Daniel,
I built solid 40m verticals with relatively inexpensive aluminum tubing from
Texas Towers. I started at 2.125" at the bottom and I think they telescoped
to 1.25" at the top. There was 1 guy level at 15'; I used the small
Phyllistran for the guys.
Compared to commercial verticals I've had (HF2V, HF6V, R6000), the 40m
verticals I built were rock solid. There was hardly any flexing in wind
that would have the others bending sideways (and the Butternuts were guyed
as well, about 8' off the ground, and the whole top would bend in the wind
at the guy point). And, it cost me less to build one of those than any of
the commercial ones.
I also have 2 full-size 80m verticals up. They are also made with tubing
from Texas Towers. They are 66' tall and start with 2.125" at the base. It
is done with all 6' UPS-shippable pieces, but the first several sizes are
doubled up. Once it hits around 1.625" they are just 6' lengths. The top
piece is 1.25".
They are guyed with 5 levels of Phyillstran. Basically, they are guyed
every 11' up the vertical. The guys are 40' out at the top of 4' posts
(effectively making them out about 43', but more importantly making it
easier to get the lawn mower around the guy areas).
Raising 66' verticals made with that kind of tubing requires a trick or two.
My first round with this array didn't last too long because it only had 2
guy levels 28' out (that taught me to go cheap on the Phyillistran!) To put
those up, I took each vertical in 2 pieces (top half and bottom half) and
leaned it up against my tower (in the center of the array). I climbed to
the top of the tubing, lifted the top half up, and completed the vertical.
I tied off the guys, then I had to move it 35' away. I did that about 6" at
a time, each time loosening and tightening the guys as needed. That process
took about 6 hours for each vertical.
When it came time for round 2, I decided I wasn't doing that again. So, I
found a local sign company that had a 55' bucket truck (well, a ladder truck
with a bucket on the end of the ladder). That made the assembly much
easier.
Here are some pictures:
Vertical (only top 4 guy levels visible):
http://www.klient.com/80mVertical.jpg
Anchor: http://www.klient.com/80mAnchor.jpg
Assembly: http://www.klient.com/80mAssembly.jpg
If I had to do it all from scratch I might go with 25G for the lower 50' of
the 80m verticals. But, for the most part, I was re-using parts I had from
previous antenna projects so that affected my decisions. But, this design
seems pretty solid thus far.
As far as the matching network goes, as others have said... you shouldn't
need it with some radials under the vertical(s). The impedance will be
around 80 ohms with no radials, going down to around 36 ohms with a decent
radial system. There's no problem feeding that directly with 50 ohm coax,
although if you were really concerned about it you could make a hairpin
matching coil out of 1/4" copper "refrigerator" tubing. Just a few turns 3
or 4" diameter would do it and you can stretch/compress the coil to give a
perfect match.
73,
Tom, NI1N
----- Original Message -----
From: "Daniel Hileman" <n9wx_dan@yahoo.com>
To: <towertalk@contesting.com>
Sent: Sunday, May 15, 2005 7:39 PM
Subject: [TowerTalk] Monoband Verticals
> Hi Everyone,
> I am looking for a manufacturer of Monoband 1/4 wave
> verticals, I've heard of Gladiator but can't get their
> website to work, so thinking they might be out of
> business. I might homebrew one, I'm looking for
> suggestions and ideas on building a 1/4 for 40 and
> 80m.
> I'm thinking of 1" copper tubing on the 40m and 5"
> irrigation tubing on the 80m one. Anyone know about
> what price to expect for 3-5" irrigation tubing per
> foot?
> Also, is a matching network needed for 1/4 wave verts?
>
>
> Thanks,
>
> Daniel N9WX
>
> __________________________________________________
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_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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