On 7/8/13 9:37 AM, K8RI wrote:
On 7/8/2013 10:33 AM, Jim Lux wrote:
On 7/8/13 7:18 AM, john@kk9a.com wrote:
I also have a shack on the 2nd floor and I also disconnect all cables
going to the tower. I only use the station for major contests so doing
this is not really inconvenient. Disconnecting however is not a reliable
means of protection as the energy can be induced into anything nearby. I
am not sure if there is any way to stop this from occurring. Even if you
disconnect it is a good practice to have multiple lines of ground rods a
single point ground and MOVs or GDTs on every rotator and relay.
John KK9A
I'm not sure about the value of the multiple lines of ground rods *from
the entrance panel*. I just don't see the physics of what it's doing
there. The goal at an entrance panel is to have everything tied to one
reference voltage, and let that go up and down.
That is for operating on multiple bands to prevent the rig from rising
too far above ground Recommended by ARRL.
Exactly where is this recommended by the ARRL (so I can go find it...)
Is that the "tuned ground wire" thing? where you put half a wavelength
at each band of interest, on the assumption that a transmission line
repeats the far end impedance at every half wave.
I don't think that has any validity for lightning (and it's dubious for
Tx or Rx, as well).
What you're concerned about, presumably, is that the coax ground isn't
too different from the equipment chassis ground. That's easy: a
reasonably short wire between equipment and coax entry point.
I don't know that the voltage of the chassis, relative to some distant
point outside, has a lot of importance. After all, planes have no
ground wire or rod, get hit by lightning, and keep on working.
I think there's an enormous amount of almost correct info about
grounding out there. Some of it dates from the days of running a single
long wire against a ground rod. Some of it is from electrical codes
(which have different objectives). Some of it is just plain
misunderstanding of the physics, but has crept into the lore.
(that sharp bends have much more inductance than gentle ones... provably
wrong, but you see it in lots of places)
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