[TowerTalk] And now for something totaly different

Dave_K9NX n7ex@athenet.net
Tue, 03 Nov 1998 07:51:12 +0000

OK gang here's a really unique problem for this creative and diverse group
to ponder and to wrestle with.

How do you turn an old concrete grain silo into a really useful vertical

Out back of the barn on this old farm I bought last year is a concrete
(steel reinforced) grain silo. The structure is 50' tall and 13' in
diameter. On top of it sits an aluminum dome about 8' tall. There are two
ladders built into it. One on the outside and another about 120 degrees
around from the first on the inside.   What I need are some creative,
practical, and relatively inexpensive ideas on how to turn this thing into
a useful vertical antenna. 

Initially I tried using it to support a 40 Meter vertical off one side and
then an 80 meter inverted L. In both cases these antennas proved to be poor
performers compared with a B'Nut vertical mounted on top of the barn. I
suspect this is because of the conductive/lossy characteristics of the silo
itself being some kind of "absorber". I currently have my 160 inverted L
hung off the thing and it too seems to be a mediocre performer compared to
other tree supported L's I have used at other QTH's but I have nothing to
compare it too at this location. 

The aluminum dome looks like a hell of a "top hat" to me but it sits on top
of the bare concrete which as was noted last month on this reflector is not
an insulator. Hypothetically I think that if I could "incase" the thing in
metal then all the RF current would be on the outside and the fact that the
lossy concrete silo is in the middle wouldn't matter it just turns into a
fat monopole. Alas I only have access to the dome at two places (the built
in ladders) and after a year of looking at it I can't figure away to
readily get to enough spots around the dome to hang a "cage" vertical
monopole off it using wires. 

Remember I said the solutions should be relatively inexpensive...........


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