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Many thanks to SWLing Post contributor, TomL, who shares the following guest post:
Comb Stereo on Shortwave
by TomL
Comb Stereo is an old technique being implemented over shortwave by the main sound engineer (Daz) at Radio Northern Europe International (RNEI). It ONLY works on Comb Stereo broadcasts which currently are RNEI, This Is A Music Show (WRMI), and one of the KBC broadcasts. It works in real-time or for SDR recorded files, too. It does NOT need a special HD/DAB+ radio.
A number of pluses for Comb Stereo on shortwave compared to digital:
“The bandwidth is the same as mono – So the SNR should be about the same as mono.
Selective fading doesn’t affect the comb bands much, so the balance is largely unaffected by selective fading notches.
The Comb Stereo artifacts are much like typical music effects of echo, chorus, fast reverb or room reflections.”
An enhanced version is broadcast on WRMI for the RNEI time slot on Thursday morning (01:00 UTC) on 5850 kHz. It sounds very good and is not a pseudo-stereo like in my previous article, Music on Shortwave. For one thing, pseudo stereo is not real two-channel encoding and shifts vocals to one side, depending on which channels are chosen for high and low filters, which might get annoying after awhile. What seems amazing to me is that I have been able apply some minor noise reduction in Audacity and the Comb Stereo stays perfectly intact. It also still works after converting the WAV file to MP3 and sounds much like a regular FM broadcast. Furthermore, it does not require a special patented transmitter or receiver chip. It is compatible with regular mono transmitters.
If you want to try it, go to the RNEI web site; download and install the two files listed (VB Audio Cable and CombStereo Pedalboard x64):
It is slightly tricky to setup and use or you will not hear anything (most Windows systems default to 48000 Hz these days). Right-click on the lower-right taskbar Sounds settings. Make sure to setup Properties – Advanced in both the VB-Audio Virtual Cable (Playback and Recording) and your output speakers (Playback) to 24-bit 44100 Hz processing.
Now run the app Pedalboard BAT file which corresponds to the broadcast you recorded (in this example “Start Comb Stereo for WRMI.bat”). Set the Options – Audio Settings:
Since the VB-Audio Virtual Cable takes over your volume output, adjust the volume of your Speakers in Windows’ Sounds – Levels (or you can adjust the volume in the sound player you are using, too):
Play the mono WAV or MP3 file and you should be hearing stereo!
When you are done, close Pedalboard2 and then disable the VB-Audio Virtual Cable for Playback and Recording to get your Sounds back to normal:
I cannot demonstrate what it sounds like unless you have the VB-Audio Virtual Cable and the Comb Stereo app setup and working properly. Here are snippets from recent RNEI broadcasts captured by my noisy porch antenna:
What is nice is that I can create a space-saving MP3 mono file and this setup will decode the stereo when run from the computer (sounds really nice on a stereo system with a subwoofer). Unlike digital, this analog-friendly stereo seems mostly immune to fading, has a minimum of digital artifacts, and will not go silent and “drop out” like digital does for long, annoying periods of time. It is not perfect stereo but audio players with features like Stereo Widener or Windows Sonic for Headphones can overcome some limitations. Perhaps content providers should consider Comb Stereo for all their shortwave radio shows since it is perfectly compatible with mono AM transmissions!
A few weeks ago, Chameleon Antenna sent me a pre-production model of their new wideband magnetic loop antenna called the Chameleon CHA RXL.
I’ve evaluated and reviewed a number of Chameleon’s ham radio antennas (primarily on QRPer.com). I find that the quality of their products are second to none. Price-wise, they tend to be at the top of the market, but keep in mind they machine and manufacture all of their antennas here in the US and they’re incredibly rugged; indeed, military-grade. And in the spirit of full disclosure, I’m proud Chameleon has been a sponsor the SWLing Post and QRPer.com since last year. My sponsors are by invite only and focus on companies I trust with our radio community’s business.
When Chameleon shipped the CHA RXL to me, it wasn’t from their factory, it was directly from the field: Fort Irwin, to be exact.
(Source: NTC Operations Group, Ft. Irwin)
This CHA RXL sample had been used by NTC Operations Group Fort Irwin (who, incidentally, won QRPX this year–click here to read the PDF report).
I was told that the condition of the antenna could be very rough after the QRPX because it had essentially been sandblasted in the desert winds. I was also told that someone accidently transmitted 5 watts into it at some point but it didn’t seem to harm it (for the record, like all amplified receive-only loops, it’s not designed to take RF).
Tony (W0NTC), who was one of the Ft. Irwin radio ops, sent me this note as he dropped off the shipment at Fort Irwin’s FedEx:
“Had a blast with [the CHA RXL], and it was absolutely critical while I was operating in the Army HF Low Power Competition (think tons of high powered MARS stations piling up and drowning out the 20W or less competitors). It absolutely crushed some localized RFI from a huge building I operated behind, and the receive on it I can only describe as “layered” in that I could hear stations somewhat clearer than usual if they transmitted simultaneously. Receiver I used was the IC-705 with default Auto Notch and Noise Reduction.”
Tony volunteered all of this info–I never asked him how it performed.
A few days later, I wasn’t sure what to expect when I opened the box although I knew that my operating locations were nowhere near as cool as its position next to a Humvee at Fort Irwin in the photo above!
I pulled the CHA RXL out of the box and it looked cosmetically flawless to me.
Frankly, there’s not a lot to get damaged. The 36 inch diameter loop is made of rigid aluminum and has a Navy gray powder coating. The preamplifier unit is completely sealed and made of a high-impact plastic/PVC type material. The steel loop is attached to the preamplifier loop flanges with wing nut connectors.
The only potentially vulnerable part of the antenna system is the Bias-T box which would normally be located in your shack close to your receiver.
If I mounted the CHA RXL permanently outdoors, I would use Coax Seal around the BNC connection point, of course.
Although the CHA RXL has a supplied mounting bracket for permanent installations, I love the fact that the preamp box has a 1/4” x 20 threaded camera socket on the bottom. This makes for a brilliant portable loop because it can so easily be mounted on a standard heavier-weight tripod! All antenna manufacturers should give us tripod mount options when possible.
On the air
One of the reasons amplified receive loop antennas have become so incredibly popular over the past couple of decades is because they do an amazing job mitigating radio frequency interference (RFI) a.k.a. “QRM.” If you live in a neighborhood with significant radio interference, you really should consider some form of loop in your antenna arsenal.
Ironically, at home, I live in pretty much an RFI-free zone. I’m surrounded by tens of thousands of acres of national forest, so I’ve only used amplified loop antennas in the past for mediumwave DXing–mainly, when I wanted to take advantage of their amazing ability to null out unwanted signals.
Many years ago, I purchased a Pixel Loop Pro antenna (now under a different name via DX Engineering), mounted it outside where it lasted almost a year before a bear decided to pull it down and chew through the coaxial feedline. He/she did so with enough energy that it ripped down the loop and damaged the connector end of the Pixel’s pre-amp. This all happened when our family was travelling for two months in Canada. Why bear, why?!? But I digress…
The CHA RXL version I was shipped has one single rigid loop–the “EU” version’s loop comes in two pieces (for easier shipping/transport)–but I had no problem fitting the entire assembled loop in the back seat of my Subaru or my truck (as long as no one was sitting back there at the time). If you plan to travel with your loop a lot, consider the “EU” version!
I’ve taken the CHA RXL to my parent’s home a couple of times and enjoyed doing a little mediumwave and shortwave listening. Inside the house, the loop would attenuate RFI nicely, but when outside it would all but eliminate many sources of RFI.
At their house, I primarily used my Icom IC-705 for cruising the bands (being careful, of course, to disengage the transmit function).
Listening time in my hometown, though, was very limited. Since the CHA RXL is so portable, I decided to set it up at home on our porch for a few days, giving me an opportunity to test both the Sangean ATS-909X2 and Tecsun H-501x with an external antenna.
I’ve especially appreciated using the CHA RXL on mediumwave. Even from our screened-in porch, I can rotate the loop and use its excellent nulling properties to pick out multiple station IDs on crowded frequencies.
I’ve spent time on shortwave, too, and found that it certainly gave these two portables a signal boost.
In fact, it was by using the CHA RXL that I discovered the audio level difference between AM and SSB on my ATS-909X2 is very minimal when an external antenna is connected.
I’m sure you’ll hear the CHA RXL in action when I post audio clips and recordings in upcoming reviews.
Summary
If I owned a CHA RXL loop, one of the first things I’d do is build a power cord for it with an in-line fuse and terminated with an Anderson Powerpole connector. Since the operating voltage of the Bias-T is 12-14 VDC, it would pair perfectly with one of my Bioenno LiFePo4 batteries, offering a power source with longevity in the field–ideal for a group LW/MW/SWL DXpedition.
It’s difficult for me to truly comment on the loop’s performance because I don’t have another loop at present for comparison. I can say that it’s amazing on mediumwave, where I’ve spent much of my listening time this past week. I believe shortwave reception has been at least on par with my former Pixel Loop, if not better. It’s hard to say, in truth, because propagation conditions have been so poor lately. The CHA RXL loop does effectively mitigate noise!
I’m not sure if the CHA RXL is currently on backorder or not, but I would suggest you check out the product page on Chameleon’s website and possibly contact them if you’re interested. They’ve a number of options and accessories to consider.
One thing for sure: this must be one of the most rugged and durable RX loop antennas on the market. In addition, that Navy gray powder coating helps this rigid aluminum loop disappear against the sky. I believe you could strategically mount this loop and the friendly neighborhood association may never notice–it’s pretty stealthy. Speaking of which…
Josh’s CHA RXL install and demo video
Josh over at Ham Radio Crash Course recently installed a CHA RXL on his house and tested it on several bands, comparing it with a number of his external antennas:
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’sRadio Waves, a collection of links to interesting stories making waves in the world of radio. Enjoy!
Many thanks to SWLing Post contributors Paul, Richard Langley, Troy Riedel, and the Southgate ARC for the following tips:
Solar-powered portable radios that put audio quality second are nothing new. But a solar-powered portable radio that sounds as good as a non-solar high-fidelity radio: This is worth talking about.
The new CCRadio Solar from C.Crane fits this double-barreled description. With its generous top-mounted solar panel (3.75 by 1.5 inches) plus back-mounted generator crank for recharging its Lithium-Ion battery pack, this is a radio for blackouts and other emergency situations.
After an initial conditioning charge-up of the Lithium-Ion battery from a 5V DC adaptor, just leave it in a sunny window, and the radio is always ready to go.
In non-emergency situations, the CCRadio Solar can be powered with three AA batteries or a 5V DC charger plugged into its micro-USB port.[…]
The U.S. Congress is reportedly taking steps to officially recognize the important contributions made by amateur radio operators.
According to an article on the website of the ARRL, Congresswoman Debbie Lesko (AZ) has introduced a bipartisan resolution to designate April 18, 2022 as National Amateur Radio Operators Day. April 18th is the anniversary of the founding of the International Amateur Radio Union (IARU) which was established in 1925.[…]
YOUR GRANDPARENTS’ ancient transistor radio might still turn on and tune in to stations broadcasting conventional AM or FM signals. But in this Internet age, a blizzard of content is available from sources accessible only via the Web. What’s more, instead of speakers that flood a room with sound, we’ve grown accustomed to personal listening using earbuds and headphones. Now engineers like Guillaume Alday, founder of Les Doyens in Bordeaux, France, have come to the radio’s rescue. Alday keeps old-school radios from slipping into obsolescence by retrofitting their innards with components that transform them into Wi-Fi- and Bluetooth- enabled devices.[…]
The BBC reports the first message sent back to Britain by a ‘trailblazing’ special agent in World War Two has been commemorated, 80 years on, by radio amateurs using GB1SOE
Georges Begue, of the Special Operations Executive, was parachuted into occupied France in 1941 to set up wireless communications with the UK.
Amateur radio enthusiasts have marked his achievement by sending and receiving messages at Bletchley Park.
On Thursday and Friday May 6-7, Milton Keynes Amateur Radio Society is using replica equipment to transmit Morse code messages from the National Museum of Computing at Bletchley to fellow radio enthusiasts in central France, stationed less than a mile from where Begue landed.
Turkey celebrated Radio Day on the 94th anniversary of the start of radio broadcasting in the country.
“Radio broadcasting in Turkey started 94 years ago today with the first announcement,” Turkey’s Presidential Communication Director Fahrettin Altun wrote on Twitter.
“Our radios, which have been working devotedly to bring our beloved nation together with the truth for years, have become one of the most important parts of our lives,” he added.
Altun also congratulated all radio workers on Radio Day too.
Türkiye Radyolar? (Radios of Turkey) has started first radio test broadcasts in 1926, with a studio built in Istanbul. The first radio broadcast in the country, however, began on May 6, 1927.[…]
Many thanks to SWLing Post contributor, Grant Porter, who notes that Ham Radio Outlet has the Eton/Grundig AN200 loop antenna on a closeout sale for $15.00.
As Grant notes, this is an especially great deal if you live near an HRO retails store.
Many thanks to SWLing Post contributor, Gary DeBock, who shares his extensive 2021 Ultralight Radio Shootout.
This is truly a deep dive featuring five popular ultralight portable radios and examining mediumwave, shortwave, FM, and AIR Band performance.
The review is an amazing 40 pages long! In order to display the entire review, click on the “Continue reading” link below.
2021 Ultralight Radio Shootout
Five Hot Little Portables Brighten Up the Pandemic
By Gary DeBock, Puyallup, WA, USA April 2021
Introduction The challenges and thrills of DXing with pocket radios have not only survived but thrived since the Ultralight Radio Boom in early 2008, resulting in a worldwide spread of the hobby niche group. Based upon the essential concepts of DXing skill, propagation knowledge and perseverance, the human factor is critical for success in pocket radio DXing, unlike with computer-controlled listening. The hobbyist either sinks or swims according to his own personal choices of DXing times, frequencies and recording decisions during limited propagation openings—all with the added challenge of depending on very basic equipment. DXing success or failure has never been more personal… but on the rare occasions when legendary DX is tracked down despite all of the multiple challenges, the thrill of success is truly exceptional—and based entirely upon one’s own DXing skill.
Ultralight Radio DXing has inspired spinoff fascination not only with portable antennas like the new Ferrite Sleeve Loops (FSL’s) but also with overseas travel DXing, enhanced transoceanic propagation at challenging sites like ocean side cliffs and Alaskan snowfields, as well as at isolated islands far out into the ocean. The extreme portability of advanced pocket radios and FSL antennas has truly allowed hobbyists to “go where no DXer has gone before,” experiencing breakthrough radio propagation, astonishing antenna performance and unforgettable hobby thrills. Among the radio hobby groups of 2021 it is continuing to be one of the most innovative and vibrant segments of the entire community.
The portable radio manufacturing industry has changed pretty dramatically over the past few years as much of the advanced technology used by foreign companies in their radio factories in China has been “appropriated” (to use a generous term) by new Chinese competitors. Without getting into the political ramifications of such behavior the obvious fact in the 2021 portable radio market is that all of the top competitors in this Shootout come from factories in China, and four of the five have Chinese name brands. For those who feel uneasy about this rampant copying of foreign technology the American-designed C. Crane Skywave is still available, although even it is still manufactured in Shenzhen, China—the nerve center of such copying.
Prior to purchasing any of these portables a DXer should assess his own hobby goals, especially whether transoceanic DXing will be part of the mission– in which case a full range of DSP filtering options is essential. Two of the China-brand models use only rechargeable 3.7v lithium type batteries with limited run time, which may not be a good choice for DXers who need long endurance out in the field. A hobbyist should also decide whether a strong manufacturer’s warranty is important. Quality control in some Chinese factories has been lacking, and some of the China-brand radio sellers offer only exchanges—after you pay to ship the defective model back to China. Purchasers should not assume that Western concepts of reliability and refunds apply in China, because in many cases they do not. When purchasing these radios a DXer should try to purchase through a reputable seller offering a meaningful warranty—preferably in their own home country.
One of the unique advantages of Ultralight Radio DXing is the opportunity to sample the latest in innovative technology at a very reasonable cost—and the five pocket radio models chosen for this review include some second-generation DSP chip models with astonishing capabilities. Whether your interest is in domestic or split-frequency AM-DXing, FM, Longwave or Shortwave, the pocket radio manufacturers have designed a breakthrough model for you—and you can try out any (or all) of them at a cost far less than that of a single table receiver. So get ready for some exciting introductions… and an even more exciting four band DXing competition!
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’sRadio Waves, a collection of links to interesting stories making waves in the world of radio. Enjoy!
Many thanks to SWLing Post contributors Paul L, Pete Eaton, David Iurescia, and Troy Riedel for the following tips:
The PIRATE Act was signed into law more than a year ago, but the rules governing increased fines for unlicensed broadcasting are about to go into effect on April 26. The Act is intended to give the FCC additional tools for tamping down pirate radio activity in hot beds like Boston and Brooklyn, NY, but there are reasons to be skeptical.
Brooklyn-based writer, post-production mixer and field recordist David Goren joins to help us tease out the real-world implications. Goren is also the creator of the Brooklyn Pirate Radio Sound Map and has been monitoring and recording unlicensed radio activity in the borough for decades.
Also joining the show is Dr. Christopher Terry from the University of Minnesota. A professor of media law, he helps illuminate some of the legal and bureaucratic elements that complicate the Commission’s efforts. He also catches us up on the latest development in the battle over media ownership rules, with the Supreme Court issuing a narrow unanimous ruling in favor of the FCC’s most recent changes, but not quite addressing the decades-long gridlock in that policy area.
The disappearance of Malaysia Airlines flight MH370 after an unexplained course change sent it flying south over the Indian Ocean in March 2014 still holds the mystery of the wreck’s final location. There have been a variety of efforts to narrow down a possible search area over the years, and now we have news of a further angle from an unexpected source. It’s possible that the aircraft’s path could show up in radio scatter detectable as anomalously long-distance contacts using the amateur radio WSPR protocol.
WSPR is a low-power amateur radio mode designed to probe and record the radio propagation capabilities of the atmosphere. Transmit beacons and receiving stations run continuously, and all contacts however fleeting are recorded to an online database. This can be mined by researchers with an interest in the atmosphere, but in this case it might also provide clues to the missing airliner’s flightpath. By searching for anomalously long-distance WSPR contacts whose path crosses the expected position of MH370 it’s possible to spot moments when the aircraft formed a reflector for the radio waves.[…]
His provocative “Radio Unnameable,” long a staple of the New York station WBAI, offered a home on the FM dial to everyone from Abbie Hoffman to Tiny Tim.
Bob Fass, who for more than 50 years hosted an anarchic and influential radio show on New York’s countercultural FM station WBAI that mixed political conversation, avant-garde music, serendipitous encounters and outright agitation, died on Saturday in Monroe, N.C., where he lived in recent years. He was 87.
His wife, Lynnie Tofte, said he had been hospitalized with Covid 19 earlier in the month, but he died of congestive heart failure.
The Dicastery for Communication marks the 30th International Marconi Day with a celebration at Vatican Radio’s historic broadcast station outside Rome.
International Marconi Day is held every year on the Saturday closest to the birthday of the inventor of the radio, Guglielmo Marconi, on 25 April 1874.
This year’s commemoration fell a day earlier, and saw dozens of radio stations exchange messages, including Vatican Radio, which Marconi himself helped found in 1931.
The 30th iteration of Marconi Day was celebrated at Vatican Radio’s broadcast center at Santa Maria di Galeria, outside Rome.
Day for those who love radio
According to Dr. Paolo Ruffini, the Prefect of the Dicastery for Communication, it was “a day spent in a family spirit” for those who love the Radio and the man who invented it.
He noted that the broadcast station forms both the center and periphery of Vatican Radio, since it is the place where radio waves are emitted which carry the Gospel and the words of the Popes throughout the world.
Marconi’s favorite Radio
The 30th Marconi Day falls within the 90th anniversary year of the founding of Vatican Radio.
The great Italian inventor’s daughter, Princess Elettra Marconi, who was present for the celebration, recalled that the station was her father’s favorite, though he had founded several others.[…]
Many thanks to SWLing Post contributor, Bill Hemphill (WD9EQD), who writes:
