Monthly Archives: February 2018

Treasure hunt: Seeking Somali radio recordings from 2010

Okay SWLing Post readers: I need you to dig through your off-air recordings for something pretty obscure…

Over at the Shortwave Radio Audio Archive, I frequently receive inquiries from educators, researchers, historians, and enthusiasts looking for very specific off-air recordings, often for some worthy project or other. It’s quite a thrill when I can lay hands on just what’s being sought in our rather deep recordings archive.

I recently received just such an inquiry from producer Meghan Keane at NPR, and though we were not able to provide immediate help, I’m quite intrigued by the subject and thus not quite ready to give up the search. Meghan writes:

My name is Meghan Keane and I’m a producer for NPR’s Invisibilia. I’m working on a story about Somalia and music, and am currently looking for some archival sound.

Around 2010, many radio stations in Somalia broadcasted animal noises and gun shot noises to protest Al-Shabab. I am hoping to find audio of that to use in my story. Please let me know if you have any leads!

Fascinating stuff. I do recall a news story about Somali radio broadcasts including animal and gun shot noises back in the day, but I never actually heard a broadcast on shortwave or mediumwave.

Post readers: Can you help Meghan track down such a recording? If you can, please comment and/or contact me!

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Solar Minimum: A “relatively large” sunspot makes appearance

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(Image: spaceweather.com)

(Source: Southgate ARC)

With Solar Minimum right around the corner, sunspot counts are at an almost 10-year low. So it came as a surprise yesterday when a relatively large sunspot emerged near the sun’s eastern limb.

AR2699 has a primary dark core larger than Earth with many smaller magnetic condensations trailing behind it, in all stretching more than 75,000 km across the sun’s surface.

Rare “solar minimum sunspots” are capable of intense explosions just like sunspots during more active phases of the solar cycle.

Visit Spaceweather.com for more information and updates.

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Can you help Luke identify this radio noise?

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Many thanks to SWLing Post contributor, Luke Perry, who writes:

I am experiencing a issue with my shortwave reception at my part-time home. I have been helping out my mother so I have brought over my Sony portable, along with the Sony active antenna. I have a constant ‘clicking’ sound starting at about 5 kHz or thereabouts that make listening unbearable. As the video shows the problem is non-existent below 4 kHz. I tried moving the radio throughout the house thinking it could be something in the room and still get the same interference.

I was hoping that the filter on the active antenna would help but it does little to remedy the problem. I have no issues with MW or FM reception at all.

I have made a short YouTube video to document the problem in the hopes that one of the blog readers can identify it. I looked online at other instances of RFI and I could not find one that is similar. Hope that someone can help me!

https://youtu.be/OcEWAkdfmWw

Click here to view on YouTube.

After listening to the first few seconds of your recording, I thought it sounded a bit like an electric fence controller. However the interval between pops is nearly random, which suggests a different source. I suppose it’s possible a faulty fence controller could do this. I believe the only way you could defeat this noise (without shutting it down at the source) would be to use a radio with a durable noise blanker. Of course, I know of no portable radios with an NB function (though most SDRs and tabletop receivers include an NB).

Post readers: Can help Luke ID the source of this noise? Does it sound familiar to you? Please comment!

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XHDATA D-808: using an external longwire antenna for MW

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Many thanks to SWLing Post contributor, Mad Radio DXer, who writes:

I want to bring to the attention of your readers & fellow XHDATA D-808 owners that it can accept an external antenna on MW without the need for any modifications. This I found out during a DXpedition to the field when I used around 50 metres of longwire.
I have some videos to prove this. The first is the difference between the external longwire antenna vs the internal ferrite antenna…

Click here to view on YouTube.

The second video is pretty much the same as the first, but this time I am tuning on a lower frequency of the MW band. Also I show that not only can the 3.5mm antenna input be used to connect an external MW antenna, but the internal whip antenna too.

Click here to view on YouTube.

The third video shows the difference between the XHDATA D-808 vs the Degen DE1103 PLL (using the external MW antenna trick). when using an external antenna for Medium Wave. In my opinion there is not much difference between them reception-wise, but the D-808 has the advantage of being able to select tighter bandwidth filters for less QRM from stations on adjacent frequencies.

Click here to view on YouTube.

These days I am more of a MW DXer than on shortwave. I am thrilled to have found out that the XHDATA D-808 can accept an external antenna for Medium Wave in stock form, since my understanding when I read some reviews was that it could not unless an internal modification was done. I will do more experiments of MW reception with the D-808 on my next DXpedition.

I want to add a few more points…

The D-808 does not work with an external longwire antenna for Long Wave. I tried this & will upload a video of the result soon. However, I tried using my LW induction antenna at home & it did get stations which it could not using the internal ferrite antenna on its own. Again a video of that will be upcoming.

I tried using a Wellbrook antenna for improved MW reception on the D-808 & unfortunately it does not work well. There was too much background noise, & there were harmonics + images all over the band. I would instead recommend using a good passive antenna like a longwire rahter than a strong active one.

It is recommended to use 25 metres or more longwire for best results. Obviously, the more longwire used means the lower the frequency gain for reception.

I cannot guarantee that this will work for all XHDATA D-808 units in case, for eg, some have different firmware versions. All I can say is it does not hurt to try, but bear in mind what I said about the longwire antenna length. Also a nice quiet location away from manmade noise helps even more to minimise any QRM.

I hope this has been helpful & useful to all XHDATA D-808 who like me, are really into MW DXing.

I’m happy to hear that you’re enjoying MW DXing and that the XHDATA D-808 is serving you well! Over the years, my DXing habits shift and change, but I’ve always included a healthy amount of mediumwave DXing in the mix. Especially when propagation on HF is dismal, I head down to the MW band for some action! Thanks again for sharing your videos and tip!

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Gregg finds a case for the Sangean ATS-909X

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Many thanks to SWLing Post contributor, Gregg Freeby, who writes:

I recently purchased a Sangean ATS-909X and while I really like the radio, I wasn’t too impressed with the envelope pouch/case it came with for protecting the radio. I really like the leather case of the Tecsun PL-880 but it appears to have one major flaw, it only holds the radio and no accessories. I like to have everything all in one neat kit. So, I set out to see what I could find that would fit my 909X.

It didn’t take me long to find this little gem [on Amazon.com].

By removing the CD envelope inserts (they’re just sewn in) there’s just enough room for the radio, power transformer, earbuds and reel antenna. I’ve attached a couple photos to show the case and what fits inside. I added a little strip of soft green foam I had around the house to take up some of the extra space around the radio while also providing a little more protection.

While the case is only faux leather it is very sharp looking, black with white stitching, and is a big improvement over the supplied case, particularly since everything I need is in one complete package.

By the way, I read on the SWLing Post a tip from you regarding the need to use fresh batteries to boost the sensitivity of this radio and you could not be more correct. In fact, using the AC adapter is almost a must for pulling in weak signals. And as others have said, an external antenna really helps but for me I’ve found that running on AC power makes the biggest improvement in performance.

Many thanks for sharing your tip, Gregg! That’s a stylish case! I imagine there are many readers out there who even have CD/DVD cases they no longer use for storage and could be put into service as a radio case.

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The AirSpy HF+ R3 bypass modification

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After SWling Post contributor, Guy Atkins, posted the survey results of his excellent Elad FDM-S2 vs AirSpy HF+ weak signal comparison, I received a few questions about the AirSpy HF+ “R3 Bypass” modification Guy mentioned in his post.

Guy has not yet performed the modification on his HF+–neither have I–but he points out that others have noted it: “significantly boosts sensitivity of the HF+ from longwave up to about 15 MHz, without any noted overload issues.”

I reached out to AirSpy president, Youssef Touil, for a little more insight about this modification. Youssef replied:

During the early phases of the design R3 was a place holder for a 0 ohms resistor that allows experimenters to customize the input impedance. For example:

A 300 pF capacitor will naturally filter the LW/MW bands for better performance in the HAM bands

A 10µH inductor would allow the use of electrically short antennas (E-Field probes) for MW and LW

A short (or high value capacitor) would get you the nominal 50 ohms impedance over the entire band, but then it’s the responsibility of the user to make sure his antenna has the right gain at the right band

A custom filter can also be inserted between the SMA and the tuner block if so desired.

Click to enlarge. (Photo source: RTL-S1DR.com)

R3 and the nearby resistors have been intentionally left outside of the RF shield, and their size was picked to be big enough to allow anyone to play with them. You will notice the size difference with the rest of the components.

In general, unless one knows what he’s doing, it’s not recommended to alter a working system. “If it’s working, don’t fix it”. But, we are hobbyists, and not doing so leaves an uncomfortable feeling of something unachieved. Most brands addressing the hobby market leave some tweaks and even label them in the PCB.

The main purpose of the HF+ is the best possible performance on HF at an affordable price. This is to incite HAMs to get started with this wonderful technology while using an SDR that isn’t worse than their existing analog rig.

The MW/LW/VLF crowd may have slightly different requirements, but that can be addressed by shorting a resistor.

Regards,

Youssef Touil

Thank you, Youssef, for replying to my inquiry so quickly and thoroughly.

No doubt, I too will eventually modify R3–it’s very difficult not to experiment, especially when a product was designed with the experimenter in mind.

I really feel like AirSpy has knocked it out of the ballpark with the HF+. For those of us primarily concerned with HF performance, this SDR is very hard to beat–especially at its $199 price point!

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FCC authorizes wireless power transmission experimental station

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Many thanks to an SWLing Post contributor @experimradio who shares the following information from the FCC website:

Experiment authorized by FCC: WJ2XGB, 1800 kHz

https://apps.fcc.gov/els/GetAtt.html?id=202374&x=. [PDF]

Our Texzon Wireless Power™ system allows the Earth itself to be used for clean, safe and efficient transfer of power between any two points on the globe, wirelessly. The system represents a paradigm shift in the science of electromagnetics.

http://www.texzontechnologies.com/

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