I have seen a lot of discussion about getting a dummy load for testing the K3 or any other 100+ watt transmitter....
I have an easy solution that I have used over the years from parts I picked up at a swap meet.
I purchased a 50 ohm non inductive resistor rated for 100 watts. These are the cylinder type that can easily be plugged into a large fuse clip. I mounted it on a PCB in series with a 0-2.5 RF amp meter to ground and with a type N female panel mount receptacle on the input.
Now for most applications, this is good up to 6 meters. It is simple and if you remember the ohms law for power, very easy to compute the delivered power. The neat thing is that since it is a clip in, you can put in a 75 ohm resistor of the same rating and calibrate the SWR reading. Have fun.