KEM has released the linear amp kit for HF 10W. It calls KEM-LINER-HF. The coverage of the amp is between 3.5-21 MHz but the parts of LPF is only for 7MHz.
The maximum output is 10W and it is enough for QRPers. DC 12V power is needed to run the linear amp and input power is less than 1W. It costs 5500(JPY).