Jerry,
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When I look at the uBitx LPF, its structure is the same as that of a "shunt first" input Chebyshev LPF.? Does that mean it shunts the high frequencies to ground instead of a "series first" filter?? That would make sense to me as the capacitor in parallel with the input would tend to short high frequencies.? Or do I have that backward?
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There are some differences between the model and the HFSignals schematic.? ?C261 and C262 in the HFSignals schematic are "zero" values and not installed.? I also note significant distortion on the output waveform (across R1).? There is no LPF, so this may be the actual waveform.
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I attached the model with C261 and C262 feedback removed.? I also added the LPF arrangement for the v6, where all bands go through the 10m filter.? I did not change any of the other values upstream of the IRF510.? (the v6 has different feedback values in the emitter of Q90).
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Thank you for your knowledge sharing.
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73
Evan
AC9TU
