The large amount of open space above the main RF board is used by the Internal Battery, Auto Tuner, High Power PA and other options which mount inside the top cover of the K2.
Step by Step K2 Assembly
pictures, by Eric,
PA3CEV
Plus, check out the step by step K2 (and K1) assembly shots at N7TX's great web site.
Picture of all the K2 toroids by AC6KW.
Click on the small pictures for a more detailed view.
