At 05:18 PM 5/28/98 -0600, Dave D'Epagnier wrote:
>
> Charles wrote:
>> I disagree with u, Dick, on two points at least:
>>
>> 1. routing coax thru PVC, I have seen two problems with this, one is
>> water sitting in the pipe if it has any horiz. parts to it, and the
>> other,
>> bigger problem, is the possibility of the PVC catching on fire in the
>> event of lightning hitting and heating up that area. The PVC that I
>> have
>> burned, burns brightly even after the heat source is gone--dangerous.
>>
>Shouldn't this be prevented from happening if a ground wire (or better
>yet, low inductance flat ground strap) is run from the tower base along
>side (and burried below) the antenna cables and is terminated at the
>ground rod outside the shack wall, which is then connected to the
>bulkhead? Doesn't the lightning surge current basically get shunted to
>ground if this arrangement is used?
>
In a word not always...even having done all of that I have had the copper
inside the RG-213 vaporised on its way to the nice ground...and it Still
made it past the protectors and into the radio house. The in house
protectors were blown off of the wall into many little pieces. This was a
comercial instalation with both portec and polyphaser protectors. Sometimes
it just makes it through no matter HOW hard you try.
>> 2. Placing the bulkhead inside the interior walls or on them
>> ("between
>> the studs") means u are placing things that will catch fire very near
>> a
>> hot spot if lightning wants to heat it. I would not take the chance.
>>
>> When lightning hit my shack one time, it lit up several cables inthe
>> window
>> sill, and I had a five inch flame burning in my lower window frame!
>>
>Did you have your entry panel grounded outside the shack to a ground
>rod?
I'll second that recommendation, and megger the ground! You would be
surprised at how often a single ground rod is NOT sufficient to provide a
good low resistance ground. Soil moisture, soluable salts, density all play
a patt and are not easily estimated simply by looking at surface conditions.
>
>> I recommend passing the coax bulkhead fittings thru (mounting them in)
>> an insulating, fireproof panel. Disconnect all incoming wires to the
>> rigs.
>> 73, K4VUD
The joys of living and working in Florida....
73's
Dave
WA4EMR
>>
> regards,
> Dave
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>
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>
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