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Date: Fri, 04 Nov 2005 13:06:10 -0500
From: Dexter McIntyre W4DEX <dmcintyre@att.net>
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Subject: Re: LF: toothbrushes
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Laurence KL1X wrote:

> Im hoping to erect a reasonably large but lightweight temp 60m 
> vertical here in the near future but need to keep the insulator weight 
> down to the minimum - I see toothbrushes have been used in the past at 
> the 400W level (?) but Im going to be around that level and concerned 
> over corona _ive made some lightweight corona rings up but still 
> concerned. I dont think Im going to be able to top cap load so looking 
> like something around 365pF and perhaps >3.5mH to resonant

I've used fiberglass rods.  Several sources:   ~10 mm - electric fence
post,   ~6 mm - bicycle flag mast,  ~3 mm from dead pool umbrella spreaders.

Also I've found some weed eater line to be a very good insulators with
high voltage at LF.  However the last type I bought sure wasn't.  After
reading the packaging I found the line to contain some titanium!

Here's a picture of an insulator made with a section of an electric
fence post connected to plastic electric fence insulators.  A hole the
diameter of the rod was drilled in one end of the plastic insulators.
Then rod was inserted and pined with small brass nails.  I tested this
one with 200 pounds dead weight.  The umbrella spreader size rod would
be lightweight.

http://www.w4dex.com/lf/part5/xko_insulator.JPG

Dex, W4DEX / WD2XKO
http://www.w4dex.com/wd2xko.htm