Re: chokes for NST

To: tesla-at-pupman-dot-com
Subject: Re: chokes for NST
From: Terry Fritz <twftesla-at-uswest-dot-net>
Date: Tue, 30 May 2000 21:48:09 -0600
Approved: twftesla-at-uswest-dot-net
Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme
In-Reply-To: <GCEPIBHBALJCAEDPCGLACEAFCCAA.daijin-at-mediaone-dot-net>

Hi Marc,

On my 9/30 coil I use a 360pF capacitor (value not critcal) between each
NST leg and ground.  I then have a 5k ohm 25 watt resistor going between
the legs and the main gap.

I have a string of 1800 volt metal oxide varistors from DigiKey right at
the transformer legs to ground and I put a safety gap between the resistors
and the main gap too.

I use a bunch of low value poly caps in an MMC style string for the filter
caps.

http://users.better-dot-org/tfritz/newcoil/19.jpg

http://users.better-dot-org/tfritz/Filter.jpg

http://users.better-dot-org/tfritz/NSTFilt.jpg

Chokes tend to have unwanted ringing and there is doubt that they do any
good in series with the giant inductance of the NST secondary windings.

Cheers,

	Terry

At 11:05 PM 5/30/00 -0500, you wrote:
>What is a good choke for a 9000/30 NST to stop RF feedback.  Or are they
>needed at all?
>
>many thanks,
>	marc
>