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50w+ SOTA portable HF transceiver with built in ATU


I’ve had a trawl of the reflector and elsewhere but not found a definitive list so I wondered if anyone had any recommendations for an HF transceiver with 50+ watts power and a built in ATU? I use LiPo batteries for power and am happy with external batteries but an external ATU is more boxes and cables. I appreciate the Elecraft KX3 with optional ATU fits the bill, if a bit on the pricey side. Does the iCom 706 MkIIG have a built in ATU? I would possibly stretch to an icom 7200 but I’m guessing that’s getting a bit on the heavy side for a backpack transceiver. I use a SOTAbeams quad-bander dipole but would like the flexibility to use an end-fed wire antenna for tricky summits like my recent visit to Pike of Blisco in the Lake District which was totally unsuitable for setting up a dipole, so HF was ruled out.

Hoping to be a 2E0 or even an M0 within the next couple of months.
I won’t be giving up the FT-817 however!

Thanks, Mark.


Hi Mark,

50w is not a common power level for typical radios so usually it is achieved by lowering the drive on a 100w rig.

There is an efficiency penalty when using a 100w rig at lower powers. the bias current that sets the driver and final amplifiers for linear operation is ok for 100w but is more than you’d prefer to be draining your battery at 20 to 50w.

However many operators use 706 series (inc 7000) or 857s. I used mine once, it flattened my battery more quickly and I regretted carrying the extra weight as I didnt make any more contact than I would have with the 817.

Overall it is probably more efficient to use an external amplifier when necessary. Increasing the output power has only a slight increase in received signal (10db from 5w to 50w = 2 real S points). I do concede that poor hf conditions do make it attractive to increase the output power.

As for the ATU, using resonant antennas with a known impedance solves that problem for most operators. I have an LDG ATU that has only been used a few times on summits. The linked dipole produces a good result and so far, has not drifted off frequency. So I no longer routinely carry the LDG tuner if I’m using the linked dipole. EDIT: The above comments on ATUs did not respond properly to your question about ATUs - I think the task of matching an end fed antenna is best done by the various specialist or home brew matching systems. It is a very high impedance on a half or full wave antenna, so needs an appropriate type of ATU. Most commercial ATUs have a limited impedance range that does not go high enough for an end fed half or full wave antenna. One source of a suitable matching unit would be Sotabeams.

Hope this helps.

73 Andrew VK1DA VK2UH


I’ve used my FT857D a couple of times for SOTA … but never at 100W usually 10-25W. I used a Dentron Jr. Monitor Tuner which is fairly liteweight (well… when your carrying a 100W radio and 9Ahr // LiFeP04 battery it’s fairly liteweight).
The Dentron will pretty much match anything to the radio…

oh, and re the ICOM7200… it would have a problem with the voltage range on most portable battery options…



I’m not sure many options exist that fit your requirements exactly.

Some suggestions;

  1. Build the 50w Hardrock amp and included ATU (www.hobbypcb.com) and use it with your 817. It’s easy to build (I have one) and Jim V the designer will help with issues.

  2. used Elecraft K2/100 plus and external ATU. You could build one as the kit is available but I’ve periodically seen a k2/100 on eBay ready built for what I consider really good prices.

Have fun and this helps.



Hi Mark,
If you were simply talking portable, there are few options - Yaesu FT450D ICOM IC-7200 Kenwood TS-480SAT, plus of course the Yaesu FT-857 (or the new FT-891 replacement for it).

If you want to backpack, as others have said, the size and weight of these rigs could become a problem. I use an FT-817ND plus a hombrew amp to get me up to 35W - there are several 50W amps available either as kits or ready built.The downside is the extra cables and battery.

If you can pick up a good used Yaesu FT-857 and don’t mind carrying the extra weight of the rig and a larger battery, that’s probably the most cost effective option. The 857 however is the one rig of the ones I mention that doesn’t have a built in ATU, so either an external ATU or a resonant antenna is needed.

73 Ed.


One of the reasons that there aren’t a lot of 50W HF radios is based on the way that signal strength is measured. In order for a receiving station to hear you at S6 instead of S5, you would need to increase the power of your radio 4x. So if you were putting out 6W and being received at S5, you would need to put out 24W to be received at S6. To get to S7 in this scenario you would have to put out about 96W of power. As long as your signal is above the noise floor then you’ll be fine, unless you’re competing with a higher power station on the same frequency.

From a portable standpoint, present amplifier and battery technology allows for ~20-35W of power on SSB before the size and weight become prohibitive for most activators. People have been known to lug large batteries to summits before, but once you cross the 20-35W threshold there are some seriously diminishing returns.

There are a variety of portable backpacking amps available. The HardRock, MX-P50, miniHFPA, and even the K5BCQ kit are good options to look into. There are even more homebrew amp projects scattered about the internet. Good luck!


As others have said, more power gets rapidly hit by the law of diminishing returns. Most people having an 817 and wanting more power would look at an external amplifier like the HF Packer or it’s clones. http://www.hfprojects.com/

For EFHW antennas, you need a dedicated tuner, the internal tuners in most rigs are not designed to match impedances that high. Take a look at the web site of Steve Yates, AA5TB. He has several pages dedicated to explaining the EFHW antenna.


73, Colin G8TMV


It’s a difficult decision in many ways Mark. My view is you want a SOTA station that is built out of multiple components so you can pick and choose what to take for each activation. If you have a big heavy radio, you have to carry that on every activation. If you have a lightweight radio you can always add an amp and its battery and decide whether you need the amp or not and save weight.

As you have an 817, an outboard amp would make sense. As most have said, a 50W amp gives the best signal boost vs. weight penalty when you consider you need extra batteries. There are nice second hand Japanese items from Tokyo Hi-Power that come up on eBay now and then. There are some nice Chinese ready made amps too. There are complete kit amplifiers about if you want to make something but probably not suitable for a first project.

There are lots of cheap ways too. PA kits on eBay are under £20 but they need boxing, relays, control circuits and most of all, output filters adding. Do not be tempted to use one of these, or a CB amp unless you have an output filter. We amateurs often complain about interference to our bands from domestic goods that are poorly designed. So we need to ensure we don’t produce interference ourselves!

Finally, don’t forget that 5W of CW has about the same “ooomph” as 85-90W of SSB. CW doesn’t weigh extra or need its own battery. You just need to learn it. Something to consider rolling into your journey to a 2E and thence M0 licence.


Hi Mark,

I agree especially with Andy’s point above. As a compromise, you can assemble your kit as one unit before you set off. Either tape it together (I have used decorator’s masking tape, as it is quite strong enough, and doesn’t leave a sticky residue) or fit it all into a box with connections in place. A search of this Reflector will show a range of ideas, from the elegant to the Heath Robinson!

Finding out what works best for you is all part of the fun.



Thanks for all the helpful replies. I suspected that apart from Elecraft offerings there isn’t anything that fits this (albeit somewhat contrived) scenario. The question has thrown up some options I definitely didn’t know about which is great and I will explore.

I have hiked with quite a heavy backpack (12kg+) on many an occasion and at the moment with my fitness level this isn’t an issue. Understood about flexibility, and leaving things behind that aren’t needed. The FT-897 with attached ATU seems like a good compromise, but I guess an FT-857 with appropriate ATU is a similar, probably lighter, solution.

Are there any SDR based solutions out there currently for field operations?

Kind regards, Mark.


CW is definitely on my list thank you for reminding me!


Technically the KX2 and KX3 are SDR radios, they both have QSD/QSE circuits and do most of the modulation/demodulation in software. A more reasonably priced SDR is the MCHF kit (http://www.m0nka.co.uk/), though that will require some assembly and you’ll have to buy an enclosure from a different source or build your own. The Elad FDM-DUO (http://ecom.eladit.com/FDM-DUO/en) is a field portable SDR unit that doesn’t need a PC, though it costs about as much as a KX2.


Hmmm… MCHF looks very, very interesting, and could be built into a single waterproof case with PA and ATU…
I have seriously considered the Elad FDM-DUO, it’s a very nice piece of kit. I think it would need to be carefully protected for field use however, and would still need PA/ATU.

I can do electronics, so kits are definitely being considered.

Many thanks for the answers, Mark.


… The FT857D has VHF/UHF for FM-SSB-CW operation too… so it’s more versatile than the 991 IMO…


As the owner of both systems, I would much prefer to take the 857. If your day job is being a Himalayan Sherpa though maybe the 897 wouldn’t pose a problem! Good luck with whatever solution you choose



I have been using FT857, IC 706, IC 703, KX3 and KX2. As said before by others, the 857 and 706 drain batteries. Both being marvels but not really sota fit.
I use the KX2 now and I am very pleased with it, antenna is a linked dipole or an end-fed. And I make transatlantic qso’s too. Furthermore the KX2’s internal battery lasts long time, recently I did 5 summits in Germany, put the KX2 on 5watts and did 5 times about 1hours on each summit. I had twice contact with the US.

Remember you can have a lot of fun on summits with non transatlantic qso’s too.

My back-up radio is an MTR3B now.



ICOM IC-7300 with €30 3rd party metal protector side panels and an at least 5, better 8 or 10ah LIPO/LifePO battery to power it. Not light!

73 Ed.


It appears Martin Lynch & Sons has bought a batch from the guy in Germany making the protective side panels -


Ed, do you have a list of the names and addresses of people who are daft enough to spend a bullseye on 2 pieces of painted mild steel? I would like to further separate them from the obviously excess amounts of cash they have. :slight_smile:


I don’t think you’re paying for the steel, Andy, the holes are the clever bit - they are a special shape, and hard to come by :wink:


Actually after posting this, I realise it’s getting somewhat off topic, but Mark asked about portable SDR rigs. As regards the side panels you could make them yourself. The favourite kitchen cutting board material comes to mind as strong enough and light enough. Without some kind of protection I wouldn’t consider taking an IC-7300 portable in any case. These side panels are cheaper than the ICOM handles for their 7200 (which serve a similar purpose) by the way, especially if you buy direct from the guy who makes them rather than through a radio shop (as you can see from the prices).

In any case in an effort to try to get this back on topic - my conclusion for Mark would be, if you want to backpack to a summit go for a small rig such as the 817 or KX3 and then look at an amplifier to take you up to the 35-50w level that you only take when you really think you need it. Two years ago 5w of SSB was enough to get a DL-VK S2S QSO, now I would say you need 25w for a similar distance with the propagation the way it is. Considering we are still going down in the sunspot cycle perhaps planning to have 50w available is not a bad idea.

73 Ed.