[TowerTalk] [Fwd: Re: LOW INDUCTANCE COPPER GROUNDING STRAP]

[ChetMoore]

After watching a similar discussion on using braid for grounding equipment 
and right after I had just  just finished grounding every piece of equipment 
with copper braid.  W3LPL  jumped in with the IEEE reference and a one 
sentence summary that I think went like this.........


BRAID................... IS SOMETHING THAT LITTLE GIRLS DO TO THEIR HAIR.


That statement cleared up any lingering doubts I had about using braid. 
Continue to use braid at your own peril.

Press on regardless

73

Chet N6ZO


----- Original Message ----- 
From: "K8RI on Tower talk" <k8ri-tower at charter.net>
To: "Tom Rauch" <w8ji at contesting.com>; <Cqtestk4xs at aol.com>; 
<TOWERTALK at contesting.com>
Sent: Monday, October 10, 2005 3:28 PM
Subject: Re: [TowerTalk] [Fwd: Re: LOW INDUCTANCE COPPER GROUNDING STRAP]


>I remember having to replace the coax inside a number of amps back then. 
>One
> end of the braid would overheat to discoloration and melt the dielectric
> which of course shorted the coax.  *IF* I remember correctly this was the
> lead that went to the transfer relay and was a common problem with that
> particular amp.  I've even forgotten the model now, but I sure fixed a 
> bunch
> of them.
>
> Roger Halstead (K8RI and ARRL 40 year Life Member)
> N833R - World's oldest Debonair CD-2
> www.rogerhalstead.com
>
>
>>> I think W8JI posted on this one a while back, and if my
>> memory serves me
>>> correctly, the reason braid is inferior is that as it
>> corrodes it increases
>>> resistance.
>>
>> Skin effect forces current to the outside surface. Since the
>> outside weaves into the inside, current has to flow through
>> the hundreds and hundreds of pressure connections. The
>> connections are bad enough when the braid is fresh and shiny
>> and has pressure forcing the strands together. They are
>> terrible when the braid becomes tarnished or the pressure
>> lightens up.
>>
>> As a matter of fact this is one of the main reasons coaxial
>> cable goes "bad" and has high loss after moisture gets
>> inside.
>>
>> When testing HF amplifiers in the 70's or 80's we found the
>> braid removed from RG8 coax had more loss than number 14 or
>> 16 wire in ten meter tank circuit leads. Despite being
>> larger (meaning it would dissipate more heat) the braid
>> overheated to the point of discoloration while #16 wire with
>> much smaller surface area remained shiny.
>>
>> 73 Tom
>>
>>
>>
>>
>>
>>
>> _______________________________________________
>>
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> _______________________________________________
>
> See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless 
> Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with 
> any questions and ask for Sherman, W2FLA.
>
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