Category Archives: Radio History

History of the Radio Intelligence Division Before and During World War II

Many thanks to SWLing Post contributor Mike, who writes:

Good afternoon, Thomas. Recalling that there have been a few postings on the SWLing Post over time on the FCC’s Radio Intelligence Division, I thought this might interest you and some readers. I just came across this (I don’t even remember what linked me to it) and have only briefly looked reviewed it, but the manuscript appears to be pretty interesting. https://www.qsl.net/w3df/sterling/ridhist.pdf

Additional history can be found here: https://www.qsl.net/w3df/sterling/dfh1.html.

An interesting local (to me) tidbit on page 19: “It [RID] patrolled the outside of the Oak Ridge, Tennessee installation, the scene of the Manhattan Project but without the personnel knowing what atomic developments were being made inside.“

73,
Mike in Knoxville,
KW1ND

Fascinating! Thank you for sharing this, Mike.

Podcast Explores History of Parque do Rodeador

SAQ at 100: Celebrating a Century of Global VLF Communication

Grimeton SAQ turns 100!

On July 2, 2025, the SAQ Grimeton Radio Station in Sweden celebrates its centennial — a hundred years of quiet transmissions that have bridged continents and eras.

Built in 1925, this UNESCO-listed radio station still transmits Morse code using a pre-electronic VLF generator.

A silent voice of peace across the globe.

SAQ to air at 100th anniversary on July 2nd 2025: https://alexander.n.se/en/celebrate-100-years-with-saq-grimeton/

English program: https://alexander.n.se/wp-content/uploads/2025/06/Jubileumsdagen_Grimeton100_en.pdf

SAQ transmits telegrams worldwide on 17,2 kHz at 11.00 CEST (09.00 UTC) and 15.00 CEST (13.00 UTC). The startups begin at 10.30 CEST (08.30 UTC) and 14.30 CEST (12.30 UTC).

Learn more:

WA2XMN Revives Armstrong’s Legacy with 90th Anniversary Broadcast on 42.8 MHz

42.8 MHz WA2XMN FM Goes On The Air!

6/19/2025

By Conrad Trautmann, N2YCH

Stephen Hemphill, WA3ZAE, the owner of Solid Electronics Laboratories, fired up a vintage FM tube Phasitron transmitter on 42.8 MHz to put WA2XMN on the air at exactly 12:30 pm EDT today from the famous Armstrong Tower in Alpine, New Jersey. “W2XMN” was the call sign of Edwin Howard Armstrong’s experimental FM station that went on the air in 1936. “WA2XMN” is the official FCC call sign for the station Hemphill constructed with the cooperation of the tower site owners to commemorate Armstrong’s contribution to radio, Frequency Modulation.

W2XMN building at the Alpine Tower site

Hemphill explained that he attended a Society of Broadcast Engineers meeting that was celebrating Armstrong’s accomplishments, which sparked the idea of going on the air again on that original frequency. He thought it would be perfect to aim for the 70th anniversary of the first public broadcast of wideband FM. That anniversary celebration and broadcast was held on June 11, 2005. Today’s broadcast marks 90 years since that first FM Broadcast and 20 years since the commemorative event.

Hemphill built a transmitter based on the design of a General Electric BT-1-B, but on the lower frequency than what we now know as the standard FM band. Once turned on, the transmitter made 250 watts with no problem with a little headroom to spare and after warming up and settling in, had less than one watt reflected into 400+ feet of 1 ¼” transmission line into a vertical “ringo” antenna on the top, Western facing arm of the famous tower.

Stephen Hemphill poses with his Phasitron FM transmitter tuned to 42.8 MHz

Dual Eimac 4-250a power amplifier tubes

Armstrong Tower in Alpine, NJ (the vertical antenna is up there, trust me)

The audio broadcast today was mostly replays of the 70th anniversary event recordings. A temporary studio was set up in the tower site office building. The event was also streamed live over the internet.

WA2XMN temporary studio and audio processing.

Stephen Hemphill at the controls

The main audio mixing console used was a Gately Electronics Attache Case six channel mixer. Audio processing was done with a vintage Orban Optimod 8100A.

Gately Electronics Attache Case Mixer (apologies to all audio engineers for the pinned meters)

During the event, a web site address for enthusiasts to provide reception reports was given out. While we don’t have those reports yet, I contacted an amateur radio friend who was able to hear the station clearly 61 miles away in Ronkonkoma, NY on the eastern end of Long Island. That’s pretty good coverage for 250 watts!

Coupled with the special event broadcast was the annual picnic gathering of the New York Chapter of the Society of Broadcast Engineers, Chapter 15. Roughly 45 people attended and in addition to seeing the WA2XMN transmitter, they also got a first hand look at a few of the old Empire State Building FM Master antenna elements. Here’s a photo of your author standing next to one for perspective. I’m 6’ 5”.

To read more about this antenna and its history, visit this page researched and written by Paul Thurst, KH2R, owner of the “Engineering Radio” blog.

Conrad, N2YCH with an Alford antenna element from the Empire State Building

Radio KWID and the War in the Pacific

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Many thanks to SWLing Post contributor Jerome van der Linden, who writes:

For my bedtime reading I have recently been going through a book (“Radar Yarns”) which contains lots of stories, many of them humorous, about Australians that were involved in setting up radar stations during WWII around the coast of Australia as well as New Guinea.

There has been a mention of the guys in one location listening to the BBC, and of them sometimes having a shortwave radio where they once listened to Tokyo Rose. But I came across a sentence which made me wonder, and I thought someone in the SWLing post community might be able to throw some light on it: “According to an announcement on Radio KWID, San Francisco, it was a great victory for the American forces. It was broadcast as part of the 4th July celebrations in 1943 that Woodlark and the Trobriand Islands (which includes Kiriwina) had been captured with ‘little or no resistance’”.

So, I had originally asked Thomas to raise a post on this as I had not heard of KWID in my 65 odd years of SW listening, but then….a couple of days later – while watching some TV with the wife – I was doing some googling on my phone, and came across an article published in 2008 by Radio World: https://www.radioworld.com/columns-and-views/a-voice-across-the-pacific-kwid-amp-kwix. This has answered my own question!

I recommend all those who are part of the SWLing Post Community and who have an interest in the history of SW broadcasting should read the above article, you will get a lot more from that than if I were to quote parts of it. It was apparently written by Dr Adrian M Peterson who used to feature on Media Network occasionally (Radio Netherlands, Jonathan Marks). It would seem that KWID was one of the founding stations / transmitters of the Voice of America, and it was well heard in the Pacific, which explains why it was mentioned in the book I was reading. There was also one sentence in the article that caught my eye: “the physical size of both transmitters was the same at 68 feet long”. Can you imagine that?!

Then lastly, I’ve learned an amazing coincidence: Dr Adrian M Peterson was born in South Australia, in 1931: that’s my home state in Australia!

Jerome van der Linden

Fascinating, Jerome! Thank you for sharing this!

The Secret Listeners

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Our friend Bill Meara at SolderSmoke just shared a link to an excellent Hackaday article highlighting Britain’s “secret listeners”—the skilled amateur radio operators who intercepted enemy transmissions during WWII. These unsung heroes quietly monitored Axis communications, contributing to vital wartime intelligence.

This piece offers a compelling look into how amateur radio skills were used for national defense and how listening—often overlooked—played a key role in the war effort.

We actually featured the 1979 BBC documentary, “The Secret Listeners” eleven years ago (!!!) here on the SWLing Post. It’s a brilliant video:

How Radio Carried the News of D-Day: Broadcasts from June 6, 1944

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American GIs heading toward the shoreline of Omaha Beach around June 7, 1944. (Photo Courtesy of The National WWII Museum)

Today marks the anniversary of D-Day—Operation Overlord—the Allied invasion of Normandy on June 6, 1944.

If you’ve never listened to how the news broke here in the U.S., the Internet Archive hosts a remarkable collection of recordings from that historic day. It’s fascinating to hear the unfolding coverage in real time—an extraordinary window into the role of radio during one of the most pivotal moments in history.

Complete Broadcast Day – D-Day (June 6, 1944)