[TowerTalk] Grounding Question

K8RI on TT k8ri-on-towertalk at tm.net
Fri Mar 25 21:35:54 PDT 2011

On 3/25/2011 10:42 PM, Gene Smar wrote:
> Roger:
>       I understand why you might think that weatherproofing a ground clamp on
> braided coax like RG-8/u might be tricky.  However, it can be done if you
> apply the proper materials.

I don't disagree with that, but I think the weatherproofing technique 
may be a bit beyond many.
In my case with a 100 foot tower and with grounding normally figured 
about every 75 feet, I think the top and bottom of the tower is close 
enough.  It's also where the pig tails tie into the coax runs at the 
top, and into the SOR2 switching at the bottom so the bulk head 
connectors should be as effective as the ones shown.
>       I posted some time back in 2001 about applying homemade ground clamps
> to my runs of RG-213 at the top and bottom of my tower:
> http://lists.contesting.com/archives//html/Towertalk/2002-07/msg00698.html
> .  You can see photos of how Joe KC2TN followed my suggestions here:
> http://lists.contesting.com/archives//html/Towertalk/2007-10/msg00356.html
> .  The trick to getting a proper seal is to use Scotch 2200 Mastic Pads to
> cover the clamp and to bridge the cut in the coax shield.
I use a Scotch mastic tape, but don't have the number handy. I also use 
flooded heat shrink which I prefer with the bulkhead connectors as it 
seals the threads and prevents moisture getting to the connectors.  
Mastic tape would need to cover the entire connector to keep water away 
from the threads.  Also the heat shrink is just a whole lot easier.

The connectors shown in the Times Wire tutorial, or instructions are 
quite easy to make, once you figure out now much sheet metal to use. A 
half inch ground rod, piece of tubing, or dowel makes a good mandrel on 
which to form the clamp. Lay the mandrel in the center of the sheet 
metal, bend it around and form it with the "duck bill" vise grips that 
are about 3 or 4" wide. Use a punch to make the holes for the bolts.  
For aluminum a gasket punch will work nicely.

I believe getting the weatherproofing done properly would be the most 
difficult for most hams.


Roger (K8RI)


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