[AMRadio] Valiant and Loop progress


W5OMR/Geoff w5omr at satx.rr.com
Mon Dec 5 20:31:49 EST 2005


Brett gazdzinski wrote:

>While on the subject of antennas, I wonder if anyone knows of a way
>to do what I want to do.
>I had a resonant 80 meter dipole above the house, the length was only 
>about 90 feet, so I had loading coils about 3/4 of the way out from the
>center.
>That worked ok for years, but the coax went bad at the feed point, and 
>while the antenna seemed to work ok, I had a bit of RF in the house, since 
>it was lengthwise over the entire house.
>
>I have a resonant 40 meter dipole that runs at right angles to the house, 
>and most of it is over the back yard, no RF in the house.
>
>I likely have about 90 feet there also, if I stay out of the trees.
>
>I would like to have one antenna that is resonant on 80 and 40 meters 
>without an antenna tuner, that fits in the 90 foot space.
>
>A trap dipole would be nice, but I have never found anything that holds up
>to
>AM at any but the lowest power levels.
>
>I normally run about 300 watts carrier on 40 and 600 watts carrier on 80.
>
>I made the mistake of trying one of those B+W all band folded dipoles, the
>lowest
>swr I could get about 4 to 1, maybe because of the close trees.
>They are also only good for low power on AM.
>
>The next experiment was as much wire as I could fit above the house, about
>42 
>feet each side, fed with open wire line for about 10 feet, then to coax.
>The first test showed the swr way off, so I put the antenna tuner on, and it
>
>started arcing. I added another 10 feet of coax and everything seemed to
>work ok, 
>but a lot of RF in the shack, and I bet I loose power in the coax with a
>high swr.
>
>I don't want to have to fool with an antenna tuner when changing bands, and
>would rather not use one at all.
>
>The best bet would be some sort of antenna where the 40 meter dipole is, but
>I cant think of anything that would do what I want it to do.
>
>The property is in the shape of a pizza slice, the point being my back yard.
>half way up the sides I have a medium size oak tree, and a 36 foot mast on
>the other side
>that is against the garage.
>Close to the tip of the slice, I have a real nice cedar tree that is like a
>mast,
>a very good antenna support.
>Out front, away from the crust is another medium size oak.
>The 40 meter dipole runs from that to the cedar, and is up about 40 feet.
> 
>Anyone got any ideas, other than ordering a pizza?
>

need just a little more input, Brett...

what's the length of the pizza slice, and how wide is it, at the crust?

-Geoff
W5OMR





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