Re: RF chokes

To: tesla-at-pupman-dot-com
Subject: Re: RF chokes
From: Bob Misiura <misiura-at-nccoast-dot-net> (by way of Terry Fritz <twf-at-verinet-dot-com>)
Date: Sun, 07 Mar 1999 10:19:29 -0700
Approved: twf-at-verinet-dot-com

Sam,

I think you should consider winding your own chokes.  The small
"universal wound" chokes with litz wire or magnet wire, sold for radio
applications, tend to arc.  Magnet wire (particularly if close-wound
around ferrite cores) will arc.  Use something like teflon covered wire
or wire-wrap wire for ferrite cores.  A single layer coil is more
effective than a multiple layer coil.

What it boils down to, is if the core material is effective, the
potential difference between individual turns of wire is high.

Put a good quality RFI filter on the low voltage side of your step-up
transformer.  A few high voltage ceramic disks close to the case of the
transformer, line to line and line to ground are a good idea also.  

There are too many variables to consider when talking about a ground.  A
good RF ground is a necessity, in my opinion.  I have run without using
one, at 200 watts, and have destroyed some computer memory.  

In the matter of an RF ground:  A technique that works well in sandy
soil (not too many rocks) is to sweat a fitting onto a 10' length of
rigid copper tube.  Connect the tube to a garden hose, and wash the
whole length into the ground.  Put the RF ground as close to the TC as
possible, and connect it with heavy gauge, wire, copper braid, or
tubing.

Good luck
bob