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Author Topic: Real time Comparison with HEX Beam and Mono Band Mosley Yagi will be interesting  (Read 73050 times)
G3TXQ
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« Reply #15 on: February 14, 2011, 06:28:36 AM »

Tom,

Can you confirm what you said in your original post: that you called all Hexbeam manufacturers and were told by them all that a Hexbeam at 30ft to 35ft was a match for a 3-element monobander 10ft to 20ft higher?

Steve G3TXQ
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WA8UEG
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« Reply #16 on: February 14, 2011, 06:33:23 AM »

Hex beams are shortened 2L yagis.

A 3L yagi on a substantially longer boom should blow it away.

Test finished. Cheesy

Oh Yea, count on it. Like compairing Randy Johnson's fastball to mine. 

I heard your fastball is pretty good.



40+ years ago about 83 MPH, today reversing the numbers would be close but would require a week of therapy to use the arm again. Grin
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K0OD
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« Reply #17 on: February 14, 2011, 07:27:50 AM »

"40+ years ago about 83 MPH"

My favorite piece of test equipment is my $900 Stalker Sport radar gun from my son's HS and college pitching career.  Frankly I got tired of hearing people (high school Dad's mostly) bragging about how fast their kids threw and I decided to see for myself.

My gun is the same one most pro teams use but it is far from being consistent.  I've watched multiple guns on tripods at minor league scouting sessions. Side by side guns can register many MPH different.

Never once found a pitcher who threw faster than claimed. As a general rule kids throw about 6 mph slower than the parents think. That's at HS level. By college, both kids and Dad's have figured out the disappointing truth. (notice how everyone thinks those carnival guns are way low? They're NOT)

But pitchers are like antennas. They have many parameters. We had a kid on our HS team with 1.60 era who topped out at 68 mph.

How fast can Dad's throw? I brought a very primitive device to my kids practice when he was about 12 (and Dads were younger). One 45-ish burly dad topped out at 56 mph.
 
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WB2WIK
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« Reply #18 on: February 14, 2011, 09:14:10 AM »

I threw a 90 mph fastball once.

It wasn't that hard.

Drove 90 mph in the car, opened the window, tossed the ball out.
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K0OD
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« Reply #19 on: February 14, 2011, 09:24:12 AM »

Coming back from an away game and bored with the long highway trip, I aimed my gun thru the (passenger side)  window at oncoming trucks. Gun measured up to 145 mph!

Pretty scary!
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N9MXY
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« Reply #20 on: February 14, 2011, 04:16:24 PM »

Longer ago than I care to think about I could serve a racquetball at 120MPH+ :-D
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STAYVERTICAL
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« Reply #21 on: February 14, 2011, 07:14:10 PM »

Hi Tom,

I think it will be very interesting to see the results of your tests.
In my many years of antenna construction and experimentation, I never fail to be surprised by the ways practical antennas vary from the theoretical performance.
Obviously, in the real world of residential ham antenna environments, many factors apart from the free space performance of the antenna come into play.
One thing I have found to really make an antenna punch above its weight is when the elements are closely coupled.
The bandwidth generally falls, but the gain and directivity rise dramatically.
It is of course difficult to match and is not a setup and forget system, but since I use a remote ATU on the driven element this is no problem.
Another factor is reflector element tuning, which can change the performance enormously, especially on a close coupled setup.
I use a small screwdriver motor to physically wind the ends of my reflector, and the change in front to back is huge at the sweet spot.
The hex beam is a fairly close coupled antenna, and from my personal tests with a friend about 30km away, it has an awesome front to back ratio, in his case anyway.

I also use a vertical with a diagonal reflector close coupled (6 feet away at the base), on 20m and it performs very well.
Not as good as a tower mounted 3 element yagi of course, but way above a naked vertical.
Again, I use a low speed motor on the reflector wire as a tuning unit to adjust for maximum front to back ratio.
If I had just blindly accepted the dogma of "verticals radiated equally poorly in all directions", or whatever other bias is prevalent, I would not be enjoying the benefits of my effective antenna now.
Too many people these days are "armchair generals/engineers/experts" and only serve as an anchor and brake to those who are excited and ready to experiment.

In the end, experimentation is what ham radio should be about - we are probably not going to find any hidden knowledge mystical antennas, but each one of us can add his or her curiosity-led findings to the mix.

Good luck with your tests and experiments - that is the real spirit of ham radio.

73s
« Last Edit: February 14, 2011, 07:17:48 PM by STAYVERTICAL » Logged
N4JTE
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Posts: 1169




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« Reply #22 on: February 14, 2011, 08:03:00 PM »

Tom, I for one will look foward to the results, hoping you will write an article for eham on your findings. I occasionaly write comparison tests and run into the usual crap about correct testing facilities etc. but I have provided a lot of good real world info for other hams attempting wire antennas on 40 and 80. With you getting into actually testing the crazy gain figures published on these antennas on the upper bands your experiences will be well worth the effort and interesting to all of of not blessed with a convenient test range.
The test against a monobander should only go one way, but as you say those hex beam adds might have a lot of splaining to do, hi.
Have fun,
Bob
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K0OD
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« Reply #23 on: February 14, 2011, 08:37:12 PM »


Quote
"But imagine, if for example, the HEX Beam is only one S Unit less, (Which every one says is 6DB,)"

Truth is that one S-unit might just be a dB or two.

"S Meters are clearly not very accurate nor consistent, although some are better than others. In some radios, the S Meter calibration is a function of frequency. Your S Meter may differ from mine, even in the case of the same brand and model of radio. If you want to trust and know your meter, you should spend some time with your receiver and a calibrated signal source, mapping S Meter deflection to known dB changes."
http://www.seed-solutions.com/gregordy/Amateur%20Radio/Experimentation/SMeterBlues.htm
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G3TXQ
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« Reply #24 on: February 15, 2011, 01:19:01 AM »

OK - I'll ask the question one last time. If Tom declines to answer, I'll just have to speculate on the reason:

"Can you confirm what you said in your original post: that you called all Hexbeam manufacturers and were told by them all that a Hexbeam at 30ft to 35ft was a match for a 3-element monobander 10ft to 20ft higher?"

I have been involved with the hexbeam enthusiast community for about 3 years, and developed the Broadband version which is currently sold by K4KIO, DX Engineering and MW0JZE. I have no commercial interest in these companies but I do talk to the folk who run them. We have been keen within the community not to make exaggerated claims for the antenna's performance; you will find that philosophy reflected on my web site and, as far as I know, in the advertising from these companies.

That's why I was disappointed to hear that Tom had talked to these companies and was told the hexbeam at 30ft to 35ft was a match for a 3-element monobander 10ft to 20ft higher.

I also note Bob's throw away comment that: "those hex beam adds might have a lot of splaining to do, hi". Could he please say which ads he is referring to?

73,
Steve G3TXQ

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G3TXQ
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« Reply #25 on: February 15, 2011, 01:31:32 AM »

In my many years of antenna construction and experimentation, I never fail to be surprised by the ways practical antennas vary from the theoretical performance.
My experience with developing the hexbeam has been the exact opposite. I am regularly surprised just how close the measured performance is to the theoretical predictions.

There's a page on my web site comparing measured performance with model predictions:
http://www.karinya.net/g3txq/hexbeam/eznec2/

73,
Steve G3TXQ
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NN2X
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Posts: 232




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« Reply #26 on: February 15, 2011, 08:01:16 AM »

Steve (G3TXQ)

Make no mistake about it, I was verbally told that the HEX beam is equal to the a 3 element Mono bander (3 Element), (By various HEX manufacturers) and does not need to be as high to get effective results..The 10 to 20 FOOT came from the claim of 50 Tower versus (MONO Bander), the a 30 Ft Tower (Hex Beam) comparison (Or at 35 FT). I am 52 years old, I have no reason what so ever to lie..It is not my character…So please lets move on…I am not going into a he said she said dialog, no matter what, you will never believe what I say, anyway..


But lets find some common ground..(And this is the most important)! And lets just say I was delirious on the phone with the HEX Manufactures

Now from this forum…Lets see if you at least agree with the below..


1. Hex Beam has 3 to 4 dbd of gain over a dipole (Correct)?

2. MONO Bander 3 element yagi has no more then 6dbd no matter the design (More then likely 5.5dbd)Correct?

3. Each "S" unit is 6dbd on HF Transceivers (Correct)?

4. Hex Beam works equally well even though at lower heights (In our case only 5ft LOWER)

5. If the above is correct, then when comparing the antennas, MONO Bander Yagi from Mosley at 24FT, and a HEX Beam, there should be very little difference, due to the fact the gain difference is only a max of 3db, between them..And considering each “S” Unit is 6 dB we should see a max of less then one “S” Unit

Note..I hope the HEX beam out performs, or equally to the Mosley to be honest..I will just sell the whole system, (2,000) Tower, Rotor and Antenna..And keep my 500 Dollar HEX Beam..(Push up mast / HEX Beam and rotor)

Best

Tom Wright

NN2X



 
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NN2X
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« Reply #27 on: February 15, 2011, 08:10:58 AM »

STAYVERTICAL AND N4JTE

Thanks for your support..!

This is all in the name of fun…To be honest, I hope the HEX Beam performs well…I get rid off the 2000 to 25000 dollar investment (Mosley, Tower, and heavy weight rotor!)! Rather keep the 500 Dollar investment (Mono Band Hex Beam, Cheap Rotor, and Push up mast)!

But I think, if the HEX beam does do well, it might be due that coupling factor, who knows..(From N4JTE)…And again no matter what my results, no one will believe it, any way. It is for me and my location, and all can here me on the AIR doing A / B Tests..

But make no mistake about it..I like quantifying the sales pitch, (On both sides),,,Mosley and Hex Beam..By all accounts this should only be 1 S unit difference, and if so..Great…If not, well, maybe that is why spend the other 2K

You notice, there is already some back peddling tone on the air!
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G3TXQ
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« Reply #28 on: February 15, 2011, 09:57:49 AM »

Tom,

Make no mistake about it, I was verbally told that the HEX beam is equal to the a 3 element Mono bander (3 Element), (By various HEX manufacturers) and does not need to be as high to get effective results.

So, you were not given this information by ALL hexbeam manufacturers as you claimed earlier! If you can confirm that your "various HEX manufacturers" includes those I mentioned earlier, I will speak with them about giving misleading advice.

1. Hex Beam has 3 to 4 dbd of gain over a dipole (Correct)?

Correct!

2. MONO Bander 3 element yagi has no more then 6dbd no matter the design (More then likely 5.5dbd)Correct?

Possibly - depends on the design. Cebik shows designs with just over 6.3dbd gain - I've no idea what the gain of your reference beam is.

3. Each "S" unit is 6dbd on HF Transceivers (Correct)?


No! I think you mean "dB", not "dBd"; dBd would have no meaning in relation to an S-meter. 6dB per S unit is an IARU recommendation, but few Receivers meet it. To quote you from another eHam posting:

"I know many of you, might indicate that an S unit is 6dB, I have not found that in practice, rather I found it to be more like 3db per S unit, just try taking a transceiver with a 100 Watts, and increase to 1000 Watts (Which is 10 DB increase which should only be 1.5 S units (If each Unit is 6 dB, but in reality there is sometimes 3 to 4 S units difference and this is due to the fact that between S 5 and S 9 there is only 3db for every S Unit."

I don't understand why you are now claiming 6dB per S unit on HF Transceivers?



4. Hex Beam works equally well even though at lower heights (In our case only 5ft LOWER)

The variation of hexbeam performance with height is no different than any other horizontal HF antenna.

5. If the above is correct, then when comparing the antennas, MONO Bander Yagi from Mosley at 24FT, and a HEX Beam, there should be very little difference, due to the fact the gain difference is only a max of 3db, between them..And considering each “S” Unit is 6 dB we should see a max of less then one “S” Unit

The difference in height between 19ft and 24 ft is worth about 2dB on a 20m DX path. So, allowing for a difference in Gain of 3dB - making a total of 5dB - I would expect to see somewhere just short of 2 S-points difference using your own figure of 3dB per S-point.

Other things to note:

* The two antennas will need to be far enough apart that there is no interaction between them
* If you want to get within a couple of dB accuracy you will need to take thousands of measurements. When I compared the hexbeam with a reference dipole using A/B switching there were many times the dipole was better than the hexbeam. It's only when you average the results over many thousands of readings you begin to see the underlying trend appear.
* You can only make the comparison on received signals because that's the only way you get control of the measurements.

73,
Steve G3TXQ

« Last Edit: February 15, 2011, 10:00:03 AM by G3TXQ » Logged
K0OD
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Posts: 2910




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« Reply #29 on: February 15, 2011, 10:56:57 AM »

Quote
I don't understand why you are now claiming 6dB per S unit on HF Transceivers?

Dumbfounding, isn't it.  And what engineer [he has posted he's an engineer] seeks "common ground" rather than easily knowable truth?
« Last Edit: February 15, 2011, 11:13:36 AM by K0OD » Logged
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