: topband-boun...@contesting.com [mailto:topband-boun...@contesting.com]
On Behalf Of Guy Olinger K2AV
Sent: Saturday, July 28, 2012 1:06 AM
To: N2TK, Tony
Cc: topband; donov...@starpower.net
Subject: Re: Topband: Spark gaps
What is the condition of your 160m radials after the lightning strike?
Thank you to all the email's received re my use of trailer balls for a
spark gap..It is a simple answer to a big problem and it works..
It pays to think outside the box at times when presented with a problem
and be a bit innovative..
I also use a trailer ball at the bottom of the 90 foot mast a
ator of whats happening.
Carl
KM1H
- Original Message -
From:
To: "160 reflector"
Sent: Sunday, July 29, 2012 4:18 PM
Subject: Re: Topband: Spark Gaps..
> Trailer hitch balls should work fine as a lightning arrestor. Typically a
> trailer hitch ball has spherical s
shielded from rain and
insects. The gap should be adjustable, and it should be set to about the
thickness of a credit card (1 to 2 mm).
73
Frank
W3LPL
Original message
>Date: Sun, 29 Jul 2012 11:33:07 -0600
>From: DAVID CUTHBERT
>Subject: Re: Topband: Spark Gaps..
>To: R
Bob, that an excellent idea!
Dave WX7G
On Jul 28, 2012 6:06 PM, "Robert Briggs" wrote:
>
> Has anyone thought about using two trailer towing balls set up for a
> spark gap? I use this on a 90 foot insulated mast in a very lightning
> prone environmentTo date "(25)" years, with many direct h
topband-boun...@contesting.com [mailto:topband-boun...@contesting.com]
> On Behalf Of donov...@starpower.net
> Sent: Friday, July 27, 2012 5:26 PM
> To: topband
> Subject: Re: Topband: Spark gaps
>
> This link shows the base of a typical AM broadcast tower, with two hard
> steel balls used
Has anyone thought about using two trailer towing balls set up for a
spark gap? I use this on a 90 foot insulated mast in a very lightning
prone environmentTo date "(25)" years, with many direct hits, I have
sustained no damage...Mast is located 20 feet from my lounge room..
73..Bob..VK3Z
: Re: Topband: Spark gaps
What is the condition of your 160m radials after the lightning strike? 73,
Guy.
On Fri, Jul 27, 2012 at 7:48 PM, N2TK, Tony wrote:
> As a side note, last night when the storm came barreling in with very
> strong
> winds I was watching the tower as the element
Take 2 rods and grind a point on each rod. Point the points toward each other.
There is your spark gap.
You can do the dame thing with copper flat stock used on building grounds in
electrical valts.
Stay on course, fight a good fight, and keep the faith. Jim K9TF/WA9YSD
___
y the way the tower is grounded and I shunt feed it for 160M.
>
> 73,
> N2TK, Tony
>
> -Original Message-
> From: topband-boun...@contesting.com [mailto:
> topband-boun...@contesting.com]
> On Behalf Of donov...@starpower.net
> Sent: Friday, July 27, 2012 10:58 A
rpower.net
Sent: Friday, July 27, 2012 10:58 AM
To: topband
Subject: Re: Topband: Spark gaps
An air gap using one to two inch diameter balls with only a one or two
millimeter gap provides a nearly uniform field resulting in the fastest
breakdown at repeatable and fairly breakdown voltages but
I do make (all too frequent) mistakes so check away. Carbon is 2000 times
more resistive than copper. Being more resistive the carbon skin depth at
lightning frequencies is much deeper than copper or steel (note the steel
is magnetically saturated).
Dave
On Jul 27, 2012 3:26 PM, "Mike Waters" wro
o: topband
Subject: Re: Topband: Spark gaps
This link shows the base of a typical AM broadcast tower, with two hard
steel balls used as lightning protection. At kilowatt power levels its not
unusual to use a credit card to set the gap.
http://www.thebdr.net/articles/steel/twrs/LimitingStatic.pdf
73
F
Thanks, Dave. That's amazing, and I won't argue anymore, even though I
didn't (and probably won't) check your figures.
I would have thought that the carbon sphere would have a MUCH greater
resistance than .003 ohms.
73, Mike
www.w0btu.com
On Fri, Jul 27, 2012 at 3:42 PM, DAVID CUTHBERT wrote:
>
>Date: Fri, 27 Jul 2012 16:29:15 -0400
>From: "Tom W8JI"
>Subject: Re: Topband: Spark gaps
>To: "Mike Waters" , "topband"
>
>> Man, I don't know, Dave. How long have they been selling those carbon
>> balls
>> f
Mike, here it is.
The resistivity of amorphous carbon is 35 u ohm meters
(That's a 1 meter cube)
A 1" cube has a resistivity of 1.4 m ohms, a one inch sphere about 3 m ohms.
100 kA for 20 us dumps 600 J into it.
The density of carbon is 2.3 g/cm cubed
The 1 inch sphere has a mass of 20 grams
> Man, I don't know, Dave. How long have they been selling those carbon
> balls
> for that purpose?
I've never seen a carbon ball in a lightning gap application. I'd have to
see a few after being in action a long time before trusting them.
Broadcast stations use hard metallic balls, as do elect
Man, I don't know, Dave. How long have they been selling those carbon balls
for that purpose?
I don't have the figures in front of me, but carbon has a significant
amount of resistance. (Maybe that's the secret: the current gets limited as
a result. :-)
It would be interesting to calculate the re
www.rossengineeringcorp.com/toroids_spheres_corona_nuts.htm
On Jul 27, 2012 9:43 AM, "DAVID CUTHBERT" wrote:
> www.rossengineeringcorp.com/toroids_spheres_coronary_nuts.htm
>
> Ross recommends carbon for lightning.
>
> Dave WX7G
> On Jul 27, 2012 9:33 AM, "Mike Waters" wrote:
>
>> I don't thin
- Original Message -
From: "Mike Waters"
To: "topband"
Sent: Friday, July 27, 2012 11:33 AM
Subject: Re: Topband: Spark gaps
>I don't think carbon balls are suitable for lightning protection.
I agree. The last thing we want is high surface resistivity,
www.rossengineeringcorp.com/toroids_spheres_coronary_nuts.htm
Ross recommends carbon for lightning.
Dave WX7G
On Jul 27, 2012 9:33 AM, "Mike Waters" wrote:
> I don't think carbon balls are suitable for lightning protection. Think of
> the voltage drop that would appear across each ball during a
Google "carbon ball gap lightning."
Dave
On Jul 27, 2012 9:33 AM, "Mike Waters" wrote:
> I don't think carbon balls are suitable for lightning protection. Think of
> the voltage drop that would appear across each ball during a direct hit. I
> think they would vaporize.
>
> At http://www.rossengi
I don't think carbon balls are suitable for lightning protection. Think of
the voltage drop that would appear across each ball during a direct hit. I
think they would vaporize.
At http://www.rossengineeringcorp.com/hv_spark_gap.htm lightning is not one
of the applications mentioned for their carbo
You can get chrome steel balls too and they are *very* hard (usually
used for ball bearings). You have to drill them with solid carbide
drills. I don't think it would be possible to thread the holes using
normal taps though.
-Bill
[snip]
> Very hard steel balls such as carbon or tungsten are id
;Tom W8JI"
>Subject: Topband: Spark gaps
>To: "topband"
>
>Has anyone looked at, or looked for, cheap electric fence gaps??
>
>My system copper pipes near tower legs work great for me on rigid towers, I
>can bend them so they spring away from the towe
Yes a direct hit should vaporize a spark plug. For a 100 kA hit two 1"
diameter rounded steel balls may survive.
Note that Ross Engineering uses carbon balls on their spark gaps.
At 50 kA/us every inch of wire will have a voltage drop of 500 to 1000
volts, so very short wires are in order. Wide c
Has anyone looked at, or looked for, cheap electric fence gaps??
My system copper pipes near tower legs work great for me on rigid towers, I
can bend them so they spring away from the tower and then slide an inner
pipe in or out to set gap distance. I'm thinking of gaps for wire antennas.
Maybe
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