The Basic lessons · Station assembly, practice and safety · B-003-011

CW Stability, AM Basics, and Transmitter Efficiency

Learn why steady power prevents frequency chirp in Morse code and how amplitude modulation creates sidebands. Understand where lost power goes in a transmitter and how to calculate bandwidth.

This lesson is part of SignalPrep Pro. The subsection's 11 exam questions are free to practise: practise B-003-011.

What this subsection asks

• What does chirp mean?
• What can be done to keep a CW transmitter from chirping?
• What is the advantage of using a variable frequency oscillator in a basic CW transmitter?
• Which type of transmitter modulation changes the amplitude of an RF wave for the purpose of conveying information?
• In what emission mode does the instantaneous amplitude (envelope) of the RF signal vary with the modulating audio?
• Morse code is usually transmitted by radio as:
• You are transmitting using amplitude modulation. What bandwidth does your signal occupy if the highest frequency of your voice is 3 kHz?
• What frequency components are present in the bandwidth of an amplitude modulated signal?
• An RF oscillator should be electrically and mechanically stable. This is to ensure that the oscillator does NOT:
• The DC power to the final stage of your transmitter is 200 watts and the RF output is 125 watts. What has happened to the rest of the power?
• The difference between DC input power and RF output power of a transmitter RF amplifier: