Original poster: "vfo" <vformigari@xxxxxxxx>May I suggest the publication of a list with the significances of the numerouses abbreviations used by you experts, as SISG, IGBT, RSG a.s.o.? (I live in Rome, Italy, and am not so familiar with your language...). VFO. i.e. Vittorio Formigari, not Variable Frequency Oscillator... http://xoomer.virgilio.it/vform/tramroma/index.htm