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[TowerTalk] vertical antenna siting -- over steel roof or groundmounted

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Subject: [TowerTalk] vertical antenna siting -- over steel roof or groundmounted
From: w7why@harborside.com (Tom Osborne)
Date: Sun, 03 Feb 2002 02:27:42 +0000


Pete Smith wrote:
> 
> I'm considering installing a trap vertical (HF-9V) for 80-10 >meters.  I have 
> two possible locations for it.  One is in the >center of a 30 x 40 foot steel 
> building roof, about 10 feet off >the ground (and with a slight slope). 

Hi Pete. 
 
An antenna over a metal roof works very well, but you need to
bond the pieces of roofing together.  A lot of roofs are put on
with nails that have little rubber washers to prevent leakage. 
When they start to corrode, you get all sorts of crud between the
metal panels and they can act like a bunch of rectifiers and give
you TVI fits!
A friend of mine had that problem and you could see arcing when
he ran the Alpha at full power.  73
Tom W7WHY

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