Radio Frequency Interference - Neas Letter See Also: Radio and Television Interference Noise The following is a portion of a letter Jeff sent to Mr. Earl Boswell, Thayer, when the Couch to Thayer 69 KV line was being planned. ___ In response to your letter of 4/24/96, we would like to address some of your concerns of possible RFI ( Radio Frequency Interference). The transmission line we are installing has an operating Voltage of 69,000 volts. The prediction of RFI is certainly not an exact science and unfortunately we don’t have any good technical literature on the subject. Typically, RFI is caused by bad Insulators, bad connections and Corona. The effects of corona are normally seen at higher voltages than 69,000 volts and are minimized by proper line design. The frequency of your Radio, the height and directional characteristics of your Antenna would play a large role in any interference problems. Sho-Me Power has an extensive Microwave(s) system covering all of south central Missouri. This system operates at 960 MHz and 2 GHz in and around high voltage substations and transmission lines. We also have two way radios in our vehicles that operate around 153 MHz. Interference has not been a problem for us. It has been very rare that others have called us concerning this type of problem. However, if you experience interference we want to help you resolve it.