I worked on getting my beam higher this weekend and came upon a clitch after a
whole days work getting everything prepared to go up.
I have a 22' (very strong) fiberglass push up mast to which I mounted my Ham 4
Rotor, and then mounted a 10 foot section of
galvanized steel pipe to the top of the rotor hoping to get 30 feet or so in
height out of the whole thing. The idea was to mount
the fiberglass pole to a 4 by 4 eight foot high close- line post and guy the
mast off with 5/8 inch nylon ropes.
I got it all put together including the control wire and coax to my three
element triband beam, the beam is an old Hornet tribander
(not very heavy.
After mounting the rotor to the fiber glass mast with the Rohn mast adapter I
then mounted the beam to the 10 foot galvanized 1 and
a quarter inch mast. All the cables where wire tied to the mast with enough
loop to allow the rotor full rotation and it all seemed
ready to go.
I then tied two 5/8 inch braded nylon ropes through the eyelets at the bottom
of the rotor adapter and then ran them through an
eyelet that was threaded to the top of the eight foot 4 by 4 close line post
and attached them to the back of my riding lawn mower
to use to pull the mast into the vertical position.
The mast and antenna started to lift, but there was allot of bow in the 10 foot
section of the mast that was mounted to the rotor
that held the antenna. So my son and I decided to stop and rethink it for
safety.
In case the top part of the mast holding the antenna were to snap and drop the
antenna.
So then I decided to run a third length of rope through the same points but
tying it off at the top of the metal portion of the mast
which was mounted to the top of the rotor that held the antenna.
This time my riding mower only went so far and the wheels began to spin and it
would not raise the assembly at all.
I dont know anymore how to figure fulcrum points and pulley assemblies, so can
anyone give some light on approximations for raising
a system like this, in other words what angles and measurements do you have to
have to be able to raise and lower a mast like this?
and why didn't my idea work.
73 fer nw es gud DX,
QSL VIA: LotW, BUR, e-QSL
Bob AD5VJ
http://www.ad5vj.com/
Old Calls WB5ZQU, WY5L/KH3, KE5CTY, N5IET
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