Author Archives: Thomas

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.

Dan spots an ultra-rare National HRO-600 on Buyee

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Many thanks to SWLing Post contributor, Dan Robinson, who writes:

Wow. Appearing on the Japan Buyer site is one of the top rarities, the National HRO-600
https://buyee.jp/item/yahoo/auction/m1066450646

As veteran SWLs may recall, the HRO-600 was pictured in the old Communications Handbook receiver sections.

The radio sold for the then astronomical price of $5600 US. Produced just as National was declaring bankruptcy, the 600 was the final radio from the company.

The last time one of these appeared on the used market was in 2015 and the best writeup on the receiver can be found here.

The condition if this HRO-600 is poor so it may not be salvageable, but it’s nice to see another one show up on the used market since supposedly only 200 or so were made.

Thank you for the tip, Dan! I hope someone grabs this HRO-600 and does a proper restoration job!

Andy finds his late model PL-660 lacking compared with an earlier model

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The Tecsun PL-660 (left) next to the XHDATA D-808 (right)

Many thanks to SWLing Post contributor, Andy, who writes:

Hi Tom,

I wonder if any of your readers has noticed anything with later model PL-660s.

My old PL-660 met with an accident recently (purchased about 2015?).

I bought a new one and was disappointed by what appears to be
a difference with the narrow and wide filter.

My old version seemed to work well, with 3kHz and about 6kHz
widths as one would expect.

The new one is a disaster, you seem to get 3kHz and 18kHz widths roughly
resulting in poor performance, especially on local AM stations.

It’s like the same station appears twice.

Also the filter is not symmetrical.

It’s all on the HF side of the signal and it’s awful.

The older model centred the correct bandwidths properly.

I’ve tried to do a bit of research, not much really but the little info that I have found appears to show that others have the same problem.

It makes the use of the wide filter in any mode useless.

I’m gonna send mine back.

73 de Andy G0FTD

Thanks for sharing this, Andy. I haven’t purchased a PL-660 in ages–in fact, I gave mine to a friend interested in shortwave a few years ago. I still use my PL-680 regularly. I suppose it’s possible you might have received a lemon; this isn’t uncommon as quality control varies with production batches.

SWLing Post readers: If you have noticed these symptoms–especially an abnormally wide filter width–with your late model PL-660, please comment.

Mark explores North Korean DRM broadcasts over shortwave

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In the last issue of Radio Waves, we featured an article by Hans Johnson at Red Tech about DRM broadcasts originating in North Korea. This caused me to question exactly what these DRM broadcasts were (Voice of Korea?) and why they’ve chosen to use DRM as the mode.

Of course, who really knows? North Korea isn’t public about any of their activities, so we rely on information from enthusiasts who have taken it upon themselves to investigate and confirm. Johnson assumed, “The most likely use [of DRM] would be as an audio feed to other stations and sites.” He used Radio New Zealand’s DRM service as an example, but I felt this to be unlikely with North Korea who doesn’t seem to use FM, MW, or shortwave relay sites in other parts of the world.

Fortunately, our friend Mark Fahey is an expert on North Korean media, broadcasts, and propaganda. Mark is the author and curator of the dynamic Behind The Curtain project.

I reached out to Mark via text message regarding North Korea’s use of DRM. Here’s what Mark shared with me earlier this week. This roughly follows the string of messages we exchanged.

Mark writes:

[October 3, 2022] I have been turning into the North Korean DRM today on the new reported frequency in the [Red Tech] magazine: 6140kHz, though it’s not VOK, it’s a relay of 819kHz Pyongyang.

This service is called KCBS – Korean Central Broadcasting Service – it’s the main domestic service that is available on MW (a few FM outlets) and domestic SW across North Korea.

I will grab an audio ID off DRM for you at the top of the next hour – 0100 UTC. The DRM broadcast is only running one audio stream. It’s ACC audio 14.56kbps. As for purpose, maybe to feed the national AM relays, but also could be for North Korean ships, etc.

The other DRM frequency of 3205kHz is not on the air at the moment. I will check for it over the next 24hrs etc.

I just recorded the top of the hour. It was going in and out of DRM sync – I will send it now. I will grab a better sample tonight when there is a darkness path. The sun is well up in Pyongyang & Sydney at the moment (Noon Sydney – 10AM North Korea). Here is the Top Of The Hour ID from 10 minutes ago…

KCBS 6140 kHz (October 3, 2022)

I will record the station opening as well tomorrow morning – this domestic service also has an interval signal (the same tune as VOK–the first bars of “The Song (Hymn) of Kim Il Sung”). The opening is at 2000 UTC.

[October 4, 2022] OK here you go: both audio files (one from 6140kHz and the other from 3205kHz) are just from minutes ago as KCBS Pyongyang signed on. The signals go in and out of DRM lock here and this morning 3205kHz was the better–displayed at SNR at 13dB but still the DRM signal was breaking up.

Both DRM transmitters are running the same program: the main MW national service as heard on 819kHz in Pyongyang.

So I’m sure this DRM has nothing to do with the Voice Of Korea and is for domestic purposes.

I actually do not think it has anything to do with feeding remote transmitters as the DPRK has fibre and microwave links already in place for that purpose. I myself think it’s more likely intended for North Korean fishing vessels, navy, merchant shipping etc. But of course, nobody truly knows!

KCBS 3205 kHz (October 4, 2022)

KCBS 6140 kHz (October 4, 2022)

Thank you so much for your recordings and insight, Mark!

As I mentioned, Mark has a massive DPRK audio repository on his website Behind The Curtain. These are recordings you simply can’t find anywhere else, including hours of pristine Pyongyang FM recorded on a CC-Crane Witness Mark personally smuggled into Pyongyang.

In fact, the above photo is the CC Witness in Mark’s hand overlooking central Pyongyang.

Mark told me that the CC Witness was ideal–he used it on a number of content gathering trips to North Korea as it resembled an MP3 player or dictation recorder rather than a radio. Since it wasn’t suspected as being a radio recording device, it passed through the North Korean border each time without incident.

It’s an understatement to say that Mark took a number of risks to gather North Korean media from “Behind the Curtain.” Thank you, again, Mark, for sharing this info about DPRK DRM broadcasts.

Visit Behind the Curtain

Check out numerous recordings from North Korea in Mark’s archive.

Radio Waves: WRMI Damaged by Ian, VOK Podcast, and North Korea Increases DRM

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Radio Waves: Stories Making Waves in the World of Radio

Welcome to the SWLing Post’s Radio Waves, a collection of links to interesting stories making waves in the world of radio. Enjoy!

Shortwave Station WRMI Damaged by Ian (Radio World)

The vast Okeechobee, Fla., antenna farm of privately-owned WRMI, which transmits programming to the world via shortwave radio, was hit hard by Hurricane Ian.

WRMI has 14 transmitters and 23 antenna systems. “We had winds up around 100 miles per hour, and that did a real number on our antenna field,” said Jeff White, general manager of WRMI.

“So far we have three antennas that are probably destroyed beyond repair: one to Europe, one to Africa and one to Central America and the South Pacific.”

As pressing as rebuilding these three antennas is for WRMI, “The biggest job we have at the moment is putting back up dozens of telephone poles that carry the transmission lines from the transmitter building to the antennas,” said White. [Continue read at Radio World…]

>>–Click here to donate to WRMI’s Hurricane Relief Fund.–<<

Voice of Korea programming available as a podcast

Many thanks to SWLing Post contributor, Alex, who notes that some of VOK’s language services are now available in podcast form. If you wish to hear some old school propaganda in high fidelity, this is a good way to do so: check it out on Castbox.

North Korea Doubles Digital Radio Output (Red Tech)

After years of experimentation, the famously secretive nation has switched on another DRM shortwave transmitter. The big question: Why?

Click here to read the full story in Red Tech’s latest issue (see page 12) or click here for page 12 only.

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Alex shares details about the latest Belka portable and upgrades

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After posting information about the new Belka upgrades yesterday, Belka designer, Aleksandr Buevskiy, reached out to me and shared the following details and clarification about the latest design:

I would like to share some more details/photos about Belka so that there is clear understanding of what features the new version has.

First, regarding its name. Now there’s no “DX”, “DSP” or something else. Belka is just named “Belka”. As simple as that 🙂

Second, frequency range was extended with the same parameters and performance. It’s now 0,1-31 MHz.

In previous versions there were 32 memory cells, we’ve now added a few more – 36 is exact number now to be precise.

One more thing about memory cells is that now there is a possibility to listen to memory cells before loading. See attached how it looks like (I’ve added video illustrating memory cells listening just because there were questions).

I also attach several photos of new version and add block diagram. You’ll find attached also PCB photo of new version:

Cheers,
Alex
EU1ME

Thank you for sharing all of this detail, Alex. I believe your new Belka will be a hit! I’m sure readers reach out with their reviews and we will share them here on the SWLing Post!

Click here to check out the new Belka.

Ham & HiFi offers readers discounts on the original CHA-RXL mag loop antenna

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I received the following message/announcement below from Ethan at Ham & HiFi regarding some inventory they have of the original Chameleon CHA RXL loop antenna. This antenna is the one Dan Robinson originally reviewed and Josh at Ham Radio Crash Course demonstrated in a video.

Note that they’re offering this deal as an exclusive to SWLing Post readers and also volunteered to give back a modest percentage of the sales to the SWLing Post coffee fund. They would obviously like to move this inventory, hence the discounts, etc.

This antenna would benefit from a BCI filter especially if you live near a broadcast station; something like this one (you would need adapters for SMAs). As Ethan notes this loop has been replaced by the CHA RXL-Pro at Chameleon (click here to read Dan’s review of the new loop).

Many thanks to Ethan for sharing the following announcement/promotion:

Here’s a great chance to pick up a Chameleon RXL LOOP antenna at an unbeatable price! This broad-banded receiving antenna is perfect for shortwave listening and other applications as it covers 137.5KHz through 30.0MHz. The only difference between this antenna and Chameleon’s new RXL PRO is the preamp design, otherwise its construction is identical.

Ham & HiFi is making these RXL LOOP antennas available to SWLing.com subscribers for $320 + shipping. The new RXL PRO retails for $525, so this is a great chance to save some money! Again, this price is only available to SWLing Post subscribers, so please be sure to reference this promotion.

Place your order by contacting Ethan at 866-988-0073 or email at [email protected].