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Many thanks to SWLing Post contributor, Dave Zantow, who notes that Reuter Elektronik recently introduced their latest radio: the RDR52 QRP Transceiver.
The RDR52 can basically be seen as a desktop version of the popular Reuter Pocket mobile device. Astonishingly, the Pocket is often used as a full-fledged desktop receiver. Many operators report that they have sold their “large” devices and now only use the Pocket because it pairs good reception properties with simple operation and offers a very effective spectrum display while keeping the power consumption to a minimum.
However, the battery-powered Pocket was never designed for that purpose. First, it needs a stand-up aid to be easy to operate on your desktop (display almost vertical). Second, the playback volume of the loudspeakers is low and turning the scroll wheel feels finicky. Third, operation on a constant charging current supply is suboptimal for the built-in batteries: Constant full charging shortens their service life.
The RDR52 avoids these disadvantages. It essentially contains the circuit and thus the display and reception properties as well as the operating options of the Pocket. Due to the larger housing (heat dissipation) and a slightly higher possible current consumption (no batteries as power supply), improvements in the IM behavior (more powerful preamplifiers and AD converters) could be achieved. Other differences to the Pocket include:
Aluminum profile housing 190 x 90 x 100 mm³ with 5 mm thick front and 2 mm thick rear panel, powder-coated / anodized.
BNC sockets for antenna connection, separate for 0 – 71 MHz, FM / 2m / DAB and exciter / QRP transmitter.
Large rotary knob with solid optical rotary encoder.
Additional rotary knob for volume adjustment of headphones and loudspeakers.
Two 32 mm loudspeakers with good bass reproduction.
External power supply DC voltage 9 – 15 V (common hollow pin socket with 2.5 mm pin).
All the Pocket’s enhancements are also available for the RDR52 (broadband spectrum with up to 52.6 MHz display width, 8 different FM filters for extreme DX to high-end stereo, up to 16 GBit flash memory for audio or I/Q recordings, screen dump of the display to the recorder, WiFi, Bluetooth, power supply and control of the RLA4 / RFA1 directly from the antenna input, …). Two basic hardware versions will be available: Standard black with simple loudspeakers and plastic knobs, or a special version with metal knobs and aluminum loudspeaker membranes.
The equipment of different transmitter modules and frequency ranges has been a bit expanded in contrast to the Pocket. Two modules can be installed in the RDR52 at the same time (Pocket: only 1 module). This means, for example, that the FM module and the SW QRP transmitter can be installed at the same time, or the broadband exciter can be installed without the need for an FM module. However, equipping both transmitter modules (exciter and QRP transmitter at the same time) is not possible.
The RDR52 is in production and is expected to be available from the end of December 2021. Prices according to the current price list.
Based on the price list, it appears the RDR52 will start at € 999 with a number of optional upgrades/configurations.
It sometimes seems that one of the biggest enemies of a radio enthusiast these days is RFI (radio frequency interference), which is to say, human-originated noise that infiltrates––and plagues––vast chunks of our radio spectrum.
Yet I believe RFI has, in a sense, also managed to energize––and even mobilize––many radio enthusiasts. How? By drawing them out of their houses and shacks into the field––to a local park, lake, river, mountain, woodland, or beach––away from switching power supplies, light dimmers, street lights, and other RFI-spewing devices.
Shortwave and mediumwave broadcast listeners have it easy, comparatively speaking. They can simply grab a favorite portable receiver, perhaps an external antenna, then hit the field to enjoy the benefits of a low-noise environment. In that a portable receiver is something of a self-contained listening post, it’s incredibly easy to transport it anywhere you like.
Ham radio operators, on the other hand, need to pack more for field operations. At a minimum, they need a transceiver, an antenna, a power source, not to mention, a mic, key, and/or computing device for digital modes. Thankfully, technology has begun miniaturizing ham radio transceivers, making them more efficient in the use of battery power, and integrating a number of accessories within one unit.
Photo from the 2019 Tokyo Ham Fair
Case in point: in 2019 at Tokyo’s Ham Fair, Icom announced their first QRP (low-power) radio in the better part of two decades: the Icom IC-705.
Introducing the Icom IC-705
It was love at first sight among fans of Icom when the 2019 announcement was made. Why? The instant thrill came courtesy of the IC-705’s resemblance––in miniature––to the IC-7300, one of Icom’s most popular transceivers of all time. Not only that, but the IC-705 sported even more features and a broader frequency range than the IC-7300. What wasn’t to love?
But of course, unlike the IC-7300, which can output 100 watts, the IC-705’s maximum output is just 10 watts with an external 12V power source, or 5 watts with the supplied Icom BP-272 Li-ion battery pack. Nevertheless, enthusiasts who love field radio––this article’s writer being among them––were very pleased to see Icom design a flagship QRP radio that could take some portable operators to the next level. Power was traded for portability, and for field operators, this was a reasonable trade.
And since, again, the IC-705 has even more features, modes, and frequency range than the venerable IC-7300, I felt it important to note them up front. Here are a few of its most notable features, many of which are not available on its bulkier predecessor:
VHF and UHF multimode operation
D-Star mode
Built-in GPS
Built-in Wifi connectivity
Built-in Bluetooth connectivity
Portable size
Battery power
The receiver design is similar to the IC-7300 below 25 MHz in that it provides a direct conversion. Above 25 MHz, however, it operates as a superheterodyne receiver. While the user would never know this in operation, it’s a clever way for Icom to keep costs down on such a wideband radio.
At time of publishing, there are no other portable transceivers that sport all of the features of the Icom IC-705. It has, in a sense, carved out its very own market niche…At least for now.
I’ve owned the IC-705 since late September 2020, and I still haven’t fully explored this radio’s remarkable capabilities. It’s really a marvel of ham radio technology, and I’m having fun exploring what it can do.
One conspicuous omission
Let’s go ahead and address this promptly. The IC-705 does have one glaring shortcoming. It lacks one feature that is standard on the larger 100-watt IC-7300: an internal antenna tuner (ATU).
To be frank, I was a little surprised that the IC-705 didn’t include an internal ATU, since it otherwise sports so many, many features. Not having an internal ATU, like a number of other general coverage QRP transceivers in its class, definitely feels like a missed opportunity. With an ATU, the ‘705 would truly be in a class of its own.
I’m sure Icom either left the internal ATU out of the plan due to space limitations––perhaps wanting to keep the unit as compact as possible?––or possibly to keep the price down? I’m not sure. At release, the price was $1300 US, which is undoubtedly on the higher side of this market segment; at that price point, it might as well have included an ATU.
With that said, not having an internal ATU is still not a disqualifier for me. Why? Because I have a number of resonant antennas I can add on when in the field, a remote ATU at home, and a couple of portable external ATUs, as well. Yes, it would be helpful to have it built in––as on my Elecraft KX1, KX2, and KX3, or on the ($425) Xiegu G90––but for me it’s not a deal-breaker.
One other minor omission? A simple tilt stand or foot. I do wish Icom had included some sort of foot on the bottom of the IC-705 so that it could be propped up for a better angle of operation. Without a tilt stand or foot, the IC-705 rests flat on a surface, making its screen a bit awkward to view. Of course, a number of third-party tilt stands are available on the market. And if you have a 3D printer or access to one, you can find a wide variety of options to simply print at home. I printed this super simple tilt foot, which works brilliantly.
But why not include one, Icom?
My 3D printed tilt foot
But while the IC-705 lacks a tilt foot, it actually sports a number of connection points on the bottom, including a standard tripod mount. Thank you, Icom, for at least including that (other radio manufactures please take note)!
Initial impressions
Funny: the IC-705 is the first new transceiver I’ve purchased with a color box.
If you’ve ever owned or operated the Icom IC-7300, you already know how to operate many of the functions on the IC-705. The user interfaces on the touch screens are identical. Features that are unique to the IC-705 are easy to find and follow the same standard Icom user-interface workflow.
Having less front faceplate real estate, the IC-705 has less buttons than the IC-7300––about 11 less than its big brother, to be exact. However, the twin passband, gain, multi-function knob and encoder are in the same positions and layout as on the IC-7300.
And if you’ve never used an IC-7300 before, no worries: this is one of the more user-friendly interfaces you’ll find on a ham radio transceiver.
The build of the IC-705 is excellent. It’s not exactly hardened for the elements––there is no waterproof rating or dust rating, for example––but it gives the impression of a solid little radio, likely to withstand a bit of less-than-delicate handling. Yet even though it’s designed to be a portable field radio, I’ll admit that the front panel and especially the color touchscreen feel a little vulnerable. I do worry about damaging that touchscreen while the radio travels in my backpack.
The Icom LC-192
On the topic of backpacks, Icom released a custom backpack (the LC-192) specifically for the IC-705, Icom AH-705 ATU, antennas, and accessories. I did not consider purchasing this backpack, although I’m sure some operators would appreciate it, as it has dedicated compartments for supplies and the radio can be attached to the floor of the backpack’s top compartment. Again, I passed because I’m a bit of a pack fanatic and tend to grab gear that’s more tactical and weatherproof.
IC-705 and Elecraft T1 ATU at Toxaway Game Land
While its in my Red Oxx or GoRuck backpack, I house the IC-705 in a $14 Ape Case Camera insert. Eventually I want to find a better solution, but this does help pad the IC-705 while in my backpack and certainly fits it like a glove––hopefully protecting that touchscreen.
A number of third-party manufacturers have designed protective “cages” and side panels for the IC-705, but I’ve been a bit reluctant to purchase one because I feel they may add too much weight and bulk to the radio.
To the field!
Sandy Mush State Game Land
The day after I received my Icom IC-705, I took it to the field to activate Sandy Mush State Game Land for the Parks On The Air (POTA) program. Typically, when I review a new radio, I spend a few hours with it in the shack before taking it to the field. In this case, however, I felt comfortable enough with the IC-705 user interface, so I decided to skip that step entirely––I was eager to see if this little radio would live up to expectations.
The previous evening, I’d connected the IC-705 to my 13.8V power supply, so the BP-272 battery pack was fully-charged and attached to the IC-705. There was no need for an external battery to be connected.
Getting on the air that day was very straightforward; indeed, the set-up couldn’t have been more simple: radio plus antenna. I connected the IC-705 to a Vibroplex EFT-MTR end-fed 40, 30, and 20-meter resonant antenna, thus an external antenna tuner was not required.
The Vibroplex/End-Fedz EFT-MTR antenna
Next, I plugged in the included speaker/mic, spotted myself to the POTA network, and started working stations. I asked for audio reports and all were very positive using only the default audio settings. Obviously, the small hand mic works quite well. I did quickly decide to unplug one of the two connectors of the speaker mic (the speaker audio side) so that the received audio wouldn’t be pumped through the hand mic, using the much better IC-705 front-facing speaker.
In the field that day, I had a few objectives in mind:
See how well the supplied hand mic works for SSB contacts, thus intended to ask for audio reports
Check out full break-in QSK operation in CW mode
Measure exactly how long a fully-charged Icom BP-272 Li-ion battery pack would power the IC-705 under intense operation
SSB
SSB at Lake Norman State Park
I was very quickly able to sort out how to record and use the voice memory keying features of the IC-705. There are a total of eight memory positions that can be recorded to the internal microSD card. It’s very simple to use one of the memories in “beacon” mode––simply press and hold one of the memory buttons and the recording is transmitted repeatedly until the user presses the PTT to disengage it. This is incredibly helpful when calling CQ; I typically set mine to play “CQ POTA, CQ POTA, this is K4SWL calling CQ for Parks On The Air.” I’ve also set a five-second gap between playback, allowing for return calls. As I’ve mentioned before, voice-memory keying is incredibly useful and saves one’s voice when calling CQ in the field.
The voice and CW-memory keying features of the IC-705 are robust enough that they could be used in a contest setting to automate workflow. One important note: voice-memory keying saves recordings to the internal MicroSD card. If that card is removed, formatted/erased, or if the file structure is altered, the voice-memory keyer will not recall recordings.
CW
CW at South Mountains State Park
Next, I plugged in my paddles and started calling “CQ POTA” in CW.
As with the voice-memory keyer, CW-memory keying was incredibly easy to set up. Once again, the user once has eight memory positions. As the keyer plays a pre-recording sequence, the IC-705 will display the text being sent.
One of the questions I’m asked most by CW operators about the IC-705 is whether the radio has audible relay clicks during transmit/receive switching. Radios with loud relay clicks can be distracting. My preference these days is to operate in full break-in QSK mode, meaning, there is a transmit/receive change each time I form a character––it allows me space to hear someone break in, but results in much more clicking.
The IC-705 does have relay clicks, but these are very light––equal in volume to those of other Icom transceivers, neither louder nor softer. These clicks, fortunately, are not too distracting to me, and to be fair, I find I don’t even notice them as I operate. With that said, transceivers like my Elecraft KX2 and Mission RGO One use PIN diode switching, which is completely quiet.
Battery Life
Tapping the battery icon will open a larger battery capacity monitor.
My third objective at the first field outing was to test how long the Icom BP-272 Li-ion battery pack would power the IC-705 while calling CQ and working stations in both SSB and CW for an entire activation.
After nearly two hours of constant operation, the BP-272 still had nearly 40% of its capacity.
I didn’t expect this. I assumed it might power the IC-705 for perhaps 90 minutes, max. Fortunately, it seems at 5 watts, one BP-272 could carry you through more than one POTA or SOTA (Summits On The Air) activation. I was pleasantly surprised.
Four months later…
POTA activation at Tuttle Educational State Forest
Since that initial field test, I’ve taken the IC-705 on easily thirty or more individual POTA activations. I’ve also used it at home to chase POTA stations and rag chew with friends.
In short, I’ve found that the IC-705 is a brilliant, robust portable transceiver for SSB and/or CW and a pleasure to operate.
Herein lies the advantage of purchasing a radio from a legacy amateur radio manufacturer: it’s well-vetted right out the door, has no firmware quirks, and is built on iterations of popular radios before it.
I’ve found that IC-705 performance is solid: the receiver has a low noise floor, the audio is well-balanced, the AGC is stable at any setting, and it’s an incredibly sensitive and selective radio.
Digital modes
POTA activation at Lake Jame State Park
One huge advantage of the IC-705 is that it, like the IC-7300, has a built-in sound card for digital modes. This eliminates the need for an external sound card interface. After you’ve read the installation guide, and installed Icom’s USB drivers, simply plug the IC-705 into your computing device via USB cable and you can directly control the ‘705 with popular applications like WSJT-X.
I have not used the IC-705 for digital modes while in the field, but I have done so in the home shack. It was one of the easiest radios I’ve ever set up for FT8 and FT4.
I’m not the biggest digital mode operator, but if you are into it, I expect you’ll be very pleased with the IC-705. It must be one of the most portable, uncomplicated transceivers for digital mode operation currently on the market. I know a number of POTA activators have been using the IC-705 for FT8 and FT4.
D-Star
Being perfectly honest here, I have a chequered history with the D-Star digital voice mode. I purchased an Icom ID-51a and D-Star hotspot several years ago because a local ham pretty much convinced me it was the coolest thing since sliced bread.
And in truth? It is rather amazing.
But at the end of the day I had to admit to myself that I’m an HF guy, and found the user interface and operating procedures just a bit too other-worldly. I kept the ID-51a for perhaps a year, then sold it, along with the hotspot.
Although I knew the IC-705 had D-Star built in, I really hadn’t given it a second thought. But since I’m a reviewer, I simply had to check it out. I still had my D-Star credentials from some years ago, so I set up the IC-705 and connected the transceiver to the Diamond dual band antenna on top of my house.
Fortunately, I was able to hit our only local D-Star repeater and connect on the first go. Note that, like the ID-51a, the IC-705 can use your GPS coordinates, then automatically find the closest D-Star repeater and load the frequency and settings from the default database on the IC-705 MicroSD card.
After reviewing a YouTube video demonstration, I was on the air with D-Star and found the user interface much easier to use than that of the ID-51a. It really helps having a large touch screen.
I’ll admit it: I’m warming back up to D-Star, and I have the IC-705 to thank for that.
Some day, I plan to use D-Star on HF, as well. I acknowledge that it might take some pre-arranging, but perhaps I could even make a D-Star POTA––or better yet, SOTA––contact, if the stars align. It’s certainly worth the experiment.
Let’s talk about broadcast listening
Radio Exterior de España’s interval signal on the IC-705’s waterfall display
Although I’m a pretty active ham radio operator, I’m an SWL and broadcast listener at heart. One of the appealing things about the IC-705 is its excellent receiver range (0.030-470.000 MHz) and multiple operating modes, as well as its adjustable bandwidth. Broadcast listeners will be happy to know that the AM bandwidth on the IC-705 can be widened to an impressive 10 kHz, which is certainly a stand-out among general coverage transceivers.
After turning on the IC-705 for the very first time, I tuned to the 31-meter band and cruised the dial. I felt like I was using a tabletop receiver: for such a small transceiver, the encoder is on the large side, and the controls are ergonomically designed. The spectrum display and waterfall are amazingly useful.
The front-facing speaker on the IC-705 is well-designed for audio clarity on the ham radio bands. It’s not a high-fidelity speaker, but it’s adequate and has enough “punch” to perform well in the field. Speakers on portable QRP radios are typically an afterthought and are terribly compromised due to space constraints within the chassis. The IC-705’s speaker design feels more deliberate, akin to what you might find on a mobile VHF/UHF rig. Broadcast listeners, in other words, will certainly want to hook the IC-705 up to an external speaker––or, better yet, use headphones––for weak-signal work.
While the received audio isn’t on par with a receiver like the Drake R8B, it’s pretty darn good for a portable general coverage transceiver. The audio is what I would call “flat,” but you are able to adjust the received audio in EQ settings to adjust them to your taste. Audio is well-tailored for the human voice, so I’ve found weak signal IDs are actually easy to grab on the air.
Audio samples
One of the brilliant things about the IC-705 is the fact that it has a built-in digital recorder. Both transmitted and received audio can be recorded in real time and saved to a removable MicroSD card. I made audio recordings of two broadcast stations on the 31-meter band as samples: the Voice of Greece (9420 kHz) and RadioExterior de España (9690 kHz). The Voice of Greece was moderately strong when I made the recording and Radio Exterior was quite strong. Click on the links to download the .mp3 files for each recording:
Voice of Greece
Radio Exterior de España
I’ve also used the built-in digital recorder to record long sessions of my favorite shortwave, AM, and FM stations. Even with the recorder on, I can typically achieve hours of listening on one battery charge and need no other power supply.
In short? The IC-705 makes for an excellent portable shortwave, mediumwave, and FM broadcast band-recording receiver.
Charging ahead…
The supplied BP-272 battery pack snaps snugly on the back of the IC-705
Power supply is always a concern when taking a transceiver on travels. Most transceivers need a 12-13.8 volt external supply, or an external battery, one that will eventually need to be charged.
This is not the case with the IC-705, because while it can be charged or powered via a 12-13.8V source, it can also be charged via a common 5V USB power supply. Simply insert any USB phone-charging cable into the MicroUSB port on the side of the IC-705, and it will charge the fully-depleted attached BP-272 battery pack in just over four hours.
Indeed, I traveled to visit family one week, and had plotted two park activations both en route and on the way back home. After my first activation, I quickly realized I forgot the supplied IC-705 power cord that I’d normally use to hook the IC-705 up to one of my LiFePo batteries. I was quite disappointed, expecting that I’d missed this opportunity. Then I remembered USB charging: I simply plugged the IC-705 up to my father’s phone charger, and in four hours, the battery was completely recharged.
To my knowledge, there are no other transceivers that have this capability without modification. A major plus for those of us who love to travel lightly!
Summary
POTA activation at the Zebulon Vance Historic Birthplace
Every radio has its pros and cons. When I begin a review of a radio, I take notes from the very beginning so that I don’t forget my initial impressions. Here’s the list I formed over the time I’ve spent evaluating the Icom IC-705.
Pros:
Frequency range
TX: 160 – 6 meters, 2M, 70cm
RX: 0.030-470.000 MHz
Modes include SSB, CW, AM, FM, DV, RTTY
4.3 inch color touchscreen that’s (surprisingly) readable in full sunlight
Multiple means to power/charge:
Icom BP-272 battery pack (supplied) for 5 watts output
Can be charged via 12V power supply or
5V USB phone charger with standard MicroUSB plug (admittedly, I wish they would have adopted now standard USB-C rather than MicroUSB)
Angled speaker/mic connectors can be challenging to insert as they are too close to the recessed area behind front face, especially for those with larger fingers and/or if in chilly conditions in the field
MicroSD card also difficult to access––I use needle-nose pliers to remove and insert
Conclusion
POTA activation of Second Creek Game Land
I purchased the Icom IC-705 with the idea that I would review it and then sell it shortly thereafter. Much to the dismay of my (rather limited) radio funds, I find that I now want to keep the IC-705…indefinitely.
I didn’t think the IC-705 would fit into my QRP field radio “arsenal” very well because I tend to gravitate toward more compact radios that I can easily operate on a clipboard on my lap when necessary. My Elecraft KX2 (TSM November 2016), Elecraft KX1, LnR Precision LD-11 (TSM October 2016), and Mountain Topper MTR-3B probably best represent my field radio interests.
But I’m loving the versatility and overall performance of the IC-705. It’s providing an opportunity to do much more than most of my QRP radios allow.
Here are just a few of the things I’ve done with the IC-705 thus far:
Activated numerous parks in SSB and CW
Connected to a local D-Star repeater and talked with a fellow ‘705 owner in the UK
Listened to ATC traffic (and recorded it)
Listened to NOAA weather radio
Listened to and recorded local FM stations
Enjoyed proper FM DXing
Recorded GPS coordinates during a POTA/WWFF activation
Made numerous digital mode contacts by connecting the IC-705 directly to my Windows tablet
Made a 2-meter SSB contact
POTA activation of the Blue Ridge Parkway
Indeed, there are more features on this transceiver than I can fully cover in one review; truly, I consider that a very good thing.
So if you’re looking for a portable transceiver that can truly take you on a deep dive into the world of QRP HF, VHF, UHF, and even satisfy the SWL in you, look no further than the Icom IC-705.
Well played, Icom.
More Icom IC-705 articles, information, and resources:
The Mission RGO One transceiver is one model being evaluated for a review in The Spectrum Monitor.
Many thanks to SWLing Post contributor, Pete, who writes:
Thomas, I’m curious what radios you have in the shack now. I see lots of posts about various radios, but I wonder what’s in your personal collection and what’s being evaluated. You know what they say…”inquiring minds” and all that! If you don’t mind I for one would love to see even a basic list of your rigs.
Thanks for your question, Pete. Your’re right–I don’t really have an inventory listed here on the SWLing Post. In truth, my radio collection is pretty dynamic–radios come in and go out a lot due to testing, evaluations and reviews.
Here’s what’s in the shack at present. I’ll start with ones currently in my personal collection:
There are too many to list! (Ha ha!) In general, I keep any portable radio I believe represents the best in its price class. I rotate using and travelling with each radio as best I can, but honestly keep them in the shack for any new reviews as I’m always in need of comparison radios. Here are some of the portables I believe I reach for most often (in no particular order):
Tecsun S-8800
Tecsun PL-880
Tecsun PL-660/PL-680
Tecsun PL-310ET
C.Crane CC Skywave
C.Crane CC Skywave SSB
Eton E1
Panasonic RF-2200
GE 7-2990
I also have a number of Handie Talkies, vintage solid-state portables, mobile radios and kit/homebrew radios and accessories like many radio enthusiasts.
This may seem like a lot of radios, but I have friends with collections that outnumber mine by orders of magnitude. In truth, if I didn’t evaluate and review radios, I’d have a much, much smaller collection because there’d be no need to keep reference radios on hand. I rely on comp models, however, to accurately gauge a radios performance when matched against a similar or “benchmark” model.
The following is a machine translation of the announcement:
“Thank you very much for your patronage of ICOM products.
We have received reservations from a large number of customers about the IC-705, a 10W walkie-talkie with HF~430MHz all-mode, which was scheduled to be released in late March 2020. Some of the parts involved in the production of the product are delayed due to the new coronavirus issue, and production has been delayed due to this.
We apologize for any inconvenience caused to all of you who are looking forward to our products.
As for the delivery of the product, because it is a situation in which the arrival schedule of the part does not stand now, I will guide it separately as soon as it turns out.
We will take a while to deliver it, but we will do our best to deliver it as soon as possible, so please understand us.”
Thanks for sharing this, Paul. No doubt, delays are due to the affects of Covid-19 on both manufacturing in Japan and throughout the IC-705 supply chain.
If you’re a member of the Radio Society of Great Britain (RSGB) you may have seen my review of the ALT-512 QRP transceiver in the March 2020 issue of Radcom. This was my first review for Radcom after having been invited to submit a review at the 2018 Hamvention.
I love Radcom so was pretty chuffed to see my review in the March pages:
I had the ALT-512 here at SWLing Post HQ, on loan from the manufacturer, for the better part of six months. I got to know this little radio inside-out. I’ve operated it in the field, in the shack and covered ever mode including FT-8 contacts during portable operations and even in a high school classroom.
Operating FT-8 with my ham radio class high school students last year. The ALT-512 is a digi-mode champ. With a very modest indoor mag loop antenna we averaged about 110 miles per watt.
The ALT-512 is a versatile, sturdy little rig–designed and manufactured in Bulgaria. I really only had minor complaints about this transceiver. I saw a bright future for this little rig. It was well-designed and backed by a company and team of ham radio operators that had already successfully launched several other transceivers.
Then the unexpected happened…
Early last month, I learned that the ALT-512’s main engineer and designer, Dobri Hristov (LZ2TU), passed away.
If you own the Sky SDR or LD-11, you may have communicated with Dobri at some point when you needed technical support. Dobri was a well-respected fellow and distinguished ham radio operator/DXer. I corresponded with him quite a few times in the past.
Sadly, when Dobri passed away, he took the ALT-512 with him.
I think the ALT-512 would have been very successful and competitive in the European market and beyond.
Dobri passed away as the March 2020 issue of Radcom was being printed. He never got to see it, but I’d like to think he would have been quite proud of his little transceiver. In the end, I think it was an overall positive review.
If you’re into ham radio and are looking for a top-shelf publication, consider joining the RSGB and subscribing to Radcom. I highly recommend them even though their judgement was obviously impaired when they invited me to write a review–! 🙂
The following review first appeared in the February 2020 issue of The Spectrum Monitor magazine.
A Tale of Two Radios: CommRadio CTX-10 v Elecraft KX2
As my blog readers often point out: Why focus on low-power (QRP) ham radio activities when propagation is so dismal…even for high power stations? A logical argument, I’ll admit, and lately it’s become a common theme in QRP discussion.
But I’ve said it before, and I’ll say it again: despite the current stagnation of the sunspot cycle, we’ve been seeing a very curious uptick in low-power radio innovation. Manufacturers have been churning out QRP transceivers at a rapid rate during this solar lull, and I can assure you, it’s a strategic move that the marketplace rewards.
So, why should this be? I attribute the influx of QRP radios to several factors.
First of all, leveraging innovations in SDR (software defined radio) design, it’s simply become less expensive to produce portable low-power radios with extra features. In other words, manufacturers can now offer more radio bang-for-buck. Similarly, the technology is accessible enough that even smaller manufacturers can produce competitive products.
Secondly, the new-found popularity of field activities––such as Parks On The Air (POTA) and Summits On The Air (SOTA)––fuel the need for field-portable, all-in-one transceivers. Anyone who falls in love with field portable operation, and it’s easy to do, will quickly discover how handy it is to have a dedicated radio for these activities.
However, it’s not always competition that pulls radio operators to the field. With so much QRM (human-generated interference) at home or in built-up areas, many operators and radio enthusiasts now take to the field to escape the noise. Likewise, many operators live in restricted communities that don’t allow for permanent antennas, so it’s in their best interest to make their radio shack…well, portable.
And why not? Weak-signal digital modes like FT-8 have made signal-hopping across the planet with only a few watts of power easier than ever before. I’ve spoken with a number of operators who have––using FT-8––worked DXCC for the first time with stealthy, portable antenna systems, and others who have taken the dare to work DXCC only on individual bands. Such challenges are all in the name of fun.
Finally, in general, QRP transceivers are much less expensive than their 100 watt counterparts. QRP radios gain a competitive edge by omitting pricey amplification in the design, while still offering the operator DX-class features and receiver performance.
Making a choice
With so many new field-portable QRP transceivers on the market, making a choice can be difficult. Still, there are some guidelines that will help you eliminate a number of models.
The Mountain Topper MTR5B
For example, if you only plan to operate CW and don’t need a general coverage transceiver, you can effectively eliminate all of the priciest QRP transceivers. CW-only transceivers like the popular Mountain Topper series are incredibly portable, durable, and half the price of full-featured multi-mode transceivers.
Also, if you use resonant antennas, there may be no need for an internal or external antenna tuner––this can save you upwards of $200. If you prefer using an external battery, there may be no need to purchase a model with an internal battery option.
In this article, however, we’ll be looking specifically at two general coverage QRP transceivers that are very much all-in-one. With an antenna, mic and/or key, these radios will get you on the air in a matter of seconds.
Our competitors
Over the past year, I’ve received numerous emails and comments asking for advice choosing between two specific radios: the recently reviewed CommRadio CTX-10 and the Elecraft KX2.
I’m not surprised, because both of these field-portable QRP transceivers sport similar basic features and options, e.g.:
Ham band coverage from 80 – 10 meters
General coverage receiver
Internal batteries
Built-in ATU
Small and lightweight
Designed and built in the USA
Although the CTX-10 and KX2 share the same goal of functioning as an all-in-one, grab-and-go field radio, I believe they have very different appeal.
Herein lies the key to choosing the right rig for you, and the point I hope to prove in this article: it’s based on your personal operation philosophy.
The Elecraft KX2 is the “Swiss army knife” transceiver. It has an amazing array of capabilities, features, and adjustments, yet is incredibly compact and could easily fit in your jacket pocket. Moreover, the KX2 is backed by Elecraft, one of the most successful amateur radio manufacturers in business.
The CommRadio CTX-10, on the other hand, was designed with a basic feature set in mind, dead-simple operation, and near mil-spec quality inside. The CTX-10 is the transceiver iteration of the popular CR-1 series receiver by CommRadio.
When I’m asked which radio is best, I respond with a series of questions––because I first need to discover what type of operator the potential user is, to give him/her a good recommendation. Below, I’ll break down some of the key questions to help guide you in making a decision between these two transceivers. Note that these questions are ones that should be asked when purchasing pretty much any transceiver.
Do you plan to engage in more ham radio operation, or broadcast listening?
True, since the CTX-10 and KX2 are both general coverage transceivers, either radio can serve. But if you’re primarily looking for a broadcast listening radio and you might only occasionally hop on the bands to make casual ham radio contacts, then you should give the CTX-10 some consideration.
The CTX-10 is essentially a transceiver version of the excellent CR-1a receiver. It is better equipped for listening to broadcasts than the KX2 because it has three AM filter settings: 5, 7.5, and 15 kHz. In contrast, the KX2 AM filter can only be widened to about 5 kHz. CTX-10 AM audio fidelity is superior to that of the Elecraft KX2.
In addition, the CTX-10’s receiver coverage dips down to 150 kHz and it’s quite capable on the mediumwave band. The KX2’s receiver covers 3 MHz – 32 MHz and 0.5 – 3 MHz with “reduced sensitivity.” In other words, the KX2s receiver architecture is designed for the ham bands, thus mediumwave sensitivity is suppressed on purpose. I’ve certainly listened to mediumwave stations on the KX2, but only to local, strong stations. You could never hop into mediumwave DXing on the KX2 like you can on the CTX-10.
With that said, if you’re primarily looking for a ham radio transceiver for operations in the field, and you might only occasionally do shortwave radio listening, then you should give the KX2 serious consideration. In my opinion, the KX2 is simply a more capable, adaptable ham radio transceiver than the CTX-10. (More details on this point to come.)
The Elecraft KX2 doing a little coastal SWLing.
Now, here’s the irony: Although I had a CTX-10 in my shack for almost a year, I still defaulted to taking the KX2 on trips when I thought SWLing might be my primary activity. Why? The KX2 has a very robust and capable HF receiver. Its only real limitations are a lack of wide AM bandwidths and sub-3 MHz frequency coverage and performance. I find that the KX2’s 5 kHz AM filter sounds pretty good, though; when using headphones, the KX2’s simulated stereo audio effect really makes the audio sound broad and pleasant. I also rarely use ham radio transceivers to do mediumwave or longwave DXing––I use dedicated portables like my Panasonic RF-2200, or an SDR––so mediumwave and longwave reception is never a serious limitation for me.
But, again, if you primarily plan to do broadcast listening, the CTX-10 is the stronger of the two choices.
Are you looking for a feature-packed radio that can be tweaked and adjusted on a granular level?
If so, you’ll definitely want to choose the KX2 over the CTX-10. The CTX-10 has an incredibly basic feature set, while the KX2, like most Elecraft radios, has an abundance of features, functions, and adjustments at your disposal.
If you want a simple, unfussy radio that automatically adjusts most user controls like microphone gain and compression, then the CTX-10 will suit you fine. If you like both automatic and manual control of your radio’s settings, the Elecraft KX2 is your rig.
How important is internal battery operation and ease of recharging?
The CTX-10 has best-in-class internal battery capacity and intelligent charging. You can literally play radio for hours on end without depleting the batteries in the CTX-10. The internal batteries can be charged via the DC power port, or even via USB cable.
The KX2 Battery
The KX2 uses an internal battery pack that must be removed each time to charge. I’ve taken the KX2 to the field more than 100 individual times and find that I can operate at full power for about one hour fifteen minutes (with a heavy amount of transmitting) before the voltage drops, and the output power, as well from about 10 watts to 5 watts. Of course, when in receive, it’ll operate for hours without recharging.
Of course, with a swappable battery pack, you can bring additional pre-charged batteries to the field to eliminate the need to recharge.
I’ve never found recharging or swapping KX2 batteries to be a problem, but internal battery operation via the CTX-10 is certainly its strong suit.
One known issue with some of the CTX-10 units: when charging the internal Li-Ion cells, my initial 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. It was quite annoying because I can still hear frequencies in that range. The second evaluation unit didn’t have this problem. If your CTX-10 has this problem, contact CommRadio for help.
Are you primarily a CW operator?
If you are a CW enthusiast, chances are great that you’ll prefer the KX2 over the CTX-10.
The CTX-10 has very few settings for CW mode. In fact, it doesn’t even (presently) have a side tone control or support iambic operation. The CTX-10 uses a traditional relay for TX/RX switching, but you can’t presently change the hang/delay time. The CTX-10 cannot do full break-in QSK.
Elecraft transceivers are designed by CW operators and sport true benchmark CW performance. The KX2 allows granular control, thus can be tailored to accommodate any operator. The KX2 has silky-smooth full break-in QSK. If you’re a CW operator, you’ll much prefer the KX2.
Are you primarily a digital mode operator?
The CTX-10 body (left) is essentially a large heat sink.
If so, you’ll want to consider the CTX-10, because it can run high-duty cycle modes like FT-8 in the field without ever overheating. This is also one of the CTX-10’s strongest points.
Both the Elecraft KX2 and KX3 will decrease power output after running FT-8, for an extended period of time, to protect the finals from overheating. Operation time can be significantly extended by adding an optional third-party heat sink. The CTX-10 does not have this issue, however, as the CTX-10 body itself is essentially a heat sink. In all of my testing, I never came anywhere close to overheating it.
Are you primarily an SSB/phone operator?
If SSB is your game, you’ll prefer the KX2.
The CTX-10 essentially has no microphone controls––in fact, it doesn’t even have an adjustable mic gain. The microphone input is completely auto-controlled by the CTX-10, via a limiting pre-amplifier, built-in compressor, and ambient noise gate. The only ways you can really affect how audio is transmitted, in fact, is by changing the distance from your mouth to the mic, and/or changing how loudly you speak into the mic.
If you have a favorite boom headset (like Inrad or Heil), note that it may not work well with the CTX-10, simply because you have no control of the mic inputs.
The KX2, on the other hand, has robust microphone controls; you can, for example, even change the EQ settings of your transmitted audio.
How important to you is the capability of your rig’s internal ATU?
The CTX-10 sports a nifty internal antenna tuner, but it doesn’t match the performance of the KX2’s internal ATU option. In my field work, I found that I needed antennas that were pretty close to resonant for the CTX-10 to match them. The ATU was certainly a handy feature on the CTX-10, but it didn’t allow me the flexibility to, for example, load up a random wire antenna.
Update (23 Mar 2020): Brian Haren informs us that with firmware update 1334 issued by CommRadio on December 18, 2019 “performance of the internal tuner was vastly improved.” This firmware was issued after my review unit was sent back to CommRadio.
The KX2’s internal ATU, on the other hand, is benchmark, and can tune via nearly any antenna––indeed, it would almost tune a metal chair, if you tried to load it. It’s as good at matching antennas as my Emtech ZM-2 balanced line tuner. In fact, I once loaded a 20-meter hex beam on 40 meters with the KX2 in order to work a rare park activation. No other radio in my arsenal could match that (well, frankly, it was asking a lot), but the KX2 not only matched the antenna, but it got an excellent match: if memory serves, something like 2:1. (And, yes, I worked my park!)
Note that the ATU comes with the CTX-10 package, while the KX2 internal antenna tuner is a worthwhile $200 option.
Are you on a budget?
Everything included in the CTX-10 box.
When you purchase the CommRadio CTX-10 for $999.99, you’re buying an all-in-one package: a transceiver, internal batteries, and an internal ATU. There are no other options to purchase separately. The CTX-10 doesn’t ship with a microphone, but it does include a USB cable, DC power cord, and CD manual. You simply unbox your CTX-10, make sure it’s been charged, plug in your microphone (requires a modular plug type like the Yaesu MH-31A8J or MFJ-290MY) or key, add your antenna, and boom! You’re ready to hit the air.
Unlike CommRadio, Elecraft started as a kit manufacturer. Their philosophy has always been one of purchasing a basic unit, then adding features when you’re ready. In a sense, this gives the customer a lower starting price point. Here’s how the KX2 pricing breaks down:
Elecraft KX2 transceiver: $789.95
KXAT2-F internal ATU option: $199.95
KXBT2 Internal Lithium Battery option: $59.95
KXBC2 Lithium battery fast charger: $29.95
KXIO2 Real-Time clock: $79.95
To configure the KX2 to be equivalent to the CTX-10––meaning, with ATU, internal battery, and charger––your total price would be $1,079.80. This is the configuration of my KX2.
If you use just an external battery and resonant antennas, the base KX2 might be the only radio you’ll ever need. At $789.95, that’s $210 less than the CommRadio CTX-10. Fully configured, however, the CTX-10 is about $80 less expensive than the KX2.
Apples to oranges, in radio terms
If you haven’t gathered already, although both the CTX-10 and KX2 are general coverage QRP transceivers, they are completely different––like comparing apples to oranges––in terms of the market they wish to reach.
No doubt, CommRadio designed the CTX-10 to appeal to people who love commercial or military channelized radios. Based on my interaction with CTX-10 owners, many are into preparedness and primarily infrequent simplex SSB operations.
The KX2 will appeal to hams who are active operators and who enjoy full control of their radio’s functions and features. Elecraft has a massive and loyal community of users and fans.
Summary
If I haven’t made it clear yet, there’s much more involved in making a purchase decision than simply looking at the specifications of a radio. Often, it’s a truly personal and subjective choice.
Be honest with yourself about your needs, and base your purchasing decision on those. After all, in this case we’re talking about two capable radio transceivers, either of which should provide years of great operation and listening.
Last Friday, after returning from holiday travel, I found a belated Christmas gift on my doorstep: the new uBITX V6 QRP transceiver.
In the spirit of full disclosure, this package wasn’t delivered by Santa, rather by DHL in record time from India. As I mentioned in a previous post, I simply couldn’t resist purchasing such an affordable general coverage transceiver.
To be clear, the uBITX V6 isn’t really a kit. The boards are all fully populated by a women’s cooperative in India. You can purchase the uBITX V6 for $149 without a chassis and for $199 with a custom metal chassis. I purchased the latter.
Assembly may take thirty to forty minutes following HF Signals’ online guide. I employed my twelve year old daughters who pretty much assembled the entire radio–I only helped seat the display to the main board.
There is no firmware or software to upload. Simply assemble the radio, solder a power cord to the supplied coaxial plug (hint: positive tip polarity), connect an antenna, connect a power supply, and turn it on.
You’re on the air!
So far, I’ve only scanned the bands and listened to QSOs and broadcasters (no AM mode, so I’ve been zero-beating stations in SSB). Today, I hope to chase a few parks via the Parks On The Air program.
I still need to calibrate the radio yet (although it does zero beat WWV perfectly).
If you purchase the uBITX V6, don’t expect a benchmark transceiver. This uBITX V6 feels more like a work-in-progress and I assume the pre-loaded firmware is simply a first iteration.
Since the radio is open source, I expect hams will soon hack this rig to go above and beyond its basic (understatement alert–!) feature set.
If you’re a CW operator, you might hold off on purchasing until someone has properly implemented the mode. I made some test CW CQs into a dummy load just to check out the keyer and I honestly don’t think I could manage a proper QSO at this point. Sending is sluggish and…well…awkward.
Note that I will be writing a full review of the uBITX V6 for a future issue of Radcom (the RSGB’s monthly publication). Check back here for uBITX V6 notes along the way.
Also check out the excellent blog of our friend, John Harper (AE5X), who has also recently put the uBITX V6 on the air!
Many thanks to SWLing Post contributor, Dave Zantow, who notes that Reuter Elektronik recently introduced their latest radio: the RDR52 QRP Transceiver.
