Load Coil

Load coils are also known as impedance matching transformers. Load coils are used by the telephone companies on long analog POTS (Plain Old Telephone Service) lines to filter out frequencies above 4 kHz, using the energy of the higher frequency elements of the signal to improve the quality of the lower frequencies in the 4 kHz voice range. Load coils are great for analog voice grade local loops, but must be removed for digital circuits to function. Load coils must be removed for DSL loops, as the frequencies required are well above 4 kHz. Today many phone companies offer broadband service, but often tell their customers that they can't get the service because "you live too far from the telephone company's office." Tell the company to remove the loading coils and any bridging taps on your local loop and it will work. Or offer to pay for commercial ADSL service. (We'll explore the flavors of DSL in future WotDs.)