[TowerTalk] Cubex Mantis II

W4AAW@aol.com W4AAW at aol.com
Sat Mar 11 13:24:49 EST 2017


Thanks, Máximo. 

I lived and worked in Europe for 14 years, based in Moscow, Vienna & Budapest.  

While in Budapest, I was a team member at HG5C.  We had problems with the 40M 3-El yagi all the time. 

Laci-HA5MO and Victor-HA5LV came up with a number of long, heavy duty fiberglass poles, suitable for use in construction of a 40M cubical quad.

They studied, designed a built one.  It far surpassed the three element 40M yagi. (The yagi had its own problems.). The quad is still up and works fb.  Every time I work the boys from here (VA) they are potent!

This Spring I plan to replace my 2 element 40M yagi with a similar, and will copy the HG5C 40M quad dimensions.  

73,
Mike
W4AAW



Sent from my Verizon 4G LTE Smartphone

----- Reply message -----
From: "Máximo EA1DDO_HK1H" <ea1ddo at hotmail.com>
To: "Jim Thomson" <jim.thom at telus.net>, "towertalk at contesting.com" <towertalk at contesting.com>, "n9wx at hotmail.com" <n9wx at hotmail.com>
Subject: [TowerTalk] Cubex Mantis II
Date: Sat, Mar 11, 2017 12:28 PM

Hi,


If it is a self-supported tower, best option is to install a "lift". A top part of a guyed tower, the one where the rotator is, and install four wheels. And a couple of U shape rails along the tower.

This roller stuff has a steel wire down to the bottom with a small winch.

This system allows you to lift and lower the antenna with ease. For maintenance or when bad weather.


In this picture you can see a 2 elements quad for 7 MHz, installed in a self supported tower with lift system.



http://www.ea1ddo.es/galeria/albums/EA5CTE/normal_EA5CTE_28429.JPG

[http://www.ea1ddo.es/galeria/albums/EA5CTE/normal_EA5CTE_28429.JPG]


73, Maximo


________________________________
De: TowerTalk <towertalk-bounces at contesting.com> en nombre de Jim Thomson <jim.thom at telus.net>
Enviado: sábado, 11 de marzo de 2017 17:06
Para: towertalk at contesting.com
Asunto: [TowerTalk] Cubex Mantis II

Date: Fri, 10 Mar 2017 14:52:30 +0000
From: Daniel Hileman <n9wx at hotmail.com>
To: TOWER TALK <towertalk at contesting.com>
Subject: [TowerTalk] Cubex Mantis II

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

##  at one time I seriously considered the cubex mantis 2 ele quad, with its 2 els on 40m.  The plan was to install it on my 72 ft trylon freestanding tower.  After looking at the problem from several angles,  I disregarded the quad.
Its a 3 dimensional night mare to install...and maintain.   With its boom just mere inchs above the top of the tower, the spreaders, if in an X.... would be  16 ft above the top of the tower.....and  also 16 ft below the top of the tower,so
88 ft to the top.....and  56 ft at the bottom.   To install the wire loops, the boom 1st has to be installed at aprx 27-28 ft above the ground..on the side of the tower.    The boom is rotated like a big pinwheel, while you install the various wire loops.   Once done, and coax + balun installed, quad is raised to top of tower.  My issue with the 40m quad is.... you have 4 x  26 ft fiberglass poles = 104 ft in total..... none of which radiates, its  just there to support the loops. Thats more than m2 uses on its 80m yagi els.   Thats a helluva lot of windload imo.... vs a shorty 40, with 44 ft els.   My f12  44 ft eles only weigh 12.5 lbs....and have very little windload...and none if pointed into the wind.

## With any vert polarized yagi, or mast out the top of a tower, or quad els, whether mounted in an X  or a  diamond,  you always end up with els that are always broadside to the wind, regardless of direction its pointed.  Several friends had  quads back in the day.....and all were a pita to maintain. One year we had an ice storm, the quads ended up with broken wires on the REF.    All had to come down.  The builders even tried teflon coated stranded wire, thinking ice and snow would not stick.  Nice try, doesnt work, it made it worse.  Back to regular wire.  They even tried raw AC, with a variac, on the DE  to melt the ice, which works, sorta, but not on the REF.   You cant stack anything above or below a quad.   VE7DXQ  added  17 +  12m to his  20-15-10m cubex quad.   17+15 m interacted badly....as did 12 + 10m.  Was replaced with a f12  5BA  20-17-15-12-10m yagi..and a F12  40m rotary dipole above it.

##  Installing a quad on a guyed tower is a gong show, but has been done. Boom next to tower at base..then raised.  Once you get to 1st set of guy wires, they are removed at the tower, boom raised a bit, then 3 x guys re-installed.  3 x temp guys used for safety.   Moot point with a free standing tower.

##  IF u dont have ice, heavy wet snow, or high winds,  or any combo of ice + wind,   you will probably be ok.     The 2 el  40m quads I have heard were flame throwers on 40m.  But none lasted more than 2-3 years till  problems started.  With a self support tower, even with a broken wire,  you could still lower it down the side of the tower, rotate the boom, till you got to the problem area, then repair it.    You might want to get names of actual mantis owners, and get their opinions 1st.     A lot of water under the bridge, and cubex may well have beefed them up considerably.

Jim  VE7RF
_______________________________________________



_______________________________________________
TowerTalk mailing list
TowerTalk at contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
TowerTalk Info Page - Contesting<http://lists.contesting.com/mailman/listinfo/towertalk>
lists.contesting.com
TowerTalk is for discussion of tower and HF antenna construction topics. TT members have lots of helpful information and are happy to share it.


_______________________________________________



_______________________________________________
TowerTalk mailing list
TowerTalk at contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk


More information about the TowerTalk mailing list