[TowerTalk] Re: TowerTalk Digest, Vol 11, Issue 56

[kb9cry at comcast.net]

I also believe both the PolyPhaser and ICE website technical articles warn against non metallic towers.  I don't recall their exact reasoning but I believe it's along similar lines as stated.  If you're going non metallic because of severe corrosion, there are other methods that can be used to reduce that effect, i.e. special coatings, sacrificial anodes, etc.  Phil  KB9CRY
> At 12:01 PM 11/20/03 -0500, Bill Fuqua wrote:
> >What is so great about nonmetallic towers?
> >I seem to be missing something here.  They will not stop lightning and I 
> >suspect that if they are hit.
> >And strong electric fields develop across any of the nonmetallic members 
> >the material may just
> >explode due to the internal stresses in the "dielectric" bonding material.
> >I can see lighting hitting the antenna and going down the feed-line and 
> >damaging the tower along the
> >way.   Do they mention the dielectric strength of the tower or resistance. 
> >Is it non-conductive?
> 
> 
> I note that in the installation instruction book they mention that "proper 
> precautions" must be taken against lightning to avoid severe damage to the 
> antennas or the tower.  Sounds like confirmation of this concern.
> 
> I'm also not sure whether a tower made of this stuff would appear to be a 
> conductor in the field of the antennas or not.  I do recall that when 

> carbon-carbon was first considered for aircraft components one concern that 
> had to be worked through was whether the debris in the event of a crash 
> would cause disruption to nearby electrical circuits through conductive 
> fallout.  I think the US also has some bombs that are designed to kill 
> electrical distribution systems through scattering conductive carbon fibers 
> across switch and transformer yards.
> 
> 
> 73, Pete N4ZR
> The World HF Contest Station Database was updated October 29.
> 2469 stations are listed -- 29 new and over 100 updated.
> Are you current? www.pvrc.org/wcsd/wcsdsearch.htm
> 
> 
> 
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> 
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