RE: EMI filtration Questions

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Dave Hartwick by way of Terry Fritz <twftesla-at-qwest-dot-net>" <ddhartwick-at-earthlink-dot-net>

Gary,
I issued  similar though much less specific questions on my orignal post.
What are the goals?

Mine are very practical.
1) Minimize destruction of home appliances
2) Minimize neighbor's irritation level

I wonder if commerical filters are of any real-world benefit at all. I'm
sure someone has studied this--scoped the AC mains, for example. I've never
used a commerical filter so I don't know.

If these filters only remove a small fraction of the RF garbage, what's the
point? They ARE cheap however, so the "Why not?" philosophy is plausible.

Dave Hartwick



Original poster: "Lau, Gary by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<Gary.Lau-at-hp-dot-com>

We can argue about EMI filters all day, but no one to my knowledge has ever
defined exactly what it is that we're trying to accomplish.  Unless the
objectives are rigidly defined, gauging success is impossible.  Are we
trying to:
* Eliminate conducted line interference at the tank frequency?
* Eliminate conducted line interference at MHz frequencies, due to
parasitic oscillations?  GHz oscillations?
* Eliminate differential or single-ended conducted line interference?
* Eliminate radiated interference at above frequencies?
* Eliminate high voltage transients?  Single-ended or differential?
* Eliminate all vestiges of interference on radios, TV's, and cordless
phones in the house?  Neighbors house?

If you answer YES to all, you're being unrealistic and demonstrate that we
really don't have a good handle on the nature and definition of the
problem.  I also use a commercial EMI filter on my coil, but I make no
claims about its effectiveness.  I did it because it was cheap and easy,
but I did not make any before/after measurements, again, because we don't
have a consensus on what it is that we're trying to reduce.  I can't
measure what isn't defined.  Where did you get the 400-1200 Amp pulse
figure?

Gary Lau
MA, USA

>Original poster: "robert heidlebaugh by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <rheidlebaugh-at-desertgate-dot-com>
>
>I like your post, but I take the reverse wiew. You state the use of
perfect
>commercial filters. The last perfect man on this earth was treed in
>palestine by Italians. This is my view. No commercial filter is made to
take
>the 400 to 1200 Amp pulse power of a TC. Commercial filters are good at
what
>they do, but farr from perfect so I use commercisal filters for what they
do
>well and use my own double Pi filters in each side of the power input to
>take the brute force power of the TC ahead of a commercial filter. My
>filters are not perfect, they take the slam of power while the commercial
>filters clean up the remaining mess of ripple.Both doing there best.
>     Robert  H