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.

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Curious about what you can hear on shortwave ham radio? This video is a brief survey of the diverse world of communications on the shortwave spectrum. Expand your radio horizons and enhance your emergency communication preparedness by tuning in to the world of shortwave ham radio.

If you’ve started delving into radio communications beyond local stations and channels, like VHF and UHF, you’re in for a treat. Shortwave radio opens up a whole new realm of signals to explore, including emergency communications vital during natural disasters.

Shortwave radio covers a range of radio frequencies from 3 kHz to 30 MHz. This spectrum is home to a diverse array of radio signals that cater to various communication needs, making it a hub of activity and connectivity.

Within these high frequencies, you can tune in to a multitude of transmissions, from transoceanic air traffic control communications to the chatter of ships navigating the vast seas. Imagine hearing the voices of fishermen, much like those on your favorite reality TV shows about high-seas fishing adventures, along with military communications and the vibrant world of amateur radio enthusiasts.

One of the remarkable features of high-frequency (HF) radio is its ability to propagate signals over long distances, transcending line-of-sight limitations. This means that HF radio enables communication between different regions and even continents, fostering connectivity across vast distances.

During times of crisis and natural disasters, shortwave frequencies become invaluable for emergency communications. When local infrastructure falters or is disrupted, shortwave radio serves as a vital lifeline, facilitating critical two-way communications in and out of disaster-stricken areas.

Explore the fascinating realm of shortwave radio, where distant voices blend with essential information, bridging gaps and connecting communities in times of need. Uncover the power of HF radio to transcend boundaries and provide lifelines when they are needed most.

In this video, I give you a glimpse of the voice and data transmissions I pick up on my high-frequency amateur radio transceiver (in this video, an Icom IC-7000). In later videos, I will dive deeper into specific types of HF communications, such as aeronautical trans-oceanic signals.

The Colorado Search and Rescue Association is promoting FRS (Family Radio Service) Channel 3 as “the default during backcountry search and rescue (backcountry SAR) emergencies.” FRS channel 3 is the same as GMRS (General Mobile Radio Service) channel 3. There is more GMRS info here. To keep things simple, no CTCSS (“privacy code”) is used…carrier squelch only.  See the CSAR announcement here: FRS Radio Use for Backcountry.

For backcountry exploring, it is important to emphasize self-sufficiency and to avoid reliance on electronic gizmos that may fail. Avoiding an emergency situation is way better than having a device to call for help, which may be many hours away. See this article for a discussion of The Ten Essentials for Hiking.

Still, the FRS3 concept has merit. Many backcountry hikers already carry FRS or GMRS radios, so designating a preferred channel makes sense. My read on this is that randomly calling for help on FRS3 will not be very effective due to the limited range of FRS radios. However, it does not hurt to try. More likely, FRS3 can be used for local comms once Search and Rescue crews have been deployed and are within a few miles of the party in distress.

Ham radio operators may want to carry a handheld transceiver capable of transmitting on 462.6125 MHz. For emergency use only, of course.

73 Bob K0NR

The post FRS3 For Colorado Backcountry appeared first on The KØNR Radio Site.

There is a new book from a fellow Morse code amateur radio operator, Chris Rutkowski (NW6V), about “Learning, Living, and Loving Morse Code (in a Digital World).” NICE!

Title: “The CW Way of Life“
link: https://amzn.to/3Tm3KfD

I received a new book! Here it is, at my radio shack operations desk, at NW7US radio station.

Already, I think it rivals any other book on the topic, including “The Art and Skill of…,” or, “The Zen of…”

It is not, however, meant to replace, but to augment, what is available. But, it is a complete guide, including a “work book” section (nearly half of the book?) on how to improve your skill. Really good stuff, but I’m only in one day.

73 de NW7US dit dit
https://nw7us.us

..

Some folks are criticizing the ARRL for not modifying the Field Day rules in response to the Wuhan virus epidemic. Most of them are looking for a way to operate Field Day from home but still have a club score of some kind. I posted my thoughts here: Don’t Mess With The Field Day Rules.

The Field Day (FD) rules allow for a home station with commercial power to participate in FD as a Class D station. However, Class D stations cannot work other Class D stations for points. If the home station has emergency power (batteries, gasoline generator, etc.), then it is a Class E station that can work all FD stations for point credit.

Emergency Power: Too Difficult?

I’ve heard some hams argue that it is too difficult to set up emergency power for their home station. In many cases, the argument is actually that it is too expensive to do this.  I can see this point if you run out and buy a name brand gasoline generator…a Honda EU1000i costs about $950.

This raises the question of what is the lowest-cost way to equip a home station for emergency power?  Let’s consider the case of a typical 100W HF transceiver such as an IC-7300 or FT-991A. These radios require a 12 V power supply at 22 A maximum on transmit. Receive current is much lower, typically 1 to 2 A. Under FD rules, we don’t need to power our computer or other accessories from emergency power, just the radio. If we assume a 50% duty cycle, this class of radio consumes about (22+2)/2 = 12 A average current. (Yes, you could choose to operate QRP and really stretch the battery but let’s stay with the 100 W scenario.)

Get A Battery

So what is the cheapest way to get this done? Let’s take a look at using a deep-cycle battery. Walmart has an RV/Marine battery for $75, rated at 101 AH. Assuming 12 A of current, this battery would support about 8 hours of radio operating. This is going to be way short of the 24 hour operating period of FD but it might be enough to support a less intense operation.  We could also do some things to stretch out the battery life, such as reducing our transmit power. Dropping to 50 W would roughly double the operating time to 16 hours, which should be enough for a single-operator station.

Of course, another option is to double the battery capacity by using two batteries. These amp-hour ratings on batteries are always a bit idealistic and our transmit duty cycle might be more than 50%. Let’s assume we buy two batteries to give extra margin and allow us to run 100W. We will also need a simple charger, which costs about $25. So there you have it, 2 x $75 plus $25 = $175 for a decent emergency power source.  (If we decide to use only one battery, the cost drops to $100.)

Now $175 is a significant investment and only you can judge how well your ham radio budget can support this. For many people, this is affordable and the real question becomes is this how you want to spend my hard-earned cash.

This is my best shot at a low-cost emergency power source. Do you have a better idea?

73 Bob K0NR

The post How Much Does Emergency Power Cost? appeared first on The KØNR Radio Site.

Given the Chinese/Wuhan/COVID virus situation, many hams are anticipating a change to their ARRL Field Day operation. I’ve also seen a number of proposals to modify the FD rules to allow for a different kind of operation. I appreciate that kind of thinking outside the box but I think it is misguided. One of the strengths of FD is it already has a set of flexible rules and operating classes, so you can adapt it to what you or your club wants it to be. See my post: ARRL Field Day – Season to Taste

Some Ideas

What are some of the proposals? The first one I noticed is a proposal to allow all Class D stations (home station with commercial power) to work other Class D stations for points. The FD rules do not currently allow this. Class E stations (home station with emergency power) are allowed to any class station. Obviously, this rule is to encourage people to develop emergency power capability (and use it) for their home station. This is perfectly aligned with the emcomm focus of Field Day.

Another proposal is to allow a “backyard operating” class, where you set up a portable station in your backyard. Of course, this is already allowed under the rules as a Class B station.

One of the more innovative ideas I’ve heard is to allow multiple stations (not colocated) to operate under one club callsign, coordinating their operation via the internet. This approach emulates a “normal” Class A FD operation, while everyone is locked down at home. This is not allowed as a Class A station:  “All equipment (including antennas) must lie within a circle whose diameter does not exceed 300 meters (1000 feet).”  This is roughly equivalent to a group of Class D or E stations working together towards a common score. Why not just operate as independent Class D and E stations, which is more like a real emergency situation?

Adapt and Innovate

Our local radio club is considering different ways to adapt, seeing this as a training and learning opportunity. We will probably encourage our members to get on the air individually, with emergency power. We will likely encourage members to work other members, providing some kind of incentive or award. So our FD may look more like a local operating event, in addition to working distant stations. VHF/UHF will probably play an important role so that we include Technician licensees. Not sure just yet.

We are all experiencing some serious challenges this year and Field Day is not going to be the same. I am a bit surprised that the first thought about Field Day is to change the rules to make it easier or somehow better. I think we just need to adapt and innovate within the existing format. Existing Field Day Rules have plenty of flexibility.

That’s what I say. What do you think?

73 Bob K0NR

The post Don’t Mess With The Field Day Rules appeared first on The KØNR Radio Site.