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RE: half filter?? and what all I need before primary circuit



Original poster: Terry Fritz <vardin@xxxxxxxxxxxxxxxxxxxxxxx>

Hi,

The filter normally uses Digikey # P10501-ND 3.3nF 1600V metal caps costing $0.54 each. If DigiKey is out of stock like they are now, the following near parts could be used. P10502-ND, P10500-ND. Ceramic and other caps can be used as long as the total string value is 250 - 500pF at the rated NST peak voltage.

Cheers,

        Terry


At 07:43 AM 10/13/2005, you wrote:
If you're referring to.001uF/10kV ceramic disk caps, All Electronics no
longer lists that in their catalog.  Too bad - at just $1 each they
would have been an excellent candidate for use in a filter.

I'm not sure that the cap used in an R-C filter is as critical in terms
of its HF characteristics as the main tank cap.  The HF current is low
since it's limited by the series resistors.  And, OK, I *like* the way
the doorknobs look!  And there's no shortage of them on eBay.

Thanks for the paper-plug.  There's a serious shortage of technical
explanation on this topic!

Regards, Gary Lau
MA, USA


> > Original poster: "D.C. Cox" <resonance@xxxxxxxxxx> > > > > If you want to replace the doorknobs which were not really design to > bypass the RF, consider All Electronics .01 uF 10 kV units. Compact > in size, usually 4 or 5 of them in series off each bushing to > ground,gives a nice fast bypass due to their lower capacitance, don't > steal much energy, and are very inexpensive by the bagfull. > > Nice paper Gary --- good design ideas. > > Dr. Resonance > > >I have written a very detailed web page about the how's and why's of > >protection networks - see http://www.laushaus.com/tesla/protection.htm. > > > >Foremost, forget about chokes. In order of descending importance (IMO), > >you want: > >1) Properly set main gap width. No, it's not part of the filter > >network, but a too-wide main gap is the single greatest cause of NST > >failure. > >2) Safety gaps, properly set. Of course if you just open them up, then > >they're useless. > >3) Series resistors AND bypass caps from NST bushings to case. Having > >just the resistors is useless, sorry. > >4) MOV's. > > > >Are the caps really more expensive than the MOV's? Since you're using a > >9kV NST and not a 15kV NST that the filter was designed to accommodate, > >you could use fewer, smaller caps to save a little bit. > > > >Regards, Gary Lau > >MA, USA > > > > > > > Original poster: "Langer Giv'r" <transworldsnowboarding19@xxxxxxxxxxx> > > > > > > Hi, i was wondering instead of using the entire terry filter design, > > > could i just use the MOV's, safety gap, and resistors, and leave out > > > the highly expensive caps and still get a relative ammount of safety? > > > if not... what is the best way to get protection for my 9KV30mA " > > > cheaply and effectively " > > > what is all you need basically before you send off the power towards > > > the tank cap and spark gap? like filter / RF chokes / safety gap? i > > > am still a little confused and before i buy the parts (I am poor) i > > > would really like to know what all to buy. Thanks a million! > > > Daniel from Canada > > > > > > > > >