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Author Topic: Why so many more Yagis than quads?  (Read 5948 times)
AE5X
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« on: June 21, 2012, 04:17:54 PM »

Evening folks,

After 34 years in the hobby I'm finally having a tower installed. Up to now it's been dipoles; 288 countries' worth (no, it didn't take 34 years to ge tthat count). But it's time to move on...

The tower will be a 50' Rohn 25 installed behind my garage and I have to decide what antenna goes atop it since the installer will be putting up the antenna as well as the tower.

I gotta say, the quad (2 el GemQuad) looks good compared to 3 and 4 element Yagis - lighter weight, smaller turn radius, equivalent gain and the ability to be WARC-capable simply by adding the wire. I live in STX so there are no issues with snow/ice.

A 20 ft turn radius is available - a sweetgum tree prevents more - that will accomodate the quad (easily), or a 3-4 element triband Yagi. It's a tough decision.

If anyone else has been down this road, as Ross Perot says - I'm all ears.

TNX/73,

John AE5X
http://www.ae5x.com/blog

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WX7G
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« Reply #1 on: June 21, 2012, 04:32:09 PM »

  • Yagi's last almost forever whereas the wire on quads does not.

    Installing a quad is an experience being that it's three dimensional.

    Yagi's can have better ice and wind loading capability.
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WB6BYU
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« Reply #2 on: June 21, 2012, 05:19:56 PM »

Quote from: AE5X

I gotta say, the quad (2 el GemQuad) looks good compared to 3 and 4 element Yagis - lighter weight, smaller turn radius, equivalent gain and the ability to be WARC-capable simply by adding the wire...




The gain of a 2-element quad is less than a well-designed monoband 3-element yagi.
After making various compromises to get three bands on a yagi, it's a tossup, and
will depend on specific models and varies from band to band.

One problem with the quad is that the elements extend further below the boom, and
that needs to be considered when choosing your mast height if the tower is guyed
at the top (as should be the case with 25G.)  This also depends on the angle of your
guy wires.

Installing a 3-dimensional antenna is non-trivial, as WX7G commented.  Not that it
can't be done, but it may take more work.  (And you need space to assemble it on
the ground.)   You might check with the installer to see what his experience is in
this regard.

As far as reliability goes - ask around the the locals to see what their experience is
with quads holding up in the local wind conditions.


In the end it's your decision:  some choose one, some the other.  Certainly being able
to have gain and directivity on the WARC bands is an advantage.
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K3VAT
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« Reply #3 on: June 21, 2012, 05:53:15 PM »

Evening folks, ...

The tower will be a 50' Rohn 25 installed behind my garage and I have to decide what antenna goes atop it since the installer will be putting up the antenna as well as the tower.

A 20 ft turn radius is available - a sweetgum tree prevents more - that will accomodate the quad (easily), or a 3-4 element triband Yagi. It's a tough decision.  ... 73,  John AE5X

John,
Others have summarized the benefits of the yagi over the quad.  Even though you have limited air space you can put up a 5 band yagi (well, 3 elements on 10, 15, and 20 PLUS WARC Dipole).  One solution is the Mosley Mini33-AW (see: http://www.mosley-electronics.com/pages/amateur/mini33aw.htm).  Mosley has been around a long time and these systems are time & performance proven (albeit at 500 watts max).  You'll see that the turning radius is less than 11 feet.  Don't let others dissuade you by saying that trap antennas are poor performers because traps are so lossy that they eat up all your power.  Modern traps used in Mosley, HyGain, Crushcraft for example exhibit very low loss (see the article on http://www.w8ji.com about trap performance).  Another shorty yagi is made by N6BT (founder of Force12 Antennas) - see Tom's website: N6BT.com.

50 feet of tower, (may be a couple more feet on your mast) will elevate these yagis up to a decent height whereby you will be able to work on world on these 5 bands.

GL, 73, Rich, K3VAT
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WB6BYU
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« Reply #4 on: June 21, 2012, 09:58:02 PM »

One thing I remembered about adding the WARC bands to the quad - it isn't as
easy as it might sound.

The problem is that, for example, while there isn't a lot of interaction between
the 20m and 15m elements, adding one in between for 17m causes complications.
The short of it is that the 15m reflector looks like a director on 17m, and the
17m reflector looks like a director on 20m.  So how does such an antenna
perform on bands where there are both a director and a reflector in the
same plane?

Here is one of the late W4RNL's article on the subject:

http://www.cebik.com/content/a10/quad/qab.html

He has a lot of other information on the website that may be useful.
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STAYVERTICAL
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« Reply #5 on: June 21, 2012, 11:04:04 PM »

Hi John,

If you can put up the yagi, I would go with that.
They perform well and have physical robustness which means less repairs, and tower climbing.
Quads perform really well, no doubt about that, but yagi's are just as good in practical terms.
I have tried a few quads, and they are great, but it becomes very frustrating managing the thing close to the ground.

If you want to dip your toe into the wire beam arena, perhaps a 5 band hexbeam would be a good interim experiment.
They work well, equivalent to a 2 element yagi, have a symetrical low wind load factor, are light, and inexpensive.

But if it were my choice, a 3 element or better yagi would be on my shopping list.

73 - Rob
« Last Edit: June 21, 2012, 11:05:36 PM by STAYVERTICAL » Logged
AE5X
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« Reply #6 on: June 22, 2012, 05:31:00 AM »

Thanks for all the comments guys - I appreciate it. A landline QSO with WG5G last night has me just about convinced to buy a Hazer for the tower. This would allow me to install an antenna at my leisure and to easily do work on it w/o having to climb the tower. It would also allow me to defer the antenna purchase since there would be no deadline for having it ready when the tower guy is here. (For those who don't know of WG5G, he has 340 confirmed with 5 watts/quad).

I just wish reviews of the 3 Hazer systems were more favorable...

John AE5X
http://www.ae5x.com/blog

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WB2WIK
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« Reply #7 on: June 22, 2012, 09:28:41 AM »

A Hazer with a quad might present more problems.

Rohn 25G obviously must be guyed, and the upper set of guys should be at the top of the tower, or very close to the top of the tower.  Since a quad extends as far below its mounting point as it does above, the quad will likely swing into the upper guy wires unless the mast above the Hazer mounted rotator is quite long, in which case it can exceed the design limits for the Hazer, even the galvanized steel one.

Some guys like the Hazer, but I always found them more trouble than not using them. Wink

To lower a Hazer on a guyed tower, step 1 is to disconnect the guy wire(s) that will be in the way of its coming down.  That's work, takes time, and should really only be done on a calm day or you risk the tower.

Step 2 is to lower the Hazer until the next set of guys, and then disconnect the guy wire(s) that will be in the way of its coming down.  Of course, this work is done at ground level (guy connection points with anchors), but it's still work and takes time, and a smart approach would be to re-connect the upper guy as soon as the Hazer is past it, so you're never left with two unguyed points at the same time.  A gust of wind could ruin your day like that.

For me, by the time I go through all the trouble of lowering a Hazer on a 50' guyed tower, I could have climbed the tower twice. Smiley

In any case, if you go with the Hazer system, I'd use a 2d beam design and keep the mast above the rotator fairly short, as they recommend.
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NN4ZZ
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« Reply #8 on: June 22, 2012, 11:48:33 AM »

If you really like Quads and want to see a solution to the 3 dimensional maintenance issue, you may be interested in this:

http://www.nn4zz.com/quadlock.htm

From NN4ZZ, the TiltPlate company.

Regards, Al / NN4ZZ
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WA8UEG
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Posts: 339




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« Reply #9 on: June 22, 2012, 12:11:22 PM »

Over the years I have used both, the quad as yielded much much better results then any 3 element beam I have had especially at mounting heights of 40 or 50 feet. Mine is very old, purchased in the 70's and has been used at several locations. Currently it has been up for about 8 years in the Pocono Mountains in Pennsylvania and has seen lots of wind and lots of ice and has handled it with no problem. One thing I would highly recommend is replacing whatever wire is supplied with copperweld. The copperweld will not stretch and will make a big difference keeping the spreaders from failing because of wind or ice acting as support wires for the spreaders. My 20/15/10 quad works well, in fact very well on 17 & 12 using the auto tuner on my FT1000MP. I have a MFJ998 legal limit auto tuner behind the amp if more power is required on those bands but seldom is except for "rare ones" where you would encounter pileups.
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WA8UEG
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« Reply #10 on: June 22, 2012, 12:15:45 PM »

If you really like Quads and want to see a solution to the 3 dimensional maintenance issue, you may be interested in this:

http://www.nn4zz.com/quadlock.htm

From NN4ZZ, the TiltPlate company.

Regards, Al / NN4ZZ

This is very handy for quads, mine has the Hy Gain boom to mast clamp that allows for tilting and is a huge help.
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KE4VVF
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« Reply #11 on: June 22, 2012, 01:58:59 PM »

Quads like to fall down.... go boom.
Mongo Like Yagi.



Seriously, I chose Yagi because they have higher wind /  ice survivability and generally require zero maintenance for at least a decade.  It's about as close to plug and play as you can get. 
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WA8UEG
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« Reply #12 on: June 22, 2012, 02:29:47 PM »

No pain....No gain Wink
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W8GP
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« Reply #13 on: June 22, 2012, 03:45:11 PM »

What about a log periodic? Gain is generally lower than a yagi, but still substantial compared to a dipole and the efficiency is much higher.Front to back is  very good as well. I've been using one for about 6 years and am more than pleased with it.
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WA8UEG
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« Reply #14 on: June 22, 2012, 03:52:12 PM »

What about a log periodic? Gain is generally lower than a yagi, but still substantial compared to a dipole and the efficiency is much higher.Front to back is  very good as well. I've been using one for about 6 years and am more than pleased with it.

Off topic but NICE shack.
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