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Date: Sun, 26 Jul 1998 10:20:04 -0400
From: "B. ROHDE - K3XA" <brohde@ibm.net>
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To: Gregg Corsello <quadman@sgi.net>
Subject: Re: quad
References: <35BB27D3.6C1F@ibm.net> <35BB3602.661EA384@sgi.net>
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Gregg Corsello wrote:
>
> Hi, Bill. Well, first the bad news. The 6-element quad on the web site
> is now history also, thanks to 89 mph winds we had here on June 30
> (maybe the 3rd time will be the charm)! I will probably post the
> pictures(of the destroyed 6-el quad) on the site eventually.
> The good news is that I have (unfortunately) had the opportunity to
> see firsthand how these antennas fail WHEN they fail. The 6-element had
> components from different quad manufacturers. Some of them held up.
> Some of them didn't.
> I still use the AL wire from Lightning Bolt.......for the parasitic
> elements only. The driven elements were copper stranded from
> Cubex........I had them in the garage and decided to use them. I would
> use this combination again. I don't need all the weight (and extra
> expense) from copper wire on the reflector and directors.
> The 4-el quad was LB out of the box. One feedline to his xfmr at
> one common feedpoint. It was a fair performer.
> The 6-el quad was a combination of Cubex (spiders), LB(16 spreaders,
> AL wire, some spiders), and Max-Gain Systems (8 spreaders). Coax was
> fed to a remote switch mounted on the boom. From there I had separate
> feedlines to each driven element. I had pre-made 1/4 wave sections from
> RG-11 for each band, then checked the whole thing with my buddy's
> MFJ-259 analyzer. I checked it with AND without the 1/4 wave sections.
> 2 of the bands were actually better without the 1/4 wave sections, so I
> left them off (sorry, I don't remember which ones). So I ended up
> feeding 3 of the 5 bands with the 1/4 wave sections. This antenna was a
> MUCH better performer than the first one. The design was loosely based
> on a QST article from March 1977 (I think) entitled "Evolution of a Quad
> Array".
> Baluns.......beads......good idea, but I didn't use them. The next
> one that goes up will probably have a line isolator at the switch box.
> Bill, I don't know if you already have a quad up, or if you are
> planning on building one. If the latter, some mechanical considerations
> based on my experiences with component failure:
> -any quad with boom length in excess of 16', I would probably use 3"
> O.D. x AT LEAST .125" wall-thickness boom stock. I have had 2 booms
> with .063" wall-thickness fail. They tore like tin cans. The truss
> didn't seem like it helped at all. All it did was eliminate boom sag.
> Jay, K6MB, is using a .250" wall-thickness boom on his 4-element quad,
> and so far it has held up well.
> -Max-Gain systems spreaders are better than Lightning Bolt. I mentioned
> I had 16 Lightning Bolt and 8 Max-Gain spreaders on my 6-element. Well,
> 15 LB spreaders broke; all 8 Max-Gain came thru intact (I think you
> could beat a tree with those things!). LB spreaders are $20 apiece;
> Max-Gain are $17.95, which works out to about $20 apiece shipped to your
> door.
> -I have had several LB spiders bend/break when these antenna failed.
> None of the Cubex spiders bent or broke. Another good source for
> spiders is Antenna Mart. You could get these (Antenna Mart) through
> Allen at Max-Gain.
>
> I truly believe, with the use of good components, you could build a quad
> that would stay up in 100MPH winds.
>
> I hope this has been helpful.
>
> I will be designing my next quad over the winter.
>
> 73, de Gregg, K3QK
> Thanks for info Gregg. I had a 2 el. 20 quad a number of years ago in
> northern NJ and it was basically a Cubex parts item. I held up very well in
> storms, but obviously was just a little 2 el. I'm now thinking of building a
> new 4 el for 20-10 and your info and experience is much appreciated. I'm
> also in the process of constructing a 2 meter EME antenna and will
> incorporate some design strength ideas into that project. I'll be watching
> for info on your web as the new quad is placed into action. Hopefully the
> new design and weather will cooperate for lots of years! Thanks and GL, 73,
> Bill/K3XA
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