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Author Topic: What is a good *simple* 10 meter antenna?  (Read 39553 times)
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K1JJ
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« Reply #25 on: October 25, 2011, 02:13:13 PM »

The antenna is not expensive, and looks quite sturdy.  Any ideas?  I'm still wondering if the take-off angle would be too low with the Imax 2000.  It seems to me that the best take off angle would not be 0 degrees - probably more like 30 degrees, but I don't know for sure.

Steve,

Build your own.


Take-off angles for DX:  Let's say "DX" is more than 1500 miles away for the lower bands 160-75M  and 2,500 miles for the higher bands. 40-10M.

The optimum takeoff angle approximately halves when we double the frequency.  This is also dependant on time of day, solar cycle and general conditions.

Generally, for example, from the east coast:

75M: The optimum take-off angle is about 30-45 degrees for Europe and west coast.  (and sometimes higher)
40M : "                                        "          15- 22 degrees       "
20M    "                                        "           11-15 degrees
10M    "                                        "            4-7 degrees
etc.

160M can be a different animal due to horizontal absorption, etc, but will generally require a low angle vertical for real DXing.


The good news is that as frequency increases, stacking antennas become easier due to smaller heights required to get 1/2 wavelength spacing, etc.  Stacking is important to fatten up the lowest vertical lobe and suppress the wasted higher angle energy. Less DX fading this way.  Slightly more gain. The angles given above can usually be achieved with a simple "two or more" stack. The higher the band, the more antennas needed in a stack to push that angle down to those optimum ones listed above.  Also, the booms can get longer which in itself pushes the angle down towards the horizon.

A single antenna at 1/2 wave above ground will give a TO angle of about 30-35 degrees. A simple 1/2 wave spaced two stack will give a take-off angle of about 18-22 degrees. Four ants in a stack give about 7-11 degrees, etc. depending on boom length and spacing. So as frequency goes up, unless the boom lengths are increased, the stack numbers need to be increased to match these lower optimum angles. (or both)

Antennas can be raised higher with wider stacking spacing, and depending on boom length will give lower angles, but at the cost of a sloppier vertical pattern where unwanted higher angles show thermselves.

The stacked lazy H's example in my previous post covers these very low 10M angles well and because the driven elements are spaced a textbook conservative 1/2 wavelength in height apart, the high angle energy is WAY down giving a near perfect low angle lobe, like a big cigar on the horizon... Grin  

Probably the best way for versatility is to switch a stack's phase from zero to 180 degrees so that it covers higher angles only or lower angles only. That way we cover most conditions on a band.

T
 

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« Reply #26 on: October 25, 2011, 02:51:27 PM »

How about the MOXON beam again, only 2-11 foot long elements, ~ 6 foot separation. Thin wall electrical conduit is 10 feet long and might be usable. Otherwise find some bamboo in the yard.
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KX5JT
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« Reply #27 on: October 25, 2011, 05:06:01 PM »

I would say a good simple antenna would be a vertical dipole.  The feed point up at 30 feet would put above a wavelength.
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Steve - K4HX
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« Reply #28 on: October 25, 2011, 08:08:46 PM »

Dats what I have up right now. Some other options in the wings.


I would say a good simple antenna would be a vertical dipole.  The feed point up at 30 feet would put above a wavelength.
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gerry_w1id
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« Reply #29 on: October 26, 2011, 07:33:01 PM »

A coaxial sleeve antenna. This is what I have for 10 meters now. Simple to make and effective. The top of the antenna is up in a tree about 60 feet high. Just remember to add a balun at the bottom to get accurate SWR readings. The only thing about this is it does not weather well. I have tried heat shrink tubing over the antenna. We'll see how that works.
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Dave K6XYZ
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« Reply #30 on: October 26, 2011, 11:18:21 PM »

I'm using the Hy-Gain Hy-Tower on all bands. (the MFJ version)
I was pretty amazed at the ability to have armchair copy AM contacts with the Valiant on 10mtrs.
I've been woking all over Europe with the ol' Junkston!
Probably the most amazing contact was with a G3 on the east side of England.
Not that it was big DX or anything....but he was using a K3 at 15w.
We could hear each other just fine.
This antenna just works great especially on 80 and 40 mtrs.
I put on 90, 70' radials and a DXE radial plate under the base plate.
It really works great with radials. I might have gone overboard with all them radials but what the hell.
I didn't have anything else to do but put out 6300' of wire.
I used the DXE radial kits and stapled the radials to the ground.
I did have to add length to the stinger because all those radials raised the resonant freq considerably.
I checked it the other day with the MFJ 259-B at the base and the resonant point is still 3805 36~.
Not too shabby after 4 years.
I decided not to put up a tower.....if the higher bands are not open I don't need a tower.
If the bands ARE open.....I still don't need a tower.
I will say though it is in the clear on 10 acres....and that helps a lot.
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WB2G
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« Reply #31 on: October 27, 2011, 12:23:25 AM »

A 40-10 meter G5RV 51 foot long and mounted in an attic about 15 about ground got a 57 report in Sweden and Italy,sounds simple and cheap to me.WB2G. Ooops ,forgot ,only 100 watts.
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flintstone mop
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« Reply #32 on: October 27, 2011, 06:41:37 AM »

I'm using the Hy-Gain Hy-Tower on all bands. (the MFJ version)
I was pretty amazed at the ability to have armchair copy AM contacts with the Valiant on 10mtrs.
I've been woking all over Europe with the ol' Junkston!
Probably the most amazing contact was with a G3 on the east side of England.
Not that it was big DX or anything....but he was using a K3 at 15w.
We could hear each other just fine.
This antenna just works great especially on 80 and 40 mtrs.
I put on 90, 70' radials and a DXE radial plate under the base plate.
It really works great with radials. I might have gone overboard with all them radials but what the hell.
I didn't have anything else to do but put out 6300' of wire.
I used the DXE radial kits and stapled the radials to the ground.
I did have to add length to the stinger because all those radials raised the resonant freq considerably.
I checked it the other day with the MFJ 259-B at the base and the resonant point is still 3805 36~.
Not too shabby after 4 years.
I decided not to put up a tower.....if the higher bands are not open I don't need a tower.
If the bands ARE open.....I still don't need a tower.
I will say though it is in the clear on 10 acres....and that helps a lot.
And you know that MFJ 'poor man's' version of the HyTower looks better everyday. But the receive noise levels will increase with vertical polarization. You are lucky to be in a rural setting with 10 acres.
I'm still attempting to get stuff together to build a magnetic loop for 20-10M. My Yagi died and will not take power. And it is too soggy to get a crane truck in my backyard to bring the Yagi down for the second time to see what's wrong. I give up!! It was a bad plan to buy and install a wooden utility pole.

Fred
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Fred KC4MOP
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« Reply #33 on: October 27, 2011, 08:03:54 AM »

I'm still attempting to get stuff together to build a magnetic loop for 20-10M. My Yagi died and will not take power. And it is too soggy to get a crane truck in my backyard to bring the Yagi down for the second time to see what's wrong. I give up!! It was a bad plan to buy and install a wooden utility pole.
Fred

that is what they make climbers for  Grin  Grin I guess you've never been 'coon huntin  Grin
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K1JJ
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« Reply #34 on: October 27, 2011, 12:13:43 PM »

Fred,

Sorry to hear that trap Yagi is giving you trouble again. Especially bad cuz a crane is needed for servicing... sigh.

With a wooden utility pole, it might be best to either add climbing spikes to the pole or construct a "Hazer" of some kind that will raise and lower the Yagi on a rail.


A more "JS" method might be to add an aircraft cable and heavy duty pulley at the top and raise the Yagi up using a bridle on the boom. Then guy each end of the boom to the ground using rope. You would have to manually rotate the Yagi with the ropes, but WTF... I do that now with my 20M and 10M Yagis. Haven't lost a "rotator" yet... :-)

Having the ability to easily service a trap antenna is an advantage. In contrast, a monobander can be made to last 20+ years. Some of my mono-band  homebrew Yagis have been up for 10 years now and still look and perform FB. There's little to go wrong except for the coaxial splices and connections if they are designed well.

T
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« Reply #35 on: October 27, 2011, 07:28:24 PM »

I was going to build a vertical dipole when someone recommended I check the Imax 2000.  I don't know if I could have built the vertical dipole for what the Imax 2000 costs (under $100 including the shipping).  Whatever antenna I would use has to go on top of the 90 foot tower, and therefore mounting hardware, piping, etc would be needed.  So, the Imax looks like a good choice!!

Hopefully, it will work out.  10 meters was very good today.  Worked CA, France and then Hawaii (on AM, of course) and that was with the coax fed 75 meter dipole.
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KC2ZFA
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« Reply #36 on: October 27, 2011, 07:47:49 PM »

is it this Imax 2000 ?

http://www.k3dav.com/solarconimax2000antenna.htm

Peter
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Steve - K4HX
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« Reply #37 on: October 27, 2011, 08:14:12 PM »

The guy's claims are a bit much. I see it for only $65 on Amazon, so the deal gets even better.
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ke7trp
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« Reply #38 on: October 27, 2011, 09:10:20 PM »

Already tested guys. Go for it.  I had one up for years on top of the old 55ft tower.  It would cover all of 10, 12, 15 and 17 with the internal tuner of an FT450 yaecomwood.  Made alot of contacts on that thing.  It bit the dust when a micro storm cell took out the tower. Snapped like a twig. 

Right now I use an A99 I had in the back of a closet for 10 years.  Its at 10 to 15 ft on a makeshift tower. I have been working DX with this and an FT101EE on AM and SSB for a few weeks now. I wish I had the Imax back. However, I dont think the gain would be worth the cost and trouble.   I am going to install my Mosely beam very soon and probably wont need the vertical at all.

C
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« Reply #39 on: October 27, 2011, 10:07:50 PM »

Steve, $65 at Amazon ? why do I see $99 Huh?
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Steve - K4HX
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« Reply #40 on: October 27, 2011, 10:41:24 PM »

I don't see it now. I may have been looking at a A-99 antenna instead. I see some for $65.   Cry
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« Reply #41 on: October 28, 2011, 12:02:25 AM »

Due to the common link between Meth amphetamine use and CBer's, You can sometimes pick up an Imax or other 10/11 vertical antenna very, very cheap. At least in my area. Craigs list is your friend here.



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« Reply #42 on: October 28, 2011, 02:18:43 AM »

I don't see it now. I may have been looking at a A-99 antenna instead. I see some for $65.   Cry

That was the A-99 - a different antenna  Cheesy  The prices seem to be hovering around $100 WITH SHIPPING.  We'll see how it works out.  My 75 meter dipole does work quite well up there for whatever reason.
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Steve - K4HX
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« Reply #43 on: October 28, 2011, 10:51:22 AM »

My modeling shows a simple horizontal dipole is superior to the imax or any other single element vertical by as much as 6 dB. You might want to save your $100.
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K1JJ
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« Reply #44 on: October 28, 2011, 11:04:44 AM »

My modeling shows a simple horizontal dipole is superior to the imax or any other single element vertical by as much as 6 dB. You might want to save your $100.


Agreed!

A single inverted vee dipole at  90' would have many vertical take-off lobes including some VERY low stuff for DX as well as covering higher angles for local USA AM work.

Heck, a dipole is down only about 4-5db from a 3el Yagi. The only real difference is the front to back that the beam has.  TO angle difference is not important in this case cuz the inv vee is so high and will cover the low angles anyway.

The figure eight broadside east and west and ground reflection gives the extra 6db of gain over the vertical, more or less.  Pull those legs out as far as possible to make it flatter and use a coil of coax, make 5 turns -  and some ferrite beads slid over the coax feedpoint, as a balun.

It's hard to beat a dipole.

T

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There's nothing like an old dog.
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« Reply #45 on: October 28, 2011, 11:32:14 AM »

Another idea is to put up a 10M dipole turnstile. This will give a circular omni-directional, horizontally polarized pattern within 3db of itself. (0db = omni)

Get four CB steel whips or aluminum tubes and make two dipoles. Mount them at right angles forming a "+" from top view.  Feed one with coax directly and the second one attached to this same feedline, but with an extra 90 degree coax length.  Beautiful omni pattern with horizontal polarization.  Use a coiled coax balun at each feedpoint.

The omni coverage sacrifices 3db so that it is down 3db from a simple dipole in the simple dipole's favored direction - but in favor of the turnstile, the simple dipole may have 20db nulls off the side.

T

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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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« Reply #46 on: October 28, 2011, 01:24:35 PM »

The trouble with the 10 meter dipole is that is useless for Close in work as most tend to use a Vertical on 10.  At least in my area they do. You also do not get 4 bands without a tuner. 

An 80 meter owl doublet tuned on 10 pretty much just sucks.  Never have I had this beat the old CB antenna.



C



My modeling shows a simple horizontal dipole is superior to the imax or any other single element vertical by as much as 6 dB. You might want to save your $100.
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« Reply #47 on: October 28, 2011, 02:40:52 PM »

I agree for close stuff. My 10M loop is center bottom fed meaning horizontally polarized, and is useless talking to guys with verticals close in. When they switch to beams, I come right up even if the beam is pointed away! Cross polarization is a real issue on 10M LOS.

That said, 10M was open like gangbusters today with Western Canada and Europe is blasting in on the loop at high noon and I even got a good report down south in Cuba on the edge or the loop. I use the 36 foot loop with 6 ft on top and bottom making the sides  12 ft. This vertical rectangle is bottom fed and Use a 4 turn coax balun. The bottom is at 25 feet.

Mike WU2D
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K1JJ
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« Reply #48 on: October 28, 2011, 03:48:18 PM »

Good point about vertical vs: horizontal polarization for close-in "line of sight" type contacts with the locals.  If one does those contacts a lot with mostly verticals used, then certainly it would pay to have a vertical also.  Same thing on 6M and 2M.

The upside is that for any kind of skip work, close-in or far away, the polarization tumbles and will arrive at a random orientation. Thus, either a vertical or horizontal is OK for skip. 

That said, many of the guys I talk with locally on 10M use simple horizontal Yagis, logs or dipoles, so someone with a vertical would have a minor disadvantage there. 

T
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« Reply #49 on: October 28, 2011, 04:36:15 PM »

Steve don't waste your money on crap. $100 you could build a nice beam.
Heck send a coax run up the tower and add dipoles for multiple bands.
A directive antenna will do you no good if you can't rotate it.
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