Chapter 15:

Radio Frequency Interference

Objectives:

Students completing this lesson should be familiar with the causes of Radio Frequency Interference and how to prevent it.

Apparatus:

Handouts:

Lesson Plan:

  1. Go over questions from the Chapter 14 homework.

  2. Emphasize that is very important unit, especially if one is living cheek-to-jowl with one's neighbours in a modern subdivision with small lots, or worse still, living in an apartment house. The problem is further exacerbated by the proliferation of electronic devices in the modern home. Your students need to know and understand the various terms bandied about in the chapter. If possible use an HF receiver to show them examples of splattering.

  3. Use an HF transmitter to show TV interference on 80 metres and how a filter can alleviate this.

  4. Show how to make a filter that employs a toroid. Also, demonstrate how a snap-together core makes this task much easier.

  5. Show the students various types of commercially available filters: high-pass, low-pass, bandpass, band-stop, etc.

  6. The students need to be aware of the frequency ranges of the Amateur HF bands in order to do some of the Chapter 15 Quiz questions. This would be good topic for a quick review.

Homework:

  1. Read Chapter 15.

  2. Do Chapter 15 Quiz Questions

  3. Skim Chapter 16

Chapter 15 Quiz:

Printable copy of the Review Quiz

Answers to Chapter 15 Quiz
1 C 13 C 25 C 37 B 49 D
2 C 14 C 26 B 38 C 50 B
3 C 15 D 27 A 39 D 51 D
4 A 16 C 28 B 40 C 52 C
5 B 17 B 29 D 41 C 53 B
6 B 18 A 30 A 42 D 54 C
7 D 19 D 31 D 43 C 55 C
8 B 20 A 32 A 44 A 56 B
9 D 21 C 33 C 45 A 57 B
10 C 22 D 34 B 46 C * *
11 A 23 B 35 A 47 D * *
12 C 24 A 36 D 48 C * *

Overhead Slide Versions of the Diagrams

  1. Slide 1
    15.1   ¼ Wave Stub

  2. Slide 2   (Toroids)
    15.2 Toroid Core Choke
    15.3 Split Toroid Core

  3. Slide 3
    15.5 Key Click Filter