845 (vacuum tube)
Encyclopedia
Triode
A triode is an electronic amplification device having three active electrodes. The term most commonly applies to a vacuum tube with three elements: the filament or cathode, the grid, and the plate or anode. The triode vacuum tube was the first electronic amplification device...
is a radio
Radio frequency
Radio frequency is a rate of oscillation in the range of about 3 kHz to 300 GHz, which corresponds to the frequency of radio waves, and the alternating currents which carry radio signals...
transmitting
Transmitter
In electronics and telecommunications a transmitter or radio transmitter is an electronic device which, with the aid of an antenna, produces radio waves. The transmitter itself generates a radio frequency alternating current, which is applied to the antenna. When excited by this alternating...
vacuum tube
Vacuum tube
In electronics, a vacuum tube, electron tube , or thermionic valve , reduced to simply "tube" or "valve" in everyday parlance, is a device that relies on the flow of electric current through a vacuum...
which can also be used as an audio amplifier
Valve audio amplifier
A valve audio amplifier or vacuum tube audio amplifier is a valve amplifier used for sound reinforcement, sound recording and reproduction....
and modulation
Modulation
In electronics and telecommunications, modulation is the process of varying one or more properties of a high-frequency periodic waveform, called the carrier signal, with a modulating signal which typically contains information to be transmitted...
tube. Typically, the plate
Plate electrode
A plate is a type of electrode that formed part of a vacuum tube. The plate is impressed with a positive charge so that it may capture and flow electrons within a circuit....
is machined from solid graphite
Graphite
The mineral graphite is one of the allotropes of carbon. It was named by Abraham Gottlob Werner in 1789 from the Ancient Greek γράφω , "to draw/write", for its use in pencils, where it is commonly called lead . Unlike diamond , graphite is an electrical conductor, a semimetal...
in order to accommodate high current
Electric current
Electric current is a flow of electric charge through a medium.This charge is typically carried by moving electrons in a conductor such as wire...
dissipation
Dissipation
In physics, dissipation embodies the concept of a dynamical system where important mechanical models, such as waves or oscillations, lose energy over time, typically from friction or turbulence. The lost energy converts into heat, which raises the temperature of the system. Such systems are called...
(up to 100 watt
Watt
The watt is a derived unit of power in the International System of Units , named after the Scottish engineer James Watt . The unit, defined as one joule per second, measures the rate of energy conversion.-Definition:...
s) and voltage
Voltage
Voltage, otherwise known as electrical potential difference or electric tension is the difference in electric potential between two points — or the difference in electric potential energy per unit charge between two points...
. Some current production 845 tubes have metal plates.
The 845 tube has a bayonet mount
Bayonet mount
A bayonet mount or bayonet connector is a fastening mechanism consisting of a male side with one or more pins, and a female receptor with matching L slots and spring to keep the two parts locked together....
and thoriated
Thorium dioxide
Thorium dioxide , also called thorium oxide is a white, crystalline powder. It was formerly known as thoria or thorina. It is produced mainly as a by-product of lanthanide and uranium production.[1]...
filaments which glow like lightbulbs when powered up. The glass envelope is about 2-5/16" in diameter and 6 inches tall, with the a total tube height of about 7-7/8 inches. It was first released by RCA
RCA
RCA Corporation, founded as the Radio Corporation of America, was an American electronics company in existence from 1919 to 1986. The RCA trademark is currently owned by the French conglomerate Technicolor SA through RCA Trademark Management S.A., a company owned by Technicolor...
in 1931. It saw extensive use in RCA AM radio transmitters