I bought my KX2 in 2016, It’s been great.
I use it with the internal battery installed, but have to remove it every time for charging, which needs care due to the risk of snagging the battery cables on refitting the back cover afterwards.
I also have the ATU option fitted. It weighs 567grams battery included.
73 Rob G0PEB
Thanks you all, I will get the tuner for sure.
To understand, you basically operate with a external battery with no internal battery most of the time, unless it’s fast and light for alpine summit’s.
Any drawbacks in just relying on an external battery for “non fast and light” summits ?
It uses the same connector for the internal and external battery.
So I have the internal battery just left outside in my transport case and connect it on the summit.
Avoids opening the lid and as mentioned to damage battery and loudspeaker cables. That is very fragile from my point of view.
But you can keep the internal battery installed. It will drain the battery with the higher voltage first.
73 joe
That just says to me that it’s best to just use 3rd party batteries for the ah needed for the day and save money on an Elecraft charger and regularly opening the unit up!
I hope I have that right !
As far as I am concerned, this applies to the KX3 as well. I have the internal charger which is convenient to keep the internal pack topped up. I prefer to power the rig with an external LiFePO4.
YES - it’s not the most modern charging technology… but I’m still quite happy with the XT Power battery (after 5 years).
It fits well in the LowePro bag, it can be charged in the car, it shows the capacity reliably, I can charge my iPhone at the summit, …and it doesn’t cause any hf problems.
73 Armin
Is it really? Don’t Elecraft rigs work with resonant antennas? None of my rigs have an ATU. I’ve never missed it.
…as you read… my opinion! 
73 Armin
Thank you. useful advice @DL6GCA.
Useful to also know that you can get back to 5w with internal battery.
Presume the transistor heat sink is needed as they kick out some heat ? What’s the issues in elecraft not making this standard ?
At risk of starting another topic, I tried the Xiegu x6100 ATU on a random wire with a 9:1. I think it was 84’ with 17’ counterpoise. I had horrible rf issues with mic and headphones picking up RF, that it was a big problem. Not sure what if I screwed up with that or others have experienced this.
KX2 + ATU + Side panels/Lid
Despite having many resonant antennas, the ATU’s ability tune anything and everything makes it invaluable for me. Like when you forget some crucial antenna component, the ATU will still tune up your damp boot laces 
The side panels and lid finish the job off nicely.
I have an internal battery but it is still sealed as I have enough other SOTA Lithium batteries to jump start the Titanic. A KX2 using the internal battery is a neat solution however.
Ask Elecraft… - I don’t have it yet… but it’s been commissioned.
In summer, when the sun shines on the black casing of the KX2, it gets warm quite quickly. It first reduces its power to 5 watts and then it stops transmitting. I always try to keep it in the shade… but sometimes that’s difficult.
The ATU gives you the opportunity to be QRV on all bands with a long piece of wire. This works well with 1:9 and wire… or I, for example, tune my endfed (40/20/15/10) on the other bands.
73 Armin
I would definitely get the internal battery. I have two of them, but rarely need the second one in the field. In fact, if I run at 5 watts, I can get 2 to 3 activations on one charge. Keep in mind that when people say they last for multiple activations, you have to ask how many QSOs. I often get 70-100 QSOs CW. In cases like that, the battery might only last for 2 activations. If you only have 10-20 QSOs, the battery would last for 3-5 activations. If I run at 10 watts CW, I can get about 120 QSOs.
Also, I recommend getting 2 of the batteries; you don’t want to get on the summit and find the battery is dead and not have a spare. If the battery goes dead in the middle of an activation, you can plug the second battery into the external power jack and never miss a call.
Regarding charging the battery. People make a big deal about having to remove it to charge it. It’s very easy. Plus, since I have two batteries, I prefer to alternate them at each charging. At first, it seems a little fussy, but after you’ve done it several times, it VERY fast and easy.
Also, get the internal tuner. With internal tuner and battery, you won’t have all these accesssories you have to plug in each time.
I also have the Elecraft paddle. It’s not the best paddle, but for the way I operate, I like having it on the rig. I strap a small clipboard to my leg and then rubber band the rig to the board. If you operate with the rig at your side, then you’re better off with an external paddle.
Good luck with your KX2. It’s a nice SOTA rig.
I have had a KX2 since Covid ( It was the money we didn’t spend going on holiday). I was initially sceptical about the internal battery but have since started using one as it is considerably lighter. I went for the side panels from gemsproducts, although I must admit to being somewhat nervous about dismantling a new radio to fit them - but actually it was OK. I recently added the internal battery charger, more from worry about constantly taking the back off and causing damage rather than worries about ease of operation. I didn’t buy the batteries from Elecraft at the time, but found that an Ansmann pack was almost identical with slightly better capacity - much cheaper and available in the UK. I still carry a spare (as it weighs so little and can just be plugged in to the power socket, the radio will use whichever source has a greater voltage) but have never needed it! I did go for the ATU, and after accidentally QSYing during an activation disabled the buttons on the microphone (It is in the menu somewhere). The only other thing I use is a splitter which enables the use of wired earphones - which work as both earphones and a microphone (although I do prefer the handheld microphone but on a windy summit the earphones help). I’m sure I got the idea about the battery somewhere on the reflector … Still really like the KX2 … Paul
Oh, not that old chestnut again.
Most SOTA operators like to operate on several bands using just the one antenna. I have a few linked dipoles which I configure as inverted V’s, e.g. 60/40/30/20, 80/60, 20/10/6, and it’s a faff to have to get up and change the links, especially the 30 and 20m ones which I can’t reach without slackening the wire ends. Also, have you tried activating 80m both CW and SSB with your ‘resonant’ antenna?
So, nowadays, I use EFHW inverted-L’s. With the KX2 ATU I can’t tell the difference [in RSTs given and received] from my ‘resonant’ linked dipoles.
As you can see from this topic and many others where the KX2 ATU comes up for discussion, KX2 owners/activators have nothing but praise for the ATU for flexibility and convenience.
In line with my latest enthusiasm, minimalist activations, as well as using short [1.3m long] monoband whips & counterpoise, I recently got myself Elecraft’s own internal battery for the KX2. After about 30 minutes activating the fully charged battery drops from ~12.1V to ~11.5V but the KX2 is still putting out 10W and doing the business.
BTW: Elecraft’s [external] mains charger doesn’t seem to be available in the UK at present (any more?). Maybe Elecraft think it will be superseded by their new internal charger. So I use a Tracer Li-ion/Li-Po charger which meets the same charging spec.
I recently played with an x6100 and it was surprisingly good, but it really is a brick!
I’ve had my KX2 since 2017. Love the ATU, love the internal battery. You can get a higher capacity internal battery (3.5Ah vs. Elecraft 2.4Ah) for less money. I like the internal charger, but only recently got one… taking the battery out isn’t a huge deal but it did eventually cause the speaker connector to become intermittent (easy fix). I like having the real time clock that stays set to the correct time and I don’t have to mess with it!
Yes to internal battery, side protectors, internal ATU. 3S 18650 are widely available without handing £80 to Elecraft. Opening and closing the case is not an issue. The radios are robust and well made.
Yes to a mic. Make one for £5 using this simple video:
Or buy this little beauty for £20
No need for up and down channel keys at the moment due to a bug in the firmware, which elecraft seem to be in no hurry to fix.
Internal battery? Of course!
Use a nominal 13+volt external battery; when much of its capacity has been used, and its voltage drops to just below that of the internal battery, the latter starts supplying the energy.
Backup / increased capacity for external battery, and automatic changeover.
What’s not to like? The internal battery is occasionally used; I top it off a few times a year.
Am I the only one whose KX2 puts out not more than 7W on 10m with a fully charged internal battery? Full 10W on an external LiFePO4.
Carlo, I get:
12 watts with external LiFePO4
10 watta with Li-ion (internal and external)
7-8 watts on 10m band
