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Re: [TowerTalk] Station grounding in a steel enclosure?

To: towertalk@contesting.com
Subject: Re: [TowerTalk] Station grounding in a steel enclosure?
From: Jim Brown <jim@audiosystemsgroup.com>
Reply-to: jim@audiosystemsgroup.com
Date: Sun, 28 Aug 2016 00:24:34 -0700
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
Trent,

Your first problem is that your box is NOT a shield if cables come through openings in the box without their shield being bonded to the box at the point where they enter. You must also bond or bypass (with feedthrough caps) all other leads coming into the enclosure, like power, control lines, audio lines, keying lines, etc. Any one of these lines that does not have its shield bonded to the enclosure or come through the enclosure via a feedthrough capacitor destroys the shielding.

As to where to put the Polyphasers -- I would use the "feed through" type and bond them to the enclosure.

The larger question is why you need a Faraday cage in the first place. Few stations do. What most stations need is proper BONDING, proper grounding, proper power, and proper interconnections between equipment. Study http://k9yc.com/GroundingAndAudio.pdf

73, Jim K9YC

For On Sat,8/27/2016 10:28 PM, trentkd5ia--- via TowerTalk wrote:
My remote station is approaching completion.  A 70' tower, wireless internet, 
solar power and RemoteRig with a TS480 is all operational.  Still in progress 
are the antennas to be mounted, and lightning protection.  I have a question 
about grounding.  The electronics are housed in a valve box--a galvanized steel 
cylinder 5 feet in diameter and 4 feet tall, with 3 1/2 feet of that in the 
ground.  A removable steel lid covers it.  All cables are in PVC pipe and enter 
the housing under ground level, and the valve box is 12 feet from the base of 
the tower.

The grounding system will consist of 9 ground rods, 3 connected to each leg of 
the tower and extending out from the tower.  The valve box will also be 
connected to the grounding system.  Polyphasers will protect against surges.

My question is, can I install the surge protectors inside the steel housing, or 
should they be mounted outside the valve box?  I'm thinking that the steel 
cylinder possibly acts as a Faraday cage, and the grounding connection and 
surge protection should be attached on the outside wall of the housing.  Any 
comments or suggestions, please?

Thanks!

Trent K5XM   on the windy and lightning prone West Texas plains

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