[TCML] NST Terry filter

[Paul Brodie]

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.
Paul
Think Positive

----- Original Message ----- 
From: "Lau, Gary" <Gary.Lau at hp.com>
To: "Tesla Coil Mailing List" <tesla at pupman.com>
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
MA, USA

> -----Original Message-----
> From: tesla-bounces at pupman.com [mailto:tesla-bounces at pupman.com] On
> Behalf Of Jeremy Chan
> Sent: Tuesday, December 08, 2009 8:20 AM
> To: TCML
> 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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