I built one for a disabled friend of mine and it worked 'right out of the
box' as you might say. It required very little tweeking to get it centred
on the phone bands that he required. I know several people who have them
and they stay up and stay tuned even in what we call windy conditions. They
also have the advantage of being quiet, ie not so sensitive to local
electrical noise. It uses large twin wire in a folded dipole configuration
for each element, they are all cut to size pre-assembled ready to go with
all the stainless steel hardware. It provides low swr right across the
phone bands. We didn't fit any extra chokes: the one in the box seems to
work fine.
If I were choosing such a device, I would build the version designed by
G3TXQ, see here: http://www.karinya.net/g3txq/cobweb/ This design
significantly lighter weight. He also re-designed the HexBeam and most
suppliers now use his design, see here:
http://www.karinya.net/g3txq/wire_beams/
There are many other pages of interest on his site, in particular his
treatment of common mode chokes which I recommend to anyone:
http://www.karinya.net/g3txq/chokes/ all on one page.
David
G3UNA
----- Original billb...@nc.rr.com
>
I came across a nifty square thing called a cobweb, which is more or less
semi-flat over 4-5 bands... is very light..and can be made of pvc pipe or
possibly fiber glass because it just has 5 wires in a big square.. One
antenna to cover 20 17 15, 12 and 10 meters sounds interesting.. One of
the designs even works on 6, but has higher losses... (That may be the
baluns they use for a 4-1 impedance match and to go unbalanced...
Has anyone tried one of these critters, and if so, is the Elecraft happy
with it?
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