Category Archives: Tutorials

D.I.C.A.: Giuseppe’s latest homebrew portable antenna

Many thanks to SWLing Post contributor, Giuseppe Morlè, who shares the following antenna project:

Dear Thomas and SWLing Post Friends ,

I’m Giuseppe Morlè, iz0gzw, from Central Italy, Formia on the Tyrrhenian Sea…
Some time ago I had drawn this minimal HF antenna on paper…

I took advantage of the New Year’s Eve rain to be able to build it with the usual leftover scraps…

The system consists of a 35 cm tube with two separate windings of telephone cable on it, 2.5 m on each side, green and white…in the center I connected the 4 ends to X…

The green lead with the white and the white with the green to the variable capacitor and the other two leads to the RG58 cable that goes to the receiver.

I started the test and noticed that the agreement was possible from 7 to 21 MHz…

I then placed a long ferrite inside the tube…

I noticed a strengthening of the signal and consequently of the noise picked up and the chord dropped to 3.2 MHz.

Tests inside my shack showed decent reception on all ranges…in the evening on the balcony on 80 m. I could perfectly listen to a QSO between Italian stations.

Everything is still in the experimental phase and I think I will try this minimal system also in QRP transmission.

In this first video I explain how this minimal antenna is made:

The second video concerns a 20 meter test by car. The antenna is placed on the dashboard of the car inside:

In the third video, I explain how it works without the ferrite and with the ferrite inside the tube:

In this video you can see the test on 40 m. outdoors on the roof of the house:

The tests are carried out at home in order to understand what can be achieved in an environment that is difficult to receive.

I will do more outdoor tests and I think this small minimal antenna will receive better. I will keep you informed.

Thank you all for your attention and I wish you all a new year full of satisfaction.

’73 de Giuseppe iz0gzw.

Fascinating, Giuseppe! I love all of these brilliant little antennas you design out of your “junk” drawer! We look forward to hearing more about this antenna and any modifications you make to it!

Spread the radio love

TomL’s Guide to Audio Plugins For Radios: Part 2 – SDR Recording

Many thanks to SWLing Post contributor, TomL, who shares the following guest post. Click here to check out all of the posts in this Audio Plugin series:

Audio Plugins For Radios, Part 2 – SDR Recording

by TomL

I started investigating using the old Kenwood transceiver to send audio to my laptop and process the receive audio using VST Host for a number of functions: Noise reduction, Equalization, reduce Sibilances and fading distortion, increase presence of vocals without sounding boxy, etc.  It was a qualified success depending on what VST apps I used, in what order they were used, and what settings each of them were set to.  In this episode of ongoing discovery, I will attempt to show how easy it is to OVER-process the shortwave broadcast audio plus comparisons to my regular Audacity post-recording treatment.

Audio Examples

I noticed for the first time that the SDR creates a somewhat compressed file which can be seen when comparing the Waveforms of SDR vs. VST Host output files.  This means that the unprocessed SDR file will always appear to sound louder because of this compression.  This loss of Dynamic Range makes it harder to do the comparison.  Therefore, the Audacity-only examples below are reduced 3dB or 5dB to maintain apparent loudness.

Example 1:  KBS Weekend Playlist – S6-S9 signal, somewhat severe fading and moderate polar flutter.

SDR Console 3.2 using my usual NR4 set to 2dB Reduction, 30% Smoothing, and 3dB Rescale plus a Blackman-Harris-7, 5.3 kHz filter.

AUDACITY file is using my usual Audacity noise reduction:

VST version 2: Used my first set of VST apps.  Sounds harsh with hash-noise and overdriven:

VST version 3: Used way too much bass, too much grunge, attenuated highs, still overdriven:

VST version 4: Using a different order to the Denoiser apps, added in Modern Exciter app, cut back on some bass but still too much, and overly forward sounding midrange:

VST version 5: My current Baseline setup.  Adjusted the Denoiser apps, less extreme bass & treble, adjusted the De-Esser app, set the midrange to be less forward with just a single setting:

To my ears, Audacity processing is nice but as discovered before, sounds compressed and does not reduce some of the other problems inherent in shortwave signal fading and loss of musicality.  It sounds utilitarian.  Also, the noise is a bit more gnarly.

Versions 2-5 go through iterations of listening to the exact same segment over and over (and over) and trying different VST apps and settings.  I think my comments are mostly accurate next to each version.  However, you may think differently and perhaps prefer the sound of one of the other versions?

Example 2: Encore Classical Music, WRMI (fading S9 signal) – Audacity vs. Version 5 VST settings.  VST is quieter and sounds less harsh than the Audacity version.  A generally more smooth sound.


Example 3: RCI in Russian, S7-S9 with moderate polar flutter – 7kHz filter in SDR Console but VST Host is using BritPre, an analog preamp using a 6 kHz low pass filter to try to reduce DSP filter “ringing”.  It shows some interesting possibilities.

Example 4: RCI in Russian – Music from the same broadcast and VST Host setup in Example 3.  The screeching flute is under more control and strings more defined in the VST version.


I like the results of the audio processing that eventually ended up with “version 5” (plus the possibilities at 7kHz, too).  It is not Earth-shattering but is an incremental improvement in my opinion (there is always room for improvement).  I can use it in a simple Workflow anytime I want to record something off of the SDR.  Also, I had already been using Voicemeeter Pro, a software audio mixer.  It is setup with different profiles to do SDR, Ham, FM Broadcast, and now, VST Host audio routing.  This process took a long time but seems satisfactory to use as a Baseline setup, which then can be tweaked slightly depending on various types of audio coming from the SDR.  These changes in VST Host can be stored as their own unique profiles for audio processing.

However, a word of warning!  Messing with Windows audio Sound settings and mixer software is potentially a confusing process and one can easily end up with a spaghetti-pile of conflicting connections, no audio output, doubled echo output, distortion, way too loud, way too soft, etc.  If you start this experimentation, make sure to write down your current Windows Sound settings, both the Playback and the Recording settings for each item listed.

Having an SDR radio + Voicemeeter + VST Host is a very flexible setup.  I can now safely say that the only thing I need Audacity for is to Normalize the peak audio to the -1 dB broadcast standard volume, which is a HUGE time saver.  The SDR Console IQ files can be scheduled and processed from there at a later time.  Also, the use of Voicemeeter Pro allows me to switch when to use VST Host anytime I feel like it, and Voicemeeter Pro comes with its own (manually engaged) Recorder.

Part 3 of this series will discuss Technical details for my setup.  Your setup may need different settings or you may find a better way than I did.  This will take some dedicated time.

Happy Listening and 73’s,


Click here to follow all of the articles in TomL’s audio plugin series.

Spread the radio love

TomL’s Guide to Using Computer Audio PlugIns with Older Radios

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

Using Computer Audio PlugIns with Older Radios

by TomL

Older radios have a way to get audio out to speakers or another audio input device, usually just a headphone jack.  Software for processing audio are plentiful and very useful tools, called VST’s.  Furthermore, most Plugins were made for Musicians needing full frequency spectrum capability.  I will use my Kenwood TS-590S amateur radio as a test case.  I have used its speaker output to a cheap Behringer UCA-202 RCA to USB converter (it has its own volume control to keep it from overloading).

Amazon Link: Behringer UCA202

My Windows 10 Sounds Properties sees this audio as “3-USB Audio CODEC” which I have enabled on a physical USB hub with individual power switches for each port.  Thanks to Steve (K1GMM) and his YouTube channel (K1GMM Green Mountain Maniac) for describing how to use Windows plugins for processing either Receive or Transmit audio.  This article only focuses on Receive audio.

For my simpler needs, I have chosen to use VST Host.  It will run the small “apps” that usually have a file extension of .VST or .DLL.  I downloaded it right from Steve’s website:

I then downloaded a number of plugins suggested by Steve on his web site (“More” Menu pulldown, DAW’s/VST DOWNLOADS).  Each VST file can be copied to a central directory/folder on your computer and all read from the same place inside the VST Host.  Most of these are Windows types but there are some for Linux if that is something you use.  I found that VST Host does NOT like a write- protected directory, so it and the VST’s reside in my top-level Documents directory.

My resulting “chain” of VST’s process the audio from my 3-USB Audio CODEC in a sequential manner, which are:

  • ModernAmplifier (a Limiter to keep strong signals from overloading the processing)
  • ReaFir (an interesting “Subtract” feature where I cut down on the “roar” around 800-1200 Hz)
  • Bertom Denoiser Pro (EXCELLENT static & background noise reducer)
  • TDR Nova (a powerful, well-made Compessor & DynamicEQ combo)
  • Sennheiser-AMBEO-Orbit (a Binaural soundscape).

Once VST Host is installed, create a separate folder for the VST files.  Now just copy the VST3 or DLL file for each of the apps downloaded like the ones I list above.  If you have a 32-bit version of Windows, you will have to use the VST’s that are 32-bit, not 64-bit.

In VST Host, set the Wave Input and Output and sampling rate (Menu: Devices—Wave).  In my case it is the aforementioned 3-USB Audio CODEC for (Microphone) Input Port and VoiceMeeter Aux-Input for the Output Port.  The sampling rate is set to 48000  (You can choose Output to your “Default Speakers” which should be in the list if you do not use an extra mixer software like I do).

Now, go to Menu: File, Plugins and load each plugin that you want to use.  The VST3 or DLL files should all be in the same directory that you made earlier.  You may have to tell VST Host where to find them by setting the Plugin Path (Menu: File, Set Plugin Path…).

Now, once you have all the VST apps opened, you will notice that all of their individual outputs go directly to the VST Host Output.  Not good, since your computer will not have enough cores to parallel-process all of these apps at the same time.  So, Unchain them all by right-clicking on each app and choosing “Unchain”.

Now you will see all of the yellow connecting lines gone.  Arrange (click/drag) each app in sequential order on the screen.  Starting from the bottom up, right click on the app just above VST Output and choose Chain After…

Repeat up the chain, choosing the one above it to Chain After until you are left with a Daisy-Chain of apps, each output going to the Input of the next app in your desired order of processing:

Now turn on the radio to get audio going through the chain of apps.  Tweaking each app is part of the tedious process of learning if an app will help or not.  Just replace and Chain After in the order you want with other VST apps that you find more helpful.  Tinkering with this should yield some satisfactory results if you do not overdo applying features in each app.  To save the layout and VST settings, go to Menu: Performance, Save As and give it a name to store in the data file shown (just a name since it will put it into the default line 000 for you).  You can choose this in future sessions from the main pulldown Menu below File. (Note: It is called “Performance” because this stuff was written for Musicians to save their home studio music along with the settings for shaping the music tracks; 99% of planet earth calls this a “Layout”, a la, Microsoft Office)

Here are two examples of sound from the radio without processing and then adding in each app over a few seconds.

LZ1AA from Bulgaria. Processing 10 secs., off 15 secs., on again 8 secs.


CHU Canada. Processing on, space, processing off. Notice a little “water” effect since AM Broadcast needs quite different settings compared to SSB Ham Radio.

You can check out Steve’s “Green Mountain Maniac” YouTube channel and see for yourself what can be done with sound processing for Radio.  Some of his techniques can be used with old shortwave radio receivers as long as it has a working headphone jack or AUX Out jack:


Cheers and Happy Listening,


Spread the radio love

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

Spread the radio love

Introducing the amazing SULA: An affordable unidirectional DX-grade loop antenna that you can build!

Many thanks to SWLing Post contributor extraordinaire, 13dka, who brings us 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 will focus on construction notes. The third and final article will essentially be a Q&A about the SULA antenna. All articles will eventually link to each other once published.

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 SULA Part 1:

Introducing the Small Unidirectional Loop Antenna (SULA) 1-30MHz

A small and simple, unidirectional and DX-capable loop “beam” for SWLs!

by 13dka

In early June, Andrew (grayhat), SWLing Post‘s resident antenna wizard suggested a variation of the “cardioid loop” on the SWLing Post message board: The original “cardioid loop” is a small loop receiving antenna deriving its name from a cardioid shaped (unidirectional) radiation footprint. The design is strikingly simple but it has a few downsides: It relies on a custom preamp, it needs a ground rod to work and it is unidirectional only up to 8 MHz.

Andrew’s version had the components all shuffled around and it did not only lose the ground rod, it also promised a nice cardioid pattern over the entire shortwave, from a small, diamond shaped loop. Wait…what? It can be made using parts available on Amazon and your DIY store:

You need some 3m wire and PVC tubes to create a support structure to hold the wire, a 530 Ohm resistor and a 9:1 balun like the popular “NooElec One Nine”. Since it’s a “lossy” design, adding a generic LNA like the NooElec “LANA HF” would help getting most out of it. When you put that all together you have what sounds like an old shortwave listener’s dream: a small, portable, tangible, and completely practical allband shortwave reception beam antenna with some more convenient properties on top, for example, it is a bit afraid of heights.

That sounded both interesting and plain crazy, but the .nec files Andrew posted were clearly saying that this antenna is a thing now. Unfortunately Andrew suffered a little injury that kept him from making one of those right away, I on the other hand had almost all the needed parts in a drawer so I ended up making a prototype and putting it through some of its paces, with Andrew changing the design and me changing the actual antenna accordingly, then mounting it upside down. Let me show you around:

  •  Small, diamond shaped wire loop (with 76cm/29.92″ sides), needing as little space as most other small loops.
  • Unidirectional with a ~160° wide “beam” and one pronounced minimum with a front/back-ratio of typically 20dB over the entire reception range 1-30MHz.
  • Moderate height requirements: It works best up to 3m/10′ above ground, where it gives you…
  • …a main lobe with a convenient flat takeoff angle for DX
  • Antenna is comparatively insensitive to ground quality/conductivity.
  • Wideband design, works best on shortwave and is pretty good up to 70cm.

A functional small beam antenna for shortwave reception that’s just as small and possibly even more lightweight (prototype:~250g/9oz) than your regular SML, that can be easily made out of easy to obtain parts and easily carried around for mobile/portable DXing and due to its cardioid shaped directional pattern also for direction finding, a “tactical” antenna that’s also doing DX? Unlike conventional, Yagi-Uda or wire beams it can achieve a low takeoff angle at only 3m/10ft height or less, the front/back ratio is typically better than that of a 3-element Yagi, with a particularly useful horizontal pattern shape. That it’s rather indifferent to soil quality could mean that more people get to reproduce the good results and being a real wideband antenna is making the SULA an interesting companion for multiband radios and SDRs. Really? A miracle antenna? Is it that time of year again? If I had a dollar for every….

Continue reading

Spread the radio love

Guest Post: An Introduction to DXing the MF Marine Bands

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

Spread the radio love

Guest Post: 13dka Explores the International Beacon Project

Many thanks to SWLing Post contributor, 13dka, who shares the following guest post:

In search of benchmark signals: The International Beacon Project

by 13dka

If you – like yours truly – like to tinker with antennas and radios to get the most out of them, you likely have your own set of reference stations. If this is a new concept for you – reference stations are whatever stations you deem apt to check propagation, the general function of your radio, when trying to improve reception or comparing radios… They are ideally always on when you need them and come in various strengths and distances on several bands from all over the world. Traditional sources for that are of course time signals and VOLMET stations on HF, even though the latter are giving you only two 5-minute slots per hour for testing reception from a specific region and the former have their own specialities here in Europe:

A typical scene on 10 MHz, captured at home 30 minutes after the full hour: BPM voice ID from China mixed with something else, then Italcable Italy kicks in on top of some faint murmur possibly from Ft. Collins, in winter some South American time stations may stack up on that together with splatter from RWM 4 kHz lower…

A reliable source of grassroots weak signals is particularly desirable for me because I enjoy proving and comparing the practical performance of radios at “the dike”, a QRM-free place on the German North Sea coast. In the absence of manmade noise and the presence of an ocean adding 10dB of antenna gain, finding benchmark stations with “grassroots” signal levels turned out to be a different challenge than it used to be: With somewhat sizeable antennas the stations tend to be (too) loud there, even with the baseline ionospheric conditions under a spotless sun in its activity minimum. In short, my old benchmark stations didn’t work so well anymore and I had to find something new. Continue reading

Spread the radio love