599 at Dayton
The599Rpt at aol.com
The599Rpt at aol.com
Sat May 4 09:34:20 EDT 1996
The staff of THE 59(9) DX REPORT will be attending the Dayton Hamvention and
look forward to seeing many of the Deserving DXers for an eyeball.
Look for them at: WX9X QSL Booth
DX Forum (Saturday)
Contest Forum (Saturday)
Hospitality Suite 325 in Stouffers - Friday &
Contest Banquet at Stouffers (Saturday)
We hope to see many of our subscribers and supporters for a chat.
>From Alex van Hengel <pa3dmh at igr.nl> Sat May 4 11:18:37 1996
From: Alex van Hengel <pa3dmh at igr.nl> (Alex van Hengel)
Date: Sat, 04 May 1996 11:18:37 +0100
Subject: Amp Supply Comp
Message-ID: <318B2EFD.6ED0 at igr.nl>
Can anyone help me with the Address for Amp Supply Comp.
Special interest in Email addres, Telephone/fax numbers.
--... ...-- Alex van Hengel. PA3DMH. ( pa3dmh at igr.nl )
Member of PI4COM, Contestgroup Oude Maas.
PI4COM Home Page: http//www.euronet.nl/users/norf/pi4com.html
>From millersg at dmapub.dma.org (Steve Miller) Sat May 4 09:05:46 1996
From: millersg at dmapub.dma.org (Steve Miller) (Steve Miller)
Date: Sat, 4 May 1996 04:05:46 -0400 (EDT)
Subject: Elevated cable runs
Message-ID: <m0uFcLb-00028NC at dmapub.dma.org>
> I believe the key is to bring it to physical (and
> electrical) ground first at the tower base before running it in.
> As a simplified example, if you have a 100 ft tower, and bring the cable
> down to 10 ft, then run it into the shack, you may retain 10% of the
> voltage of a lightning strike on the cable.
It's not that simple - if you look at a lightning strike in the frequency
domain, a 10 foot height presents a very high impedance to ground when
the wavelength is 40 feet (quarter wave transformer) or an odd
multiple thereof. Thus, for the frequency content of a lightning strike
which occurs at these wavelengths, cable potentials are nearly 100% of
the lightning strike voltage (across the tower). A direct strike, or even
a near strike can result in extremely high potentials on the cables.
> because the tower appears as an inductance to the quick pulse of a
> strike, and the cable at the 10 ft level appears as a "tap" 10% above
> ground potential of the tower/inductor.
This is an over-simplification. Even if it were a completely valid
approximation, I wouldn't want 10% of a lightning strike coupled to my
Also, inter-band interference may increase if you ever want to receive
while transmitting on a second rig. Current induced on above ground
cables may compromise receiver performances unless you have a very good
(low impedance) ground connection at the entrance to the shack.
Above ground cables are usually easier to implement and may perform
adequately, but buried cables would improve the situation and provide better
lightning protection assuming a suitable grounding scheme is implemented.
Steve Miller WD8IXE
millersg at dma.org
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