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Author Topic: One - Do- Tree... Tests with the 2x2x2 40M Yagi stack  (Read 202717 times)
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WA1GFZ
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« Reply #200 on: September 25, 2009, 02:33:13 PM »

My simulation shows best performance as a folded dipole with a foot spacing between base and apex. I have not tried to drive it yet. This gets the average height way up
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« Reply #201 on: September 26, 2009, 12:32:49 AM »

Tommy, for what it's worth, this morning when you switched to Cal you were S3 vs S9 to S9+10.  The F/B is FB.
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« Reply #202 on: September 26, 2009, 01:09:21 AM »

Tommy, for what it's worth, this morning when you switched to Cal you were S3 vs S9 to S9+10.  The F/B is FB.

Hi Johnny!

Was this on 75M?   (Steve and I held court on both 40M and 75 tonight)

If the S-Meter is accurate, that's about 46db f-b...  Grin   That's the 2el delta loops at 190', caw mawn.

Are you ready to try a test? We can possibly try it tmw night local time on 40M.

T
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« Reply #203 on: September 26, 2009, 01:14:52 AM »

Yeah, 75, 3800 KC.

My laptop running my Skype server has crapped out.  Hopefully I'll fix it today (the boot record got corrupted).  I can still get calls on Skype using this computer but it's not convenient to get to the radio room with the phone til I get the other laptop fixed.  I'll let ya know and PM my phone # (it's a 301 area code).

The guess meter on that TS-50 is *fairly* accurate, as I recall, and integrates the peaks pretty well.
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« Reply #204 on: September 26, 2009, 11:28:09 AM »

anybody look at loops spaced 5 feet apart. I'm seeing a nice VSWR darn close to 50 ohms with a reflector / driven element. FB not super but ok but gain 10 dB. Thinking of a second driven loop behind the reflector for the other direction....then tune it as a second reflector. The thought is kick out the bottoms of the loops to get more spacing if required
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« Reply #205 on: September 26, 2009, 08:35:08 PM »

Tom, I saw 20-30 dB F/B last night on the loops. That's quite high considering the distance. The EU's were seeing in the mid-20 to 30 dB on a couple. That muddy water slapper is talking!
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WA1GFZ
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« Reply #206 on: September 27, 2009, 05:17:52 PM »

Well, dialed in the driven dipoles and nice VSWR but FB not great. Worked a few stations but doesn't look all that great. Maybe it is time to move on to something different. Yes a driven array can demonstrate nice FB but I'm starting to think that is about it
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K1JJ
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« Reply #207 on: September 28, 2009, 10:16:02 AM »

Well, dialed in the driven dipoles and nice VSWR but FB not great. Worked a few stations but doesn't look all that great. Maybe it is time to move on to something different. Yes a driven array can demonstrate nice FB but I'm starting to think that is about it


OK Frank,

You will probably end up with the parasitic tuned switchable stub method that both Huz and I use.  Take a look also at the extended base delta loops I posted a few posts back. If ya want big f-b, you either need a 3el Yagi or the 2el delta loops. A 2el Yagi won't make it F-B wise.

 Going sailing wid Yaz today. Last good day of year for getting wet and windy, I think.  Great night on 75M and 40M last night. Worked over 150 stations in pileup on both bands. Lots of Russians and some middle east on 75M too. The angles are very LOW lately on both bands.  Hope  you get something going soon, OM.

T
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« Reply #208 on: September 28, 2009, 12:41:25 PM »

Tom, I have a nice simulation of a 10 foot tall delta at 10 foot spacing that looks great into 50 ohm coax with a stub on the reflector. Third element is funky. I might just do two element fixed direction. I have not been able to simulate HUZ bandwidth yet, I'm tigher. I have the simulation set up to tune the stub length and it ended up within 6 inches of HUZ loops. The 2 element dipoles give me a bit better perfromance so far. 20 foot spacing short deltas with points up are not as good as dipoles so far. 
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K1JJ
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« Reply #209 on: September 28, 2009, 09:44:08 PM »

You're on the right track now, Frank.

Do whatever it takes to get a f-b of 25db+.  Again, a 2el simple dipole Yagi won't do it.   I think delta loops at the top of your tower (68'?) is the answer.

BTW, paper wasps like to fly around and circle towers for some reason. They do it to my towers all the time. It doens't necessarily mean they have a nest up there, so don't be afraid to climb to the top. If they do, they are usually pretty docile creatures anyway. (not including hornets)


Check out Yaz's excellent adventure here:

http://amfone.net/Amforum/index.php?topic=21375.msg152014;topicseen#msg152014

T
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« Reply #210 on: September 28, 2009, 10:27:00 PM »

Tom, Best FB on the dipoles was about 16 dB. Right now I have a 3 element delta loop running simulation for the past hour. FB 25 to 30 db with 10 dB of gain. Tuned stubs on the front and back with center driven. All on a 20 foot boom. Waiting for it to stop so I can change to 70 ohm feed line 50 a bit low. Input Z running around 90 ohms. Still searching for the right variables. It is tuning both stubs front and back loops then tuning the center  so plenty of stuff to tune.
If it works I'll be able to swap the pattern by swapping the two stub lengths.
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« Reply #211 on: September 29, 2009, 09:12:57 AM »

Tom, HUZ, Frank....

Have you guys looked at the "triangle" or pyramid variation of the two full-wave loop antenna?  I have an old Ed Noll antenna book: 73 Vertical, Beam, and Triangle Antennas.  In it are several versions of the loop and multi-element loops and also a triangle or pyramid version.  Basically it is nothing more than two delta loops with the apex of both very close to each other at the top (opposite sides of a tower or mast)....then the bottom legs and base of the loops are pulled out 1/8 wavelength from each other on the bottom.  The effective spacing then varies from a couple of feet or so at the top to 1/8 wave at the bottom.  Seems like this might produce a higher angle of radiation off the front, but it is mechanically much easier to accomplish since the boom would not be required and a common top support could be used.  I wonder if you could model it and see how it looks?

Tom, another interesting thought for an experiment with the 40 M yagis would be to extend a 1/2 wave length of wire from the tip of each element...let it hang down and connect to the tip of the corresponding element of another yagi below it.....resulting in a two element two wavelength around bisquare.  Looking like a really big (double sized) quad.

I thought about doing something like that with 20M yagi elements and making a full-sized 40 M quad.  The advantage of this over the diamond loops would be a higher center line of radiation.

Anyway...lots of fun.  I hope to get the second diamond-shaped loop up here shortly....we'll see how it works.  I now get really great reports from Europe and manage to break thru the east coast curtain fairly well with the single loop.   Grin

73,  Jack, W9GT
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« Reply #212 on: September 29, 2009, 11:32:37 AM »

Hi Jack,

OK on all the loop info. Interesting ideas.  Yes, the "no boom" deltas oughta work. I have even seen Yagis model out well where the elements are not square. They worked on their average distance to produce the pattern.  Though with Frank already putting up a boom, I doubt he'd bother to try it now.  But others without a boom may. I've also seen a variation- on 160M, a four square that had the wires start at the tower and pulled way out. It modeled out pretty well.

BTW, I heard you on ssb a week ago working a Euro on 40M.  You sounded excellent!  You had punchy, well tailored audio and sounded like a cross between a relaxed contester and sophisticated DXer.  Very nice ssb presence, OM.  Hope you get the second loop working.

After I came back sailing yesterday, it appears the high winds rotated my top 40M Yagi from perfectly horizontal to slightly vertical. I obviously didn't have enuff clamping on the boom to keep it from twisting. I figgered the overhead trussing wud stop any longitudinal rotation, but NG.   Now gotta fabricate up three new brackets to clamp another part of the booms to the tower- on all three Yagis. This will also keep the beam from rotating in the horizontal plane.  It's good it happened now, cuz the winter 50mph+  winds wuda messed things up for sure and I'd be stuck all winter looking at it...  Angry   So gotta get some new SS 3.5" U-bolts and go to work on it. I thought I was done climbing for the season too.

T
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« Reply #213 on: September 29, 2009, 12:45:59 PM »

Jack,
I ran out of steam last night and didn't get a chance to set the bottom of the outer loops spacing as variables so the program would find the right distance to move them away. When I stopped the the gain was around 10 dBi with over 25 dB of FB. Also the input Z was high enough that a quarter wave of 70 ohm coax or 70 ohm feed would produce a nice match. The bandwidth of the antenna is fairly tight though, unlike the HUZ design. I'm thinking real world coax and stub losses give a wider bandwidth. It looks like adding a third element improves the FB but not by a lot. Bottom down loops do not seem as good as flat side up. Nothing like simulation and a pulley system to make life easier.
Tom Vu needs to build a Joe Hunt magneto clamp so the beam doesn't turn.   
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« Reply #214 on: September 29, 2009, 08:24:04 PM »

Sounds like a good model, Frank.  2el shud be enuff for a good F-B on the deltas.

Here's a picture of the top Yagi with the spun boom.  I be on the way to vertical polarization like the good buddies.   I found some steel angle and gonna make up the additional side arms with THREE 3.5" u-bolts to grab the boom for each Yagi. That oughta do it.

A good eye will see the top Yagi is off by about 15 degrees or so.  It will probably get worse if I do nothing.

T




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« Reply #215 on: September 30, 2009, 09:00:33 AM »



BTW, I heard you on ssb a week ago working a Euro on 40M.  You sounded excellent!  You had punchy, well tailored audio and sounded like a cross between a relaxed contester and sophisticated DXer.  Very nice ssb presence, OM.  Hope you get the second loop working.


T


Thanks very much for the kind words Tom.  In a former life, I was a very active DXer and, to a lesser degree, an avid contester.  My former call sign: N9GT was fairly well known in those circles, although I never quite reached the honor roll.  After realizing that, for a number of reasons, I could not continue to be as commited or as competitive as I wanted to be, I became much less involved in those endeavors.  I still really enjoy working DX and occasional contests, but my main interest for the past several years has been AM and vintage gear.  I also really enjoy building amplifiers and playing with antennas.  I have certainly enjoyed following your exploits in those areas.

I wish I could physically meet the challenge of running up and down my tower like I used to, but I don't do much climbing anymore.  That is one reason I was searching for a way to easily hoist loops and/or other stuff up and down, without having to climb.  I really enjoy playing with the loop antennas on 40.  It is much easier to be competitive on that band if you can get anything bigger than a plain old dipole working.  Hopefully, will get the second loop working soon.....we will see how much difference it makes.

73,  Jack, W9GT
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« Reply #216 on: September 30, 2009, 03:10:20 PM »

Tom I wonder if you should put some rubber between the clamps and boom. Say rubber from an inner tube?? Something to add friction???
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« Reply #217 on: September 30, 2009, 03:42:40 PM »

Tom I wonder if you should put some rubber between the clamps and boom. Say rubber from an inner tube?? Something to add friction???


Hmmm.. I'm not sure if adding a wafer of rubber will make it slip more or hold it. It will at least have some flex to it.

I climbed up there today and took measurements so I can make up the sidearms tonight. As the wind blew the booms around I could see that it definately needed some additional bracing. The horizontal side to side motion was held only by a few inches of the center bracket - no leverage. The overhead trussing did nothing in this plane.  The addditional side arms will make it real solid by adding leverage and ALSO prevent boom twisting from the long elements.   I think the three additional boom u-bolts shud do it.

You shud not have the same problem cuz the loops will guy it for side to side motion - plus you have no element twisting motion to worry about.

BTW, what is the antenna dajour ?   Grin   Have you finalized a model to put up yet?




Jack - FB on the contesting and DXing in your prior lives.  I truly enjoy getting on when there is bad static and nobody on cuz they think cornditions are bad. Then with a few CQ's, Europe comes alive creating a pileup for the next few hours. That is such a thrill to me, especially doing it on 75M! Then the Euros start saying conditions must be great... Grin  Maybe we can work in tandem in the future.

T


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« Reply #218 on: September 30, 2009, 04:07:10 PM »

Tom,

If you could drill a hole thru the boom without weakening it too much you could effectively pin the support arm to the boom preventing any twisting.  I think the rubber under a clamp might deteriorate, especially with New England wx condx.  Stainless muffler-type clamps are pretty strong and with a pin/bolt thru the boom fastened to a piece of angle material also fastened under the clamp nuts...it would be really strong.  I did something like that on the center support of my big (60' boom) 20/10M yagi.  I used really heavy thick-wall tubing for the center portion of the boom.  It had overhead truss-guys on the boom, but had problems with it twisting...that was my solution.  Worked great until a tornado passed over and wrapped the boom around the tower.

73,  Jack, W9GT
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« Reply #219 on: September 30, 2009, 04:29:17 PM »

Tom,

If you could drill a hole thru the boom without weakening it too much you could effectively pin the support arm to the boom preventing any twisting.  I think the rubber under a clamp might deteriorate, especially with New England wx condx.  Stainless muffler-type clamps are pretty strong and with a pin/bolt thru the boom fastened to a piece of angle material also fastened under the clamp nuts...it would be really strong.  I did something like that on the center support of my big (60' boom) 20/10M yagi.  I used really heavy thick-wall tubing for the center portion of the boom.  It had overhead truss-guys on the boom, but had problems with it twisting...that was my solution.  Worked great until a tornado passed over and wrapped the boom around the tower.

73,  Jack, W9GT


Jack,

Yes, pinning is always a good idea. I've done it to all my elements, including the 40M Yagis.  I didn't do it to the boom cuz I wanted the flexibility for exact adjustments.  What I'll do then is drill the new steel sidearm bracket for a future pin, but not add it unless I have to.  If needed later, then I can simply drill thru the aluminum boom while up on the tower at some future date..  The boom is only 17' long and the center section is 3.5" 1/8" wall, followed by 3"  extensions. Pretty much overkill.

T
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« Reply #220 on: September 30, 2009, 05:15:12 PM »

Tom,
No Antenna simulation the past two days. Peter broke his arm in 2 places taking a block as he was about to sack the QB. We thought it was just a strain until we saw the Xrays. He will be ok but out for a while. I will be doing something different if the WX isn't too wet this weekend..
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« Reply #221 on: September 30, 2009, 07:05:32 PM »


Tom,
Are you using good saddles on your U-clamps?  In the past most of my troubles with slipping booms or slipping mast clamps have been attributable to saddles that allow the tubular boom or mast to slip due to lack of 'grip'.  No amount of tightness or number of clamps can make up for bad saddles.
73, Karl


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« Reply #222 on: September 30, 2009, 09:33:11 PM »


Tom,
Are you using good saddles on your U-clamps?  In the past most of my troubles with slipping booms or slipping mast clamps have been attributable to saddles that allow the tubular boom or mast to slip due to lack of 'grip'.  No amount of tightness or number of clamps can make up for bad saddles.
73, Karl


Hi Karl,

You're right about the saddle to form-fit the tubing. I don't use a saddle, but more of a "cradle" with less surface area - I either pin the tube or tighten the u-bolts until the tube starts to flatten slightly. The flattening makes it hard to turn. Heavy wall aluminum doesn't seem to mind it. A saddle would surely help and I will add some if this solution doesn't work out.  

I think the problem I am having is due to the wind swinging the boom. This twist causes other things to move in other directions. By adding the second strut, the beam won't sway horizontaly nor twist longitudinally. I finished the three sidearms tonight and will give them a try tmw. I added a hole to put in a boom pin if needed later. I'll post some pics tmw of the new arms and hopefully the installation - if it's not too windy up there tmw.


Frank - Hope the JN recovers OK. At least it was in the line of duty... Wink

T
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« Reply #223 on: October 01, 2009, 06:54:06 PM »

Well, built the three sidearms last night and installed the bottom one today.  I made a few mistakes and had to climb up and down three times... Embarrassed

Anyway,  after installing the first one I found the Yagi is rock solid now. It is anchored into the tower on all three legs and does not move at all like before.  I think this will do it.  Tmw I'll go for the gusto and do the middle and top Yagis.

Shuda done it this way from the beginning... Wink


In the pics below notice the sidearm that anchors to the two tower legs. It supports the weight -  along with the overhead trussing.  The new sidearm that goes from one leg to the boom helps control side-to-side rotation and boom twist.  The sidearms pictured are made from 4" X 3" angle steel, 3/16" thick.  The big u-bolts are 3.5" using 1/2" threads.  The smaller ones are 2" using 3/8" threads. All stainless, of course.

The 36" sidearm, already installed, was a heavy one to haul up. Tied it to my belt and climbed....

I feel much better already...

T


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« Reply #224 on: October 01, 2009, 09:45:23 PM »

Well at least it wasn't 20 feet long looks much better now.

Tom, Just got 2 elements flat side down 20 foot spaced to work in simulation. All it needed was a 1:2 turns ratio transformer at the feed point. This gives me a nice VSWR across the band. A tad less gain than HUZ around 9.8 dBi and similar FB but it plays across the whole band. Now to figure out how to swap the pattern. I'm thinking a pair of 200 ohm feed lines to a relay. This might also work with your 80 meter loops. Imagine pulling the bottom up flat the increase in average height if it works. I was getting about 175 ohms at the feed point.
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