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On 10/12/18 8:24 PM, hooverrl@xxxxxxxxxxxxxx wrote:
If you have an RC filter that's getting hot, try adding L in parallel to the
resistor. With properly tuned components, you can achieve higher Q filter
with less heat dissipation. Just ensure that the newly generated frequency
is low enough so it doesn't cause additional RF transmission.
Folks have tried LC low pass filters in tesla coil duty with mixed success.
first off, you have to have L that can stand off a fairly high voltage -
it potentially sees the entire transformer voltage across is
(transformer output at peak of sine wave, other end grounded by low
impedance spark in the gap, or fully discharged tank cap)
Then you have to worry about parasitic C across the inductor - you might
successfully block low frequencies but the high frequencies just come
right through.
The whole idea of these filters was to protect delicate NST windings
from spikes coming from the TC. The secondary winding in the NST has a
lot of turns of fine wire and significant parasitic C within the
winding, so the voltage stress, for a RF pulse, is not distributed
evenly, and you get turn to turn, or turn to core/case breakdown.