Lightning Arrester Location ?
Robert11 wrote:
Hello:
Would like to get your opinions on this:
Will be putting up an Inverted-L receiving only antenna, like the PAR EF-SWL
in a few weeks.
The end point of the downward vertical leg will have a Balun, which I plan
on grounding to
a 6 foot or so 3/4 inch Cu water pipe driven into the ground at that point.
From there, I will have about a 25 foot run of coax (buried about 6 inches
deep) back to the house.
If I put the lightning arrester next to the Balun, and use the same ground
rod, will that be acceptable, or should it
really be placed right where the coax starts to enter the house ?
Would like to avoid having to drive another ground rod in, and also having
another break in the coax.
I realize that right next to the house is probably better practice for the
arrester location, but do you think it would really
matter for any induced high volt emf pulse that the antenna might be
subjected to (as the coax run will be buried) ?
B.
The antenna primary ground connection should be close to the balun,
which should also be close to the ground (earth) at the bottom of the
vertical antenna leg. My balun box is about a foot above ground. This
keeps the ground wire as short as possible to the nearby rod for good RF
grounding. The balun should be installed in a water tight box,
especially if you have a lot snow cover in your area. I used a plastic
electrical conduit junction box with a cover plate and gasket. These are
the kind made for outside use. Most good hardware stores have them. The
box came with a hole on each end for plastic conduit. I sealed these two
holes with plastic caps made for this purpose. I drilled a small hole in
the top cap and installed a brass screw from the inside, which protrudes
from the cap. This is where the vertical antenna leg wire is connected
(soldered). The bottom cap on the box has a hole for the ground wire to
exit. The wire is sealed with RTV silicone around the hole. I also
installed a female coax surface (panel) connector in another hole next
to the bottom cap for the coax lead connection. The balun is mounted on
a terminal strip inside the box where the connections are made to the
ground wire, the brass screw to the vertical antenna leg and the coax
connector. The latter should have it's ground lug connected to the
ground wire and the common side of the balun windings. The high
impedance winding (with the most turns) of the balun goes to the brass
screw on the top cap. The low impedance winding (least turns) connects
to the center terminal of the female coax connector. You can also ground
the shield of the coax near the house but I haven't found this to be
necessary. As you said, it's better to avoid another break in the coax.
Good luck.
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