Initially, radio transmissions were broadcast on frequencies ranging from 100kHz to 1500kHz (ie, on wavelengths from 3000 metres to 200 metres, respectively). However, there were some high-power transmissions below 100kHz.

This view of the AWA C103/43 converter shows the layout on the top of the chassis. All parts are readily accessible, making it easy to service.

Basically, all "important" transmissions were licensed or permitted to operate in this general frequency range. By contrast, those "pesky" experimenters and amateurs were permitted to use any of the so-called "useless" frequencies above 1500kHz. Because of this frequency allocation, they were not expected to be able to contact each other over long distances but they quickly proved the authorities wrong!

Radio transmissions for entertainment commenced during the early 1920s and quickly became popular. As a result, radio manufacturers and home constructors developed receivers to operate on both the long-wave and medium-wave bands (100-1500kHz). At the time, there was no reason to have radios capable of tuning above 1500kHz, since those frequencies were used only by the experimenters.

In any case, the components used in radios at the time were generally unsuitable for frequencies above 1500kHz, as was the layout of the sets. That didn’t deter the experimenters, however. They immediately set about making the most of the frequencies that they were permitted to use and began by experimenting with ways to improve both the stability and the performance of their receivers and transmitters.