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Re: [TCML] NST Terry filter

There is a complete Terry Filter kit advertised on eBay nearly all of the time for $58.80 plus $14.35 shipping. It includes the following parts:
(2) 100 watt 1K ohm Dale resistors
(16) MOV's 1800V  (Metal Oxide Varistor)
(12) 0.0033uF 1600V Metal Polypropylene Capacitors
(12) 10M Ohm 1/2 Watt 5% Resistors

It is offered by the eBay store, Teslastuff, which is Rainy Lake Electronics. Just go to eBay and search for "Terry Filter" and it will come up. There is a complete Terry Filter for sale on eBay right now, too. It is completely assembled and has a safety gap made from brass balls.
Think Positive

----- Original Message ----- From: "Lau, Gary" <Gary.Lau@xxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Tuesday, December 08, 2009 8:51 AM
Subject: RE: [TCML] NST Terry filter

No, the resistors cannot be replaced with chokes of any kind. The resistors are an integral part of the R-C low pass filter. The R-C filter is specifically designed to avoid the resonance that any L-C filter would have. Filters using chokes were widely used until a more thoughtful analysis and simulation was performed, and it then became apparent that L-C filters cause more problems than they solve. See more comments and analysis of NST filter networks at http://www.laushaus.com/tesla/protection.htm

But yes, you can use the two ceramic caps instead of the string.

Regards, Gary Lau

-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
Behalf Of Jeremy Chan
Sent: Tuesday, December 08, 2009 8:20 AM
Subject: [TCML] NST Terry filter

Hey all,
I am trying to build a terry filter for a 15/30 NST according to the following
diagram:http://www.classictesla.com/download/NST_Filter.jpgbut am having
problems finding the 1K 100W resistors.What is their function, and would chokes wound using flyback cable rated at 40KVDC on ferrite cores help in filtering out the hf? If so, how many turns on the chokes would be required?Also I plan to replace the cap and 10M resistor string with 2 1nF 15KV ceramic caps in series on each
side to give 30KV 500pF sans the 10M resistors. Is that workable?
Thanks and regards,Jeremy

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