K1TTT wrote:
>> K1TTT wrote:
>>
>>> There will always be a potential difference between them during a
>>>
>> lightning
>>
>>> stroke, you can't prevent that. The concept of a spg is to protect
>>> equipment in a building. All the wires coming in through the spg are
>>> connected together so they are all at the same potential so there should
>>>
>> be
>>
>>> no chance for arcing and sparking inside the building.
>>>
>>>
>> Even that only sota, kinda, almost works. All of my cables come in
>> through a bulkhead. The coax cable shields are grounded at the base of
>> the tower AND they are grounded at the bulkhead along with the other
>> coax cables, rotator cables, remote antenna switch cables, where they
>> come in the house. I've mentioned this before, but two of the cables are
>> from the 144 and 440 arrays. Both have pigtails that run from the
>> bulkhead to the antenna selector switch. I had one of them disconnected
>> and laying on the desk about 8" to 10" from the switch. Lightning hit
>> the tower and there was a tremendous flash from the coax laying on the
>> desk to the selector switch. Yet both cables are the same length and run
>> to the same grounding bulkhead. Why the flash-over? It sounded like
>> some one fired a 12 gage here in the den. BTW both antennas are at DC
>> ground.
>>
>
>
> How long are the jumpers from the bulkhead to the switch?
About 8'
> Could you tell
> where the arc initiated on the coax,
From the shell of the disconnected PL-259 to the frame of the Alpha
Delta coax switch....which also ties to that same grounded bulkhead
> the connector shell or the center
> conductor??
>
>
It almost had to be the shell as the Polyphaser was OK.
73
Roger (K8RI)
>
> David Robbins K1TTT
> e-mail: mailto:k1ttt@arrl.net
> web: http://www.k1ttt.net
> AR-Cluster node: 145.69MHz or telnet://dxc.k1ttt.net
>
>
>
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