Transcript AM-FM Radio
AM-FM Radio Superhet 108 Superheterodyne Principle • The superheterodyne principle was originally conceived in 1918 by Edwin Armstrong during WWI, • The concept was to overcome the deficiencies of Vacuum tube technology, Heterodyning • If a radio station were transmitting on 300 kHz and the oscillator were set to 400 kHz, as well as the original 300 kHz, the same station would be also heard on 100 kHz and 700 kHz. • Mixing two frequencies creates two new frequencies, – one at the sum of the two frequencies mixed (700), – and the other at their difference (100). • This is known as “heterodyning”. Assembly of the AM Radio • Assembly of the AM-FM Radio is broken down into 9 sections, – Section 1- Audio Amplifier, – Section 2- AM Detector and Automatic Gain Control (AGC) Stage, – Section 3- Second AM IF Amplifier, – Section 4- First AM IF Amplifier, – Section 5- AM Mixer, AM Oscillator, and AM Antenna, Assembly of the FM Radio • • • • Section 6- The FM Radio, Section 7- Second FM IF Amplifier, Section 8- First FM IF Amplifier, Section 9- FM RF Amplifier, Mixer, Oscillator, and Automatic Frequency Control (AFC), Testing • After assembling each section, you will test that section following the directions in the book, – Record all voltages, amperages, etc in your book, and on the Design Brief that is associated with that section, – Static Measurements (voltage, amperage) will be done with a Multimeter, • If your project fails that section test, then check each and every part that you installed and soldered, • Do not move to the next section until the radio passes testing for each section, Soldering • Read page 4 in the instruction manual, • Soldering is VERY important, follow the correct procedures explained and shown on page 4, • Excessive solder, Solder bridges, insufficient solder, or insufficient heat will cause a poor connection and keep your radio from functioning correctly, Component Parts • As you install the component parts, resistors, capacitors, test points, transistors, etc.) make sure you read each to insure that it is the correct component, • Check off each in your instruction book as you place it on the circuit board, • Pay attention to polarity of all the component parts, positive to positive, negative to negative, Design Briefs • The design briefs for this project are broken down by section, • While working on the radio project, additional design briefs for related material are to be completed, • As you complete each section, record your testing results in the instruction manual, and on the associated design brief. Then upload the design brief to the instructor via the classroom website, • The final design brief is a custom stand to display your completed radio, Radio Assignment 1 • Visit the following URL http://www.antiqueradios.com/superhet/ • Using the information found at this website (and others) create a PowerPoint that details the development of the superheterodyne radio, Radio Assignment 1 • The PowerPoint must: – Include detailed information on the development of the superheterodyne, – Include graphics/pictures, – Include a bibliography page, – Be “at least” 25 slides in length, – Use 10-12 point type, – Be saved in a webpage format, – Not include sound, – Be original material, (no cut and paste, except for pictures), – Be completed on or before January 29th , 2016. Today • Begin work on Radio Assignment 1, • Watch the video “History of Radio – Marconi”, – Video is available on the classroom website dashboard, click on the “Research Topics” button, – Complete the video worksheet,