Every radio amateur should know about the basics of a radio transmitter, whether you are going to operate a commercial one or make one on your own, what we call by the pet name 'homebrew'. A radio transmitter is a device which generates a radiofrequency signal and sents it out as radio waves through the antenna. If only the radio frequency carrier wave is sent with breaks and makes corresponding to Morse Code formerly used in telegraphy, then it is known as a CW (Continuous Wave) transmitter, which is the simplest one. Like many other radio amateurs in the yester years, I had also homebrewed a basic CW transmitter using BD139 transistor as the final RF amplifier, running about 5W, known as QRP transmitter. Initial part of the transmitter is the radio frequency generator known as oscillator, which produces a high frequency oscillating current when you supply it with a direct current power supply. Oscillator section was called a VFO or Variable Frequency Oscillator as the frequency could be varied within the amateur radio band using a tuning circuit with a fixed value inductor and a variable capacitor. Single frequency crystal oscillators were also there, which had high stability as the frequency depended on the vibration of a quartz crystal which would be constant at a given temperature. Read More: https://johnsonstechworld.blogspot.com/2024/11/basics-of-radio-transmitter.html
