[TowerTalk] 6 mtr quad

[Joe Giacobello, K2XX]

> Jim Thomson <mailto:jim.thom at telus.net>
> Thursday, September 01, 2016 10:09 AM
> Date: Wed, 31 Aug 2016 13:44:25 -0400
> From: "Joe Giacobello, K2XX" <k2xx at swva.net>
> To: sawyered at earthlink.net
> Cc: towertalk at contesting.com
> Subject: Re: [TowerTalk] 6 mtr quad
>
>
> I am currently using a two element duobander on 30 and 40M on a 20 foot
> boom. It's almost equivalent to a three element monoband Yagi but on a
> far shorter boom. Cubex's 26 foot spreaders have held up well at this
> windy QTH, although the combination of ice and wind can be destructive.
>
> 73, Joe
> K2XX
>
>
> ## 104 ft is nuts. A full sized 40m yagi element is typ 62-74 ft. 
> Heck, a buddys
> m2 80m yagi uses 101 ft eles.......on 80m, shortened of course.
> The F12 340N uses 52-59 ft long eles, aprx 85% full size, and is only 
> 10.3 sq ft,
> 135 lbs.
Well, hardly nuts.  First, It does work and it's been up about ten years 
with relatively few problems.  Remember those spreaders taper down from 
about a 1.5 inch diameter to around a quarter inch at the tips.   A 
three element Yagi has three +/- 65 foot elements and around a 40 foot 
boom.  That's not a trivial cross sectional area and a lot more weight.  
I have turned the quad with either a Ham IV or a T2X. Heavy winds can 
make turning difficult, but I suspect there's little difference with a 
40M Yagi.  Flexing spreaders during high winds have not caused me any 
problems.

Your poor experiences with quads may have been in the early days when 
the quality and strength of the fiberglass was far poorer than that 
available today.  I remember when I was first planning the 40M quad, I 
spoke with W4QN, who was then the owner of Cubex.  His spiders (hubs) 
had arms only about (IIRC) 8" long, which I considered much too little 
support for the butt end of the spreaders.  He assured me that there 
would be no problem, and he was right.  I had considered trussing the 
quad a la Gem quad, but it hasn't been necessary.  Of course, you guys 
up in the North Country have a different set of conditions to deal with, 
which is the reason those Gem quads were so sturdily designed.  (I never 
realized that the "porcupine" spreader mount was a problem with snow/ice 
accumulation.)  OTOH, we do often get ice storms, wet snow and serious 
winds here in the Blue Ridge.

I agree re the free standing tower, and I use LM-470s here.  When I 
originally built the 40M quad, I had used #12 Teflon coated wire (not 
cheap) too and with the same expectation regarding minimal ice/snow 
buildup.  At that time my four element multibander was also up but with 
bare wire.  There was little or no difference between the two antennas 
re icing.

73, Joe
K2XX

> ## One really needs a freestanding tower...or a freestanding crankup 
> when using quads.
> Back in the 70s, I helped a local buddy install a 4 el cubex on top of 
> his 60 ft tall rohn 25 tower.
> The only way it could be done was to remove the guys at the tower..as 
> the boom was raised
> past each guy station...pita, never again. Then the quad was mounted 7 
> ft up the mast....and the
> mast bent in a high wind one day. Another gong show.
>
> ## Then helped another ham with his 5 el cubex..on a 70 ft 
> freestanding tower. One day a 75 mph
> wind comes along..and trashes his rotor..and also a spreader....at the 
> end of the boom on the REF..
> another pita. Once all fixed, next up was a once in 20 year ice storm, 
> with .375 inch ice build up.
> Wires broke on the 20m REF.....down it comes again. This time he used 
> teflon coated wire, thinking
> ice would not stick to teflon. Wrong, sticks like glue, and more 
> problems.
>
> ## meanwhile, another local, with his gem quad has snow build up 
> issues. The snow was packed in
> super tight, where the 8 x spreaders all converge into one point. 
> Looked like a 1 cubic yard block of snow.
> Those spreaders they use, may well have won some BS engineering award 
> in VE4 lands years ago, but they
> attract snow and ice really bad. All these guys kept a 15-20 ft long 
> pole at the top of the tower...so they
> could climb the tower, and use the pole to smack snow + ice off 
> everything.
>
> ## after being in on several of these up-down-up-down-up-down quad / 
> delta loop install and repair
> efforts, I vowed to never own one. Seeing broken wires and broken 
> spreaders tangled up with the guy
> wires of a guyed tower will make you cringe. Then u get the other 
> issues, like high winds..and flexing spreaders,
> at which point the wire loops all go slack.
>
> ## The 2 el, triband quad was a good ant in its day. One fella here in 
> town worked 300 countries with his gotham
> quad, and had minimal issues with it.
>
> Jim VE7RF
>
>
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