CommRadio CTX-10: Tiny Radio, Huge Capability

When I first started in this whole off-grid and guerrilla communications stuff, I was looking for civilian side solutions to some of the same equipment I had when I was in the Army. Without a doubt one of the coolest radios I had a chance to play with was the Harris PRC-150, a 20 watt HF unit that houses quite a bit of capability into one package. The ability to have a tuner and data terminal all built into one rig to communicate possibly globally seemed like the solution to quite a bit- operating long term and long range, working with it just in training inspired me to get into amateur radio.

Harris PRC-150 HF radio. Credit: Harris Corporation

Since getting a PRC-150 is impossible (you can find its older brother, a neutered PRC-138, if you have an extra $4000 laying around and someone at Harris to repair the inevitable faults), I started looking at off-the-shelf solutions. That lead to amateur radio. The closest thing that what I was looking for at the time was the Icom 703. But the soldier in me said squeeze the most versatility out of a piece of equipment you can- which after some browsing around lead me to the Yaesu 817. For a long time it’s been the gold standard in versatility. An all mode radio that covers almost every band in the spectrum while consuming a relatively small amount of power has served the QRP (low power radio) crowd well and likely will continue to do so for a long time. And although I’ve used it for many years despite newer products coming on the market, it’s got some serious drawbacks. The exposed wires running to the tuner and the data interface can be points of failure at worst, extra gear to carry at best. It puts out a meager 5 watts, which is fine during the peaks of the solar cycle but in the approaching minimum, it’s far less than ideal on HF. But the biggest thing is that it is a technological product of its era; designed in 2004, it hasn’t changed much in 14 years.

Elecraft came along and built not one but two modern rigs for the market- the highly successful KX3 and its smaller brother, the KX2. It’s a software defined radio, meaning that the firmware itself can be upgraded as time goes on, improving the performance of the radio in various ways. SDRs are also usually better receivers than earlier rigs, and Elecraft is certainly no slouch. While both are considered Cadillac tier equipment, they’re anything but rugged, requiring multiple hardware upgrades out of the box. One thing that’s absolutely necessary for high duty cycle transmitting is an add-on heat sync to disperse heat build up in the body of the radio. And being top tier carries a top tier price tag. Even the smaller KX2 when equipped with internal battery and tuner costs just shy of $1200, making it an expensive, delicate radio to be carrying in the bush.

So naturally I got very excited when CommRadio, the maker of the now discontinued CR-1 receiver, announced the CTX-10. It represented everything I had looked for in a civilian side radio- an all components in one, lightweight and durable little rig pushing out 10 watts. Internal power, internal soundcard, internal tuner- everything I need in a grab and go HF package. So after following its lengthy development I reached out to the design team for a possible evaluation. Not only were they receptive to the idea, but a member of the team told me he wanted to build “the prepper’s radio”. Generously supplying one of the test models to be used in the last several classes I’ve run, the following is a three month review of this rig in its intended environment- (mostly) grid down, using improvised antennas, and running every mode from single side band phone to digital and even some shortwave listening.

Technical and Functional

The radio receives 150kHz-30mHz, and transmits on the amateur bands of 80m-10m. It is a true SDR, having an excellent receiver and a very simple layout for controls. There are not any complicated menus, being even simpler than my Icom 7200 to operate. Finding a frequency is as simple as using the arrow buttons and turning the main tuning knob. The operator can rapidly skip through the various bands using the band button and change the operating modes via the mode button. I have not seen a radio with a layout this simple; the Icom 706 series came close and the 7200 does also, but this rig by far has the shallowest learning curve to getting on the air.

Tuning is a simple affair also- press in on the volume button (hold it to power on/off) and the radio begins a tuning cycle. While it does not have the range of larger external tuners such as the ones made by LDG, meaning it won’t tune an antenna cut for 20m to an 80m frequency. You wouldn’t want to do that anyway using a QRP (or really, any) radio- it’s incredibly inefficient, and as all QRP operators know, building an efficient antenna is a large part of making successful contact. For a built in antenna tuner of this size, it’s excellent, and had zero issues matching my 40/80m NVIS dipole to both bands. As the photo shows, it made a perfect 1:1 match in under a second, where the LDG tuners I use with the Yaesu 857 and Icom 7200 take a bit more time on that same antenna.

The radio includes three internal 18650 lithium ion batteries that are chargeable via the included cable. Any wall wart or USB outlet can charge this radio, lending a great deal to its versatility data points. It can operate from a wide variety of voltages- ranging from 10-20V of DC current. The batteries themselves last a long time in this rig- its advertised claim of 28 hours listening on full charge is accurate. In fact, aside from the initial charge, the radio kept an operating charge on the batteries across two weeks of intermittent use ranging from listening to shortwave to testing the features and demonstrating its capabilities in class through making contacts. It can truly operate a long time off grid, unlike the FT-817’s internal batteries which in my experience are a waste of time and space.

Other features of this rig really demonstrate the thought towards versatility the designers put in. All attachment points are on the rear of the rig, including standard speaker and CW (morse code) key plugs, Yaesu microphone jack, and a standard data jack found on Yaesu radios as well as a USB jack for firmware updates and to pull data being received by the radio over the air.

The radio interfaces well with my ancient android device running AndFLMsg, which is FLDigi ported to mobile devices. You can download it from the sidebar on the Brushbeater site. The entire package, radio and phone, is incredibly small and lightweight, offering a simple and rugged off the shelf solution for running digital modes in the field.

Speaking of using it in the field, the radio is easily the most rugged amateur radio built today and possibly ever. The body is one large heat sink to withstand a high duty cycle which is needed when operating many digital modes, most notably FT8. The knobs on the rig, usually made of plastic on other radios, are made of solid aluminum and have a genuine feeling of quality. This is a radio built to last under more austere conditions than easily any other in its price range.

But How Does It Perform?

The CTX-10 fits perfectly in a Harbor Freight Apache 1800 case, roughly the same size as a Pelican 1150. The whole package is light and tight.

Testing it against a Bird watt meter, the radio puts out a full 10w at full battery charge. The power output is selectable in three levels- 1, 5 and 10 watts. It puts out those levels exactly as advertised. In the field, its small size and versatility makes it very handy. For me one of the most important factors in a radio is the amount of space it takes up in a rucksack; this radio is not only small but requires little else to be ready out of the box. Inside its small waterproof box, it can fit in any assault pack with lots of room left over for all the other gear I’ll need on a long range patrol or the insertion into an area of operations.

Across three RTO Courses and an Small Unit course, many got hands on with the radio in its intended environment. Operating head to head against an Elecraft KX3 in the first, we found it to be just as simple in interface in a slightly smaller, simpler and less expensive package. The receiver quality was noted in the second and third courses, both while being used during class and while students were getting hands on after the formal instruction. At one point a contact was made from the class location in NC to another in PA using sideband voice (commonly called ‘phone’) while the noise floor was especially high- I didn’t expect him to get through, but he did. While not a complete testament to the radio alone, the fact that the signals on both ends were heard so well definitely ensures confidence in good equipment.

The last bit of functionality that needs pointing out is the built in morse code reader. It’s an excellent feature that actually does work unlike other code readers on the market. Its a very valuable tool if you’re learning code, are hard of hearing, or for whatever reason just like reading what comes over the air. It may not be the first feature people buy this radio for, but its one of those hidden benefits that I happen to like.

My Final Thoughts

As I stated in the beginning, my search for an all in one solution has went on for a long while- by the looks of things and the comments from people I have in class, I’m not the only one. This radio represents a big leap forward both in technology but in capability. Doing everything I think a low power / field HF radio should, this small radio should be at the top of any prepper’s list looking to build their capabilities. It’s as close an answer as I think civilians can get to the questions I wanted answered when I first got into small unit communications outside of the Army. While I don’t think it should be your only radio- that should be a 100w rig- it definitely has a place in that vehicle kit or ham radio bugout bag. While the price is not cheap (right at $1,000 as of this writing), it is cheaper than its nearest competitor, the KX2 when similarly outfitted, and on par with the cost of a Yaesu 817 by the time you buy a tuner, sound card and cables. For me, its definitely worth it and I’m buying the test model I was sent. On top of that, it’s an American product by an American owned company. They set out to not build a QRP radio but build the best QRP radio, and I think they did.

We’ve got class dates lining up for next year. Good gear can only supplement solid training.