many thanks ssa :) Maybe a simple VK200 can do the work I think... like this project: http://www.electronics-lab.com/projects/rf/001/index.html that is very similar (well... enhanced ;D ) to the project above.. And I think I'll use a 2N3866 for T2. Maybe a madness, but I'll do some experiments (when I've a little free time) with a Peltier slab over heatsink for T2 and 28 Volts... I suppose that a simple fan isn't enough! A little note about this project: I don't think that is 'crappy' like someone said... remember that it can be made for about five-six euros and goes surely over 1 W rf power! I've see (and assembled) project that use one only oscillator stage with a BC547 rated for 1 Watt at 15V :o ... and that is very crappy, not this one :D Remember that, for irradiation, 2 watts or 3-4 watts is pratically the same... So I must say that is the best projects with free oscillator, simple and cheap ever see. The first stage (that I've built) is fantastic, very versatile and incredibly stable. But... HOW ABOUT A LOWPASS FILTER? maybe a lowpass 18 dB (PI) can be enough... but where can be put? above or below C7-L4-C8?