I am investigating the possibility of feeding a Tower mounted beam with 450 Ohm
Ladder Line or Open Wire feeder. Assuming that I will use 9:1 Baluns (well
actually Transmission Line Transformers) at each end (ie 50 Ohm in at the Shack
end the a run of 450 Ohm feeder followed by a another 9:1 balun and 50 Ohm out)
and I can get around the Rotator issue by placing the Balun just below the
Rotator unit on a 3 or 4 foot stand off (from the Balun, around the Rotator and
to the Beam via RG213) what issues will I encounter?
I know that close proximity to the metal Tower will be a major one, so what
sort of distance awy from the Tower should the Feeder run ? Will this work ?
Has anyone done this ? What problems did you encounter ?
The shack is some 200 - 400m away from the Towers and losses at 14MHz with
RG213 and a decent SWR at the aerial of say 1.5:1 are in the Region of 7dB, or
put another way, 100 Watts in, 18 Watts at the Aerial.Open wire feeder gives
(in theory) 100 Watts in 83Watts at the aerial, over these distances.
Adrian Rees MW1LCR
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