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The cathode of the power pentode is designed to be capable of sufficient electron emission to give the required current through the tube to produce the desired power in the load impedance. [13] The plate or anode of a power pentode is designed to be capable of dissipating more power than that of an ordinary pentode. [14]
Schematic symbol used in circuit diagrams for a vacuum tube, showing control grid. The control grid is an electrode used in amplifying thermionic valves (vacuum tubes) such as the triode, tetrode and pentode, used to control the flow of electrons from the cathode to the anode (plate) electrode. The control grid usually consists of a cylindrical ...
The design produced more output power than a similar power pentode. [4] The transconductance was higher than a similar power pentode. [14] The plate resistance was lower than a similar power pentode. [14] The screen grid current was about 5–10% of the anode current compared with about 20% for the pentode, thus the beam tetrode was more power ...
The space charge grid tube was the first type of tetrode to appear. In the course of his research into the action of the audion triode tube invented by Edwin Howard Armstrong and Lee de Forest, Irving Langmuir found that the action of the heated thermionic cathode was to create a space charge, or cloud of electrons, around the cathode.
The EF86 [1] is a high transconductance sharp cutoff pentode vacuum tube with Noval (B9A) base for audio-frequency applications. It was introduced by the Mullard company in 1953 [2] and was produced by Philips, Mullard, Telefunken, Valvo, and GEC among others. It is very similar electrically to the octal base EF37A and the Rimlock base EF40.
This is a list of vacuum tubes or thermionic valves, and low-pressure gas-filled tubes, or discharge tubes. Before the advent of semiconductor devices, thousands of tube types were used in consumer electronics.
Examples of this format are "PL302" and "EF183". From about the start of the 1960s an extra digit was needed for new devices. Either a digit 1 was inserted before the 8 or other base-defining digit (e.g. an EF184 is a Noval pentode), or a three-digit sequence was used. For example, a PL500 is a power pentode in a Magnoval base.
The vacuum state of the "free" electromagnetic field (that with no sources) is defined as the ground state in which n kλ = 0 for all modes (k, λ). The vacuum state, like all stationary states of the field, is an eigenstate of the Hamiltonian but not the electric and magnetic field operators.