Cubex 2 Element 5 Band Quad

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Installed by XX Towers

I'm a big fan of loop style antennas. 

I've experienced their "Band Opening - Band Closing" performances. Loops seem to pick up far less noise and 
more DX. If your tower is of modest height, so much the better as quads can seem to play optimally at about 
45' above ground.

I've also experienced loop's unique maintenance issues such as wires breaking due to high winds and icing. I 
ran a Big Horn Delta Loop that used a gamma match that had a heating problem.  Outputs greater than 500 
watts made the V.S.W.R became erratic. It was fixed with a new Teflon dielectric. But it required yet another 
climb of the tower that felt like a circus act. But that was in the early '90s. Time to try another flavor.

I purchased a CUBEX 2 element 5 band MK Series quad late Summer of 2003. I liked the general
specifications and the features:

	5 bands 
	no traps
	single feedline options (coax switch or factory matching network)
	direct loop feed with coax - serial 75 ohm matching cables supplied witth connectors installed
	fiberglass spreaders - durable and light weight
	short 1 piece boom
	factory tuned via pre-drilled holes in each spreader
	simple design elegance that yields high performance results
	CUBEX performance legacy for quality parts, craftsmanship, and service.

My quad arrived a few days later and I noticed immediately that the packaging for UPS shipment was first class. 
with no broken or missing parts and clear, step-by-step instructions. It included an AMERITRON remote coax 
switch so I could use a single feed line and switch the RF to the right driven element loop for each band. 

Assembly was simple. The 8 foot boom supports single piece cast aluminum brackets for each end's 4 fiberglass spreaders. 
I chose with the tapered spreader arms option. The holes for each band are clearly marked on each spreader. You simply 
thread each band's wire to create the loop. When tight and yet not distorting the spreaders, the length of each loop
is set and then secured.


Picture 1:
I contracted XX Towers owned by Matt, KC1XX for the installation. They started with a quick inspection of my 
assembly, sealed the coax connections with a waterproof sealant, and attached the second element to the boom. 





Picture 2:
They first took down a couple of VHF yagis and got poised to raise the quad. My tower has a thrust bearing and a fairly tall 
mast that served as a gin pole.





Picture 3:
XX Towers ran a rope from the boom to the tower's mast and then used a second rope from boom to ground to keep 
the quad's spreaders away from the tower and house until it cleared the roof line. My step ladder gave just the right 
height to support the boom on its launch until the spreaders lifted up from the ground. It looked and felt like a high wire 
act - and up it went, slick as could be!





Picture 4:
And then the details. Like  keeping the feeds to the switch untangled, rotor cable secure, etc. A quick test revealed
a problem with the AMERITRON switch so off to HRO - Salem, NH for a fast replacement. (The defective switch
was fully credited by CUBEX including the UPS charges to return the switch back to AMERITRON). 





Picture 5:
The quad is fed with hardline that then feeds to the AMERITRON switch so that each band is selected with its 
own direct feed. The 20 and 17 meter bands take direct 50 ohm feed. The other 3 bands use a quarter wave length 75 ohm 
serial matching line that is provided. 

The 75 ohm matching lines short lengths made mounting the AMERITRON switch on the boom most logical. 
That reduces the total number of splice coax connectors and allows just 1 piece of feedline to have to have the turning 
loop allowing for rotation. A quick XX Towers modification to the switch's mounting bracket and a wider than
supplied U-bolt large enough for the boom accomplished this.





Picture 6:
Within an hour, its up with V.S.W.R. at less than 1.5 to 1 on any frequency of the 20, 17, 15, 12, and 10 meter 
bands. 

On the air observed forward gain averages 5 to 10 dB and front-to-back averages 25 to 30 dB. Side rejection is very strong 
and a useful QRM filter. The quad takes key down 1500 watts with no V.S.W.R. variances. Maximum power is now at 100 watts
or less.

Success so far but how will it handle my New England winters? Stay tuned! I'll update this page with any performance 
changes and news. So far, so good.

My primary radios are Elecraft K3/P3 and Flex 5000A with a new Alpha 9500 amplifier.




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