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Re: [TowerTalk] Water tower omni

To: Roger D Johnson <>
Subject: Re: [TowerTalk] Water tower omni
From: Ben Thorson <>
Date: Mon, 03 Jul 2006 22:25:10 -0400
List-post: <>
Roger D Johnson wrote:
> Nick Pair wrote:
>> I vote for the 4 pole folded dipole with the dipoles spaced 90 
>> deg.around a mast horizontally and phasing harness distance 
>> vertically. The commercial type where the dipoles are welded to arm 
>> on half opposite feed point. They have survived many a strike in 
>> commercial installations. You would want to use discharge devices 
>> above them on support mast and have everything well bonded together 
>> and to lightning down wire to whatever ground is present at tower 
>> base. There should be a grid if this is a community water system and 
>> access to this is important. The individual patterns on these are 
>> great enough that you get pretty good omni out of a set of four. Use 
>> factory spacing from support for best omni.
>>   Also if you can run the feed line horizontally from the support 
>> pole base through a grounded run of metal conduit just big enough to 
>> accommodate the coax will choke the large current surge down to a 
>> less than melt down level. About 20 feet will do it.
>>   That's my $.02 worth anyway,      Nick WB7PEK 
> I agree that this seems to be the simplest solution. If lightning
> takes out this array, then I'd think about the Yagis mounted
> around the tower at a lower level.
> 73, Roger
Thanks to Roger for an excellent article from Ham Radio Magazine that he 
generously scanned for me. It used three Yagis tangentially fired off of 
a large (15' on a side) triangular tower. Of course, on a water tank 
catwalk, the tank wouldn't be quite so out of the way as on a tower. One 
option would be to put something like this on the tank legs. Routing the 
cabling harness would likely be a bit more complicated since there is no 
convenient way to go between the legs. The three cables would have to be 
fed from the bottom, which would probably require some tuning to get the 
phasing correct.

Regarding the Folded Dipole solution, I had planned on putting the cable 
in a run of Rigid similar to your suggestion (EMT doesn't hold up well 
in weather). How about running it up the mast also (bonded to the mast 
of course) to say a wavelength or so under the elements? That might help 
keep the currents out of the harness also without affecting the 
radiation pattern too much???



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