About 10 years ago I bought some surplus vertical stock from the Wash DC
area. The material is 6 inch diameter aluminum, in 20 ft lengths. A 12 in.
hex face plate is welded on each end. The sections bolt together to form a
60 foot high antenna. The base 20 foot section has a single 0.5 inch pivot
plate welded on that mounts to a massive brown porcelain insulator. The
base section also has two large triangular plates welded at bottom. Many
Burndy aluminum split ring ground bolts were apparently use to affix
galvanized steel birdcage wire. I cannot determine how the wires terminated
at the top of the antenna and I did not get any material to use for the
spreaders in the center of the cage.
I was told that the antenna was part of a very large array used by a federal
agency in the DC area. I found an identifier that said Collins Radio stamped
somewhere but cannot relocate the nameplate! There must be many of these
around since the ham I bought 4 antennas (12 sections) from brought a
flatbed load back to Tennessee.
These are big boy toys. 40 feet can be bolted together and I can bounce in
the center without any permanent deflection or deformation. While I have
never erected them (since my 15-yr. old 80 meter 4 square never fell down),
they probably could be used as 60-foot towers with beams and rotors on top
or a boom for a 80 meter beam!
What do I have? I recall an article in CQ years ago about a Collins
birdcage used on 160. The well known 160 dxer was N7DF ?? who was living in
the midwest. Ideas on the origin or where to get a tech manual?
John N8UM, Oak Ridge, Tennessee
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