Remember yesterday when I mentioned the latest addition to my POTA setup, the Xiegu 5105 QRP rig….

Well this morning I decided to test it out and see how much work I would have to do with setting the parameters such as mic gain, processor, to make it sound like me… I was also testing out my EARCHI 9:1 unun with a 29.5 foot random wire to see how it would play with the built in AT of the 5105.

I figured I might as well do the testing at a POTA location just in case I was able to turn the test into an activation.

For this I chose Fort Frontenac POTA CA-5303. Its fairly easy to get there via the Kingston Transit system and its also close to downtown and all the amenities I might need. In the North East corner of the picture you will notice some white lines on the ground.

They are actually the walls of what’s left of that part of the Fort. Also the only parts of the Historic Site that is open to the public.

I leaned my MFJ 33 foot mast (supporting the 9:1 and wire in the vertical configuration) up against the tree.

And then ran the COAX over to the remains of the wall and set up my radio there and started operating.

My first contact was on 7.255 with the NCS of the ECARS net. He did hear me and considering I was QRP I was pleased. He did tell me that my audio seemed hot as if I was overdriving things. Lowering my voice seemed to help.

After that I looked at POTA Spots and managed to get W2IDG and VE3FI into the log from their parks and then finished up with the NCS of the MidCars net on 7.258.. All contacts were made on 40m SSB. I tried 20 SSB and was hearing lots of stations including a POTA Activation in VO1 but no luck breaking any of the pileups.

Then I figured it was time to get home and try to re configure the radio to my liking… I turned off the Speech Processor and lowered the Mic Gain from 60 to 40. Over the next few days I will get out again and see what else I have to do to get things sounding right.

Till then

73bob

I have been emailed details of a new RTTY contest which will run for the first time this year on Friday 4th October 2024. It’s scheduled for the first Friday of October each year going forward. It’s called the URC DX RTTY Contest and the rules are pretty standard in that everyone works everyone. The […]

The post New RTTY contest – Friday 4th October 2024 first appeared on QSO365.

If you are of a certain age, you started with something like WordStar (or WordPerfect) most likely. Well those who want to continue have built archives to keep you going: https://sfwriter.com/blog/?p=5806 Anyone can have WordStar for DOS 7.0 up and running on a Windows computer in a matter of minutes using this archive; with just… Continue reading Blast from the Past – WordStar 7.0 Archive

Remember yesterday when I mentioned the latest addition to my POTA setup, the Xiegu 5105 QRP rig….

Well this morning I decided to test it out and see how much work I would have to do with setting the parameters such as mic gain, processor, to make it sound like me… I was also testing out my EARCHI 9:1 unun with a 29.5 foot random wire to see how it would play with the built in AT of the 5105.

I figured I might as well do the testing at a POTA location just in case I was able to turn the test into an activation.

For this I chose Fort Frontenac POTA CA-5303. Its fairly easy to get there via the Kingston Transit system and its also close to downtown and all the amenities I might need. In the North East corner of the picture you will notice some white lines on the ground.

They are actually the walls of what’s left of that part of the Fort. Also the only parts of the Historic Site that is open to the public.

I leaned my MFJ 33 foot mast (supporting the 9:1 and wire in the vertical configuration) up against the tree.

And then ran the COAX over to the remains of the wall and set up my radio there and started operating.

My first contact was on 7.255 with the NCS of the ECARS net. He did hear me and considering I was QRP I was pleased. He did tell me that my audio seemed hot as if I was overdriving things. Lowering my voice seemed to help.

After that I looked at POTA Spots and managed to get W2IDG and VE3FI into the log from their parks and then finished up with the NCS of the MidCars net on 7.258.. All contacts were made on 40m SSB. I tried 20 SSB and was hearing lots of stations including a POTA Activation in VO1 but no luck breaking any of the pileups.

Then I figured it was time to get home and try to re configure the radio to my liking… I turned off the Speech Processor and lowered the Mic Gain from 60 to 40. Over the next few days I will get out again and see what else I have to do to get things sounding right.

Till then

73bob

People who know me have heard me say that after all these years there are 3 radios I have sold that I actually regret selling. Well now there are only 2 radios that I regret selling…

.

Welcome the Xiegu X5105 back into my portable shack…

.

Between my FT991a and my FT891 there was a bit of a gap. The Yeasu FT891 Portable Station was a bit too heavy for my old bones. I needed something in a lighter backpack to make it easier to carry if I was to choose to activate one of the local POTA Parks here in Kingston.

The above pic shows my old X5105 with the Bandspringer attached

The Xiegu X5105 fills that gap. With the built in battery pack, the built in automatic antenna tuner along with the contest keyer and the built in CW Decoder it makes it a dream portable station.

My antennas are a 40m EFHW made with 28ga wire and a QRP AMAZON 49:1 unun. I also can use a 29foot end fed random wire using a QRP EARCHI 9:1 unun.

I also have the SOTABeams Bandspringer antenna that plugs right into the antenna input and uses the built in tuner to operate between 10m and 60m.

So what’s the other two radios you might ask?

Above is my first QRP setup. FT817, LDG QRP Autotuner.

If I could work a deal for a Yaesu FT817 and a Flex 1500 it would complete the list. However used rigs are pricy and it seems most hams think that radios seem to appreciate with age so like I mentioned above it has to be a good deal for both the seller and myself.

73bob

Everyone likes to think good about themselves, especially those who serve in the armed forces. Stories tend to be embellished over time –  Ten mile forced marches carrying that M-60 become Twenty mile hikes carrying several weapon systems after those stories are retold too many times. Some of the inflated things are cute. But when […]

Time to replace several lengths of coax and run new… 100m ought to do it!

People who know me have heard me say that after all these years there are 3 radios I have sold that I actually regret selling. Well now there are only 2 radios that I regret selling…

.

Welcome the Xiegu X5105 back into my portable shack…

.

Between my FT991a and my FT891 there was a bit of a gap. The Yeasu FT891 Portable Station was a bit too heavy for my old bones. I needed something in a lighter backpack to make it easier to carry if I was to choose to activate one of the local POTA Parks here in Kingston.

The above pic shows my old X5105 with the Bandspringer attached

The Xiegu X5105 fills that gap. With the built in battery pack, the built in automatic antenna tuner along with the contest keyer and the built in CW Decoder it makes it a dream portable station.

My antennas are a 40m EFHW made with 28ga wire and a QRP AMAZON 49:1 unun. I also can use a 29foot end fed random wire using a QRP EARCHI 9:1 unun.

I also have the SOTABeams Bandspringer antenna that plugs right into the antenna input and uses the built in tuner to operate between 10m and 60m.

So what’s the other two radios you might ask?

Above is my first QRP setup. FT817, LDG QRP Autotuner.

If I could work a deal for a Yaesu FT817 and a Flex 1500 it would complete the list. However used rigs are pricy and it seems most hams think that radios seem to appreciate with age so like I mentioned above it has to be a good deal for both the seller and myself.

73bob

Everyone likes to think good about themselves, especially those who serve in the armed forces. Stories tend to be embellished over time –  Ten mile forced marches carrying that M-60 become Twenty mile hikes carrying several weapon systems after those stories are retold too many times. Some of the inflated things are cute. But when… Continue reading A bit about Stolen Valor

I finally got some wire in the air. Well, not very much and not very high, but at least it is outside. One end is attached to an eye bolt outside the shack window positioned so I can reach it with the window open wide. From there the wire runs down to the workshop. I am not exactly sure of the length, Google Maps suggests just short of 30 feet. So pretty short! But it works, and the FT450D internal tuner can cope with it from 30m to 6m, except for 12m. Anything lower than 30m has SWR approaching 3 but otherwise it seems to be ok. Pity the sun is being naughty right now but it gets a good spread across much of Europe on 20m.

The wire feeds a 9:1 (I think!) unun and a 1:1 choke, then RG58 (*) to the patch panel. The cable needs to be routed yet as it is currently just running through the open window.

Signals received are definitely stronger than with the loft wire and Z11 tuner but it is hard to say exactly how much because of the time taken to swap leads, disable or enable the internal tuner, and tune the wire during which time the watched FT8 QSOs have ended and moved etc. However, with the TS2000X on and connected to the loft wire a random Italian FT8 signal was -17 on the TS2000X + loft wire and -9 on the FT450D + new external wire. Plus the waterfall on the two rigs definitely shows the advantage of the external wire. In fact, the wire length is probably similar to the existing loft wire.

So now I really must get round to running a wire up the garden which will be a lot longer.

(* Typical. I put RB58 instead of RG58, didn’t proof read, turned everything off for work and just got back to edit it now!)

Here is a summary of the news trending This Week in Amateur Radio. This week's edition is anchored by Chris Perrine, KB2FAF, Dave Wilson, WA2HOY, Rich Lawrence, KB2MOB, Don Hulick, K2ATJ, Joshua Marler, AA4WX, Marvin Turner, W0MET, Eric Zittel, KD2RJX, Will Rogers, K5WLR, Denny Haight, NZ8D, George Bowen, W2XBS, and Jessica Bowen, KC2VWX.

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Last night around 9pm I was browsing Amazon and found the same 64:1 unun that I use with my 40m EFHW. This antenna is my primary antenna for my “Transportable/POTA” setup with my FT891.

I decided that the last one worked so well for me that it was time to see if the 1st one was the real deal or a fluke.

Around noon today I checked my front door and found the Amazon Fairy had magically made the new 64:1 unun appear sometime between 10am (last time I checked for it) and noon.

I had a spare 100 foot roll of Princess Auto 18ga insulated wire in the shack and as a bonus for my home environment is was even green.

I quickly measured out 64 feet and then did the connection things. As with most of Eastern North America it was a rather wet day.

Around 4pm locally the rain stopped and I was able to remove the old wire and install the new antenna, once again using the fir trees on the edge of my yard for camo as not draw attention to the antenna.

The SWR is pretty good especially for a wire hidden in the branches:

6m – 2.5:1, 10m – 1.7:1, 12m- 1.2:2, 15m – 1.6:1

20m – 2.0:1, 40m – 1.3:1, 80m – 3.0:1

The bands are not the best, but signal reports (90w output pwr) were fairly well (S7-S9+) with the stations that I was able to contact.

All in all for what it is…. I’m impressed and the best part is that using the built in auto tuner on my Yaesu FT991a I can easily bring it down to 1:1 on all the bands listed above.

The results are the same on my Yaesu FT891 with the same style of balun and a 64 foot length of quality (Red) Princess Auto 18 ga automotive wire. The only real difference is that as I use the 891 with no tuner I have to be careful on some of the bands.

As the new install gets more use I will let you know if there are any “issues” with its performance.

73bob

Last night around 9pm I was browsing Amazon and found the same 64:1 unun that I use with my 40m EFHW. This antenna is my primary antenna for my “Transportable/POTA” setup with my FT891.

I decided that the last one worked so well for me that it was time to see if the 1st one was the real deal or a fluke.

Around noon today I checked my front door and found the Amazon Fairy had magically made the new 64:1 unun appear sometime between 10am (last time I checked for it) and noon.

I had a spare 100 foot roll of Princess Auto 18ga insulated wire in the shack and as a bonus for my home environment is was even green.

I quickly measured out 64 feet and then did the connection things. As with most of Eastern North America it was a rather wet day.

Around 4pm locally the rain stopped and I was able to remove the old wire and install the new antenna, once again using the fir trees on the edge of my yard for camo as not draw attention to the antenna.

The SWR is pretty good especially for a wire hidden in the branches:

6m – 2.5:1, 10m – 1.7:1, 12m- 1.2:2, 15m – 1.6:1

20m – 2.0:1, 40m – 1.3:1, 80m – 3.0:1

The bands are not the best, but signal reports (90w output pwr) were fairly well (S7-S9+) with the stations that I was able to contact.

All in all for what it is…. I’m impressed and the best part is that using the built in auto tuner on my Yaesu FT991a I can easily bring it down to 1:1 on all the bands listed above.

The results are the same on my Yaesu FT891 with the same style of balun and a 64 foot length of quality (Red) Princess Auto 18 ga automotive wire. The only real difference is that as I use the 891 with no tuner I have to be careful on some of the bands.

As the new install gets more use I will let you know if there are any “issues” with its performance.

73bob

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 –

FREQUENCY (MHz)	INSERTION LOSS (dB)
30	0
20	0.1
15	0.25
10	0.5
3.7	1
3	3
1.7 (1700 KHz)	41
1.5 (1500 KHz)	49

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 –

FREQUENCY (MHz)	INSERTION LOSS (dB)
30	0
20	0.04
15	0.12
10	0.25
3.7	0.82
2.8	3
1.7 (1700 KHz)	40
1.5 (1500 KHz)	48

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 –

FREQUENCY (MHz)	INSERTION LOSS (dB)
30	0
20	0.1
15	0.25
10	0.5
3.7	1
3	3
1.7 (1700 KHz)	41
1.5 (1500 KHz)	49

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 –

FREQUENCY (MHz)	INSERTION LOSS (dB)
30	0
20	0.04
15	0.12
10	0.25
3.7	0.82
2.8	3
1.7 (1700 KHz)	40
1.5 (1500 KHz)	48

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.

Anyone who chases DX can’t fail to have noticed that the Jarvis Island DXpedition is now on air and has been for less than 48 hours. I did have a listen yesterday but didn’t hear them anywhere. I set up HamAlert notifications specifically for N5J with the source set as G, GM and GW in […]

The post That’s N5J in the log for DXCC #304 first appeared on QSO365.

New (to me) arrival in the shack… something I’ve been toying with getting for some time now. This is a TS2000X and has the 1296MHz option installed. It will take me a little while to get acquainted with it but it brings more capability on 2m and 70cm and adds 1296. I’ve been using an FT817 on VHF for FT8 etc. up until now and generally running it at 2.5W – fun, but I wanted a bit more juice up there.

The Signalink from the ‘817 is ready to go, just waiting for a CAT cable and some coax plugs as I’ve used all the ones I need. That will at least give me time to read about the rig before playing…

Life has its own schedules and own demands.  Peacefully with family in attendance my mother died and we are in the midst of the funeral planning and execution, along with the dozens of other things that need to be done. Even when a death is gradual and gentle, there is that shaken reality when it […]