ARRL Technician Practice Exam 2026 – 400 Free Practice Questions to Pass the Exam

The approximate maximum bandwidth required to transmit a Continuous Wave (CW) signal is around 150 Hz. This bandwidth is determined by the nature of CW modulation, which involves transmitting a signal at a constant frequency that is turned on and off to encode information, usually in Morse code.

CW signals are unique in that they have a very narrow bandwidth compared to other modes of transmission. When a CW signal is transmitted, the frequency is stable, and the information is conveyed through the duration and spacing of the on/off keying. As a result, the bandwidth does not need to be excessively wide; 150 Hz is generally sufficient to accommodate the signal’s keying transitions and ensure clear reception without interference.

This bandwidth allows for adequate time for the signal to rise and fall during transmission, ensuring the integrity of the Morse code characters while still maintaining a minimal frequency range to reduce the chance of interference with adjacent signals. Other modes of transmission, such as voice or digital modes, utilize wider bandwidths due to their more complex modulation processes.