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RMA Tube Designation
In the years 1942-1944, the Radio Manufacturers Association used a descriptive nomenclature system for industrial, transmitting, and special-purpose vacuum tubes. The numbering scheme was distinct from both the numbering schemes used for standard receiving tubes, and the existing transmitting tube numbering systems used previously, such as the "800 series" numbers originated by RCA and adopted by many others. The system assigned numbers with the base form "1A21", and this numbering scheme is occasionally referred to by tube collectors and historians as the "1A21 system". The first digit of the type number was 1-9, providing a rough indication of the filament/heater power rating (and therefore the overall power handling capabilities) of the tube. The assigned numbers were as follows: *1-- No filament/heater, or cold cathode device *2-- Up to 10 W *3-- 10-20 W *4-- 20-50 W *5-- 50-100 W *6-- 100-200 W *7-- 200-500 W *8-- 500W-1 kW *9-- More than 1 kW The second character w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vacuum Tubes
A vacuum tube, electron tube, valve (British usage), or tube (North America), is a device that controls electric current flow in a high vacuum between electrodes to which an electric potential difference has been applied. The type known as a thermionic tube or thermionic valve utilizes thermionic emission of electrons from a hot cathode for fundamental electronic functions such as signal amplification and current rectification. Non-thermionic types such as a vacuum phototube, however, achieve electron emission through the photoelectric effect, and are used for such purposes as the detection of light intensities. In both types, the electrons are accelerated from the cathode to the anode by the electric field in the tube. The simplest vacuum tube, the diode (i.e. Fleming valve), invented in 1904 by John Ambrose Fleming, contains only a heated electron-emitting cathode and an anode. Electrons can only flow in one direction through the device—from the cathode to the anode. A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
