BLF177 4M Now I found some time to make a decent drawing of my howework using SchemeIT a nice on-line schematic drawing tool. Offered by Digikey, did not find the BNC connector symbol. Digi Parts sells almost everything it works simple and fast it comes close to the feel and touch of hand drawing. I have used ULTIBOARD and before ORCAD . But Ultiboard is to heavy and complicated for just drawing a small nice schematic. R1 had to be a carbon type 0.5W this was essential to stop oscillations. for R2 10x // 180Ohms metal are used here. This schematic is partly a copy of Phillips application note In the Phillips application R2 has lower value I did not try that. A 10-5 Ohm carbon 1W would do it there too I think.