[UK-CONTEST] ANTENNA SUPPORT

[Don Beattie]

Thanks to all who commented on my question about dipoles attached above the 
beam. There were several themes to the replies, and I'm summarising  them 
here as some asked that the responses be shared around the group.

The first and simplest approach was the "why worry" approach - a short 
length of ropeattached at the top of the mast, which had enough length 
before the dipole centrepiece to accommodate a turn of the mast.

A more sophisticated version was to use a length of thin rope. Attach one 
end right at the top of the pole and wrap around the pole in a clockwise 
direction then fed it through a pulley and back to the tower a few inches 
below the top and wrap around the pole one turn clockwise before attaching. 
The pulley should now not move as the pole is rotated. The rope unwinds and 
winds itself off/onto the top of the mast, with the puley staying in the 
same position..

Others drew my attention to the April 2009 RadCom (which I had forgotten) 
where Ian GM3SEK outlined a "bearing" approach to attaching dipoles at the 
top of rotating masts. A variant on this commented on by some involved 
dropping a second pole (very lose fit and perhaps plastic/nylon/fibreglass) 
into the top of the stub-mast, making sure it was greased so that it could 
turn inside the mast and was stopped from dropping fully into the mast by 
some sort of clamp at its top. To this clamp is attached the pulley/halyard 
for the dipole.

There was a lot of support for a non-conducting top section at the top of 
the stub-mast, to avoid the dipole conductors touching the mast as things 
move.

All in all, a great set of replies. Thanks to everyone who replied. Now - 
where's the hacksaw ?

73

Don, G3BJ