> Has anyone constructed this type of tower using aluminum?
> I am concerned
> that using aluminum might result in too much flex but it
> would certainly be
> easier to construct and erect on site. I do not intend to
> install a yagi,
> only a pulley to haul wire antennas up and down so the
> windloading should be
> Jan Rehler, W5KNZ, Corpus Christi, Texas
1. Making a mast self supporting with only its own
windloading is nontrivial, so the fact that you
are only supporting a wire doesn't help you all
2. An aluminum self supporting pipe mast would be
prohibitively expensive. You can now buy a crankup
portable mast for >$1000, but you have to crank it
down when not in use.
3. AFAIK, aluminum irrigation tubing is all thinwall,
less than .1 inch. You can make a tripod type
self supporting wire support out of this stuff by
copying the KLM SSV design by K6KBE.
4. You can of course simply put up a straight mast
made of thinwall irrigation tubing with a bunch of
ropes to guy it. This is documented on my web site
for a 90 foot design.
5. I have been using a 60 foot design (MUCH simpler
than 90 feet) consisting of 3 inch irrigation tubing
to experiment with wire antennas for the last 6 months.
It tilts up and down in 5 minutes. I have tried a
whole bunch of experimental designs. Note that instead
of pulleys, I tilt the whole mast. Far more versatile.
May or may not be compatible with your QTH; I have lots
of room to lay it down.
Hope that helps.
Rick Karlquist N6RK