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Author Topic: 2 Element 40 meter Beam Recommendations  (Read 4503 times)
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w0vt
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« on: July 30, 2014, 02:03:38 AM »


I am wanting to install a shortened 2 element 40 meter beam at my QTH. Years ago I had a HyGain 402BA, but when I moved I took it down. (I still have it.) I initially wanted to reinstall it after refurbishing it. However, I understand the boom length is short plus the linear loading placement causes high voltage points on the insulators causing electrical breakdowns. That said, I am now thinking of buying a new 2 element shortened beam. I've done minimal research and see there at least 6 manufactures of these type antennas. (A couple have taken my breath away financially.) My feelings right now are I don't want to spend more then around $1000 for the antenna unless there is a very good reason to spend more. I run high power AM and I know this might be a BIG factor in what I choose.  (I am  not sure most of these shortened antennas can handle legal limit AM power.)

 Can you guys give me a little help deciding which antenna I should consider purchasing and reasons why? (2 element shortened 40 meter beam) (I live in the Houston, Texas area, so ice loading is not a factor. The antenna would be around 48 foot up in the air.)


 Thanks,

 Lee, w0vt

 Texas
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w4bfs
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« Reply #1 on: July 30, 2014, 08:49:35 PM »

hi Lee .... I also have one of the Hygain ll 40m beams .... the element lengths are close to 40 ft .... I was thinking of using 80 ft of wire on each element and making a 2 el quad out of it .... spacing would be ok ... would need to go up with a pipe at the element centers and guy the elements with insulated uv resistant rope .... a weight at wire bottom ... don't rotate too fast
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Steve - K4HX
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« Reply #2 on: July 31, 2014, 06:28:20 AM »

Take a look at the Moxon designs or mod kits.
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n1bnc
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« Reply #3 on: July 31, 2014, 08:26:11 AM »

WA3FET design is a good way to go. Designed by contesters, so power should never be a problem.
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Chuck...K1KW
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« Reply #4 on: July 31, 2014, 11:36:47 AM »

I have the old Cushcraft 2 element shorty, in fact two of them stacked, for over 20 years.  I know MFJ now owns Cushcraft but it is a decent performing antenna.  Not sure what the price is these days.  The elements are 44 ft long with inductive and capacitive loading on the ends so it is pretty efficient.

Years ago I modeled it including the inductor with its losses and it was down about 0.5 dB from a full sized antenna. F/B is 12 to 15 dB but when you stack a pair of them, it goes up to 20 to 25 dB for the stack.

I have run a full plate modulated KW into one of them with no issues.

If MFJ didn't screw up the design or cheapen it, I'd buy it again.  One caution though.  The inductors are connected to the elements with galvanized sheet metal screws that eventually rust and lose connection.  This happened to both of mine after about ten years.  I fixed it by using 10/32 stainless bolts through the elements and that is quite solid.  That was the only problem with the antenna.  The antennas survived several hurricanes and a major ice storm.  There is a picture of it on my QRZ.com page.

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73, Chuck...K1KW
Steve - K4HX
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« Reply #5 on: July 31, 2014, 07:46:03 PM »

Chuck brings up some good numbers on gain and FB ratio. What is more important, forward gain or FB? Only you can answer this. But, no matter what, you will only get 3-4 dB gain with two elements. The typical yagi will yield the FB numbers Chuck posted. A Moxon will produce FB ratios of 20-25 dB. So, if you find FB more important, the Moxon seems the better choice.

At my location, FB was more important than gain. I could hear stuff other could not. I am using a HB delta loop array.

In any event, I don't think you'll ever regret putting up a good directional antenna on 40 meters. Good luck.
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K1JJ
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« Reply #6 on: July 31, 2014, 09:58:57 PM »

Yes, stacked 2 element Yagis overcome the poor f-b of a single 2el.  And I also like the Moxon's f-b performance for such a small and simple 2 el beam.

Another inexpensive alternative is to put up a pair of fixed, wire, phased, coax-fed 40M dipoles.  Make them switchable NE / SW  and a second pair  NW/SE to cover all directions.  At 50' or higher, it is a killer antenna.

As for aluminum rotatable  40M Yagis, expect to spend from $600 to $2K depending on the manufacturer and whether it is a shortie or full size.   A great alternative is to visit the metal recycling scrap yard and buy the tubing for $1-$2 / pound as I have.   Using Yagi Stress software for mechanical design and  Yagi Optimizer for electrical design and element tapering, I built the  triple Yagi stack from scrap. Shown below, it cost me about $1K including stainless steel clamps, hardware, etc.  (full-size elements, no coils) This was seven years ago so prices may be higher, but it is still up and working FB. Stacked at 60', 125' and 190', the takeoff angle is at about 13 degrees - the best performing antenna I have into Europe and Russia.

Good luck wid the project, whatever you do, OM!

Tom, K1JJ


* 4X1 Rig 157.jpg (322.69 KB, 960x1280 - viewed 345 times.)

* 4X1 Rig 159.jpg (330.65 KB, 1280x960 - viewed 373 times.)

* YazPics 042.jpg (328.66 KB, 960x1280 - viewed 338 times.)
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Use an "AM Courtesy Filter" to limit transmit audio bandwidth  +-4.5 KHz, +-6.0 KHz or +-8.0 KHz when needed.  Easily done in DSP.

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WBear2GCR
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« Reply #7 on: August 02, 2014, 02:31:17 PM »

I'm not personally familiar with these beams.

But why not put a longer boom on the Hygain you have and fit it with improved insulators?
Seems to be not a terribly expensive or difficult job. Of course there may be things I don't know about that particular beam that make this nice idea unworkable...

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