Usefull links that I have found recently.

How to work with a Tube PA, the tune procedure

A blog that I stumbled upon, that among others describes SDR picture by picture. Very well made explanations.

Found this tutorial on Youtube: "Circuit Board Etching"

This is a rather nice video of how to make your own PCB's

DVD Stash Box! What would you put in it?

Things that one can do with old computer hardware.