This was just recently announced via the KX3 User Group on Yahoo:
In response to feedback from KX3 users, we have improved the
transceiver's heat sink, without significantly changing its outside
dimensions. The new heat sink has twice the surface area and much
greater mass, using an 'L' configuration that places part of the heat
sink underneath the rig's chassis. A high-performance, die-cut thermal
gasket is used between the rear panel and heat sink to ensure excellent
Our lab tests show that for a given power output level, the new heat
sink provides up to twice as much transmit time as the original before
power is automatically scaled back under firmware control.
(Larger, third-party heat sinks can still be used, if desired, to allow
extended operation in data modes at full power, or at very high ambient
The new heat sink is already included in production KX3s, starting with
S/N 7292 for kits, and S/N 7255 for factory assembled units. It can be
easily added to existing KX3s using modification kit model #KX3HSKIT
($39.95). Refer to our Spare Parts and Mod Kits page, KX3 section:
If demand is high for modification kits, there may be a brief delay in filling orders.
Within hours, the complaining and whining has commenced. "Design flaw - I shouldn't have to pay!" seems to be the rallying cry. And I disagree with that line of reasoning. After all, the KX3 was designed to put out 12 Watts max. I use my KX3 at 5 Watts, for CW mostly, (OK, I'll confess - I made one SSB contact with it just to test that mode) so I don't have a need for a new and improved heat sink. However, who runs their radio at full output all the time anyway? I may be naive, but even when I had QRO radios that were capable of 100 Watts out, I never ran them to full output. And the few times that I have used it, I don't think I've ever pushed my KXPA100 past the 90 Watt mark, even though it's capable of a lot more. When I do use it, I generally keep it around the 75 Watt neighborhood.
I suppose that if I was a digital aficionado, I would want the upgrade. And the $40 price tag that Elecraft is charging is way less than what third party after-market vendors are charging for their versions. I am assuming that a lot of guys are hoping that the "squeaky wheel" scenario will hold true. I wouldn't hold my breath on that one - and all the complaining IMHO, only enforces the negative connotation about Hams being tighter than the bark on a tree. It's pretty simple when you boil it down to the essentials, if you want to dance the QRO tune, you're just going to have to pay the piper.
72 de LarryW2LJ
QRP - When you care to send the very least!