Category Archives: Shortwave Radio Reviews

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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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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Dave updates and expands AOR AR-DV1 review

Many thanks to SWLing Post contributor, Dave Zantow (N9EWO), who writes:

A greatly updated and expanded review on the AOR AR-DV1 has now been posted by me. Made a few typo corrections and some minor text changes from the first draft a few days ago, so I hope I have all of those fixed now ?

http://n9ewo.angelfire.com/ardv1.html

Also just updated (again) the Sangean DAR-101 MP3 recorder review. Some minor text changes plus added 4 internal photos (bottom of it’s page). I have never seen any internal photos anywhere on the internet of the DAR-101. Now there is.

http://n9ewo.angelfire.com/dar101.html

Again for reading any of my web pages, be sure and have your Pop Up stopper on FULL (do not allow ANY pop ups) and your security settings on your browser set at least to default. Otherwise Angelfire can be rather nasty with junk. If all else fails turn off your Java Script.

Many thanks for sharing, Dave!

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Radios: What are your daily drivers?

Many thanks to SWLing Post contributor, John C., who writes:

“Hi Thomas, I love [the SWLing Post] and have been meaning to thank you for all of the amazing reviews. Truly a treasure trove. But as I contemplate my next radio purchase I would like to know what radio you use more than any other. In other words…what’s your daily driver??? Enquiring minds want to know! Thank you. – JC”

Thanks for your question and the kind compliment, John.

Your inquiry is one I get quite a bit, so I hope you don’t mind if I share my response here publicly.

First of all, I should state that I don’t have a single “daily driver.”

Since I evaluate, test, and review radios I spend a lot of time with a variety of new receivers and transceivers.

I’m currently evaluating the Radiwow R-108, so it goes with me pretty much everywhere since I like to test receivers in a variety of settings. I’m also packing the Tecsun PL-310ET and the CC Skywave so I have units to compare with the R-108.

My Daily Drivers

Still, there are a number of radios in my life that get heavy use. Here’s my current list based on activity:

For Travel

When I travel, I reach for my favorite multi-function ultra-compact shortwave portable. In the past, I would have reached for the Grundig G6, the Sony ICF-SW100, the Tecsun PL-310ET, the Digitech AR-1780, or the C. Crane CC Skywave, Currently, I reach for the C. Crane CC Skywave SSB.

When I travel, I try to pack as lightly as I can–perhaps some would even call me a borderline travel minimalist. For example, when I fly to Philadelphia later this month for the Winter SWL Fest, I will take only one piece of luggage, a “personal carry-on” item: the Tom Bihn Stowaway, a pack the size of a small laptop bag. The Stowaway will contain my iPad, cords/accessories, and all of my clothes and toiletries for about 5 days of travel. As you can imagine, there’s not a lot of spare room in there for radio gear (quite the understatement).

I’ll still have room in my bag for the CC Skywave SSB, though, because the receiver is so compact. In addition, it’s a little “Swiss Army Knife” of a radio which covers the AM/MW, Shortwave, WX, and AIR bands.  It also has SSB mode and uses common AA batteries. The Skywave SSB is a welcome travel companion.

For Portable Shortwave DX

When I head to a park or go on a camping trip with the goal of doing a little weak signal DXing, I reach for a full-featured portable. In the past, I’ve relied heavily on the Tecsun PL-660 or PL-680, the Sony ICF-SW7600GR, and the Tecsun PL-880.

After acquiring the amazing Panasonic RF-B65 last year, it has become my choice full-featured portable. Of course, the RF-65B hasn’t been in production for ages, but thanks to a number of friends/enablers (including Dan Robinson and Troy Riedel) I finally found one for an acceptable price on eBay.

I’ve been incredibly pleased with the RF-B65’s performance and feel like I got a decent deal snagging one in great shape for less than $200. Only a few months prior to my purchase, it was hard to find good units under $300. Click here to check current prices, if interested.

For Morning News and Music

Since my staple morning news source, Radio Australia, went off the air, I spend a lot more time in the mornings listening to Internet radio mainly because I like listening to news sources that no longer, or never have, broadcast on the shortwaves.

Without a doubt, my favorite WiFi radio is the Como Audio Solo. I use it to listen to the CBC in St. John’s Newfoundland, The UK 1940s Radio Station, RFI MusiqueABC Radio Sydney, and a number of other news and music outlets.

The Como Audio Solo also serves as an audio feed for my SSTran AM Transmitter which then allows me to listen to all of this excellent content on 1570 kHz with vintage tube radios such as my Scott Marine SLR-M, my BC-348-Q, and my Minerva Tropicmaster.

For Mediumwave DXing

Without a doubt, my favorite radio for mediumwave/AM broadcast band DXing is the Panasonic RF-2200.

I mentioned in a previous post that my buddy Vlado (N3CZ) recently repaired, cleaned, and calibrated one of my RF-2200s.

Let’s just say that Vlado worked his magic and my RF-2200 now operates and performs like a brand new unit. Seriously. It’s simply unbelievable.

Not only does the Panny ‘2200 provide benchmark MW performance, it’s simply a pleasure to operate. It also produces some of the richest AM audio you’ll ever hear from a portable radio.

Of course, the ‘2200 hasn’t been produced in decades, so you’ll have to search for used ones on eBay, at hamfests, or through your favorite radio classifieds.

And, yes, I still need to finish a Part 2 blog-post about the ‘2200 repair–once I get a few details and photos from Vlado, I’ll post it!

Your Daily Drivers? Please comment!

Keep in mind that my “daily drivers” change quite a bit–the ones listed above are my current favorites and have been for a year or more.

So now that I’ve shared my daily drivers, I hope you will, too!

Is there a particular radio you reach for more than any other?  Please comment and tell us why it’s your favorite!


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

[Update: Please note that we’ve now posted a final review of the CTX-10 which builds upon the review below. Think of of the final review as the  second installment, or “Part 2? of this review. If you’re considering the purchase of a CTX-10 please read this initial review first.]

In the past two years few QRP transceivers have generated the interest of the CommRadio CTX-10. I’ve gotten no fewer than two dozen emails from readers asking about the CTX-10 after learning I had one here at SWLing Post HQ.  And, I’ll freely admit, I was among those people who couldn’t wait to give this promising little radio some on-air time––and, as a result, a proper evaluation.

The CTX-10 arrives in this simple box.

Everything included in the CTX-10 box.

There are a few reasons why the CTX-10 has stirred up so much excitement. Firstly, the CTX-10 transceiver is based on the excellent and well-regarded CommRadio CR-1/CR-1A receiver. Click here to read our review in a new window.

Fans of the US-made CR-1 and CR-1A appreciated the approach to the CommRadio design: simple operation, clever engineering, near-mil spec components and construction, superb receiver characteristics, as well as excellent audio. The classic CR-1 has all the essentials––multiple modes, filters, and the like––yet offers relatively few features when compared with other tabletop radios in its price class. It’s a simple get-on-the-air rig that feels like it’s engineered to last forever.  Indeed, its design approach reminds me of the Lowe receivers of days gone by.

Another reason for the unusual level of interest is that the CTX-10 has been in the works for a long time. It was first announced over two years ago in October, 2016, and only started shipping in July/August 2018.

Since then, there have been very few CTX-10 reviews posted…hence all of the email questions.

In early October 2018 Don Moore, President of CommRadio, sent me a loaner CTX-10 which I’ve been using regularly since, testing all aspects of this little 10-watt transceiver.

Even though I’ve had the radio for a while, I plan to post a final CTX-10 review in the SWLing Post in coming months. As you may know, I typically only keep a review unit two months before publishing an evaluation, so why the delay?  In short: I feel like the CTX-10 has some important updates/upgrades that need to come down the line, and I’m allowing time for these to be developed and tested before I issue a full and final review. So, if this is a rig that interests you, you’ll want to stay tuned for that.

In fact, due to a couple of quirks that only affected the first twenty production units, CommRadio has already replaced my initial review unit. I’ll detail these quirks below.

In the meantime, what follows is an initial review of the CommRadio CTX-10 with the most current firmware as of time of posting (1311). This review format is a departure from previous reviews as I’m only focusing on the pros and cons that might help future CTX-10 owners make a purchase decision.

Consider this initial review just a taste of the CommRadio CTX-10, not the full course.

CTX-10: The Pros

First of all, much like the CR-1 and CR-1A, the CTX-10 is an all-in-one unit that takes fewer than five seconds to get on the air if you have an antenna at the ready. Seriously. Other than a key, and/or microphone and antenna, there are no other external attachments needed. It’s field-ready from the moment you remove it from the package.

True story: it took me all of thirty seconds to remove the CTX-10 from the box, plug in a key, an antenna, and have it on the air.  This is a major pro, in my radio world.

ATU

The CTX-10 has a built-in automatic antenna tuner that seems to do a great job making 1:1 matches on near-resonant multi-band antennas. I have a large horizontal multi-band delta loop here at the QTH, and the CTX-10 does a fine job finding a match on most ham bands.

Can it match the performance of the Elecraft KX-series ATU? I haven’t done an A/B comparison yet, but I don’t expect so—not on random wire antennas, at least. I do think, however, it will easily match any proper field antenna you pack in your go-kit.

Another minor plus worth mentioning? The ATU is very quiet in operation.

Internal batteries

The CTX-10 ships with three built-in #18650 3.7V 2600 mAh rechargeable Li-ion batteries that are user-replaceable. These are high-capacity cells—in fact, the same type of cells used in the Tesla Model S.

But how do they work? In short: brilliantly. They power the CTX-10 for a much longer period of time than the battery pack in my Elecraft KX2.

After a full charge, these cells will support casual operation for up to eight hours. If you’re using the CTX-10 in a contest or on Field Day where operation is intense––that is to say, near-constant transmitting––it should last the better part of an hour. Don Moore actually produced a video early on of the CTX-10 running a full 10 watts and transmitting dits in CW for forty solid minutes before the batteries depleted to the point of shutting down. That’s certainly a new benchmark for portable rigs with internal batteries.

The CTX-10 has an intelligent charger that will recharge the internal cells when any voltage over 5 VDC is applied. This means, in a pinch, even a typical USB charger will work. If the power supply can deliver up to ten watts, it’ll charge the batteries rapidly––anything below that will take a longer.

Elecraft KX2 (left) and the CommRadio CTX-10 (right)

I also own the Elecraft KX2 and have used it in the field more than any other portable transceiver I’ve owned up to this point.

The KX2’s battery charging routine is more involved than that of the CTX-10. The KX2’s pack must be removed from the radio (by opening the bottom plate of the chassis with two thumb screws, and unplugging the coaxial connector), then it must be hooked up to an external battery charger, charged, and then re-inserted in the KX2.

In contrast, the CTX-10 only requires plugging it into a power source that can provide anything from 5 – 20 VDC––in other words, pretty much any power source. All of the intelligent charging is built into the CTX-10.

Without a doubt, the CTX-10 has the most robust and well-designed internal battery charging system I’ve ever found in a portable radio. Period.

Best-in-class duty cycle

If you’re a fan of FT-8 and other high-duty cycle digital modes, you’ll be very pleased with he CTX-10.

Like many other hams, I was bitten by the FT-8 bug. FT-8 is an amazingly efficient digital mode that somehow manages to defy propagation—even when transmitting at low power. In the past, I’ve worked all time new countries on five watts!

The CTX-10 back panel.

At home, I designated the Elecraft KX3 as my primary FT-8 rig. First time putting it on the air, I found to be fairly effortless. However, after operating perhaps 15-20 minutes, I found that power levels decreased significantly. This is because taxing the finals with FT-8 produces a lot of heat, and the KX3 protects the finals by lowering the output power. KX3 owners wishing to play FT-8 for extended periods at 10 watts or higher know how important it is to purchase an aftermarket heatsink to give the KX3 more transmitting time.

The CTX-10, in contrast, needs no aftermarket additions—if anything, it’s over-engineered. The entire chassis of the radio is essentially a heat sink, and because of this, it requires neither additions nor a fan to cool the finals, leading to comparatively effortless operation. Plus, as a result, operation is completely quiet.

In short? No overheating finals with the CTX-10: it’s an FT-8 beast!

Receiver performance

Overall receiver performance is what I expected: identical to the CommRadio CR-1/CR-1a receiver series with the added benefit of an internal ATU that helps tweak the antenna match on the ham bands. A very good thing.

In addition, the CTX-10 has custom multiple preselectors to assist in ham radio operation and broadcast listening. Though I haven’t tested the CTX-10 in RF-dense environments like Field Day, I expect it should hold its own.

Both sensitivity and selectivity are excellent. The receiver also has a very low noise floor and produces excellent audio fidelity especially when paired with headphones or an external speaker.

In general, I prefer the CTX-10 audio characteristic over that of the Elecraft KX series.

Simple operation

You can tell that CommRadio has a legacy in designing equipment for the military, as well as for commercial and aviation industries. The CTX-10 smacks of a channelized commercial radio. There are relatively few features and adjustments as compared with, say, the Elecraft KX2 or the LnR LD-11. For those who like basic controls, the CTX-10 should please. On the other hand, if you like more granular control of your transceiver, you might prefer more refinements.

Quality engineering and construction

Like the CR-1A, the CTX-10 enclosure is aluminum with machined aluminum knobs. The boards and internal components are near (if not) mil-spec––brilliant quality that is found in few other radios.

The OLED display is easy to read at any angle and under almost any conditions you might experience at home or in the field––truly best-in-class in this regard. It is a relatively small display, but crisp and high-contrast, so quite easy on the eyes.

The circuit boards inside are of the highest quality, and so are the components. Don Moore sourced them from the same suppliers he uses for commercial-grade equipment.

My good friend, Vlado (N3CZ)––radio engineer and repair technician––took a look inside the CTX-10 chassis; he was sincerely impressed by the quality of the construction and board design. It’s worth noting that Vlado isn’t easily impressed, as he looks at the internals of commercial and military grade communications equipment every day: thus it says something that he remarked on this rig’s quality.

CTX-10: The cons

I’ve covered the obvious positives, so what about the negatives?

What follows are the cons I’ve noted while operating the CTX-10.

Keep in mind, some of these cons may disappear with future CTX-10 firmware updates. Again, I plan to hold off on my full and final CTX-10 review until I feel CommRadio has essentially finished planned upgrades.

At least for now: only one VFO

[Update: A/B VFOs and split operation were added to the CTX-10 via a firmware update in 2019. Please read our final review for details.]

Herein lies my biggest gripe with the CTX-10 and what I would consider a glaring omission on a $1,000 modern SDR transceiver.  However, it’s worth noting that CommRadio has committed to address this in an update–see below.

At time of posting, the CTX-10 doesn’t have A/B VFOs like almost all modern transceivers––certainly like all of its direct QRP competitors, like the Elecraft KX2/KX3, LnR LD-11, and Yaesu FT-818/817ND.

So, how does a lack of two VFOs impact operation? First of all, there is no way to operate split on the current version of the CTX-10. Ouch.

The first time I put the CTX-10 on the air it was at the QTH of Vlado (N3CZ). We put the CTX-10 on 40 meters, and one of the first stations we heard was in Vanuatu, due to a brilliant opening into the Pacific. Vlado was positive he would work them with 10 watts on his 40M Steppir Yagi––I was, too. This being the first time either of us attempted DX on the CTX-10, we plugged in Vlado’s Bencher paddles and quickly tried to sort out where the DX station was working his pileup.

It was then we realized that the CTX-10 had no second VFO to work split, and, hence, we couldn’t work the Vanuatu station––because, like pretty much any desirable DX, he was operating split. Frankly, I was in disbelief and quickly downloaded the latest CTX-10 manual to find out how to engage split, but there was no mention of it in the manual.

The only other option was to operate split using a RIT control to shift the receive frequency. Again, we couldn’t locate a RIT control and a search of the manual proved no mention of RIT because, alas, there is no RIT control.

Again, we couldn’t work Vanuatu on the CTX-10 because, like all good DXers, the Vanuatu team were operating split.

Update: CommRadio has informed me they will be adding A/B VFOs as soon as possible, certainly before the 2019 Hamvention in mid-May, but hopefully sooner.

Update 2: Split operation added June 2019. Please read our final review for details.

Features may be too basic for some ham radio operators

It’s no secret: most of us hams like to fiddle with controls to tweak a transceiver’s performance. This is why ham radio transceivers often feature even more controls than their commercial/military counterparts.

The CTX-10 support feet are easy to flip up. The operating angle is excellent.

Still, some operators do appreciate a simpler rig, as they prefer simply to get on the air and get the job done. I appreciate this, too, especially when engaged in field operations where I’m less inclined to tinker with settings. So there’s some appeal in the CTX-10 approach.

At present, the CTX-10 feature set is very basic. Here’s a list of common controls the CTX-10 lacks––many that I’d typically expect in a radio of this price class:

No RF Gain control. The CTX-10’s RF gain is directly tied to the three AGC settings (slow, medium and fast). I know operators who never reach for the RF gain control, but I do, especially in the summer when it’s such an effective tool to lower QRN levels and help DX pop out of the background.

No microphone gain control. The CTX-10 lacks a mic gain control. The microphone input has a limiting pre-amplifier with built-in compressor and ambient noise gate. Problem is, at present, these settings are fixed and cannot be manually adjusted by the user. The CTX-10 was designed to work with handheld mics positioned closely to one’s mouth. Early feedback from users indicated that the CTX-10 was a little too aggressive, cutting off speech; a recent update did address this concern. Some users might never notice the lack of a mic gain control if they stick with the suggested modular MFJ-290MY or Yaesu MH-31A8J handheld mic. Personally, though, I like having a little more control of my microphone performance.

Keep in mind, there’s a plus side to the CommRadio ANG (Ambient Noise Gate): extended battery life. If you have the microphone keyed down, yet aren’t speaking for longer than a second or two, the output will be gated OFF, preventing background ambient noise from being transmitted. The on/off gating happens very quickly and isn’t noticeable.

The CTX-10 currently has no passband (PBT) control, notch filter or noise blanker.

Microphone compression is also pre-configured, and there’s currently no way to manually adjust it. This is a design choice typical of commercial communications gear.

No QSK/full break-in operation. The CTX-10, like the LnR LD-11, uses a traditional relay for switching between transmit and receive. Some CW ops like to hear the received audio between the dits and dahs of their sent CW. Elecraft radios, for example, use PIN diode T-R switching to eliminate relays during QSK. The CTX-10 uses a relay, so during CW operations, you’ll hear the 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.

Limited CW adjustments. The CTX-10 lacks other controls many of us CW operators appreciate. Currently, the CTX-10 lacks a sidetone control––you cannot change the sidetone volume, nor can you turn it off. I believe CommRadio plans to fix this quirk in a future firmware upgrade. Additionally, you (currently) can’t change which side of your paddle sends dits and dahs without re-wiring your paddle. A minor con, for sure. Still, most modern QRP transceivers allow you to change this from the radio––I imagine CommRadio could add this feature in the future if their customers want it.

In addition, when operating the built-in CW keyer at speeds north of 25 words per minute, both Vlado and I noticed that immediately following a TX-RX-TX relay recovery, CW keyer timing was a little flaky. We assumed there was a problem with our paddles (perhaps dirty contacts?), but that turned out not to be the problem. Difficult to characterize, but essentially: immediately after a TX-RX-TX relay recovery, it’s hard to form a word correctly. The letter “Y” might come out as a “K” or “X” and  a “Q” might come out as a “Z.” Both Vlado and I believe this might have something to do with keyer timing, which is possible. Nonetheless, I’m confident this can be fixed with a firmware update. In addition, we worked my friend Mike (K8RAT) and while he had very positive comments about the CW tone in general, he did notice truncated elements following a TX recovery. He also noticed an occasional slight tone spike on the first element which seems to coincide with an audio pop we hear in the sidetone. Note: CommRadio fixed this issue in a 2019 firmware update. Read our final review for details.

Accident-proof ATU activation. As with the CR-1A receiver, most of the CTX-10’s features and options are controlled by accessing the menu system by pressing the volume control knob. To make ATU activation easy, CommRadio place the ATU function first in the menu––with one knob press, the ATU item appears, and with one more press the ATU activates and tries to find a match. Engaging the ATU, in my opinion, is just a little too easy. With two presses of the volume knob, the ATU engages––great, but I find this happening by accident simply by normal handling of the radio. Instead of two short presses to engage ATU, I feel it might be best when making one short then one long press.

One other minor note: the CTX-10 ATU configuration cannot be adjusted manually like it can on the Elecraft KX series ATU.

No keylock to prevent powering up and engaging ATU. The CTX-10 does have a keylock to prevent the encoder from shifting during operation (a great feature for FT-8, for example), but it lacks a keylock to prevent the main power button from being pressed and turning on while in transport. Even more worrisome would be turning on the unit and engaging the ATU while in a pack––I’m guessing this could eventually damage the radio’s finals. The current solution for this? CommRadio suggests tying a shielded wire around the post of the volume control. This prevents accidental pressing while in transport and the CTX-10 ships with one of these around the volume knob (to prevent it turning on in shipment). I feel a more elegant solution would be to design it so that, in order to power up the CTX-10, you’d press two buttons simultaneously: for example, the volume control and the STEP buttons. I’ve make this suggestion to CommRadio. Update: Via a 2019 firmware update, CommRadio added a feature that automatically turns off the radio if accidentally turned on during transport. This is not a keylock and will not prevent the ATU from activating of the power button is accidentally pushed twice, but it will prevent the radio from being powered on in a pack until the batteries have been depleted.

Minor concern: no noise reduction control. In truth, this is a very minor con in my opinion. I’m not a big user of DSP noise reduction, but some users expect it on modern transceivers. I feel like the CTX-10’s receiver is well-balanced so I wouldn’t reach for a noise reduction control under normal operating conditions.  That said, since there is no manual RF gain control, a variable noise reduction control could come in handy when QRN is heavy.

Size comparison: My ultra-compact C. Crane CC Skywave SSB sitting on top of the CommRadio CTX-10.

Minor concern: limited power output levels. This is a very minor gripe for me, but again could be important for other ops. At present, the CTX-10 has only three power output levels: 1, 5, and 10 watts. Thus for low-power contests, there is no way to lower the CTX-10 below one watt and no adjustment to zero watts. A couple of years ago my radio club had a DXCC 500 mW challenge to see who could work 100 countries with 500 mW or less. Most other modern QRP transceivers in this class have more nuanced control of power output and can be set to 1/2 watt.  At present, the CTX-10 cannot. This is truly a minor complaint––perhaps only important to 10% of CTX-10 owners at best––but I’m willing to bet this could be added via a firmware upgrade.

Early production run quirks now resolved

Fortunately, however, the CTX-10 is listening to their market, and has resolved a number of early production run quirks. My initial evaluation loaner unit was serial number #19. Turns out, some of the first production run units (including mine) had a couple of hardware quirks. CommRadio has replaced or fixed these issues when customers report them, and units currently in inventory aren’t affected. I list them here simply to document:

  • Resolved: Intelligent charger whine. When charging the internal Li-Ion cells, my evaluation unit produced a high-pitched audible whine. I measured the audio frequency with a simple smartphone app and determined that it hovers around 10.5 kHz. The replacement unit doesn’t have this problem.
  • Resolved (or repairable): Internal speaker distortion. The internal speaker on some of the early units was prone to vibrate against the bottom plate of the radio’s chassis. This produced a buzzing distortion on loud sounds or when the volume was increased above, say, 50%. Again, this only affected some of the initial production run units. The fix for this is quite easy, and either CommRadio will do this for you or you can do it yourself and get a warranty extension, so if you find this to be a problem with your early unit, contact CommRadio.

Conclusion

To my knowledge, the CTX-10 is CommRadio’s very first ham radio transceiver.  But it’s not the company’s first foray into transceiver equipment, as they’ve a solid history in commercial, aviation, and military electronics.

My biggest criticism of the CTX-10 is that I feel it should have never been released without A/B VFOs. Fortunately, this was addressed in a 2019 firmware update. I trust this company, so I know they will follow through; I’ve even offered input on how split operation might be implemented with the A/B VFOs. Personally I wish the rig sported a little more in the way of CW controls, mic gain, and an RF gain control, too––but that’s my preference, controls I like to use. Again, the CTX-10 feature set might be a little too thin––too simplistic––for some hams.

That said, I never expected the CTX-10 to have the number of features that, say, the KX2 has––the CTX-10 isn’t intended to be a “Swiss Army Knife” radio like the KX2/KX3. In fact, CTX-10 development actually began around the same time the KX2 was introduced to the market, and its introduction didn’t deter CommRadio.

CommRadio firmly believes that the CTX-10 will still have appeal to current KX2/KX3 owners and QRPers who value their design philosophy of simplicity. And, what’s more…they have a point.

So, who is the CTX-10 for?

When I check out a new-to-the-market radio like the CTX-10, I always try to sort out who the customer is––what type of ham radio operator would reach for the CTX-10 over other transceivers.

After having spent the past few months with the CTX-10, I can tell you that the CTX-10 owner is one who values a very simple, straightforward radio––one that appears and functions more like a commercial or military channelized set. 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.

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

The whole body of the CTX-10 is essentially a heat sink.

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

  • 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
  • A high duty cycle and no cooling fan noise or third-party heat-sink add-ons
  • Digital modes like FT-8 and the ability to operate them in the field from internal batteries
  • The equivalent of a simple portable military/commercial set
  • Robust audio from a radio’s internal speaker or headphones
  • A well-balanced receiver with few manual adjustments
  • Broadcast listening (the CTX-10 is also superb broadcast receiver)
  • Best-in-class hardware

The CTX-10 is built like a tank, and has brilliant receiver characteristics. It’s also designed and manufactured here in the USA, and I find it’s easy to get good support from CommRadio.

I will add that CommRadio has been very receptive to my constructive and frank criticism. A good thing, in my book, as lesser companies might take offense or simply be dismissive.

If you’ve been waiting to purchase the CTX-10, I hope I’ve given you enough information that you can make a decision.

If you have any specific questions, please contact CommRadio or comment, and I’ll do my best to answer. I hope to post a few videos of the CTX-10 in action within the next few weeks when my rather busy schedule permits.

Please click here to read our final review of the CommRadio CTX-10.

Click here to view the CommRadio CTX-10 at CommRadio and at Universal Radio.

For a full list of CTX-10 features and specs, I would encourage potential owners to download and read the CTX-10 Operator’s Manual, available on the CommRadio website.


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Critical reviews of the $37 HanRongDa HRD-737 shortwave radio

Many thanks to SWLing Post contributors Glen and James Fields who shared their experience after  publishing a post about the HannRongDa HRD-737 portable radio.

Glen writes:

I received one Saturday I had ordered from Aliexpress. In one word, avoid. The performance is really terrible everywhere except the FM broadcast band. Reception there is OK, but it is prone to overload more than my other radios. Aircraft reception is terrible. Only very strong shortwave signals are present. Same with AM broadcast. VHF performance is abysmal. To illustrate, my closest NOAA transmitter is so strong it trips the “close signals” quick scan in my Whistler TRX-1. On the HanRongDa, the NOAA signal is present, but it’s weak. All my other weather band receivers can get signals on all 7 frequencies. The HanRongDa hears only the very close one. This is easily the worst receiver I’ve ever gotten. Perhaps it’s defective. Eager to hear experiences from anyone else.

James Fields writes:

Received mine yesterday. Have only tested in my office which is a challenging, RFI-rich environment, so trying to withhold final judgement. However so far my experience matches Glen’s. Can only pick up the strongest shortwave signals. MW AM so far terrible. FM broadcast passable but not at all remarkable, and most stations have a LOT of hiss in the background. Have yet to pick up AIR band transmission on frequency that I can get on every other receiver I have. Nothing on CB yet. Cannot receive any NOAA frequencies, including two that I get solidly on other radios. Interestingly I can receive local police dispatch frequency pretty well.

Construction is pretty cheap.

Positives? I got mine for $37 shipped from a reseller on Ali Express . If I had paid over $40 I would feel worse about the value. And it really is a shirt-pocket portable. Super small and light.

At this time I cannot recommend this for anyone, for any purpose.

Thank you for sharing! I think I’ll pass on the HanRongDa HRD-737!

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Tivdio V-115/Audiomax  SRW-710S: Keith approves of everything save battery performance

Many thanks to SWLing Post contributor, Keith Stephens, who writes:

Regarding the Audiomax  SRW-710S  radio.

I was very pleasantly surprised at more than one aspect of this radio.  First, it sounds like something with a much larger speaker.  It has the base capability of at least a 6″ speaker.  My favorite FM music station comes from a mountaintop repeater over 70 miles away.  The 710S is one of two radios I have tried through the years that brings it in clear and clean.  The other is a much bigger more expensive radio.  And of course, the voice quality of the local AM talk shows is excellent.  I lost my instruction booklet (as usual) but I do want to record the FM station for times when I am out of range.

It is a pity that I have to tell of a bad shortcoming on this wonderful radio.  Alas, I couldn’t believe it the first time it died at the end of three hours.  I thought I had a bad battery, but a fully charged new battery only lasts 3 hours!  I would pay twice the price for the same radio if it had a better battery life.  Please let me know if there is a better battery or the same radio with a larger battery.

Thanks for your mini review, Keith! Admittedly, I’ve never tested the battery performance of this set because I typically use it for short (1 hour) recording sessions.

Click here to read other reviews of the Audiomax  SRW-710S/Tivdio V-115.

Retailers:

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