View Single Post
  #9   Report Post  
Old July 22nd 06, 04:54 AM posted to rec.radio.amateur.antenna
Roy Lewallen Roy Lewallen is offline
external usenet poster
 
First recorded activity by RadioBanter: Jun 2006
Posts: 1,374
Default Aluminum tubing for vertical antenna

For about 20 - 25 years I've had four verticals of about 33 foot height
in my back yard. They're free standing, no guys. They went through one
wind storm with gusts in the 80 mph range, and all other weather,
without damage. Each is made of three pieces of telescoping 6061-T6
tubing, 1-1/4, 1-1/8, and 1 inch diameter. The support is an 8 foot
chain link fence line pole (about 1-1/2 inch diameter, steel), driven 4
feet into the clay ground. The antenna element is clamped to it with
muffler clamps, insulated with a couple of slices of thick wall plastic
conduit about 1/4 inch thick.

Roy Lewallen, W7EL

Hank Zoeller wrote:
Hello everyone,

I'm contemplating putting up a vertical antenna for HF use. I'm looking
at an approximate height of 30 feet or so. I am thinking of using
aluminum tubing (0.058" wall) in a 'telescoping' manner. Here are my
questions (so far):

1) Diameter. For wind resistance, should I start with something like 1
inch diameter and work down to 3/8 inch? Would the antenna be stronger
if I started with 2 inch diameter and worked down to 1-3/8 inch?

It would seem to me that the larger diameter might be better able to
withstand wind but it would also offer more resistance to wind possibly
negating the additional strength. But, I have no experience to draw
from. So, fat or slim?

2) I am planning a set of guy ropes at about the 12 foot level, a bit
over 1/3 height. Is there a better height for guy ropes? I can put as
much concrete in the ground as I like, and a very robust mount system is
possible. Is there any way to make an unguyed 30 footer that isn't a
tower form factor? Something like making the bottom 12 feet or so from
2 inch diameter, 1/4 inch wall tubing and then light weight tubing from
there up to full height?