Author Archives: Thomas

Expectations after dusting off a radio that’s been in storage

Realistic DX-150A (Source: Universal Radio)

Many thanks to SWLing Post reader, Alfred, who writes:

I purchased a Realistic DX150 radio when it was first introduced. I used it for many years and then stored it away for some time. A few years ago I decided to use it again. After the bandspread control was repaired at a local radio shop, I used it for a short time and then stored it away.

Yesterday, I took it off the shelf to see what was on the air waves. I did not have much success in getting any broadcasts to tune in strongly/clearly. I am writing to ask what my expectations should be – given the low performance of the radio and the state of shortwave transmissions these days. The mechanical aspect of the bandspread control needs attention again. My question is: Should I be able to pick up transmissions at some good level/ quality?

Thank you for your advice and recommendations.

Alfred, thank you for your inquiry and I hope you don’t mind that I’m sharing it here publicly because I’ve been receiving so many similar questions in the past few months.

I assume with so many people sheltering at home because of Covid-19 and, suddenly, having time available to catch up on projects and pastimes, they’re pulling solid-state receivers off of the shelf and putting them on the air again!

You asked: “Should I be able to pick up transmissions at some good level/ quality?”

A simple question, with a potentially complicated answer!

A simple answer first…

If your DX-150 is still electrically and mechanically functioning as it should, and you have it connected to an effective antenna, then yes, you should be able to receive transmissions!

Caveats…

As I’ve told numerous others who have resurrected solid-state gear from storage, there’s a good chance gear that’s a few decades old could have dead or leaky capacitors. Sometimes the symptom of this is a “hum” in the receiver’s audio, but bad capacitors (or “caps” as we like to call them) can also cause less obvious issues with the radio’s overall performance. If you’ve tried everything and suspect your radio needs repair, there are some great repair technicians out there. My friend Vlado is one of them, but I think he may have paused repairs during the Covid-19 pandemic.

Radios that have sat on a shelf or in a basement for years may also have built up oxidization on switch and knob contacts. Carefully applying a product like Deoxit on contacts can make a world of difference and bring your radio back to life.

In addition, if you haven’t hooked up your radio in a couple of decades, you may be surprised by the amount of radio interference and noise (RFI) our home electronics generate. A random wire or indoor antenna that worked well in the 1970s might not work at all if you have high levels of RFI where you live. RFI has the same effect on your radio as a noisy restaurant environment has on your ability to hear a friend who is speaking at a normal volume level across the table from you. RFI can deafen your receiver. There are antennas that can help mitigate RFI, and there are also techniques you can use to help mitigate it.

Depending on where you live in the world, you will find the shortwave landscape isn’t the same as it was, say, in the Cold War years. Fear not! There are still numerous broadcasters out there, so people who say shortwave is “dead” simply aren’t listening. Check out ShortwaveSchedules.com and Prime Time Shortwave for what’s out there and where to find broadcasters on the bands. If you like music, I highly recommend Alan Roe’s guide to music on shortwave.

The Tecsun PL-380 is one of several compact portables that can be purchased for $50 or less.

If you find that you’re not hearing anything on your DX-150 (or other vintage radio)–even after following some of the advice above, yet you still want to explore the shortwaves–you might consider investing in a modern portable radio. Not only do modern portables sport a digital frequency display (which helps locate stations), but they allow you to take your listening to the field. You will be surprised what you can receive when you walk or drive to an area far away from man-made electronic noises. Tabletop radios like the DX-150 are not terribly portable. If you’re looking for some portable shortwave radio suggestions, check out this post. (Incidentally, if you found this post because you’re mainly seeking an AM/FM radio for local news and info, check out this post.)

Getting back on the air…

Alfred (and others who have recently contacted me) I hope this post gives you some helpful guidance. In truth, there are still many other issues that could affect your ability to get the most out of your vintage solid-state receiver. Let’s assume, though, that the solution is simple! Give it a go, and take your time tuning across the bands on different days and with your receiver in different locations.

My hope is that SWLing Post readers will also comment on this post with other suggestions to help you back into the world of SWLing!

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Free Radio Skybird: “One alternative to lockdown lunacy”

New KB6IBB SWL Logger version for MacOS

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Many thanks to SWLing Post contributor, Valery Titievsky, who writes:

Good news from Jeff, KB6IBB.

I’ve waited a long time for this news and it has finally happened!

Jeff has published a new release of his “KB6IBB SWL Logger” now for Mac OS.

It is available as a free download here: https://sourceforge.net/projects/kb6ibbswllogger/

Excellent news! Thank you for sharing this tip, Val!

Bruce’s passion for SWLing and single transistor regenerative receivers

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Many thanks to SWLing Post contributor, Bruce (VE3EAR), who shares the following:

I live in the village of Saltford, ON, Canada, near the eastern shore of Lake Huron. It’s a quiet location signal wise, and I’m lucky that I have enough property to erect some big antennas. My two favourites are a 1200 foot long terminated Beverage, aimed at 50 degrees true, which targets Europe and the UK. The other is a 333 foot perimeter delta-loop, apex up and oriented north-south. Both antennas are fed with RG-6 coaxial cables and impedence-matching transformers.

I use the loop with a recently acquired Airspy HF+ Discovery SDR and the Gqrx SDR software, in my iMac. I like to listen to amateur activity on 160, 80, and 40 metres, along with the few shortwave broadcast station that are still on the air. I also like to listen to the trans-Atlantic air traffic control stations in Shannon, Ireland and Gander, Canada.

I once heard a U2 spy plane returning from a mission over Russia!

My other hobby is designing and building simple, one transistor regen receivers, most of which tune the AM broadcast band, although I have built a couple covering the lower portion of the HF broadcast bands as well, just for a challenge. All my receivers are built breadboard style.

My favourite of them is one based upon the Vackar oscillator, with the addition of a diode detector and “Benny”, as is used in crystal radios.

Here is the schematic of the Vackar circuit:

The diode and “Benny” connect to the collector of the transistor, then to a pair of home made headphones using two telephone earpiece elements installed in a pair of hearing protectors. The receiver is both very selective and very sensitive. Here is a pic:

Most of the electronics are on a proto-board, which allowed easy component substitutions during the build. When I had it optimized, I decided to leave it that way! The controls, left to right, are on-off switch, regen, fine tuning, main tuning, and range selector switch, hidden behind the reduction drive. Audio is taken from the DET OUT jack, to either the headphones described above, or to an audio amplifier for listening with a speaker.

Bruce, it sounds like you certainly have an excellent spot and excellent antennas for DXing! I love regen receivers as well and radio design can hardly be more simple.

Thank you for sharing!

Radio Waves: Burning 5G, WAUK Simulcasts C-19 Radio, Remote US Ham Exams, and Guardian’s Top 10 Radio Stations

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Photo by Joshua Anderson Slate

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 Tom Daly and the Southgate ARC for the following tips:

5G Conspiracy Theories Trigger Attacks On Cellphone Towers (NPR)

Dozens of cellphone towers and equipment boxes have been set aflame in Britain, apparently by people who believe 5G technology is helping to spread the coronavirus.

Milwaukee AM Station Temporarily Simulcasting SiriusXM Channel (North Pine)

Good Karma Brands has temporarily set aside the ESPN Radio lineup on WAUK/540 (Jackson-Milwaukee) and is simulcasting a COVID-19 information from a satellite radio channel.

The temporary programming is coming from SiriusXM’s Doctor Radio and coronavirus information channels. The simulcast on WAUK began Monday, April 20. It wasn’t announced how long it will continue.

WAUK operates in tandem with “ESPN Milwaukee” FM signal WKTI/94.5 (Milwaukee), with the AM station normally continuing to carry ESPN from 7 a.m. to 3 p.m. while the FM side is in local programming.

Locally, Good Karma also owns News/Talk outlet WTMJ/620 (Milwaukee).[…]

USA: Fully-Remote Amateur Radio License Exam Administration (Southgate ARC)

The USA’s Ham Study group have released the latest update on the Fully-Remote Amateur Radio Exam Process

On March 26th, 2020, the first-ever fully-remote amateur radio exam was held to demonstrate the capabilities of these technologies and align with the needs of the W5YI VEC that authorized the trial.

Several other VE Teams have begun administering fully-remote exams using ExamTools.org along with video conferencing systems.

Read the Press Release at
https://blog.hamstudy.org/2020/04/fully-remote-amateur-radio-license-exam-administration/ […]

10 of the best music radio stations around the world (The Guardian)

Thousands of radio DJs are employed around the globe to play Anglophone pop and rock. If there’s such a thing as “world music” to them, it’s REM and Queen.

But there are many more radio stations around the world that play music from their own cultures, past and present, mainstream and marginal. When it comes to virtual travel, music is arguably the easiest and most enjoyable way to transport your brain out of Covidland to places you’ve visited – or plan to – in person.

The net is pretty chaotic, with dozens of aggregators and formats. But here are 10 soundscapes to explore. Turn up the volume to Mexican cantina level.[…]

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Radio Caroline’s Founder, Ronan O’Rahilly, dies aged 79

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Photo of Ronan O’Rahilly 16 August 1967 by Eric Koch / Anefo

(Source: BBC News)

The founder of Radio Caroline – the first pirate radio station off the UK – Ronan O’Rahilly has died aged 79.

His death was announced by the current Radio Caroline, which still exists off the Essex coast.

The station was founded in 1964 to compete with the BBC and launched the careers of many well-known DJs, achieving enormous popularity.

Mr O’Rahilly, who lived in Ireland, had been diagnosed with vascular dementia in 2013.

Radio Caroline was the first of several pirate radio stations that challenged BBC radio’s dominance in the 1960s.

The station played pop music all day, while the BBC only played pop for an hour a week.

[…]After the Marine Broadcasting Offences Act was passed in 1967, Radio Caroline continued to broadcast from ships until 1991, when the Ross Revenge was shipwrecked off the Kent coast

The station, which started broadcasting again on medium wave in 2017, helped pave the way for modern commercial radio.[…]

Click here to read the full story at the BBC.

More about hacking VGA cables to make binocular ferrite cores

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A few days ago, we posted an a short article showing how Oscar hacked a VGA cable to make a binocular ferrite core for his homebrew NCPL/Youloop antenna. Many thanks to SWLing Post contributor, Grayhat, who explored this clever hack a little further:

Hi Thomas, Having some time in my hands Sunday afternoon I decided to try pulling out the ferrite chokes from a VGA cable I had around, and while doing so, I decided to coarsely document the process with some pics.

Figure 1

The first thing to do is use a cutter to carefully cut around the “washer” shaped plastic at the connector end of the choke (fig.1, #1,#2, #3 above), then on the same side, after cutting the plastic also cut the inner conductors (fig.1, #1).

Move to the other side of the choke, gently cut around the “washer” w/o cutting the inner conductors, now pull the cable to extract it from the choke (fig.1, #3), repeat the process for the other choke.

Now look at the “cans” containing the chokes, one side of those will show a “cap” (fig.1, #4), insert a small screwdriver into the center hole and gently ply to one side to raise the cap and extract it (fig.2, #1).

Figure 2

The result will be as in fig.2, where #1 is the closing cap, #2 is the ferrite choke and #3 is the “can” containing the choke. Repeat the process and you’ll have two ferrite chokes as shown in fig.3 (the VGA connector is there to give an idea of the dimensions):

Figure 3

At this point, use some tape (duct tape will be a better idea, I used clear tape just to make an example) to tie the two ferrites together as in fig.4 and you’ll have your “binocular ferrite”:

Figure 4

Willing to use whatever you have there to wind the transformer, you may now extract the tiny insulated wires from the VGA cable (fig.1, #3, see wires) and use them for the windings.

Notice that other cables may use different choke “cans” which may need to cut a larger portion around the flat faces at the ends. But remember that in any case, those are just “snap-in” cans containing the ferrites, so with a bit of attention and patience, it shouldn’t be difficult extracting the ferrites.

Based on a little online research, it sounds like the ferrites used to choke the VGA cables (HDMI ones too) are generally type #31.

Looking at some #31 datasheets it appears that while #73 is works fine at frequencies below 50MHz, the #31 is best suited for the 1-300MHz range.

This means that #31 won’t be the best pick for mediumwave, although if one doesn’t have another choice… well, go for that! Also notice that the ferrite permeability is different:1500 for #31 and 2500 for #73. This means that we’ll need to increase the number of windings to achieve acceptable signal transfer, otherwise the transformer loss will make our antenna deaf.

One might try increasing the number of windings to say 8:8 or 16:16; as long as the winding
ratio will remain the same, there won’t be problems (although the resulting bandwidth will become narrower).

Thanks for documenting and sharing this, Grayhat! Since most of us have more time on our hands at home, I think it would be worth experimenting with the number of windings to see how it affects the antenna performance. That’s a clever thought, too, to use the VGA wires to wind the Balun. As long as the cable is long enough for the amount of turns, it’s certainly the most efficient use of resources!