[TowerTalk] Ground system

[Pete Smith]

At 03:36 AM 10/27/00 GMT, Rick Bullon wrote:
>Hello All
>I am in the process of installing a tower ( been in the process for a l o n 
>g time hihi) My plan for a tower ground and shack ground are listed below. 
>All comments as to whether I am on the right track are encourage.
>For the tower ground I plan to planted 3 ground rods about 3 ft out from 
>each leg of the tower. I have about 15 or 20 ft of scrap copper tubing  that 
>was kinked at one time and had to be replaced ( this was the supply line 
>from my propane tank to the house). I plan to flatten this tubing and use it 
>for the run from each leg to the ground rods. I think this tubing is 3/4" 
>diameter (the tower will be 70' of Rohn 25). I will be using 10' ground 
>rods, should I go out another 5' and sink 3 more rods and tie all the rods 
>together or is there a better way?
>
>
>For the shack ground I have at this time  a 10 gauge copper wire running 
>from a ground rod up thru a board in the window of the shack. Each piece of 
>equipment in the shack has a ground wire that is connected to this wire by 
>way of a split copper bolt designed to connect wires together.
>I know all this is a start and probably not a decent ground system but I 
>have read thru all the archives and with so many different ways that other 
>have done this I am not sure how to improve this further
>The shack ground and the tower ground with be about 120' apart should I run 
>a wire between the two systems or leave them separate? Don't tell me to 
>connect the station ground to the utility company ground. The utility 
>company's idea of a ground is a joke. 1 6 or 8 gauge wire running the length 
>of the power pole to a thin 4" diameter copper plate nailed to the bottom of 
>the pole, no ground rod and the telephone company uses the same ground
>All the coax and control lines for the rotor and antenna switch are going to 
>be protected by PolyPhaser units although after seeing the PolyPhaser and 
>ICE units I may decide to buy ICE units they look better built to me.

When I was building my tower I bought the Polyphaser "Grounds" book and
agonized over the option of protecting every conductor from the tower into
the house.  Ultimately, I concluded that there were too many necessary
compromises in my system, particularly in the length and inductance of the
ground lead from my second-floor shack to the ground rod at the service
entrance, for me ever to be comfortable with the PP always-on approach. 

I don't believe that your grounding scheme is anywhere near adequate for
lightning protection, if all of the conductors between your tower and shack
are to remain connected.  Depending on your soil, you probably would need a
number of additional ground rods or ground radials at the base of the
tower, cadwelded to copper strap conductors clamped to the tower legs.  At
the house, you'd need a perimeter ground loop and a ground bulkhead
connected to it by a cadwelded strap, with everything, including the AC
service ground, connected to that ground reference.  All the protectors
would be mounted on that bulkhead and every conductor would pass through them.

After considering the cost and do-ability of the Polyphaser approach, I
decided instead to ground my tower base well, to disconnect every conductor
before it enters the house whenever the antennas are not in use, and to
only count on the ground in my shack to handle HF RF.  I have a big surge
protector at the AC service entrance, and smaller ones on individual
outlets, the phone and the TV cable.  After 6 years at this QTH, the only
lightning damage I have experienced is a fried modem before I surge
protected the phone line.


73, Pete Smith N4ZR

Contesting is ... Extreme Radio

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