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Author Topic: 2 X 2 X 2 40M Yagi stack - progress pictures  (Read 36553 times)
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Patrick J. / KD5OEI
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« Reply #25 on: August 27, 2009, 10:37:37 PM »

That's a real nice antenna there, I'm a little jealous.
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« Reply #26 on: August 27, 2009, 10:38:58 PM »

Well now that I've recovered from being in awe, thanks for sharing the photos and construction details Tom; the chokes and feedpoint detail sure wwew interesting.  I'd say I picked the right guy from whom to follow antenna advice.  I'll enjoy reading a description of how they played into Europe after you've been operating for a night or two.   I was a bit surprised to read that you are using the gas dielectric heliax.  Are you pressurizing it with nitrogen or pumping in dehumidified air?  I sure hope ur wx continues--looks pretty good in the photos.

73
Rob  K5UJ  
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« Reply #27 on: August 27, 2009, 11:09:33 PM »

There's a reason we call him Master Vu!   Wink
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K1JJ
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« Reply #28 on: August 28, 2009, 12:08:21 PM »

[
Yeah, no more crazy antennas for me Tom.

The 6M CC's are on 4' booms, this is a collinear just like the old 2M ones of the 60's. Each bay is a full wave reflector and a full wave DE insulated and fed in the middle. That equals 4 el. Each bay is 1/2 wave spaced. I will setup to select each 16 el group or all 32. It has a wide elevation lobe as well as a huge azimuth lobe. Great for aurora and meteors plus contesting. I'll probably have the 20 el yagi array switched in also or maybe use one amp for the collinears and another for the yagis....at the same time. The gain should be impressive Grin

Carl
KM1H



OK on the collinear 6M beams, Carl.  Yes, I remember them now. I almost constructed the same thing until Chuck told me of some tests run by a guy who first tried 2el  ½ wave Yagis and then tried the full wave els. He felt that on 6M, supporting the els at their high impedance points was lossy thru the insulators and canceled out the extra ~2.5db of gain.

I took this advice and made an array using  ½ wave Yagi eles supported at their center low impedance points instead. I wonder what your opinion is of this? 

Here’s a pic of the 6M array. It faced NE or SW, switchable via coax.  It started at 190’ and went down to about 55’.

BTW, I compared it against my 7el  6M Yagi at 190’ and saw little difference into the W3/W4 area. I know they were working and phased correctly.  I wasn’t impressed enuff, so might try some form of fixed array using  two or three  Yagis with slightly longer booms in various directions. As you can tell, I hate rotators, but might make an exception on 6M and use my prop pitch for one big MoFo. The jury is still out. Even though 6M is a gay band, I still like the magical action there… Grin


Check out the LONG boom triple 6M stack too. All homebrew.


Rob/UJ:  The hardline is just regular stuff - no gas. It uses disks every 3" to support the center conductor.

T


* 6M 8-bay 56 element array.jpg (237.3 KB, 1280x960 - viewed 1112 times.)

* 6M triple 33 el Yagi stack.jpg (367.88 KB, 1280x960 - viewed 1789 times.)
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« Reply #29 on: August 28, 2009, 01:18:49 PM »

Wow Carl,
you bought Chuck's ant. I saw it on the ground just after he rebuilt it.
 What a beast to cover such a small frequency range.
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« Reply #30 on: August 28, 2009, 02:14:17 PM »

Nuthin' like the sight of the sunlight reflecting off of aluminum in the morning sky!

Great antennas Tom!  I once had a 60' boom behemoth up for 20 and 10, along with 4 elements w i d e spaced for 15 all on my 80' chunk of microwave tower.  Used 4" mast and turned it with a large prop pitch motor.  Unfortunately, a tornado passed over and high winds aloft wound my 60' boom around the tower.  Never was able to replace those antennas...just too much of a job to put them up and maintain them.  Sure worked good though!  I used to look for pile-ups to exercize my antenners...didn't always get thru right away, or first in line, but it usually didn't take long to be heard.  I always believed in the words of wisdom:  "Don't worry too much about the radios, spend the money in the back yard!"   Grin

73,  Jack, W9GT
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« Reply #31 on: August 28, 2009, 08:41:58 PM »

K1JJ PRESENTS MR RADIO STARRING TOM VU   Shocked AT THE MICROPHONE  Grin
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« Reply #32 on: August 28, 2009, 09:48:44 PM »

Nuthin' like the sight of the sunlight reflecting off of aluminum in the morning sky!

Great antennas Tom!  I once had a 60' boom behemoth up for 20 and 10, along with 4 elements w i d e spaced for 15 all on my 80' chunk of microwave tower.  Used 4" mast and turned it with a large prop pitch motor.  Unfortunately, a tornado passed over and high winds aloft wound my 60' boom around the tower.  Never was able to replace those antennas...just too much of a job to put them up and maintain them.  Sure worked good though!  I used to look for pile-ups to exercize my antenners...didn't always get thru right away, or first in line, but it usually didn't take long to be heard.  I always believed in the words of wisdom:  "Don't worry too much about the radios, spend the money in the back yard!"   Grin

73,  Jack, W9GT

Hi Jack,

Those 60' boom 10M and 20M Yagis must have been tremendous.  It’s not easy to get one of those antennas tuned correctly and erected, but what performance!  The long boom even lowers the take off angle to boot.

I believe in focusing efforts into a FEW antenna systems and having lots of fun working with optimized stuff.  Being all things to all bands is near to impossible hardware and time-wise.  For example, I’d rather spend the time building up a big array for Europe on 75M and be able to hear and work stations that most cannot – rather than  spending the time on generalized antennas like a large omni-directional vertical and radial system that’s designed to work everywhere.  I mean, if wanted to work everywhere with average results, I’d just make a cell phone call….     Hello, Pascal? You’re 59 again tonight on the telephone. Reply: “Stop calling me every night you idiot!”   Grin

I’ve decided to eliminate a few bands and directions here to have the room for all-out antennas on a few bands in certain directions. I took down my 160M antennas and also 15M Yagis. (and 6M Yagis for now)  I find 160M OB transmissions too much to handle – and the 160M DX into Eur is sparse on ssb. CW is fun, but quite lonely.  15M interacts terribly with 40M, so that was an easy one to eliminate.

But when I get on 75M or 40M I have three major directions with f-b and gain. 20M uses a pair of stacked 60’ boom Yagis that is presently on Eur but can be rotated anywhere else using the Armstrong method.  10M uses a triple stack of 5el Yagis. That’s it. I have lots of gaps in band coverage, but the ones I do have are like getting into a dragster and popping the clutch. It’s a blast to call CQ for Europe and be able to hold court with many stations calling. It’s usually the USA chasing the DX. I like to give them some fun for a change. 

I also like to give out very specific S-meter reports. Hams love to know how they stack up against others.  Telling everyone they’re “59” is a joke. I always watch the meter carefully and give out an exact S-meter report. This increases the pileup and gives the DX something to compare with.  Pausing to listen for mobiles and weak 10w UK foundations stations or weak Russians adds a flavor too. Picking out the weaker ones in a pileup is fun and gives everyone some action.  I just love working the Europeans and hearing their diversity. The Russians are crazy about radio and very enthusiastic.

One of the most effective stations and most skilled AMer/DXer is WB3HUZ. He’s put up a very well-tuned pair of 40M delta loops that kick ass. With his beverages and K9AY loops he can hear very well. I heard him on 75M the other night working a pileup in the static just using a dipole at 80’. He does better than some “big guns” on that band. Wait til he gets up his 75M phased dipole array.  His QTH’s lake, drop off and swamp in front of his antennas seems to help a lot.

Anyway, mixing up the AM activity with working DX keeps it fresh. It really pays to have two or three focused activities in radio to keep the interest up. Hanging on one freq night after night with the same group is a great way to get into trouble and burn out…

BTW, here’s a pic of my 20M Yagis at 50’ and 100’ on the other self supporter. It’s amazing what I hear outa Europe with these, even on a quiet band. Listening on lower reference dipoles is like unplugging the antenna sometimes. These Yagis feature insulated elements sitting 3” above the boom - using fiberglass for each. This makes it easier to use precise element lengths that are not affected by the boom currents, thus a better tuned Yagi..   These are 300 pound Yagis. One day Huz, INR, JN and I almost got a hernia carrying them into position. I always try to get a little work outa them when they stop by…

Been very busy for the last year on many projects, mostly non-ham related, so haven’t been on the air much. But want to get active again this late fall. I really enjoy working coast to coast on 75M AM and hope to catch you on then, OM.

73,
T


* 20M 5el Yagis, insulated elements.jpg (140.96 KB, 1280x960 - viewed 764 times.)

* 20M 5el 60' Yagis.jpg (33.82 KB, 480x640 - viewed 866 times.)
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There's nothing like an old dog.
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« Reply #33 on: August 29, 2009, 10:11:56 AM »

Tom, Chuck and I spent many hours here and at his place going over computer modeling of various 6M fixed arrays. I believe we both agreed that a stack of 3 el yagis as tall as possible was the most gain producer combined with a broad azimuth. We then retired to various Mexican restaurants, with a few like minded hams, that we were often escorted out of Grin

I went with the collinears since they were historic as well as free Grin  I was also concerned about the insulators at the HV points. The original ones looked like some form of ccompressed paper, all pulpy from decades on the ground. With new ones machined from black Delrin no heat can be felt after running 1200W for a few minutes into a single FW element and matching stub. Remember that there is virtually no current at those points, just lots of voltage and the dielectric strength of the Delrin proved more than sufficient. Split this up into either 4 or 8 driven elements and the effect is far less. I never noticed any detuning in the rain either and I always monitor screen current plus a dedicated in-line Bird.

My comparison antenna at that time was a 6/6 Hi Gain at about the same center height. Gain was about the same most of the time with one or the other having the edge at times into EU. On relatively local stuff, Lefty, K1TOL up in Central Maine, reported the collinear far superior and dubbed it the bedspring on his next visit. I designed the improved, and sold him, a 8el Wilson which proved to be a real kick ass antenna.

I next used YO to model the Cushcraft 6 el Boomer I picked up at Deerfield, or wherever it was that year, added 2 elements, and settled on a solid 13dBi  gain and a 35-40 dB F/R over the full 180*. YO reported gain was .1 dB from theory. My problem with the collinear was the 12-15 dB F/R and many noise sources to the back masking weak DX. With the 8el replacing the Hi Gains, the gain was again about the same but band noise was so quiet I sometimes thought something opened up in the feed.

As an aside I later took a serious look at the Hi-Gains, improved the pattern a lot and got rid of that almost a dummy load matching arrangement they used. The T Match is the only thing I will use.

With the collinears going to the other tower which is another 150' from the power lines and far above everything Im hoping the noise will be tolerable and that the blanker can handle. Im now pointing at the noise. With the noise being vertically polarized and at low angle Im keeping my fingers crossed.

Im lost without antennas that rotate, either electrically or mechanically. My interests are mostly DX and some contesting so 360* with lots of gain is imperative. Im not going as crazy as before and yagis will be limited to 2 per band on HF; no more 19 yagis on just the traditional HF bands 40-10M. Long path on 80/40 can vary from over central EU to the southern tip of Africa depending upon what the propagation gods deal out. On 80/75 a dual element inverted vee at 180' often blew thru the 4 sq and 2el yagi bunch. This is at 1200W. With the pair driven at right angles as mentioned elsewhere on here I had 360* directivity with a mix of V & H polarization and the Beverages indicated the path in use. Working the same EU or JA night after night bores the hell out of me and I'll often ignore a band for weeks at a time unless something really good pops up like the time I worked 3 Zone 23's on 80/75 the same evening to complete the 1st W1 5BWAZ once the QSL's arrived.

Happiness is pushing myself and the equipment to the edge at times. Ive also done substantial DXing with QRP, even on 160. But Chuck's 3 el 75 was a bit too much. If I had put it up it would have been with the 80/75 switching mod.

Carl
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John K5PRO
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« Reply #34 on: August 29, 2009, 02:19:37 PM »

JJ, thanks for posting all this inspirational material on how big gun's do it, caw mawn. Very impressive.
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« Reply #35 on: August 29, 2009, 04:57:58 PM »

Carl,
Very interesting on the various antennas you've tried. I always find others' personal antenna experiences interesting.  I've also experienced a fair amount of noise with the 8-bay 6M Yagi stack. It sure had a lot of phasing coax to install. OK on the high quality insulators you used and the heat tests. Looks like it worked out FB in the end.

I did some modeling, thinking and axed a lot of questions of the gurus about the best sporadic E 6M antenna. Seems the best angle for that mode is about 20 degrees take-off. So I built up an 8-bay bunch of 3el Yagis on a double H-frame to be mounted about 20' off the ground. Killer medium-angle antenna. I never put it up, but thought that wuda been a great bunch of fun, to work E with an advantage. But most DXers are into F2 prop, so I'll look into something higher and longer boom I guess.

What is a pair of 75m inv vees driven at right angles to get a switchable 360 degree coverage?  What is the original config too?

Yeah, K1TOL is big up there wid that triple long boom 6M Yagi stack and the rotating tower. I saw his modeling work done by WX0B and it looked impressive. He hears pretty well as I found listening to him.


Well, it's almost September now and I guess we'll be winding down the antenna work pretty soon. I'm all antennaed out so after these 40M Yagis are finished, I might do a few minor antennas more and then call it quits for the season. I expect to make good use of the 75M deltas  NE/SW and the new 40M antennas this season.

John/Pro:  Glad you found the info valuable, OM. I find it helps me too to read what other guys are doing. HUZman's great success with his 40M delta loops spurred me on to do something with the Yagis.  I was satisfied with a 7el wire Yagi at 70' until I noticed he was starting to kick my ass on 40M into Europe. He's getting nervous now and looking for a 100' crankup tower to hang some rotaries.  Grin

T




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« Reply #36 on: August 29, 2009, 09:07:12 PM »

I think everyone on 40 meters is worried! The rumors are out that a big tri-headed slapper will soon be descending on the band. The mud ducks are scurrying.


* ducks.jpg (210.1 KB, 800x500 - viewed 732 times.)
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« Reply #37 on: August 29, 2009, 10:24:01 PM »

Tom, Ive explained that 75/80M antenna before, maybe even in Deerfield.

Any way its just 2 antennas at right angles and feeds tied together. One is cut for CW and the other for the SSB DX window. Gives a nice low VSWR on both. Both sections take power on either operating end since the VSWR means nothing to a radiator. No phasing line as with a turnstile which turns it into a cloud warmer. Since an inverted vee is horizontally polarized broadside with a vertical component endfire I wind up with both components in 4 lobes each. Over real ground thats close enough to 360* for me and it works as expected. I told Randy, K5ZD about it when I was still a YCCC member and he tried it and had similar results at a much lower height...90' I believe. It was subsequently written up in Scuttlebutt. Since 80/75 at greyline usually starts at a very high angle from West to East, and the reverse at sunrise, (the infamous one way skip) around 45* or so and then lengthens out having a wide elevation pattern works well. The other end of the path is the reverse and until the angles become somewhat similar or lots of power is used its like talking to yourself. I can track the changing band with the Beverage as I add or subtract sections, peaking around 2300-2400 local and slowly reversing towards EU sunrise.  Thats under normal conditions. All bets are off when the auroral zone pushes EU over Central Africa or we are inside it. Im more prone to that and the dividing line often seems to be the Mass Pike!

If I get time I want to put another pair 130' lower (at 50') and do an lower/upper/both switching. Should be interesting.

K1SG, Steve Gilbert, in Hopkington, MA has a 150' rotating tower with four 11 el for 6M and does rather well. All I want is the thrill of a long JA run on 6 with the new array next year. CW of course.

Keep us posted on the 40M system, thats probably the biggest in the USA??

Carl
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Steve - WB3HUZ
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« Reply #38 on: August 29, 2009, 11:07:41 PM »

That antenna has big lobe at 90 degrees elevation, only 3 dB down from the main, low angle lobes at 23 degrees. I wonder what effect that has? I see nulls at the medium angles.
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« Reply #39 on: August 30, 2009, 08:50:21 AM »

Which antenna?

Carl
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Steve - WB3HUZ
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« Reply #40 on: August 30, 2009, 06:57:54 PM »

The inverted V at 180 feet.
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« Reply #41 on: August 30, 2009, 09:28:04 PM »

How are you modeling it?

Carl

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Steve - WB3HUZ
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« Reply #42 on: August 30, 2009, 09:44:29 PM »

Top at 180 and ends at 130. Took a guess as the end height. Maybe your ends are higher/lower?
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« Reply #43 on: September 01, 2009, 03:08:35 PM »

The ends wont affect that lobe. It sounds as if you are feeding it as a turnstile.

Try modeling a simple dipole horizontally and as an inverted vee.

I used MN and NEC Wires and it looked as expected.

Carl
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Steve - WB3HUZ
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« Reply #44 on: September 01, 2009, 09:24:28 PM »

Just a single dipole at 150 feet. It has a big high angle lobe, null at medium angles and main lobes at the lower angles. This is exactly what I would expect for a horizontal antenna more than one-half wavelength above ground.


* highdip.gif (42.47 KB, 604x602 - viewed 671 times.)
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« Reply #45 on: September 02, 2009, 03:24:30 PM »

OK, that is as expected and I misread your prior thinking the high lobe dominated.

That high lobe is extremely useful when conditions appear to favor ducting phenonoma on long DX paths, primarily trans equatorial. Another side benefit is keeping locals at bay Roll Eyes

One extreme ducting example was the February 1990 3Y5X Bouvet DXpedition. I had just moved in here and had no antennas up. I quickly tossed up a 58' 25G with a 4el 10M on top and a full size 160M inverted vee about 5' lower with the ends about 4' above ground. Just a concrete base plate on the frozen ground and 2 levels of guys wrapped around pine trees in a somewhat 120* pattern. That tower is still there with no changes!
Id worked them earlier on 10 and when they showed on 160 the pileup was humoungous by the time I got on.
Figuring this would be an all nighter I sat down and sent my call the usual one time.....and he came right back!

Later on I worked the operator from his home and he asks what the heck I was running. He then told me I was at least 10dB above everyone including guys he knew were running 10dB more power. His comment went something like: "I was trying to get a complete call from anyone and tuning the full width of the pile and all of a sudden you exploded out of nowhere"

Carl
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Steve - WB3HUZ
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« Reply #46 on: September 02, 2009, 04:12:08 PM »

As the old saw goes, "You can never have too many antennas."

Great story and a lesson to all. You don't necessarily need to have prodigious antennas to work DX, maybe even lots of it. Sure big antennas help but they aren't absolutely required. Sometimes timing and/or patience are just as important. Some guys have over 200 countries on 160 meters with nothing more than a 30 foot high dipole. Dive in, the water is fine.
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« Reply #47 on: September 02, 2009, 04:14:21 PM »

I worked over 100 on a vee beam
Every Dog has his day
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