Category Archives: Reviews

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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The Sony ICF-7600A continues to impress

I mentioned in a previous post that SWLing Post contributor, Ed Earps, recently gifted me his Sony ICF-7600A.

I’ve been having a field day with this radio!

Well, many field days, in fact. Early on, I packed the ‘7600A in my Red Oxx Hound EDC pack–it fits in the Hound’s interior pocket perfectly and is well-protected on all sides. The radio has pretty much lived in my car and truck since then, thus has gotten a lot of air time when I take short breaks throughout the day.

In November, I took the ‘7600A to Mount Mitchell (6,684 feet/2,037 meters above sea level) and to coastal South Carolina (sea level). It’s been a great radio companion and has given me an excuse to go “old school” and do a little analog band-scanning.

The ICF-7600A certainly has some strengths.

For one thing, although I’ve let this radio on for extended listening sessions, I’ve yet to deplete the eneloop rechargeable batteries (Amazon affiliate link) I originally installed in October. Obviously, this radio will run for days on batteries–a serious plus if DXing off-grid.

The ‘7600A is a fantastic portable for mediumwave DXing. Although it’s also a very sensitive and selective shortwave receiver–especially in this class and era of analog portable–I think mediumwave may be its strong suit.

On the negative side, some of the shortwave band selections are truncated and for some reason, it doesn’t have a back stand (quite an odd omission). Still, these are pretty minor cons.

Obviously, the pros outweigh the cons on this brilliant vintage portable that seems to have held up very well over the years.

To ensure its longevity–and as a precaution–I do think I’ll take it to Dr. Vlado to have all of the caps replaced soon.

My thoughts? If you ever stumble across an ICF-7600A at a hamfest or on eBay, I say grab it!

Post readers: Anyone else love the ICF-7600A? Did I miss any major pros or cons? Please comment!


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Ivan tests the SDRplay RSPdx’s HDR mode

Many thanks to SWLing Post contributor, Ivan (NO2CW), who writes:

The new RSPdx has what they call “High Dynamic Range: (HDR) mode below 2 mHz. I tested a day after receiving the new unit by turning HDR mode on and off. It seemed to make quite a difference when receiving Non Directional Beacons.

As far as Medium Wave itself, I did see some difference but it was harder to make conclusions there as propagation of weak signals on medium wave can change up and down in the course of a minute and some additional testing on Medium Wave will be done in the future. Overall for anyone interested in the world below 2 mHz HDR mode is definitely something to explore!

My video is here:

Thank you for sharing, Ivan!

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A review of the SDRplay RSPdx wideband SDR receiver

SDRplay recently announced the latest product in their line of affordable 14 bit wideband SDRs: the SDRplay RSPdx.

For over two weeks now, I’ve had an early production model of the RSPdx here in the shack operating on a beta version of the SDRuno application.

In the spirit of full disclosure, SDRplay is a long-time supporter of the SWLing Post and I have alpha- and beta-tested a number of their products in the past. This early production RSPdx was sent to me at no cost for a frank evaluation, and that’s exactly what I’ll offer here. To be clear, while I am using beta software, this is not a beta SDR, but one from a first limited production run.

And thus far, I must say, I’m impressed with the RSPdx. 

Upgrades

The RSPdx has been introduced as a replacement for the RSP2 and the RSP2pro receivers. It has been updated and upgraded, with a completely new front-end design.

Here are the highlighted improvements and changes:

  • Performance below 30 MHz has been enhanced when compared to the RSP2/RSP2pro.
  • Performance below 2 MHz has been substantially upgraded. Through the use of the new HDR mode, both dynamic range and selectivity have been considerably improved.
  • There is now a BNC antenna connector on antenna C position instead of a HiZ port. Both A and B antenna ports are SMA like other RSP models.

Let’s face it:  those of us interested in low-cost SDRs are spoiled for choice these days. The market is chock-full of sub-$200 SDRs, especially if you include all of the various RTL-SDR-based SDRs and knock-off brands/models one can find on eBay.

Personally, I invest in companies that support radio enthusiasts for the long haul…those that do their own designs, innovations, and production. SDRplay is one of those companies.

SDRplay’s market niche has been providing customers with affordable, high-performance wideband receivers that cover an impressive 1 kHz to 2 GHz.

Wideband coverage can come at a cost. Unless you pay big money for a commercial-grade wideband receiver, you’re going to find there’s a performance compromise somewhere across the spectrum.  On the RSP2 series, those compromises would have been most apparent on frequencies below 30 MHz.

That’s not to say HF, MW, and LW performance was poor on the RSP2 series–indeed, it was quite impressive and well-balanced; it just didn’t stack up to the likes of the similarly-priced AirSpy HF+ and HF+ Discovery, in my humble opinion. Both little Airspy SDRs have wooed DXers with their impressive dynamic range and overall ability to work weak signals in the HF portion of the spectrum.

Neither of the AirSpy HF+ models are wideband receivers, but still offer a generous range:  9 kHz to 31 MHz and from 60 to 260 MHz––about 11.5% of the frequency coverage of RSP models. (Note that the Airspy R2 and Mini do cover 24 – 1700 MHz.) For shortwave radio listeners that also want to venture into the UHF and SHF regions, a wideband SDR is still required.

It’s obvious SDRplay’s goal is to make the wideband RSPdx into a choice receiver for HF and, especially, for MW/LW DXers. But have they succeeded? Let’s dive in…

Performance

As I say in most of my SDR reviews: doing comparisons with receivers that have so many features and adjustments is never easy. In other words, we want an apples-to-apples comparison, but it can be difficult to achieve, especially with new products.

I compared the SDRplay RSPdx with the WinRadio Excalibur and Airspy HF+ Discovery. Here’s how I set up my comparisons:

The RSPdx, Excalibur, and HF+ Discovery all used the same antenna in my tests––a large, horizontal delta loop antenna, via my ELAD ASA15 amplified antenna splitter. I’ve used this antenna splitter for years and can vouch for its equitable, lab-grade distribution of signal.

The RSPdx is not in full production at time of posting, thus application options are limited. Typically, I’d load comparison SDRs in SDR Console or HDSDR and test them with identical settings as well. At present, the RSPdx is only compatible with a beta version of SDRplay’s own application, SDRuno (which will come out of beta rior to the first major production run). The benefit of using SDRuno is that you unlock the full potential of the RSPdx, plus signal and noise numbers are incredibly accurate.

For each SDR in this comparison, I used their native/OEM application to give them the best possible performance.

I also matched filter settings and made an effort to match AGC and volume settings as closely as I could.

Additionally, I resisted the temptation of comparing my RSP2 with the new RSPdx because I didn’t want to run two simultaneous instances of SDRuno on the same computer––especially considering one was in beta.

Is this comparison perfect?  Probably not, but I did the best with the time I had available. I do intend to make further comparisons in the future.

Longwave performance

Via the RSPdx’s new “HDR” mode, both dynamic range and selectivity have been considerably improved with frequencies below 2 MHz. While I’ll fully admit that I’m not much of a longwave DXer, my very first listening session with the RSPdx started in this region of the spectrum.

In fact, the first evening I put the RSPdx on the air and confirmed that I was, indeed, in HDR mode, I noticed a small carrier via the spectrum display on 171 kHz. I clicked on it and quickly discovered it was Medi 1. The signal was faint, but I could clearly ID at least one song. This truly impressed me because I believe this was the first time I had logged Medi 1 on longwave from the shack.

I didn’t connect the Excalibur at that point to see if it could also receive the faint Medi 1 signal, but I imagine it could have. I’m pretty sure this would have been outside the reach of the RSP2, however.

I tried to explore more of the longwave band, but due to local RFI (I suspect an appliance in my home), most of the LW band was inundated with noise. With that said, I did grab three of my benchmark non-directional beacons.

Obviously, the RSPdx is a capable LW receiver.  I would like to spend more time on this band once I’ve tracked down the source of my local RFI.

Mediumwave/AM performance

In the past two weeks, I’ve spent many hours with the RSPdx on mediumwave.

We’re heading into the winter months in the northern hemisphere, and that’s normally when my listening habits head south on the bands.

In short: I find the RSPdx to be quite sensitive and selective on the mediumwave bands while the HDR mode is engaged. A major improvement over its predecessor.

I primarily compared the RSPdx with my WinRadio Excalibur on mediumwave since I consider the Excalibur to be a benchmark MW receiver. And, as you’ll hear in the screencasts below, the RSPdx truly gives the Excalibur a run for its money:

740 AM – RSPdx vs. Excalibur:

860 AM – RSPdx vs. Excalibur:

Note that my horizontal delta loop antenna is omni-directional, hence the tug-of-war you hear between stations in the clips above.

In truth, I could have done more to stabilize the signal on both of these fine SDRs, but I wanted to keep the comparison as fair as possible.

You might have noticed that both were running AM sync mode. It seems the sync lock on the RSPdx may have also improved––though I would need to do a direct comparison with the RSP2 to know for sure––but in terms of stability, I still found that the WinRadio Excalibur was superior. Mind you, the Excalibur is a $900 – $1,000 receiver and has the strongest synchronous detector of any radio I’ve ever owned.

Shortwave/HF

SDRplay notes on the preliminary specifications sheet that the RSPdx has been “enhanced” when compared with the RSP2 series.

And, after having spent two weeks with the RSPdx on the shortwave bands, I would say this is a bit of an understatement. For although I haven’t compared the RSPdx directly with the RSP2 yet, I do feel HF performance is substantially better than its predecessor. Indeed, in my comparisons, I often found it gave the Excalibur some serious competition. Overall, the Excalibur had an edge on the RSPdx, but the gap has closed substantially. That’s saying something.

For the comparison videos below, I also included the excellent AirSpy HF+ Discovery.

40M LSB – RSPdx vs. HF+ Discovery:

80M USB – RSPdx vs. Excalibur:

31M Broadcast – RSPdx vs. HF+ Discovery:

As you can see and hear, the RSPdx is now in the league of some of the finest HF receivers in my arsenal.

But I’m curious to know what you think after listening to these comparisons. Please comment!

Notch Filters

For those of you living in areas with DAB/DAB+ broadcasters nearby, you’ll be happy to note that the RSPdx has a DAB filter to help mitigate any potential overloading.

Also, if you live near a blowtorch mediumwave station, you’ll be quite pleased with the MW notch filter. It’s so effective at filtering out the mediumwave band, my local blowtorch on 1010 kHz is barely visible on the spectrum once the notch filter is engaged. (Note: I should add that neither the DAB nor the mediumwave notch filter was engaged during any of my previous comparisons above.) Check out the screen shots below showing the mediumwave band before and after the MW notch filter is engaged:

Before:

After:

Summary

For those of you looking for a budget wideband SDR with solid performance below 30MHz, look no further.

For $199 US, you’re getting a quality UK-designed and manufactured SDR in a proper metal housing.  The OEM application, SDRuno, is one of my favorite SDR applications and can fully take advantage of the RSPdx’s new HDR mode. No doubt, with a little more time, most third-party SDR applications will also support the RSPdx.

Frankly, I was expecting classy mediumwave and longwave performance as this was the most touted upgrade of the RSPdx. SDRplay certainly delivered.

In my experience, SDRplay doesn’t oversell their products. Their preliminary product sheet mentioned improved performance on HF, but their press release didn’t even mention the HF upgrades. And this is where I, in particular, noticed significant improvement. Perhaps this is because I am primarily an SWLer, thus spend a larger portion of my time in the HF region.

SDRplay products also have a mature, robust SDR application via SDRuno. Day to day, I tend to use Simon Brown’s SDR Console as my primary SDR application, since it’s compatible with so many of my SDRs and also offers some of the best recording functionality for those of us who do audio and spectrum archiving. Each time I beta test or review an SDRplay SDR, however, I’m more and more impressed with SDRuno. It’s evolved from being a rather cluttered application to one with a thoughtful, cohesive user interface that’s a joy to use––a product of true iterative agility.

Indeed, after having used SDRuno exclusively these past two weeks, I believe I would consider it as my primary SDR application…if only it had audio recording in addition to spectrum recording, and could run multiple instances with multiple SDRs. Again, given a little time, I wouldn’t be surprised if some of this functionality is eventually integrated.

Questions?

Since many SWLing Post readers already own an SDR, I’m sure some of you will have questions. Let’s address a few of those right now.

Question: “I have an RSP2/RSP2pro. Should I upgrade to the RSPdx?”

My recommendation: If you are a shortwave, mediumwave, or longwave DXer, I would indeed recommend upgrading to the RSPdx. If you primarily use your RSP2 series SDR on frequencies above 30 MHz and only occasionally venture below for casual listening, then I’d keep the RSP2.

Question: “I have an RSP1a. Should I upgrade to the RSPdx?”

My recommendation: If you’ve been enjoying your RSP1a and would like to take your listening/monitoring to the next level, then, yes, I would upgrade. Not only can you take advantage of the RSPdx’s enhanced performance, but the RSPdx affords you three antenna ports, and has a more robust front end.

Question: “I have an RSPduo. Should I buy the RSPdx?”

My recommendation: I’m a big fan of the RSPduo. Unless you’re a dedicated mediumwave/longwave DXer, or you’d just like to add another separate SDR to your radio arsenal, I wouldn’t rush out to buy the RSPdx.

And while I’m offering advice, I’d like to offer my standard two cents on the subject of performance optimization: a radio is only as good as its antenna! If you have a compromised antenna, invest in your antenna before upgrading your radio. You’ll be glad you did.

Conclusion

Happily, I can  recommend the SDRplay RSPdx without hesitation. This latest iteration of the RSP series SDR is a proper step forward in terms of performance and functionality––obviously implementing years of customer feedback.

SDRplay also has a proven track record of innovation and customer support. Their documentation, video tutorials, and community are among the best in the industry. Purchase with confidence.

Click here to check out the RSPdx at SDRplay.


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It’s not a travel radio if it doesn’t have an alarm clock

The CC Skywave SSB is set to wake me at 3:30 to catch a 5:30 flight.

I have a pretty accurate body clock. Regardless of when I doze off, I always wake up at the same time.

When I’m at home on my regular schedule, I trust my “internal chronometer” so much, I haven’t set an alarm in years.

When I travel, it’s a completely different story…

It’s a rare occurrence when a flight, train, or even road trip allow me to wake up at my normal time, so I rely on an alarm clock.

In fact, I’ll let you in on a little secret: I’m a nervous Nellie when I’m forced to break my sleep cycle to catch an early flight. My fear of missing a flight may even border on paranoia–I’ll wake up multiple times during the night in a panic unless I feel completely at ease that there’s an alarm system in place to wake me no matter what.

I recently told a friend about this fear and he asked, “Why not just set the alarm on your phone?!”

Simple answer: I don’t trust smart phones and tablets. They’re too complicated with so many nighttime settings, alarm/alert volume levels, short battery life, etc. etc.

Case in point…

Earlier this year, I had to catch an early flight and needed to wake up at 4:00 AM, so I scheduled my iPhone and iPad to alarm at 4:00. (When at home, I try to have my iPhone/iPad wake me first, because the alarm is very gradual and doesn’t disturb my wife.) Of course, I also set my travel radio’s alarm clock for 4:10, as a fail safe.

Knowing I had a total of three(!!!) alarm clocks set, I slept like a baby.

At 4:10 AM, my travel radio alarm started beeping. The iPhone and iPad were completely silent.

Turns out, the iPad decided to do an operating system update during the night. For some reason, after rebooting, it simply forgot about the alarm. (Thanks, iPad!) And the iPhone? I’m still not sure how/why, but the mute switch on the side of the phone was engaged and if it vibrated to wake me, I never heard it rumbling on the night stand.

Thank goodness the travel radio had my back, else I would have missed that flight.

Travel radios: Never leave home without one!

I like to be a self-sufficient traveler even though I only travel with one bag and pack very lightly. I never rely on my destination to have a functioning alarm clock (with battery backup, of course) or effective wake up call service. Regardless of how minimally I pack, I always take a travel radio.

In February, for example, I travelled to Philadelphia for the Winter SWL Fest. Even though my trip was nearly a week long, to keep from paying a carry-on fee with Frontier airlines, I packed everything in a bag that met their strict “personal carry-on” bag size.

Regular readers know I’m a bit of a pack geek, so my bag of choice was the Tom Bihn Stowaway.  Here’s the bag fully packed out at my feet in the airport:

Here’s a photo of everything I packed in the Stowaway for that trip:

This particular trip really pushed the limits on my minimalist travel philosophy. Honestly? It was a fun challenge! I had to hone my pack contents down to only the essentials (don’t make fun of me for believing three flashlights were essential–the previous year, our hotel was without power for several days).

Still, I made room for one of the smallest travel radios in my arsenal: the County Comm Marathon ETFR:

I chose the ETFR because it has a custom case that could attach to my belt or pack strap if interior space became too tight. The ETFR radio hasn’t been in production for a decade, but it’s an effective radio companion and the alarm works without fail.

Choosing a travel radio

Most modern digital portables are based on DSP chips that have clock and alarm functions, so you might already own an effective travel radio.

With that said, I always prioritize radio features that benefit a traveler, of course; here are some that I look for:

  • Small size: Naturally, it’s sensible to look for a travel radio that’s small for its receiver class for ease in packing.
  • Overall sturdy chassis: Any travel radio should have a sturdy body case that can withstand the rigors of travel.
  • Built-in Alarm/Sleep Timer functions: We’ve already exhausted this topic, right?.
  • Powered by AA batteries: While the newer lithium ion battery packs are fairly efficient, I still prefer the AA battery standard, which allows me to obtain batteries as needed in most settings; a fresh set of alkaline (or freshly-charged) batteries will power most portables for hours on end.
  • Standard USB charging cable: If I can charge batteries internally, a USB charging cable can simply plug into my smart phone’s USB power adapter or the USB port on my laptop; no extra “wall wart” equals less weight and less annoyance.
  • ETM: Many new digital portables have an ETM function which allow auto-scanning of a radio band (AM/FM/SW), saving what it finds in temporary memory locations–a great way to get a quick overview of stations.  (As this function typically takes several minutes to complete on shortwave, I usually set it before unpacking or taking a shower. When I return to my radio, it’s ready to browse.)
  • Single-Side Band: While I rarely listen to SSB broadcasts when traveling, I still like to pack an SSB-capable receiver–especially for longer trips.
  • RDS: Though an RDS (Radio Data System) is FM-only, it’s a great feature for identifying station call signs and genre (i.e., public radio, rock, pop, country, jazz, classical, etc.)
  • External antenna jack: I like to carry a reel-type or clip-on wire external antenna if I plan to spend serious time SWLing. Having a built-in external jack means that the connection is easy, no need to bother with wire and an alligator clip to the telescoping whip.
  • Tuning wheel/knob: Since I spend a lot of time band-scanning while travelling, I prefer a tactile wheel or knob for tuning my travel radio.
  • Key lock: Most radios have a key lock to prevent accidentally turning a radio on in transit–but with a travel radio, it’s especially important to have a key lock that can’t be accidentally disengaged.
  • LED flashlight: Very few radios have this, but it’s handy to have when travelling. Note that the County Comm ETFR (above) does!
  • Temperature display: Many DSP-based radios have a built-in thermometer and temperature display; I like this when I travel anytime, but especially when I’m camping.

While I don’t have a portable that meets 100% of the above travel radio wish-list, I do have several that score very highly.

Since this is a favorite topic, I’ve written a number of articles with reviews of travel radios. In my CC Skywave SSB review last year, I list a number of current favorites.

I should also mention that one great deal at time of posting is the Eton Executive Traveler.

It’s a brilliant little radio for $34.99 shipped (note this affiliate link supports the SWLing Post).

One of our readers has been following the price of this little radio for months–it’s being sold at an all-time low at present.

What’s in your travel pack?

What’s your favorite travel radio? What features are important to you? Anyone else paranoid about missing early flights? 

Please comment!


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Final review of the CommRadio CTX-10 QRP general coverage transceiver

Earlier this year I published what I called an “initial” review of the CommRadio CTX-10 QRP transceiver, promising an eventual final review. The reason for this is that I sensed there were important CTX-10 updates on the horizon, and I wanted to re-evaluate the rig once the upgrades had been implemented through firmware.

This final review builds upon the initial review––think of it as the  second installment, or “Part 2″––so if you’re considering the purchase of a CTX-10 and haven’t read the previous post about it, please do read the initial review first.

Upgrades

As anticipated, via simple at-home firmware updates, since my initial review the CTX-10 has now been upgraded and tweaked a number of times. [Click here to view all of the documented firmware updates and notes at CommRadio.]

I’ve been very pleased with the attention CommRadio has paid to their customer feedback on some of the most important requests.

Instead of reiterating what I wrote in the initial review, I’ll jump straight into the upgrades.

Operating split

At time of posting my initial review, the CTX-10 didn’t have A/B VFOs. This was my primary gripe about the CTX-10, because without A/B VFOs, there was no way to operate split, which meant that you could not work DX stations that use split to manage large pileups. This is actually a really important feature for a QRP radio because during split operation, a pileup is pulled apart across a few kHz of bandwidth, thus giving a 10-watt signal a better chance of being heard through a collection of legal-limit signals.

On June 10, 2019, CommRadio released a firmware package that added A/B VFOs and the ability to operate split to the CTX-10.

Even though there are only a limited number of buttons on the front panel, it’s incredibly simple to enter into split mode:

  1. Chose the frequency and mode;
  2. Hold the STEP button for one second or more, then release. You’ll then see a split display indicating the TX and RX frequencies.
  3. Use the left arrow key [<] to toggle between them.

I do like the clear TX and RX lines, which leave no doubt in the user’s mind what the frequency used for transmitting and receiving is. On some radios, this can be a bit confusing.

Split operation is simple and effective, thus I consider this issue fully resolved.

ATU flexibility

In my initial review, I noted that the CTX-10 ATU needed near-resonant antennas for the ATU to make a strong 1:1 match. Indeed, a number of times I actually used a near-resonant antenna in the field––the EFT Trail-Friendly, for example––and the ATU couldn’t get below a 3:1 match. For what it’s worth, CommRadio states that the CTX-10 can easily handle 3:1.

Making a Parks On The Air activation at Tar Hollow in Ohio.

CommRadio has made modifications to the ATU function, improving the performance of the antenna-tuner algorithm, which had a significant impact on 80 and 60 meters. I’ve also had better luck with a number of field antennas I’ve tried on 40 and 20 meters. Is it as good as the Elecraft KX-series ATUs? No, but I consider those ATUs to be some of the most flexible on the market.

Having a built-in ATU on the CTX-10 is certainly a valuable feature in the field. When I need to match a challenging antenna with the CTX-10, I bring my Emtech ZM-2 manual tuner along for the ride. A perfect combo.

SSB operation?

There still is no way to adjust the microphone gain control nor microphone compression on the CTX-10. Much like a military or commercial radio, the CTX-10 is optimized for just one style of mic: in its case, the modular MFJ-290MY or Yaesu MH-31A8J handheld mic.

The CTX-10 microphone input has a limiting pre-amplifier with built-in compressor and ambient noise gate–in short, the CTX-10 handles all microphone settings automatically.

Through firmware updates, a number of positive adjustments have been made to the microphone settings:

  • the microphone-decay timer has been tweaked so that audio clipping is less of a concern
  • audio clarity and gain have been improved
  • audio power has been improved resulting in .5 to .75 watts of additional peak power
  • microphone audio leveling has been improved
  • VOX attack and decay timing has been improved

These are all welcome adjustments.

I would note here, though, that if you plan to use a mic other than the MFJ-290MY or Yaesu MH-31A8J handheld mics, you will have a limited means of adjusting the mic parameters unless you have an external mic EQ. A number of readers, for example, have asked about using their Heil boom headset with the AD-1-YM cable adapter on the CTX-10. Boom headsets are a wonderful tool for field operation because they free your hands to log contacts. As for using boom headsets on the CTX-10, since I don’t have the appropriate adapter, I can’t speak to this. But since you can’t control mic gain, it might take time to learn how to position the boom mic and adjust your voice level for optimum performance.

CW operation

As mentioned in our initial review, the CTX-10 does not support QSK/full break-in operation. Rather, the CTX-10 uses a traditional relay for switching between transmit and receive.  During CW operations, you’ll hear a faint relay click when switching from TX to RX and back again.

This isn’t a problem for me, as I rarely set my CW rigs for full break-in, but the CW hang time delay on the CTX-10 is not currently adjustable. For high-speed CW ops that prefer a faster relay recovery, I suspect this could be an annoyance.

There have been recent CTX-10 firmware upgrades that have helped solve issues found with CW keyer timing in early units. I found the timing issues were mainly present while sending high-speed CW (25 WPM+). My buddy Vlado (N3CZ) put the CTX-10 through some high speed tests, and was pleased with the results overall.

I will reiterate here that the CTX-10 lacks other controls many CW operators appreciate. Currently, the CTX-10 lacks a sidetone control; as a result, you cannot change the sidetone volume/tone, nor can you turn it off. I continue to hope that CommRadio will fix this quirk via a future firmware upgrade.

The CTX-10’s built-in CW keyer does not currently support iambic keying. Meaning, when both levers of a dual paddle are closed simultaneously (squeezed), it will not send a series of alternating dots and dashes. I imagine this could be addressed in a future firmware update.

Additionally, without re-wiring your paddle, you can’t change which side of your paddle sends ‘dits’ and which sends ‘dahs.’  A minor con, for sure–still, most modern QRP transceivers allow you this flexibility.

All in all, the CTX-10 will serve the CW operator much like a military set in field operations. True, I wish it had a few more adjustments, but it has all of the basics, and I’ve received several great reports regarding signal and tone.

Revisiting the basic feature set

Let’s be clear: as I stated at length in my initial review, the CommRadio CTX-10 was designed around simple operation, like one might expect from a military or commercial channelized radio. I know ham radio operators and preparedness enthusiasts who prefer this approach to gear design, and they will appreciate this CTX-10 design philosophy.

Still, the CTX-10 lacks many of the features and adjustments you’d typically find on a QRP transceiver in its price class. Instead, the CTX-10 was designed to handle many of these adjustments automatically.

The CTX-10 still has no separate RF gain control. The CTX-10’s RF gain is directly tied to the three AGC settings (slow, medium, and fast). While I believe it does a fine job of adjusting RF gain, I do ride an RF gain control a lot during noisy summer conditions, and miss this feature.

The CTX-10 still has no passband (PBT) control, notch filter, or noise blanker––all features I’d normally expect in a QRP radio at this price level.

There are no CW (os SSB) memory keyers. I wouldn’t expect these, as I believe only the Elecraft KX2 and KX3 sport this feature in this price class of QRP radios.

Please note: some of these features could potentially be added in future firmware upgrades. If one of these items is keeping you from purchasing the CTX-10, please contact CommRadio and inquire.

Is the CTX-10 for you?

The CTX-10 on air at the W4DXCC conference

With the most recent upgrades, CommRadio has solved the major issues that kept me from heartily recommending it in my initial review.

The addition of split operation was especially key for me, as I do operate split. The more nuanced adjustments to the CW keyer, an extra feature to prevent the radio from accidentally turning on while in transit, and the adjustments to the mic algorithm, all make this radio more pleasant to operate at home or (especially) in the field.

As I mentioned in the initial review, the CTX-10 owner is one who values a very simple, straightforward radio. Perhaps someone who began operating in a commercial, military, or aviation field, and/or who likes the “get on and get the job done” approach.  Someone more interested in making contacts than in radio operations and refinements. Those who want a sturdy, lasting, no-frills, set-it-and-forget-it rig. If that’s you, take a closer look at the CTX-10: it may just suit your needs to a T.

If, however, you’re looking for a full-featured QRP radio with many of the features and nuanced adjustments you’d expect in the shack, check out the Yaesu FT-818, Elecraft KX2, or Elecraft KX3. All of these excellent rigs are time-tested and very flexible.

The two major advantages of the CTX-10 over competitors are:

  • the ability to charge the internal batteries from almost any voltage source, and
  • a higher TX duty cycle (without needing to add external heat sinks).

I believe the CTX-10 will have strong appeal for radio enthusiasts who value these characteristics:

  • All-in-one-box portability with no extra wired accessory components
  • Best-in-class internal battery life
  • Best-in-class intelligent battery charging
  • HF packs
  • Digital modes like FT-8 and the ability to operate them in the field from internal batteries for extended periods of time
  • The equivalent of a simple portable military/commercial set
  • A well-balanced receiver with few manual adjustments
  • Broadcast listening, as the CTX-10 is also superb broadcast receiver
  • Best-in-class hardware

The CTX-10’s overall construction and components are, as I’ve said, near mil-spec. While the CTX-10 isn’t weatherized or waterproof––no more than any of its current competitors––the construction is top-shelf, for sure. It should run for decades without need of repair.

The CTX-10 is built like a tank, and has excellent receiver characteristics for field operation. It’s also designed and manufactured right here in the USA. All the better.

Click here to check out the CTX-10 at CommRadio.

Click here to check price and availability at Universal Radio.


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