Which of the following might reduce interference by an amateur station to a non-amateur over-the-air radio receiver?

When a clean, properly operating amateur transmitter causes interference to a nearby non-amateur receiver (like a consumer TV or stereo), the issue is usually 'fundamental overload.' The amateur's fundamental signal is simply too strong for the consumer receiver's front end to handle, causing it to become overwhelmed. The most effective way to solve fundamental overload is to install a filter directly at the antenna input of the affected consumer receiver. This filter (such as a high-pass or notch filter) will block the amateur frequency from entering the device while allowing the desired broadcast signals to pass through. Putting a filter on the amateur transmitter will not solve this problem, because transmitter filters only suppress harmonics and spurious emissions; they do not block the fundamental frequency that is causing the overload. Changing transmission modes also will not prevent a strong RF field from overloading a poorly shielded nearby receiver.