What precaution must an amateur radio operator take when transmitting near band edges?

Radio transmissions do not occur on a single mathematically precise point; instead, they occupy a range of frequencies known as bandwidth. For example, a standard Single Sideband (SSB) voice transmission occupies about 3 kHz of frequency space. If you tune your radio's dial frequency exactly to the edge of an amateur band, part of your transmitted signal's bandwidth will spill over the edge and into frequencies allocated to other services. Operating outside of allocated amateur radio bands is a strict violation of regulations. Therefore, you must always ensure your dial frequency is set far enough away from the band edge so that your entire signal, including all of its sidebands, stays completely within the legal band limits.