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Re: [TowerTalk] Station Ground

To: K8RI on Tower Talk <>
Subject: Re: [TowerTalk] Station Ground
From: Gary Schafer <>
Date: Fri, 14 Jan 2005 22:39:40 -0500
List-post: <>

To be completely properly done, the AC power should also come in through your bulkhead "ground window" with power line protectors at the ground window. It doesn't take much of an impedance difference between lines coming in to let the voltage rise very high.

If you can't get the power in through the window, the next best thing is to run the feed for all the power in the shack over to the ground window and place protectors there and then feed the shack from that point only.

Gary  K4FMX

In that case, explain this:

My cables come in through a bulkhead. Each cable goes through a PolyPhaser (bulkhead connector type) in that bulkhead. The radio station is on a large desk that sets against the West wall. To the left of that desk is a computer desk with the computer that serves as control, packet, and sometimes logging.

I had the cable to the 440 array disconnected from the Alpha-Delta coax switch for the UHF/VHF antennas. The end of the cable with the PL-259 attached was laying on the desk top, below and a bit to the side of the antenna switch for a total distance of about 10 inches. Both duo-band 144/440 rigs set on top of the hutch above the antenna switch. The switch was in the 144 MHz position.

Remember, all these cables and others go back through that grounding bulkhead.
I was at the computer keyboard on the main computer which is on a desk against the South Wall which is directly to the East of the other computer desk. Both Duobanders (the second connects to a colinear vertical side mounted low on the tower) and the 756 Pro were operating as well as all 4 computers on the Cat-5e (hard wired) network.

Lightening struck the tower and there was a briliant flash from a very bright arc accompanied by a lound "bang" from the end of that cable up to the antenna switch.

Other than Both UPSs resetting and the network reconnecting there was no indication that anything had happened.
However it's only 8 feet at most back to where the cable laying on the desk and the cable tied to the switch connect together. There was no damage to any polyphaser.

It must have been a very rapid rise time to that strike, but with all rigs bonded together externally as well as through the cables there was no damage.

Maybe that low inductance ground doesn't do anything, but after that, I will certainly continue using them in all my installations.

Roger Halstead (K8RI, EN73 & ARRL Life Member)
N833R, World's Oldest Debonair (S# CD-2)


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