I=92ve built a 40MHz amplifier based on a BLF177 RF FET. The circuit is similar to the 108MHz class B example presented in the datasheet, except I have recalculated the input/output matching networks for the lower frequency. The amplifier works to a point, but performance is poor. With Vds=3D50V Idq=3D0.1A and 1W input I get about 10W of output power, this is far lower than the 20dB gain I=92m looking for. I can=92t see what the problem is. I=92m pretty sure the matching networks are correct, the values are not too far away from the those given in the28MHz class AB example also in the datasheet. Can anyone take a shot in the dark as to what the problem may be?