The first experiments in the History of the Radio, were made with spark transmitters ("TeleSpark").
In a brief history of Radio: The German scientist Hertz produced Radiofrequency, using an spark gap and their "Hertz Ressonator".
Nikola Tesla made their coils, an better source for sparks (Based on an improvement over the old Rumkorff Coils), but is was interested in produce energy, not in communication.
In Brasil Landell de Moura worked with radio devices transmitting Voice (prior to Marconi!) but Marconi received the Nobel Prize as Radio Inventor, because he carried out this for really, worldwide communication purposes., but He transmitted only telegraphy, and Landell de Moura, voice. Another Landell de Moura Link.
Despite, Marconi not developed really new devices, since He used the Hertz ressonator, the Tesla Coil and the coherer or galena detectors, previously know devices. But He was processed and said not to know previous Tesla inventions!
After, In England, Lee de Forest also generated Radiofrequency, but for the purpose to test their Electron Tube, an invention extensive aplied in Radio. In this manner Landel de Moura and Marconi, may be considered really the pioners of Radio. Site about Landell de Moura,
Links about Tesla Coils and Kirlian Photography Equipment: Tesla's Legacy; KirlianLab, Make an Tesla Coil(Portoguese); Tesla Mind (Portoguese). High Voltage Power Supplies, Making Super high voltage power supplies (Portoguese); Steve's High Voltage Page.
Interesting Radio and Electronics Links:
BRAZILIAN AND OTHER COUNTRIES ELECTRONICS MAGAZINES:
The Magazine Antenna is the older Brazilian Electronics Magazine, exists since the Age of the Electron Tubes, in the Radio Begin ( 1926). In 1983, it incorporated other Magazine, Eletrônica Popular. The antique numbers and also the new, may be purchased in digital format. Here, aLink for many other Electronics Magazines. Circuits and Informations for Electronics and Hobbiysts, Assemblies etc... may be found in these links: A, B, C, D. E. F. G, H, I. Elecktor is a good Electronics Magazine (see with this Nixie Tube article)