I had put up a 1/4 wavelength 20m vertical with 1/8 wavelength
radials elevated at 7 feet, with rope guys... and the wind blew it
apart like so much tin foil!

It decided to blow it down so you could rebuild it with the proper
length radials... 1/8 radials won't work too well. Why would you
use those? They are fairly useless on an elevated ground plane.
The decoupling of the feedline will be poor, and probably lots
of rf in the shack. Needs 1/4 wave radials to work correctly.
As far as the wind, you need to build a little stouter... Normally, a
short 16 ft radiator should be easy to keep up, even with 60 mph
winds. Shouldn't fall down if it was guyed. My 40 m ground plane
was 32 ft tall, mounted at 36 ft. Nearly 70 ft tall at the top. Only
my mast was guyed. No guys were used on the radiator. I used
a telescoping metal mast which shrunk down to a very thin size
as it neared the top. Was quite flexible. In heavy storms, it would
nearly blow sideways, but it never hurt it, and it always popped
back up straight after the wind left. That particular antenna cost
nothing..Made from an old butchered up 5/8 wave CB antenna as
the base radiator, and then extended with extra tubing.
Was looking at your 2nd post, and notice the details. Not
exactly the recipe for a solid antenna...You would be better off
using an old butchered CB antenna, etc. The cushcraft AR-10
makes a good platform for verticals also. It's a 16-18 ft 1/2 wave
antenna for 10m. If you use only the radiator, and redesign the
feed, thats a decent quicky 20m 1/4 wave vertical. The old heavy duty
5/8 CB antennas are good to use also. They have heavy duty
bases that are often reinforced. Thats what I use for my tall 40m
antenna, and never had a problem, but I did strengthen by adding
extra tubing , inside the tubing. IE: double wall... Copper is pretty
soft, and shouldn't be used for anything that needs real strength.
MK

wrote:
It seems that my location boasts 60 to 110 mph winds on a regular
basis. I had put up a 1/4 wavelength 20m vertical with 1/8 wavelength
radials elevated at 7 feet, with rope guys... and the wind blew it
apart like so much tin foil!

I use 2x(2"x4"s) fastened together for a 4"x4" support and 1/4WL
wire radials as ground-plane/guy-wires. The vertical section is
assembled from 6' telescoping aluminum sections following the beam
element design guidelines in the ARRL Antenna Book. The top 8.5'
is a stainless steel CB whip. It has withstood wind gusts of about
100 mph. As others have said, copper is a poor choice for a 20m
vertical.
--
73, Cecil http://www.qsl.net/w5dxp

Actually, pure aluminium is even softer and far more ductile than
copper and is useless as a construction material.

But some grades of copper/aluminium alloy, known in the UK as
Duraluminum or just Dural, have properties approaching carbon steel
and are corrosion resistant. Light in weight. Easily machined and
extruded. Maintain a good appearance. High electrical conductivity.
More expensive than steel.

They are used, for example, for ladders and scaffold poles. When used
for tubular rigid dipoles and antenna masts they collapse under high
winds only because the wall thickness is too thin. Commonly used for
radio chassis and sheet metal roofs.

But NOT pure aluminium, just a few percent of copper.
----
Reg.


"Cecil Moore" wrote in message
. com...
wrote:
It seems that my location boasts 60 to 110 mph winds on a regular
basis. I had put up a 1/4 wavelength 20m vertical with 1/8
wavelength
radials elevated at 7 feet, with rope guys... and the wind blew it
apart like so much tin foil!

I use 2x(2"x4"s) fastened together for a 4"x4" support and 1/4WL
wire radials as ground-plane/guy-wires. The vertical section is
assembled from 6' telescoping aluminum sections following the beam
element design guidelines in the ARRL Antenna Book. The top 8.5'
is a stainless steel CB whip. It has withstood wind gusts of about
100 mph. As others have said, copper is a poor choice for a 20m
vertical.
--
73, Cecil http://www.qsl.net/w5dxp

Reg Edwards wrote:
But NOT pure aluminium, just a few percent of copper.

Next time I'll have to remember what a purist you are,
Reg. I'll specify Aluminum 6063-T832 or some such.
--
73, Cecil http://www.qsl.net/w5dxp

Visit a farm supply house and see what they have for aluminum tubing...the
stuff they use for making racks for trucks and pickups.
wrote in message
oups.com...
Hi,

It seems that my location boasts 60 to 110 mph winds on a regular
basis. I had put up a 1/4 wavelength 20m vertical with 1/8 wavelength
radials elevated at 7 feet, with rope guys... and the wind blew it
apart like so much tin foil!

Does anyone know of a decent commercial design for less than $1000 for
a free standing 30 to 40 foot support that can take this darn wind???

Thanks,

The Eternal Squire

Try these guys http://www.valcom.ca/welcome.html they make antennas for
coastal coast guard shore stations and military ship antennas I had one of
the 74 foot shore/vessal antennas it was a 74 feet high with a capasative
cap and worked like a hot dam. Mind you I got mine free for the taking at a
Canadian Coast Guard station that had replaced the antennas with something
bigger.
The Valcombs are used on board ships all over the world and on shore, I got
mine where the wind was blowing on average about the same as what you have
90% of the time, a typical shore station locations.
The one I had up weighed 700 lbs and required approx. 6 yard of cement and
it never even as much as moved when the wind blew. Sold mine to an amateur
in SD aka tornado alley and last I heard he lost his barn but the antenna
surived without even as much as a scratch.
Oh by the way it has a really low angle of radiation and worked fantastic
for DX, best antenna I've ever used, next to a rombic on the Artic Circle,
aka DEW LINE.

73...de ve7agw
Al


wrote in message
oups.com...
Hi,

It seems that my location boasts 60 to 110 mph winds on a regular
basis. I had put up a 1/4 wavelength 20m vertical with 1/8 wavelength
radials elevated at 7 feet, with rope guys... and the wind blew it
apart like so much tin foil!

Does anyone know of a decent commercial design for less than $1000 for
a free standing 30 to 40 foot support that can take this darn wind???

Thanks,

The Eternal Squire

All,

Thanks so much for getting back on this... I am located about 50 miles
west of Gallup, NM.
I am in a trailer park so I do not have a very large lot. Also while
my super is a nice person, amything large enough to seriously ding a
trailer if it fell would not be not okay with him. My wife also wants
to put a storage shed next to the trailer fairly well adjacent to where
I mounted my first pipe into concrete. That limits my choices further.

My YF is generous enough to allow me to keep trying with this antenna,
but she is already concerned that I put $300 into it ($175 parts and
concrete, $50 tools, $75 to hire someone who speaks propane torch) and
thinks that I should leave the design and installation to a
professional, hence my question about decent mounting for less than
$1000.

For purposes of discussion the dimension limits to be about 25 to 35
foot vertical, and about 8 foot radius for mounted radials. I am
allowed to create ground counterpoises up to 40 feet long as long as
they snake into the back lot. Severe sway is not allowed as it could
spank the trailer.

One thing I have noticed is that street lamps and telephone poles are
unguyed but have no problem with this wind. Unfortunately, I am not
close enough to either of them to use them for a mounting.

(I cannot move, I am committed to staying. I got laid off by my
company in mid-september and we moved to a place where my wife could
use her new master's degree in education... and we have to stay in this
trailer right next to her school as a condition of her employment... it
is, fortunately, low rent forced housing).

Questions:

1) Since I have an 8 foot limit for radials, could I have 1/4
wavelength helical radials for 40m that could fit into an 8 foot
length?

1a) Could I do the same helical trick for the radiator as well?

2) My base 1 inch diameter galvanized pipe is presently 2 1/2 foot into
a 2 1/2 foot cube concrete filled hole with 2 1/2 foot exposed. What
could I screw in it that would not need guying, and would not bend nor
sway in 100 mph wind, and how high could I make that?

3) If I run up a metal pipe to 20 foot and then an insulated wire from
the dirt to the top alongside the pipe as my radiator, what effect will
the pipe have on the radiating wire?

Thanks again,

The Eternal Squire

wrote:

3) If I run up a metal pipe to 20 foot and then an insulated wire from
the dirt to the top alongside the pipe as my radiator, what effect will
the pipe have on the radiating wire?


*Install the pipe.

*Build a 16-17 foot tapered radiator made from telescoping lengths of
6061-T6 aluminum tubing. See the Texas Towers site for the tubing.
E-mail me about doing the design of the radiator, I'm equipped to do
the FEA stress analysis.

*Build an aluminum adapter plate to attach the radiator to the pipe.
See any "how to" type ham antenna book which includes the construction
of yagis. Use a pair of stainless steel u-bolts to attach the adapter
plate to the pipe. Use a pair of insulated clamps to attach the
radiator to the adapter plate. These are available from DXengineering.

http://www.dxengineering.com/Section...&DeptID=21#Top

*Run ONE 16-17 foot wire to the the adapter plate but do not ground it.
Instead attach it the braid of the coax. Attach the radiator to the
center conductor of the coax. Pull the "radial wire" as far away from
the trailer as possible in some direction or another.

This arrangement would give you a "sorta" inverted L or vertical dipole
type antenna instead of a ground plane.

Thanks again,

The Eternal Squire

w3rv

I have one problem... I can only get stuff from Home Depot, about 50
miles away.

The Eternal Squire

On 5 Dec 2005 13:35:11 -0800, wrote:

I have one problem... I can only get stuff from Home Depot, about 50
miles away.

You received some good detailed advice, and dismiss it because it
isn't on the shelf at Home Depot (whoever they are, presumably a major
hardware chain that has squeezed competition out of the market place).

Gee, I can get stuff from DX Engineering and a whole lot of other US
based suppliers, and I am ~ 10,000 miles away.

Think positively, go find some solutions, select the best and
implement it.

Owen
--