The basic components of a Southern Avionics®
Non-directional beacon (NDB) are the
Transmitter,
Antenna Tuning Unit (ATU) or
Antenna Coupler, and Antenna. The antenna consists of the radiator, insulators, and grounding system.
Customers may overlook the importance of correct antenna matching when using existing antennas with their new NDB & ATU. NDB antennas that have been in service many years often have deterioration or hidden damage in the radiator element, insulators, or the grounding system.
Because of the high voltages normally present, weakness in these areas can cause the antenna to short out. This will (correctly) cause the NDB transmitter to shutdown, or the antenna may simply have insufficient capacitance to allow optimal operation.