A television receiver suffers interference on channel 5 (76 MHz - 82 MHz) only when you transmit on 14 MHz. From your home you see the tower of a commercial FM station known to broadcast on 92.5 MHz. Which of these solutions would you try first?

The problem described is a classic case of intermodulation occurring at the television receiver. The 92.5 MHz FM signal and your 14 MHz HF signal are mixing in the TV's front-end circuitry (92.5 MHz - 14.0 MHz = 78.5 MHz), which falls exactly into Channel 5's frequency range of 76 to 82 MHz. Because your transmitter is operating cleanly on its fundamental frequency of 14 MHz, putting a low-pass filter on your transmitter will not solve the issue. The interference is caused by fundamental overload at the TV. To resolve this, you must stop the 14 MHz signal from entering the TV in the first place. Inserting a high-pass filter at the television receiver will allow the higher-frequency TV signals to pass while blocking your lower-frequency 14 MHz HF signal.