Nice pictures of a 2 wire tram system. I used a single wire tram which is
easier to rig. Raised my 52 foot boom 5el 20M with no problems. To ensure
keeping boom level I have attached PERMANENTLY 2 lengths of 1/8 inch SS wire
rope to the outer ends of the boom using eye-bolts. In normal position
these lines hang a few inches below the boom and are SECURELY fastened to
the boom-to-mast plate. For raising and lowering I attach rope to each
inner end of the 1/8 wire rope, lower rope ends to the ground, THEN remove
the lines from the mast plate. It does not take much of a pull on either to
keep antenna level. IT DOES TAKE SOME LEVELED HEADED HELPERS THOUGH.
Like KB9CRY, my boom/mast plate is about 12 x 18 inches of 6061-T6 1/2 inch
thick. I use 2 sets of HyGain mast clamps with holes enlarged to accept 3/8
inch grade 5 bolts. It has not slipped at all in 12 years of being up.
BTW, the 20M yagi is made from TELREX boom and elements (2ea 20M326 antennas
gave their life to this project) though I did use .190 thick al plates and
U-Bolts for "plumbers Delight" type of construction for element to boom.
Antenna comes in at about 170 POUNDS.
BTW, for wire rope I use cable clamps only to secure loose ends. My father
used to set chokers in the woods and taught me years ago how to braid an EYE
into wire rope. This single rule of braided eyes allowed me to erect towers
at my parents home. This is very easy to do (well not on the 3/4 to 1 inch
wire rope used in logging) and you dont have to remember the horse and
saddle riddle to get expected results.
Its winter time now so antennas that go up now work GREAT.
73 de Arne N7KA
NM
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See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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