[TowerTalk] Station Ground
K8RI on Tower Talk
k8ri-tower at charter.net
Fri Jan 14 23:24:25 EST 2005
The station equipment is all on the same main, but the arc was between two
coax cables, both tied to the main grounding bulkhead.
I think I'll follow Polyphaser's recommendation on the grounding point.
It's worked so far and the tower gets hit on an average of 3 times a summer.
Roger Halstead (K8RI, EN73 & ARRL Life Member)
N833R, World's Oldest Debonair (S# CD-2)
> 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
>> 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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