Philips electron tube
Short history of the Philips electron tube (electronic valve).
This is the first Philips production type tube.
In 1918 delivered on order to the Nederlandse Radio-Industrie (owned by H.H.S. a Steringa Idzerda ). The model remained in production till 1922.
1923, types A110, A310
The emission improved considerably by replacing the bright emitter cathode by an oxide cathode. Because of the reduced filament current Philips introduced the trade mark 'Miniwatt'.
1927. Types B443, D143
In the Philips Research Laboratories ir. B.D.H. Tellegen developed in 1926 the five electrodes valve, called the pentode. The addition of the suppressor grid improved the operation of the tetrode considerably (gain and power). It was used in de final stage of the first Philips receivers 2501 and 2502 (1927).
1933. Type E446
The Pentode now also suitable for radio frequency amplification.
1934. Type AK1
This is a tube with 8 electrodes, designed for the mixing stage of the super heterodyne receiver.
For use in car radio the filament voltage was increased till 6.3 volt. The base has the contacts on the side.
1939. Type EF50
This is a high frequency pentode.
It is a special type of the loctal base tube with 9 pins. The construction has a base of pressed glass with short pins. This reduced the length of the internal wiring. So it became suitable for television and ultra shortwave reception.
At the beginning of the war parts and production facilities where moved from the Netherlands to England. It played an important role in military radar equipment.
This is the standard loctal base tube with 8 pins for use in commercial receivers.
Very compact receivers could be constructed with this tube, like the 203A 'Philetta' in 1941.
After the war came the Rimlock tube (r). This is a small glass tube with 8 pins and a locating pip on the side.
The Noval tube (l) has 9 asymmetrical positioned pins. In 1953 it was introduced as a NATO standard.