> Dick:
>
> I bought my Poly's from The RF Connection (www.therfc.com ). But they
> are not made to be mounted exposed to the weather. I, like many others
> here
> on TowerTalk, mounted my Poly's in a steel box at the base of my tower.
> (I
> need Poly's at the tower base because they protect the coaxes before they
> go
> into an antenna selector switch that I also have mounted in the steel
> box.)
I can only speak for my approach, but I do not use them at the tower. The
coax shield is grounded to the tower at the top and bottom using a bracket
and bulkhead connectors. A slightly more efficient way would be to use a
more streamlined ground for each cable but the bulkhead connectors work and
are much easier to install. Then where it enters the house I use run them
through a bulkhead that is tied into the entire ground system.
>
> There are two kinds of Poly's to choose from: bulkhead mounting and
> flange mounting. I bought the bulkhead-mounting models. They are made to
Those with the flange mount attached will also work as bulkhead mounts. I
use them both ways at the house entrance.
> be mounted with the antenna-side connector poking through a hole in the
> steel box (or other mounting barrier). They include a rubber gasket to
> seal
> out the weather at this hole.
>
> The flange-mounting units are made to be bolted onto a flat surface,
> like a single-point ground panel, and allow the coax cables (antenna side
> and rig side) to simply pass over the top of the flat surface. You could
> use these inside your steel box if you also used feed-through connectors
> and
> coax jumpers in the box to get from outside to inside.
I come up into the NEMA enclosure through 3" conduit and directly to the
Polyphasers mounted to a grounded bulkhead inside the box.
>
> And you've opened up Pandora's box by asking whether you should add a
> second set of Poly's near your shack entrance. Many here on TowerTalk
> will
> say you need this second set on Poly's. I do not have a second set in my
> installation. Poly's (and other arrestors for that matter) are designed
> to
I only use the one set but find they work well at the house entrance rather
than at the tower base. Since going to this arrangement I've not had any
lightning damage or had to replace any of the Polyphasers which are easily
damaged.
73
Roger (K8RI)
> keep lightning energy off the center conductor of the coax. Once the
> tower-mounted Poly's take care of that energy, it's awfully difficult for
> more energy to get coupled onto the coax center conductors on the
> (buried?)
> run from the tower base to the shack entrance. It might happen that a
> jumbo
> lightning strike to the ground nearby might couple energy onto the shield,
> but I don't see a mechanism for that energy to get onto the center
> conductor
> for a downstream Poly to take care of for you.
>
> However, you SHOULD ground your coax cable shields at the top and
> bottom of your tower as well as at the entrance to your shack. If your
> coaxes come into the tower's steel box through the top without making any
> sharp turns to get to it, you can consider it grounded. If, however, your
> coaxes bend sharply to get into the box then you need to ground the
> shields
> before they make that horizontal turn. Lightning sees any sharps turns as
> an inductance and significant voltages could build up on the shield at
> that
> turn, blowing through the outer jacket of the coax. Grounding the shields
> once more at the shack entrance should take care of any coupled voltages
> that find their way onto the shields between the tower and the shack.
>
>
> 73 de
> Gene Smar AD3F
>
>
> ----- Original Message -----
> From: "RICHARD SOLOMON" <w1ksz@q.com>
> To: "TowerTalk" <towertalk@contesting.com>
> Sent: Thursday, November 01, 2007 1:12 PM
> Subject: [TowerTalk] Polyphaser Questions
>
>
>> Is there a distributor for Polyphaser or does one buy direct ?
>>
>> What is the best way to mount them ? I didn't find any mounting info on
>> the
>> Polyphaser website. I think a flat plate bolted to the tower legs with
>> U-Bolts ??
>> or what ?
>> The shack is about 80' from the tower. My plan is to install a set of
>> Polyphasers
>> at the tower and run the Coax and Rotor Control cable through conduit
>> under-
>> ground (12" or so). Would it add any value to have another set of
>> Polyphasers
>> at the shack entrance ?
>>
>> Thanks for any help,
>>
>> 73, Dick, W1KSZ/7
>> _______________________________________________
>>
>>
>>
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>
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>
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>
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