[Top] [All Lists]

[TowerTalk] Top Hat Switch (mercury)

To: <>
Subject: [TowerTalk] Top Hat Switch (mercury)
From: (Ford Peterson)
Date: Wed, 18 Jul 2001 21:54:22 -0500
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?


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 

FAQ on WWW:     
Administrative requests:

<Prev in Thread] Current Thread [Next in Thread>