Category Archives: Mediumwave

13dka Reviews: The new 2022 “Belka” (generation 3) general coverage receiver

The new 2022 “Belka” (generation 3) general coverage receiver

by 13dka

Since its introduction in 2019, the super-tiny Belka (back then called “Belka DSP”) shortwave receiver sure gained an enthusiastic followership among SWLs and hams. The main reason for this is certainly the way how the Belka is incredibly small yet playing in a different league than the various consumer grade, Chinese mass-production radios, particularly the DSP-based ultraportables: The Belka is an all-mode shortwave communications receiver with a completely different (direct conversion SDR) architecture, developed and produced by a radio enthusiast (Alex, EU1ME) in a small mom&pop shop in Belarus.

In case you’ve never heard about it amidst all the buzz about more popular brands, here’s the skinny:

The Belka offers true allmode (including NFM and CW) reception with a proper 400 Hz CW filter and individual settings for the low and high filter slopes for AM, FM and SSB. It has an AM sync detector and comes with a 0.5ppm TCXO-controlled local oscillator for absolutely spot-on, calibration-free frequency precision and stability, which makes SSB or ECSS reception of broadcast stations a pure joy. The second iteration “Belka DX” brought a slightly extended coverage down to 1.5 MHz and an I/Q output for panadapter display and/or processing via your favorite SDR software.

All Belkas are quiet and very sensitive radios with a surprisingly robust front end, the filters are better and its AGC works like you’d expect it from a communications receiver, without the artifacts and distortion the DSP radios are infamous for, and of course smooth, non-“muting” tuning in variable steps down to 10Hz.

The Belkas have no built-in speaker (available as option tho) but really excellent audio on headphones and external speakers and they actually give my Icom IC-705 a run for its money in terms of reception quality, and they do that for up to 24 hours on a single charge of the internal Li-Ion battery. This stunning feature set is crowned by the best performance on a telescopic whip antenna ever – the Belkas have a high-impedance (>10 kOhm) antenna input optimized for this whip and taking it on a walk is (really!) like having a big rig with a big antenna in tow…

Despite all this goodness setting the Belka(s) quite fundamentally apart from most (if not all) current and former, even much higher priced portables and simultaneously putting it solidly into pricey tabletop territory, it hasn’t put Tecsun et al out of business for a couple of reasons: One reason is that it can only be obtained from Alex in Belarus, which is now often assumed to be impossible (it isn’t, more on that later). Another reason is that it doesn’t try to compete with aforementioned multiband radios from China, so there is no FM broadcast band and – until now – no AM BC band, but most owners and potential buyers particularly in the US really wished it had at least the latter. Well, Alex obviously heard us! After the Belka DSP and the Belka DX, the new Belka is just called “Belka”, so in order to avoid any ambiguity I’m going to refer to this model as “Belka 2022”.

What’s new?

The most prominent addition to the Belka 2022 is the extended 0.1-31 MHz coverage, the previous version only started receiving at 1.5 MHz. With LW and MW included, its “pseudosynchronous” detector (as featured in venerable radios from Harris, Racal or Drake), the great filtering and the great frequency precision for hassle-free ECSS reception are promising that the “squirrel” is now an ultra-ultraportable companion for MW DXers as well.

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Belka DX updated to now cover mediumwave and longwave

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Many thanks to SWLing Post contributor, Dave Garr, who writes:

I have some interesting news for all of those Belka DX fans, Alex the guy behind this magnificent receiver has just announced the introduction of a new model. Ok so it is still called the Belka DX but it has now got a total frequency coverage of 100KHz to 31MHz so those that have put off buying because of lack of Long wave and Medium wave have now had their prayers answered. There has been no fanfare announcement about this but they have just updated their website with the new added frequency range. I am just waiting for the first review to appear before committing my hard earned cash.
Regards
Dave Gurr

Click here to check it out.

Excellent news. I’m sure this will make the Belka DX even more popular than it already is. I have to assume a ferrite bar hasn’t been added (there isn’t much room for one in the Belka series) so you would need to pair a proper MW/LM antenna antenna in order to fully take advantage of the new bands.

Thank you for the tip, Dave!

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File this under: you never know and . . . what’s the harm in experimenting?

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by Jock Elliott, KB2GOM

Ever since Thomas (our Maximum Leader) posted the latest DX Central MW Challenge, I’ve been curious . . . what could I hear if I gave it a shot?

Habitually, I get up early, between 4 and 5 am, so I decided to give it a try. Conventional wisdom is that, if you want to do AM (medium wave) DXing, you need a hot AM radio with a big ferrite bar, like the CCrane 2E . . .

Wanna guess what radio and antenna combo acquitted itself pretty well?

My old ham rig, an Icom IC-706 MkIIG, (which I wrote up here), hooked to my 50-foot wire indoor antenna, the horizontal room loop (which I wrote up here).

This AM’s listening, from my home outside Troy, NY, produced:

1170, WWVA — Wheeling, West Virginia
1180, WHAM — Rochester, NY
1200, Talk 1200 — Boston
1210, WPHT — Philadelphia

Now, before you hard-core AM DXers get all up in my face — Hey, I could hear those stations on the fillings in my teeth! — I’ll simply say that I get a kick out of hearing a distant station . . . any distant station . . . even it’s just a few hundred miles away. Sure, it’s not the astonishing stuff that Paul Walker and Gary DeBock accomplish, but to hear that faraway signal, crackling through the airwaves does me good.

Bottom line: you don’t need the latest and greatest optimized-for-the-task gear to give something a try . . . and you just might really enjoy it!

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2022-23 Season of the MW Frequency Challenge is underway with Week 1: 1160-1224 kHz

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Many thanks to SWLing Post contributor Loyd Van Horn at DX Central who shares the following announcement:

We are kicking off the 2022-23 DX season with the return of the MW Frequency Challenge! The MW Frequency Challenge officially started during the season premiere of our DX Central Live! livestream on YouTube on Friday, September 2022.

Our frequency range for this week’s challenge is 1160-1224 kHz!

A reminder of the rules for this season:

- Submitted loggings must be for receptions made between 0000 UTC Saturday, September 24, 2022 and 0200 UTC Saturday, October 1, 2022. Any station that transmits between 1160-1224 kHz will be accepted for the challenge.
- Submissions/loggings must be made with your own equipment, NO ONLINE SDRs (unless you own the online SDR). If you are logging receptions away from your home location, be sure to note that location on the submision form.
- Submissions must be entered on the Google Form using the link below. Logs posted through social media, DX club log submissions, email, etc. will not be accepted.
- Receptions can be for any station received within the frequency range. It does not need to be “new to you”, relogs are welcome as long as it occurred during the challenge period.

This week’s Google Form link is: https://forms.gle/EtKhNYc1qZhVmexh8

Good luck and best of DX!

73,

Loyd

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Video: Tour of AM Stereo Station KYET

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Many thanks to SWLing Post contributor, Dave (N9EWO), who writes:

Dan, shango066 on You Tube give us a nice little tour of KYET on 1070 kHz in Golden Valley Arizona which transmits in AM Stereo (6K day, 1 watt night). Harris solid state transmitter which is also shown in this video:

Click here to view on YouTube.

First part of his video explains the modified Realistic receiver (which he could not get working, well at least not yet):

Click here to view on YouTube.

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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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