AmateurRadio.com

In the classic educational film titled “Electronics at Work,” produced by Westinghouse in 1943, viewers are introduced to the fascinating world of vacuum tubes. This film highlights the crucial role these devices played in both military and commercial sectors, including radio telecommunications, radar, and various industrial applications. The narrative suggests that vacuum tubes provided the United States with a significant advantage during World War II, particularly in enhancing communication and technology.

The Continuing Relevance of Vacuum Tubes

Despite advances in technology, vacuum tubes remain in use today for several applications, including:

– Transmitting radios
– Medical devices
– Audio amplification systems
– High-frequency applications

Understanding Vacuum Tubes

The film outlines the six basic functions of electronic tubes and illustrates how each type is employed in different industrial and military contexts.

Structure of a Vacuum Tube

A vacuum tube typically consists of two or more electrodes housed within a vacuum inside an airtight enclosure. Key features include:

– Electrode Types: Most vacuum tubes have glass envelopes, although some utilize ceramic or metal casings with insulating bases.

– Leads and Sockets: The electrodes connect to leads that pass through the envelope via an airtight seal. These leads often take the form of pins, allowing for easy replacement in a tube socket, as tubes were a common point of failure in electronic devices.

– Capacitive Design: Some tubes feature a top cap on the electrode to minimize interelectrode capacitance, enhancing high-frequency performance and maintaining safety by separating high voltages.

The Evolution of Vacuum Tubes

The earliest vacuum tubes emerged from incandescent light bulbs, which contained a heated filament sealed in an evacuated glass envelope. When heated, the filament releases electrons into the vacuum through a process known as thermionic emission.

– Electrode Functionality: A second electrode, known as the anode or plate, attracts these electrons if it holds a more positive voltage. This mechanism results in a flow of electrons from the filament (cathode) to the plate, creating an electric field due to the potential difference between them.

– Diode Function: A vacuum tube with two electrodes is termed a diode, which functions as a rectifier. Diodes allow current to flow in only one direction, converting alternating current (AC) into pulsating direct current (DC). This technology is widely used in DC power supplies and in demodulating amplitude-modulated (AM) radio signals.

Film Availability and Production Details

This film is available in the public domain under Creative Commons, and it can be accessed through the Library of Congress Prelinger Archives. The film has been edited and converted to HD quality for better viewing. Introductory and closing music is provided by Nero 10, with commercial use rights granted.

This film not only serves as an educational tool but also highlights the enduring legacy of vacuum tube technology in the realm of electronics, illustrating its significant contributions to both past and present technological advancements.

Please subscribe to my YouTube Channel: https://YouTube.com/NW7US

Also, please click on the bell, to enable alerts so that when I post a new video, you will be notified. By subscribing and making sure that the bell (alert) notification is set to ALL, you will be kept in the loop for new videos and more.

Introduction:

• It’s Second Spring in Texas, and Autumn is beginning in Arkansas, so sit back and enjoy another exciting episode of LHS.

Announcements:

• Paid subscribers to LHS may have noticed the web site certificate had expired. That problem is fixed.
• Welcome new subscribers Michael S., Michael C., and Bill A. Thank you!
• Sign-up for the LHS mailing list.
• Our LHS Ambassador to Ohio LinuxFest will be Scott, N8VSI. Thanks, Scott, and we look forward to hearing all about it.
• Please donate to the podcast and click on the affiliate links on the website.

Topics:

• HF Antennas, Horizontal vs. Vertical
  • Tonight, our hosts discuss the pros and cons of horizontally and vertically polarized HF antennas.
  • One thought is that once the RF radiation hits the various layers in the ionosphere, the polarization doesn’t really matter much as it gets reflected to and fro.
  • Richard offers the practical reason for preferring horizontal antennas for HF: it’s easier to build and erect the long antennas necessary for these frequencies. However, for chasing DX, those long-distance contacts, many hams prefer vertical antennas as they tend to have lower angles of radiation.
  • Also mentioned: GAP antennas and the G5RV antenna.
  • Wire horizontal dipoles are inexpensive and easy to construct. Verticals are a good choice when space is limited and can have a lower take-off angle, providing a good ground radial system is installed beneath them.
  • Horizontal antennas can be more directional. A dipole wire running north and south will have a better propagation east and west. A vertical is omnidirectional, radiating equally in all directions. To complicate matters, a horizontal antenna lower to the ground will radiate at higher angles than the same antenna that is higher. This can be useful for communicating with stations that are close to you.
• A new section of the podcast: Russ’ Rant!
  • Russ has a Yaesu FT-7900R, a dual-band UHV/VHF mobile radio. It has a removable front panel, allowing the main part of the radio to be hidden and the display can be easily mounted on the dash. However, the speaker is on the body of the radio, so you can’t hear it if it’s hidden under the seat or in the trunk! Russ thinks the head unit should also contain a speaker, perhaps a very small one like in an mp3 player. Or put the speaker in the microphone.
• Returning to antennas, Richard recommends that KD8SZG (in the chat room), should try building his own wire antennas for HF. Any of the antenna books written by Doug DeMaw, W1FB, are good resources. His Antenna Notebook is one. (I also like the various ARRL antenna books, like the Simple and Fun Antennas for Hams. -Ed.)

Contact Info:

• Contact Richard at [email protected], Russ at [email protected], or both at the same time at [email protected].
• Listen to the live stream every other Tuesday at 8:00pm Central time. Check the LHS web site for dates.
• Leave us a voice mail at 1-909-LHS-SHOW (1-909-547-7469), or record an introduction to the podcast.
• Sign up for the LHS mailing list.
• Sign up for the MAGNetcon mailing list.
• LHS merchandise is available at the Merch link on Web site. Check out the Badgerwear or buy one of the other LHS-branded items at PrintFection.com/lhs or Cafe Press. Thanks!
• Thanks to Dave from Gamma Leonis for the theme music.

Music:

• “A Little Time” by Not From Georgia, from their album Love & Umbrella, courtesy of Jamendo.
• “Metal Heart” by Zamza, from their album Songs for Jukebox, courtesy of Jamendo.