The AM Forum

Since things seem to be happening on 10 meters, it's time to build a transmitter and get up there.  This gives rise to needing an antenna.

First of all, I cannot put up a beam without changing everything around, so that's out.  I was thinking of either a ground plane (at 90 feet) or hanging an inverted V off the existing feedline (also at 90 feet) that's used for the 160 and 75 meter antennas (I currently have the 160 and 80 meter antennas on the same coaxial line).

Anyway, the key is simple  :D  But effective  ;)  I'll probably be running around 100 watts output from the transmitter.

Suggestions? Ideas? I bet there are a lot of them out there.

Regards,

Steve

As cited in the other thread

http://amwindow.powweb.com/tech/htm/tenmant/tenmant.htm

Several ideas here.

http://www.amwindow.org/tech/htm/tenmant/tenmant.htm


Lots more though. I'm in the same situation. I'm going to put up a quick and dirty dipole and then go from there (probably something directional).

Nothing is simple at 90ft.

Is this going to be a tube rig or SS??

I've used a loop fed with 50ohm coax and a 75ohm 1/4 wave xfmr length of coax from the loop.

Fred

Hang JJ's beam from any tree. Remember, 30 feet is a full wavelength on 10 meters, so really 90 feet is over kill for a horizontal antenna. A vert ground plane at 90 feet would be FB though.


http://www.amwindow.org/tech/htm/10m2el.htm

Steve,

Just to let you know HOW good 10 meters is.. I've heard Tim (HLR) and others talking about it, so this morning just before work I fired up the Flex 1500 (5 watts outpoot) and using a 220 Ft long flat top at 90 Ft, I was able to work 2 Italian stations, the Ukraine, and Germany through modest pileups.. That was within about 10 minutes! The dipole is fed with open wire and tuned by a floating single L network.. Obviously the pattern is skewed, but a ground plane at 90 feet would be fantastic at 100 watts! The point is , if you can couple those watts through a simple T match with the coax to your antennas up there now you would be in business!!

You're 5 and 9 and happy DX my friend!!!  ;D

Steve,

Here's what ya need to do, sonny!
String up a 1/2 wave dipole at the best height you can in any direction you can.
It's a start.

And, for as easy a 10M dipole is you can string up another at 90 degrees somewhere else later.

Remember, I worked Japan last cycle on 29MHz AM with a barefoot Viking 2 and dipole at 15'!

Just about anything will play when the band is open.
12 element log works well
but not as nice as 4 10 element logs stacked and phased.

Add a bit O' tilt and that will qualify for EME...

73DG

I use an 11m vertical 1/2 wave ant  at 40ft. and it works quite well.  But I also use my 75 meter dipole at 50ft. which also works good.

Vertical Dipole, lower half made out of copper pipe, coax up throught the pipe.  Upper half use one of those 102" stingers.  Trim for VSWR you like.

Clamp the copper pipe to the highest vertical object you can. 

done.

Steve, I found this pdf of a 10M Jpole 1/2 wave vertical, built it and hung it from a 50 ft high branch and it works very well.  Easy, quick and maybe better than a 1/4 wave. No radials. Great on the locals too. Trim the wire as needed.http://www.qsl.net/n1lo/10mjpole.pdf (http://www.qsl.net/n1lo/10mjpole.pdf)

I like the idea of the dipole off the existing feedline but it will be directional. The DX is coming in from all over the place, changes every day. Its been crazy...........Larry

Steve,
My first ant I put up when I got my ticket back in 91 was a delta loop up about 30 feet with a 1/4 wave matching stub.  My first contact was the carney islands and then I worked all over the place from there, also with that setup the swr was good across the 10 meter sub band at that point and did not have to use a tuner for that setup.

Good luck with your choice.

Jim

Put an incandescent lightbulb dummy load outside (maybe inside!) with a 100 watts into it and you just might still work the world! :)

This weekend, I might haul a Cantenna dummy load up the tower for fun.  I bet I can log some decent contacts!  Since I have an extra rope and pulley, This would take about 10 minutes.

C

So what did you land up using to get that 5 and 3 report from Ireland Steve?

If you wanna do something like that, don't bother with the Cantenna, use a 100w incandescent lightbulb. They work pretty good. And they dont leak oil..............

what do you guys think of this: http://www.hamuniverse.com/10metercoaxdipole.html ?

Just looks like a variation of the well-hyped bazooka dipole that's been around for years. Claims of low noise - broad-band - better then apple pie - etc.

Steve,

A guy with your talents and motivation might consider something that is not only a strapper, but really cool. You did say, "simple" but hear me out...

You have a 90' tower.  Go out and pick up 8 stainless steel CB whips - or aluminum tubes that are each about 8-9' long.  Then mount each two halves of a "dipole" onto a  ~4" X 8" fiberglass plate using u-bolts.   You now have four sets of  2-half-waves-in-phase for 10M.

Start at the top of the tower and mount the first set and then the other three spaced equally about 17' apart down the tower.  Make sure the elements are insulated from the tower using the fiberglass and additional u-bolts.

You now have a PAIR of stacked lazy H's. (eight elements, four dipoles stacked)  Use open wire and flip the connection so the dipoles are fed 180 degrees out of phase as you go up. The bottom "dipole" connects to the shack with openwire and you feed it with a tuner.

This array will cover both the USA AND Europe with a bi-directional pattern.  I wud have to model it, but the take-off vertical angle would be compressed down in the lower 7 degree area, perfect for 10M.    The horizontal pattern wud be perfect for Europe but maybe a little narrow for USA, but WTF.  Just right for VK and south Pacific.

That stacked system is as easy as pie, but VELY effective, competing with the big Yagi schlongs out there. Remember that VERTICAL take-off angle is everything. That's what stacked antennas are all about.


Heck, if I didn't already have up triple five's for 10M, you can bet I'd put up this lazy H array.  I just turned them with one SW, one NW (USA) and the third towards Europe. We'll see how that works out for now.

T

For those without a 100' tower, but have some trees, try the "Half Square". These offer about 3db gain, are bi-directional, and put out a low angle of radiation when the top is only about 15' off the ground. This is a huge bang for the buck spent. Here is one similar to what I use:

http://www.antennasmore.com/halfsqua.htm

Fed at a corner it is 50 ohm feed. Length is 17' with two 8' vertical drops.

This antenna is a candidate for a 'Big Box Store' special where the materials should be very low cost. Here is one case where one was home brewed:

From Dick K2HT #3727 - 10-Meter Half Square Antenna
Scroll down near the bottom:
http://naqcc.info/newsletter_140.html


Jim
WD5JKO

I like the simplicity of the 10M J pole.......The dimensions given are close for a good match? OR do we play with the 450 ohm stub to make the match??

And Tom you should be whirl wide with your array of aluminum.

Fred

F,

I've been looking at the Cebix site. "They", (he's dead), have a lot of antenna ddesign and modeling  information. He has a section primarily for 10m operations.

http://www.cebik.com/

I've been toying with the idea of  "A Vertical Doublet for 30-10 Meters".

http://www.cebik.com/content/gp/v20.html

As far as "JJ" and his 4 half waves in phase, I hate him and his al uminium farm. Deeply.


klc

I added a 16 ft center fed element in parallel with my 135 ft. doublet.  I feed it with a tuner and balanced window line.   According to EZNEC the pattern on 10M is almost the same as a regular dipole.  I used some PVC pipe cut up into 6 inch pieces, slotted the ends and used them as spacers with the regular 135 ft antenna.      I did this years ago as suggested by K1JJ, now I can finally use it.

Tom, good suggestions!

If I get really serious, something like that would be the ticket.

I found something a lot of folks seem to like - the Imax 2000.  It's a 5/8 wavelength vertical.  How they get away with no radials is questionable - although there is a "radial kit" one can get as well.

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... ;D  

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
 

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.

I would say a good simple antenna would be a vertical dipole.  The feed point up at 30 feet would put above a wavelength.

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

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.

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.

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.

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

that is what they make climbers for  ;D  ;D I guess you've never been 'coon huntin  ;D

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

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.

is it this Imax 2000 ?

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

Peter

The guy's claims are a bit much. I see it for only $65 on Amazon, so the deal gets even better.

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

Steve, $65 at Amazon ? why do I see $99 ????

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

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.

That was the A-99 - a different antenna  :D  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.

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

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

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

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

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

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.

I heard you on 29.050 this afternoon Steve.  20 over 9.  Whatever you have is working very well. 

Ahhh --- it would have been great to talk with you.  That was the 75/160 meter antenna (2 dipoles on 1 feedline) up at 90 feet.  Output power was maybe 80 watts.

10 meters was really good later in the afternoon - steady.  It was a bit up and down earlier.

Yes it would have!  I will be back on tommorow around 5:30 -6:30 your time (an hour ahead).
Whoever you were talking with here in 5 land, of course I couldn't hear but they must have been making some buzzard txmissions!  It was quite a few minutes between yours.   I didn't want to interrupt.

That's one bad thing about 10 meters, not easy to get into a roundtable. 

Hey Steve....I heard you too on my 'poor man's' MFJ Hy-Tower.....HA....what a crock....
It turns out that the MFJ updated version is a hellova lot better than the Hy-Gain version ever was. You were very loud here just North of Tulsa.
Some of my elmers back in the late 50's had them. They are a lot quieter if you put a good radial system on it...so I did.
John....Steve was working my buddy Don WB5HAK over in Duncan, OK just South of OK City. He and I yak on the Collins net every tue and thurs.