On 9/21/2012 8:58 AM, Hans Hammarquist wrote:
To save some (~250 feet) of wires and cables I am thinking of hanging a steel
wire with attached cables (coax and control) between the (near) top of my tower
directly to my radio shack located on the top floor of my house. Instead I can
pull all the cables down the tower, through a ditch i the ground and up along
the side the house up to my shack, with much better possibilities of good
protection from light-strikes.
The tower is well grounded (as far as I know, 9 grounding rods, Ufer ground and
The house has a Faraday grounding cage with a total of 6 grounding spots
(plus whatever it gets through the utility connections).
The lightning protect has been tested (by direct lightning strikes) at
least twice. Burn-marks to prove it.
I am planning to let the coax cables be grounded in the tower through a plate
equipped with bulkhead connectors
and ground them at the house with a similar plate - bulkhead connectors.
That plate will be directly connected to
the lightning protection next to my shack. There are 4, thick, copper
wires that connects the lightning rods over my shack
to the grounding rods four stories down.
What I am afraid of is, in case of a lightning strike (direct hit or near-by),
the big open loop created by my overhead wires
together with the tower, the lightning protection of the house and the
ground will induce enough current to cause damages.
This loop will have an about 70 x 125 feet opening, enough to make it a
good loop antenna (not the purpose though).
125' of cable with ice just a quarter inch thick is going to be heavy.
With an inch thick it's almost unbelievably heavy.
(No I don't have any AM stations around that will have their radiation
Anyone with experience from this, or any objections? I would not like to find
my installation looking
like a fried chicken after inclined weather.
As you are in ice country (VT) I'd recommend against using a messenger
cable supporting overhead lines to the tower. It'd be convenient and
save a fair amount of money, but you'd be playing the odds.
Faraday cage? Your house or at least operating room is a copper,
bronze, or brass screen room?
In addition to the lightning problem, a little ice weighs a LOT and I
believe New England has had some big problems with ice and wet snow just
in the past few years. I've seen miles of power poles broken over out
here in the open farm country just SW of where we live now.
About 6 years ago... or so... here we had about an inch of ice. The
power line sagged right down onto the cable distribution coax and then a
tree folded over onto the whole works and those trees had lost their leaves.
Hans - N2JFS
TowerTalk mailing list
TowerTalk mailing list