[TowerTalk] Re: Homebrew vertical insulator and mounts DE K0FF

[K0FF]

Repost:the first one had pictures attached and didn't go through. Pictures
now linked. Geo


Here is a convenient way to use a combination of Uni-Strut, PVC pipe and
U-Bolts for mounting and insulating HF vertical antennas, this slick and
works quite well.
Uni-strut 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.
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. Uni-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 antenna 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.
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 Yagi-Uda 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.

A lightweight 40M vert (FD style) can be made from one 10 ft piece of 1"
Aluminum conduit slipped inside a 21 foot Fiberglas fishingpole, and a wire
run to the tip.

Picture of parts: http://homepages.dstream.net/K0FF/parts.jpeg


Picture of assembly: http://homepages.dstream.net/K0FF/assembled.jpeg




73 Geo, K0FF






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