15th Edition
Low frequencies: Below 1MHz
The 136kHz band, 135.7kHz - 137.8kHz was introduced in January 1998 and is unique in being in the LF frequency range (Low Frequency, defined as 30kHz - 300kHz). It is available to holders of all classes of UK licence. In February 2007, the UK licensing authority Ofcom agreed to issue some amateurs with a “Notice of Variation†(NOV) to experiment on frequencies between 501 and 504kHz. Following internationally coordinated negotiations, this allocation was replaced by an internationally-agreed band from 472 to 479kHz which in the UK is available only to Full licensees. The 136kHz and 472kHz bands each have unique characteristics and are different to all the higher frequency amateur bands (for more on this, see the chapter on propagation). Due to the narrow bandwidth available at 136kHz (a total of only 2.1kHz), the low radiated power level permitted (1W ERP) and the high noise levels present on this band, digital modes like JT9 and FST4 are prevalent and CW activity has fallen. Some LF DX modes are described in detail in the Data Communications chapter. The 472kHz band has a slightly higher radiated power limit of 5W EIRP but it offers its own challenges, particularly the very deep fading that occurs at intermediate and long distances. There is still some CW operation on this band but digital modes are now the most popular.
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