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[TowerTalk] Top Hat Switch (mercury)

To: <towertalk@contesting.com>
Subject: [TowerTalk] Top Hat Switch (mercury)
From: i4jmy@iol.it (i4jmy@iol.it)
Date: Thu, 19 Jul 2001 11:54:36 +0200
The many thousands KVs developed at the edge of a vertical aren't 
manageable other than with a big glass or porcelain insulator and a 
knife contactor, just likewise it's used to sectionalize along high 
voltage power lines.
To me, the phisical hat removal doesn't appear as a practical and 
easily manageable solution.

73,
Mauri I4JMY



> ---------- Initial message -----------
> 
> From    : owner-towertalk@contesting.com
> To      : <towertalk@contesting.com>
> Cc      : 
> Date    : Wed, 18 Jul 2001 21:54:22 -0500
> Subject : [TowerTalk] Top Hat Switch (mercury)
> 
> 
> Many people have responded to my previous post.  All responses were 
quite
> valid and appreciated--thank you.  The consensus was to simply cut it 
for 75
> meters and base load it with a variable inductor arrangement (or 
variations
> on that theme).
> 
> My quest for a top hat switch continues.  Why?  Because the thing 
models
> like it will play great!
> 
> I'm building an 80/40 open sleeve vertical.  It will tune all of 40 
at < 1.6
> or so.  It will tune all of 80 / 75 if I can get this hat on and off 
the
> tower.  The base loading is the most commonly used and possibly the 
easiest
> to fabricate.  I live in Minnesota and the base will be 5' or 6' 
under the
> snow in just 6 months.  Making a tunable roller inductor arrangement 
that
> will work in this environment is no simple task either...
> 
> How about this option....
> 
> Mount a mercury tip switch at the top of the tower in a box on a cam-
like
> rotary arrangement (still designing that) and activate a latching
> arrangement using some 1/8" Stainless cable running up the middle of 
the
> pipe from the base of the tower.  I have these little 12 v solinoids 
that
> will pull several pounds about 1/2".  These are details I will work 
out in
> the shop.  My question is, have I simply created a very complicated
> mercury vapor lamp?
> 
> The mercury switch is a vacuum.  The leads are about 1/4" apart as 
they
> escape the envelope.  At 21 volts per thousanth of an inch (handbook 
#), a
> 1/4" gap should handle many KV.  (I only run 1KW max here at this 
time ~~
> 3KV).  I know nothing about the conductivity of mercury.  For all I 
know it
> will explode in this environment!  A buddy of mine said "Hook it up 
and
> watch it.  If it looks like a strobe light mounted on your tower, you 
better
> shut it down."
> 
> I think I can master the mechanical stuff.  What about the switch?  
Anybody
> venture a guess as to how it will behave to RF as a top hat switch on 
my 1/4
> wave monopole?
> 
> Ford-N0FP
> ford@cmgate.com
> 
> 
> 
> 
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> 


List Sponsor: Are you thinking about installing a tower this summer? Call us
for information on our fabulous Trylon Titan self-supporting towers - up to
96-feet for less than $2000! at 888-833-3104 <A 
HREF="http://www.ChampionRadio.com";>
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