[TowerTalk] lightening and uhf/vhf triband vertical on top of mast

Ed - K0iL k0il@mitec.net" <k0il@mitec.net
Sat, 11 Sep 1999 20:08:34 -0500


On Thursday, 09 September, 1999 1:45 AM, Ron Youvan [SMTP:ka4inm@gate.net] 
wrote:
>   I have seen fiberglass antennae that have been struck by lightning,
> y'a know y'a wouldn't think the fiber glass and epoxy could be separated 
once the epoxy sets, but they sure can.

I posted a question here earlier this year about dual band antennas.  I'd 
now like to relate an experience we just had with a Hustler G6-270 
fiberglass antenna taking a lightning strike last weekend.  When I 
purchased the G6 (and 15 others for ARES) I was concerned about lightning 
survivability, but the Hy-gain model that I really wanted wasn't available 
due to the sale of Hy-Gain to MFJ.

It was installed last month on top of a one story bldg onto a roof mounted 
tri-pod structure installed for and containing a 6 GHz microwave dish.  The 
strike completely exploded the G6's fiberglass radome into tiny shards, and 
melted and split the metal that was at the base of the fiberglass.  It 
looked like one of those exploding bullets designed to rip open whatever it 
hits.

Apparently the mounting structure wasn't properly grounded anywhere.  We 
did have a PolyPhaser installed that was grounded, but the lightning didn't 
follow the coax at all; it followed the radials out and jumped to the 6GHz 
microwave dish and down it's eliptical waveguide into the comm room where 
it destroyed a PBX switch.

I have 15 others installed on other locations, some on 100 ft towers. 
 It'll be interesting to see how many we lose next spring when Nebraska 
storms really get going.  I'm pretty sure the other towers and mounts are 
grounded properly, but I haven't seen them all.

Does anyone know of a non-fiberglass dual-bander with a better mechanical 
mount than Cushcraft's models?  Short of going to a commercial model like a 
Decibel, Sinclair, or Scala, is there anything available in dual-banders 
for amateurs that can survive lightning?  I haven't found it yet.

73,
de ed -K0iL
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           Ed Edwards    --    K0iL
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