Building a cubex quad

[unit_399]

About 10 years ago, I built a 2-element quad using whatever parts I could find that would work. I designed it using the info that I found here:
https://www.lral.lv/4_element_quad.htm

I made the boom out of 2" schedule 40 yellow drainage pipe. The hubs were made from cable reels that the mujer at the local hardware store gave me. The spreaders were 3/8" dia extruded aluminum curtain rods with 3 foot 1/8" dia fiberglas rod stock on the ends. I used #10 enameled copper motor winding wire for the elements. I wound a matching balun to get the correct 50 ohm impedance and also wound a choke to eliminate common-mode currents.


Hub and spreader arm assy. I clipped the screws and cleaned up the rough edges



Finished antenna mounted atop a 36' guadua pole. The black square at the bottom of the antenna is the common mode choke. This antenna worked flawlessly for 5 years. I lost it in a horrendous windstorm because I never guyed the guadua mast which snapped at the base. I won't make that mistake again.


The antenna on the day we put it up. Just barely beat the rain. The things that look like guy wires are actually the ropes we used to pull it up.

This was a great antenna and I used it to communicate with many forum members in the US. Once I got all of the parts together it only took a week to assemble.

- 399

 

[The DB]

du•ra•bil•i•ty

n. The quality of being durable; the power of lasting or continuing in the same state by resistance to causes of decay or dissolution.
n. The state or quality of being durable; the power of uninterrupted or long continuance in any condition; the power of resisting agents or influences which tend to cause changes, decay, or dissolution; lastingness.

n. Permanence by virtue of the power to resist stress or force.

I guess you somehow think that I don't already know this... Or is it that you want to distract from the truth of the matter again?

less wind loading not only implies durability but the two are inversely proportional to one another. wind loading increases stress in materials, they lose their ability to resist the wind loading forces, especially with the addition of freezing and icing conditions, they become fatigued and they fail. wind loading increases force, stress and the "durability" of the materials is (compromised) decreased.

I would look at it differently, but it doesn't matter. Even with your interpretation, my statement above still stands. You are leaving certain very important parts of it out, so I would say incomplete is a good word to describe your stance. Its like you have never worked with quads before, or if you have you haven't worked with equivalent yagi antennas. The difference in materials is like night and day. Its so much that the typical quad tends to fail much more quickly than the typical yagi. An this isn't even considering other shortcomings of the quad design, such as the wire stretching issue that @AudioShockwav mentioned above, and that is just one of them. Also, when it comes to frosting and freezing that you are saying will affect yagi's more, I'm sorry but I've seen just the opposite, as has @BJ radionut in a post above. Also the materials used with quads are inherently irreparable, as @BJ radionut said above where most damaged yagi's I have seen are very repairable.

So with that, I'm sorry but your claim that a quad is more durable than a yagi simply because it has less wind loading doesn't match what I and many others have experienced with these antenna designs.


The DB

 

[freecell]

you posted:

"Less wind loading does not imply more durability." no interpretation is required for that which is plainly stated, the statement is false.

reducing wind load on both the support structure as well as the antenna itself is key to preventing material fatigue (increased durability of materials) and "keeping" both of them up and in the air.

less wind loading not only "implies" more durability, they go hand in hand with one another.

do you have a quad or yagi antenna of any size and have problems with wind damage? when the wind is blowing you can affect a huge decrease in antenna wind loading simply by turning it so that the boom is perpendicular to the direction of the prevailing winds and for those with telescoping masts or towers simply lower them to the ground until the wind passes. the higher and wider the support structure the higher the wind load will be. both quads and yagis can perform exceptionally well at a height of one half of a wavelength above ground and stand a much better chance of riding the storm out undamaged.

as for those snow storms and icing conditions, you may want to give some serious thought to relocation. even under these conditions the tips above will be helpful and it's always warmer close to the ground.

nowhere have i seen any evidence attesting to the fact that my experience has to be the same as yours or anyone elses and as a matter of fact my experience is quite the opposite. i'm not about to apologize to anyone for that being the case. you can choose to do something about it or not, while i can explain it for you i cannot understand it for you. no further responses in this thread by me will be forthcoming.

if anyone wishes to challenge anything i've stated here or wishes to continue this conversation further, i'm assuming you know what to do.

 

[The DB]

"Less wind loading does not imply more durability." no interpretation is required for that which is plainly stated, the statement is false.

This statement is objectively true. Your not even considering the materials the different antennas are made out of and what they can and cannot handle. As I said above, if the two antenna designs were made out of the same materials this would be true, but they are not. If you don't take everything about the antennas into account, then you are doing nothing but putting out an opinion based on incomplete information as fact. Actually, at this point I think your just trolling.

reducing wind load on both the support structure as well as the antenna itself is key to preventing material fatigue (increased durability of materials) and "keeping" both of them up and in the air.

Here you are using incomplete information again. This would be true if both antennas were made out of the same material... There must be an echo in here...

less wind loading not only "implies" more durability, they go hand in hand with one another.

The problem with this is, again the materials that most manufacturers use to make quads simply cannot handle the stresses that quads are put under with their lower amount of wind loading, while the typical yagi design not only handles the wind loading much better, but the built up fatigue as well. That is three times in one post that all you need to do to get to the truth is add in the effects of materials, something you seem incapable of doing.

do you have a quad or yagi antenna of any size and have problems with wind damage? when the wind is blowing you can affect a huge decrease in antenna wind loading simply by turning it so that the boom is perpendicular to the direction of the prevailing winds and for those with telescoping masts or towers simply lower them to the ground until the wind passes. the higher and wider the support structure the higher the wind load will be. both quads and yagis can perform exceptionally well at a height of one half of a wavelength above ground and stand a much better chance of riding the storm out undamaged.

Yes I have, I've seen several, and its clearly not just me. But then, I do live in tornado alley... Its a great testing area for antenna survive-ability.

Yes yes yes, turning the quad and yagi so the boom is perpendicular lessens the effect of said wind loading. I am also aware of the effects of changing the height of the beam. In both cases, given the same heights and proper angles of the antenna, the quads consistently fail before the yagi antennas.

as for those snow storms and icing conditions, you may want to give some serious thought to relocation. even under these conditions the tips above will be helpful and it's always warmer close to the ground.

Again, something I already know. Its like you think your talking to a rank amateur here...

nowhere have i seen any evidence attesting to the fact that my experience has to be the same as yours or anyone elses and as a matter of fact my experience is quite the opposite. i'm not about to apologize to anyone for that being the case. you can choose to do something about it or not, while i can explain it for you i cannot understand it for you. no further responses in this thread by me will be forthcoming.

You are allowed your opinion, and its fine that your experiences are different. The difference here is I'm not just basing this on my own experience. I am also factoring in the wide range of claims collected from not just myself, but the various radio clubs I have been a member of, and the collective knowledge of many other people's experiences on many different forums, news groups, many articles and books on the subject, and even more.

You are presenting an opinion based on one thing, that is wind loading. The problem is, there are other thing in play, namely the durability of the components commonly used to make the antennas are very different (that echo is still here...), and you refuse to even consider factoring this in. There are also known problems with the quad design as presented above that you also refuse to even consider. You cannot categorically say that one antenna is more durable than the other without factoring in all of these, yet you choose to ignore these completely. Well, if this is the hill you choose to die on.

In the end all you are doing is presenting an opinion based on incomplete information as an absolute fact not to be questioned. I tend to questions these so called "facts". And strangely, all you had to do was address the concerns that were brought up, but you simply ignored them.


The DB

 

[Cody Dixson]

... quietly sits sideline after asking question...

I'm down here in northern Arkansas so wind snow ect. Is an issue in my area.

I dare to ask now ,what about a moxon???

 

[freecell]

moxon for 11 meters:
https://www.worldwidedx.com/threads/moxon-for-11-meters.168469/

 

[Cody Dixson]

@freecell thank you for the info!! I've got some decisions to make lol

 

[freecell]

you're welcome Cody.