He then settled in
Scheveningen in the Ten Hovestraat as an independent consultant "for the application of electricity in every field". He probably first registered at his branch in The Hague in June 1913 under his first names Hanso Henricus and the surname Schotanus à Steringa Idzerda. The first names Schotanus à Steringa were therefore included in the surname. Between 1907 and 1917 he worked on further developing the
triode vacuum tube that had already been invented in America in 1906 by
Lee De Forest. The
Eindhoven light bulb factory of
Philips took the tube into production in 1918 under the name PH-IDZ (Philips Ideezet). The tube had a limitation, because it was only suitable for transmitting
Morse code. It was not yet possible to transmit sound. To achieve this, transmitting triode tubes with greater frequency range and a greater power were required. Together with Philips, Idzerda developed several improved test models. Idzerda focused on the development of radio transmitting and receiving equipment. In his own company, under the name Technische Bureau Wireless, he started manufacturing equipment, which he supplied to the Dutch army, among others. During the First World War, he experimented at the
presbytery of his parents-in-law, the Nicolaï family in
Mantgum. With
radio direction finders he built himself, he was able to determine the location of radio transmitters, including those of German
zeppelins that sailed to England. The Dutch armed forces made grateful use of his information. During the
Utrecht Jaarbeurs, at the end of February 1919, he demonstrated radiotelephonic transmissions over a distance of 1200 meters for the first time in the Netherlands. The excitement among the audience was great and even the then
Queen Wilhelmina came to listen. On 6 November 1919 he held the first public airing of a
radio program. His program consisted of music, and him talking for a bit in between pieces. The
PCGG transmitter he invented was capable of transmitting signals from
The Hague all the way to
England.
Herman de Man, later to be an important author and radio maker, was present. From then on the program aired every week. In 1922 the
Daily Mail decided to sponsor Idzerda, who previously financed the operation with his own money and some donations. After the
Daily Mail ceased its support Idzerda's company went bankrupt. ==Execution==