2SC1946 28 Watts FM-broadcast (87,5-108MHz) rf-amplifier ======================================================== All component values are drawn on the .comp and .silklayer bitmaps, with the following exception(s); 1.- all four (4) coils (in the lowpass filter section) are: 3.5 turns, 8 mm DIA., 1.2 mm CuL closewound i.e. no wirespacing. Notes CuL = magnetwire, enameled copper wire, insulated (rigid) copper wire e.t.c.. (Note: 2 mm equals approx. to #12 A.W.G 1 mm equals approx. to #18 A.W.G 1.2 mm equals approx. to #17 A.W.G 0.8 mm equals approx. to #20 A.W.G 0.3 mm equals approx. to #28 A.W.G.) (I) all diameters are measured from the inside of the coils, i.e. 'internal' diameter. (II) make sure to mount the rf-transistor on a appropriate heatsink and use some thermal heatsink compound between the flange of the transistor and heatsink! (Thermal resistance heatsink at least 6°C/W.) (!) by the way, it's always smart to study the 2SC1946 datasheet for additional information (C)2006 by Harm (Helix, Inc.). The Netherlands.