I agree on the vaporization. The installer deliberately made the
loops, then cut off the excess coax and installed the connectors.
The dish is grounded directly via a #12 copper wire to a ~4ft
ground rod...no loops there...that's good.
Yes, interesting discussion on lightning,
73,
Charlie, N0TT
On Mon, 2 Jul 2012 12:10:03 -0500 dalej <dj2001x@comcast.net> writes:
> I suspect during a direct strike the coax would be vaporized so loops
> probably won't do much. It was a way to take care of extra coax up
> there. I always like to have a little more in case I make changes,
> which I do from time to time. If you go to my QRZ page and arrow
> down you can see the antennas and the loops. The cover page they
> aren't installed because that picture is old, like me :)
>
> I'm learning a lot with this discussion about mother nature's sparks
> and how to properly ground a tower.
>
> 73
> Dale, K9vuj
>
>
> On 02, Jul 2012, at 10:50, Missouri Guy wrote:
>
> > Hmmm...loops in coax. I always wondered why
> > the "pro" installers put loops in the coax feeds. This
> > is on my satelite internet feed. The same kind of loops
> > are on my Dish Network antenna feedlines. There's
> > one just below the dish and one fastened to the pole.
> >
> > So, is this for lightning "protection" or is it just a "service
> loop"?
> > Maybe both?
> >
> > See photo here:
> >
> http://i913.photobucket.com/albums/ac332/MissouriGuy/th_LOOPSINCOAX.jpg
> >
> > 73,
> > Charlie, N0TT
> >
> > On Mon, 2 Jul 2012 08:44:26 -0500 dalej <dj2001x@comcast.net>
> writes:
> >> I put large loops in my coax at the top of the tower. The idea
> being
> >> the lightning striking the antenna goes down the coax and won't
> make
> >> the bend so it just shoots out the coax and not down to the rig.
> I
> >> suppose it's not very effective, but I had some extra up there so
> I
> >> figured why not.
> >>
> >> Interesting discussion about lightning.
> >>
> >> 73
> >> Dale, k9vuj
> >>
> >>
> >>
> >> On 02, Jul 2012, at 8:08, Kim Elmore wrote:
> >>
> >>> No, not effective. Again, because *everything else* is in corona
>
> >> (tower legs, rivets, weld sputters, bolt threads, nut shoulders,
>
> >> joints of all kinds) and because lightning propagation isn't
> driven
> >> by small variations in the local electric field, which is all
> these
> >> devices can accomplish. Lightning begins well aloft in the cloud,
>
> >> when the e-field approaches 1 M V/m and propagates at the very
> high
> >> e-field at the tip of the stepped leader. The downward
> propagating
> >> stepped leader is typically met 100-200 m above the surface by an
>
> >> upward-propagating streamer, which is caused by the local e-field
>
> >> induced by the stepped leader. All of this happens faster (think
>
> >> relativistic speeds) than corona currents can diffuse away from
> the
> >> source.
> >>>
> >>> Kim N5OP
> >>>
> >>>
> >>>
> >>>
> >>> On Jul 1, 2012, at 23:21, "KD7JYK DM09" <kd7jyk@earthlink.net>
> >> wrote:
> >>>
> >>>> "I asked them about these corona brushes and was told that they
>
> >> are
> >>>> ineffective. Once the electric field exceeds about 50-100 kV
> per
> >> meter,
> >>>> everything -- grass, trees, fences, antennas -- are all in
> corona
> >> and the
> >>>> air is about as "saturated" with corona ionization as it can
> get.
> >> These
> >>>> corona brushes have no effect"
> >>>>
> >>>> Several of htese at a site won't lower the potential in the
> >> immediate area
> >>>> preventing charges in the 50-100 kV per meter range?
> >>>>
> >>>> I see the diasharge brushes on remote sites, radar, repeaters,
>
> >> surveillance,
> >>>> even airports surrounded by towers with brush arrays a few tens
>
> >> of feet
> >>>> across?
> >>>>
> >>>> Not effective at all? What about a row of air teminals on a
> >> house?
> >>>>
> >>>> Kurt
> >>>>
> >>> _______________________________________________
> >>> RFI mailing list
> >>> RFI@contesting.com
> >>> http://lists.contesting.com/mailman/listinfo/rfi
> >>
> >> _______________________________________________
> >> RFI mailing list
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> >>
> >>
> >
> > _______________________________________________
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>
>
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