Drip loop is a better name for them, although I didn't loop for that reason,
the tower is a ways away from the house. I do have drip loops in the dish coax
which enters the house directly from the dish antenna. In my case I guess they
would be a service loop incase I need the extra coax.
My tower ground is a series of 3 rods outside the concrete base and they are
all connected together to form a ring using the heavy solid copper wire that's
used for service grounds to main breaker box, my remote antenna switch is also
bonded to that ground system. I also have a run of that same wire which
connects to my station ground and goes under the turf to the tower ground.
It's about a 30 foot run or so. I hope it will be ok and I hope it will never
be needed.
73
Dale k9vuj
On 02, Jul 2012, at 12:48, Roger (K8RI) wrote:
> On 7/2/2012 9:44 AM, dalej wrote:
>> I put large loops in my coax at the top of the tower. The idea being the
>> lightning striking the antenna goes down the coax and won't make the bend so
>> it just shoots out the coax and not down to the rig. I suppose it's not
>> very effective, but I had some extra up there so I figured why not.
>
> I call those drip loops to keep water/moisture out of the coax.
> I ground the coax shield at both the top and bottom of the tower so I
> don't worry about the lightning having to jump anywhere and my system
> has taken many direct strikes. Most of those strikes do nothing, but I
> have had a couple that removed the plating (and weatherproofing) from
> every connector up there and with 6 antennas that is a lot of
> connectors. 17 if I counted correctly with power dividers and rotator
> loops. They were just bare brass (with a very rough finish). The
> weatherproofing which was the self sealing tape covered with regular
> Scotch 66 tape looked like sheets of expanded metal.
> That was when I realized the fallacy in believing a good job of weather
> proofing will always keep water out of the coax.
>
> 73
>
> Roger (K8R)
>
>
>>
>> Interesting discussion about lightning.
>>
>> 73
>> Dale, k9vuj
>>
>>
>>
>> On 02, Jul 2012, at 8:08, Kim Elmore wrote:
>>
>>> No, not effective. Again, because *everything else* is in corona (tower
>>> legs, rivets, weld sputters, bolt threads, nut shoulders, joints of all
>>> kinds) and because lightning propagation isn't driven by small variations
>>> in the local electric field, which is all these devices can accomplish.
>>> Lightning begins well aloft in the cloud, when the e-field approaches 1 M
>>> V/m and propagates at the very high e-field at the tip of the stepped
>>> leader. The downward propagating stepped leader is typically met 100-200 m
>>> above the surface by an upward-propagating streamer, which is caused by the
>>> local e-field induced by the stepped leader. All of this happens faster
>>> (think relativistic speeds) than corona currents can diffuse away from the
>>> source.
>>>
>>> Kim N5OP
>>>
>>>
>>>
>>>
>>> On Jul 1, 2012, at 23:21, "KD7JYK DM09" <kd7jyk@earthlink.net> wrote:
>>>
>>>> "I asked them about these corona brushes and was told that they are
>>>> ineffective. Once the electric field exceeds about 50-100 kV per meter,
>>>> everything -- grass, trees, fences, antennas -- are all in corona and the
>>>> air is about as "saturated" with corona ionization as it can get. These
>>>> corona brushes have no effect"
>>>>
>>>> Several of htese at a site won't lower the potential in the immediate area
>>>> preventing charges in the 50-100 kV per meter range?
>>>>
>>>> I see the diasharge brushes on remote sites, radar, repeaters,
>>>> surveillance,
>>>> even airports surrounded by towers with brush arrays a few tens of feet
>>>> across?
>>>>
>>>> Not effective at all? What about a row of air teminals on a house?
>>>>
>>>> Kurt
>>>>
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