Copper strap is cheaper than tubing for a given amount of surface area
verses tubing. If I had a choice of where to run that extra copper I would
run it in another direction from the tower and some from the single point
ground entrance panel, rather than in the same trench with the cables. Make
radials.
73
Gary K4FMX
> -----Original Message-----
> From: towertalk-bounces@contesting.com [mailto:towertalk-
> bounces@contesting.com] On Behalf Of jeremy-ca
> Sent: Thursday, August 16, 2007 8:45 PM
> To: Gary Schafer; wc1m@msn.com; towertalk@contesting.com
> Subject: Re: [TowerTalk] Ground System
>
> Would it help to run 1/4" copper tubing (as used for refrigerator ice
> makers) in the trench? Then bond that to several ground rods and also tape
> the coax to that tubing.
>
> Carl
> KM1H
>
>
>
> ----- Original Message -----
> From: "Gary Schafer" <garyschafer@comcast.net>
> To: <wc1m@msn.com>; <towertalk@contesting.com>
> Sent: Thursday, August 16, 2007 9:38 PM
> Subject: Re: [TowerTalk] Ground System
>
>
> >
> >
> >> -----Original Message-----
> >> From: towertalk-bounces@contesting.com [mailto:towertalk-
> >> bounces@contesting.com] On Behalf Of Dick Green WC1M
> >> Sent: Monday, August 13, 2007 10:32 PM
> >> To: 'K4SAV'; towertalk@contesting.com
> >> Subject: Re: [TowerTalk] Ground System
> >>
> >> > Coax shields won't take very much current before they melt. A large
> >> ground
> >> > wire will lower the impedance between the tower and the common point
> >> > ground, as well as reduce the voltage drop for these low frequency
> >> > components.
> >>
> >> RG-8 style coax shields won't take much current before they melt, but
> as
> >> I
> >> mentioned, I have two runs of 1-5/8" heliax running between the tower
> and
> >> shack, connected to the tower ground system at one end and the SPG at
> the
> >> other end. For those not familiar with this type of cable, the outer
> >> conductor of each run is nearly 2" in diameter -- basically a big,
> >> flexible
> >> copper pipe with a lot of surface area. I don't have a spec on the
> >> thickness
> >> of the copper, but it's probably on the order of 1/64". The resistance
> >> per
> >> foot is .14 ohm/1000 feet. I don't know the current handling capacity,
> >> but
> >> the power rating is 310 KW. Although the heliax is jacketed, and
> >> therefore
> >> won't conduct a surge to ground like a bare wire in the trench, it
> seems
> >> to
> >> me that the two large copper tubes present a much more inviting path to
> >> the
> >> SPG than the bare wire. True or false?
> >>
> >> 73, Dick WC1M
> >>
> >
> > There will be a great amount of capacitive coupling to ground provided
> by
> > those long cables even being insulated. A great deal of lightning energy
> > is
> > connected to earth by capacitance in any ground system. Yes a DC (bare
> > wire)
> > connection would be better and help more with the low frequency energy
> > coupling.
> >
> > 73
> > Gary K4FMX
> >
> >
> > _______________________________________________
> >
> >
> >
> > _______________________________________________
> > TowerTalk mailing list
> > TowerTalk@contesting.com
> > http://lists.contesting.com/mailman/listinfo/towertalk
> >
>
> _______________________________________________
>
>
>
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