I've built a RF amp based on a slight modification of the WA2EBY design (http://py2nfe.com/Arquivos-pdf/linear-kossor1.pdf). I'm currently testing it using an 8MHz, 10Vpp signal at the input and a 50ohm dummy load at the output. However, this testing is limited since the IRF510 MOSFETs are becoming very hot very quickly, even with heat sinks attached. I'm slightly puzzled as only 0.5A is being drawn from the +28V power supply.

Anyone have any suggestions? I've attached my schematic for reference, or you can open it here http://imgur.com/3ULJE55.

 

Hello,

How did you adjust the bias of the fets?
This is described in part two of the PDF's:
http://py2nfe.com/Arquivos-pdf/linear-kossor2.pdf

Bertus