[Antennas] Cubical Quad Question

[Tom]

Hi Randy,

I have a 6 band one also on the Gem Quad spreader / spyders and 
according to L.B. Cebik the best thisg to do is to feed each loop 
independently with 1/4 wl electrical piece of coax.  However the trick 
is to also disconnect the braid as well as the center conductor when the 
band is not isn't use.

This minimizes interaction by electrically opening the loop.  Mine show 
little interaction issues though 10 / 12 are still very close in 
frequency and I did need to adjust them once they were up.  But is is 
doable and I do get good bandwidths from each.

John, EI7BA has some lengths on his web site that I started with and 
almost all remained the exact length.  6 meters and 10 had to be 
adjusted a bit.  1005 is not even close on those bands...

Good luck and enjoy the Quad!  Great antenna!

73, Tom W1TJL

-- 
Tom LeClerc, Amateur Radio Station W1TJL
   (past calls WB1CBY, /VE8,XL8,CI8,VO2)
     Yankee Clipper Contest Club (YCCC)

             LeClerc Consulting
            email: w1tjl at arrl.net
           PC/Network Consulting


On 3/26/2010 11:31 AM, wx5l at charter.net wrote:
> Hello,
>
> This is directed to any quad guru's out there!
>
> I have a 5 band 20 through 10 meter cubical quad. Actually is a GEM quad
> that I've added a small boom to increase the spacing a bit.
>
> Each band is fed out of an antenna switch on the mast through a 1/4 75 ohm
> matching transformer.
>
> I have always had trouble with 10 and 12 meters resonanting properly. I
> recently re-strung both 10 and 12 driven and reflectors with the exact
> demensions call for 1005/f driven and 1030/f reflector.
>
> As long as I keep the 10 meter reflector disconnected 12 resonants fine
> right where it suppose to but when I connect the 10 meter reflector it
> totally changes the resonanting frequencing buy a large margin and the dip
> is unacceptable.
>
> How can I get 10 and 12 to co-habitate. It seems that the 10 meter
> reflector is coupling with the 12 meter throwing things off.
>
> This may be a difficult situation with 12 meters at 24.900 and 10 meters at
> 28.300 how to keep them from coupling with each other. The 12/10 loops are
> physically close to each other on fiberglass arms.
>
> Any idea's to keep these guys from skewing each other off of the intended
> resonant frequency?
>
> Thanks,
> Randy
> WX5L
>
>
>
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