Simple, Cheap and Effective DIY Heatsink for KX3

Hi everyone,

I mainly do QSOs in digital modes. Mainly PSK31 and JT65. Recently I’m also using WSPR to test my setup efficiencies.
Each of those modes (as most of the digital modes) work by pushing all power for a certain amount of time, usually about 1 or 2 minutes. Even working with “only” 5 Watts, the internal temperature of the KX3 quickly rises, and when it goes to 60Β° C tha KX3 stops working full power.

Also, even most important, as the temperature rises the VFO tends to drift. For most of the digital modes, drifting too much, means no decoding on the other side.

It is crucial to keep temperatures as low as stable as possible.

Recently a few people decided to build heatsink add ons for the KX3. All very well done, an most very good looking to perfectly suit the KX3 look.

The main problem is that they are not cheap… they all cost around $100 + shipment.

Being a “maker” (I like to build things myself) and thanks to my experience with PC modding, I decided to go with a cheap and effective solution that is also not ugly.

I bought 5 graphic CPU heatsink 35×35 mm (14 mm high)


and some thermal adhesive tape (by Akasa 80×80 mm)


I dismantled the “heatsink” bar of the KX3 and took all the paint out with sandpaper on both sides. The attached the 5 square heatsinks with the thermal tape to the Elecraft heatsink bar.

Part list

The thermal tape is this one:

You just need one of this thermal tape. It is 8x8cm and it’s enough to cover the heatsink surface.

While the heatsink are those one:

You need 5 of them.


Total cost less than 30 Euros and 20 minutes of work.

Here are a few images of what it looks like.

It’s like my KX3 now has hairs πŸ˜€

Anyway, the important is that tests say that performances are very close (if not better) of most of the “commercial” solution. With 5W it never goes above 45Β°C.

If you want something “professional” go for the commercial solutions, you won’t regret it. But if you are low on budget and/or like to do things yourself then this is a nice and working option πŸ˜‰

72/73, Andrea IU4APC


10 thoughts on “Simple, Cheap and Effective DIY Heatsink for KX3

  1. Hi Andrea!
    I applaud the initiative, however as you point out, the heatsinks you used were designed for forced-air applications on a graphics chip. This means they have too little spacing between the fins to generate much convective air flow. Still, I’m sure they work better than the stock heatsink!

    Howard Hoyt

    • I totally agree with you.

      But it’s also true that the heat generated by CPU/GPU is much higher that the 30Β°-60Β° of the KX3.

      Also, if necessary, with this design, adding a small fan is a real snap. I won’t do anyway πŸ˜€


  2. Could you list the sources for the heat sink and thermal tape?

  3. Hmm why on earth don’t they ship the heatsinks to the UK???

    • That’s one of the reasons why I decided to go with the DIY solution πŸ™‚

      • No. The ebay companies in your shared links won’t ship to the UK. It’s crazy!

      • Sorry about that.
        But if you look for “heatsink 35×35” probably you can find something available in the UK as well. Mine is high 14mm. I’ve seen that there are also some with a lower profile but 14mm is a good measure to have good performances with a workable size.

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