Re: [TowerTalk] grounding questions

[Red <RedHaines@centurytel.net>]

Hi, Rick;

Your plan will create a better grounded station than most.  I'll offer 
one further step:  parallel the grounds to your arrestor boxes and into 
your shack, from separate points with 2 inches or more between wires and 
at least 3 wires.  This will give you the low inductance equivalent to 
using a copper strap.  Low inductance is important for grounding medium 
and high frequency energy, either lightning or RF.  Inductive reactance 
is the greater part of impedance at these frequencies.

I use 5 conductors spaced across 10 inches (they are 2.5 inches apart) 
from 5 independent but interconnected radials at the foundation, into 
the service box that holds the arrestors, where they connect to 5 lugs 
spaced across 10 inches and continue, through 5 conduits, up the wall 
and into the shack, still maintaining the 10 inch spread and are routed 
to a metal sheet behind the equipment.  Each item is grounded to that 
plate.  The reduction in reactance approaches 80%

The phone line into the computer (it's part of my station, connected to 
the HF and VHF equipment) and all power lines pass through suppressors 
that are grounded to that same plate.

It's a single point ground plate with a low inductive lead, equivalent 
to a 10 inch wide copper strap, leading to the grounding radial system.

By the way: ICE and PolyPhaser arrestors are not alike.  Each has some 
advantages.  I use ICE for my RF transmission lines because they offer a 
lower impedance path to ground for lightning energy.  PolyPhaser units 
are welded construction and less susceptible to contaminant entering 
them.  I hope they are clean when sealed.   EITHER IS FAR SUPERIOR TO A 
SIMPLE GAS TUBE!

73 de WOØW



Rick Bullon wrote:

> Hello All
> I have been though the archives and found alot of info on grounding 
> but I still have a few questions.
>
> First let me describe what I am in the process of doing right now.
> I have the ground rods in at the tower running from each tower leg ( 
> tower is Rohn 25), 1 st rod is 8' out and the other 2 are 16' apart 
> altogether 40' from the tower to the last ground rod in each 
> direction. On the ground rods running toward the shack I have the 
> ground wire running toward the trench for the coax run and then ground 
> rods every 16' to the box outside the shack.
>
> I have a metal box at the bottom of the tower and one outside the 
> window of the shack ( I know I probably only need the one at the 
> bottom of the tower but I want to be a safe as I can be as far as 
> lightning).
> Now my questions
>
> In each box are lightning arrestors( ICE units) for the coax runs and 
> the control lines. On each unit is a ground lug. Do I need to run 
> wires from each of these lugs and then attach them to the lightning 
> ground or are the units grounded though the metal boxes?
>
> If the units are grounded thought the metal boxes  then can I tie all 
> the grounds on the control lines to these lugs and free up and extra 
> terminal on the arrestors to use for the other control line coming in?
>
> These lugs don't look  big enough to use the #6 wire I using on the 
> rest on the lightning ground. What size wire is recommended?
>
> In the shack I have one #6 wire coming in that is grounded to a single 
> separate ground rod out side. This is for the equipment grounds in the 
> shack, again the ground terminals on all the equipment in the shack 
> look to small to use this big wire. I was thinking would use a split 
> copper bolt to attach smaller copper wires to this bigger wire is this 
> the correct way?
>
> One more dumb question when running the wires from the equipment 
> grounds to the ground wire coming into the the shack do I run 1 wire 
> from each piece to the main wire or connect them from 1 piece of 
> equipment to another then from the last piece of equipment to the main 
> wire?
> I think the right way is each piece of equipment to the main wire.
>
> I figure that since the ground wire coming from the tower to the shack 
> is only a few feet from the single ground wire coming into the shack 
> that I don't need to tie these together and I wrong here.
>
> And before anyone brings it up yes the ground wire is going to 
> continue to the same point that the ac and telco lines are grounded to
> Thanks and 73
> Rick
> KC5AJX
>
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See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with any questions and ask for Sherman, W2FLA.

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