[TowerTalk] Cubex Mantis II

[Jon Pearl - W4ABC]

Hi Dan,

I don't have any experience with the Cubex 40m cubical quads but I still 
have (stored away) a 4 element 10m-20m of theirs that I used for many 
years.  I'm a long time quad fan, starting with a 2 element Gotham with 
bamboo arms, then a 2 element Skylane with fiberglass arms, then finally 
the 4 el. Cubex.

The weakest point in the Cubex design is the wire elements where they 
are formed into corners.  They are comprised of tinned #14 cu and pass 
through drilled holes in the fiberglass arms.  Over time, due to wind 
oscillations the fiberglass will slowly abrade the wire causing 
failure.  It does take some time, though.  My fix for this problem was 
to purchase a black air shock, airline kit.  I have the fiberglass arms 
stack on brackets on my wooden fence and the short lengths of air line 
passing through the arms has shown little deterioration from the years 
in the sun.

I cut the air line into lengths long enough to pass through (and then 
some) each of the fiberglass arms (longer at the fat ends and shorter at 
the small ends) with the wire elements passing through them.  If I 
remember correctly, as the fiberglass arms are shipped, the drilled 
holes are just large enough to pass the supplied #14 but not the air 
line so I re-drilled all of the element holes with an 1/8th in. drill 
bit.  From that point on, I never realized another broken element again.

There are a lot of written words out there by a lot of different authors 
on quads vs. Yagis.  Anecdotally, I know that as a kid getting ready to 
head out the door for high school each morning, I'd always get up early 
to check 10 and 15 and was amazed to often hear that I was one of the 
first east coast stations to be heard across the pond.  Cycles 20 and 21 
were pretty good to me but so was the quad.

I'll close by mentioning that quads are three dimensional antennas.  
I've always been lucky to have all of them mounted on crank-up and 
tilt-over towers.  When something broke, I could aim the boom end where 
the repairs needed to be made towards the ground and then fold the tower 
over.  On a stick tower like the AN Wireless, if a wire element breaks 
on one of your highest corners (40m), you're not only going to be 
dropping the antenna down beside the tower, but it's going to have to 
remain in a boom-horizontal fashion while you attempt to reach the upper 
corner of your 40m box.

Then again... you may well own a crane!



73, Dan,



Jon Pearl - W4ABC

www.w4abc.com

On 3/10/2017 9:52 AM, Daniel Hileman wrote:
> Hi Everyone,
>
>
> I am thinking about putting a Cubex Mantis II Quad (2 elements on 40m, 4 elements 20-10m) on my AN Wireless tower at about 72'.  I am looking to see if anyone has experience with this quad, or other 40m quads, and can tell me how they like it. Looking for real life performance on 40m Vs a 2 or 3 element yagi? I know there is quite the debate on this, but not looking for "opinions" with no operational experience between the two. This would be  quite an undertaking to install and looking for whether those with 40m quads would do it again, and if they thought the performance was better/worse/same as a 2 -3 element yagi.
>
>
> Thanks and 73,
>
> Dan N9WX
> _______________________________________________
>


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