Category Archives: Radio History

Radio Waves: Crossband Test Postponed, VI3RA Event Videos, WWII Radio, and Look Inside a Panasonic RF-4900

Radio Waves:  Stories Making Waves in the World of Radio

Because I keep my ear to the waves, as well as receive many tips from others who do the same, I find myself privy to radio-related stories that might interest SWLing Post readers.  To that end: Welcome to the SWLing Post’s Radio Waves, a collection of links to interesting stories making waves in the world of radio. Enjoy!

Many thanks to SWLing Post contributors Harald Kuhl, Michael Bird, and Carel Kuijer for the following tips:


Annual Armed Forces Day Crossband Test Postponed (ARRL News)

Due to the ongoing COVID-19 response and mitigation actions, the 2020 Armed Forces Day (AFD) Crossband Test scheduled for Saturday, May 9, has been postponed. Because it’s uncertain just when stay-at-home orders will be lifted across the US, AFD planners chose to postpone this year’s event, because the government stations that typically support this event may not be available. Armed Forces Day Crossband Test planners are considering scheduling a November event in honor of Veteran’s Day, depending on COVID-19 mitigation actions. During the AFD Crossband Test, military stations in various locations transmit on selected military frequencies and announce the specific ham frequencies they are monitoring to work radio amateurs. — Thanks to US Army MARS Program Chief Paul English, WD8DBY

Radio Australia Event – Antenna Overview (Mount Evelyn DX Report)

Thanks to Lee VK3GK for this short video of the antennas used for the recent Radio Australia event using the call sign VI3RA. Take what will possibly be a final look at the feeders, switching boxes and antennas before they are pulled down and junked!

Also here is the final transmission of the event weekend with, of course, the famous Radio Australia music box interval signal.

Click here to view both videos at the Mt Evelyn DX Report.

World War II and Radio (All Things Radio)

I have added an article I wrote some years back on the code breaking efforts of the Allies during WWII. While certainly not exhaustive, I found many of the connections between countries and equipment rather fascinating, and new things continue to pop up regarding Bletchley Park’s role in training officers and decoding texts. While most famously known for breaking the Enigma code, also significant was the breaking of the Lorenz Cipher.

Click Here to download the article in PDF format.

73, Robert K4PKM

Look Inside This Radio Receiver! The Collectible Panasonic RF 4900 (Mr. Carlson’s Lab – YouTube)

Let’s look inside this Panasonic RF-4900 radio receiver, and see what we have to restore.


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Radio Waves: New FCC RF Exposure Limits, Rediscovering Spark Gap, Zoom Vulnerabilities, and Extremely Rare Film of MI6 Section VIII

Radio Waves:  Stories Making Waves in the World of Radio

Because I keep my ear to the waves, as well as receive many tips from others who do the same, I find myself privy to radio-related stories that might interest SWLing Post readers.  To that end: Welcome to the SWLing Post’s Radio Waves, a collection of links to interesting stories making waves in the world of radio. Enjoy!

Many thanks to SWLing Post contributors Paul Evans, and Robert Gulley for the following tips:


FCC Publishes new RF exposure rules (Federal Register)

The FCC has published the new rules in the Federal Register.

Paul notes:

Different above 6GHz
Expanding rules from 3 kHz – 300 GHz to 3 kHz – 3 THz (inc. light
frequency RF sources, essentially future proofing rules)
Introducing SAR measurements from 100 kHz to 6 GHz (impact to ARS)
Introducing MPE measurements above 6 GHz
Introducing ideas for WPT at and below 100 kHz, with control over the
wires or remotely over the air. This is (obviously) for EV charging.
They say nothing about harmonics, filtering, etc.[]

We Rediscover Spark Gap Radio by Accident (CuriousMarc via YouTube)

It’s 1890 all over again in the lab. By complete accident, I find myself the new owner of a high voltage box that turns out to be a vintage Xenon lamp sparker. Not only do we make it work, but we use it to retrace the critical experiments that led to the discovery of radio, using the lamp starter as the spark gap transmitter, and a coherer as the receiver.[..]

Click here to view on YouTube.

Zoom taking your club online – DON’T (Southgate ARC)

On Friday 3rd April, we carried an item regarding the use of Zoom for club meetings.

However, we have since been contacted by Paul, VP9KF, who offers this note of caution.

He says:
“This story http://www.southgatearc.org/news/2020/april/zoom-taking-your-radio-club-online.htm on your page recently is over-shadowed by the news as follows:

https://www.theguardian.com/technology/2020/apr/02/zoom-technology-security-coronavirus-video-conferencing

Don’t use Zoom and get hacked ”

Our thanks to Paul for this informative, if not rather worrying, news item.

[Paul notes that Skype Conference Call is the best method because it is “secure, end to end. In browser (sandbox) with HTML5 embedded features.”]

WW2 Codebreakers: Bletchley Park activities revealed in unique footage – The Hidden Film (YouTube)

Discover the story behind the recently discovered only known wartime film footage of a secret site connected to Bletchley Park.

A silent film, recently donated to Bletchley Park Trust, is believed to be a compilation of footage recorded between 1939 – 1945, showing members of MI6 Section VIII at Whaddon Hall, Buckinghamshire. During World War Two, this was a most secret site where Ultra intelligence produced by the Government Code and Cypher School (GC&CS) at Bletchley Park would be sent, and then passed on to Allied commanders in the field.

In this mini-documentary, hear Bletchley Park Veteran, Geoffery Pidgeon who worked in MI6 Section VIII during WW2, recall how it felt to watch the film for the first time and recognise his father. Peronel Craddock, Bletchley Park’s Head of Collections and Exhibitions and Dr. David Kenyon, Research Historian at Bletchley Park also talk about why the discovery of this film is so important.

Watch the original footage: https://youtu.be/bvVaFE5O3eY


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Radio Waves: The Future of On-Air DJs, SDR Comparison, Radios That Never Were, and an Internet Radio Player for Linux

Radio Waves:  Stories Making Waves in the World of Radio

Because I keep my ear to the waves, as well as receive many tips from others who do the same, I find myself privy to radio-related stories that might interest SWLing Post readers.  To that end: Welcome to the SWLing Post’s Radio Waves, a collection of links to interesting stories making waves in the world of radio. Enjoy!

Many thanks to SWLing Post contributors Jack Kratoville, Dave Zantow, and Dennis Dura for the following tips:


Live From Everywhere? The American Radio DJ In An On-Demand World (1A)

iHeartMedia owns and operates 858 broadcast radio stations, serving more than 150 markets throughout the U.S. The company reaches over a quarter billion monthly listeners ?in America.

In January, news hit that iHeartMedia was reassessing its ability to adapt to the modern music industry. The company said that it plans to make “significant investments … in technology and artificial intelligence.”

However, its on-air DJs were caught off guard when they found out that the company’s restructuring plan didn’t include them.

Streaming platforms has ushered in the digital age of music where each person make their own playlists. What does that mean for the future of the on-air DJ in the United States?

Click here to listen to the audio.

A comprehensive lab comparison between multiple software defined radios (RTL-SDR.com)

Librespace, who are the people behind the open hardware/source SatNOGS satellite ground station project have recently released a comprehensive paper (pdf) that compares multiple software defined radios available on the market in a realistic laboratory based signal environment. The testing was performed by Alexandru Csete (@csete) who is the programmer behind GQRX and Gpredict and Sheila Christiansen (@astro_sheila) who is a Space Systems Engineer at Alexandru’s company AC Satcom. Their goal was to evaluate multiple SDRs for use in SatNOGS ground stations and other satellite receiving applications.

The SDRs tested include the RTL-SDR Blog V3, Airspy Mini, SDRplay RSPduo, LimeSDR Mini, BladeRF 2.0 Micro, Ettus USRP B210 and the PlutoSDR. In their tests they measure the noise figure, dynamic range, RX/TX spectral purity, TX power output and transmitter modulation error ratio of each SDR in various satellite bands from VHF to C-band.

The paper is an excellent read, however the results are summarized below. In terms of noise figure, the SDRplay RSPduo with it’s built in LNA performed the best, with all other SDRs apart from the LimeSDR being similar. The LimeSDR had the worst noise figure by a large margin.[]

Radios that Never Were (N9EWO)

Dave Zantow (N9EWO) shares a new page on his website devoted to receivers and amateur transceivers that never quite made it to the marketplace. []

Shortwave: A Modern Internet Radio Player for Linux (It’s Floss)

Brief: Shortwave is a modern looking open source Internet Radio player for Linux desktop. We take a quick look at it after its recent stable release.

Shortwave is an interesting open-source radio player that offers a good-looking user interface along with a great experience listening to the Internet stations. It utilizes a community-powered database for the Internet stations it lists.

Shortwave is actually a successor of the popular radio app for Linux, Gradio. Its developer Felix joined GNOME and discontinued Gradio to create Shortwave from scratch in Rust programming language. If you were using Gradio as your preferred Internet radio station player, you can import the library as well.

Recently, Shortwave released its first stable version and seems to push new updates after that as well.[]


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Radio Waves: ACMA Report, Maine Stations Close, The National Emergency Library, and RAF Bombing Disrupted Propaganda

Radio Waves:  Stories Making Waves in the World of Radio

Because I keep my ear to the waves, as well as receive many tips from others who do the same, I find myself privy to radio-related stories that might interest SWLing Post readers.  To that end: Welcome to the SWLing Post’sRadio Waves, a collection of links to interesting stories making waves in the world of radio. Enjoy!

Many thanks to SWLing Post contributors Alan, Bill Mead, Bill Hemphill, and Gregg Freeby for the following tips:


The future delivery of radio (Australia Communications and Media Authority)

The ACMA released an issue paper in May 2019 to hear from industry about the delivery of radio.  We also wanted to consider if there needs to be any changes to support radio services into the future.

Following this, we conducted a public consultation, receiving submissions from across the industry. We found that live radio across different platforms is important to Australians. This is especially relevant during emergency situations, such as the recent bushfires. We also determined that a mix of platforms is crucial to bringing radio to listeners.

Our report identifies four broadcast spectrum planning priority activities to help support radio:

    • converting commercial, community and national radio broadcasting services from AM to FM where available
    • improving the coverage of radio broadcasting services where spectrum is readily available
    • making digital radio channel plans for regional DAB+ where there is a planned rollout
    • supporting trials of new broadcasting technology.

Report to the Minister Future delivery of radio (319.59 KB)

WOXO says farewell to listeners; Gleason Radio Group to go silent after 45 years (Sun Journal)

AUBURN — On Maine Big Z’s “The Breakfast Club,” Mark Turcotte interviewed local business owners, entertainers, activists, and once last summer, a mixed martial arts cage fighter and state senator one hour apart.

“Had to shift gears pretty quickly that morning,” quipped Turcotte, the morning show host since December 2018.

On Wednesday, he was abruptly down to two final shows.

Gleason Radio Group announced that its five stations will go off the air at 7 p.m. Sunday. They include Norway, Paris, Rumford, Mexico and Auburn.

“This feels like the end of an era in Maine radio,” Turcotte said.

Kathy Gleason has run the business with WOXO station manager Vic Hodgkins in the year since her husband, founder and former Auburn Mayor Dick Gleason, died.

“I feel that I tried very hard to keep it going and at the same time have it be for sale,” Gleason said. “It didn’t sell, it may sell. The coronavirus was kind of like the last straw as far as finances go.”

Hodgkins said a combination of low receivables and slow payments, combined with a projected drop in advertising because of COVID-19, has resulted in the need to close the stations.[]

Announcing The National Emergency Library (Internet Archive)

To address our unprecedented global and immediate need for access to reading and research materials, as of today, March 24, 2020, the Internet Archive will suspend waitlists for the 1.4 million (and growing) books in our lending library by creating a National Emergency Library to serve the nation’s displaced learners. This suspension will run through June 30, 2020, or the end of the US national emergency, whichever is later.

During the waitlist suspension, users will be able to borrow books from the National Emergency Library without joining a waitlist, ensuring that students will have access to assigned readings and library materials that the Internet Archive has digitized for the remainder of the US academic calendar, and that people who cannot physically access their local libraries because of closure or self-quarantine can continue to read and thrive during this time of crisis, keeping themselves and others safe.

This library brings together all the books from Phillips Academy Andover and Marygrove College, and much of Trent University’s collections, along with over a million other books donated from other libraries to readers worldwide that are locked out of their libraries.

This is a response to the scores of inquiries from educators about the capacity of our lending system and the scale needed to meet classroom demands because of the closures. Working with librarians in Boston area, led by Tom Blake of Boston Public Library, who gathered course reserves and reading lists from college and school libraries, we determined which of those books the Internet Archive had already digitized.  Through that work we quickly realized that our lending library wasn’t going to scale to meet the needs of a global community of displaced learners. To make a real difference for the nation and the world, we would have to take a bigger step.[]

World War II’s Strangest Bombing Mission (Air & Space)

The RAF knew how to cut the power on propaganda.

eichsmarschall Hermann Göring was beside himself with anger. Years before, he had told the people of Germany that no enemy aircraft would ever cross the country’s borders. Now, on January 30, 1943, a national day of celebration marking the 10th anniversary of Hitler’s rise to power, Göring was made to look like a buffoon.

Dodging in and out of slate gray clouds, Royal Air Force bombers from No. 105 Squadron howled across Berlin. With bomb doors open and Merlin engines at their limits, the wail from a trio of de Havilland Mosquitos mixed with blasts from anti-aircraft batteries below. If everything went as planned, all that noise was going to be on the radio.

In Berlin, amid the grim news from the battlefronts in North Africa and Stalingrad, the January 30 celebration was intended to take German minds off their fallen soldiers and reversals of fortune. The Nazis were going to have a parade. Göring, one of the most powerful figures in the National Socialist German Workers’ Party, was about to deliver a speech to kick off the opening ceremonies in the capital city. British operatives knew it all. They even found out what time the Luftwaffe commandant was due to step to the podium at the Air Ministry Building—exactly 1100.

Royal Air Force leaders had dispatched orders to a pair of Mosquito squadrons experienced in low-level attacks. “I was playing [cards] in the crew room when my driver first told me we were going on an op,” Sergeant Richard Charles “Lofty” Fletcher later told reporters. “I must admit I was a bit shattered when I found out it was Berlin.”

The 400-mph Mosquitos were undertaking the RAF’s first daylight bombing attack on Germany’s largest city. Their target was not the parade route or even the Reichsmarschall himself, but something bigger. It didn’t take a top-level English spy to figure out that Göring’s remarks would be transmitted to the far corners of the Third Reich. The bombers banked and streaked towards Berlin’s Haus des Rundfunks—the headquarters building of the German State broadcasting company.

Göring and the radio building were slightly more than four miles apart—a distance that the Mosquitos could cover, going all-out, in roughly 40 seconds. And the cacophony they brought with them traveled even faster. As the mics went live and Göring began to speak, the roar of impending catastrophe became audible over the radio.[]


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Adam’s Andes DXers International certificate

Many thanks to SWLing Post contributor, Adam Smith, who shares the following certificate and writes:

I was going to share a piece of history I just came across going through some of my shortwave radio boxes. Lots of QSLs but this its a membership in ANDES DX Club!

Good times!

Thank you for sharing this bit of shortwave radio nostalgia, Adam! Any others in the SWLing Post community belong to the Andes DXers International? Do you still have your certificate? Please comment!

Radio Waves: Quantum Sensors, Sinking Mi Amigo, Submarine Radio Network, and Video Games Over The Air

Radio Waves:  Stories Making Waves in the World of Radio

Because I keep my ear to the waves, as well as receive many tips from others who do the same, I find myself privy to radio-related stories that might interest SWLing Post readers.  To that end: Welcome to the SWLing Post’sRadio Waves, a collection of links to interesting stories making waves in the world of radio. Enjoy!

Many thanks to SWLing Post contributors Kim Elliott and Dennis Dura for the following tips:


Scientists create quantum sensor that covers entire radio frequency spectrum (Phys.org)

A quantum sensor could give Soldiers a way to detect communication signals over the entire radio frequency spectrum, from 0 to 100 GHz, said researchers from the Army.

Such wide spectral coverage by a single antenna is impossible with a traditional receiver system, and would require multiple systems of individual antennas, amplifiers and other components.

In 2018, Army scientists were the first in the world to create a quantum receiver that uses highly excited, super-sensitive atoms—known as Rydberg atoms—to detect communications signals, said David Meyer, a scientist at the U.S. Army Combat Capabilities Development Command’s Army Research Laboratory. The researchers calculated the receiver’s channel capacity, or rate of data transmission, based on fundamental principles, and then achieved that performance experimentally in their lab—improving on other groups’ results by orders of magnitude, Meyer said.

“These new sensors can be very small and virtually undetectable, giving Soldiers a disruptive advantage,” Meyer said. “Rydberg-atom based sensors have only recently been considered for general electric field sensing applications, including as a communications receiver. While Rydberg atoms are known to be broadly sensitive, a quantitative description of the sensitivity over the entire operational range has never been done.”[]

Forty years ago today Sheerness lifeboat crew rescued Radio Caroline DJs from the sinking Mi Amigo (Kent Online)

It was the original ‘ship that rocked.’ But 40 years ago today (Thursday)the Mi Amigo, home to original pop pirates Radio Caroline, finally disappeared beneath the waves in a violent force 10 storm.

In a daring rescue which lasted 12 hours in appalling weather, the crew of the Sheerness lifeboat saved the lives of everyone onboard – including the ship’s canary.

Leading the operation was colourful RNLI coxswain Charlie Bowry, who was later presented with the Institute’s coveted silver medal.

It was during the day that the radio station’s 60-year-old ship started dragging its anchor and drifted 10 nautical miles onto the Long Sand sandbank off Southend.

As the tide rose, the ship started to float free. But the bottom of the boat began being buffeted on the seabed with such a force the steel plates sprung a leak and water gushed into the engine room.

When the bilge pumps couldn’t cope, the three British DJs and a Dutch engineer called the Coastguard who dispatched Sheerness lifeboat the Helen Turnbull.[]

The Radio Network that Allowed Communication with Submarines (Interesting Engineering)

Communicating with covert fleets during WWII required some special equipment.

What do you do when you need to communicate with a crew of 50 sailors submerged in a submarine in an undisclosed location across the world’s oceans? That was a difficult question to answer for Navy leaders in WWII.

Radio waves don’t easily travel through saltwater, which meant that getting active communication with a submarine crew meant making the submarine surface an antenna. This was the obvious solution, but it made a previously covert submarine now a visible target.

[…]Engineers tasked with finding a more covert solution soon discovered that radio waves with low frequencies, around 10 kHz, could penetrate saltwater to depths up to around 20 meters. They realized that if the transponders on submarines were switched to these frequency ranges, then they communicate with leadership on land.

The problem with this idea was that creating and broadcasting these low-frequency radio waves required massive antennas. Essentially, the lower the frequency of a radio wave, the longer and larger the antenna is required to be.[]

You Could Download Video Games From the Radio in the 1980s (Interesting Engineering)

Certain radio programs broadcast the raw data to video games for viewers to download.

[…]In 1977, the world’s first microprocessor-driven PCs were released. These were the Apple II, the Commodore PET, and the TRS-80. All these machines had one thing in common – they used audio cassettes for storage.

Hard drives at the time were still quite expensive, and everyone at the time had access to cheap audio cassettes. Early computer designers actually flaunted cassette storage as it aided in the early adoption of personal computers. As PCs became more common, so to did the emergence of their use as video game machines.

As the 1980s rolled around, engineers at the Nederlandse Omroep Stichting, NOS, a Dutch broadcasting organization, realized something incredible. Since computer programs and video games were stored on audio cassettes, it meant that their data could be transmitted with ease over the radio. They started taking programs and video games and setting up broadcasts where people could “download” games onto their own personal computers.

The audio that was transmitted would’ve sounded reminiscent of a dial-up modem booting up.

[…]NOS started a radio program specifically for transmitting gaming data called “Hobbyscoop,” and it became incredibly popular. The company even created a standard cassette format called BASICODE to ensure computer compatibility.

Eventually, transmitting games through computers became so popular that radio shows popped up all around the world. A Yugoslovik station called “Ventilator 202” broadcasted 150 programs between 1983 and 1986. As the practice evolved, it became less of a novelty and rather a practical way for people to share calculation programs, educational tools, encyclopedias, and even flight simulators.[]


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Smithsonian Open Access: Take a deep radio nostalgia dive!

“Radio owned by Herman and Minnie Roundtree” (Source: Smithsonian Open Access)

Many thanks to SWLing Post contributor, Balázs Kovács, who shares the following announcement:

[Check out the] Smithsonian Open Access, where you can download, share, and reuse millions of the Smithsonian’s images—right now, without asking. With new platforms and tools, you have easier access to nearly 3 million 2D and 3D digital items from our collections—with many more to come. This includes images and data from across the Smithsonian’s 19 museums, nine research centers, libraries, archives, and the National Zoo.

As Balázs points out, there are hundreds of radio photos in the archive.

What a treasure trove! Since many of us are sheltering at home, it’s the perfect time to take a deep dive into the SOA archive!  Thank you for sharing!