In a message dated 97-11-15 10:47:19 EST, js@reallybig.com writes:
> Before any antenna
> goes up in the air, we drill out every joint and rivet them, a la Force
12!
> This is in addition to all the hose clamps, compression straps (and the
KLMs
> have many), etc. Why go through "all that trouble?"
>
> My feeling is that it is MUCH more work to first pull the antennas down
> after they are up. The rivets provide two distinct benefits. Firstly, they
> strengthen all the joints (I have never had a KLM "vibrate apart," not
even
> my 4L 40, as so many folks are wont to claim), and secondly, when I must
> take one apart for some reason, I NEVER have to worry about replicating
the
> exact dimensions again. The rivet holes do that for me.
>
> The small amount of additional preparation while on the ground saves us
> many, many more times the work if it doesn't hold up while on the tower.
>
Here's another way to do it. Since the rivets take a 2-step process
(drilling the hole and then installing the rivet) and takes a special tool
(the pop riveter), here's a one-step way to do it that I have used for years
- I use Tek screws to do the same job. They are chisel-point self-tapping
screws that you can get at most hardware stores. All you need are short ones
with a Phillips head on them and an electric drill with a Phillips drive.
They provide a nifty mechanical AND electrical bond.
I'm ignoring all discussions of how a hole weakens the aluminum element
by introducing a stress riser. If you put them on the BOTTOM of the element,
you minimize the potential problems of drilling a hole in the element.
73, Steve K7LXC
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