From: IN%"dann4gnr@hartcom.net" 16-SEP-1996 11:09:22.40
To: IN%"K7LXC@aol.com"
CC: IN%"rlboyd@CapAccess.org", IN%"towertalk@contesting.com"
Subj: Re: Lifting a lot of weight?
WELL,HERE WE GO, ME PUTTING MY 2 CENTS WORTH IN. THE REAL SERIOUS
DX'ers HAVE A SAYING, "IF IT STAYS UP, ITS NOT BIG ENOUGH". I
CONCUR WITH THAT STATEMENT. THE 48 FT. BOOM WAS NO PROBLEM FOR ME
TO GET TO THE TOP OF BILLS TOWER. THEY ARE A LOT OF EASY INNOVATIONS
ONE CAN APPLY THAT MAKES PUTTING UP HUGE ANTENNAS RATHER EASY.
HOWEVER, IT CAN BE TIME CONSUMING,FOR LIKE BILL, I MOSTLY HAVE
TO DO ALL MY TOWER WORK ALONE, OR WITH ONE OF MY KIDS DOING THE
KNOT TIEING.AT THIS PRESENT, I HAVE A SIX ELEMENT ON A 72 FT. BOOM,
SUPPORTED BY 127' OF ROHN 25. 6 YEARS AGO, I HAD A 10 ELEMENT
ON A 128 FT BOOM, SUPPORTED BY 116 FT OF ROHN 80 SERIES,A 4-FT WIDE
TOWER. I COULD HAVE EASILY MADE THAT ANTENNA 150 LONG!!! THE BOOM
CONSISTED OF 70 FT OF ROHN 25, WITH 29 FT OF COMMON 2" ALUMINUM
BOOM GOING OUT EACH END OF THE TOWER BOOM. I BUILT THE ANTENNA
ON TOP OF THE TOWER,ON PIVOTING HINGE PLATES. THESE PLATES ARE THE
REAL SECRET TO PUTTING UP A LARGE ANTENNA. THESE PLATES WERE 60"
WIDE, 15" TALL AND 1/2" THICK. BOTH PLATES FACE EACH OTHER, AND ONE
PLATE ATTACHES TO THE MAST, ONE TO THE BOOM.ABOUT 4" FROM EACH END
AND IN THE MIDDLE OF THE PLATES, I DRILLED A 1" HOLE THROUGH BOTH
PLATES FOR A 1" STUD TO GO THROUGH THE PLATES. THIS WILL ALLOW THE
PLATES TO PIVOT EITHER LEFT, OR RIGHT, DEPENDING ON WHICH STUD YOU
PULL OUT. THE OTHER KEY THING ABOUT THIS IS, THE PLATES MUST BE THICK
ENOUGH TO TOLLERATE FLEXING WHEN YOU HINGE OVER A FULLY BUILT ANTENNA.
THIS CAN BE DONE WITH ALMOST ANY ANTENNA, AND ALLOWS YOU TO BUILD
A LARGE ANTENNA ON TOP OF THE TOWER.ONE THING TO REMEMBER, THE PIVOT
HOLES MUST HAVE THE SAME DISTANCE BETWEEN THEM AS THE TOWER WIDTH,
OR THE ANTENNA WILL NOT HINGE OVER, HITTING THE TOWER BEFORE GETTING
VERTICAL. ONCE IT HINGES OVER VERTICAL, YOU HAVE 1/2 OF THE ANTENNA
NEXT TO THE TOWER. THE FINAL CRITICAL POINT IS, THE UPPER PART OF
THE SUPPORTING TOWER MUST FREE- STAND WITH NO GUY WIRES IN THE WAY
OF THE ANTENNA HINGING OVER. I ALMOST HAD A BIG PRIBLEM WITH THIS
ON THE 72 FT BOOM I HAVE UP NOW. ROHN 25 DOES NOT SAFELY FREE STAND
WITH 40FT UNGUYED, FOR 1/2 OF THE BOOM LENGTH IS 36 FT, THEREFORE
WHEN I HINGE OVER THIS ANTENNA, 36 FT COMES IN NEXT TO THE TOWER!!!
REALLY, I SHOULD HAVE PUT UP NO LESS THAN ROHN 45. I HOPE ALL THIS
HELPS SOMEONE, OR ALOT OF PEOPLE REALIZE THEY CAN PUT UP MOST ANY
THING THEY WANT AS LONG AS THE SUPPORTING TOWER HOLDS UP
73 DAN N4GNR dann4gnr@hartcom.net
Dan, those of us with round cross-section booms can rotate the boom
in the boom to mast clamp so that the elements dodge between the guy
wires so we can guy at the top of the tower. However, the REALLY
BIG problem than cannot be solved with the PVRC type mount (that is,
the tilting boom feature) is when you have another yagi on the same
mast. In this case, you may cream the elements on the other yagi while
dipping the bottom yagi. In my humble opinion, putting a second (or
third) antenna on the same mast increases the problems by more than a
factor of two (or three).
Terry Zivney, N4TZ/9
00tlzivney@bsuvc.bsu.edu
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