Category Archives: How To

Tom’s Recommendations: Earbuds and EQ Settings for Shortwave Listening

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

Earbuds for Shortwave Listening

by TomL

A few years ago I had bought the discontinued Sennheiser MM 50 earbuds for a cheap price on Amazon to use in my various radios.  The portable radios in particular can use more fidelity because of their small, raspy speakers.  I also like to listen without bothering others around me who might not want to listen.  And earbuds are a LOT more comfortable for my ear lobes than any over-the-ear headphones I have ever used.  Furthermore, the old Apple iPhone 4 earbuds were very harsh to listen to.  However, a trade-off is that, generally, earbuds are somewhat fragile; one of the two pairs of MM50’s died through mishandling.

I was generally happy with them while listening to Shortwave broadcasters with a mix of news/talk and music.  I especially liked them on Mediumwave listening; stations can sound surprisingly good when playing music.  Then I tried using these earbuds on my Amateur Radio transceiver, a Kenwood TS-590S.  I was impressed how clear they sounded with a lack of distortion, although there was too much bass.  Fortunately, Kenwood supplies USB connected software with an TX & RX 18 band EQ (300 Hz spacing, not octaves).

Here is a frequency response chart I found from for this model:

One of the notable things about these earbuds is the total lack of distortion.  Most likely one of the reasons they sound so clear on Shortwave, which has many LOUD audio spikes.

I had not wanted to get Bluetooth earbuds.  However, I had recently upgraded my cell phone and NO headphone jacks anymore!  So, while I do not use Bluetooth yet for radios, I can see a time in the future to get a Bluetooth transmitter to plug into a radio with a headphone jack.  I am reluctant since I do not like having to recharge my earbuds and I put in a lot of radio listening time.  Am I supposed to buy two Bluetooth earbuds and swap while charging?  Maybe in the future.  And also, am I supposed to buy a Bluetooth transmitter for every non-Bluetooth radio I own?  Not likely gonna happen.

In the meantime, I ordered cheap wired earbuds from Amazon.  I had a $5 credit for trying Prime, so when I saw these Panasonic ErgoFit wired earbuds (RP-HJE120-K) for slightly over $10, I said to myself, “why not?”.   Supposedly wildly popular, they are one of the most rated products on all of Amazon with 133,821 ratings/opinions (perhaps Russian bots?!?!?).

Here is a frequency response chart from for these Panasonic earbuds:

You can see comparatively that the bass response in the very good Sennheiser MM50’s is much stronger, being good music earbuds.  But for voice articulation, not as much, even though they have no distortion.  The Panasonic ErgoFit’s have more modest bass, less of a dip in the lower midrange audio frequencies, and more importantly, has a peak near 2500 Hz and its harmonic 5000 Hz.  The highest highs are also modest compared to the Sennheiser model.  This general frequency response to “recess” the bass and treble frequencies and peak the 2500 Hz is very useful for voice intelligibility.

As described by the famous speaker-microphone-sound-system maker, Bob Heil relates what he learned from the scientists at Bell Labs many years ago.  Speech intelligibility is enhanced when audio is compensated for our natural human hearing.  Equalizing below 160 Hz, reducing the 600-900 Hz region, and peaking the 2000-3000 region centered at 2500 Hz will increase intelligibility dramatically.  The story goes that Bell Labs was tasked by parent AT&T with finding out why the earliest phones in the 1920’s sounded so muffled and hard to understand.  After many experiments, the scientists found the most important frequencies for our ears + brain to comprehend speech.  In other words, our ears are not “EQ-flat” like a scientific instrument is. Continue reading

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Giuseppe experiments with mediumwave loop induction

Many thanks to SWLing Post contributor, Giuseppe Morlè (IZ0GZW), who writes:

Dear Thomas and all friends of the SWLing Post,

I’m Giuseppe Morlè from Formia on the Tyrrhenian Sea…

I wanted to share this experiment of mine with all of you by tuning the medium waves with two separate loop cassettes and each for itself by exploiting the principle of induction between two conductors placed next to each other.

I superimposed one cassette on the other by matching the windings of the medium waves–each variable works only for its own box.

I’m tuning the Algerian JIL FM station on 531 kHz with the Tecsun H-501X connected to the box below…then, passing to the top box, the one without any physical contact with the receiver, I tuned this station again centering it perfectly thanks to the induction that creates between the two close windings.

My video will clarify any doubts and I would like to receive your comments about it.

My constructions are the result of continuous recycling and spending very little to get a good yield.

You can view this video below or on my Youtube channel:

[Note that you can translate this video into your language via YouTube’s automatic subtitles. Click here to learn how to do this.]

I’m available for any clarification…
Thanks to all of you and I wish you good listening.
73. Giuseppe Morlè iz0gzw.

Thanks so much for sharing your antenna experiments with us, Giuseppe! 

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Giuseppe upcycles and improves a homebrew MW antenna

Many thanks to SWLing Post contributor, Giuseppe Morlè (IZ0GZW), who shares the following:

Dear Thomas and Friends of SWLing Post …

This is Giuseppe Morlè. As always, I try recycling what I have and improving upon antennas I’ve built in the past. This is one way we radio lovers can experiment. Many years ago, I made an antenna only for medium waves; by adding a circuit, I can now listen to short waves.

I took advantage of a small frame that I recovered from an old commercial FM / AM stereo receiver by removing its coils for medium waves and I wound around it only two coils sufficient to have a frequency range from 3.5 to 18 MHz.

I remember that the antenna in question also receives medium waves as it was born.

I chose this small frame because I wanted everything to be small in order to carry this compact antenna everywhere.

Unlike my other projects for SW and MW, which have a cable that carries the SW signal to the receiver, this time I used the induction that is created around one end of the loop, which I spiraled to get inside the stylus of my Tecsun PL-660 and which then transfers the signal to the receiver.

I did some tests on my balcony the day after a strong storm and I noticed that the propagation was absent but I still wanted to make sure that everything was working.

[Note that you can translate this video into your language via YouTube’s automatic subtitles. Click here to learn how to do this.]

I will keep you updated on other tests on more favorable days of propagation … I still invite you to follow me on my Youtube channel.

I wish everyone a good listening …
73. Giuseppe Morlè iz0gzw.

Many thanks, Giuseppe. I, for one, love all of your homebrewed and recycled antennas. This one is no exception! What a fun project. I love how you use what you have and aren’t afraid to experiment! Thank you for sharing.

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Guest Post: Monitoring Digital Selective Calling (DCS) with YADD

Many thanks to SWLing Post contributor, Don Moore–noted author, traveler, and DXer–for the following guest post:

Photo by Borderpolar Photographer

Monitoring DSC with YADD

By Don Moore

(The following article was originally published in the April/May 2022 edition of the Great Lakes Monitor, bulletin of the Michigan Association of Radio Enthusiasts. An all-band listening club, MARE publishes a bi-monthly print bulletin and a weekly e-mail loggings tip-sheet. The club also holds regular get-togethers, picnics, and DXpeditions, generally in southeastern Michigan.)

There are dozens if not hundreds of different digital modes used for communication on the MF and HF bands. These aren’t broadcasts you want to listen to unless you like to hear weird tones, beeps, warbles, and grinding noises interspersed with static. Digital modes are for monitoring, not listening. And monitoring them requires having software that does the listening for you and converts the noises into something meaningful – like the ID of the station you’re tuned to. The learning curve to DXing digital utilities can be steep. There are lots of modes to identify and the software can be complicated to learn. Some broadcasts are encrypted so you can’t decode them no matter how hard you try. But the reward is lots of new stations and even new countries that you wouldn’t be able to add to your logbook otherwise.

One of the easiest digital modes to DX is DSC, or Digital Selective Calling. DSC is a defined as “a standard for transmitting pre-defined digital messages.” Look online if you want to understand the technical specifications that specify the values, placement, and spacing of the tones. The result of those specifications is a string of three-digit numbers like this:

125 107 125 106 120 105 120 104 000 120 022 120 041 000 002 022 020 041 108 002 053 020 080 108 006 053 021 080 070 006 118 021 126 070 126 118 126 126 126 126 126 126 126 126 126 126 117 126 112 126 117 117 117 112 109 125 108 125

Each three-digit value represents either a digit or a key word and the positions of the values map to the various fields contained in the message. This message, which was received on 8414.5 kHz, is a test call from the tanker Brook Trout to the coastal station Coruña Radio in Spain. The sender and destination are not identified by name but rather by their nine-digit MMSI (Maritime Mobile Service Identity) numbers – 538006217 for the vessel and 002241022 for the coastal station.


Logging DSC stations requires three pieces of software. First you need a decoder program that turns the noises into numbers and the numbers into meaning. There are several free and commercial options but the most popular one for beginners is YADD – Yet Another DSC Decoder. YADD is free and easy to set up and while YADD can be used by feeding the audio from a traditional radio into your computer, the most common use is with an SDR. That’s what I use and what I will describe here.

Second you need an SDR application and an SDR. I prefer HDSDR for most of my SDR use but I like SDR-Console for digital work. But any SDR program will work if you can feed the audio to a virtual audio cable. And that’s the final thing you need – a virtual audio cable to create a direct audio connection between your SDR application and YADD. There are several different ones available but I recommend VB-Cable. Your first VB-Cable is free and that is all you need to run a single instance of YADD. If you want to expand you can buy up to four more cables from them later. Continue reading

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How Jake configures SDR# to listen to Encore classical music

Many thanks to SWLing Post contributor, Jake Brodsky (AB3A), who shares the following guest post:

How I Listen to Encore on Radio Tumbril

Listening to Classical music on shortwave is a challenge. It has loud and soft parts to the music. There may be selective fading. It isn’t a simple thing.

Also, configuring a software defined radio such as the highly configurable SDR# is not trivial. Note to readers: SDR# has been updated a lot recently and the noise reduction features are vastly improved. Kudos to Youssef Touil for all the hard work on this software. He continues to impress me with every update.

So I have some suggestions for those who are interested in listening:

First, get a decent set of over-the-ear headphones. Don’t rely on laptop speakers. They’re usually not designed for audio fidelity.

Set the radio for DSB reception with Lock Carrier and Anti-Fading checked. I also set the bandwidth to cover about 11 kHz or thereabouts.

On the Audio tab I uncheck the Filter Audio option. I’m going to rely on IF filtering to do my work for me.

Next, find an empty channel on the band where you will be listening to the program. Enable the IF Noise Reduction feature, set it to HiFi, and then set the threshold so that the noise floor is reasonably low. If you set the threshold too high, you’ll lose the higher frequency audio and there will be artifacts from the noise floor that I find unpleasant. A little bit of noise reduction is good, but more is not better.

I also enable the IF Filter/notch processing window to handle any stray birdies from switching mode power supplies. However, if not needed, I turn that feature off.

I turn off the AGC. And then I set the volume level to something reasonable, not too loud, not too soft, but just barely able to hear the noise floor.

Then I tune in the program. I was listening to the Sunday Evening (Monday 0200 UTC) broadcast from WRMI on 5950 kHz. There was some fading going back and forth. However, I took the atmospherics in stride, as if it were part of the experience. The broadcast from this evening
ended with the Pastoral Symphony from Beethoven. There were a few fades and there were a few swells, all due to atmospherics as the signal faded to the noise floor and emerged from it. But there was very little distortion. (thanks to the excellent engineers at WRMI).

The experience was actually sublime.

This is why I listen to shortwave broadcasts.


Jake Brodsky, Amateur Radio Station AB3A

Click here for Radio Tumbril schedule and updates.

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Jason’s solution to a false low battery indication on the Tecsun H-501x

Many thanks to SWLing Post contributor, Jason Walker, who shares the following advice:

H501x Tecsun Battery Issue – False Low Battery Indication – Solution

As a H-501x owner I have found a solution to ‘false’ low battery indications on the radio, having tried several high quality batteries to lengthen the runtime, even a high capacity 3500mAh Fenix, without much success.

Last week, I noticed that when the radio was physically moved or tapped, the battery indicator would vary to low and radio cut out. I have traced this to a poor battery terminal connection (poor spring strength primarily) on the battery bays A & B.

By using a very light sanding of the positive battery contacts in the radio with fine sandpaper and cleaning of the 18650 battery terminals, not only does the issue go away, but the radio runtime improves significantly and battery capacity indicator returns to full.

I would be interested to know if anyone else has come across this issue? This may also be a cause of low H501/x runtimes mentioned in other posts.

Stronger battery springs with higher tension would improve the battery to terminal connection, as a product improvement suggestion for Tecsun or perhaps a local mod?

Jason Walker, Christchurch, New Zealand

Thank you for sharing this, Jason! No doubt a very easy modification that produces meaningful results. Again, many thanks!

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Small Unidirectional Loop Antenna (SULA) Part 3: Questions & Answers

Many thanks to SWLing Post contributor extraordinaire, 13dka, who brings us Part Two of a three part series about the new SULA homebrew antenna project. This first article describes this affordable antenna and demonstrates its unique reception properties. The second article focuses on construction notes. This third and final article will essentially be a Q&A about the SULA antenna. 

This wideband unidirectional antenna is an outstanding and innovative development for the portable DXer. I love the fact that it came to fruition via a collaboration between Grayhat and 13dka: two amazing gents and radio ambassadors on our discussion board and here on the SWLing Post. So many thanks to both of them!

Please enjoy and share Part 3:

Part 3: SULA Q&A

by 13dka

Q: Where can I ask questions, discuss all aspects of the the SULA or collaborate in its further development?

A: There is a thread dedicated to the SULA in the new message board:

Q: Since the antenna is “lossy”, what’s the point of having a “beam”?

A: The answer is once again “SNR”: First off, remember that the LNA is there to make up for most of the losses. Secondly, this is all about the noise pickup, 20dB less gain/more losses outside the main lobe means also a reduction of atmospheric/cosmic/whatnot QRN and of course everything manmade from all these sides. The wide horizontal lobe is more or less one hemisphere horizontally, but the flat-ish vertical pattern makes that only a slice of it. In other words, there will be less QRN and QRM pickup from the back and the top. The idea is that the SNR will ideally increase more than the preamp’s noise figure will cost and it often sounds like this is what actually happens. Of course it’s also nice that you can turn an unwanted signal down using the more or less pronounced notch in the backside pattern up to 21 MHz – also very helpful for direction finding.

Q: Do I need a rotor?

A: It depends. If you are one of the lucky few still having a low-QRM-environment at home and you want to put it in the backyard, you really may want to be able to turn it remotely. If you’re using it portable you can simply rotate the mast manually. If you have local QRM or can’t mount it very far away from your or other houses, you may want to rotate the back of the antenna towards that source, leave it at that position forever and enjoy what’s coming in on the pretty wide main lobe of the antenna. The horizontal lobe covers more or less half of the horizon, depending on your stations of interest and location you could get away with never turning the antenna at all.

Q: Is it better than the XYZ loop?

A: Hey, that’s exactly what I wanted to ask you! 🙂 Even though the SULA is very similar in appearance and performance to a good SML working in ideal (ground conductivity) conditions, the SULA is a pretty different animal with a different behavior: Regular small loops, besides being bidirectional, can lose quite a bit of their low angle sensitivity over “poor” ground while the SULA is supposed to be retaining its properties better over any type of ground. Also, while many SMLs are tuned for VLF through the lower portion of the shortwave, the SULA complements those with quite uniform (good) properties up to 30 MHz and beyond.

Q: I have an end-fed random wire or dipole strung up from the house to a tree etc. – can the SULA beat that?

A: That’s quite possible. To get low takeoff angles from horizontal wire antennas you need to string them up at least 1/2 wavelength high, that’s 20m/66ft on 40/41m, 10m/33ft on 20m and so on. If you can’t do that, the SULA may be your ticket to listen farther beyond the horizon. Also, wire antennas are often strung up to match space restrictions or avoid QRM vectors and that way you may end up with some directionality in directions you don’t want, or no directionality at all when the wire is too low. Another noteworthy point is the ground: For most horizontal antennas, better ground means a considerable higher takeoff angle so the dipole needs even more height for low angles. The SULA’s takeoff angle benefits a little from the better ground and only gets a little worse over poor ground.

Q: Do I really need an LNA?

A: I hope so? Of course it depends… if you are going to try this antenna in a very noisy environment, the LNA may have little to no benefit. The noise is limiting your “radio horizon” to very loud signals anyway and for those you may not need an LNA, ever. On the other hand, the antenna is very lossy and in a quiet environment where noise is not an issue at all, weak signals may drop below the sensitivity threshold of your receiver without the LNA. The less noise you have, the more you’ll be able to benefit from an LNA. You will also need one when your radio isn’t all that sensitive, similar to the requirements to run a YouLoop. Andrew kept the loop impedance as constant as possible in order to allow any low impedance coax preamp to work behind the Balun. Any LNA with 20dB of gain should do, as per usual, better stuff may bring better results.

Among the sparse offers for decent shortwave LNAs, the NooElec LANA HF seems to be the only decent LNA sold via Amazon. It’s comparatively low-cost and unlike the other offers on Amazon, ready to be powered via Bias-T or even via Micro-USB and therefore happy with 5V. Since I also had the balun from the same company I could simply connect that all with a couple of these cute little SMA plumbing bits and it worked. The downside is its unknown but perceivably low resilience against intermodulation (low 3rd-order intercept point), this is usually not a problem with such a small loop but it can be in the presence of nearby transmitters.

If you do have nearby transmitters and don’t mind sourcing an LNA from Europe, Andrew recently pointed me to preamps from here. They offer a moderately priced preamp with a 2N5109 transistor (based on the W7IUV design) for a high IP3 value and low noise, which is also available in PCB-only and fully assembled versions including a compartment. They also offer Bias-T boxes.

Another alternative would be – the design (using a GALI-84 MMIC) is promising more headroom than the LANA HF (which seems to use the lower voltage GALI-39), but needs 12V power like the W7UV preamp above. This LNA is available in a ready-to-use box as well.

Q: What is special/different about this antenna? There are already very similar designs!

A: It’s supposed to be simpler and more compact/portable, and it seems to deliver more consistent results over the entire coverage range in different usage environments than similar designs. The SULA was designed to be made with things that are particularly easy to obtain, or which were already obtained — many of us SWLs have some of that Nooelec stuff in our drawer anyway, even when (or because) we’re not habitual antenna builders and balun winders. Now making a better balun and buying a better preamp is not hard and could even bring better results but the point is that you don’t have to. In summary, this is not meant to be a miracle antenna, just number of compromises re-arranged to create a particularly uncomplicated, small, unidirectional loop antenna that aims for DX, for apartment dwellers and DX nomads like me.

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