Gary, I have stopped using aluminum tubes a long time ago preferring
to use alumimum tape on fishing poles and the like
For what you are doing I recommend purchasing fibre glass poles on EBay
which are government surplus. These come in just short of 4 feet
and slide into each other.
They are about 1/8 thick walls and about 2" diameter. You can overtape these
with sticky back aluminum
tape that you can purchase at any hardwaer store. As for guys I always feel
comfortable
when I have those especially for steadying things during construction and
removal.
I think I paid about $40 for mine which was 40foot total length.
( P.S. you can scrape the tape off if you designed it to long!)
Regards
Art

"Angela & Gary" wrote in message
...
I am planning to construct a vertical dipole array for 20m. The
electrical calculations are complete (with help from LB Cebik) and now
I'm looking for some advice on the physical construction. I'd like to
use Al tubing and find unfortunately that this is difficult to come by
locally. I will likely obtain this then from Texas Towers and therefore
the tubing lengths will be limited to 6 ft each. They do offer nesting
sizes so the real question is what diameter to utilize for the lower
most 6 ft segment (dipole being some 34 ft or so). Recalling the approx
dimensions of commercial vert antennas I've had in the past leads me to
believe that 1.25" or so would be sufficient. Comments/advice ?? I
would like to do this without guys if possible and plan on attaching the
lower-most segments to 4x4's. Thanks in advance all.

Gary