Tag Archives: Guest Posts

Mario shares a short review of the Airspy HF+ Discovery SDR

Many thanks to SWLing Post contributor, Mario Filippi (N2HUN), who shares the following guest post:

Author’s Airspy HF+ Discovery (small black box to the left of the laptop)

A Short Review of the Airspy HF+ Discovery SDR

by Mario Filippi (N2HUN)

I recently purchased an AirSpy HF+ Discovery. As a SWL for over 60 years who’s owned many shortwave radios by manufacturers such as Drake, Yaesu, Icom, Zenith, Kenwood, Panasonic, Sony, Radio Shack, Grundig, CountyComm, MFJ, Sears, AOR and have used a number of different SDRs such as the RTL-SDR.com, HackRF, NooElec and many other rudimentary inexpensive first generation SDR dongles, I feel the AirSpy was an excellent choice. It cost $169 plus shipping.

For LW/MW/HF reception, I use a 30’ ground mounted vertical with about 50 buried radials in different stages of decomposition hihi. For VHF, a roof mounted 2m/70cm SlimJim antenna is used, but I haven’t done much listening in that portion of the spectrum yet except for occasional foray into the aero, 2m ham, NOAA satellite and public service bands. Note that the AirSpy also covers 60 – 260MHz.

An older Dell Inspiron laptop and SDR# are used in conjunction with the AirSpy. For decoding, MultiPSK, FLDigi, MTTY, Yand (for NAVTEX), along with VB cable are the accompanying software to make the digital modes intelligible.

So far I’ve logged a few local LF aeronautical beacons and some DGPS beacons on longwave but will be in a better position to judge its performance when winter sets in. As for the medium (520 – 1710 kHz) wave AM broadcast band, the AirSpy easily brings in both local stations during daytime and distant stations at night with no adjacent channel interference whatsoever. Even low powered community Emergency Alert Stations in the 1600 – 1710 kHz portion of the band can be heard daily from this QTH. A rotatable loop would certainly improve reception though.

As for shortwave listening the AirSpy HF+Discovery is, in my opinion, great for listening to both shortwave broadcasts and utility stations though I tend to concentrate on UTES mostly such as VOLMET, WEFAX, RTTY (the few that remain unencrypted), CW marker stations (e.g. XSG and XSQ from China) NAVTEX (519 kHz), aero/maritime SSB, time signal stations (WWV, CHU) and many of the other esoteric digital utility signals populating the band. As for SW broadcast stations, WRMI, Radio Exterior, RFI, R. Marti, BBC, WWCR and Radio Algerienne, to mention a few have been received. The Frequency Manager (memory storage) in SDR# has quickly filled up with intercepts using the AirSpy.

As a ham and CB operator (yes, the two can mutually coexist in the same human body), I’ve found the AirSpy HF+ Discovery to be a trouper on all the HF ham and CB bands. One of my favorite hangouts is the 28.100 – 28.300 MHz slice of 10m where domestic and international low power CW beacons transmit their callsigns (and at times their grid squares and power output) into the ionosphere and achieve great distances. Recently, beacons from 5, 6 and 7 land in the US along with DX prefixes ED4, PY4 and XE1 were logged. If you’re into 10m FM operation you can also tune the AirSpy to hear local and distant repeaters on 29.62 – 29.68 MHz. When the band is open, .62 and .64 seem to be the most active here in Central NJ.

If you’re a CB (aptly named the Citizen’s Band) op, the AirSpy HF+ Discovery does a stellar job on Channels 1 – 40 which is especially exciting when the band’s open. While domestic (USA) CB’ers are limited to frequencies from 26.965 – 27.405 MHz you’ll nonetheless hear DX ops below our (USA) channel 1 and above channel 40 conversing in French, Spanish and German in LSB/USB. Add to this mix the fact that the FCC dropped the 150 mile limit for US ops a few years back and now the advent of the FM mode operation in the US, you’ll find the AirSpy won’t disappoint. In my opinion the AirSpy HF+Discovery was an excellent choice and I’m more than satisfied with its performance.

In the matter of honesty and full disclosure, I purchased the AirSpy HF+ Discovery completely on my own in an effort to upgrade my station. My choice was based on information gathered from the Internet and YouTube video reviews. The performance of this receiver was based on my experience using the vertical antenna described earlier, the hours spent at my QTH (location) listening to stations of interest to me and my six decades experience as a SWL. No test equipment to assess sensitivity, selectivity or other empirical methods to measure performance was used. That information can be found on the Airspy website. The main purpose of this article was to craft a rudimentary review for those interested with the caveat that reception will vary depending on many factors such as location, antenna, ionospheric conditions, feedline quality, computer/software variations, QRN, QRM, and operator experience. The results presented in this article are typical for my location; others may experience different results. Thanks very much.

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The passing of a compassionate shortwave listener, Agnes Joan Negra

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By Jock Elliott, KB2GOM

I just received this:

Dear Jock:
It is with a heavy heart that I must report that 102 year old, Agnes Joan Negra passed away last Friday, peacefully, and at home. She went into Hospice care about three weeks ago.

We had a private funeral for mom…immediate family only. But I wanted to pass on her obituary which can be found on website:
calhounmaniafuneralhome.com

Thanks for your support of Agnes and her incredible life story, “Waves of Hope”… It is truly appreciated.

We hope this finds you well.
Regards,
Val Negra

Agnes Joan Negra was a shortwave monitor during WWII who sent out more than 300 letters and postcards to families to inform them that their loved ones were captured and still alive.

Click here to check out Waves of Hope on Amazon.

If you would like to know more about how shortwave monitors impacted lives during WWII, check https://swling.com/blog/2022/04/wwii-radio-letters-a-real-life-shortwave-story/ and https://swling.com/blog/2022/04/world-war-ii-radio-letters-a-real-life-shortwave-story-part-ii/ .

As I have said before: And so, dear reader, never belittle your hobby of listening to the airwaves, because you never know when something you heard may be able to offer comfort in times of trouble.

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The two-pocket listening post . . . for when “they” are after you

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By Jock Elliott, KB2GOM

Man on the run thrillers, like The 39 Steps by John Buchan* and Rogue Male by Geoffrey Household hold a special fascination for me. Give me a yarn about someone being pursued by the bad guys, and I am enthralled. (Incidentally, there are a couple of good lists of these thrillers. Here and here).

Sometimes I like to play the mental game of: if I were that guy trying to stay ahead those who wished me evil intent, what radio(s) might I want with me?

The other day I realized I had the perfect combo, a pair of radios that cover a huge swath of spectrum, will fit in a couple of pockets (or one big pocket) and weigh just 14 ounces combined. Further, both will run off ordinary AA batteries, which are widely available.

Candidate number one is the C Crane Skywave SSB, which measures 3 inches by 4.75 inches by 1.1 inches. It receives AM, FM, shortwave (1711-29999 kHz), VHF aviation and NOAA weather radio with alerts. Because it receives single sideband (SSB) on HF frequencies, it can tune in aeronautical, marine and amateur radio stations that transmit in the SSB.

The Skywave SSB comes with a pair of ear buds that fit my ears well and offer pleasing audio. In addition, the SSB comes standard with an auxiliary wire antenna that can be deployed and clipped to the SSB’s whip antenna to boost signal-to-noise. Perhaps most useful for the man on the run, the SSB has excellent “signal seek” functions that can be used on any band. In fact, if you put the radio in SSB mode and activate the signal scan, it will search the ham bands and automatically switch from upper sideband to lower sideband as appropriate.

For the man on the run who can “hole up” for a while, I’ve tried clipping a 50-foot long wire to the SSB’s whip and antenna, and I was amazed at how well it can pull in faint ham signals. It’s the “little radio that could.” About the only thing that I wish I could change on the Skywave SSB is that it mutes between tuning steps when using the tuning knob.

But suppose our man on the run needs to monitor signals above the coverage of the Skywave SSB? Candidate number two is the Icom R6. Measuring just 2.3 inches by 3.4 inches by 1.2 inches, the diminutive R6 covers from 100 kHz to 1309.995 MHz (less cellular and gaps) in AM, FM Narrow and FM wide modes (no SSB). It has 1300 alphanumeric memories, search-and-store capabilities, and rapid scanning of memory channels.

For high stealth, there is a setting that allows the R6 to use the wire that connects headphones or ear buds to the R6 as the antenna instead of the usual antenna. For a non-stealth application, using an aftermarket antenna like the Comet W100RX 25MHz-1300MHz Handheld Scanner Antenna, the R6T does a surprisingly good job of receiving shortwave stations. This antenna has markings on the side so that it can be set to the right length for various frequencies.

As you can see from the photo, the R6 has only a few buttons on its face and two on the side. Every button has multiple functions, and I found trying to program memory channels using the buttons to be a trial. As a result, I can highly recommend the RT Systems cable and programming software for setting up memory channels. In addition, some very useful notes for setting up and using the R6 can be found here: https://forums.radioreference.com/threads/icom-ic-r6-notes.442112/

Finally, I know that there are several tiny ham transceivers that might fill the bill, including the Yaesu VX-6R, although I am not aware of any that can receive single sideband. Besides, if you had the ability to transmit, “they” might be able to direction-find you . . . and we wouldn’t want that, would we?

*For sharp-eyed readers: yes, I know that The 39 Steps is set in a time before radio was widespread, but it is still one of my favorites.

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Giuseppe Demonstrates his homemade “Minimal Long-Distance Dipole”

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

Dear Thomas and Friends of the SWLing Post,

I’m Giuseppe Morlè from Formia, central Italy on the Tyrrhenian Sea.

This time I want to show you 2 QRP connections made with minimal antenna over long distance and very few watts of power…

The antenna is a simple dipole, 5 meters per arm, 1/4 wave for 20 meters, on a bnc / banana socket directly on the Icom 705. You’ll see that the ROS is really optimal.

I wanted to experience this very simple antenna, easy to prepare in this location surrounded by greenery, Monte Orlando Park in Gaeta on my favorite DX bench;
this location is at 120 meters above sea level and facing south / west following the long path. A suitable place for the extreme right made especially for a receiver like the Icom 705– fantastic modulation and without any kind of noise.

In the first video the contact with VK2GJC, Greg from Australia who struggles a little to listen to me but immediately understands my name. As you can hear Greg’s voice is without any imperfection even if his signal is not that high:

In the second video, another link with Australia, VK5AVB, Tony from Kangaroo Island.
Tony had a hard time understanding my name but with the help of Nicola, IU5EYV from Tuscany, in pure Ham Spirit, he finally managed to log me:

As you can see, even with very minimal antennas hoisted on nearby trees, not even high from the ground, you can listen and contact over long distances … that’s why I love this place so much!

Thanks to you all, a cordial greeting from Italy.

Many thanks, once again, Giuseppe for showing us just how much fun we can have by building our own antennas and hopping on the air with very little power. I must say: you certainly play radio in a beautiful part of the world! Thank you!

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Guest commentary: Nothing is so constant as change

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Many thanks to SWLing Post contributor, Jerome van der Linden, who shares the following guest post:

Nothing is so constant as change

by Jerome van der Linden

Those of us who have had an interest in broadcasting over many years realize pretty soon that technology is constantly changing. The following relates to the situation where I live in Australia, but I suspect similar things are occurring in other parts of the world, and serve as a constant reminder that we live in a world of change.

When we were in our teens, we had radios that would tune AM and one or more shortwave bands. Hence many of us first heard interstate medium wave stations, and realised that signals there travelled further during darkness hours. Then we switched to SW1 or SW2 and often heard nothing. But persistence paid off and soon we were listening to stations that were in other countries! And when we connected a long wire to the antenna terminal signals improved dramatically. Wasn’t that amazing?

Somewhere in the 70s (I think) our TV stations brought in colour and that too was an amazing change to experience.

Then – somewhat belatedly for us in Australia – FM radio came along and gee the quality of the audio was outstanding! Even my late father was surprised by the clarity with which he could now listen to classical music on our nationwide dedicated ABC Classic FM station. FM also brought with it the introduction of “Community Radio” stations and in more recent years many other types of broadcasters.

Satellite TV came to us in the form of Foxtel: carrying so many different channels it was bewildering. When I realized that the events of 9-11 were telecast live on BBC World (and others), I too decided we should have Foxtel, as I have always been a “news nerd”.

By the late 1990s – having seen a hey day in probably the 60s and 70s – shortwave listening was rapidly becoming a thing of the past, and only hobbyists listened to SW: I remember being asked by another passenger when I was on a South Pacific cruise, what was that I was listening with out on deck? Was it some kind of computer? No, it was just a Sony SW55, and I was listening to Radio Australia.

Then, probably 5 years ago in Australia DAB+ radio was introduced, and whereas we previously had a choice of perhaps 10 to 15 AM & FM radio stations to tune to, suddenly we had a choice of these same stations on DAB radio (in major cities only), PLUS another 10 or 15! We have a phenomenal choice of what to listen to. From a technical view it was amazing to think that all the signals were coming from only one or two transmitters. For those of us with some technical interest it was for a while inconceivable that each station would not have its own transmitter.

Meanwhile, our TV systems have also become digitized in the last couple of years. Not just do we have perhaps three different channels for each commercial network, so 3 commercial networks are now providing probably 9 different programs. On top of that the Government broadcasters (ABC & SBS) have provided not just at least 3 TV channels each, but each of their numerous radio services is now also available on every TV set (eg BBC World Service is available 24/7).

About the same time, with higher internet speeds (ie better data transfers) being available, TV services and radio services are increasingly being streamed into our homes and to our mobile devices, with radio Apps promising they’re “free”, when in fact they do incur a data transfer impact/cost in whatever Internet plan one may have available. Many of the older generation probably don’t even realize what streaming video or sound means, but I think the younger generation is catching on.

Now, to my horror, my favourite DAB music station (“Buddha”) has been making announcements on air saying that the DAB service will be terminated from September 1st, and if I want to continue listening, I must tune in using that Company’s own “LiSTNR” app! Does this mean that listening to what comes over the ether will be a thing of the past? Will we be obliged to pay $x per annum to use a company’s streaming app just to be able to listen to their programs? Whatever is the world coming to?

Our country is, I suspect, very well catered for in terms of media services, and I wonder if we’ve done that too well. I also fear though, that those of us trying to push for reintroduction of shortwave services for remote Northern Territory areas (where streaming apps are a non sense), and for Australia to again broadcast into Pacific territories, may be fighting an uphill battle.

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

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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 SWLing.net 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 SWLing.com message board: https://swling.net/viewtopic.php?t=55

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.

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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Matt’s 2022 Portable Loop Antenna Shootout

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Many thanks to SWLing Post contributor, Matt Blaze, for the following guest post:

Matt’s 2022 Portable Loop Antenna Shootout

by Matt Blaze, WB2SRI

Followers of this blog may be familiar with my “shortwave radio shootouts” that I post from time to time. The idea is to compare how well different radios demodulate the exact same signal. Basically, I take a bunch of radios, hook them up to the same antenna via an RF distribution amplifier, tune the radios to some distant signal, and record the audio output from them simultaneously. Sometimes that kind of comparison can be more revealing of actual real-world performance than lab measurements or technical specifications.

The other day, I decided to do the same thing, but for antennas instead of radios. Essentially, I inverted the setup. Instead of hooking up different radios to the same antenna, I hooked up identical radios to different portable antennas and recorded them demodulating the same signals at the same time.

In this first of perhaps a series of these antenna shootouts, I wanted to compare three portable amplified magnetic loop antennas. When I say “portable” here, I mean broadband antennas that can pack reasonable compactly for travel and that can be set up and broken down easily for use “on location”, say on a picnic table or hotel balcony, or perhaps installed temporarily on a roof, without too much fuss.

The antennas are:

– The Wellbrook FLX1530LN with a 1 meter diameter loop of LMR400 coax. This is my “standard” portable antenna (I use a telescoping broom handle for the support; I wrote about it here as the “signal sweeper” last year). Excellent performance, but on the bulky side for travel. Performs well from LW through HF. Not cheap, at about USD 225 including shipping for the amplifier and power injector, but not including the loop, mounting hardware, or feedline.

– The Wellbrook FLX1530LN with a 0.5 meter diameter loop of RG142 (a stiff “aircraft grade” version of RG58 that holds it shape well at this size). I used some 1/2 inch PVC pipe as the vertical support. Because of the smaller diameter loop and thinner coax, it packs down to a much smaller and lighter package than the 1 meter LMR400 version.

– The K-180WLA, an inexpensive (about USD 60) 0.5 meter loop from China, sold on eBay and Amazon. The loop is steel wire (which can be wound down to a small diameter for transport), and the kit includes everything you need, including a rechargeable power injector. (However, the power injector uses a noisy voltage booster, so I substituted my own bias-T injector for these experiments). Ostensibly covers LW through VHF, but the low end coverage is, shall we say, somewhat aspirational, as you will see.

– I also recorded, for comparison, the built-in ferrite bar (for LW/MW) and whip antenna (for HF) of the receiver.

This is, of course, only a small sampling of portable loop antennas, both commercial and homebrew. But I wanted to start with what I had on hand and with what meets my own needs. (I omitted from consideration loops that require tuning, since I want to be able to install the antenna without needing access to it every time I change frequency).

For each signal captured, I oriented and positioned each antennas to maximize signal quality, taking care to move them away from each other and interfering metal objects. So you’re hearing (approximately) the best each antenna had to offer (on my roof under suboptimal band conditions).

The receivers I used were four Sangean ATS-909×2 portable LW/MW/SW/FM/Air radios. I believe this to be the best currently available (relatively inexpensive) portable shortwave receiver on the market. It has excellent performance (and is admirably resistant to overload and intermod when used with an active antenna). It lacks a sync mode, but that’s rarely implemented well on portable radios anyway. As a practical matter, it has a good line-level output jack, and I already happened to own four of them.

As in my other shootouts, for each signal, there are a total of five recordings: a monoaural recording of the audio from each of the four antennas, plus a narrated stereo recording comparing a reference (the 1M Wellbrook) on the Left channel with each of the other antennas in succession on the Right channel. The stereo recording is intended as a quick overview, but it will only make sense if you listen in stereo, preferably with good headphones. (You can switch the earcups to get a quick comparison as you listen.)

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