Alex said:
>I have modified several amps by replacing the conventional
>Switch/PlateCap/Inductor/Load Cap with a simple Pi filter.
How do you meet FCC Part 97.307(d) with such an arangement?
In a class AB amplifier, the second harmonic component of plate current
is 6dB down on fundamental, so you need another 34dB out of the tank circuit at
the second harmonic, which the sums suggest you won't get without an
embarassingly high Q.
In view of the costs of tank circuit components, I don't believe
manufacturers would have gone to pi-L networks unless they had to.
If the Radio Regulations on Spurious Emissions are to be followed, even
40dB is not enough attenuation. Fortunately, despite Administrations signing up
to the regs, they've quietly forgotten about implementing them.
73
Peter G3RZP
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