[RFI] Daisy-chain grounding [was DigiKeyer II]
kd7jyk at earthlink.net
Fri Dec 20 21:31:09 EST 2013
"connections on each device can create impedance "bumps" increasing overall
impedance all along the chain. Even if only two wires are connected to the
I have a 25' tower with antennas near the top. On the very top, the highest
point, is an air terminal (lightning rod). This is connected to a thick
wire, braided #2 I think, then straight line to a 3/4", 10' long copper clad
rod into the ground at the base of the tower.
Co-ax runs down the tower, clamped about every foot, then bends upward into
a junction box about five feet from the ground.
Coming out the side of this box is 2" conduit run, about 30' underground
with the co-ax to feed the equipment in the house. Along with this, from
the junction box only is a #6 braided wire, parallel with the co-ax, until
it passes the ground for the subpanel, under the house, there, the #6 ends.
This ties the co-ax on the tower, the tower and the household ground system
together. The co-ax continues another distance, feeds one radio downstairs,
then another upstairs. The ground wire does not follow the co-ax the entire
way, but the radios are connected to the household ground.
Should I bring the ground wire the whole distance with the co-ax and connect
it to the radios as well?
Another idea along this "impedance bump", what about winding the second
ground wire into a choke at the junction box to force a strike down the
direct run from the air terminal to the 10' ground rod?
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