Where must a filter be installed to reduce harmonic emissions?

To effectively reduce harmonic emissions, the filter should be installed between the transmitter and the antenna. This location is optimal because it directly addresses the potential for unwanted harmonics generated by the transmitter. When a radio frequency signal is transmitted, it may produce multiple frequencies, including harmonics that can interfere with other communications and cause compliance issues with regulations.

By placing the filter at this point in the setup, only the desired frequency is transmitted, while the filter attenuates or blocks these unwanted harmonics before they can radiate out through the antenna. This positioning helps ensure that your transmissions are cleaner, meet regulatory standards, and reduce interference with nearby electronic devices and other radio services.

While filters can be useful in various locations within a station, the main goal of preventing harmonic radiation aligns most closely with their placement between the transmitter and the antenna. This choice is critical for maintaining the integrity of the transmission and contributing to responsible amateur radio operation.