[TowerTalk] Homebrew vertical insulatore and mounts DE K0FF

[K0FF]

To answer Bruce's question concerning making ground mounted HF Vertical
antennas from common, readily available components:

Yes Bruce. I use a combination of Uni-Strut, PVC pipe and U-Bolts for this
and it is very slick and works quite well.
Unistrut is  available at Home Depot etc. It is a 3 sided square metal
bracket with a series of holes in the back wall, and come is 10 ft. lengths.
The front  is open, and the sides are rolled over into the opening creating
a remarkably strong structure. In it's intended role, it is secured to a
wall or ceiling, and special clamps are inserted into the open side, and
conduit hangers are attached with bolts. Once I happened across a dumpster
on a construction site that had dozens of 2 foot cutoffs in it. These found
a welcome home in my boneyard.
A piece of this maybe 18 inches long serves as the adapter between the steel
pipe in the ground, and the PVC insulated vertical antenna. Un-Strut or
sometimes called B-Line comes in several sizes, the 1-1/2 by 3/4 is OK for
small stuff, but I use the more common 1-5/8 x 1-5/8 size for it's added
strength.

 Find a piece of PVC pipe about a foot long and a sloppy fit over your
bottom aluminum tube. Slit the PVC pipe all the way down one side with a
saber saw, and make a second cut a fraction of an inch away,  to widen the
gap  so that when you clamp it around the aluminum tube, the gap almost but
not quite closes. 1-1/4" Schedule 40 PVC pipe is the perfect size for the
RadioShack 5' TV mast sections. Various plastic plumbing tubes and pipe can
be had in PVC, Poly, and ABS. All seem to be good insulators at RF,
especially at the voltage node.

Drive a steel pipe section into the ground a few feet (use a posthole digger
and concrete for a permanent installation), and leave 2 feet sticking up.
Clamp the bottom half of the Unitsrut to the steel pipe with 2 s.s. Ubolts,
made for 1-1/4 inch water pipe(a standard hardware store item). The round
part goes around the steel pipe and on the backside of the Unistrut put the
supplied flat backup plate and nuts.
Then do the same on the PVC covered antenna section with 2 more s.s. Ubolts.

This arrangement will automatically set everything straight in-line, as the
round pipe parts seat into the open face of the Unistrut, and when clamped,
everything lines up automatically.


I developed this method when installing my first Butternut antenna, which
had only a pipe out the bottom with no kind of mount whatsoever, or even
tips an making one in the manual! DUHH!
It would up being so useful that I use the same concept on any number of
antennas now, including when I mount something on the mast top on the tower
or making sidearms....
This trick of slitting the 1-1/4 in PVC makes a great adapter for using
RadioShack masts inside a Ham M or HD73 Rotor, as the clamps won't go that
small otherwise. Some Yagi0Uda antenna clamps are too big for R/S TV masting
and need spacers too (my portable-mobile is based on the R/s masts).
As far as the radiating element tubing, that a topic all by itself, and a
great deal depends on the height, weather conditions, bands in use etc.

73 Geo, K0FF

When I get a digital camera, I'll make photos available.
-----Original Message-----
From: Bruce Sawyer <n6nt@ynn.com>
To: TOWERTALK@contesting.com <TOWERTALK@contesting.com>
Date: Friday, June 23, 2000 10:05 AM
Subject: [TowerTalk] Homebrewing Verticals


>
>I'm curious if anybody on the reflector has found any readily-available and
>easy-to-use material to function as the insulator between the base section
>of a vertical and the active element for it.  I've looked at all kinds of
>combinations of PVC water pipe, ABS pipe, PVC electrical conduit, etc., but
>the standard sizes for aluminum tubing and for pipe materials simply don't
>correspond the way we would require in order to use the pipe as an
>insulator.  What we need, of course, is some kind of insulating pipe and
two
>sizes of aluminum tubing such that the insulating pipe will just barely fit
>inside the larger piece of aluminum tubing and such that the smaller piece
>of aluminum tubing will just barely fit inside the insulating pipe.
>However, I'm sure there could be something in all the bins at my local Home
>Depot that I've missed (e.g. a PVC coupling fitting).  Has anybody here
>found a good solution for this?
>
>Bruce, N6NT
>
>
>--
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>


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