I'd like to ask the group memebers opinion on some vhf/uhf antenna/feedline
ideas.
For background, I've been looking to improve my antenna system. Currently, all
my vhf/uhf antennas are sitting about 4 feet about the roof ridgeline which is
about 30 feet. Each yagi is stacked about 3 feet above the other, 4 ele
50Mhz, 11 ele 144Mhz, then 14 ele 432Mhz.
I've got a nice pine tree which is about 75 feet tall and the base is about 20
feet taller than my house. The nice thing is it's cut off at the top
(topped). I've been thinkng about moving my antennas to the top of that
tree.
There seem to be a couple of issues about this:
1. Grounding - I guess this could be solved by running a nice fat ground wire
down the side of the tree and providing a few nice ground rods.
2. The distance from the tree to my shack is about 300 feet. This is a bit
more expensive to solve. From what I can tell, using LMR-400 would present
about 10.5 db loss, so 100 watts would be about 9 watts at the antenna. Even
going to something like Andrew LDF-6 would be 2.2 db loss which is almost
loosing half the output power of the xmtr. But, I'm a big fan of open wire
feeders. What about running open wire feed lines to each antenna? It's less
expensive than the hardline and in some cases, at least for the 600 ohm has
lower losses. Of course I'd have to build baluns and matching transformers on
the transmitter end, the antenna end I could adjust to be the same impedance as
the twin lead.
Any thoughts from the group on doing this? It seems like quite a bit of work
and I'm not sure how much return I would get on it.
73,
Paul (KG7HF)
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