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Subelement B-004

B-004

Section B-004-005

Section B-004-005

What is one reason a triode vacuum tube might be used instead of a transistor in a circuit?

  • It is much smaller
  • It uses less current
  • It uses lower voltages
  • Correct Answer
    It may be able to handle higher power

Vacuum triodes are larger, use current just to heat the filament and require higher voltages than transistors BUT they remain simpler to use in HIGH-POWER amplifiers.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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Which two elements of a triode carry the output current?

  • Correct Answer
    Cathode and plate
  • Source and drain
  • Cathode and grid
  • Emitter and collector

The triode has three elements: a control grid, a cathode and a plate (or anode). The current between cathode and plate is what the control grid can affect.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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A feature common to triode tubes and transistors is that both:

  • Correct Answer
    can amplify signals
  • dissipate heat when not conducting
  • use heat to cause electron movement
  • have electrons drifting through a vacuum

Only vacuum tubes use heat to facilitate electron movement within an envelope free of air.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

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Which electrode on a vacuum tube is operated with the highest positive voltage?

  • Grid
  • Correct Answer
    Plate
  • Cathode
  • Collector

The 'Plate' (or Anode) attracts electrons with a high positive voltage. The Cathode emits electrons. The Grid encircles the Cathode and controls the flow of electrons.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

Which semiconductor device has characteristics most similar to a triode vacuum tube?

  • Thyristor
  • Bipolar transistor
  • Correct Answer
    Field-effect transistor
  • Triac

The field-effect transistor and the triode both use a reverse voltage on their control electrode to affect current through the device.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

Which electrode of a vacuum triode is the control element?

  • Correct Answer
    Grid
  • Emitter
  • Plate
  • Cathode

The 'Plate' (or Anode) attracts electrons with a high positive voltage. The Cathode emits electrons. The Grid encircles the Cathode and controls the flow of electrons.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

In a vacuum tube, which electrode emits electrons?

  • Collector
  • Grid
  • Correct Answer
    Cathode
  • Plate

The 'Plate' (or Anode) attracts electrons with a high positive voltage. The Cathode emits electrons. The Grid encircles the Cathode and controls the flow of electrons.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

What is inside the envelope of a triode tube?

  • Correct Answer
    A vacuum
  • Neon
  • Argon
  • Air

A 'vacuum' is the absence of air. Air is pumped out of vacuum tubes (like light bulbs) to prevent the filament from burning up.

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

What term describes a vacuum tube with a cathode, a single grid and a plate?

  • Correct Answer
    Triode
  • Tetrode
  • Diode
  • Pentode

The prefix "tri" inherited from Latin and Greek means "three". A triode is a 3-electrode device: a cathode, a control grid and a plate (or anode).

Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.

Tags: none

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