Did you consider the Polyphaser grounding kits? AFAICS from the
literature, you strip off the outer jacket, clamp one end of the copper
strip around the exposed braid, then seal the whole thing up and connect
the other end to the tower. This would eliminate the additional
connectors with their possible impedance bumps.
There are several versions of the kit. AFAICS (again -- I've not used
their kits), the copper strip is plated with some suitable metal so as
not to result in corrosion of the metal to which it is connected at each
end -- copper, galvanized, tinned, etc.
Has anybody used these? How successfully?
73
Alan NV8A
On 06/26/06 10:02 pm K8RI on Tower talk wrote:
> Due to basement work I've had to pull all the cables out of the conduit.
> Man, but I was sore the other day and was wondering whey until I realized
> I'd pulled between 1300 and 1500 feet of cable out of conduit the previous
> evening.
>
> This has put me off-the-air with the main station which is probably why
> 6-meters has been open the last couple of weeks.
>
> As this is turning into a rotator repair (It's hanging up again and the
> thrust bearings are free), antenna repair, antenna removal, replace the pig
> tails, and reroute the coax project I've decided that as long as the coax
> has to go through connectors at the end of the pigtails at the top of the
> tower I'm going to mount an aluminum angle across the face of the tower with
> 3" UHF feed throughs. Each of the current 4 pig-tails will fasten to a feed
> through which will ground the brade to the tower at the top. The cables then
> run down the inside of the NE tower leg where they are joined by two more to
> the base and loop up into the junction box where they enter the 3" conduit
> to the house. The cables will be jointed by at least one or two more part
> way down the tower, but there may be two less from the top. The easiest is
> to just say the number may vary.
>
> My thoughts are to either use another set of bulk head connectors on
> Aluminum angle bracketed to the tower as at the top, or to clamp those
> brackets to the leg of the tower using a hose clamp and spacers so the
> center part of the feed through will be grounded to the tower leg.
>
> This will add one more set of connectors to the cables but from experience
> and information gleaned from TT I'd say the insertion loss of the one extra
> connector is going to be almost non existent. In addition the cables will be
> grounded to the tower where they are leaving the tower.
>
> The new junction box at the house entrance will be putting the shield
> grounds and the Polyphasors (sp?) right outside the house at the point of
> entry where they are currently just inside the house. I think this will be
> an bit of an added safety feature.
>
> One leg of the tower ground system will be entering the Hoffman box beside
> the conduit, grounding the back plate inside and then continuing into the
> house with the other cables. This #2 runs directly through to the house
> ground for the electrical service as it's the only way I can get it there.
> I'd have to tear up a rather expensive garage apron to get there outside and
> that would make the grounds different length.
>
> This is going to get rid of the conduit coming through the basement wall.
> It'll come in through the end plate of the floor joists and there will be no
> cables showing below the basement ceiling. At least that is the plan.
>
> Remember it's normal for this installation to take at least three lightning
> hits a year and I think it's already had it three (or more) just in the last
> storm.
>
> Any socially acceptable suggestions?
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