Re: chokes (fwd)

---------- Forwarded message ----------
Date: Sun, 18 Jan 98 10:59:06 EST
From: Gary Lau  18-Jan-1998 1047 <lau-at-hdecad.ENET.dec-dot-com>
To: tesla-at-pupman-dot-com
Subject: Re: chokes

>> From: Kevin Wahila <wawa-at-spectra-dot-net>
>> I have two 3.5" OD ferrite chokes.  I got some RG 59 and stripped away the
>> outside and wound the choke with the center wire.  I have as many turns as
>> will fit and only come up with 1.078mH.  What should I do now?  Should I
>> just go and used wire with thinner insulation so I can fit more turns?  I
>> thought I needed the thick insulation though.  Any help would be greatly
>> appreciated.
>> choking in NY
>> Kevin Wahila

>Actually, if the chokes are used to protect the voltage source, the turn
>to turn voltage is relatively low. A thinner insulation is quite
>adequate. The problem comes in when you start to stack one layer on top
>of another. The voltage differential could very well break down standard
>insulations. The remedy is to insulate each layer with electrical tape
>or some other type of insulator. In that way, you could even use varnish
>covered magnet wire, provided the inter-layer insulation is adequate.
>	Rick Holland

The wire insulation not only has to insulate turn-turn, layer-layer, and
end-end but also 1st layer to core.  Ferrite is a great conductor, despite
what your Ohmeter may read.

Gary Lau
Waltham, MA USA