[Amps] low pass filter fail

[peter chadwick]

I don't know how much harmonic attenuation you would get in the matching network for a solid state 2m PA, but at 500 watts output, it might not be as much as 30dB, and then you need 40dB from the stubs. So a low pass filter has its attractions, if only as an additional filtering stage. A valve PA, on the other hand, is likely to start from a better position in that the harmonics will be attenuated by the relatively high Q tank circuit.

One has to consider what variety of LPF, too - Butterworth, Tchebycheff or Cauer-Tchebycheff, although that last one might be a bit impractical at these frequencies. The variety also affects the cut-off frequency definition.

73

Peter G3RZP