The capacitance issue isn't quite as bad as that 3x number suggests. It appears that Oleh has replaced each parallel pair of BS170s with a single IRF510, so the total capacitance is only 1.5x as high.
On Sat, Oct 8, 2022 at 10:20 AM ajparent1/kb1gmx <
kb1gmx@...> wrote:
The IRF510 has virtue but not for this.
THe inpput (gate) capacitance is about 150PF about 3x the BS170s!
The gate threshold voltage is 2-4V (most about 2.7V) and the ACT08 peak is 5V
except for the higher input C of the IRF510 will likely depress that (and make it run hot).
That means the actual mode is likely closer to class B (more current, heat, less efficient).
That it works at all is pretty amazing.? Its still a bad solution.
Allison
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Shirley Dulcey KE1L