History of tuning

The paper summarises many of the important developments that have taken place in the tuning of radio apparatus, starting with the early work of Oliver Lodge and Guigliemo Marconi. Over the years improvements have been made both to tuning capacitors and tuning coils. Amongst these were the development of air-spaced, vane-type capacitors and of magnetic cored materials for tuning coils, notably iron-dust and ferrites. Of special note was the introduction of variable capacitance semiconductor diodes, which made tuning possible by voltage control. The final part of the paper discusses a common method for the tuning of wide-band radio transmitters