Category Archives: Shortwave Radio Reviews

Tecsun PL-990x vs. PL-880: Comparing SSB audio characteristics and pre-production/production PL-990 models

A number of SWLing Post readers have been asking about SSB audio characteristics on the new Tecsun PL-990.

Earlier this week, I took a moment while visiting family to make a few quick comparison videos with the PL-880 outdoors and away from RFI.

As I mention in the videos, there are a lot of cicadas singing in the background and you can also hear a bit of road noise–not ideal for audio, but I had to take advantage of a break in the weather!

You should also note that this isn’t a sensitivity comparison. The radios were pretty close together–if measuring sensitivity, I would have spaced them much further apart. Rather, I hope these videos give you an idea of the audio characteristics in SSB (both CW narrow and voice) and one comparison in AM. If you’re curious about sensitivity and how the PL-990x compares, check out Dan Robinsons initial evaluation.

CW Audio: .5 kHz filter on the 80 meter band

CW Audio: .5 kHz filter on the 30 meter band

SSB audio: 75 meter band

AM Audio: 5 kHz filter WWV 10 MHz

My thoughts

While these videos are far from ideal, they should give you a real-word impression of audio characteristics.

Personally, I think the PL-990x is a much better performer in single sideband. The noise floor is lower, but I think that may have more to do with better filter implementation. I’ve always felt that the PL-880 audio sounds “wider” than the selected filter in the more narrow SSB selections.

In addition, the PL-990x exhibits better SSB stability that’s especially noticeable in CW. The PL-880, at times, almost sounds garbled in comparison.

I also mentioned in the last video that the audio sounds better on the PL-880. I should have qualified that statement a bit better.

In general, yes, the PL-880 audio sounds better because its built-in speaker has slightly better audio fidelity that’s most noticeable when listening to music on the FM band, or a strong local AM station. On shortwave, I feel like I actually prefer the PL-990 audio for all but the strongest stations although I do wish the PL-990 filter could be widened to 9 kHz like the PL-880.

PL-990x (pre-production) vs. PL-990 (production model)

Tecsun Radios Australia reached out and kindly sent me one of their PL-990 production model radios to compare with the PL-990x pre-production model from Anon-Co we’ve been testing up to this point. This has been incredibly helpful as I put together my PL-990 review for the 2021 World Radio TV Handbook.

As I’ve mentioned in previous posts, I feel it can be problematic using a pre-production model radio for review only because there can be differences in quality control when a small number of pre-production units are manufactured compared with a proper first production run (remember this case?).

I’ve only had the production model PL-990 for a few days and most of that time we’ve been dealing with the remnants of hurricane Sally moving through our area dumping torrential rains.

Last night, however, a massive tree fell across our road knocking out power for the better part of 5 hours. This gave me a perfect excuse to start my comparison indoors while rain continued outside.

Based on my comparisons last night, it appears performance is nearly identical between the production and pre-production models. I’ve still more testing to do, but my initial impressions are most positive. Very happy quality appears to be consistent.

Many thanks again to Tecsun Radios Australia for making this comparison possible.

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Tecsun PL-990x Initial Assessment

SWLing Post contributor, Dan Robinson, and I have been evaluating a pre-production model of the Tecsun PL-990x portable shortwave radio–the same model which will be soon sold by Anon-Co.

Dan has just completed his initial assessment and included a long-format video. Many thanks to Dan for sharing the following:


Tecsun PL-990x:  An Initial Assessment

by Dan Robinson

Recently, Thomas Witherspoon posted the first photos of the Tecsun PL-990x – we both received units from Anon-co in Hong Kong for testing.

I was able to spend some time outside my house here in Maryland, running the 990x and comparing it to the older receiver by Tecsun, the PL-880.

Tecsun undertook a thorough re-design of the PL-880, which among other things was known for its superb sound through a large speaker.

The 880 was available both on its own, or in a hard-case kit that also included (or includes assuming these are still purchasable) a separate Tecsun-branded solid state recording device, spare knobs and other accessories including Li-ion batteries.

So, the long-awaited PL-990, which we have been seeing in YouTube videos being tested by various individuals who purchased pre-production versions from Asian sites such as AliExpress, is finally here – or will be in coming weeks and months.

Those who view my videos know that I like to do fairly long hands-on tests of receivers, and this is no exception, at about 50 minutes.  My test did not include medium wave or FM, focusing only on shortwave performance and using only the telescopic whip antenna.

Throughout the video, I do put the 990x up against the older PL-880, which had the well-known issue of poorly-implemented synchronous detection (SYNC was not an official feature in the older receiver).

IMPORTANT NOTE:   On the 990x, hitting the “4” key while the radio is powered on activates DNR (Dynamic Noise Reduction) which then activates auto-bandwidth switching, a feature I found quite annoying in the PL-880 and would no doubt find just as annoying in the 990x.  I can’t imagine why anyone would want bandwidths auto-switching on their own.

I always tell people who come to me for advice about radios that you don’t always have to have the latest receiver to enjoy what’s left of shortwave.

I am a big fan of classic older portables such as the SONY ICF SW55s, 7600GRs, SW100s, SW-07s, SW-1000Ts, SW-77s, etc along with other classics such as the Panasonic RF-B65.  I own one or more of most of these – they’re a joy to use assuming they are in good condition.

One more thing – I did not compare the 990x to the Tecsun S-8800.  I think they are really different radios – the 8800 has that gorgeous remote control and fantastic audio . . . I really don’t put it in the same category as the 880/990s or even the 600 series Tecsuns.

I will leave extensive tests of the 990x on medium wave and FM to others – there are already quite a few YouTube demonstrations online showing this.  In the tuning I did on MW and FM, the radio did seem quite sensitive.  I noted that whereas the 9 kHz bandwidth is not visible on shortwave, it is on MW.

Here is my list of high points and low points for the 990x.  Since this receiver, and the still-to-be-released H-501, may in fact be the last we will ever see from Tecsun, it’s up to the individual to make a judgment as to whether to buy.

PL-990x High Points

  • A thorough physical re-design of the old PL-880
  • Tecsun has mostly fixed the problem with synchronous mode which is now a regular as opposed to a hidden feature.
  • Selectivity options are still excellent.
  • Calibration function retained (but see below)
  • Audio is fairly full and powerful.
  • Sensitivity seems good
  • Tecsun has added mp3 play capability and a microSD slot
  • Tecsun has added bluetooth capability (NOTE:  This is activated by pressing the RADIO/MP3 key in powered off state, and then toggling Bluetooth on or off with the PLAY/PAUSE button).
  • Tuning and other knobs remain of high quality as on the PL-880
  • Bandwidths given their own separate buttons
  • Line out retained and hidden feature can adjust line out level
  • Claimed “Triple Conversion” in AM mode
  • Timer functions
  • ATS (automatic station tuning) retained
  • Nice faux-leather case retained

PL-990x negatives:

  • Re-design appears to have come at expense of speaker real estate.
  • Synchronous mode improved, but there still seems to be some distortion which is more noticeable on some frequencies and in some reception situations than others.
  • PL-880’s wide AM bandwidth of 9 kHz is no more at least on SW, but it does appear when using MW.
  • Sensitivity seems good BUT in some situations, PL-880 sounded better and seemed to bring in stations better
  • MicroSD capability does not provide recording from broadcasts (likely due to copyright issues)
  • Method for re-calibrating radio is puzzling – more information needed on this
  • Birdies are present
  • Top element of telescopic antenna is VERY thin, vulnerable to bending and breaking
  • Number keys seem to be not as good as they could be – the white paint on the keys is certain to fade over time.  On my test unit part of the “W” on the MW/LW key was already beginning to disappear.

Selectivity comparison of the PL-990x and PL-880

PL-990x

Selectivity Options on SW:

2.3, 3.5, 5.0, 6.0

Selectivity Options LSB/USB:

0.5, 1.2, 2.3, 3.0, 4.0

Selectivity Options LW/MW:

2.3, 3.5, 5.0, 9.0

PL-880

Selectivity Options SW/LW/MW:

2.3, 3.5, 5, 9

Selectivity Options LW/MW:

0.5, 1.2, 2.3, 3.0, 4.0

Video


Many thanks, Dan, for sharing your initial review with us. As always, your expertise as an experienced DXer is incredibly valuable. 

I’ve tested every function on the PL-990 save some of the hidden features (yes, there will be hidden features). Dan and I are both trying to sort out the calibration sequence so that when these units hit the market, there’ll be a documented procedure in place. 

We’ve been comparing notes along the way and are in agreement on all of the major points with this radio. Still more testing to do, but updated with be posted here with the tag: Tecsun PL-990x


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George reviews the new Tecsun PL-990

Many thanks to SWLing Post contributor, George Joachim, who shares the following review of the Tecsun PL-990.

AS George points out, the PL-990 in the following review is not the “export” model Anon-Co will eventually offer for sale later this year. It might be nearly identical in every respect, but at time of posting Tecsun is addressing some final firmware updates the the “export” version prior to starting a full first production run. As we learn more about the various versions of the PL-990 in the wild–compare serial numbers, etc.– we will eventually sort out any nuances between versions.

George purchased this PL-990 on AliExpress and I am incredibly grateful to read his review of this model:


Review of the Tecsun PL-990

by George Joachim

Introduction

The Tecsun PL 990 is one of the three new radios offered by Tecsun and according to the news from the company these may be the last developed.

The other two radios are the Tecsun H-501 and the PL-330. The H-501 is the largest with dual speakers and the PL-990 is of a similar size to the PL-880, PL-680, PL-660 and PL-600. The PL-330 is the smallest and is similar to the PL-310ET and PL-380.

The Tecsun PL-990 is a medium sized portable multi-function radio. It has the following features:

  • Shortwave (SW)
  • Medium Wave (AM)
  • Frequency Modulation (FM)
  • SSB (LSB and USB)
  • Bluetooth connectivity (BT)
  • MP3 playback from a microSD port
  • Clock and two Timers with Alarms
  • Auto Sleep
  • powered by a single 18650 rechargeable 3.7V Lithium Ion Battery, unbranded and supplied.

The radio is a refinement of the PL-880 with styling similar to the PL-680. It is matte black with a hint of grey, finished in a quality plastic case and it is ergonomic with a good weight and feel, just like the PL-880.

Background

This is my fourth portable radio of this size. I had owned the analogue Sony ICF-7601 back in the day and then the PL-660 and PL-880. The Sony was destroyed by me doing naughty electronic experiments and both the PL-660 and PL-880 were gifted to my family members.

Having no such radio, I considered the purchase of a new PL-880. I had contacted Ms Anna from the Anon Co. in HK and she was very helpful and also mentioned that Tecsun is developing a couple of new radios, but these are not yet available. This got me interested in the PL-990 and the H-501. I had also considered the H-501, because I liked the fact that it has two speaker sets, however the radio did seem a big bulky for my needs. I have a few desktop radios, but I needed something to be on my lap or by the bedside. Usually I fiddle with these portable radios lying on my chest until I find something nice to listen to then let it play on auto sleep until it puts me to sleep. I am sure some of you guys do this too. I imagine the H-501 would be a bit big for this.

After reading articles on the SWLing Post and despite the warnings about Pilot run versions and Chinese versions, I decided to risk a purchase from AliExpress. This has been my one and only purchase on AliExpress so far.

Purchase

My radio was supplied by a company called Li Jia Shops in AliExpress. It cost a steep US$400 and US$157 DHL shipping. Totally expensive and risky in my opinion, but I am known to be reckless with my online purchases.? Besides, I wanted a new toy!

As this was my first purchase from AliExpress, I was a bit apprehensive, as I mainly use eBay. Also buying electronic items from China is a bit risky. One may end up not getting the item, or getting it after some significant delay. As you all know, electronic items exported from China is the largest electronics export operation in the world, so there is congestion in logistics and Covid-19 also adds to that. Selecting DHL to ship the item was very expensive, but I believe necessary. Waiting for an expensive electronic device for two months is a painful experience, at least from my perspective. Using DHL took a mere 12 days. The main delay originated from the shippers. They give the shipment information to DHL well in advance, but they do not actually take the item to DHL unless it suits their facilitators who they assign. The shipment shows as shipped and DHL status is ‘shipment information received’, but in reality the item is still with the shippers. Once it does actually get to DHL, then it is quite fast. Usually the shippers are located in the Shenzhen area and DHL is in Hong Kong. AliExpress will not release the payment unless the buyer confirms receipt of the item as described, so there is some safety for the buyer.

Overall, I was satisfied with the purchase and shipping process. But it was expensive and it was risky. It would be better to approach Anon Co in HK for your purchases rather than AliExpress and Bangood, but ultimately it is the buyer’s decision. For the English Export Version you must wait a bit I think.

The Export Version, the Chinese Version and the Pilot Run Version

This aspect is a bit confusing. From what I understood, and I could well be wrong, the versions are as follows:

Pilot run: this has the buttons as TIME DISPLAY and ALARM (this is also slightly cheaper on AliExpress and Banggood)
Chinese version: TIME TIMER A and TIMER B, but with Chinese manuals (what I have acquired)
Export Version: TIME TIMER A and TIMER B but with English manuals. (there may be further changes / improvements, as these units are still not available)

I am not sure about the firmware. My unit is presumably a later Chinese Version. And everything works properly as per the Firmware. The serial number of my unit indicates a possible manufacture date of July 2020, although this could be wrong.

Review

The review will be based on the different functions of the radio.

FM reception

In the UAE we are blessed with several English language FM radio stations with good music and limited advertisements. Each station caters to particular tastes, such as 90s music, modern and classic hits. Reproduction was crisp and in full bodied stereo. The speaker is powerful and not unlike the speaker of the PL-880.

MW reception

I do not usually listen to AM or MW. However, the radio does a good job receiving these stations with a deep sound and minimal crackling.

SW reception

Shortwave is still out there folks, although its variety and abundance is greatly reduced. I do receive quite a few broadcasts using the telescopic antenna. Activity is concentrated around the 16m band, the 31m band and the 49m band, although occasional broadcasts can also be found in the 22m, 19m and 41m bands. The SYNC function holds on to weak broadcasts and makes them intelligible. I am sure that the Radio would do a commendable job if one could use a time machine to take it back to the SW hay-days of the 80s and 90s. I wonder if they have any time machines up for sale in AliExpress? 🙂

SSB Reception

Right out of the box I was able to fine tune into 14,182.10 kHz on the USB and hear HAMS ‘doing their thang’. It was excellent and far better than what similar attempts resulted in my previous Tecsun radios. I do think that Tecsun has improved the SSB reception with this receiver. I am not a very capable SSB chaser, but if there is something SSB out there, the PL-990 should able to pull it in. One needs to know where and when to tune and luck also plays a role.

LW Reception

Yes it is there, but no, I have never heard anything in there using the PL-990 and all my previous radios. I do wonder if submarines transmit in the LW band? I don’t know.

MP3 Playback

A lot of listeners are not interested in MP3 listening, but I am. Especially with SW being so sparse nowadays. MP3 was a feature missed from previous Tecsun radios. I enjoy compiling a list of favourite tracks and listening to them, while engaged in a barbecue or in car maintenance or cleaning. I am also a train modeler and like to listen to MP3s while running my trains. Tecsun has even supplied a Sandisk micro SD card of 16GB with various Chinese and international tracks, which I think was nice of them.

Bluetooth

There is no Bluetooth button, but by pressing the RADIO/MP3 button an indication will come on the display as BT. The radio can then be conveniently paired with a mobile phone to transfer the audio from a you tube clip or similar to the radio, although I wouldn’t see the need for that. I am not sure if files can be transferred to the radio this way, I believe the function is only for audio playback.

Presentation and packaging

Much like the PL-880, the radio comes superbly packaged. The cardboard box functions as a glossy display of the radio and its features. Inside there are foam holders and there is a sturdy grey plastic toolbox case. In the toolbox case there is the radio, within a nylon bag inside its light brown faux leather pouch. The radio as well as the pouch have a carrying strap. In the toolbox there is a black foam case that contains:

  • A blue 18650 3.7 V Lithium Ion Battery
  • A long wire antenna in its real
  • A short(ish) charging cable
  • A UK style plug adaptor
  • A Chinese style charger with 2 USB outputs
  • A Chinese language operation manual
  • A Poster containing the map of the world and country Radio codes
  • On the other side of the Poster is a detailed view of the PL-990 with illustrations in Chinese

Batteries

The radio uses one Li-Ion type 18650 3.7V battery. The included type is a blue generic unbranded type, I would have preferred a Tecsun-branded battery. I have a couple of vape equipment batteries –Golisi S30, which I believe are superior to the unbranded battery. (No, I am not a Vaper).

Concluding Remarks

The latest Tecsun offering is a great conclusion to their series of multi-function portable radios. It offers some advantages over the PL-880, such as:

  • Styling
  • MP3
  • Much improved SSB reception
  • Superb FM reproduction
  • Bluetooth

Apart from the above I don’t see a compelling reason to acquire the radio unless, SSB or MP3 is important for you. Or like me, you just must have the latest.

Score

Style: 90%
FM: 100%
SW: 90% SYNC available
SSB: 95%
MW: 85%
LW: 80%
Battery Life: 70% for the provided battery 8/10 for externally sourced batteries
Display: 70% (the display is good, but it hasn’t really changed from previous displays)
Buttons: 85% Sturdy and precise, no wobbly buttons here.
Dials: 90% hard and precise with excellent indentations
Ports: 90% strong a tight female ports with protection plugs
Packaging: 95% anything you could wish for.
Documentation: 100% for Chinese speakers
Antenna: 60% normal telescopic antenna, should be a bit more shiny IMO.
Stability: 70% Stands well and has the rear bracket as the PL-880, however, would be easy to snap if pushed.
Sensitivity: 95% if it is there it will receive it and improve the signal over listening time.

Overall Review Score:
85.3%

Final thoughts:
Go get one, if you must, but better wait for the full export version.

George Joachim
11 AUG 2020


Many thanks, George, for sharing your review of the PL-990!

So far, the PL-990 sounds like it has iterative improvements over the PL-880 which is, I suppose, what I would expect. The PL-880 is a great portable, so I believe even minor performance upgrades–especially in terms of synchronous detection–could be very beneficial to some SWLs.  And thanks for taking the deep-dive and grabbing one of the models on AliExpress! It’ll be interesting to compare notes once the “export” PL-990 is released.

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The AirSpy HF+ Discovery and a new era of portable SDR DXing

The following article first appeared in the January 2020 issue of The Spectrum Monitor magazine.


The AirSpy HF+ Discovery and a new era of portable DXing

I admit it: I used to be a bit of an old-fashioned radio curmudgeon. One of those, “I like my radios with knobs and buttons” likely followed by, “…and no other way!”

However, about fifteen years ago, many of my DXing friends started turning to the world of software defined radios (or in common parlance, “SDRs”). I staunchly opposed ever following in their footsteps. One of the reasons I for this––a good one––is that, since I spend the bulk of my day in front of a computer, why would I ever want to use a computer when I’m playing radio?

But then…gradually, I found myself playing around with a few SDRs. And I quickly learned that third-generation SDRs were capable of doing something very impressive (and fun), indeed:  making spectrum recordings.  Using this tool, I found I could record not only the audio of one individual signal, but the audio of entire swathes of radio spectrum.  And even more impressive, I learned that you could later load or “play back” the spectrum recording and tune through the bands as if in real time. Any time you want. Before long, I was hooked: SDRs had become my portal into radio time travel!

I quickly found that I loved many of the other advantages of using an SDR, as well, including visual ones––like the ability to view spectrum. The interactive interface allows one to actually see radio signals across the band in real time. I also found incredible value in waterfall displays, which show signals changing in amplitude and frequency over time. Cool stuff.

I purchased my first dedicated SDR in 2012, a WinRadio Excalibur. It was––and still is––a benchmark receiver, performing circles around my tabletop receivers and general coverage transceivers.

And today, although I own and love a number of legacy radios and still listen to them in the good old-fashioned manner to which I became accustomed, I find I’m now spending the bulk of my time DXing with SDRs.

And then, more recently, two amazing things happened in the world of SDRs. Strong market competition, together with serious innovations, have come into play. Thus, for less than $200 US, you can now purchase an SDR that would have easily cost $1,000 US only ten years ago. And now, in many cases, the $200 SDR of today will outperform the $1,000 SDR of yesteryear. We are, indeed, living in good times.

And now––no more a radio curmudgeon––I’m comfortable with my SDR-user status and time at the computer, and glad I was just curious enough about SDRs to let them into my radio (and computer) world.

Portable SDRs

Since I initially dived into the world of SDRs, I’ve tried to think of a way to take them into the field.

But first, let’s get an obvious question out of the way:

Why would you want to drag an SDR into the field, when a traditional battery-powered radio is so much easier to manage?

After all, you may say, portable and even mobile tabletop receivers require no computer, no hard drive, and are likely more reliable because there are less components to manage or to cause problems for you.

In answer, let’s look at a few scenarios where heading to the field with an SDR system might just make sense.  (Hint: Many of these reasons are rooted in the SDR’s ability to record spectrum).

Good Reason #1:  Your home location is not ideal for playing radio.

Photo by Henry Be

My good friend, London Shortwave, lives in the middle of London, England. He’s an avid radio enthusiast and DXer, but his apartment is almost a perfect storm of radio interference. Listening from his home is challenging, to say the least: he can only use indoor antennas and RFI/QRM simply inundated his local airwaves.

Many years ago, he discovered that the best way to DX was to go to an area that put urban noise and radio interference at a distance.  He found that by visiting large local parks, he could play radio with almost no RFI.

Being a computer guru, he started working on a portable SDR setup so that he could go to a park, set up an antenna, and record radio spectrum while he read a book.  His systems evolved with time, each iteration being more compact less conspicuous that the previous. Later, he could head back home, open the recorded spectrum files, and tune through these “time-shifted” recordings in the comfort of his flat. This allowed London Shortwave to maximize the low-RFI listening experience by reliving the time in the park.

Over the years, he tweaked and adapted his setup, often writing his own code to make small tablets and portable computers purpose-built portable-spectrum-capture devices. If you’re curious, you might like to read about the evolution of his systems on his blog.

Clearly, for London Shortwave, an SDR is the right way to capture spectrum and thus likely the best solution for his DX listening.

Good Reason #2:  Weak-signal workarounds.

Typically radio enthusiasts turn to field operation to work in a lower-noise environment and/or where there are no antenna restrictions, often to log new stations and DX.

SDRs afford the DXer top-shelf tools for digging weak signals out of the muck. SDR applications have advanced tools for tweaking AGC settings, synchronous detectors, filters, noise reduction, and even to tailor audio.

The WinRadio Excalibur application even includes a waterfall display which represents the entire HF band (selectable 30 MHz or 50 MHz in width)

On top of that, being able to see a swath of spectrum and waterfall gives one an easier way––a visual way––to pinpoint weak or intermittent signals. This is much harder to do with a legacy radio.

Case in point:  I like listening to pirate radio stations on shortwave. With a spectrum display, I can see when a new station may be tuning up on the band so can position the receiver to listen in from the beginning of the broadcast, and never miss a beat.

Or, in another example, the visual aspect of spectrum display means I can easily locate trans-Atlantic DX on the mediumwave bands by looking for carrier peaks on the spectrum display outside the standard North American 10 kHz spacing. The signals are very easy to spot.

Good Reason #3: DXpeditions both small and large.

Mark Fahey, scanning the bands with his WinRadio Excalibur/Surface Pro 2 combo at our 2015 PARI DXpedition

Whether you’re joining an organized DXpedition or you’re simply enjoying a little vacation DXpedition, SDRs allow you to make the most of your radio time.

Indeed, most of the organized DXpedition these days heavily incorporate the use of SDRs specifically so DXers can record spectrum. Much like example #1 above, doing this allows you to enjoy the noise-free optimal conditions over and over again through spectrum recordings. Most DXpeditioners will have an SDR making recordings while they use another receiver to DX in real time. Later, they take the recording home and dig even more weak signals out of the mix: ones that might have otherwise gone unnoticed.

Good Reason #4: Sharing the spectrum with like-minded listeners.

Earlier this year, Mark gave me this 8TB hard drive chock-full of spectrum recordings.

One of the joys I’ve discovered  in making field spectrum recordings is sharing them with fellow DXers. Most of the time when I go to shortwave radio gatherings (like the Winter SWL Fest), I take a couple hard drives to exchange with other SDR enthusiasts. My friend, Mark Fahey, and I have exchanged some of our favorite spectrum recordings this way. I give him a hard drive chock-full of terabytes of recordings, and he reciprocates. Back home (or on the train or airplane) I open one of his recordings and, boom! there I am in his shack in Freeman’s Reach, Australia, tuning through Pacific stations that are not easily heard here in North America, maybe even turning up some gems Mark himself may have overlooked…just as he is doing with my recordings from the southeast US.

I’ve also acquired DXpedition spectrum recordings this way. It’s great fun to “be there” through the recordings and to enjoy some of the benefits of being on the DXpedition in times when I couldn’t actually make it there in person. For a DXer with a consuming job, busy family life, or maybe health problems that limit their travel, an SDR recording is the way to go.

Good Reason #5: Family time

Photo by David Straight

I’m a husband and father, and no matter how much I like to play radio when we’re on vacation, my family comes first, and our family activities take priority.

Having a field-portable SDR setup means that I can arrange a “set it and forget it” spectrum capture device. Before we head out the door for a family visit, tour of the area, or a hike, I simply set my SDR to record spectrum, then listen to what I “caught” after I return, or after I’m home from vacation.

This practice has allowed me to enjoy radio as much as I like, without interrupting our family adventures. Can’t beat it!

Past challenges

With all of these benefits, one might wonder why many other DXers  haven’t been using portable SDRs in the field for a while now? That’s a good question.

Power

The WinRadio G31DDC, like many SDRs of the era, has separate data and power ports

In prior years, DXers and listeners might have been reluctant to lug an SDR and its requisite apparatus out with them. After all, it’s only been in the past decade or so that SDRs haven’t required a separate custom power supply; some legacy SDRs either required an odd voltage, or as with my WinRadio Excalibur, have very tight voltage tolerances.

Originally, taking an SDR to the field––especially in places without grid mains power––usually meant you also had to take a pricey pure sine wave inverter as well as a battery with enough capacity to run the SDR for hours on end.

Having spent many months in an off-grid cabin on the east coast of Prince Edward Island, Canada, I can confidently say it’s an ideal spot for DXing: I can erect large wire antennas there, it’s on salt water, and there are literally no locally-generated man-man noises to spoil my fun.  Of course, anytime we go to the cottage, I record spectrum, too, as this is truly a honey of a listening spot.

The view from our off-grid cabin on PEI.

The first year I took an SDR to the cabin, I made a newbie mistake:  it never dawned on me until I arrived and began to put it to use that my Goal Zero portable battery pack didn’t have a pure sine wave inverter; rather, I found it had a modified sine wave inverter built into it. The inverter could easily power my SDR, sure, but it also injected incredibly strong, unavoidable broadband noise into the mix. It rendered my whole setup absolutely useless. I gave up on the SDR on that trip.

Both the Airspy HF+ (top) and FDM-S2 (bottom) use a USB connection for both data transfer and power. Photo by Guy Atkins.

Today, most SDRs actually derive their power from a computer or laptop through a USB cable, one that doubles as a data and power cable. This effectively eliminates the need for a separate power system and inverter.

Of course, your laptop or tablet will need a means of recharging in the field because the attached SDR will drain its battery a little faster. Nowadays it’s possible to find any number of portable power packs/banks and/or DC battery sources to power laptops or tablets, as long as one is cautious that the system doesn’t inject noise. This still requires a little trial and error, but it’s much easier to remedy than having two separate power sources.

Portable computers

Even a Raspberry Pi 3B has enough horsepower to run SDR applications.

An SDR is nothing without a software application to run it. These applications, of course, require some type of computer.

I the past, SDR applications needed some computing horsepower, not necessarily to run the application itself, but to make spectrum recordings.  In addition, they often required extra on-board storage space to make these recordings sufficiently long to be useful.  This almost always meant lugging a full-sized laptop to the field, or else investing in a very pricey tablet with a hefty amount of internal storage to take along.

Today we’re fortunate to have a number of more portable computing devices to run SDR applications in the field: not just laptops or tablets, but mobile phones and even mini computers, like the eminently affordable $46 Raspberry Pi. While you still have to be conscious of your device’s computing horsepower, many small devices are amply equipped to do the job.

Storage

64-128 GB USB flash/thumb drives are affordable, portable storage options.

If you’re making spectrum and audio recordings in the field, you’ll need to store them somehow. Wideband spectrum recordings can use upwards of 2GB of data per minute or two.

Fortunately, even a 64GB USB flash drive can be purchased for as little as $7-10 US. This makes for quick off-loading of spectrum recordings from a device’s internal memory.

My portable SDR setup

It wasn’t until this year that all of the pieces finally came together for me so that I could enjoy a capable (and affordable!) field-portable SDR setup. Two components, in particular, made my setup a reality overnight; here’s what made the difference.

The AirSpy HF+ Discovery

Last year, AirSpy sent me a sample of their new HF+ Discovery SDR to test and evaluate. To be fully transparent, this was at no cost to me.

I set about putting the HF+ Discovery through its paces. Very soon, I reached a conclusion:  the HF+ Discovery is simply one of the best mediumwave and HF SDRs I’ve ever tested. Certainly, it’s the new benchmark for sub-$500 SDRs.

In fact, I was blown away. The diminutive HF+ Discovery even gives some of my other benchmark SDRs a proper run for their money. Performance is DX-grade and uncompromising, sporting impressive dynamic range and superb sensitivity and selectivity. The noise floor is also incredibly low. And I still can’t wrap my mind around the fact that you can purchase this SDR for just $169 US.

The HF+ Discovery compared in size to a DVD

In terms of portability, it’s in a class of its own. It’s tiny and incredibly lightweight. I evaluate and review SDRs all the time, but I’ve never known one that offers this performance in such a tiny package.

Are there any downsides to the HF+ Discovery? The only one I see––and it’s intentional––is that it has a smaller working bandwidth than many other similar SDRs at 768 kHz (although only recently, Airspy announced a firmware update that will increase bandwidth). Keep in mind, however, that the HF+ series SDRs were designed to prevent overload when in the presence of strong local signals. In fairness, that’s a compromise I’ll happily make.

Indeed, the HF+ Discovery maximum bandwidth isn’t a negative in my estimation unless I’m trying to grab the entire mediumwave band, all at once. For shortwave work, it’s fine because it can typically cover an entire broadcast band, allowing me to make useful spectrum recordings.

The HF+ Discovery is so remarkably tiny, that this little SDR, together with a passive loop antenna, can fit in one small travel pouch. Ideal.

The antennas

My homebrew NCPL antenna

Speaking of antennas, one of the primary reasons I’m evaluating the HF+ Discovery is because it has a very high dynamic range and can take advantage of simple antennas, in the form of passive wideband magnetic loop antennas, to achieve serious DX.

AirSpy president and engineer, Youssef Touil, experimented with several passive loop antenna designs and sizes until he found a few combinations ideally matched with the HF+ Discovery.

My good buddy, Vlado (N3CZ) helped me build such an antenna per Youssef’s specifications. Vlado had a length of Wireman Flexi 4XL that was ideal for this project (thanks, Vlad!). The only tricky part was penetrating the shielding and dielectric core at the bottom of the loop, then tapping into both sides of the center conductor for the balun connections.  Being Vlado, he used several lengths of heat shrink tubing to make a nice, clean, snag-free design. I’ll freely admit that, had I constructed this on my own, it wouldn’t have been nearly as elegant!

Click here for a step-by-step guide to building your own NCPL (Noise-Cancelling Passive Loop Antenna.

Youssef also sent me a (then) prototype Youloop passive loop antenna. It’s incredibly compact, made of high quality SMA-fitted coaxial cables. It can be set up in about 30 seconds and coiled to tuck into a jacket pocket.  The AirSpy-built loop has a lower loss transformer than the one in the homemade loop, which translates into a lower noise figure for the system.

Click here to read my review of the Youloop.

Let’s face it: SDR kit simply doesn’t get more portable than this.

The computer

My Microsoft Surface Go tablet on a hotel bed.

In the past, I used an inexpensive, circa 2013 mini Windows laptop with an internal SSD drive.  Everything worked beautifully, save the fact that it was challenging to power in the field and the internal capacity of the hard drive was so small (16GB less the operating system). In addition, it was a few years old, bought used, so the processor speed was quite slow.

This year, on the way back from the Huntsville Hamfest, I stopped by the Unclaimed Baggage Center in Scottsboro, Alabama. This center has a wide variety of used portable electronics at discount prices. I felt pretty lucky when I discovered a like-new condition Microsoft Surface Go tablet and keyboard with original charger for $190. The catch? The only data port on the tablet is a USB-C. But I grabbed a small USB-C to standard USB 3.0 dongle (for $2!) and took a risk that it would work with the HF+ Discovery.

Fortunately, it did! Score!

While the Surface Go is no powerhouse, it’s fast enough to run any of my SDRs and make spectrum recordings up to 2 MHz in width without stuttering. The only noise it seems to inject into the mix is a little RFI when I touch the trackpad on the attached keyboard.

Power

One of my LiFePo batteries

The HF+ Discovery draws power from the Surface Go tablet via the USB port. With no additional power supply, the Surface Go may only power the HF+ Discovery for perhaps an hour at most. Since I like doing fully off-grid operations and needed to avoid RFI from inverters, I needed a portable power solution.

Fortunately, the Surface Go has a dedicated power port, so I immediately ordered a DC power cable with a standard car lighter plug.

At the Huntsville Hamfest I also purchased a small 12V 4.5 Ah Bioenno LiFePo battery and paired it with a compact Powerpole distribution panel kit I purchased in May at the 2019 Dayton Hamvention.

The LiFePo battery is small, lightweight, and can power the tablet /SDR combo for hours on end. Moreover, I have noticed no extra noise injected when the DC power is applied.

My HF+ Discovery-based portable SDR kit

My portable SDR kit on a hotel balcony.

Now I have this kit, I couldn’t be more pleased with it. When all of the components of my SDR system are assembled, they work harmoniously. The entire ensemble is also incredibly compact:  the loop antennas, SDR, Surface Go tablet, battery, and distribution panel all fit in a very small travel pack, perfect for the grab-and-go DX adventure.

The entire kit: SDR, cables, Youloop antenna, connectors and adapters all fit in my Red Oxx Lil’ Roy pack.

In November, I took the kit to the coast of South Carolina and had a blast doing a little mediumwave DXing from our hotel balcony. We were very fortunate in that I had two excellent spots to hang the homemade loop antenna: on the main balcony, and from the mini balcony off the master bedroom. Both spots yielded excellent results.

What impressed me most was the fact that the SDR# spectrum display and waterfall were absolutely chock-full of signals, and there was very little noise, even in the popular resort area where we were staying. I found that my portable radios struggled with some of the RFI emanating from the hotel, but the HF+ Discovery and passive loop combo did a much better job mitigating noise.

Check out the AM broadcast band on the spectrum display.

But no need to take my word for it.  If you would like to experience it first hand, why not download an actual spectrum recording I made using this setup?

All you’ll need to do is:

  1. Download the 1.7 GB (.wav formatted) spectrum file at this address
  2. Download a copy of SDR# if you don’t already have an SDR application that can read AirSpy spectrum files.
  3. Install SDR#, and run it.
  4. At the top left corner of the SDR# screen, choose “IQ File (.wav)” as the source, then point it to where you downloaded the file.
  5. Press the play button, and experience a little radio time travel!

This particular recording was made on the mediumwave band on November 17, 2019, starting at around 01:55 UTC.

My portable SDR kit capturing spectrum during a hike in Pisgah National Forest.

I’ve also taken this setup to several parks and remote outdoor locations, and truly enjoyed the freedom of taking spectrum recordings back home to dig through the signals.

Conclusion

I finally have a portable SDR system that allows me the flexibility to make spectrum recordings while travelling. The whole setup is compact and can easily be taken in a carry-on bag when flying.

The glory of this is, I can tune through my spectrum recordings in real time and DX when I’m back home, or even on the way back home, in the car, train, or airplane. It’s simply brilliant.

If you don’t already own an SDR, I can highly recommend the AirSpy HF+ Discovery if you’re primarily interested in HF and MW DXing. If you need a wideband SDR, I could also recommend the recently released SDRplay RSPdx, although it’s slightly heavier and larger than the AirSpy.

Thankfully, I am now an SDR enthusiast that can operate in the field, and this radio has had a lot to do with it. I’ll be logging many hours and miles with the AirSpy HF+ Discovery: its incredibly compact footprint, combined with its brilliant performance, is truly a winning combo.

Click here to check out the Airspy HF+ Discovery

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Dan’s initial review of the Belka-DSP portable shortwave radio

Many thanks to SWLing Post contributor, Dan Robinson, who shares the following guest post:


An Initial Review of the Belka-DSP Shortwave Receiver

by Dan Robinson

A few weeks ago, during daily online excursions, I ran across the Belka-DSP receiver.   This is not really a new receiver. Demonstrations have appeared on You Tube going back into 2019.

The Belka has a price of only about $120 U.S. I felt this was a fairly easy purchase, so I went to the website of Alex Buevky (EU1ME).

The receiver has a tuning range of 1.5 – 30 MHz – note that this is a revision from the description on the Belrig site, which still had a range starting at 3.5 mhz as of the time I am writing this.

The Belka is contained in a small heavy duty metal box – the size reminds one of a few boxes of matches put together – 85x50x20 mm with weight of about 100 grams.  Indeed, the diminutive size is quite striking.

 

Viewing videos of the Belka, including several by Fernando Duarte who runs the FENU site, the immediate impression of the receiver is that it has really decent sensitivity and that it is quiet.

While the menu system appears to be a bit confusing, once you start using the receiver you get used to the logic of it.   From the description of the SDR:

“It is possible to adjust the frequency band both from above, from 2.4 to 4.7 kHz, and from below from 50 to 300 Hz.  In telegraph mode, the frequency band is constant, about 300 Hz, and its center is regulated from 500 Hz to 1 kHz.

The settings of the favorite radio stations can be stored in any of 32 memory locations.

The receiver does not have a built-in speaker, but there is a rather powerful VLF bridge that provides sufficient volume when working with an external speaker, speaker or headphones.

The built-in LI-Ion battery lasts for 24 hours of total operating time on the headphones.

In addition to the built-in battery, the receiver can also work from an external DC voltage source of 5 V.”

The Belrig site is English and Russian, which makes ordering easier.  However, be aware that when you hit purchase using a major credit card you may receive a security alert from the card company.   Once I confirmed, the process completed and I received a verification email from Belrig – quite quickly and efficient.

Communications with Alex has been excellent – he is very responsive to suggestions and input.

The SDR arrived in an excellent small heavy cardboard box wrapped with the typical packing tape for the Belarus postal system.  The receiver itself and a telescopic antenna with BNC connector were wrapped in bubble wrap. No paper instructions – those are available directly at the Belrig site [click here to download PDF manual].

The only other item on the Belrig site is a Panoramic Adapter:

“designed for use as part of a radio receiving path of a transceiver/receiver jointly with a personal computer (PC) and SDR software” according to Belrig.  This Pan@SDR “allows you to visually see the RF spectrum in a band up to 200 kHz as well as to receive and decode different modulation types (depending on a software type). . . [and] may be used without a transceiver as SDR-receiver with fixed oscillator (similarly to SoftRock RX), for example, to listen to amateur and broadcasting stations, to decode and to record telegraph stations with CW skimmer, to control signal quality, to calibrate frequency. It may be used as well as a selective millivoltmeter.”

An unboxing video of the Belrig SDR can be seen here:

Initial impressions

My house in Maryland is notorious for high noise levels – located on a corner, we are surrounded by electric wires on four sides.   My attempts to overcome this with my many main premium receivers involve W6LVP, Wellbrook loops and one PAR-FED long wire located outside, with ANC-4 and other noise reduction efforts in my basement radio shack inside.

When I use various portable receivers upstairs in the den of my home, I usually have to keep them well away from incoming Xfinity/Verizon cable TV and Internet lines.

Usually, I am unable to hear much using portables such as SONY SW-55s and Panasonic RF-B65s while sitting on the sofa in the middle of this large family room due to noise from all of these cable lines.

However, interestingly – using the Belka-DSP receiver I was able to get decent reception at this spot.   I attribute this to the metal construction of the receiver, compared to portables with plastic cases.

Certain portables, notably the CountyComm/Tecsun GP5/PL-360-365 are extremely sensitive to being handled, with substantial signal loss once your hand is removed from the cabinet.  The Belka-DSP exhibits sensitivity to touch, but not as much signal loss as there is when you take your hands off a Tecsun PL-365.

I did notice a few frequencies on the Belka where there are digital artifacts – one occurs at or around 11,810 kHz, the BBC frequency.   You can see that in the accompanying video as I tuned up from 11,810.

Others are noticed at various points all the way up through the receiver’s top tuning range of 30 MHz, though thankfully most are not in major SWL bands.

Digital audio artifacts are seen on portable receivers using IC chips, notably the XHDATA D-808 which has several annoying digi-burps on some key frequencies occupied by stations.   On my D-808 for example, 9,650 kHz has a digital artifact that interferes with reception of Guinea.

Tuning on the Belka is simple once you get used to the steps.  The knob on the right serves for tuning, selection of tuning steps, volume, high-low sensitivity, the various audio “cut-off” modes which essentially function as DSP selectivity.   There are 32 memories. Modes are: LSB, USB, CW, NFM, AM1, AM2. For AM mode, AM1 is the most useful, as AM2 seems to be quite harsh in its various DSP audio modes.

The Belka is very sensitive to the type of speaker it is plugged into, assuming you are not using a bluetooth dongle.  Connecting via a 3.5 mm cable to a basic Brookstone speaker that has bluetooth produced audio overloads on the Belka, requiring careful placement of the speaker in proximity to the radio.

Whether this had anything to do with the quality of 3.5 mm cable I was using, I am not sure.  These audio overload issues were not present using the DSP only with a pair of quality SONY studio headphones.  I have not tested the Belka yet with a bluetooth dongle. So be prepared to do some experimenting with speakers and cables.

As mentioned by one person on SWLing Post, the surprise when I received the Belka was that the tuning range is actually 1.5 to 30 MHz rather than 3.5 MHz shown on the Belrig description and in the video there.

This certainly makes the small Belka more attractive, though one wonders why it could not include the full medium wave band.

Also unclear is whether the Belka will have the capability in future for firmware updates, and addition of any new features such as bluetooth though I have to think that adding bluetooth would impact battery duration.

I posed four questions to Alex, including why he made the decision to have the battery soldered in rather than easily user replaceable with battery terminals, whether he is considering adding bluetooth capability, adding capability for firmware updates, and whether he is thinking about extending coverage to include the full medium wave band.

Alex thanked me for my “interesting questions” adding:

“Now  Belka-DSP  is a final  product in this  regard no updates or modifications are planned in the near future.  We do think about the way how to improve this receiver, how to make it even  more user friendly, but I can not say exactly which changes will take place and when.  Looking forward for your future questions.”

Alex says that the Belka receivers ship out with batteries not fully charged to comply with post office regulations.

For me, the battery issue is a bit annoying.  Similar to cellphones with built-in batteries this means that when the Li-Ion cell does deteriorate you are stuck with a bit of soldering to replace it – and I am not good at soldering.

Another example of this practice is the Pocket SDR made by Gerhard Reuter in Germany which uses flat Li-Ion batteries that are soldered in.  If you have no problem using soldering irons, then none of this is a concern.

I can live without on-board Bluetooth, since dongles are available online.  But I would like to see coverage of the full medium wave band and it would certainly be nice to have FM band coverage.   Obviously the ability to update the radio’s firmware would be a welcome addition.

Another suggestion I would make to Alex would be to provide some way to quickly move from band to band, similar to the capability seen on most regular portables.  Having to constantly press the side knob to switch to rapid 50 kHz slewing to move say, from 49 meters to 19 meters, involves too much fiddling.

It would be interesting to see the internals of the Belka radio – four Philips screws are located on the left and right sides of the receiver, so that should not be difficult, though I have chosen not to go exploring inside mine.

Summary

Overall, I am very impressed with the Belka.  This seems to be an amazingly quiet and sensitive little receiver.  It’s obviously similar to the CR-1a in that it has a display, but much smaller and perfect for Dxing on the road, with a BNC connector that enables connection of any amplified antenna, loops or longwires.

I have included a video made outside my house using only the BNC telescopic antenna with the Belka, showing reception at about 1800 to 1830 UTC of some major stations in the SW bands.

This demonstration shows how sensitive the Belka is in broad daylight hours (also shown is my SONY SW-1000T).

A search of YouTube shows at least two other handheld DSP receivers being demonstrated in 2019, both with full scope screens, seemingly experimental units and on Russian YouTube channels.  There is some discussion of availability, but as of early 2020 these units do not seem to be available.

It’s unclear whether any of these units ever made it to production on any scale.  Comparing the features on these to the Belka – including AGC, Noise Reduction, Squelch, etc – it seems there might be quite a bit of space on the open market for SDRs that far exceed the capabilities of the Belka.

On the other hand, inclusion of larger scope displays would clearly have implications for battery life, which is one area where the Belka SDR – with its claimed 24 hour duration – obviously excels.

I will be interested to read other user reviews of the Belka-DSP – for now, it appears to be the only receiver of its kind and size being produced in significant numbers, so I certainly want to thank Alex for bringing it to the market.


Thanks so much, Dan for sharing your review of the Belka-DSP. I agree that likely the reason the Belka-DSP is less prone to the effects of holding and grounding is because it has a metal case and is probably better shielded. I agree that there should be an easy way to move between the various meter bands. Including features like this is always a concern in terms of ergonomics for small radios with simplified controls.

It is a fascinating and unique little receiver. Since it’s designed and produced by a “mom and pop” company, I imagine upgrades won’t happen unless there’s a new version produced at some point. With that said, this engineer obviously has the know-how to make a capable receiver! 

Thanks again, Dan, and we look forward to any/all updates you wish to share!

Click here to check out the BelkaDSP product page.


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Mike reviews the Retekess TR608 AM/FM/AIR/SW receiver

Many thanks to SWLing Post contributor, Mike S, who shares his assessment of the Retekess TR608. Mike writes:

For this model, the company marketing electronics under the Retekess brand seems to be using a different supplier compared to the previous digital-radio-plus-memory—card-player products. The result is a more traditionally styled multiband DSP radio which runs on (gasp) traditional AA batteries. Its feature set takes inspiration from the Radiwow R108 and original CCrane Skywave, but with mixed results (albeit at a fraction of the price). It delivers decent performance for its price class but more serious listeners would be advised to spend a little more on a more established model.

Pros

    • Usual set of features: sleep timer, alarm, scanning, auto memory fill.
    • Uses replaceable alkaline or NiMH “AA” cells.
    • Decent sensitivity across the board.
    • Full shortwave coverage.
    • Frequency display is large and contrasty.
    • Dial light is effective and can be disabled. Display is readable without it, even in dim light.
    • No annoying keypad “beep”, so no mad rush to discover how it can be disabled.
    • Speaker can play reasonably loud without distortion.
    • FM reception is solid with good frequency response and stereo reception through headphones; this also activates a display indicator.
    • MW/SW reception is NOT plagued by digital hash bleeding through from the processor as with most other models in this price range!

Cons

    • Significantly larger than expected.
    • Unfortunately the added cabinet space is not utilized for a more wide-range speaker; audio is tinny.
    • Clumsy mounting of one spring in the battery compartment on my sample makes it almost impossible to insert the third AA battery without risking damage.
    • Many keypad buttons are so tiny and almost flush with the cabinet, that they are difficult to press.
    • Lens over LCD display is molded and unpolished with moiré distortion at some viewing angles.
    • Air band reception marred by birdies, bleed-through from other bands, and lack of squelch.
    • Volume control defaults back to level “10” under some circumstances (the manual warns about this).
    • Confusing 2-level LOCK function requires close attention to almost microscopic indicator on LCD.
    • No battery level indicator.
    • Although the manual advises that batteries can be charged using the 4.5V coaxial socket, no charging indicator is obvious.
    • Rotary knob, used for both tuning and volume adjustments, has no detents and so can easily spin off target.
    • Assigned function (no indication) depends on whether the tuning or volume buttons on the keypad were the last to be used.
    • No fine tuning outside of pre-programmed increments.
    • MW selectivity is a bit too wide for congested night reception.
    • MW reception occasionally exhibits weird artifacts; ghost images, sputtering audio on marginal signals, and “processed” sounding voice audio. Don’t know if these are DSP or AGC related, or a mixture of both. I have observed the same thing with the Eton Mini and other inexpensive portables using marginal DSP implementations.

SHOWSTOPPER ALERT: MW band channel assignments marred by 9kHz-centric firmware bug. Even after changing to 10kHz channel spacing (undocumented), the CPU still “thinks” in 9kHz assignments for direct input. Entering FREQ-1-0-1-0-FREQ should get you to 1010 kHz; but it actually lands on 1018 kHz because that is the nearest channel in the 9kHz band plan. You are now stuck in frequency step hell, as the up-down frequency keys still operate in 10KHz mode but do not know they are now off bandplan. UP/DOWN yield 1028/1008, not 1020/1000. The only way to recover is to enter a MW frequency that is the same in both bandplans, or to power off and double-reset the step rate resulting in all memories being lost.

Thank you so much for the review, Mike.  It sounds like this little receiver isn’t ready for prime time yet. The issues with frequency steps on the mediumwave band is certainly a show-stopper for anyone in North America. Indeed, it sounds like mediumwave reception, in general, is mediocre at best. At least the receiver isn’t plagued with internal noises.

With pricing around $29.99-$39.99 it’s certainly a bargain radio. But I’m sure you’re thinking what I’m thinking: you pay for what you get.

The Retekess TR608 can be purchased on eBay or Amazon.com (affiliate link).

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Mike compares the SDRplay RSPdx on mediumwave and longwave

Many thanks to SWLing Post contributor, Mike Ladd with SDRplay, who shares the following videos comparing the new RSPdx with a number of benchmark SDRs:

SDRplay RSPdx and ELAD FDM-S2 weak NDB station

SDRplay RSPdx and ELAD FDM-S2 medium wave selectivity

SDRplay RSPdx and Airspy HF+ Discovery medium wave selectivity

SDRplay RSPdx and Airspy HF+ Discovery weak NDB station

SDRplay RSPdx and Microtelecom Perseus medium wave selectivity

SDRplay RSPdx and Microtelecom Perseus weak NDB station

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