Updates on CommRadio’s CTX-10

CTX-10.jpgThe CommRadio CTX-10 has got myself and many other QRP enthusiasts excited- and for good reason- it’s built from the ground up for field use meaning it’s not only rugged but it packs everything you need in one box for HF. As you can see in the photo above, it’s tiny, pushes out 10w, and has a heck of a lot of capability in one small package.

The team behind it has kindly forwarded a preliminary copy of the manual for you to look over- there’s a lot to get excited over.

CTX-10 User’s Manual – Preliminary Released – 5 APR 2018

A couple more photos to sink in the size:

Coors Banquet + CTX-10 RLM_8211.jpg

5x7 CTX-10 and Cards - for printing - RLM_8209

38 thoughts on “Updates on CommRadio’s CTX-10

  1. Brian

    Either the Aussies are selling beer in 12 inch high tins or that is a neat little radio – I am happy with either answer ! Do you now if this has a CAT control function ? Good to see someone just ‘having a go’ and manufacturing a new product. We are all for diverse supply chain options.

  2. LodeRunner

    Manuals are nice. Actual evaluations by experienced operators such as your self are priceless. Waiting with baited breath for the latter…

      1. LodeRunner

        Agreed, and amen. Also, the uBitX I ordered is in hand; it needs to be wired up and given a shakedown cruise. I’ll probably get it wired and operating “open air” style, this weekend – I won’t put it in an “ammo can” until I know it’s Field-Ready ;P

        I know you’ve got a full plate right now, but the offer still stands to give you some time with it when that works for you, just let me know.

  3. Henry B


    Thanks for info.

    looks great so far..

    Great HF band coverage, many rigs like this do not offer all these bands…

    160m would be nice..

    My speculation on first blush is this:

    By using the 2.5mm pin x 5mm barrel, pin positive (+) power
    receptacle one can buy these usb cables https://www.amazon.com/Onite-5-5×2-1mm-5-5×2-5mm-Electronic-Organorgan/dp/B076Q8WNCH?psc=1&SubscriptionId=AKIAILSHYYTFIVPWUY6Q&tag=duckduckgo-ffab-20&linkCode=xm2&camp=2025&creative=165953&creativeASIN=B076Q8WNCH

    and this solar panel SunJack 20W Solar Charger + 2x10000mAh QC 3.0 Power Banks – Portable Solar Panel with USB and have the ability to recharge the built in Three (3) Tenergy model 3000
    6, type 18650 cylindrical Li-Ion cells, or use the power banks w solar panel.


    add in an ldg z-100+ auto tuner that can be run off a 9v battery, and one has the makings of a very nice HF emcomm kit, stick in a pelican case and life is good.

    Add a multi band dipole or fixed/random spider wire antennas and you got comms…..

    Looking forward to your hands on analysis…

    1. LodeRunner

      Manual says there’s a built-in auto-tuner (L-Network) which is impressive for a rig this size… although the notation about having -only- 6 x 7 tuning settings suggests a limited matching range.

  4. Bob Martin

    Henry B – The CTX-10 already has an automatic antenna tuner built-in, so perhaps you won’t need the z-100+?

  5. Henry B

    Bob et al;

    A wise Senior NCO who was/is squared away RTO, once opined that relying on the internal tuner to tune and more importantly protect your radio was not wise.

    I splained to him that my rig had an internal tuner, a kenwood ts440, but lo and behold, could not get it to actually match/tune up antennas all the time, especially random long wire…

    so, he suggested that one is none, two is one, and that i might be better off w the z-100+, because it can tune a playground set, barbwire fence if need be. ๐Ÿ™‚

    Yup, for approx 150.00 and 9v battery, he was right.

    I know the z-100+ works, very well, and more importantly, it actually acts a stop gap to protect the rig from electrical/rf issues that the internal tuner may not do, where the z-100+ will do it.

    so, if i am gonna drop some cash on a decent qrp mobile hf rig, i want to be able to both tune up various antennas, and provide protection and the z-100+ does both, at a very affordable price.

    Think insurance for your rig is all.



    1. Something tells me the technology in this tuner and the one in that 440 is gonna be a bit different. ๐Ÿ™‚

      That said, never hurts to have a spare unit. It’s like an insurance policy. Then again, with QRP, we want antennas as close to resonance as possible.

  6. Henry B

    So, does that mean that you’d use the internal tuner over the external or use external and have internal as back up?

    would not either tuner match up resonance sufficiently?

      1. Badger

        Very interesting piece of gear. Thanks for sharing & leveraging a peek at the manual. Couple thoughts/questions.

        Without seeing rear-panel (including a pic of that view in the manual is normal) can’t tell but folks who have traditional pig-tails sitting around for power supplies may want to make sure they are paying attention to polarity, with this connector at center-POSITIVE.

        RE external tuners: Agree, certainly make the antenna as good as you can. If not, get thee an Elecraft T-1 running on its commonly found 9V transistor battery and fuhgedaboutit.

        Filtering (particularly CW): Anxiously awaiting your impressions of the rig itself. Having been spoiled before am truly curious how much of that typical “ringing” their CW filter has at 500Hz; the kind usually found on most any rig nowadays that has a digital implementation of a filter. Wish they’d go narrower than 500Hz; less makes it a bit easier to go up on someone’s band-edge far from the madding crowd & converse. Also, besides narrowing, what – if any – is the attenuation payload for that narrowing. That kind of stuff.

        Neat little package – thanks!

  7. Henry B


    one less piece of kit to hump, as ounces = pounds and pounds = pain….

    thank you….

  8. Pingback: Brushbeater: Updates on CommRadioโ€™s CTX-10 | Western Rifle Shooters Association

  9. Brian

    I am looking at this rig head to head with the also solidly built x5105.

    Comments above made me realise I dont know enough about autotuners at the technical level. Eg how you measure their range and how they reduce (?) the effectiveness of an untuned antenna. Candidate for future article ??

    1. It is. Really that’s a topic unto its own.

      The X5105, while it appears to be a solid radio by most sources, has a very limited range as far as auto-tuning goes (aside from the 5w max output vs. 10w for the CTX-10). Tuners match impedance mismatches (measured by your actual SWR) to make the radio “see” a 1:1 (versus the actual 2:1, 3:1, etc). The X5105’s internal tuner appears to only match at best a 3:1 antenna- meaning that if the antenna has a higher SWR than this, it won’t match it.

      KEEP IN MIND: You tuned SWR is NOT your actual SWR. The closer to resonance your antenna actually is (a topic covered in class) the more efficient it will be.

    2. LodeRunner

      measuring their “range” is a bit complex – there’s the “resistive” portion of an antennas impedance (which does the actual radiating of signals) and the “reactive part” which is a measure of how far “off resonance” the antenna is – but reactance dissipate no power, it reflects it. The reactance has to be “tuned out” to make the antenna “look resonant” to the radio, AND the resistive component has to be transformed to 50 ohms.

      With an L-Network, just two components (one inductance and one capacitance) have to do both of these functions – so the more of those resources are spent on tuning out the reactance, the less are left over for transforming the resistance, or vice versa.
      This is why NC Scout puts so much emphasis on resonant antennas – if your antenna is at least resonant somewhere on the band you’re operating on, then the tuner has less work to do, and will thus be more efficient.

      The last item to consider is “losses”. Losses tend to increase as current through a component (in our case the coil and capacitor of the L-Network) increase. Very low impedances mean very high currents will be involved, and losses will be high. Also, when your coil is would on a ferite core (which in every auto-tuner I’ve seen, they are), then high voltages can also cause higher losses.

      A 2:1 VSWR can be either a 25 ohm load, or a 100 ohm load. While they’re both “2:1” on the meter, there’s a 4 to 1 current differential (4 times more current for the 25 ohm load that the 100 ohm load). Any tuner will match either of these conditions, but losses will be ~4 times as high for the 25 ohm load. A 3:1 VSWR can be either 16.6 ohms or 150 ohms, a 9:1 current differential. The 150 ohms isn’t a problem, but the 16.6 ohm load definitely can be –

      Down below 20 ohms is where most portable tuners (auto- or otherwise) start to suffer very high losses due to excessive current in the coils. It’s safe to assume, at 20 ohms, that the loss in the tuner will likely be around 20% of your transmit power – or 1 watt of your 5 watt QRP signal lost in the tuner. At a load impedance of 10 ohms (5:1 VSWR) losses in the same tuner may well be 50% or more! Below 10 ohms is a “failure formula” – at least 75% and possibly 90% or more of your power is going to losses (heating up the components of your tuner), and bad things may well happen if you transmit for any period of time into such an arrangement – melted plastic, toroidal cores that no longer have the values they were designed for, and burnt up relays are all very possible outcomes.

      Above about 500 ohms load impedance is where things get ugly with the toroidal cores in the coils. Assume that when matching a 500 ohm load, the losses will be ~25%, and at 800 ohms the losses in the tuner may well be 75% or higher! Potential damage on this end of the range includes arcing across relay contacts (will cause relay burn-out, immediately or eventually) and “voltage puncture” of the dielectric in capacitors, which is “instant smoke” for the capacitor(s) in question, as well as “flux deformation” of the toroidal coils – their values will be permanently changed (at a minimum) and the cores could shatter if you are running the tuner near it’s full-rated power into such a load for very long.

      In both cases (very low and very high load impedance) I have stated the losses **just for the tuner**. There are lots more losses to be accounted for in the coax, because it is operating so far from it’s 50 ohm design impedance.

      For coaxial lines being operated in an un-matched condition (i.e. one or both ends are not seeing a “perfect” 50 ohm resistive load with no reactance, then the coax itself becomes a “transmission line transformer”… so the actual resistance and reactance at the antenna end of the line probably won’t be what your tuner sees at the input end of the line – the ONE exception is if your coax is an ELECTRICAL 1/2 wavelength long.

      When a run of coax is an electrical 1/2 wavelength long (or a multiple of this length) at the operating frequency, then the coax will “mirror” the impedance of the antenna end at the input end, faithfully. To calculate the proper length to cut the coax to, you have to know your desired frequency of operation, and the Velocity Factor (VF, typically specified as a two or three digit decimal figure – 1>VF>0) of the specific coax you’re cutting. Lets look at two examples, both on the same 40 Meter frequency –
      The formula is 492/Fr(mhz) * VF = length in FEET {{NOT 468/Fr(Mhz) which is the Dipole formula…don’t confuse the two}}
      492 / 7.10mhz = 69.296 feet.
      Now, lets say that you are using “Solid dielectric RG58” with a specified VF of 0.82, so you multiply 69.296 feet times 0.82 to get 56.823 Feet as your “cutting length”.

      With foam RG8X the most common VF is 0.66, so you multiply 69.296 feet X 0.66 to get a cutting length of 45.735 feet.
      Big difference between these two types of coax, when you look at it this way.

      If you cut your coax for the center of a particular band, then you can safely assume that you will get something *very near* the antenna impedance at the input of the line across that entire band (except 80 and 160 Meters), as opposed to playing Russian RF roulette with a “random length of coax.”

      I was told, about 30 years ago, that “you can’t go wrong with a half wave dipole fed with a half wave of coax”. That advice has stood the test of time exceptionally well. I’ve since learned why, and this is the explanation.

      Also, a 1/2 wavelength of coax cable for 40 meters is a full wavelength on 20 meters, so it will behave predictably there, as well – you might even get four bands “in line” this way if you plan ahead, i.e. 7.10/14.20/21.30/28.40Mhz.
      160M and 80M can work together too, i.e 1.85Mhz and 3.70Mhz, or 1.90Mhz and 3.80Mhz.

      So, it’s not just the antenna itself that you want at (or close to) resonance… whenever possible you want a resonant system – to maximize efficiency and minimize stresses in you radio and tuner.

      I could do a full 2-day class just on this material, but I’ve given you the short, short version.

      1. Brian

        Thanks LodeRunner for taking the time to try and drag my knowledge level up out of the dirt.

  10. Hypo

    Time to get back On the air and maybe upgrade to Extra.
    I have a 10 Watt LDG I used with a Uniden HR2510 on 10M ready to go.
    Doing Couch to 5k now
    Shooting Steel Challenge with my Shadow 2. 5k rounds since November and it is slick.
    3.5 Titegroup and a Ranier 124 RN.
    Tink Tink Tink Tink Tink

  11. Mike

    Look very cool
    And I agree comms is also very important.
    However what system with the most bang for your buck on the inexpensive would still do the job

    1. I’ve covered this topic many times over. If you want a HUGE leg up on this topic along with a serious amount of hands-on, consider taking one of my RTO Courses.

  12. We’re now settled on our mountain in Idaho and I can’t wait for our stuff to get here from the movers so I can setup my equipment. That little beaut will need to go on my list of things to buy…

    Nnscout, I know you’ve mentioned to me before, but what is a NEW radio that does everything a patrolling person would need that is purchasable on Amazon and is in stock? Something rugged that can get through mountains, forests, and valleys within say a 10-20 miles radius? It seems ever radio you’ve suggested is either not in stock and no longer made, or only purchasable via obscure swaps used and beat up. I’m not against buying used, but it would be nice if there were a great modern and new radio.

    Also, maybe give a top 5 base station rigs you would suggest, if they are rugged and portable great, but something with all the bells and whistles. I run an Alinco DX-70TH for my base station that my dearly departed Elmer Uncle gave me years ago as my first radio, but I would like to upgrade and move the Alinco to my truck since it technically a mobile unit. For years now I’ve had my eye on an Elecraft, but those are out of my price range for a while (would need to save up).

    Anyway, thanks for the heads up in regards to the CTX-10

    1. Devin, AWESOME Brother!

      As for currently made rigs- snag up a QYT 7900. For local use, it’s a neat rig, decently built, and I’m prepping a review on one. It’s not a bad option for a VHF/UHF unit.

      1. Deplorable B Woodman

        I just looked up that radio. Damn! It’s small. Could use it for a handheld.

  13. Oh, and you need to come up to Northern Idaho and give a class. I don’t have a “group” since we just moved here and only recently have we got to know some neighbors who are VERY like minded (isolated community outside of town). But I would jump in a second at the chance to take a class from you.

  14. Dave

    Key points to know will be how sensitive and selective is the receiver and how wide range is the antenna matching. The KX2 is amazing in its ability to match antennas making it very versatile for field use. I am definitely looking at this as a possible travel radio that I can tuck into a corner of my backpack with a wire antenna and my smallest CW paddle.

  15. Damn you, Brushbeater! Being the equipment whore that Iam, I am going to have to scrape together some shekels to get this thing and try it out.

    And if you do get the urge to some to North Idaho and give a class, I believe that here are one or two other folks that live in my AO that would be willing to make the trek up there.


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