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KX2 + PA temp woes


Curious as to what PA operating temp KX2 users have experienced without having the KX2 fold back on the power output, or start doing strange things. Yesterday while activating Lava Butte, W7O/CE-188 I experienced some strange going-ons with my KX2. I’ve had the PA fold back the output power with the PA temps reaching 60C on another outing, but this time the radio started sending random CW characters whenever the temp reached 60C, and I was working a few stations. Made it extremely hard to reply to any callers. I had to curtail op time until the unit cooled off. Part of the problem was op error as I was in direct sunlight at the beginning, but even after relocating to what little shade I could find, it still wouldn’t stay below 55 to 60C. I ended up going QRT not wanting to damage the poor little KX2. I read somewhere that Elecraft stated that 62C was the max op temp one could operate the radio and not fold back power output, but haven’t read anything about radio doing strange things while still trying to operate. Thoughts? Thanks. Todd KH2TJ


Hi Todd,
I’ve experiencing my Kx2 folding back power due to heat a couple of times here in the Colorado high country. I didn’t look at the PA temps but I concluded that direct sunlight was the issue. This only started to happen after I was operating for at an hour (CW only…phone would have been worse). So, now I make sure that the Kx2 is in the shade during the warmer months here…not an issue in the winter hi…hi.

It’s not that difficult to put the Kx2 in shade. Most of the time I just need to put my body between the sun and rig.

73, Brad


Hi Todd,

I’ve had overheating problems in the summer as well. I’ve considered repainting the case - black really wasn’t the best idea for a field radio! There is a thread around here with data on how well the Side KX heatsink works. Someone also suggested using some of that electronics freeze spray to keep things cooler. Not sure I want to hike with a can of that stuff, but it’s a ‘cool’ idea :rofl:

I always try to keep my KX2 in the shade, and cut the power back to 5 watts on really hot days. Considering getting one of the Side KX heatsinks… seems like it would make a difference.

Hope you can make it to Salmoncon this year. We missed you last year! We are going to have a Salmoncon S2S party that Friday.



When living in Australia, my FT817ND got a new “skin” in that I added some sticky backed white plastic (as used to line kitchen drawers) on the upper part of the case. That made a great difference to temperature of the rig when I was out on summit in the sunshine, plus it can be removed later without leaving any marks.

73 Ed.


Hi Todd,

My old KX1 doesn’t care how hot it gets but that’s not necessarily a good thing… :slight_smile:

Like Josh I’ve also thought black for a field radio was not the best idea. It’d be kind of neat if Elecraft offered special SOTA versions of the KX2/3 with light colored cases.




My KX2 was in direct sunlight and getting hot on Monday. Fortunately, I had a sheet of white 8.5x11 inch paper with me. I folded it in half and set the KX2 on one half while the other half was used to shade the KX2. Seemed to solve the problem.


Todd & All,

Unfortunately the KX3 suffers from the same heat problem, and folds back at the PA temp of 60C.

I also have to make a conscious effort to keep the radio out of the sun, otherwise it gets too hot.

I too am thinking about getting an aftermarket heat sink.

I really like the transceiver, particularly the receiver, but the PA temperature issue is a real problem.

In my opinion the normal KX3 heatsink is inadequate for its job, even the larger one fitted by Elecraft.




I have the heat sink mounted on mine. As a precaution I try to keep in the shade as well, never an issue of overheating.




Dang, that’s keeping it cool. But what keeping your beer cold??



The Dreaded “Hi T” message is a frequent visitor to my KX2

In Arizona it’s often hot enough to trigger this error message, especially in the summer and on lower summits. I’ve experienced it at temperatures as low as 70F but once it’s over 80F, it’s likely to happen after an hour or so; over 100F and it’s a guarantee (yes I do activate in temps >100F). When it arrives the rig stops transmitting, whether I’m in the shade or not. There have been a few times when I’m sure the other op wondered where I went because it happens mid-stream on a QSO. Usually I can wait 5-10 minutes and it will cool enough to continue on with a few more contacts before overheating again. I’ve found that it is more likely to overheat on higher frequencies, which is one reason I often start on 10m, when the rig is cool, and work my way down.

Unfortunately I suspect this is slowly damaging the rig. It still has a clean enough signal when i view it on a spectrum analyzer, but I do find the frequency is not as stable as I’d like. I’ve recalibrated it numerous times but it always seems to drift upward, more on the high bands.

So, I carry frozen water bottles and blue ice packs and try to create an enhanced heat sink. It’s dry enough in Arizona that this can be safely done - I think in a more humid environment, it could cause some condensation that would create other issues. If I was less lazy, I’d probably try to put together a shade system that would at least delay the error. I have an old car sunshade that I may someday use for that purpose. But that means more stuff to carry and set up.

Keith KR7RK


Holy Cow! :wink: Mine yesterday hit 59C and stayed there off and on and finally when it reached 60C, while sending CW, it would throw in extra long dahs or just random characters. Made it nearly impossible to keep on going with the activation.

Thanks guys for the replies. I’m guessing this can’t be good for the rigs internals :wink: Today went down to the ghetto store (AKA Dollar General) and picked up one of those car windshield thingys. Will make some kind of sunscreen/shade for it…Can’t see purchasing the heat sink for it, yet.

Josh: Not sure yet what the plans are for July. CINCHOUSE wants to go visit our youngest stationed out in New Jersey - so maybe Lobstercon this year :wink: :wink: Will see. Time is approaching fast…

Thanks again guys and see you on the air.

73, Todd KH2TJ


then you have to take 2 alu seat pads with you

One for your but… and the second to cover the kx 2

73 Armin


I almost always try to sit with my back to the sun and then place the radio within my shadow either between my legs or just to the side.

BTW…I think Scott (AK6Q) has an aftermarket heatsink for the KX2



Here is another thread with some data on heatsink/fan effectiveness:


I carry a car windshield reflector as a seat, doubles as a splint if needed along with a sunshade for radio. I wonder if a small fan would help at all, but then again another piece of kit to carry.