Which filter would you use to prevent a HF transmitter from overflowing into harmonic frequencies?

To prevent a HF transmitter from overflowing into harmonic frequencies, a low pass filter is the most effective choice. A low pass filter allows signals below a certain cutoff frequency to pass through while attenuating frequencies above that threshold. In the context of a HF transmitter, this means that the fundamental operating frequency of the transmitter will be transmitted without significant loss, whereas any harmonic frequencies—typically those at multiples of the fundamental frequency—will be reduced or eliminated.

Harmonic frequencies can interfere with other communications and can violate regulations set by authorities, so effectively filtering them out is crucial for maintaining clear and compliant operations.

In contrast, a band pass filter is designed to allow a certain range of frequencies to pass while rejecting frequencies outside that range. This is useful for specific applications where only a narrow band of frequencies is desired, but not effective for preventing harmonic overflow across a broader frequency spectrum. A high pass filter allows higher frequencies to pass while attenuating lower frequencies, and would not limit the harmonics generated by the transmitter. A notch filter, on the other hand, is designed to reject a specific frequency while allowing others to pass, which would not comprehensively address the issue of harmonics across a broader spectrum. Thus, the low pass filter is the ideal solution for