KXPA100 for SOTA?

Just curious… anyone taking the KXPA100 out with their KX3 for activations? If you are… with what battery?

EDIT. I’m not thinking of getting on for SOTA specifically. I have a KX3 I’m using for SOTA and I like it so much that I’ve been thinking about about using it as a base rig (replacing my Kenwood 450s) in the shack. For shack use I’d want to add a KXPA100. Which got me thinking… I wonder if I could take the amp long for SOTA on activations where it wouldn’t be a big deal to take extra weight, such as drive up’s and short hikes OR in summits that may have a lower elevation and the extra power would be helpful.

I took one up for KU6J memorial activation last October. Far too heavy in my opinion unless your foot journey is very short.

The hard rock 50 watt with atu is much smaller and lighter.



I have used the KXPA100 for special occasions, such as an organized EU-NA event. I try to do a “heavy activation” for those types of events, so a pick a low 1-pt summit that won’t have “mountain weather” and I can hang out a long time. I pick something with easy access so I can pull a garden wagon, and that way I can take a car battery without worrying about running out of power. Using a car battery isn’t a very SOTA-like answer, but hey, I really want the DX S2S. Having done this a few times, I have a sense for how many amp-hours I consume with how I’m using the equipment. I use on the order of 3 amp-hrs of battery capacity per hour. Knowing this, in the future I could use my LiFePo3 batteries instead of the car battery. I just bought a miniHFPA Packer Amp, and once I find time to solder it up I won’t take the KXPA100 for any more SOTA activations.

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I carry one sometimes. The battery I use is the Bioenno 9Ah and that works just fine at full power for a couple of hours. It does indeed add substantial weight to the pack. If I’m hiking for a couple of hours it’s fine, but for longer hikes I trade that weight for additional hydration.
I actually think a 100 watt mobile such as the FT891 or 857 would be lighter overall than the KX2 and KXPA100, but I like the performance of the KX2 and it’s what I’m used to having on the activations. If you’re using the KXPA100 with the KX2 (or KX3), it’s a seamless integration - pretty much plug and play.
I did take a look at the HardRock50 and may eventually build one, and it is lighter. But it does not seem to me to be as rugged as the Elecraft unit (which is important here in rocky Arizona), and of course it’s 50 watts less. I’m not a power hog but the amp does make QSO’s easier, which is nice when I’m looking for a more relaxing activation.

73 de Keith KR7RK


I have a Hardrock 50 which I built. I’m not sure its any more or less rugged than the KXPA100 and volumetrically it is noticeable smaller (and lighter).

Oddly enough I just acquired an 857 (and had it tuned up by Thom Davis (W6LDX in AZ) as I wanted a > 10 watt rig, something that had VHF/UHF SSB and having used the HardRock and KXPA100 on many NPOTA and some SOTA activation didn’t really enjoy all the fiddling with wires etc etc.

I think the HR50 has the same level of integration with the KX2/3 as the KXPA100.


I use an FT857D when I want more power for special events (like the NA-EU S2S event). I have a 9Ahr LiFeP04 battery pack I made and running the radio I get about an hour or so of 25-50W operation before the battery gets around 11V and the 857 doesn’t like that… it works ok my end, but I get reports from the listeners that something is up… Anyway. I like the FT857D for the versatility and you can pick them up with filters used for around $650…

Not sure I would give up my base rig (that I already have) to run a Kx3 plus an Amp, although a friend of mine, for example, is always commenting on how well his Kx3 does listen compared to an ICOM 756ProIII (which I consider a great radio)…

Ok… Rambling thoughts done.
GL with you decision… I’d do the 50w amp I think… :wink:

Richard // N2GBR

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Used KXPA100 a few times, all on short/easy hikes. Battery: LIFEPO4 4S2P with about 20-30W output on CW for about 1 1/2-2hrs.
I often accompany KI4SVM where he brings his Hardrock50, which definitely accomplishes the mission.
In shack, the KXPA100 tethered to KX3 virtually turns it into a QRO rig with all control through KX3.

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The Hardrock certainly seems like it would be the way to go if you were specifically looking for an amp for SOTA. Any who knows… one day I might pick one up. But the KXPAs main purpose would be in the shack and I might occasionally take it /p. Then again I’ve never seen one in person…and sometime just seeing something changes everything!

What a great idea!

I just got a Bioenno 4.5Ah - I got way more time on it that I expected. Very happy with it.

Curious about your thoughts here. I’m a new ham and I’ve not had the KX3 long so I greatly value you opinion here.
Let me share what led me to this idea. I’ve only had the KX3 a few weeks and I recently had it in the shack trying to get to know it a little better when I stumped on some good DX with a nasty pile up. Tried to work him for 30-45 minutes with the Kx3 to no avail - to be expected with a 10 watt rig and endfed antenna right?. So I moved the antenna over to the Kenwood… BOOM! Massive difference in receive audio clarity. So that got me thinking about selling the Kenwood and putting those funds in the an amp for the KX3. It looks like, although its pricey, the KXPA100 has pretty seamless integration with the Kx3 so I thought I’d get one… plus… I can take it sota when needed.

Failed to mention there that my base rig is a K3S… but I respect the performance of the 756ProIII as that was my previous rig.
I’m in no way an expert on any of this, but it sounds to me that in your situation the AMP would be a good investment…

Given the choice between an FT857D and a KX3+Amp, I’d choose the latter… but FT857D’s are fairly inexpensive (for what you get) and using them in a low noise environment (on a summit) they perform well… not a rig id want to use in a contest though (considering what other choices I have).

Not sure any of that helps you, sorry.

Best bet is to find someone near you that has that set-up and see if you can go play there… as you know… “opinions are like arm-pits…” as the saying goes…

ps. A British accent works well to break into pile-ups… I’ve heard… :wink:

Richard // N2GBR

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I should mention that I have an 857d in my car. I can remove it in 10 or so minutes but I wouldn’t want to use it has an everyday base rig given the choice over the Kenwood just because I wouldn’t want to take it in and out. I have not taken in SOTA yet as I don’t have a big enough battery.

A K3S as a base would be AWESOME!

I am almost done putting together my miniHFPA amp and am looking forward to taking it on some SOTA activations to help me get more QSO’s in these difficult propagation times. Hope it works when I turn it on!!

Dave, AE9Q

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Let us know what you think once it’s together and you’ve done an activation with it.

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Hi Keith - like the callsign - ‘almost’ a Pallindrome - neat! - though maybe not so good on CW - a bit of confusion me thinks :grin:



Really? Which one? We have several to choose from. Some seem less intelligible than others (to me at least).


I presume he’s talking about Karl and his 5W :grin:

Mine… Originally from Teeside…, several years in the South of England and lots of Overseas time and now 20years in USA…

Not sure what you call that accent…

Richard // N2GBR


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