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Author Topic: need something better than a dipole for qrp/p  (Read 934 times)
VE3RRQ
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Posts: 21




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« on: August 18, 2003, 11:49:20 PM »

I have a dx77 vertical for bands between 10-40m...hears great but gets out on 1 watt or less ok but not consistent with this summers band conditions...I was thinking of putting up a wire quad built for 17m or 20m hung from trees.I have room for 3 or 4 elements but require reflector formula and spacing ideas between reflector driver and director/s...Another question should I feed it with 300ohm twin or 450ohm ladder?...Thanks mike ve3rrq
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W3JJH
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Posts: 1421


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« Reply #1 on: August 19, 2003, 04:07:54 PM »

There's an on line Javascript quad antenna calculator at

http://www.softcom.net/users/kd6dks/quad.html

It comes up with designs to be fed with 50-ohm coax and a 1;1 balun.
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WB6BYU
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Posts: 13578




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« Reply #2 on: August 19, 2003, 05:03:54 PM »

Of course the quad will only be directional on one
band - or it might point different ways on 20 and 17m,
depending on the tuning of the parasitic elements.

For multi-band use (at least over a 2 : 1 range or so)
a single wire loop should work, and it can be fed with
either 300 or 450 ohm line.  For multi-band gain I'd
try something like a lazy-H or some sort of curtain.

But, to answer your question, there are "standard"
formulas for quad dimensions, and they may work to
some extent, but design is really a lot more complicated.
I recommend the quad design series at www.cebik.com
(for example, "new quad studies".)   This includes a
set of basic programs to calculate optimized dimensions
based on the desired frequency and wire size.
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N6AJR
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Posts: 9927




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« Reply #3 on: September 12, 2003, 09:54:46 PM »

put up a Fan Dipole, do a search here on the Elmers Search and you will find a bunch.  Basically it is a set of dipoles for what ever freq's you want fed with a common coax.  the resonant dipole shows a 50-ish ohm impedeance and the rest show a high Z so the majority of the signal goes out the resonant antenna.  you can make one from 160 meters to 440 mhz all on one fan antenna, but usually they are made for 80=10.  they work , are cheep and easy to build.
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K8AG
Member

Posts: 352




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« Reply #4 on: February 17, 2004, 04:52:51 PM »

Wire quads are directional and may require considerable maintenance to keep them up.  I have a ZS6BKW (which is an SWR optimized version of a G5RV).  It seems to do really well on QRPp receive and I have done 2200 mile sper watt with a Pixie II at abour 115mw.  It is up about 40 ft and really rugged.  You might consider one of these in addition to the quad, especially if you live in an area with significant weather.

73

JP, K8AG
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