Try an industrial surplus/scrap type place. When I was looking for
stuff at our local one in ABQ they had just about everthing you can
think of piled somewhere. I bought some railroad rail (big) at $2 /
foot 1800 lbs of steel for $120 bucks!
NN5K
JC Smith wrote:
>Greetings fellow TTs:
>
>As my new tower gets closer to going up (still have to clean out the bottom
>corners of the foundation hole, but it's been over 100 deg. F here lately) I
>am thinking of my old tower's (UST MA-550MDP) nice circular foundation. It
>is in the front of the house and in an ideal location for a flagpole. I've
>been looking at the streetlight poles the city uses. They are
>tubular/tapered, starting at about 4" diameter at the bottom to maybe 2" at
>the top. They have a four-bolt mounting pattern almost identical to the
>MA-550's rotor base. They look like they would make a great flagpole and a
>lighted one at that. Any idea where I could find one of those critters?
>You must buy in large quantity from the manufacturers, so that doesn't work.
>I've tried calling the city to see if they have surplus. No luck. I'll try
>some other local cities and the county, but maybe someone on here has an
>idea? I'm looking for something in the 30' range.
>
>Thanks & 73 - JC, K0HPS
>
>
>-----Original Message-----
>From: towertalk-bounces@contesting.com
>[mailto:towertalk-bounces@contesting.com]On Behalf Of Bill Aycock
>Sent: Wednesday, July 19, 2006 2:00 PM
>To: Nick Pair; Towertalk@contesting.com
>Subject: Re: [TowerTalk] braid and high current
>
>
>Pardon me, but this is the biggest collection of garbage on this subject
>that I have seen. The braided copper conductors I have seen in explosives
>storage were about 1/2 inch in diameter, and were braided to allow limited
>flexing on installation. The individual wires were at least #12, and more
>likely (from appearance) #10. Also, Army Ordnance, at least, thought they
>were there for lightning grounding and dissipation, not just to calm the
>fears of the peasants. Next time, get some facts before expounding .
>Bill-W4BSG
>
>At 11:17 AM 7/19/2006 -0700, you wrote:
>
>
>
>>Hello all,
>>
>> The first problem with braid is that the stuff forms a coating of
>>copper oxide around each strand that is nonconductive. This coating makes
>>each wire like a individual conductor with a resistance according to its
>>gage. Now think of the flexing due to vibration, heat cycling, or any
>>other thing which will cause the strands to rub against each other thus
>>breaking the copper oxide surface. The crossover points of the braid will
>>be alternatively be conducting and then reoxidizing to nonconducting
>>state. This makes all the strands at different resistances which when the
>>20,000 to 200,000 amp surge hits them will cause some of them to take
>>more of the current than others and vaporize. An avalanche effect occurs
>>and you have meltdown and arcs.
>> Second we have the idea that all the current will travel on surface
>>with the skin effect. This is true for normal current amounts but at the
>>current levels of lightning there are not enough free electrons at
>>accommodate the current flow and the conductor depth comes into account.
>>If not enough depth is available the current has to flow outside of the
>>conductor in a arc as there is no where for all those electrons to go.
>>
>> The use of braided strapping to protect ammunition was to prevent a
>>static discharge from detonating the charges not the high current of
>>lightning. In the workers minds they thought it was for lightning but all
>>you can do with lightning is shunt the current, not stop flow. Even if
>>you shunt 99% of current there is enough voltage to arc at even micro
>>amps which is enough to make fireworks out of your munitions. The only
>>safe place was inside of conductive box with lid closed. (i.e. ammo
>>boxes, metal lined bunkers, etc.)
>>
>> That leaves us with either large stranded (each strand #12 or
>>larger) or solid conductors. Even solid has enough flex to allow a
>>fold-over to work if you disconnect(or never use ) the ground opposite
>>the hinge.
>>
>> Save your braid for your indoor station ground applications.
>>
>> 73
>> Nick
>> WB7PEK
>>
>>
>>---------------------------------
>>How low will we go? Check out Yahoo! Messenger's low PC-to-Phone call
>>
>>
>rates.
>
>
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>>
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>>
>>
>
>Bill Aycock - W4BSG
>Woodville, Alabama
>
>
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