[TowerTalk] NVIS Placement & Beam Separation
David Colburn
David Colburn" <whcc@freewwweb.com
Thu, 29 Jun 2000 18:12:17 -0400
NVIS QUESTION:
I am about to run a 300 foot NVIS Doublet (fed with 450 open line).
The NVIS would run at 8 feet (above grade) atop wooden fence posts.
The utility lines are about 30 feet up.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ (Electric 150ft long, 30ft high)
............................................................................
...... (CATV 150ft long, 30ft high)
--------------------------- (Phone 75ft long, 30ft high)
````````````````````````````````````````````````````````````````````
(Doublet 300ft long, 8 ft high)
Should I have any concerns about running parallel with the power and phone
lines at this spacing?
(Note: The CATV line is unused and sags some at points, the electric power
cable
sags much less.)
********************************************************************
BEAM QUESTION
If I have four tri-banders and one trapped dipole on my Rohn tower
(all fixed, not rotated) what sort of spacing can I get away with?
(Note: I have reasons for avoiding a rotor on this tower.)
Here is the planned setup:
82 feet pointing East (Force 12 C3S or C3SS)
73 feet pointing West (Force 12 C3S or C3SS)
70 feet for N & S coverage (Cushcraft C4, 40, 20, 15, 10 trapped dipole)
60 feet pointing SE (Mosley Classic)
50 feet pointing SW (Generic tribander)
(Note: I think I have read here that 9 feet of separation is OK. I just
don't know if the beams are not pointed in the same direction that makes
a difference. Also don't know if squeezing the C4 in there is OK ...
thought so if it is parallel with the tri-bander booms.)
I do not believe that I will exceed the Rohn 45 specs. It will be guyed
with Phillystran at approximately 35 and 70 feet. I will use a heavy-duty
20 foot mast that extends 12 feet out the top of the tower. That mast
will be topped with a 2/440 vertical whose base will be at 82 feet.
Sound OK to everyone?
(Note: The QTH is in Florida, just North of Tampa)
- Thanks! & 73, DavidC K1YP in Hudson, FL
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