In the May, 1984 issue of Ham Radio, Forrest Gehrke, K2BT, wrote a
final article (no. 6 of 6) on phasing verticals. If memory serves, it
was before "invention" of the hybrid coupler.
In the article, he commented that .058 wall, aluminum tubing,
telescoped, using conventional overlaps, did not withstand the rigors
of winter in the northeast. His final design used 1 1/2" OD, 1/8"
wall tubing for the first 30 feet, then 1 1/4" OD X 1/8 wall, and
then the conventional telescoping sizes of 1, 7/8, 3/4
and 5/8, .058 wall for the remaining 24 ft or so. He used 3 sets of
Nylon line guys for his design.
K2BT used machine screws for the joints, but I would be inclined to
use pop rivets and anti ox grease like those used by Force 12. Hose
clamps could be used at the top section for final adjustment.
Those who have used the "50 foot" telescoping steel masts, end up
with around 44 feet of mast. The remaining 20 ft or so of element can
be aluminum tubing, but the steel--aluminum interface will require
treatment to avoid long term corrosion problems. Of course, a single
element could be made into a T or L, which will work just as well
with a good radial system. If the element is to be part of an array,
some further thought is needed. At least one 4 square using elements
of the L configuration and another of T configuration, have been
published in the literature.
INK N4OO
Sopchoppy, FL
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