On Wed, 11 Sep 2002 Dino Darling wrote:
> Send a message to Chip @ k7ja@dxer.com He has 2 on his side yard. If I
> remember correctly, there is a small piece of channel, welded to the
length
> of the inside tube that is "keyed" to a slot in a cap that is welded to
the
> top of the outside tube.
>
> These masts are NOT water pipe! They are very thin! It amazes me that
> they even work! These engineers are really smart to get thin metal to
work
> the way they do!
>
It's the welding of the channel rib onto the water-pipe that bothers me -I'm
sure that the pipe will curl from the welding induced stresses. Also
welding will damage the galvanizing on the water-pipe, and it will cost an
arm and a leg to re-galvanize the tube after welding.
Water-pipe is thin - 4" medium galv pipe here has a wall thickness of only
0.178 ".
I've received some photographs that show a rib screwed to inner extension
tube, so those tubes must be thicker than normal waterpipe, otherwise there
wouldn't be sufficient thread length.
I'll get in touch with Chip.
Mike ZL1BNB
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