Radio and Electronics Cookbook

25

The Colt 80 m receiver – Part 3

Introduction

In Part 2 we marked out the case ready for installation of the modules when they are completed. In this part, the building of the variable-frequency oscillator (VFO) and mixer will be described. This will produce a type of receiver known as direct-conversion, because it converts the radio-frequency (RF) signal directly into an audio-frequency (AF) signal which we can hear in a loudspeaker after amplification. A block diagram of the system is shown in Figure 1. The modifications needed to make a full superheterodyne receiver will be left until later.

Figure 1 Stages of direct-conversion receiver ...