I remember seeing several articles in the 50's that used automobile spark
plugs as lightning arresters. That was when you could get a plug w/o a
built in resistor. Can you do that today? Comments?
Roy W4ONU
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of jimlux
Sent: Sunday, September 12, 2010 12:38 PM
To: K1TTT
Cc: towertalk@contesting.com
Subject: Re: [TowerTalk] Lightning Protection Question
K1TTT wrote:
> Of course most of us do have 'spark gap' protection at the tower and shack
> end automatically. Just look at all the short gap paths on so-239's that
> are typically used on baluns and switchboxes, in most cases you are
looking
> at 1/4" or less from the center conductor to the case. That pretty much
> limits the voltage difference at the ends to a couple thousand volts
anyway.
>
>
Yeah.. but if that gap fires, the connector is (temporarily, at least)
unusable because of the carbon track. If the goal of the "tower"
protection is to reduce hassle having to go an replace/repair relatively
cheap components (e.g. $10 relays vs $1000 radios), a well designed
static gap might take the hit, and need no attention later.
(practical note.. breakdown voltage on 1/4" gap along an insulating
surface is typically about 5-6 kV... the rule of thumb is 1/3 the
voltage of a free air uniform field gap of the same length, and for air
it's 71 kV/inch (30kV/cm) in round numbers)
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