Tag Archives: Radio History

Paul Litwinovich on “The Life, Decline and Possible Rebirth of AM”

Many thanks to the SWLing Post reader who noted this latest post by Paul Litwinovich at WSHU (Paul is frequently referenced here on the Post).

A short excerpt:

“AM occurs elsewhere in nature. A lightning strike or manmade electrical discharge will produce a burst of electrical noise that varies in amplitude. Since AM radios are designed to detect variations in amplitude, this is why they are prone to interference from such things. AM held sway as the primary method of modulating a radio wave up to WWII, not only for broadcasting, but for all types of radio communications.

Every vintage consumer radio, be it standard broadcast or shortwave, up to WWII, received amplitude modulated signals. Nowadays, AM broadcast stations are associated with lower quality audio, but such was not always the case. Receiver design really came of age in the 1930s with the superheterodyne circuit and advancements in loudspeaker design. The grand floor consoles of the late 1930s leading up to WWII were capable of producing audio that was very good, even by today’s standards, the only exception being that they were monaural, as stereo technology was still a ways off.”[…]

Litwinovich’s article is a must-read as he gives a concise overview of amplitude modulation, AM vs. FM, and even covers current proposed uses of the broadcast band (something we’ve also recently mentioned).

Click here to read The Life, Decline and Possible Rebirth of AM.

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Jagadish Chandra Bose and the invention of radio

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Jagadish Chandra Bose in Royal Institution, London

Many thanks to SWLing Post reader, A Black, for sharing the following article from the excellent Hackaday blog:

J.C. BOSE AND THE INVENTION OF RADIO

The early days of electricity appear to have been a cutthroat time. While academics were busy uncovering the mysteries of electromagnetism, bands of entrepreneurs were waiting to pounce on the pure science and engineer solutions to problems that didn’t even exist yet, but could no doubt turn into profitable ventures. We’ve all heard of the epic battles between Edison and Tesla and Westinghouse, and even with the benefit of more than a century of hindsight it’s hard to tell who did what to whom. But another conflict was brewing at the turn of 19th century, this time between an Indian polymath and an Italian nobleman, and it would determine who got credit for laying the foundations for the key technology of the 20th century – radio.

Appointment and Disappointment

In 1885, a 27-year old Jagadish Chandra Bose returned to his native India from England, where he had been studying natural science at Cambridge. Originally sent there to study medicine, Bose had withdrawn due to ill-health exacerbated by the disagreeable aroma of the dissection rooms. Instead, Bose returned with a collection of degrees in multiple disciplines and a letter of introduction that prompted the Viceroy of India to request an appointment for him at Presidency College in Kolkata (Calcutta). One did not refuse a viceroy’s request, and despite protests by the college administration, Bose was appointed professor of physics.

Click here to continue reading on Hackaday…

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Fessenden Christmas Eve Commemorative Transmissions

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This was reported in the ARRL Newsletter:

Brian Justin, WA1ZMS, will again put his 600 meter Experimental Station WG2XFQ on the air on for a Christmas Eve commemorative transmission. WG2XFQ will transmit on 486 kHz from Forest, Virginia, to mark the 109th anniversary of Reginald Fessenden’s first audio transmission. Historic accounts say Fessenden played the violin — or a recording — and read a brief Bible verse. It’s been reported that other radio experimenters and shipboard operators who heard Fessenden’s broadcast were astounded.

Justin will conduct a run-up to this year’s event starting at around mid-day Eastern Time on December 23. The “official” Christmas event will begin on December 24 at 0001 UTC (the evening of December 23 in US time zones) and will continue for at least 24 hours. Justin said he plans to repeat the commemorative transmissions on New Year’s Eve and on New Year’s Day.

Fessenden’s transmitter was an ac alternator, modulated by placing carbon microphones in series with the antenna feed line. Justin’s homebuilt station is slightly more modern, based on a 1921 vacuum tube master oscillator power amplifier (MOPA) design. Listener reports are appreciated and may be sent directly to Brian Justin, WA1ZMS, at his QRZ.com address. (Brian Justin, WA1ZMS, built this replica circa-1920 transmitter, capable of CW and Heising modulated AM. Photo by Brian Justin)

While I have not heard Brian’s transmission before, I have actually heard a transmission on the experimental frequencies between 465 – 515 kHz. I never expected to be able to hear anything due to extremely high local noise, but one night the propagation gods smiled upon me and the evening was exceptionally quiet. I listened on my Elad SDR receiver over and over to the Morse Code signal which was extremely weak, but mostly readable. I confirmed with Multipsk software, verifying I was indeed hearing one of the experimental stations out of Connecticut.

For information regarding the 500 KC experimental project you can follow this link.

Why not give a listen? You just might be surprised like I was to hear something on this band, and you could add a little Christmas Eve radio memory to your collection!! 73, Robert

Robert Gulley, AK3Q, is the author of this post and a regular contributor to the SWLing Post. Robert also blogs at All Things Radio.

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Video: The Skelton HF Transmitting Station

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Many thanks to Jonathan Marks, who shares this short video about the history of the Skelton HF Transmitting Station:

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How Far We’ve Come: Looking Back at Radiotelegraphy, 1939 Style

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It’s often insightful to look to the past to fully appreciate the current technology we take for granted.

When we tap a favorite contact’s name in our mobile phone–even for someone on the other side of the world–we can be talking to them within seconds, with clarity that’s often the equal of visiting face-to-face. Perhaps Skype or FaceTime is more your style? Yawn… just another two-way, real-time video session. The fact that the other person is thousands of miles away no longer makes you pause at the wonder of it all. Continue reading →

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Archived recording of Marchese Marconi

A timeline of radio in the UK

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Many thanks to SWLing Post reader, Daniel, who shares a link to this article on the BT website:

From Marconi and the transistor radio to DAB: the history of radio in the UK

93 years ago this week, the BBC made its first radio broadcast. We look back at some of the most significant events in radio’s history.

On November 14, 1922 the British Broadcasting Company began its first radio broadcast. Since then the radio landscape has changed dramatically.

Radio is still an incredibly popular medium. According to Ofcom’s 2015 Communications Market Report, nine in ten UK adults listen to the radio each week. We listen for an average of 21.4 hours a week, but the way we do this has changed.

Families had to huddle around the radio in the 1930s, but now we can listen to the radio anywhere, anytime using our smartphones. We look at some of the most significant milestones of British radio over the last 93 years[…]

Click here to read through the entire article and timeline at BT.com.

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