Tag Archives: Guest Posts

Guest Post: Control of Electromagnetic Radiation (CONELRAD)

Many thanks to SWLing Post contributor, Bob Colegrove, who shares the following guest post:

Control of Electromagnetic Radiation (CONELRAD)

As recalled by Bob Colegrove

In his comment on my recent posting, Tinkering with History, Mario noted the dial on the featured radio, the General Electric P755A, sported two small triangles, one between 6 and 7, and the other between 11 and 14. He noted that these were civil defense markers intended to show the frequencies of 640 kHz and 1240 kHz, respectively, and that these were characteristic of AM radios produce in the US roughly between 1953 and 1963. Since two full generations have been born and raised to adulthood since that time, and I can’t find any related posting here, I thought it might be useful to bring this subject to light.

In spite of otherwise economic prosperity and general wellbeing, these years were nevertheless filled with anxiety about the prospects of all-out war. Children of the time (myself included) were being shown how to hide under their school desks, and some of their parents were going so far as to construct air-raid shelters in their basements, and stock them with enough provisions to supposedly outlast any catastrophe. So it was that CONELRAD came into being in 1951. The idea was, that in case of a National emergency, all radio and TV stations would go off the air, and only certain medium wave radio stations would stay on either 640 kHz or 1240 kHz. They would remain on for a few minutes and then other stations would take over in a round robin arrangement – this to deter homing by hostile bombers. Needless to say, quickly changing over transmitters and antennas to one of these two frequencies did not bode well for the equipment and there were many failures in subsequent tests. Note that, as originally conceived, the system did not provide for local weather emergencies or other situations.

The banner photo at the top of this posting shows a portion of the Hallicrafters S-38E receiver which conformed to Government law of the time required for marking all AM dials. An S-38E just like it was my first genuine multi-band radio in 1959. Assuming good alignment, the dots next to the CD triangles indicated the 640 kHz and 1240 kHz frequencies. When a test came on, you didn’t have to fish for it, since CONELRAD was the only service transmitting.

Going back to the radios described in Tinkering with History, GE took this one step further. The figure below shows a portion of the dial on a GE P806A. Note the nub on the outer edge of the dial under the triangle at 1240 kHz. There is another nub on the edge at 640 kHz. Together with the raised triangular dial pointer molded on the cabinet, they provided a braille system, so that someone visually impaired could easily tune to a CONELRAD frequency.

As technology improved, CONELRAD transitioned to the Emergency Broadcast System (EBS) in 1963, and subsequently the Emergency Alert System in 1997. A more thorough description of CONELRAD can be found on Wikipedia https://en.wikipedia.org/wiki/CONELRAD. Reprint of an April 1955 Radio & Television News article describing the construction of a transistor CONELRAD receiver is at https://www.rfcafe.com/references/radio-news/conelrad-radio-television-news-april-1955.htm.

Guest Post: “Tinkering with History”

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Many thanks to SWLing Post contributor, Bob Colegrove, who shares the following guest post:

Tinkering with History

By Bob Colegrove

One of the attractive aspects of radio as a hobby is that it has so many specialties to channel our time. Just for the sake of classification, I would group these into two categories, listening and tinkering. I think the meaning of each category is fairly intuitive. Probably few of us approach our interest in radio in the same way. Most of us have dabbled in more than one listening or tinkering specialty. Perhaps we have been drawn to one particular area of interest, or we may have bounced around from one to another over a period of time. I know the latter has been my case.

Tinkering might start with a simple curiosity about what makes the radio play, or hum, or buzz, and progress to an obsessive, compulsive disorder in making it play, hum or buzz better. Unfortunately, over the past 30 years or so, the use of proprietary integrated circuits, as well as robotically-installed, surface-mounted components have greatly short-circuited what the average radio tinker can do. For example, I have noticed a lot more interest in antennas over that period, and I think the reason is simple. The antenna is one remaining area where a committed tinker can still cobble up a length of wire and supporting structure and draw some satisfaction. But the complexity and lack of adequate documentation have largely kept newer radio cabinets intact and soldering irons cold. Bill Halligan knew you were going to tinker with his radios, so he told you how they were put together. The fun began when you took your radio out of warranty. If you did get in over your head, there was usually somebody’s cousin not far away who could help you out. The following is a sample of how one resolute tinker managed to overcome the problem of locked-down radios in the modern age. Continue reading →

Presentation: Crystal Radio History, Construction, and Contesting

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Many thanks to SWLing Post Contributor, David Day (N1DAY), who shares the video presentation below, offering even more insight into his most recent guest post on the topic of crystal radio DXing.

David has also posted this presentation on his website and notes that he’s happy to share the presentation slides without copyright. David notes:

[…]I have purposely not copyrighted this work so that anyone is free to modify it as they see fit. The only thing I ask is that if you make changes that you do not copyright the derivative work as your own intellectual property so that others can benefit from your knowledge and build upon it as well.

That’s brilliant, David! Thank you.

Presentation:

Click here to view on YouTube.

Click here to check out N1DAY’s website.

Guest Post: Mark explores a 1983 Voice of America information pack

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Many thanks to SWLing Post contributor, Mark Hirst, who shares the following guest post:

VOA Information Pack 1983

by Mark Hirst

Introduction

A recent guest post on this blog by Jock Elliott asked the question, ‘Why Listen to Shortwave?’

The comment I left at the time was my interest in how nations view themselves, and how they project that view to the world. This might be in the form of cultural exports like music, or teaching us about famous people or revered institutions in their country.

When I first started listening to shortwave in the early eighties, I never got into the habit of asking for QSL cards, being quite thrilled enough to receive programme guides in envelopes stamped with the postmark of other countries.

At the time, the primary stations for me included Radio Netherlands, Radio Sweden, Swiss Radio International, and the Voice of America. While most might send a small leaflet about their country with a frequency schedule, the information pack I received from the Voice of America stands head and shoulders above the others.

I thought readers might be interested in a brief description of this pack and with it a glimpse back into the world of 1983.

Please note that as you read the following sections, you can click on the images to view a larger version.

Package Contents

The package arrived in a manila envelope, with the logo and address of the VOA printed in the top left corner. In the top right corner is the logo of US Mail, with a declaration that postage and fees where paid for by the US Information Agency.

Package contents included:

Compliments Card
VOA Sticker
Steering the Course Magazine
VOA Magazine
May-October 1983 Programme Schedule

VOA – The Voice of America

This guide begins by outlining the mission of the VOA, emphasising its aim to be an authoritative and reliable source of news. Continue reading →

Guest Post: Comparing the Reuter Pocket and the Icom IC-705 from an SWL’s perspective

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Many thanks to SWLing Post contributor, Uli (DK5ZU), who shares the following guest post:

SWL with a Reuter Pocket and the Icom IC-705

by Uli (DK5ZU)

Some time ago I asked how the IC-705 performs on longwave and I got some great feedback. Thanks a lot again. Since the HAM bug bit me again, I wanted to do SWL and HAM Radio portable with one rig. I started with SWL some weeks ago (just before the bug bit). I acquired a second hand Reuter Pocket RDR 51 Version B2. It is a standalone SDR Receiver 0 … 30 MHz / 50 ..71 MHz, and in my B2 version it has also FM (Stereo/RDS) and Digital Audio Broadcasting (DAB). You may find the detailed specs here:
https://www.reuter-elektronik.com/html/pocket.html

The Reuter Pocket could, at one point, be configured as an QRP Transceiver, but it is no longer supported. There is a new RDR 52 small tabletop models, which can be ordered as a transceiver, too. But due to Covid related supply chain problems and price changes for the components, the new model is currently postponed.

The IC-705 is available, though. And for portable HAM operations it is a no brainer; obviously with a high price tag, but comparable with a new Reuter RDR 52 tabletop. And since my budget for the hobby is limited, I thought about funding part of the IC-705 price by selling the Reuter Pocket. But I wanted to do a side-by-side comparison so I ordered the 705 and was able to check them both on one antenna. The goal was to compare their sensitivity and selectivity on the lower bands: BC on AM and HAM bands for SSB. I did not compare CW since I am not a CW operator.

The antenna is a MiniWhip from PA0RDT which works quite well on the lower bands.

This comparison is not at all scientific and reflects just my opinion and what I heard. But anyway, there may be some people out there interested in this. So much for the intro.

Let’s start with my overall findings. Continue reading →

Guest Post: Crystal Radios – Construction, Listening, and Contesting

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Many thanks to SWLing Post contributor, David Day (N1DAY), for sharing the following guest post:

Crystal Radios – Construction, Listening, and Contesting

By David Day – N1DAY

The date was November 2, 1920 and the world was about to change forever when radio station KDKA out of Pittsburgh PA made its first broadcast of election results from the 1920 presidential election. For the first time in history people knew who won the election before reading about it the next day in the newspaper. Radio had arrived!

However, hearing the election results was not as easy as powering up an AM radio receiver because radio electron tubes had only been invented a few years earlier and they were still too expensive for most people to afford in a radio set. After KDKA’s historic broadcast, large 50,000 watt stations began popping up in all major cities around the world. Even though a tube-driven radio was not yet commonplace, many people listened to these stations on their crystal radios. The frenzy around radio in the 1920’s was not unlike the excitement around cell phones and the internet today. If you didn’t have one, you were simply living in the past.

A family listening to a crystal radio in the 1920’s

Fortunately, in the early 1920’s the crystal radio had been around for a while and it was easy to make or purchase a completed set on a limited budget. The beauty of the radio was that it was a passive device needing no power source other than the radio station’s broadcast that was received by a good antenna about 50 feet long and 15 or so feet above the ground. Crystal radios derived their name from use of galena crystals as detectors. Continue reading →

Guest Post: An Introduction to DXing the MF Marine Bands

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Many thanks to SWLing Post contributor, Don Moore–author of Following Ghosts in Northern Peru–for the following guest post:

Monitoring the MF Marine Bands

By Don Moore

For me, DXing has always been about the challenge of receiving difficult-to-hear radio stations, regardless of the type of station or frequency range. In my five decades in the radio hobby I’ve logged a lot of different kinds of stations – shortwave broadcast, medium wave, shortwave utility, longwave beacons, etc. But some of my favorite catches have been in the upper end of the medium frequency range.

Technically speaking, medium frequency (MF) is the range from 300 to 3000 kHz and includes the standard medium wave (AM) broadcast band. The upper end of the MF band, from 1600 to 3000 kHz (except for a small portion reserved for amateur radio), has always been assigned to various types of utility uses including broadcasts and other voice communications from regional maritime stations. And while digital modes and satellites have done a lot to change the nature of communication with ships at sea, there is still a lot of good human-voice DX to be heard.

Several dozen stations, mostly in Europe and North America, broadcast regularly scheduled marine information broadcasts in the MF range. These broadcasts are usually between five to ten minutes in length and include weather forecasts, navigational warnings, and other notices to keep ships at sea safe. On occasion it’s possible to hear two-way voice communication here between ships and shore stations, although that’s much less common today.

The Equipment

Nothing special is needed to DX the marine MF band other than a receiver that covers the frequency range and can receive USB mode (which all these broadcasts are in). However, for reasons explained below, I highly recommend using an SDR to make spectrum recordings of the entire band to go through later. Continue reading →