My, how time flies. This is a post I have been meaning to write for nearly 3 years now. Back in late 2018, after a search for a small portable SW receiver, I purchased a C Crane Skywave SSB. It had a lot of the things I wanted in a portable radio and, at the time, I felt that it offered a lot for a receiver of it’s diminutive size.

Then I became aware of an even smaller receiver called the Belka-DX. Designed and manufactured by Alex EU1ME in Belarus, this positively tiny radio used SDR technology and, judging by the reviews I was reading and videos I was watching on YouTube, there was no other receiver it’s size that felt and performed like a much larger communications receiver in the way that this one apparently did. It all seemed very encouraging, so I went ahead and ordered one directly from Alex in Belarus. The first time I tried to order direct from his site, my bank denied the payment. I got on the phone to advise them that it was a legitimate charge, and they gave me a one hour window in which to put the transaction through again. I returned to the site, ordered the Belka-DX, and the order was accepted.

There are 3 ways I know of to purchase Belka receivers –

1. Directly from Alex EU1ME, in Belarus. Alex supplies 2 versions, with and without a built-in speaker. In order to accommodate the built-in speaker, that particular version has a slightly smaller battery. The version with the built-in speaker currently costs 475BYN, which at the exchange rate at the time of writing, is about US$145. As of Aug 9th 2024, Alex’s site carries the message that international shipping is currently unavailable. I notice that in the Q&A, Alex noted in July that he hopes to resume shipping to the US in about a month. This was the message he posted, on July 18th 2024 – “We do ship to the USA but at the moment we need to to undergo technical expert appraisal so that our Belarusian customs could allow export abroad. We hope to restart shipping in a month. Shipping cost to the USA is 13 USD.”
   
   
2. From Mobimax in Bulgaria. This is the same receiver, but with a larger speaker back that also has two small fold-out legs. This increases the depth of the Belka, but allows you to have a speaker as well as the larger 2500mAH battery. The markings for the input and output connections on the sides are etched into the metal. In addition, the LCD display is fitted with a screen protector into which are etched the words “HAM tactical RCVR”. Mobimax sell two different packages containing this receiver. The only difference is that the very slightly more expensive package includes a 3.5mm stereo to 3.5mm stereo cable, for plugging the IQ output of the Belka to your computer for use with SDR software. The version of the Belka that Mobimax supply is currently 227 Euros, which is about US$247. The package with the IQ cable is just a few Euros more.
   
   
3. There is an eBay seller in Bulgaria who sells the same version that Mobimax does, but for the (in my opinion) rather high price of US$350. The main reason I can see that buyers might go for this seller is the convenience and comfort factor of being able to pay with Paypal on a site they are familiar with.

A few weeks after ordering, a small box arrived from Belarus. In it was the Belka-DX wrapped in bubble wrap, and a small telescopic whip antenna of about 28.5″ in length. No documentation was included in the box, though it is available online. I didn’t take any pictures of it then, so here are some of it now, 3 years later.

In the above image, the backlight is on. In the next one, it is off. The backlight can be customized to be on all the time, off all the time, or to stay on for 12 seconds after any button is pushed or the tuning knob is turned. In the next photo, to the left of the BNC is a micro-USB connector that is used for charging the receiver. Underneath it is a red LED that lights when charging. To the right of the BNC antenna connector is the 3.5mm earphone jack. It is important that a stereo TRS jack is used here. A mono jack will short out one of the channels and can damage the audio IC –

At 82mm x 50mm x 20mm, this receiver is small!

I’m not sure if this is still true of the version that comes with the internal speaker direct from Alex, but the speaker holes in mine were slightly imperfect. It was evident that they had been drilled by hand. Not a big deal, but I thought it worth noting –

On the right side is the tuning encoder. It rotates smoothly with no click stops, for that “big receiver” smooth tuning feel. Also on the right side is a 3.5mm jack for the IQ output –

This was the second iteration of this receiver. The first one, named the Belka-DSP, covered 3.5-31 MHz. The Belka-DX covers 1.5-31 MHz. There is now a newer version, known simply as “Belka”, that has impressively continuous coverage from 0.1 MHz – 31MHz. Yes – 100KHz to 31MHz!

There are, by now, a number of quite detailed reviews of this series of receivers online. One such review, which gives a good overview of the capabilities of this pint-sized communications receiver, was written by Dave N9EWO. Since purchasing my Belka-DX almost 3 years ago, I have used it regularly. There are several features that I find very compelling, which distinguish it from many other shortwave portables –

1. There is no chuffing or soft-muting in between frequency steps. As a result, when on the smallest frequency step of 10Hz, the effect is of smooth, continuous tuning.
   
   
2. Unlike the CC Skywave SSB and, I believe, many other portables of it’s type, it is absolutely solid on SSB and CW receive. The carrier injection on my C Crane receiver was unsteady on strong signals, leading to chirping on CW, and similar frequency instability on SSB. For a short while, I owned a CountyComm GP-5 SSB, which was even more unsteady. The Belka-DX handles like a proper communications receiver in this regard, being rock steady on strong and weak signals alike.
   
   
3. The frequency display is accurate. As far as I can tell, it is accurate to better than 10-20Hz across the frequency range. Because of this, I can easily tune it to a frequency, and know that it is there. The Belka-DX employs a 0.5ppm TXCO and as a result, has a high level of frequency stability. My Skywave SSB only tunes in 1 KHz steps. To interpolate between those steps, you have to push a button to engage the fine tuning, but are not able to read the frequency accurately in between those 1 KHz points. For many users, this might not be an issue, but for those who listen out for weak beacons and other signals that are not on 1 KHz “channels”, the continuous tuning and accurate frequency readout on the Belka makes such monitoring much easier. A couple of years ago, I went on a 4 /12 month long campervan trip around 6 Western states. At the time, one of my interests was listening out for low-powered unlicensed HF beacons. Standing in the vast expanses of the desert with the little Belka-DX in my hand, hearing a weak low-powered CW beacon from hundreds of miles away was magical. These beacons are home-made affairs, and usually running somewhere between 30mW and a watt. Being able to dial in the precise frequency on a handheld receiver that is even sensitive with the set-top whip is a boon with such pursuits.
   
   
4. You can tailor the passband for each mode. With my C Crane Skywave, and I believe many other similar receivers, the adjustable filtering (if available) is audio filtering, and doesn’t occur in the RF stages. The Belka is an SDR, and the custom adjustable filtering is the equivalent of filtering in the RF or IF stages of a conventional superhet.

Two things that I wasn’t too keen on, and which have been amended in the 0.1-31MHz version –

1. In CW mode, the frequency display doesn’t indicate the operating frequency. For example, with a 700Hz sidetone pitch selected, if you want to receive a CW signal on 7030 KHz, you have to tune the receiver 700 Hz below that frequency i.e. to 7029.3 KHz. You do get used to it, but it would be nice to have it display the actual operating frequency in CW mode. In the newest version, the 0.1-31MHz version, I have read that the receiver displays the actual operating frequency in CW. If you’re concerned with being able to read out the exact frequency (if searching for weak beacons on non-standard frequencies, for example) you’ll still need to ensure that you tune to the correct sidetone frequency in order for the frequency readout to be accurate. Personally, I’d love a sidetone feature for this, but I doubt that too many others would consider it to be an essential feature in a receiver (as opposed to a transceiver).
   
   
2. When stepping through the memory channels, you cannot hear those channels as you cycle through them. In order to hear the selected channel, you have to press the appropriate button to select and load it. Thus, you cannot easily scan through a number of preset memory channels to listen for activity. As with 1 above, I this has been remedied in the newest version of the Belka.

The audio quality from the Belka-DX is excellent when used with earbuds. The internal speaker doesn’t do it justice, though it is very useful when taking the receiver on outings. Power from the audio amplifier is adequate for most applications, though when plugging an external speaker in, it helps to use one that is sensitive. Some people use powered speakers. I have two external speakers on the bench, both unpowered, that I use with it. The main one is an MFJ-281 ClearTone speaker. It is sensitive, and produces good volume. The audio response from the mylar cone is restricted, and what I would characterize as communications quality. Audio is clear and intelligible. The speaker appears to have a natural resonance at around 650-700Hz, which is useful for CW. For those times when I need a little more fidelity, such as when listening to strong SWBC stations, or hams on AM, I use an old and compact hi-fi speaker manufactured by Cambridge Soundworks. It was discarded by one of my neighbors, and appears to be a mid-range unit. It is not as sensitive as the MFJ ClearTone speaker, but the Belka will still provide enough drive in a small, quiet room, which perfectly describes the conditions in my shack.

The small size and slim dimensions of the Belka-DX make it ideal for traveling. When using it at home with an external antenna connected, the ergonomics and ease of use are much improved when mounted on some kind of stand. There are a number of stands available, as well as files for those who wish to 3D-print their own. I remembered a clamp I once bought, that was designed to hold a cellphone for attaching it to a tripod, for making videos. The Belka is not quite as wide as a cellphone, so I used a couple of pieces of dense foam to pad it out, and screwed it to a small tabletop tripod. It works quite well, and improves the ease of use drastically when listening at home. When mounted like this, it feels like a serious and very usable SWL set-up. In the various SWL groups on FB that I frequent, I often see questions from folk asking about receivers that are good for SWL’ing. Portables such as the Tecsun PL-880, along with other similar receivers are often recommended. I think that this Belka makes an excellent receiver for all-round shortwave listening. It is not available in as many outlets as the more traditional shortwave portables, which is why I think that it isn’t as popular in the SWL community as it should be. If you are listening mainly to AM broadcasts on shortwave, then many of the portables will most likely work well. If you do a lot of SSB and CW listening though, the Belka is a solid and, to my mind, preferable option.

In the following picture, my Belka is mounted on a mini tripod (an Ultrapod) and connected to the MFJ ClearTone speaker. Behind and underneath the Belka, you can just see an Altoids tin which contains a high pass filter with a cut-off at about 2700 KHz. It was designed to prevent overload from strong local AM broadcast stations. More on that later in this post.

The Belka-DX is surprisingly sensitive when listening outdoors with the included telescopic whip. It does need a counterpoise, or the received signal strength suffers greatly. If you are holding the receiver, then your body acts as the counterpoise. If you are listening on earbuds or headphones, then the headphone cord acts as a counterpoise. If the receiver is sitting on a surface and using the internal speaker, then you’ll need to connect a counterpoise wire somehow. At home, it works really well when connected to my outdoor antena, which is a doublet at 47 feet, cut roughly for 40M, fed with 300 ohm twinlead, and matched to coax at the entrance to the shack, with a balun and Elecraft T1 tuner. I tune the T1 by squirting RF into it on the nearest amateur band. If you are using your outdoor antenna for listening only, then a simpler arrangement would suffice. This just happens to be the one antenna I also use for my ham exploits.

I live in a densely populated urban area, within a few miles of several medium power (5KW) AM broadcast stations. They often break through when I am using the external antenna with receivers that don’t have narrow filtering on the antenna input. My Belka-DX experiences strong AM breakthrough when used on the external antenna at all frequencies up to 4530 KHz. The moment I tune above 4530 – even by a single 10Hz step, the breakthrough stops instantly, suggesting that a different bandpass filter is switched in at the point. According to the manufacturer-supplied block diagram of the first version of Belka, known as the Belka-DSP, the input bandpass filters are from 3.5-7.5MHz, 7.5-15MHz, and 15-30MHz. The block diagram can be seen on this page by Fernando Duarte. I assume that for the Belka-DX, with it’s extended coverage down to 1.5 MHz, one of the bandpass filter crossover points is at 4530 KHz, the point above which all AM BC band breakthrough stops.

To solve this problem of breakthrough, I resorted to a little high pass filter that I have used successfully with other receiver projects. It’s a high pass filter that was designed by David WA7JHZ, details of which were given in K4SWL’s very wonderful and informative SWLing Post blog. You can see it here. David built his with molded chokes. I built versions with both molded chokes and toroids, and compared the response curves.

Trusty Altoids tins to the rescue. Here’s the version built with molded chokes, purchased from Tayda Electronics. The chokes are mounted vertically, and are a little hard to see in this image –

The small holes in the base of the tin were left over from a previous project that didn’t work out.

Then I built another high pass filter with toroids instead of molded chokes. I figured the toroids should have slightly higher Q and would present a better response curve. All 4 inductors were wound on T37-6 toroid cores with 26 AWG wire. The 2.7µH inductors had 30 turns and the 1µH ones 18 turns. The wires supported them about 4 or 5mm above the ground plane of the Altoid tin –

Dang, after all these years, Altoids tins still make very serviceable and cheap enclosures for small projects!

These filters were designed for input and output impedances of 50Ω. My one external HF antenna is a 40M doublet fed with 300Ω twinlead, and matched to 50Ω coax with a 1:1 balun and Elecraft T1 tuner. As mentioned previously, I briefly transmit a small amount of power on the nearest ham band to where I want to listen, to tune the T1. A manual tuner could be used here instead, and tuned for maximum noise. For listening, this is not too critical a procedure, and a single tune will cover the receiver for listening on a wide range of frequencies. The antenna input of the Belka is matched for the high impedance of the supplied short telescopic whip, and not for a 50Ω antenna. Nevertheless, I went ahead and plugged both versions of this HPF in between the antenna and the receiver, and they both served to completely eradicate every single trace of AM BC band breakthrough.

Using a NanoVNA, I measured the response curve of both filters from 1.5 MHz to 30MHz. Here’s the curve for the filter built with molded chokes –

The 3dB cutoff point of this filter was actually 3 MHz, and the insertion loss small, with a virtually flat response from the 80M band up to the top of the 10M band. Here’s a close-up of the response between 1.5 MHz and 4 MHz –

The insertion loss of the toroid filter in the passband was a little lower, For all practical purposes though, there would be no discernible difference between the two filters. If you hate winding toroids, then by all means, build this filter with molded chokes, and it will kill your AM BC band breakthrough just as effectively as if you’d built it with toroids. Here’s the response curve of the toroid version from 1500 KHz to 30 MHz –

And from 1500 KHz to 4 MHz, giving a closer look at the area around the the 3dB cutoff point –

There are quite a few internally generated birdies throughout the whole coverage range. However, the majority of them are only audible with no antenna connected, and are masked by band noise. The others, although audible over the band noise, are not troublesome. For a receiver this compact, and with this overall level of performance, it’s a small price to pay. I rarely noticed them during normal use. It would be nice for the end-user to have a way to update the firmware, though the extended coverage down to 100KHz that the new (V3) Belka enjoys required a hardware upgrade in the form of an extra bandpass filter.

For a more complete description of the improvements made with the newest Belka version, see 13dka’s guest post on Thomas K4SWl’s excellent SWLing Post blog. In short, the Belka is a fantastic general coverage shortwave receiver. It performs and handles like much larger tabletop communications receivers. It is so small that it can be carried anywhere with great ease, making the decision to do a little SWL’ing while on a hike, a walk, or any trip, a no-brainer. You can do a lot of serious shortwave listening with this receiver. Ordering direct from Alex in Belarus offers by far the lowest price and is, in my opinion, the way to go. When I think of my first communications receiver, an old, huge and very heavy British military R107 boat anchor, it is amazing to think that this light and svelte pocketable Belka-DX handily runs circles around it. An SWL can positively rule the shortwaves with this tiny and light miracle of wireless!

There are many other, far more comprehensive reviews on this receiver, but I have been wanting to sing the praises of the Belka (which is Russian for squirrel) for a long time now. I needed to get this out.

My, how time flies. This is a post I have been meaning to write for nearly 3 years now. Back in late 2018, after a search for a small portable SW receiver, I purchased a C Crane Skywave SSB. It had a lot of the things I wanted in a portable radio and, at the time, I felt that it offered a lot for a receiver of it’s diminutive size.

Then I became aware of an even smaller receiver called the Belka-DX. Designed and manufactured by Alex EU1ME in Belarus, this positively tiny radio used SDR technology and, judging by the reviews I was reading and videos I was watching on YouTube, there was no other receiver it’s size that felt and performed like a much larger communications receiver in the way that this one apparently did. It all seemed very encouraging, so I went ahead and ordered one directly from Alex in Belarus. The first time I tried to order direct from his site, my bank denied the payment. I got on the phone to advise them that it was a legitimate charge, and they gave me a one hour window in which to put the transaction through again. I returned to the site, ordered the Belka-DX, and the order was accepted.

There are 3 ways I know of to purchase Belka receivers –

1. Directly from Alex EU1ME, in Belarus. Alex supplies 2 versions, with and without a built-in speaker. In order to accommodate the built-in speaker, that particular version has a slightly smaller battery. The version with the built-in speaker currently costs 475BYN, which at the exchange rate at the time of writing, is about US$145. As of Aug 9th 2024, Alex’s site carries the message that international shipping is currently unavailable. I notice that in the Q&A, Alex noted in July that he hopes to resume shipping to the US in about a month. This was the message he posted, on July 18th 2024 – “We do ship to the USA but at the moment we need to to undergo technical expert appraisal so that our Belarusian customs could allow export abroad. We hope to restart shipping in a month. Shipping cost to the USA is 13 USD.”
   
   
2. From Mobimax in Bulgaria. This is the same receiver, but with a larger speaker back that also has two small fold-out legs. This increases the depth of the Belka, but allows you to have a speaker as well as the larger 2500mAH battery. The markings for the input and output connections on the sides are etched into the metal. In addition, the LCD display is fitted with a screen protector into which are etched the words “HAM tactical RCVR”. Mobimax sell two different packages containing this receiver. The only difference is that the very slightly more expensive package includes a 3.5mm stereo to 3.5mm stereo cable, for plugging the IQ output of the Belka to your computer for use with SDR software. The version of the Belka that Mobimax supply is currently 227 Euros, which is about US$247. The package with the IQ cable is just a few Euros more.
   
   
3. There is an eBay seller in Bulgaria who sells the same version that Mobimax does, but for the (in my opinion) rather high price of US$350. The main reason I can see that buyers might go for this seller is the convenience and comfort factor of being able to pay with Paypal on a site they are familiar with.

A few weeks after ordering, a small box arrived from Belarus. In it was the Belka-DX wrapped in bubble wrap, and a small telescopic whip antenna of about 28.5″ in length. No documentation was included in the box, though it is available online. I didn’t take any pictures of it then, so here are some of it now, 3 years later.

In the above image, the backlight is on. In the next one, it is off. The backlight can be customized to be on all the time, off all the time, or to stay on for 12 seconds after any button is pushed or the tuning knob is turned. In the next photo, to the left of the BNC is a micro-USB connector that is used for charging the receiver. Underneath it is a red LED that lights when charging. To the right of the BNC antenna connector is the 3.5mm earphone jack. It is important that a stereo TRS jack is used here. A mono jack will short out one of the channels and can damage the audio IC –

At 82mm x 50mm x 20mm, this receiver is small!

I’m not sure if this is still true of the version that comes with the internal speaker direct from Alex, but the speaker holes in mine were slightly imperfect. It was evident that they had been drilled by hand. Not a big deal, but I thought it worth noting –

On the right side is the tuning encoder. It rotates smoothly with no click stops, for that “big receiver” smooth tuning feel. Also on the right side is a 3.5mm jack for the IQ output –

This was the second iteration of this receiver. The first one, named the Belka-DSP, covered 3.5-31 MHz. The Belka-DX covers 1.5-31 MHz. There is now a newer version, known simply as “Belka”, that has impressively continuous coverage from 0.1 MHz – 31MHz. Yes – 100KHz to 31MHz!

There are, by now, a number of quite detailed reviews of this series of receivers online. One such review, which gives a good overview of the capabilities of this pint-sized communications receiver, was written by Dave N9EWO. Since purchasing my Belka-DX almost 3 years ago, I have used it regularly. There are several features that I find very compelling, which distinguish it from many other shortwave portables –

1. There is no chuffing or soft-muting in between frequency steps. As a result, when on the smallest frequency step of 10Hz, the effect is of smooth, continuous tuning.
   
   
2. Unlike the CC Skywave SSB and, I believe, many other portables of it’s type, it is absolutely solid on SSB and CW receive. The carrier injection on my C Crane receiver was unsteady on strong signals, leading to chirping on CW, and similar frequency instability on SSB. For a short while, I owned a CountyComm GP-5 SSB, which was even more unsteady. The Belka-DX handles like a proper communications receiver in this regard, being rock steady on strong and weak signals alike.
   
   
3. The frequency display is accurate. As far as I can tell, it is accurate to better than 10-20Hz across the frequency range. Because of this, I can easily tune it to a frequency, and know that it is there. The Belka-DX employs a 0.5ppm TXCO and as a result, has a high level of frequency stability. My Skywave SSB only tunes in 1 KHz steps. To interpolate between those steps, you have to push a button to engage the fine tuning, but are not able to read the frequency accurately in between those 1 KHz points. For many users, this might not be an issue, but for those who listen out for weak beacons and other signals that are not on 1 KHz “channels”, the continuous tuning and accurate frequency readout on the Belka makes such monitoring much easier. A couple of years ago, I went on a 4 /12 month long campervan trip around 6 Western states. At the time, one of my interests was listening out for low-powered unlicensed HF beacons. Standing in the vast expanses of the desert with the little Belka-DX in my hand, hearing a weak low-powered CW beacon from hundreds of miles away was magical. These beacons are home-made affairs, and usually running somewhere between 30mW and a watt. Being able to dial in the precise frequency on a handheld receiver that is even sensitive with the set-top whip is a boon with such pursuits.
   
   
4. You can tailor the passband for each mode. With my C Crane Skywave, and I believe many other similar receivers, the adjustable filtering (if available) is audio filtering, and doesn’t occur in the RF stages. The Belka is an SDR, and the custom adjustable filtering is the equivalent of filtering in the RF or IF stages of a conventional superhet.

Two things that I wasn’t too keen on, and which have been amended in the 0.1-31MHz version –

1. In CW mode, the frequency display doesn’t indicate the operating frequency. For example, with a 700Hz sidetone pitch selected, if you want to receive a CW signal on 7030 KHz, you have to tune the receiver 700 Hz below that frequency i.e. to 7029.3 KHz. You do get used to it, but it would be nice to have it display the actual operating frequency in CW mode. In the newest version, the 0.1-31MHz version, I have read that the receiver displays the actual operating frequency in CW. If you’re concerned with being able to read out the exact frequency (if searching for weak beacons on non-standard frequencies, for example) you’ll still need to ensure that you tune to the correct sidetone frequency in order for the frequency readout to be accurate. Personally, I’d love a sidetone feature for this, but I doubt that too many others would consider it to be an essential feature in a receiver (as opposed to a transceiver).
   
   
2. When stepping through the memory channels, you cannot hear those channels as you cycle through them. In order to hear the selected channel, you have to press the appropriate button to select and load it. Thus, you cannot easily scan through a number of preset memory channels to listen for activity. As with 1 above, I this has been remedied in the newest version of the Belka.

The audio quality from the Belka-DX is excellent when used with earbuds. The internal speaker doesn’t do it justice, though it is very useful when taking the receiver on outings. Power from the audio amplifier is adequate for most applications, though when plugging an external speaker in, it helps to use one that is sensitive. Some people use powered speakers. I have two external speakers on the bench, both unpowered, that I use with it. The main one is an MFJ-281 ClearTone speaker. It is sensitive, and produces good volume. The audio response from the mylar cone is restricted, and what I would characterize as communications quality. Audio is clear and intelligible. The speaker appears to have a natural resonance at around 650-700Hz, which is useful for CW. For those times when I need a little more fidelity, such as when listening to strong SWBC stations, or hams on AM, I use an old and compact hi-fi speaker manufactured by Cambridge Soundworks. It was discarded by one of my neighbors, and appears to be a mid-range unit. It is not as sensitive as the MFJ ClearTone speaker, but the Belka will still provide enough drive in a small, quiet room, which perfectly describes the conditions in my shack.

The small size and slim dimensions of the Belka-DX make it ideal for traveling. When using it at home with an external antenna connected, the ergonomics and ease of use are much improved when mounted on some kind of stand. There are a number of stands available, as well as files for those who wish to 3D-print their own. I remembered a clamp I once bought, that was designed to hold a cellphone for attaching it to a tripod, for making videos. The Belka is not quite as wide as a cellphone, so I used a couple of pieces of dense foam to pad it out, and screwed it to a small tabletop tripod. It works quite well, and improves the ease of use drastically when listening at home. When mounted like this, it feels like a serious and very usable SWL set-up. In the various SWL groups on FB that I frequent, I often see questions from folk asking about receivers that are good for SWL’ing. Portables such as the Tecsun PL-880, along with other similar receivers are often recommended. I think that this Belka makes an excellent receiver for all-round shortwave listening. It is not available in as many outlets as the more traditional shortwave portables, which is why I think that it isn’t as popular in the SWL community as it should be. If you are listening mainly to AM broadcasts on shortwave, then many of the portables will most likely work well. If you do a lot of SSB and CW listening though, the Belka is a solid and, to my mind, preferable option.

In the following picture, my Belka is mounted on a mini tripod (an Ultrapod) and connected to the MFJ ClearTone speaker. Behind and underneath the Belka, you can just see an Altoids tin which contains a high pass filter with a cut-off at about 2700 KHz. It was designed to prevent overload from strong local AM broadcast stations. More on that later in this post.

The Belka-DX is surprisingly sensitive when listening outdoors with the included telescopic whip. It does need a counterpoise, or the received signal strength suffers greatly. If you are holding the receiver, then your body acts as the counterpoise. If you are listening on earbuds or headphones, then the headphone cord acts as a counterpoise. If the receiver is sitting on a surface and using the internal speaker, then you’ll need to connect a counterpoise wire somehow. At home, it works really well when connected to my outdoor antena, which is a doublet at 47 feet, cut roughly for 40M, fed with 300 ohm twinlead, and matched to coax at the entrance to the shack, with a balun and Elecraft T1 tuner. I tune the T1 by squirting RF into it on the nearest amateur band. If you are using your outdoor antenna for listening only, then a simpler arrangement would suffice. This just happens to be the one antenna I also use for my ham exploits.

I live in a densely populated urban area, within a few miles of several medium power (5KW) AM broadcast stations. They often break through when I am using the external antenna with receivers that don’t have narrow filtering on the antenna input. My Belka-DX experiences strong AM breakthrough when used on the external antenna at all frequencies up to 4530 KHz. The moment I tune above 4530 – even by a single 10Hz step, the breakthrough stops instantly, suggesting that a different bandpass filter is switched in at the point. According to the manufacturer-supplied block diagram of the first version of Belka, known as the Belka-DSP, the input bandpass filters are from 3.5-7.5MHz, 7.5-15MHz, and 15-30MHz. The block diagram can be seen on this page by Fernando Duarte. I assume that for the Belka-DX, with it’s extended coverage down to 1.5 MHz, one of the bandpass filter crossover points is at 4530 KHz, the point above which all AM BC band breakthrough stops.

To solve this problem of breakthrough, I resorted to a little high pass filter that I have used successfully with other receiver projects. It’s a high pass filter that was designed by David WA7JHZ, details of which were given in K4SWL’s very wonderful and informative SWLing Post blog. You can see it here. David built his with molded chokes. I built versions with both molded chokes and toroids, and compared the response curves.

Trusty Altoids tins to the rescue. Here’s the version built with molded chokes, purchased from Tayda Electronics. The chokes are mounted vertically, and are a little hard to see in this image –

The small holes in the base of the tin were left over from a previous project that didn’t work out.

Then I built another high pass filter with toroids instead of molded chokes. I figured the toroids should have slightly higher Q and would present a better response curve. All 4 inductors were wound on T37-6 toroid cores with 26 AWG wire. The 2.7µH inductors had 30 turns and the 1µH ones 18 turns. The wires supported them about 4 or 5mm above the ground plane of the Altoid tin –

Dang, after all these years, Altoids tins still make very serviceable and cheap enclosures for small projects!

These filters were designed for input and output impedances of 50Ω. My one external HF antenna is a 40M doublet fed with 300Ω twinlead, and matched to 50Ω coax with a 1:1 balun and Elecraft T1 tuner. As mentioned previously, I briefly transmit a small amount of power on the nearest ham band to where I want to listen, to tune the T1. A manual tuner could be used here instead, and tuned for maximum noise. For listening, this is not too critical a procedure, and a single tune will cover the receiver for listening on a wide range of frequencies. The antenna input of the Belka is matched for the high impedance of the supplied short telescopic whip, and not for a 50Ω antenna. Nevertheless, I went ahead and plugged both versions of this HPF in between the antenna and the receiver, and they both served to completely eradicate every single trace of AM BC band breakthrough.

Using a NanoVNA, I measured the response curve of both filters from 1.5 MHz to 30MHz. Here’s the curve for the filter built with molded chokes –

The 3dB cutoff point of this filter was actually 3 MHz, and the insertion loss small, with a virtually flat response from the 80M band up to the top of the 10M band. Here’s a close-up of the response between 1.5 MHz and 4 MHz –

The insertion loss of the toroid filter in the passband was a little lower, For all practical purposes though, there would be no discernible difference between the two filters. If you hate winding toroids, then by all means, build this filter with molded chokes, and it will kill your AM BC band breakthrough just as effectively as if you’d built it with toroids. Here’s the response curve of the toroid version from 1500 KHz to 30 MHz –

And from 1500 KHz to 4 MHz, giving a closer look at the area around the the 3dB cutoff point –

There are quite a few internally generated birdies throughout the whole coverage range. However, the majority of them are only audible with no antenna connected, and are masked by band noise. The others, although audible over the band noise, are not troublesome. For a receiver this compact, and with this overall level of performance, it’s a small price to pay. I rarely noticed them during normal use. It would be nice for the end-user to have a way to update the firmware, though the extended coverage down to 100KHz that the new (V3) Belka enjoys required a hardware upgrade in the form of an extra bandpass filter.

For a more complete description of the improvements made with the newest Belka version, see 13dka’s guest post on Thomas K4SWl’s excellent SWLing Post blog. In short, the Belka is a fantastic general coverage shortwave receiver. It performs and handles like much larger tabletop communications receivers. It is so small that it can be carried anywhere with great ease, making the decision to do a little SWL’ing while on a hike, a walk, or any trip, a no-brainer. You can do a lot of serious shortwave listening with this receiver. Ordering direct from Alex in Belarus offers by far the lowest price and is, in my opinion, the way to go. When I think of my first communications receiver, an old, huge and very heavy British military R107 boat anchor, it is amazing to think that this light and svelte pocketable Belka-DX handily runs circles around it. An SWL can positively rule the shortwaves with this tiny and light miracle of wireless!

There are many other, far more comprehensive reviews on this receiver, but I have been wanting to sing the praises of the Belka (which is Russian for squirrel) for a long time now. I needed to get this out.

A couple of years ago I built a Matrix Synapse server and connected it to the decentralised global Matrix chat network that is federated world wide by enthusiasts who host their own Matrix servers. Due to the enthusiasm for a decentralised network the Matrix has grown exponentially and is now an established force in the world of Opensource global communication services.

When I built my server and configured it online my aim was to bring together an enthusiastic group of Radio Amateurs (Radio HAMs) who could build a friendly, welcoming community where people could share, learn and have fun with other liked minded individuals without all the nonsense you see on commercial social media platforms.

Overtime we’ve increased the number of rooms available in the HAM Radio space and the number of subjects covered. This has grown organically as our community has grown and we’ve ventured together into new areas of the hobby.

From the community a number of projects have spawned including the Opensource.radio Wiki that Mike, DK1MI is sponsoring that aims to detail all the Opensource HAM Radio software, Hardware and projects in one centralised site on the internet. This is a great project and one I am very happy to contribute to.

Thanks to Mike, DK1MI we now also have our own Matrix AllStarLink node available. This is a great resource for the community as it is often not possible for all of us to communicate via the radio waves due to geo-location, time zones, local planning regulations etc. Having this 24/7 internet based resource makes it a lot easier for the community to chat at any time even when propagation on the HF bands isn’t in our favour.

Mike, DK1MI has written an excellent article on the Matrix AllStarNode and more, I highly recommend you take a look at it.

We also have a very active satellite room with regular nets on the QO-100 satellite. With such a great range of rooms and subjects there’s plenty to read and talk about with the community.

If you fancy being part of this growing, enthusiastic group of Radio Amateurs and Short Wave Listeners (SWLs) then click on the link below and come and say hello, a warm welcome awaits!

https://m0aws.co.uk/matrix

More soon …

Listening to the shortwave commercial stations (along with CB radio) has been a key gateway activity for entry into amateur radio. That was back when commercial shortwave was vibrant and perhaps in its heyday. There is still a very active set of SWLs contributing to the popular SWLing.com website and the legacy work by the well-known Van Horn family to just name a couple. The Spectrum Monitor publishes information about shortwave listening, too. Of course, the Grand Daddy publication, the World Radio TV Handbook is still around. But do amateur operators still listen to the shortwave radio bands? In this article, I want to address the question I just raised with a clear answer: They still do in Canada!

The Radio Amateurs of Canada (RAC) fielded a national survey of Canadian hams in 2021. A total of 2,089 responses were received, of which 1,630 (78%) were from RAC members. Approximately one-third of all RAC members took the time to complete the survey. This is an example of “voluntary response sample” and is not a probability survey. The final report compared responses to known population characteristics which suggested that the realized sample data is generally representative of Province and license characteristics. I’ve just completed a full report from the data which is available on my FoxMikeHotel.com website. The results on shortwave listening are the focus of this article.

The results show that indeed Canadian amateurs listen to the shortwave frequencies outside of ham radio bands. Out of 38 specific operating activities, over a fourth (28.8%) of Canadian amateurs said they are involved in shortwave listening in a typical month. This was ranked 16^th out of 38, ahead of QRP operations, Elmering, weather spotting, and other activities thought to be popular in amateur radio. This result may be surprising to the reader. But my further analysis shows a clearer picture of how traditional shortwave listing activity is integrated with other ham activities.

I have included in Figure 1 a map of all license-holders in Canada from the amateur radio regulator, ISED. The provided licensee address was georeferenced to the street-level for the vast majority and city-level for the remainder. There is also a bar chart showing how SWLing varies by Province.

Amateurs in Canada are concentrated all along the Southern border and in the urban centers of the Southeastern seaboard. There is another concentration on the Western coast near Vancouver. For the survey results, the bar chart in the bottom panel of Figure 1 illustrates how shortwave listening varies. A majority of hams in Newfoundland and the Northwest Territory use shortwave radio for listening. Those in Saskatchewan and Manitoba round out those Provinces above the overall survey mark of 28.8 percent. Excluding Nunavut Province with only 2 survey respondents, the lowest engagement in SWLing is Alberta. The remaining Provinces are about equal, in the lower twenty-percent figure.

Do these results make sense? The physical isolation of the two highest Provinces makes using shortwave broadcasts very practical in many ways. But there is more to it as I investigated whether SWLing is a more obscure activity in ham radio or is it more integrated into portfolio of things that current amateur operators do today?

In Table 1, I summarize my crosstabulation of shortwave listening by other activities (some 37 tables). The three groups summarized in the table reflect whether there was a statistically significant relationship between the two activities and, if so, whether SWLing was greater or less when the ham said they participate in the comparison activity. If there is no significant relationship, then shortwave listening is about the same whether the other activity is engaged in or not. If shortwave listening is a surprising yet obscure activity, there would be few other activities associated with it. Or, perhaps there might be no relationship at all with a random assortment of hams tuning into to those bands.

What the results in Table 1 demonstrate is how significantly integrated shortwave listening is with a number of activities central to the hobby. There are only seven activities without an association and one with a negative relationship. Contesters tend to pursue SWLing significantly less. This is the opposite, however, of what DXers report. Ham operators who listen to shortwave bands also practice a variety of popular activities in their practice of the hobby. These findings tend to remove any doubt as to whether listening to shortwave radio bands is fully an integrated part of contemporary amateur radio in Canada.

Another question about these results is whether it is simply a residual activity of the large Baby Boom cohort? Should this be the case, SWLing is likely to age out of existence over the next couple of decades. If so, shortwave listening would be highest among the most senior survey respondents and lowest among the youngest.

In Figure 2, I constructed a line chart of shortwave usage by age group. There is a clear downward trend as SWLing is highest among younger hams than more senior ones. The significance test suggests that this overall age pattern is not significant. The result is that the survey result of a quarter or more of Canadian hams engaging in shortwave listening is not a holdover of amateurs from a previous era of the hobby as younger hams.

Even with there being a non-significant trend in opposition to the Baby Boomer remnant hypothesis, I examined how long these hams had been licensed (tenure) and a complementary question in the survey regarding long many years they had been active. Perhaps it is not age per se but length of experience as a licensed or active ham that might influence whether nor not shortwave listening is attractive. These results, too, showed almost no difference regarding shortwave listening and length of experience or activity in the hobby. This are positive findings for shortwave band usage outside of amateur radio.

To further assess how shortwave listening might be linked to other factors, I compared the rural-to-urban locations of amateurs in the survey. There are no significant differences even when compared within these Provinces. The rural-to-urban locale does not explain why some Provinces have higher shortwave listening levels than others.

To conclude, these are somewhat unexpected findings based upon the rhetoric that ham radio operators tell themselves in the public sphere. We frequently hear that shortwave listening is passe, that the commercial and government broadcasters are retreating, and so forth. These may be factually the case from the supply-side of non-ham shortwave transmissions. But the hams in Canada do listen to shortwave broadcasts or one type or another in addition to participating in the core set of activities that comprises amateur radio. Contesting is the sole specialty that is negatively related to such listening. By contrast, DXers are more likely to listen (30.2% vs 23.6%). There are Provincial variations in listening but no patterns within any of them that vary along the rural-to-urban continuum.

The relationship of SWLing to the rest of the amateur radio hobby’s activities appears well-integrated. While the broadcast sector of the shortwave industry is at a low ebb right now, amateur radio in Canada still embraces listening to the non-ham bands. We do not know how this national survey of Canadian amateurs may compare to those of other nations. However, it is the sole survey of which I am aware that measures the activities of amateur radio operators in such detail. Until we do have comparative surveys, the RAC Survey 2021 is our only objective insight into ham radio activities.

Some readers may view these surprising results through their own “personal windshield” of listening experiences. “Why, I don’t know any hams who listen to shortwave broadcasts,” they might say. Others could counter, “Well, we need some “good” survey data on this issue.” I’ve spent a career conducting surveys, teaching survey research methods to PhD students (and fellow faculty), and advising some of the largest survey organizations in the world, such as NORC at the University of Chicago, the SRC at the University of Michigan, and the USDA National Agricultural Statistics Service to name a few. The RAC Survey of 2021 is not a high quality statistical probability sample costing a few hundred thousand of dollars. But it is the best one I’ve seen to date on a national scale with behavioral measures of amateur radio operators. So while the reader’s experiences on SWLing might indeed be differ, it is the aggregate picture that we have never had national level results like those in the RAC Survey 2021. Do they apply to the U.S.? Well, would you rather go just with your personal windshield to generalize or take the picture these results present as our best guesstimate for similar behavior in the States?

 Yes, I know. It's been a while since I posted, just under a year. Unfortunately, as we all know, 2020 is not a normal year. 

Aside from attending the amateur radio training session for the 2020 Boston Marathon, the Marathon was delayed until September and ultimately cancelled and replaced with a virtual event. The same goes for the 2020 Head of the Charles Regatta. 

I was planning on going to my first Hamvention, but that too was cancelled. As was the May and October editions of NEAR-Fest. My last hope for some ham action was the Northeast HamXposition, but alas, it was also cancelled. As have all the monthly MIT Fleas for the year.

It's not all bad though, we've still had NSRA meetings via Zoom and continued them into summer, which usually is a break period for the club. Also, there have been virtual ham expos and fests online, such as the QSO Today Ham Expo and the HamXposition is going virtual too.

I just recently got back from a 3 month work deployment on Nantucket, I didn't really use their repeater much to do be being busy with work and mic shyness, but it was good nonetheless, and I did do alot of shortwave listening while I was there. I did manage to check in the NSRA's Sunday Night Net via Echolink a lot.

Now that I got back home, I turned my virtual scanner back on, which I've migrated to a Raspberry Pi 4 because of Wi-Fi issues with the Lenovo ThinkCentre. 

But that's been my year in ham and radio in general in a nutshell.

Owen Gariott a été le premier astronaute à transmettre en direction de la terre pour les radioamateurs depuis l’espace, ceci à bord la navette spatiale Columbia lors de la mission STS-9 en 1983. Cet événement avait suscité un vif intérêt parmi les radioamateurs. Pouvoir communiquer avec un astronaute à bord d’une navette spatiale était le Graal que nous tous voulions obtenir. A cette époque, je travaillais à Radio Suisse Internationale et bien aimé pouvoir faire un enregistrement lors d’un de ses passage au dessus le centre de l’Europe. Si j’ai bien pu le recevoir, j’étais très mal placé pour faire un enregistrement de qualité. Malheureusement ce que j’avais pu enregistrer n’était pas diffusable. C’est alors que je me suis approché d’un radioamateur qui travaillait également à la SSR, lui à Lausanne qui lui avait pu mettre la main sur un enregistrement du même passage et a pu le diffuser sur les ondes de la Radio Suisse Romande en plein prime time pendant les informations. Ni une ni deux, on décide de commander un feed entre les studios de Lausanne et Berne pour s’échanger les enregistrements.
Ainsi j’ai pu disposer d’un son de qualité qui a pu être également diffusé sur les ondes courtes de Radio Suisse Internationale. C’était un souvenir mémorable, avec le décès de notre héros de l’espace, je souhaite lui faire cet hommage. Il nous a offert du rêve et a été le précurseur de ce qui se fait maintenant grâce à ARISS qui a offert et offre encore aujourd’hui ce même rêve à des centaines d’étudiants ou écoliers partout dans le monde. Le radio-amateurisme est vraiment un hobby formidable qui permet ces échanges avec ces projets académiques qui ont fait la fierté de tout ces jeunes qui ont eu la chance de parler à un astronaute.

Voici les enregistrements de l’époque:

W5LFL au journal du soir de la Radio Suisse Romande (1983)

W5LFL dans l’émission « The Two Bobs » Swiss Radio International (1983)