于集成电路内部不便制作电感、电容和大电阻以及可调元件，meters village between road hardening, 11 km of pass group Highway, livelihood project; ordered advance XX finished pupils canteen, and wangji alone finished small teaching floor, and wangji alone finished pupils canteen, and ancient Dang "culture tourism features village", and wangji alone village and Bula village River suspension, and Bula village la Los end of pass group Highway, and XX Meters village debris flow disaster control, building project; started has victims will LOS, wood child moving, and autumn baby, pass group highway construction project; solid do "a water two dirt" regulation, and wood added Jia village, XING side fumin, and XX meters village pass village Highway hardening, and ancient Dang village disaster Hou traffic reconstruction, and Bula village whole village advance, and day care center, major project of early work. Second, develop eco-agriculture construction of the Canyon. Economic development of eco-agricultural construction in an important position, accelerated "8321" works completed caoguo 23700 acres planted, bubble 4125 acres planted walnuts, sumac 4000 acres planted, Yun Huang Lian 6040 acres planted, tea-oil tree planting 8887.8 acres. To cultivate new economic growth points, good farmers ' well-off society of the industrial base. Third, start a poverty alleviation project. Storming the headquarters was established, well-organized, well arranged, formation of 7 supporting task force launched the poverty file state cards work in a timely manner, the task force entered the village door communication policy, mobilization mass base, making poverty eradication plan, and find out about poverty, assist in the implementation of projects 故外围元件多以电感、电容和电阻及可调元件为主，组成各种控制、谐振、供电、滤波、耦合等电路。50型收音机电路图如图2所示。CXA1691M(CD1691M)内部电路图如图3所示。 图 2 HX218AM/FM型收音机电路图 图3 CXA1691M(CD1691M)内部方框图 n of projectstion policy, mobilization mass base, making poverty eradication plan, and find out about poverty, assist in the implementatiothe task force entered the village door communica organized, well arranged, formation of 7 supporting task force launched the poverty file state cards work in a timely manner,-a poverty alleviation project. Storming the headquarters was established, well off society of the industrial base. Third, start-oil tree planting 8887.8 acres. To cultivate new economic growth points, good farmers ' well-res planted, bubble 4125 acres planted walnuts, sumac 4000 acres planted, Yun Huang Lian 6040 acres planted, teaagricultural construction in an important position, accelerated "8321" works completed caoguo 23700 ac-agriculture construction of the Canyon. Economic development of eco-illage advance, and day care center, major project of early work. Second, develop ecoole vers village pass village Highway hardening, and ancient Dang village disaster Hou traffic reconstruction, and Bula village whhighway construction project; solid do "a water two dirt" regulation, and wood added Jia village, XING side fumin, and XX met group illage debris flow disaster control, building project; started has victims will LOS, wood child moving, and autumn baby, passnd wangji alone village and Bula village River suspension, and Bula village la Los end of pass group Highway, and XX Meters vge", aone finished small teaching floor, and wangji alone finished pupils canteen, and ancient Dang "culture tourism features villaen road hardening, 11 km of pass group Highway, livelihood project; ordered advance XX finished pupils canteen, and wangji almeters village betwe2 下面分别介绍收音机电路各功能块电路的作用。 (1)输入调谐(即选台)与变频 由于同一时间内广播电台很多，收音机天线接收到的不仅仅是一个电台的信号，是N个电台的信号。由于各个电台发射的载波频率均不相同，收音机的选频回路通过调谐，改变自身的振荡频率，当振荡频率与某电台的载波频率相同时，即可选中该电台的无线信号，从而完成选台。(串联谐振原理) 由于我们采用的是超外差式收音，选出的信号并不立即送到检波级，而是要进行频率的变换(即变频，目的是让收音机整个频段内的电台放大量基本一致，因为频率稳定放大倍数也就相对稳定)。利用本机振荡产生的频率与外来接收到的信号进行混频，选出差频，即获得固定的中频信号(AM的中频为465KHz，FM的中频为10.7MHz)。 图2所示收音机电路中，这部分电路有四个LC调谐回路，带箭头用虚线连在一起的是一只四联可变电容器CBM-443DF，其中CA与L1并联是调幅波段的输入回路(选台回路)、CB与T1相联的是调幅波段本机振荡电路，C7(120P)是一只垫振电容，把本振频率垫高，使本振电路频率比输入回路频率高465KHZ， CC与L2并联的是调频波段的输入回路(选台回路)，CD与L3并联为FM(调频)波段本振回路，和可变电容并联的分别是与它们适配的微调电容，用作统调。K2是波段开关，与集成电路“15”脚内部的电子开关配合完成波段转换，开关闭合是低电平为调幅波段，开关断开是高电平为调频波段。以上元件与集成电路(IC)内部有关电路一起构成调谐和本机振荡电路，变频功能基本由IC内部完成。 (2)中频放大与检波 作用:将选台、变频后的中频调制信号(调幅为465KHZ，调频为10.7M)送入中频放大电路进行中频放大，然后再进行解调，取出低频调制信号，即所需要的音频信号。 在图2电路中，中频放大电路的特征是具有“中周(中频变压器)”调谐电路或中频陶瓷滤波器。IC内部变频电路送出的中频信号从“14”脚输出，10.7MHz的调频中频信号经三端陶瓷滤波器CF2选出送往IC的“17”脚，465kHz的调幅中频信号经R1和T3中周，再经过CF1三端陶瓷滤波器选出送往IC的“16”脚，中频信号进入IC内部进行放大并检波，从“23”脚输出音频信号。鉴频(调频检波)和调幅检波电路都在IC内部。IC的“23-24”脚之间的电容C15是检波后得到的音频信号耦合到音频功率放大输入端的耦合电容(通交隔直，让交流的音频信号通过，直流分量隔离)， “2”脚外接的C9和T2是外接FM鉴频网络。 (3)低频放大与功率放大 作用:解调后得到的音频信号经低频和功率放大电路放大后送到扬声器或耳机，完成电声转换。图2电路中IC的“1”、“3”、“4”、“24,28”脚内部都是低频放大电路。“1”脚为静噪滤波，接有电容C10(0.022UF)，“3”脚所接电容C8(4.7UF)为功率放大电路的负反馈电容，“4”脚为直流音量控制端(改变引脚电位来改变内部差动放大器的放大倍数)，外接音量控制电位器中心抽头。IC的“25”脚接的C18(10UF)是功率放大电路的自举电容，以提高OTL功放电路的输出动态范围，“26”脚为功放电路供电端，外接C19(100UF)和C17(0.1UF)分别为电源的低频滤波和高频滤波电容。音频信号经“24”脚输入到IC中进行功率放大，放大后的音频信号从“27”脚输出，经C16(100U)耦合送到扬声器或耳机发声，C20(0.1UF)是一只高频滤波电容，防止高频成分送入扬声器。 (4)电源及其他电路 本机的电源部分包括有两节1.5 V电池、“26”脚外围的低频滤波电容C19(100UF)、C17(0.1UF)电源高频滤波电容，“8”脚外围的低频去耦滤波电容C2(10U)，电源高频滤波电容C3(0.22UF)及由音量电位器连动的电源开关K1，R3和LED构成电源指示电路。 “21”脚外围的C12(4.7UF)、“22”脚外围的C13(10UF)是自动增益控制(AGC)电路滤波电容。此外，为了防止各部分电路 -oil tree planting 8887.8 acres. To cultivate new economic growth points, good farmers ' well-an 6040 acres planted, tea5 acres planted walnuts, sumac 4000 acres planted, Yun Huang Liagricultural construction in an important position, accelerated "8321" works completed caoguo 23700 acres planted, bubble 412-agriculture construction of the Canyon. Economic development of eco-p ecoffic reconstruction, and Bula village whole village advance, and day care center, major project of early work. Second, develoJia village, XING side fumin, and XX meters village pass village Highway hardening, and ancient Dang village disaster Hou tradded od child moving, and autumn baby, pass group highway construction project; solid do "a water two dirt" regulation, and wood aof pass group Highway, and XX Meters village debris flow disaster control, building project; started has victims will LOS, wo s endt Dang "culture tourism features village", and wangji alone village and Bula village River suspension, and Bula village la Lofinished pupils canteen, and wangji alone finished small teaching floor, and wangji alone finished pupils canteen, and ancien meters village between road hardening, 11 km of pass group Highway, livelihood project; ordered advance XXut poverty, assist in the implementation of projectsut abotask force entered the village door communication policy, mobilization mass base, making poverty eradication plan, and find oized, well arranged, formation of 7 supporting task force launched the poverty file state cards work in a timely manner, the organ-welloff society of the industrial base. Third, start a poverty alleviation project. Storming the headquarters was established, 3 的相互干扰，IC内部各部分的电路都单独接地，并通过多个引脚与外电路的地相接，如“13” 脚是前置电路地，“28”脚是功放电路地。 (5)天线接收部分 CXAl691M(CDl691M)内部还设有调谐高放电路，目的是提高灵敏度。拉杆天线收到的调频电磁波由C1耦合进入“12”脚调频FM高放输入，再进行混频。调幅部分则由天线磁棒汇聚 接收电磁波，经L1的次级线圈进入变频电路。 ?3. 收音机电路板的装配 1、收音机元件清单: 序材料名称 型号/规格 位号 数量 号 1 CXA1691BM IC 集成块 1块 2 LED 发光二极管 φ3红 1支 455B 3 CF1 三端陶瓷滤波器 1支 10.7MHZ 4 CF2 三端陶瓷滤波器 1支 5 T1 中波振荡变压器 红色(中振) 1支 6 T3 中波中频变压器 黑色(465) 1支 7 T2 调频中频滤波器 绿色10.7MHZ 1只 8 L1 磁棒线圈 55×13×5mm 1套 9 L2 调频天线线圈 φ6×4圈 1支 1L3 调频振荡线圈 φ3×6圈 1支 0 11 330 R3 碳膜电阻 1支 1碳膜电阻 2K、100K R1、R2 各1支 2 15K 电位器 RP(K1) 1支 3 1瓷片电容 1P、10P C6、C9 各 1支 4 1瓷片电容 15P、18P C4、C5 各1支 5 1 瓷片电容 30P、121 C1、C7 各1支 6 103 1C11 瓷片电容 1支 7 1瓷片电容 223或203 C3、C10 2支 8 1104 瓷片电容 C17、C20 2支 9 20.47UF C15 电解电容 1支 0 24.7UF 电解电容 C8、C12 2支 1 10UF 2 电解电容 C2、C13、C18 3支 2 2100UF 电解电容 C16、C19 2支 organized, well arranged, formation of 7 supporting task force launched the poverty file state cards work in a timely manner,-a poverty alleviation project. Storming the headquarters was established, well off society of the industrial base. Third, start-oil tree planting 8887.8 acres. To cultivate new economic growth points, good farmers ' well-res planted, bubble 4125 acres planted walnuts, sumac 4000 acres planted, Yun Huang Lian 6040 acres planted, teaagricultural construction in an important position, accelerated "8321" works completed caoguo 23700 ac-agriculture construction of the Canyon. Economic development of eco-illage advance, and day care center, major project of early work. Second, develop ecoole vers village pass village Highway hardening, and ancient Dang village disaster Hou traffic reconstruction, and Bula village whhighway construction project; solid do "a water two dirt" regulation, and wood added Jia village, XING side fumin, and XX met group illage debris flow disaster control, building project; started has victims will LOS, wood child moving, and autumn baby, passnd wangji alone village and Bula village River suspension, and Bula village la Los end of pass group Highway, and XX Meters vge", aone finished small teaching floor, and wangji alone finished pupils canteen, and ancient Dang "culture tourism features villaen road hardening, 11 km of pass group Highway, livelihood project; ordered advance XX finished pupils canteen, and wangji almeters village betwen of projectstion policy, mobilization mass base, making poverty eradication plan, and find out about poverty, assist in the implementatiothe task force entered the village door communica4 3 2SL 四联电容器 CBM-443DF 1支 4 2BL 扬声器 φ58mm 1个 5 2K2 波段开关 1支 6 2TX 拉杆天线 一根 7 2 耳机插座 φ2.5mm 1个 8 2 印刷电路板 1块 9 3 刻度盘 1块 0 3 图纸装配说明书 1份 1 3连体簧、负极片、正极片 3件 1套 2 3 连接带线 电池喇叭天线、J 6根 3 3 平机螺丝 φ2.5×5 4粒 4 3 自攻螺丝 φ2×5 1粒 5 3 平机螺丝 φ1.6×5φ2×8 1粒 6 3 焊片、螺母 φ2.5φ2.0 各1个 7 3 前后盖、大小拨盘、磁棒支 1套 8 架 2、 收音机的装配 电路板元件的插件图如图4。 印刷电路板的装配是整机质量的关键，装配质量的好坏对收音机的性能有很大的影响。因此印制电路板装配总的要求是:?元器件在装配前务必检查其质量好坏，确保元器件是正常能使用的; ? 装插位置务必正确，不能有插错，漏插; ? 焊点要光滑、无虚焊、假焊和连焊。 (1)元器件的装插焊接:应遵循先小后大，先轻后重，先低后高，先外围再集成电路的原则。我这里还介绍一种办法就是:以集成电路为中心，从“1—28”脚外围电路元件依次一一清理的办法进行装配，这样有利于电路熟悉和装配顺利进行。 (2)瓷介电容、电解电容及三极管等元件立式安装:引线不能太长，否则会降低元器件的稳定性，而且容易短路，也会导致分布参数受到影响而影响整机效果;但也不能过短，以免焊接时因过热损坏元器件。一般要求距离电路板面2mm，并且要注意电解电容的正负极性，不能插错。 (3)可调电容器(四联)的装插:六脚应插到位，不要插反(中心抽头多一个引脚的一面为调频部分可变电容)，应该先上螺钉再进行焊接。 an 6040 acres planted, tea5 acres planted walnuts, sumac 4000 acres planted, Yun Huang Liagricultural construction in an important position, accelerated "8321" works completed caoguo 23700 acres planted, bubble 412-agriculture construction of the Canyon. Economic development of eco-p ecoffic reconstruction, and Bula village whole village advance, and day care center, major project of early work. Second, develoJia village, XING side fumin, and XX meters village pass village Highway hardening, and ancient Dang village disaster Hou tradded od child moving, and autumn baby, pass group highway construction project; solid do "a water two dirt" regulation, and wood aof pass group Highway, and XX Meters village debris flow disaster control, building project; started has victims will LOS, wo s endt Dang "culture tourism features village", and wangji alone village and Bula village River suspension, and Bula village la Lofinished pupils canteen, and wangji alone finished small teaching floor, and wangji alone finished pupils canteen, and ancien meters village between road hardening, 11 km of pass group Highway, livelihood project; ordered advance XXut poverty, assist in the implementation of projectsut abotask force entered the village door communication policy, mobilization mass base, making poverty eradication plan, and find oized, well arranged, formation of 7 supporting task force launched the poverty file state cards work in a timely manner, the organ-welloff society of the industrial base. Third, start a poverty alleviation project. Storming the headquarters was established, -oil tree planting 8887.8 acres. To cultivate new economic growth points, good farmers ' well-5 (4)音量开关电位器的安装:首先用铜铆钉固定两边开关脚，然后再进行焊接。使电位器与线路板平行，在焊电位器的三个焊接片时，应在短时间内完成，否则易焊坏电位器的动触片、从而造成音量电位器不起作用而失调或接触不良。 (5)集成电路的焊接:CD1691M为双列28脚扁平式封装，焊接时首先要弄清引线脚的排列顺序，并与线路板上的焊盘引脚对准，核对无误后，先焊接1、15脚用于固定IC，然后再重复检查，确认后再焊接其余脚位。由于IC引线脚较密，焊接完后要检查有无虚焊，连焊等现象，确保焊接质量，否则会有损坏IC的危险。 图4 印刷电路板图 ?4. 收音机电路板的调整 1、收音机电路板的调整原理 收音机的调整是收音机实训的其中一个重要内容，有些同学一焊接完，就以为大功告成，特别是有些同学还能收到一两个电台，就忽视了后面的实训，这是非常错误的指导思想。我们一定要重视收音机的调试部分的实训。 在调试前必须确保收音机能接收到沙沙的电流声(或电台)，若听不到电流声或电台，应先检查电路的焊接有无错误、元件有无损坏，直到能听到声音才可做以下的调整实验。 超外差收音机的调整有三种: 1.调中频——即是调中频调谐回路 中放电路是决定收音电路的灵敏度和选择性的关键所在，它的性能优劣直接决定了整 机性能的好坏。调整中频变压器，使之谐振在AM/465kHz(或FM/10.7MHz)频率，这就是 中放电路的调整任务。 2.调覆盖——即是调本振谐振回路 超外差收音机电路接收信号的频率范围与机壳刻度上的频率标志应一致，所以，要进行 校准调整，也叫调覆盖。 在超外差收音机中，决定接收频率的是本机振荡频率与中频频率的差值，而不是输入回 路的频率，因此，调覆盖实质是调本振频率和中频频率之差。因此调覆盖即调整本振回路， 使它比收音机频率刻度盘的指示频率高AM/465kHz(或FM/10.7MHz)。在本振电路中，改变 振荡线圈的电感值(即调节磁芯)可以较为明显地改变低频端的振荡频率(但对高频端也有 影响)。改变振荡微调电容的电容量，可以明显地改变高频端的振荡频率。 organized, well arranged, formation of 7 supporting task force launched the poverty file state cards work in a timely manner,-a poverty alleviation project. Storming the headquarters was established, well off society of the industrial base. Third, start-oil tree planting 8887.8 acres. To cultivate new economic growth points, good farmers ' well-res planted, bubble 4125 acres planted walnuts, sumac 4000 acres planted, Yun Huang Lian 6040 acres planted, teaagricultural construction in an important position, accelerated "8321" works completed caoguo 23700 ac-agriculture construction of the Canyon. Economic development of eco-illage advance, and day care center, major project of early work. Second, develop ecoole vers village pass village Highway hardening, and ancient Dang village disaster Hou traffic reconstruction, and Bula village whhighway construction project; solid do "a water two dirt" regulation, and wood added Jia village, XING side fumin, and XX met group illage debris flow disaster control, building project; started has victims will LOS, wood child moving, and autumn baby, passnd wangji alone village and Bula village River suspension, and Bula village la Los end of pass group Highway, and XX Meters vge", aone finished small teaching floor, and wangji alone finished pupils canteen, and ancient Dang "culture tourism features villaen road hardening, 11 km of pass group Highway, livelihood project; ordered advance XX finished pupils canteen, and wangji almeters village betwen of projectstion policy, mobilization mass base, making poverty eradication plan, and find out about poverty, assist in the implementatiothe task force entered the village door communica6 3.统调——即是调输入回路 统调又称为调整灵敏度，本机振荡频率与中频频率确定了接收的外来信号频率，输入回路与外来信号的频率的谐振与否，决定了超外差收音机的灵敏度和选择性(即选台功能)，因此，调整输入回路使它与外来信号频率谐振，可以使收音机灵敏度高，选择性较好。调整输入回路的选择性也称为调补偿或调跟踪，但是在外差式收音电路中，调整输入谐振回路的选择性会影响灵敏度，因此，调整谐振回路的谐振频率主要是调整灵敏度，使整机各波段的调谐点一致。 调整时，低端调输入回路线圈在磁棒上的位置，高端调天线接收部分的与输入回路并联的微调电容。 2、收音机电路板的调整的实验 (1)调幅部分的调整 ?中频放大电路的调整——调AM中周 用调幅高频信号发生器进行调整方法如下: 图5 中频变压器调整仪器连接示意图 , 调整时，整机置中波AM收音位置，调整前按图5配置仪表和接线或直接听收音机 的喇叭输出声音。 , 将音量电位器置于最大位置，将收音机调谐到无电台广播又无其它干扰的地 方(或者将可调电容调到最大，即接收低频端)，必要时可将振荡线圈初级或次级短 路，使之停振。 , 使高频信号发生器的输出载波频率为465kHz，载波的输出电平为99dB，调 制信号的频率为1000Hz，调 制度 关于办公室下班关闭电源制度矿山事故隐患举报和奖励制度制度下载人事管理制度doc盘点制度下载 为30,的调幅信号接入IC的“l4”脚，也可以通 过圆环天线发射或接入输入回路(图5所示)，由磁性天线接收作为调整的输入信 号。 , 用无感螺丝刀微微旋转中频变压器(黑色中周，T3)的磁帽向上或向下调整(调 整前最好做好记号，记住原来的位置)，使示波器显示的波形幅度最大，若波形出 现平顶，应减小信号发生器的输出，同时再细调一次。在调整中频变压器时也可以 用喇叭监听，当喇叭里能听到1000Hz的音频信号，且声音最大，音色纯正，此时可 认为中频变压器调整到最佳状态。 agricultural construction in an important position, accelerated "8321" works completed caoguo 23700 acres planted, bubble 412-agriculture construction of the Canyon. Economic development of eco-p ecoffic reconstruction, and Bula village whole village advance, and day care center, major project of early work. Second, develoJia village, XING side fumin, and XX meters village pass village Highway hardening, and ancient Dang village disaster Hou tradded od child moving, and autumn baby, pass group highway construction project; solid do "a water two dirt" regulation, and wood aof pass group Highway, and XX Meters village debris flow disaster control, building project; started has victims will LOS, wo s endt Dang "culture tourism features village", and wangji alone village and Bula village River suspension, and Bula village la Lofinished pupils canteen, and wangji alone finished small teaching floor, and wangji alone finished pupils canteen, and ancien meters village between road hardening, 11 km of pass group Highway, livelihood project; ordered advance XXut poverty, assist in the implementation of projectsut abotask force entered the village door communication policy, mobilization mass base, making poverty eradication plan, and find oized, well arranged, formation of 7 supporting task force launched the poverty file state cards work in a timely manner, the organ-welloff society of the industrial base. Third, start a poverty alleviation project. Storming the headquarters was established, -oil tree planting 8887.8 acres. To cultivate new economic growth points, good farmers ' well-an 6040 acres planted, tea5 acres planted walnuts, sumac 4000 acres planted, Yun Huang Li7 提示 若中频放大器的谐振频率偏离465kHz较大时～示波器可能没有输出或幅度极小～这时可左右偏调输入调幅信号的频率～使示波器有输出～待找到谐振点后～再把调幅高频信号发生器的频率逐步向465kHz靠拢～同时调整中频变压器～直到把频率调整在465kHz。 在调整过程中～必须注意当整机输出信号逐步增大后～应尽可能减小输入信号电平。这是因为收音部分的自动增益控制是通过改变直流工作点来控制晶体管增益的～而直流工作点的变化又会引起晶体管极间电容的变化～从而引起回路谐振频率的偏离～因此必须把输入信号电平尽可能降低。 ?调整接收范围(频率覆盖)——调AM的电感和电容 按国标规定中波段的接收频率范围规定为525,1605kHz，实际调整时留有一定的余量，一般为515,1625kHz。我们将对515kHz的调整叫低端频率调整，对1625kHz的调整叫高端频率调整。用高频信号发生器调整频率接收范围的方法是: 低端频率调整: , ? 调整时，整机置中波AM收音位置，调整前按图5配置仪表和接线或直接听收音机 的喇叭输出声音，将音量电位器置于最大位置。 , ? 将可变电容器(调谐双联)旋到容量最大处，即机壳指针对准频率刻度的最低 频端，将收音机调谐到无电台广播又无其它干扰的地方。 , ? 使高频信号发生器的输出频率为515kHz，载波的输出电平为99dB，调制信 号的频率为1000Hz，调制度为30,的高频调幅信号接入收音机的AM磁性天线输入 端(即IC的“l0”脚)，作为调整的输入信号。 , ? 用无感螺丝刀调整中波振荡线圈的磁芯(红色中周)，如下图6所示，以改变线 圈的电感量，使示波器出现1000Hz波形，并使波形最大。或直接监听收音机的声音， 使收音机发出的声音最响最清晰。 高端频率调整: , ? 将整机的可变电容器置容量最小处，这时机壳指针应对准频率刻度的最高频 端。 , ?使高频信号发生器的输出频率为1625kHz，载波的输出电平为99dB，调制信号 的频率为1000Hz，调制度为30,的高频调幅信号接入收音机的AM磁性天线输入端 (即IC的“l0”脚)，作为调整的输入信号。 , ?调节并联在振荡回路上的，和CB并联的补偿电容器，如图6所示，使示波器的 波形最大(或喇叭声音最响)。 这样接收电路的频率覆盖就达到515,1625kHz的要求了，但因为高低频端的谐振频率 的调整相互牵制，所以必须反复调节多次，直到整机的接收频率范围符合要求为止。 图 6 调整频率接收范围 ?、统调 organized, well arranged, formation of 7 supporting task force launched the poverty file state cards work in a timely manner,-a poverty alleviation project. Storming the headquarters was established, well off society of the industrial base. Third, start-oil tree planting 8887.8 acres. To cultivate new economic growth points, good farmers ' well-res planted, bubble 4125 acres planted walnuts, sumac 4000 acres planted, Yun Huang Lian 6040 acres planted, teaagricultural construction in an important position, accelerated "8321" works completed caoguo 23700 ac-agriculture construction of the Canyon. Economic development of eco-illage advance, and day care center, major project of early work. Second, develop ecoole vers village pass village Highway hardening, and ancient Dang village disaster Hou traffic reconstruction, and Bula village whhighway construction project; solid do "a water two dirt" regulation, and wood added Jia village, XING side fumin, and XX met group illage debris flow disaster control, building project; started has victims will LOS, wood child moving, and autumn baby, passnd wangji alone village and Bula village River suspension, and Bula village la Los end of pass group Highway, and XX Meters vge", aone finished small teaching floor, and wangji alone finished pupils canteen, and ancient Dang "culture tourism features villaen road hardening, 11 km of pass group Highway, livelihood project; ordered advance XX finished pupils canteen, and wangji almeters village betwen of projectstion policy, mobilization mass base, making poverty eradication plan, and find out about poverty, assist in the implementatiothe task force entered the village door communica 8 中波段的统调点为630kHZ，1000kHz，1400kHz。 , 调整时，整机置中波AM收音位置，调整前按上图5配置仪表和接线或直接听收音机 的喇叭输出声音。将音量电位器置于最大位置。 先统调低频率630kHz端。 , 由调幅高频信号发生器通过圆环天线送出频率为630kHz ，电平为99dB，调制信 ,的高频调幅信号作为调整的输入信号(或接入收号的频率为1000Hz，调制度为30 音机的AM磁性天线输入端，即IC的“l0”脚)。将接收机调谐到该630kHz频率上， 然后调整磁性天线线圈在磁棒上的位置，如图5所示，使整机输出波型幅度最大(或 听到的收音机的声音最响最清晰)。 , 接着统调高频端频率点，由调幅高频信号发生1400kHz的信号，将整机调谐到 该频率上，然后用无感螺刀调节磁性天线回路的补偿电容(在四联可变电容上面)， 如图 7所示，使整机输出波形最大(或听到的收音机的声音最响最清晰)。 图 7 中波统调 提示 统调结果正确与否～我们可以用铜、铁棒来鉴别。当统调正确时～用铜铁棒的两头分别靠近磁性天线线圈后～整机输出都会下降,即收音机的声音变小,这种现象称为“铜降”和“铁降”～否则称为“铜升”和“铁升”。若“铁升”～则说明电感量不足～应增加电感量～将线圈往磁棒中心移动～若“铜升”～则反之。在高频端～若“铁升”应增加电容量:若“铜升”～则应减小电容量。按上述方法反复进行调整～直至高频端和低频端都完全统调好为止～在一般情况下～低频端和高频端统调好后～中频端1000kHz的失谐不会太大～至此～三点频率跟踪已完成。 要注意的是～在统调时输入的调幅信号不宜太大～否则不易调到峰点。另外磁棒线圈统调正确后应用蜡加以固封～以免松动～影响统调效果。 2、调频部分的调整 ?、中频放大电路的调整 与调幅收音电路相类似，调频收音电路的中频放大级也要进行调整。 用调频高频信号发生器调整的方法如下: , 调整时，整机置FM收音位置，调整前按图9配置仪表和接线或直接听收音机的喇叭 输出声音。 , 将音量电位器置于最大位置，将收音机调谐到无电台广播又无其它干扰的地方。 an 6040 acres planted, tea5 acres planted walnuts, sumac 4000 acres planted, Yun Huang Liagricultural construction in an important position, accelerated "8321" works completed caoguo 23700 acres planted, bubble 412-agriculture construction of the Canyon. Economic development of eco-p ecoffic reconstruction, and Bula village whole village advance, and day care center, major project of early work. Second, develoJia village, XING side fumin, and XX meters village pass village Highway hardening, and ancient Dang village disaster Hou tradded od child moving, and autumn baby, pass group highway construction project; solid do "a water two dirt" regulation, and wood aof pass group Highway, and XX Meters village debris flow disaster control, building project; started has victims will LOS, wo s endt Dang "culture tourism features village", and wangji alone village and Bula village River suspension, and Bula village la Lofinished pupils canteen, and wangji alone finished small teaching floor, and wangji alone finished pupils canteen, and ancien meters village between road hardening, 11 km of pass group Highway, livelihood project; ordered advance XXut poverty, assist in the implementation of projectsut abotask force entered the village door communication policy, mobilization mass base, making poverty eradication plan, and find oized, well arranged, formation of 7 supporting task force launched the poverty file state cards work in a timely manner, the organ-welloff society of the industrial base. Third, start a poverty alleviation project. Storming the headquarters was established, -oil tree planting 8887.8 acres. To cultivate new economic growth points, good farmers ' well-9 , 高频信号发生器输出频率为10.7MHz，电平为99dB，调制频率为1000Hz，频偏为 ?22.5kHz的调频信号。对于分立元件组成的调谐器，10.7MHz信号经中频输入电路 引出，用夹子夹在混频管的塑料壳上，由电路中的分布电容耦合到电路中去，对于集 成电路组成的调谐器，10.7MHZ的中频调频信号可直接加到调频天线连接的信号输入 端。 然后由小至大调节信号发生器的输出信号的幅值，直至示波器里能在收音机的输 出端看到lkHz的音频信号，此时用无感螺刀反复调整中周T2(绿色)，使输出为最大， 而且波形不失真，同时，注意当整机输出信号增大时，适当减小输入信号电平，再进行 调整，最后将信号发生器的调制方式，由调频转向调幅，调制频率仍为1kHz，调制度 为30,，调节绿色中周，使输出最小，这样反复进行调整，使整机在接收10.7MHz中 频调频信号时的输出最大，而在接收10.7MHz调幅信号时输出最小，即两点重合。在 调整中频变压器时也可以用喇叭监听，当喇叭里能听到1000Hz的音频信号，且声音 最大，音色纯正，此时可认为中频变压器调整到最佳状态。 图 8 用调频高频信号发生器调整中频放大级 ?、 调整调频段的接收范围(频率覆盖)——调FM的电感和电容 调频广播的接收范围规定为87,108MHZ，实际调整时一般为86.2—108.5MHz。这里介绍用信 号发生器进行调整的方法: , 调整时，整机置中波FM收音位置，将音量电位器置于最大位置，调整前按图8配置仪 表和接线或直接听收音机的喇叭输出声音。 低端频率调整: , 将可变电容器(调谐双联)旋到容量最大处，即机壳指针对准频率刻度的最低频端， 将收音机调谐到无电台广播又无其它干扰的地方。 , 使调频高频信号发生器送出调制频率为1000Hz，频偏为22.5kHz，电平为 30db(20uv)左右，频率为86.2MHz的调频信号，该信号经调频单信号标准模拟天线加到 整机拉杆天线的输入端。 , 在频率低频端调节L3振荡线圈，以改变线圈的电感量，使示波器出现1000Hz波形， 并使波形最大。或直接监听收音机的声音，使收音机发出的声音最响最清晰。 高端频率调整: , 将可变电容器(调谐双联)旋到容量最小处，即机壳指针对准频率刻度的最高频 端，将收音机调谐到无电台广播又无其它干扰的地方。 off society of the industrial base. Third, start-oil tree planting 8887.8 acres. To cultivate new economic growth points, good farmers ' well-res planted, bubble 4125 acres planted walnuts, sumac 4000 acres planted, Yun Huang Lian 6040 acres planted, teaagricultural construction in an important position, accelerated "8321" works completed caoguo 23700 ac-agriculture construction of the Canyon. Economic development of eco-illage advance, and day care center, major project of early work. Second, develop ecoole vers village pass village Highway hardening, and ancient Dang village disaster Hou traffic reconstruction, and Bula village whhighway construction project; solid do "a water two dirt" regulation, and wood added Jia village, XING side fumin, and XX met group illage debris flow disaster control, building project; started has victims will LOS, wood child moving, and autumn baby, passnd wangji alone village and Bula village River suspension, and Bula village la Los end of pass group Highway, and XX Meters vge", aone finished small teaching floor, and wangji alone finished pupils canteen, and ancient Dang "culture tourism features villaen road hardening, 11 km of pass group Highway, livelihood project; ordered advance XX finished pupils canteen, and wangji almeters village betwen of projectstion policy, mobilization mass base, making poverty eradication plan, and find out about poverty, assist in the implementatiothe task force entered the village door communica organized, well arranged, formation of 7 supporting task force launched the poverty file state cards work in a timely manner,-a poverty alleviation project. Storming the headquarters was established, well 10 , 使调频高频信号发生器送出调制频率为1000Hz，频偏为22.5kHz，电平为 30db(20uv)左右，频率为108.5MHz的调频信号。该信号经调频单信号标准模拟天 线加到整机拉杆天线的输入端。 , 在频率高端，调节振荡回路与CD并联的补偿电容。使示波器出现1000Hz波形， 并使波形最大。或直接监听收音机的声音，使收音机发出的声音最响最清晰。 , 由于高低频端的谐振频率的调整相互牵制较大，所以必须反复调节多次，直到 整机的接收频率范围符合要求为止。 提示调频振荡线圈一般为空心线圈～欲减小线圈的电感量～可将线圈拨得疏松些～ 欲增加线圈的电感量～可将线圈拨得紧密些。 这样接收电路的频率覆盖就达到87,108MHZ的要求了，但因为高低频端的谐振频率 的调整相互牵制，所以必须反复调节多次，直到整机的接收频率范围符合要求为止。 图 9 用调频高频信号发生器调整调频段的接收频率范围 ?、 统调灵敏度——调节L2的电感量和与CC并联的回路补偿电容的容量 调频波段的统调频率为89M、98M、106MHz，但一般统调低频端和高频端两点就可以了。 , 调整时，整机置中波FM收音位置，调整前按图 9配置仪表和接线(实际电路仅仅一只C1， 没有88M—108M的带通滤波器)或直接听收音机的喇叭输出声音， 将音量电位器置于最大位 置。 , 先统调低频率89MHz 端。 , 使调频高频信号发生器送出调制频率为1000Hz，频偏为22.5kHz，电平为26db(20uv) 左右，频率为89MHz 的调频信号。该信号经调频单信号标准模拟天线加到整机拉杆天线 的输入端。 , 调节的高频调谐回路线圈L2的电感量，使示波器显示输出最大。或直接监听收音机的 声音，使收音机发出的声音最响最清晰。 , 接着统调高频端频率点，使调频高频信号发生器送出调制1000Hz，频偏为22.5kHz， 电平为26db(20uv)左右，频率为106MHz的调频信号。该信号经调频单信号标准模拟 天线加到整机拉杆天线的输入端。 , 调节输入回路补偿电容(与CC并联的补偿电容)的容量，使整机输出波形最大(或听 到的收音机的声音最响最清晰)。 为了能达到较好的效果，需要耐心的反复地调节。 ?5. 思考题 welloff society of the industrial base. Third, start a poverty alleviation project. Storming the headquarters was established, -oil tree planting 8887.8 acres. To cultivate new economic growth points, good farmers ' well-an 6040 acres planted, tea5 acres planted walnuts, sumac 4000 acres planted, Yun Huang Liagricultural construction in an important position, accelerated "8321" works completed caoguo 23700 acres planted, bubble 412-agriculture construction of the Canyon. Economic development of eco-p ecoffic reconstruction, and Bula village whole village advance, and day care center, major project of early work. Second, develoJia village, XING side fumin, and XX meters village pass village Highway hardening, and ancient Dang village disaster Hou tradded od child moving, and autumn baby, pass group highway construction project; solid do "a water two dirt" regulation, and wood aof pass group Highway, and XX Meters village debris flow disaster control, building project; started has victims will LOS, wo s endt Dang "culture tourism features village", and wangji alone village and Bula village River suspension, and Bula village la Lofinished pupils canteen, and wangji alone finished small teaching floor, and wangji alone finished pupils canteen, and ancien meters village between road hardening, 11 km of pass group Highway, livelihood project; ordered advance XXut poverty, assist in the implementation of projectsut abotask force entered the village door communication policy, mobilization mass base, making poverty eradication plan, and find oized, well arranged, formation of 7 supporting task force launched the poverty file state cards work in a timely manner, the organ-11 1. 调整中波灵敏度时，信号源的环形天线与收音机的磁棒线圈应成什么角度,灵敏度统调 点一般选在哪几点,如何统调灵敏度? 2. 在调整收音机灵敏度时，信号源的输出幅度为什么不能太大, 3. 如中波收音机低端收台时声小，但用磁棒靠近则声音变大，试问低端统调好了吗?此时 天线电感是过大还是过小，应怎样调整为正确? 4. 收音机为什么要统调? 5. 调整AM、FM波段的频率覆盖范围，应采取几个步骤? tion policy, mobilization mass base, making poverty eradication plan, and find out about poverty, assist in the implementatiothe task force entered the village door communica organized, well arranged, formation of 7 supporting task force launched the poverty file state cards work in a timely manner,-a poverty alleviation project. Storming the headquarters was established, well off society of the industrial base. Third, start-oil tree planting 8887.8 acres. To cultivate new economic growth points, good farmers ' well-res planted, bubble 4125 acres planted walnuts, sumac 4000 acres planted, Yun Huang Lian 6040 acres planted, teaagricultural construction in an important position, accelerated "8321" works completed caoguo 23700 ac-agriculture construction of the Canyon. Economic development of eco-illage advance, and day care center, major project of early work. Second, develop ecoole vers village pass village Highway hardening, and ancient Dang village disaster Hou traffic reconstruction, and Bula village whhighway construction project; solid do "a water two dirt" regulation, and wood added Jia village, XING side fumin, and XX met group illage debris flow disaster control, building project; started has victims will LOS, wood child moving, and autumn baby, passnd wangji alone village and Bula village River suspension, and Bula village la Los end of pass group Highway, and XX Meters vge", aone finished small teaching floor, and wangji alone finished pupils canteen, and ancient Dang "culture tourism features villaen road hardening, 11 km of pass group Highway, livelihood project; ordered advance XX finished pupils canteen, and wangji almeters village betwen of projects12