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Re: [TowerTalk] homebrew low voltage surge suppressors?

To: TowerTalk <>
Subject: Re: [TowerTalk] homebrew low voltage surge suppressors?
From: Red <>
Date: Wed, 27 Sep 2006 17:32:06 -0500
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The inductor core in the ICE suppressor saturates due to the low 
frequency components of a surge and becomes a short circuit, thus 
relieving the gas tube of much of the current.  That can happen before 
the gas tube begins to conduct, as gas tubes exhibit a delay.  In 
addition, the suppressor appears as a mismatched load when a surge is 
applied (combined operation of the inductor and gas tube) and much of 
the surge energy is reflected back to the antenna.  Of course, the 
antenna  is also a mismatched load to much of the surge energy, so some 
of that energy is reflected back to the surge reflector, and goes back 
and forth.  In the process, energy is dissipated in the feedline.  
Spreading of the energy among several components of the system helps 
these small suppressors to survive fairly large surges. 

The gas tubes used are typically rated for up to 20,000 Amperes. Their 
life is limited at that current level, though.  The voltage across them 
while they are conducting is typically 15 to 20 Volts.   Gas tubes 
operate just like spark gaps.  The advantage over a simple spark gap 
(spark plug, for example) is that the characteristics are regulated by 
the composition of the gas and the electrodes and by the gas pressure in 
the tube.  Thus they can achieve high operating voltage when not 
conducting, low operating voltage while conducting, and stable 
characteristics that is independent of atmospheric conditions of 
pressure and temperature.  The working parts are protected from 
contaminants and oxidation, which affect simple spark gaps.

A major component of the PolyPhaser and ICE suppressors is the blocking 
capacitor, which limits the energy that is passed to the rig while 
energy is being dissipated in the suppressor, feedline, and antenna.

These devices work quite well.  Similar technology and components, 
including gas tubes, have been widely used for years to protect 
electronic components from surges.  Read _Protection of Electronic 
Circuits from Overvoltages_, by Ronald B. Standler, 1989; John Wiley & 
Sons, Inc., particularly Part 2, Chapters 7 through 15, for information 
about gas tubes, varistors, avalanche and Zener Diodes, semiconducor 
diodes and rectifiers, thyristors, impedances and current limiters, 
filters, isolation devices, and parasitic inductance and how these 
devices may be used to protect electronic equipment from overvoltage 
stresses such as those associated with lightning.  This book may not be 
available in many public libraries but is available on inter-library 
loan from college and university libraries.

73 de WOØW


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