Many thanks to SWLing Post contributor, Matt Blaze (WB2SRI), for sharing another brilliant audio comparison featuring benchmark portable radios:
Medium wave selectivity shootout
by Matt Blaze
I did another monster medium wave portable receiver comparison, this time with the aim of comparing receivers’ ability to deal with weak signals in the presence of strong adjacent channels.
Once again, I went up to the roof with eight MW portables with built-in antennas and recorded them simultaneously along with my “reference signal”, from an Icom R-9500 with an active loop on the roof. As before, I recorded a narrated stereo mix with the Icom on the left and the rotation of radios for a minute or two each on the right, but have “solo” tracks available for the full time for each radio. The nine receivers in the lineup this time included:
Icom R-9500 (with amplified Wellbrook loop antenna on roof)
Potomac Instruments FIM-41 Field Intensity Meter (my personal favorite)
C.Crane Radio 2E
I recorded two signals, one at night and one during the day.
The first was at night: WWL New Orleans on 870 KHz. This signal is usually weak to medium strength here, but is a challenge for two reasons: first, it shares the frequency with Cuba’s Radio Reloj, and it is squeezed between two much higher strength signals: Toronto’s CJBC on 860, and NYC’s WCBS on 880. So you need a decent receiver and careful antenna orientation to receive it well here. That said, everything did pretty well, though you can see that some radios did better than others.
Potomac Instruments FIM-41 Field Intensity Meter
C.Crane Radio 2E
The second signal was during the day and was MUCH more marginal: WRJR Claremont, VA on 670 KHz. This was real challenge for any receiver and antenna. The signal was weak, and overshadowed by WCBM Baltimore on 680, a 50KW daytimer that is very strong here. (I’m not 100% sure that we were actually listening to WRJR – I never got an ID, but the station format and signal bearing was right). We can really hear some differences between the radios here.
Potomac Instruments FIM-41 Field Intensity Meter
C.Crane Radio 2E
Everything (except the Icom) was powered by batteries and used the internal MW wave antenna, oriented for best reception by ear (not just maximizing signal strength, but also nulling any interference). The loop for the Icom was similarly oriented for best intelligibility.
For audio nerds: The recording setup involved a lot of gear, but made it fairly easy to manage capturing so many inputs at once. The portable radios were all connected to a Sound Devices 788T recorder, with levels controlled by a CL-9 linear mixing board control surface. This both recorded the solo tracks for the portables as well as providing a rotating mix signal for each receiver that was sent to the next recorder in the chain, a Sound Devices 833. The 833 received the mix audio from the 788T, which went directly to the right channel. The left channel on the 833 got audio from a Lectrosonics 822 digital wireless receiver, which had the feed from the Icom R-9500 in the shack (via a Lectrosonics DBu transmitter). The center channel on the 833 for narration of the mix, which I did with a Coles 4104B noise-canceling ribbon mic. This let me record fairly clean audio in spite of a fairly noisy environment with some wind.
All the radio tracks were recorded directly off the radios’ audio line outputs, or, if no line out was available, from the speaker/headphone jack through a “direct box” interface. I tried to make the levels as close to equal as I could, but varied band conditions and different receiver AGC characteristics made it difficult to be completely consistent.
Making the recordings was pretty easy once it was set up, but it did involve a turning a lot of knobs and moving faders in real time. I must have looked like some kind of mad scientist DJ to my neighbors, some of whom looked at me oddly from their own roofs.
Happy Thanksgiving weekend!
Thank you, Matt, for another brilliant audio comparison! I appreciate the attention and care you put into setting up and performing these comparisons–not an easy task to say the least. That Potomac Instruments FIM-41 is an impressive machine!
By the way, I consider it a badge of honor when the neighbors look at me as if I’m a mad scientist. I’m willing to bet this wasn’t your first time! 🙂
Post readers: If you like this audio comparison, please check out Matt’s previous posts as well:
I was recently asked to make a table comparing the basic features and specifications of the new Xiegu GSOC/G90 combo, and comparing it with the Icom IC-7300 and IC-705.
This is by no means a comprehensive list, and I plan to add to it as I test the GSOC. It doesn’t include some of the digital mode encoding/decoding features yet. I’m currently waiting for the next GSOC firmware upgrade (scheduled for November 20, 2020) before I proceed as it should add mode decoding, audio recording, fix CW mode latency, and add/fix a number of other items/issues.
Click to enlarge
Quick summary of comparison
At the end of the day, these radios are quite different from each other. Here’s a quick list of obvious pros and cons with this comparison in mind:
Xiegu GSOC G90 combo ($975 US)
The GSOC’s 7″ capacitive touch screen is the biggest of the bunch
The GSOC can be paired with the G90 or X5101 transceivers (see cons)
The GSOC controller is connected to the transceiver body via a cable, thus giving more options to mount/display in the shack
The G90 transceiver (read review) is a good value and solid basic transceiver
Upgradability over time (pro) though incomplete at time of posting (con)
GSOC can be detached, left at home, and G90 control head replaced on G90 body to keep field kit more simple (see con)
The GSCO is not stand-alone and must be paired with a Xiegu transceiver like the Xiegu G90 or X5105. The X5105 currently has has limited functionality with the GSOC but I understand this is being addressed. (see pro)
I don’t believe the GSOC can act as a sound card interface if directly connected with a computer (I will correct this if I discover otherwise). This means, for digital modes, you may still require an external sound card interface
No six meter coverage like the IC-7300 and IC-705
Quite a lot of needed cables and connections if operating multiple modes; both GSOC and G90 require separate power connections
At time of posting, a number of announced features missing in early units, but this should be addressed with a Nov 20, 2020 firmware upgrade
Replacing and removing G90 control head requires replacing four screws to hold in side panels and secure head to transceiver body (see pro)
Icom IC-7300 ($1040 US)
Built-in sound card interface for for easy digital mode operation
Well thought-through ergonomics, but on that of the IC-7300
Includes six meters and VHF/UHF multi-mode operation with high frequency stability
Includes D-Star mode
Includes wireless LAN, Bluetooth, and built-in GPS
Weighs 2.4 lbs/1.1 kg (lightest and most portable of the bunch)
No internal ATU option
Maximum of 10 watts of output power
The priciest of this bunch at $1300 US
In short, I’d advise those looking for a 100 watt radio, to grab the Icom IC-7300 without hesitation. It’s a solid choice.
If you’re looking for the most portable of these options, are okay with 10 watts of maximum output power, and don’t mind dropping $1300 on a transceiver, the Icom IC-705 is for you. You might also consider the Elecraft KX3, Elecraft KX2, and lab599 Discovery TX-500 as field-portable radios. None of them, however, sport the IC-705 display, nor do they have native VHF/UHF multimode operation (although there is a limited KX3 2M option). The IC-705 is the only HF QRP radio at present that also has LAN, Bluetooth, and built-in GPS. And, oh yes, even D-star.
If you’re a fan of the Xiegu G90 or already own one, give the GSOC controller some consideration. It offers a more “modular” package than any of the transceivers mentioned above in that the controller and G90 faceplace can be swapped on the G90 body. The GSOC screen is also a pleasure since there are two USB ports that can connect a mouse and keyboard (driver for mine were instantly recognized by the OS). The GSOC/G90 combo is a bit “awkward” in that a number of cables and connections are needed when configured to operate both SSB and CW: a CW key cable, Microphone cable, I/Q cable, serial control cable, power cable for the GSOC, and a power cable for the G90. This doesn’t include the cables that might be needed for digital operation. I dislike the fact that the CW cable can only be plugged into the transceiver body instead of the GSOC controller like the microphone. Still: this controller adds functionality to the G90 (including FM mode eventually) that may be worth the investment for some.
Did I miss something?
I’ll update this list with any obvious pros/cons I may have missed–please feel free to comment if you see a glaring omission! Again, these notes are made with a comparison of these three models in mind, not a comprehensive review of each. I hope this might help others make a purchase decision.
Well, not pocket change for most people, but I couldn’t pass up a clever headline!
I want to alert SWLing Post readers to a lower cost option for the new BELKA-DX than the Mobimax source: the ecommerce web site of Alex Buevky (EU1ME) who designed the radio.
In early February I bought the original BELKA DSP from the designer’s site, for a total of $117 USD. It arrived safely in 10 days to my Washington State address, with free tracked shipping included.
Yesterday I ordered the new BELKA-DX from the same web site, and the grand total was 340 BYN, or in US Dollars, $128, tracked shipping included.
If I had ordered from Mobimax, the total would have been 176.91 Euro, or $205.76 USD. That price includes FedEx shipping, the only available option to the USA.
Purchasing from the BELKA-DX designer’s web site in Belarus saved me nearly $78, and I’m confident I’ll receive this new model in about a week and a half as before (hopefully no COVID-19 related delays).
I had no issues this time or previously with my payment being “flagged” for security concerns. I used my PayPal VISA card and the transaction completed without issues.
For more information on this tiny powerhouse receiver, see Georges Ringotte’s (F6DFZ) brief review here on the SWLing Post.
Guy Atkins is a Sr. Graphic Designer for T-Mobile and lives near Seattle, Washington. He’s a regular contributor to the SWLing Post.
I see more and more videos of the PL-330 popping up on YouTube. I’m wondering what firmware they run. It’s easy to identify the firmware version.
Press and hold the VM/VF button when the radio is off. Release the button when all icons are displayed. Next, the display will briefly show the firmware version in the upper right corner. As you can see in the picture (above), mine has version 3302.
Thanks so much for the tip, Jaap! I am curious, too, if Tecsun is updating the firmware version with each release/update of the PL-330. With the PL-880, there were a number of iterations all carrying the same version number (8820, if memory serves).
It would be great for comparison purposes to check the firmware number.
The seller, who lives about 2 hours from my QTH, described his KX1 as the full package: a complete 3 band (40/30/20M) KX1 with all of the items needed to get on the air (save batteries) in a Pelican 1060 Micro Case.
The KX1 I owned in the past was a four bander (80/40/30/20M) and I already double checked to make sure Elecraft still had a few of their 80/30 module kits available (they do!). I do operate 80M in the field on occasion, but I really wanted the 80/30 module to get full use of the expanded HF receiver range which allows me to zero-beat broadcast stations and do a little SWLing while in the field.
The seller shipped the radio that same afternoon and I purchased it for $300 (plus shipping) based purely on his good word.
The KX1 package
I’ll admit, I was a bit nervous: I hadn’t asked all of the typical questions about dents/dings, if it smelled of cigarette smoke, and hadn’t even asked for photos. I just had a feeling it would all be good (but please, never follow my example here–I was drunk with excitement).
Here’s the photo I took after removing the Pelican case from the shipping box and opening it for the first time:
My jaw dropped.
The seller was right: everything I needed (and more!) was in the Pelican case with the KX1. Not only that, everything was labeled. An indication that the previous owner took pride in this little radio.
I don’t think the seller actually put this kit together. He bought it this way two years ago and I don’t think he ever even put it on the air based on his note to me. He sold the KX1 because he wasn’t using it.
I don’t know who the original owner was, but they did a fabulous job not only putting this field kit together, but also soldering/building the KX1. I hope the original owner reads this article sometime and steps forward.
You might note in the photo that there’s even a quick reference sheet, Morse Code reference sheet and QRP calling frequencies list attached to the Pelican’s lid inside. How clever!
I plan to replace the Morse Code sheet with a list of POTA and SOTA park/summit references and re-print the QRP calling frequencies sheet. But other than that, I’m leaving it all as-is. This might be the only time I’ve ever purchased a “package” transceiver and not modified it in some significant way.
Speaking of modifying: that 80/30 meter module? Glad I didn’t purchase one.
After putting the KX1 on a dummy load, I checked each band for output power. Band changes are made on the KX1 by pressing the “Band” button which cycles through the bands one-way. It started on 40 meters, then on to 30 meters, and 20 meters. All tested fine. Then I pressed the band button to return to 40 meters and the KX1 dived down to the 80 meter band!
Turns out, this is a four band KX1! Woo hoo! That saved me from having to purchase the $90 30/80M kit (although admittedly, I was looking forward to building it).
The only issue with the KX1 was that its paddles would only send “dit dah” from either side. I was able to fix this, though, by disassembling the paddles and fixing a short.
Although I’m currently in the process of testing the Icom IC-705, I’ve taken the KX1 along on a number of my park adventures and switched it out during band changes.
Indeed, my first two contacts were made using some nearly-depleted AA rechargeables on 30 meters: I worked a station in Iowa and one in Kansas with perhaps 1.5 watts of output power–not bad from North Carolina!
I’m super pleased to have the KX1 back in my field radio arsenal.
I name radios I plan to keep for the long-haul, so I dubbed this little KX1 “Ruby” after one of my favorite actresses, Barbara Stanwyck.
Look for Ruby and me on the air at a park or summit near you!
Many thanks to SWLing Post contributor, 13dka, who shares the following guest post:
Gone fishing…for DX: Reception enhancement at the seaside
In each of my few reviews I referred to “the dike” or “my happy place”, which is a tiny stretch of the 380 miles of dike protecting Germany’s North Sea coast. This is the place where I like to go for maximum listening pleasure and of course for testing radios. Everyone knows that close proximity to an ocean is good for radio reception…but why is that? Is there a way to quantify “good”?
Of course there is, this has been documented before, there is probably lots of literature about it and old papers like this one (click here to download PDF). A complete answer to the question has at least two parts:
1. Less QRM
It may be obvious, but civilization and therefore QRM sources at such a place extend to one hemisphere only, because the other one is covered with ocean for 100s, if not 1000s of miles. There are few places on the planet that offer such a lack of civilization in such a big area, while still being accessible, habitable and in range for pizza delivery. Unless you’re in the midst of a noisy tourist trap town, QRM will be low. Still, you may have to find a good spot away from all tourist attractions and industry for absolutely minimal QRM.
My dike listening post is far enough from the next small tourist trap town (in which I live) and also sufficiently far away from the few houses of the next tiny village and it’s located in an area that doesn’t have HV power lines (important for MW and LW reception!) or industrial areas, other small villages are miles away and miles apart, the next town is 20 km/12 miles away from there. In other words, man-made noise is just not an issue there.
That alone would be making shortwave reception as good as it gets and it gives me an opportunity to check out radios on my own terms: The only way to assess a radio’s properties and qualities without or beyond test equipment is under ideal conditions, particularly for everything that has to do with sensitivity. It’s already difficult without QRM (because natural noise (QRN) can easily be higher than the receiver’s sensitivity threshold too, depending on a number of factors), and even small amounts of QRM on top make that assessment increasingly impossible. This is particularly true for portables, which often can’t be fully isolated from local noise sources for a couple of reasons.
Yes, most modern radios are all very sensitive and equal to the degree that it doesn’t make a difference in 98% of all regular reception scenarios but my experience at the dike is that there are still differences, and the difference between my least sensitive and my most sensitive portable is not at all negligible, even more because they are not only receivers but the entire receiving system including the antenna. You won’t notice that difference in the middle of a city, but you may notice it in the woods.
When the radio gets boring, I can still have fun with the swing and the slide!
2. More signal
I always had a feeling that signals actually increase at the dike and that made me curious enough to actually test this by having a receiver tuned to some station in the car, then driving away from the dike and back. Until recently it didn’t come to me to document or even quantify this difference though. When I was once again googling for simple answers to the question what the reason might be, I stumbled upon this video: Callum (M0MCX) demonstrating the true reason for this in MMANA (an antenna modeling software) on his “DX Commander” channel:
To summarize this, Callum explains how a pretty dramatic difference in ground conductivity near the sea (click here to download PDF) leads to an increase in antenna gain, or more precisely a decrease in ground return losses equaling more antenna gain. Of course I assumed that the salt water has something to do with but I had no idea how much: For example, average ground has a conductivity of 0.005 Siemens per meter, salt water is averaging at 5.0 S/m, that’s a factor of 1,000 (!) and that leads to roughly 10dB of gain. That’s right, whatever antenna you use at home in the backcountry would get a free 10dB gain increase by the sea, antennas with actual dBd or dBi gain have even more gain there.
That this has a nice impact on your transmitting signal should be obvious if you’re a ham, if not just imagine that you’d need a 10x more powerful amplifier or an array of wires or verticals or a full-size Yagi to get that kind of gain by directionality. But this is also great for reception: You may argue that 10dB is “only” little more than 1.5 S-units but 1.5 S-units at the bottom of the meter scale spans the entire range between “can’t hear a thing” and “fully copy”!
A practical test
It’s not that I don’t believe DX Commander’s assessment there but I just had to see it myself and find a way to share that with you. A difficulty was finding a station that has A) a stable signal but is B) not really local, C) on shortwave, D) always on air and E) propagation must be across water or at least along the shoreline.
The army (or navy) to the rescue! After several days of observing STANAG stations for their variation in signal on different times of the day, I picked one on 4083 kHz (thanks to whoever pays taxes to keep that thing blasting the band day and night!). I don’t know where exactly (my KiwiSDR-assisted guess is the English channel region) that station is, but it’s always in the same narrow range of levels around S9 here at home, there’s usually the same little QSB on the signal, and the signals are the same day or night.
On top of that, I had a look at geological maps of my part of the country to find out how far I should drive into the backcountry to find conditions that are really different from the coast. Where I live, former sea ground and marsh land is forming a pretty wide strip of moist, fertile soil with above average conductivity, but approximately 20km/12mi to the east the ground changes to a composition typical for the terminal moraine inland formed in the ice age. So I picked a quiet place 25km east of my QTH to measure the level of that STANAG station and also to record the BBC on 198 kHz. Some source stated that the coastal enhancement effect can be observed within 10 lambda distance to the shoreline, that would be 730m for the 4 MHz STANAG station and 15km for the BBC, so 25km should suffice to rule out any residue enhancement from the seaside.
My car stereo has no S-meter (or a proper antenna, so reception is needlessly bad but this is good in this case) so all you get is the difference in audio. The car had the same orientation (nose pointing to the east) at both places. For the 4 MHz signal though (coincidence or not), the meter shows ~10dBm (or dBµV/EMF) more signal at the dike.
3. Effect on SNR
Remember, more signal alone does not equal better reception, what we’re looking for is a better signal-to-noise ratio (SNR). Now that we’ve established that the man-made noise should be as low as possible at “my” dike, the remaining question is: Does this signal enhancement have an effect on SNR as well? Even if there is virtually no local QRM at my “happy place” – there is still natural noise (QRN) and that wouldn’t that likely gain 10dB too?
Here are some hypotheses that may be subject of debate and some calculations way over my head (physics/math fans, please comment and help someone out who always got an F in math!). Sorry for all the gross oversimplifications:
Extremely lossy antennas
We know that pure reception antennas are often a bit different in that the general reciprocity rule has comparatively little meaning, many antennas designed for optimizing reception in specific situations would be terrible transmitting antennas. One quite extreme example, not meant to optimize anything but portability is the telescopic whip on shortwaves >10m. At the dike, those gain more signal too. When the QRN drops after sunset on higher frequencies, the extremely lossy whip might be an exception because the signal coming out of it is so small that it’s much closer to the receiver noise, so this friendly signal boost could lift very faint signals above the receiver noise more than the QRN, which in turn could mean a little increase in SNR, and as we know even a little increase in SNR can go a long way.
The BBC Radio 4 longwave recording is likely another example for this – the unusually weak signal is coming from a small and badly matched rubber antenna with abysmal performance on all frequency ranges including LW. The SNR is obviously increasing at the dike because the signal gets lifted more above the base noise of the receiving system, while the atmospheric noise component is likely still far below that threshold. Many deliberately lossy antenna design, such as flag/tennant, passive small aperture loops (like e.g. the YouLoop) or loop-on-ground antennas may benefit most from losses decreasing by 10dB.
Not so lossy antennas, polarization and elevation patterns
However, there is still more than a signal strength difference between “big” antennas and the whips at the dike: Not only at the sea, directionality will have an impact on QRN levels, a bidirectional antenna may already decrease QRN and hence increase SNR further, an unidirectional antenna even more, that’s one reason why proper Beverage antennas for example work wonders particularly on noisy low frequencies at night (but this is actually a bad example because Beverage antennas are said to work best on lossy ground).
Also, directional or not, the “ideal” ground will likely change the radiation pattern, namely the elevation angles, putting the “focus” of the antenna from near to far – or vice versa: As far as my research went, antennas with horizontal polarization are not ideal in this regard as they benefit much less from the “mirror effect” and a relatively low antenna height may be more disadvantageous for DX (but maybe good for NVIS/local ragchewing) than usual. Well, that explains why I never got particularly good results with horizontal dipoles at the dike!
Using a loop-on-ground antenna at a place without QRM may sound ridiculously out of place at first, but they are bidirectional and vertically polarized antennas, so the high ground conductivity theoretically flattens the take-off angle of the lobes, on top of that they are ~10dB less lossy at the dike, making even a LoG act more like something you’d string up as high as possible elsewhere. They are incredibly convenient, particularly on beaches where natural antenna supports may be non-existent and I found them working extremely well at the dike, now I think I know why. In particular the preamplified version I tried proved to be good enough to receive 4 continents on 20m and a 5th one on 40m – over the course of 4 hours on an evening when conditions were at best slightly above average. Though the really important point is that it increased the SNR further, despite the QRN still showing up on the little Belka’s meter when I connected the whip for comparison (alas not shown in the video).
The 5th continent is missing in this video because the signals from South Africa were not great anymore that late in the evening, but a recording exists.
Here’s a video I shot last year, comparing the same LoG with the whip on my Tecsun S-8800 on 25m (Radio Marti 11930 kHz):
At the same time, I recorded the station with the next decent KiwiSDR in my area:
Of course, these directionality vs noise mechanisms are basically the same on any soil. But compensating ground losses and getting flat elevation patterns may require great efforts, like extensive radial systems, buried meshes etc. and it’s pretty hard to cover enough area around the antenna (minimum 1/2 wavelength, ideally more!) to get optimum results on disadvantaged soils, while still never reaching the beach conditions. You may have to invest a lot of labor and/or money to overcome such geological hardships, while the beach gives you all that for free.
But there may be yet another contributing factor: The gain pattern is likely not symmetrical – signals (and QRN) coming from the land side will likely not benefit the same way from the enhancement, which tapers off quickly (10 wavelengths) on the land side of the dike and regular “cross-country” conditions take place in that direction, while salt water stretching far beyond the horizon is enhancing reception to the other side.
So my preliminary answer to that question would be: “Yes, under circumstances the shoreline signal increase and ground properties can improve SNR further, that improvement can be harvested easily with vertically polarized antennas”.
Would it be worthwhile driving 1000 miles to the next ocean beach… for SWLing?
Maybe not every week–? Seriously, it depends.
Sure, an ocean shoreline will generally help turning up the very best your radios and antennas can deliver, I think the only way to top this would be adding a sensible amount of elevation, a.k.a. cliff coasts.
If you’re interested in extreme DX or just in the technical performance aspect, if you want to experience what your stuff is capable of or if you don’t want to put a lot of effort into setting up antennas, you should definitely find a quiet place at the ocean, particularly if your options to get maximum performance are rather limited (space constraints, QRM, HOA restrictions, you name it) at home.
If you’re a BCL/program listener and more interested in the “content” than the way it came to you, if you’re generally happy with reception of your favorite programs or if you simply have some very well working setup at home, there’s likely not much the beach could offer you in terms of radio. But the seaside has much more to offer than fatter shortwaves of course.
From left to right: Starry sky capture with cellphone cam, nocticlucent clouds behind the dike, car with hot coffee inside and a shortwave portable suction-cupped to the side window – nights at the dike are usually cold but sometimes just beautiful. (Click to enlarge.)
However, getting away from the QRM means everything for a better SNR and best reception. In other words, if the next ocean is really a hassle to reach, it may be a better idea to just find a very quiet place nearby and maybe putting up some more substantial antenna than driving 1000 miles. But if you happen to plan on some seaside vacation, make absolutely sure you bring two radios (because it may break your heart if your only radio fails)!
I discovered several features that are not displayed on the keyboard both on the Internet and by fiddling with the radio. Maybe these features are in the Chinese manual but I simply can’t read that language. What became clear is that the PL-330 resembles the PL-990x. But I couldn’t find if DNR and Muting Threshold are supported in the firmware I have (3302). Here is a table with the features and how to operate: