[TowerTalk] Lightning Arrestors

[Marlon K. Schafer]

Polyphaser is a huge company in my industry.  They have some great info 
online.

http://www.polyphaser.com/cms_spol_app/techdocs/Lightning%20Protector%20Location.pdf

http://www.polyphaser.com/cms_spol_app/techdocs/Ligthtning%20Protection%20Facts.pdf

http://www.polyphaser.com/cms_spol_app/techdocs/Tower%20Ringing.pdf

There is a lot more available at:
http://www.polyphaser.com/technical_notes.aspx

Much of it is pretty easy reading...

laters,
marlon

----- Original Message ----- 
From: "Doug Rehman" <doug at k4ac.com>
To: <towertalk at contesting.com>
Sent: Saturday, February 28, 2009 7:33 AM
Subject: Re: [TowerTalk] Lightning Arrestors


> Let me preface this with INAE (I'm Not An Engineer...); the below is based
> on my practical experience in both public safety and amateur 
> communications.
> It is also based on the commonly seen protectors from ICE and Polyphaser.
>
> As to which is "best", there are a lot of factors to consider and what is
> "best" for one application isn't for another. I use a mix of ICE and
> Polyphasers.
>
> I have far more Polyphasers in service since new ones are often available 
> on
> eBay for a steep discount.
>
> In my previous life overseeing the communications system for a state law
> enforcement agency in Florida, I had Polyphasers installed on all of our
> feedlines (remote control phone circuits and power too). This reduced the
> summertime lightning damage from taking out a station about every other 
> week
> or so to only one or two stations per year.
>
> At least in the US, Polyphasers are used far more than any other brand in
> commercial/government VHF/UHF applications.
>
> Pay attention to the frequency and power ratings- you don't want to fire 
> the
> gas discharge tube with your RF. Also take into consideration the VSWR of
> the antenna- an unmatched antenna could cause the voltage in the protector
> to go high enough to fire the tube even though the transmitter output 
> power
> is under the rated maximum.
>
> For antennas with the potential for induced static charges (wind, 
> lightning,
> etc.), I use ICE protectors since the center conductor is at DC ground.
> Since the Polyphasers are not at DC ground, the static charge will build
> until it crosses the threshold for the gas tube to fire. In an 
> installation
> where static charge is a significant problem, the life of the protector
> could be diminished by the continual firing to dissipate the static 
> charge.
>
> If you're using anything that requires voltage on the coax (remote antenna
> switch, preamp, etc.), you'll either have to get a protector that is
> specifically designed to pass the voltage or come up with an alternate
> wiring plan.
>
> Don't forget protectors for other wires coming into the shack such as the
> rotator cable. You can find commercial products or just put MOV's across
> each line to ground. (All of the commercial protectors I have looked at 
> are
> simply using MOV's- you're paying for the nice packaging.)
>
> If you're running high power at VHF/UHF the choice of a protector may be
> very limited. My 1.2KW on 6 meters required an ICE protector- it is well
> beyond the rating of the commonly available Polyphasers.
>
> All this reminds me- I just added a 2 meter KW amp and better go check 
> what
> the max power for the protector is...
>
> Doug
> K4AC
>
>
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