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One - Do- Tree... Tests with the 2x2x2 40M Yagi stack




 
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Author Topic: One - Do- Tree... Tests with the 2x2x2 40M Yagi stack  (Read 156998 times)
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K1JJ
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« on: September 02, 2009, 10:45:08 AM »

Finally got the third 40M Yagi up and connected up the phasing lines.  I made some notes that I will post here as I progressed through the initial tests yesterday and last night. 

I used a reference dipole at 45' high to compare against the 2x2x2 stack into Europe. I saw some very surprising results, including some early false disappointments.

Lots more tests to be run.

The three Yagi heights are:  190', 125' and 60' high, all fed in-phase for a take off angle of 13 degrees on the horizon, northeast to Europe. Full size elements, each Yagi weighs 250 pounds, reflectors = 70' long, driven els = 65'.   No high angle on model or experienced in operation.


Tom, K1JJ


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« Reply #1 on: September 02, 2009, 10:49:04 AM »

Included are some shots of the 75M two element delta loops at 190'. Look carefully to see the wires hanging off the boom. This has relays that make it switchable to USA, NE or SW using a coaxial stub across an inductor to tune the reflector.  The two 5el Yagis below the delta loops are the homebrewed, stacked 60' boom 20M Yagis.


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« Reply #2 on: September 02, 2009, 10:50:35 AM »

More shots.   Notes to follow about performance tests.


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« Reply #3 on: September 02, 2009, 10:51:22 AM »

Really nice installation Tom!  How are you feeding them in phase?  What kind of combining arrangement are you using?

73,  Jack, W9GT
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K1JJ
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« Reply #4 on: September 02, 2009, 11:10:38 AM »

Here's some notes I made of emails to Steve, HUZ about the tests last night. I've included them here knowing other 40M enthusiasts will find them of interest...  ( I didn’t post Steve’s responses – didn’t axe his permission yet)

------------------

5PM Tuesday evening - 2 hours before sunset:

Steve,

Well, got it hooked up today.

I checked each Yagi using a 1/2 wavelength feedline. The Yagis are designed to be 50 ohms j0 on 7150.   They were all between 55 ohms to 60 ohms,  j10 or so.  Not bad at all.  They should combine nicely.

The resulting swr into the 50 ohm hardline line was about 40 ohms.   The doghouse 75 ohm hardline saw about 65 ohms or so.   So, the overall matches are decent.


At about 5PM, two hours before sunset I compared it against the low dipole at 45'.  To my surprise, the dipole was about 2 S-units louder on all Euro stations, including the BC stns!   I thought for sure something was wrong, like I reversed one of the driven elements feeds.  Later at about 6pm the dipole was still an S unit louder. I was yellafied.  Failure – Loser!

I was baffled cuz the f-b was very good on the USA stns, like 20-25db or more. The side rejection was also good down to S.A. like 30db at times.  But no forward gain.


I took Yaz for a walk and came back at sunset.  Now the two ants were equal. Looks like the angles started real high and were coming down.  I heard a 9K2MU  in Kuwait and he was about  8db louder on the 2x2x2!  The Euros were slowly starting to come up slightly on the stack too.

At about 9PM I came in and tried it again. It was like night and day.   I first heard a G4 who was S9 on the low dipole and 20 over on the stack!  I heard some 9K2's calling CQ and I could barely hear them on the dipole - they were S9 and actually loud on the stack. All the Euros were between 10-20db louder on the stack til about 9:30, present time.   It was now working as it should all along – all because the angles were now coming down rapidly.   


I also notice that the QSB is very fast on the stack. It's like a flashlight that must hit the right angle to really play - if the angle is off, the signal drops off big.  Some of the peaks were tremendous like 25db difference compared to the dipole, but short lived.  This shows the band has lots of variations. One night 13 degrees TO (the stack) will be favored big time and it will really play, I guess.


There appears to be no high angle on this stack at all, as the modeling shows. On some USA W4's they are +45 over on the SW wire Yagi and drop down to a watery sounding S5 on the stack. This is rare, but shows there are some rear lobe "tuck in" going on. 

I think I will need another wire Yagi NE at about 70' to cover the higher angles. This thing's TO is as low as a vertical will have a big gap at times. Can you imagine the low dipole being TWO S units louder than the stack before sunset? This shows they are really totally different antennas to see that much delta over the short band time I checked.   It appears the angles go from maybe 60 degrees down below 20 degrees as the sun sets.  I'll see what happens later tonight.

This is a one job antenna system, caw mawn.


T



Steve,

I'm not sure what happens to the angles in the winter on 40M.   At least the trend appears that nighttime is good for low angles.     I always thought when the D layer disappeared at sunset, the angles would be higher cuz of the higher layer, but not so.  During the day to Trons, the high antennas always were better. At night the lower ones worked best to Maine.

The past high angle VK thing on 40M must be similar to what I saw today.

Anyway, no, not on the air yet. I need to test the whole system for 1500w yet. Even the 75M relays haven't been given a test.  Any of this stuff cud blow out.

I have the 2x2x2 hardwired all in-phase.  I do have a WX0B switchbox and cud switch all the combos, but Chuck tells me that 95% of the time the all in-phase is the best. He had one on his 2x2 stack and later removed it.

We'll see how it plays over the next few days.  But I do need something to cover ~ 25-30 degrees TO like you have.  I don't want to be making excuses all the time like the vertical guys do about their low angles, etc.... :-)


To select only the lowest Yagi, the other Yagis in the stack have an effect on the pattern. It's not clean in the vert plane like using a single Yagi at 70'.  But when all are driven with the middle one 180 out, the pattern is quite nice at 30 degrees or so.  I COULD use a 180 degree coax line wid a relay. I'll do some modeling. It wud eliminate having to put up another wire Yagi maybe.  I’ll have to think about this some more.


T



Steve,

I just heard a guy from W2 say the band was acting "funny" tonight and cornditions were very poor.  The Italian stn he was working was S3 on the dipole and S9 on the stack.   Maybe he means the angles are low tonight and his dipole is high angle, dunno.  On the stack the band seemed hot…


At 10:30 I see the delta between the two is still as big as it was at 9:00PM. Still see 10-20db difference.  Great! I tuned in a bunch of BC stns all the way up to 7300 and see a good 15-20 db diff.  The 2el Yagis can go high in freq cuz the reflector keeps working. If it were a 3el, the dir wud screw it up above 7200 or so.


The stack seems more stable right now and the low dipole is fading badly. So guess the low angle stuff is taking over now.   That's good news for me... :-)


Anyway, all in all, it looks like this 2x2x2 may be one of the best systems I've ever put up. It's so optimized for one purpose it HAS to work when the cornditions are right.

T


Steve,

At 11:10PM:

The angles are dropping even more and the stack is becoming very  stable and loud.

The low dipole has deep fades and is PW.

I'm finding the f-b and side rejection is huge.  These low angles make it so.

I'm gonna hit the sack, but wud be curious to check this some time until morning to see what happens.


What a huge difference in cornditions between now and at 5PM earlier tonight.   I never wuda believed the angles changed that much.

T

--------------------


Steve,


Listening at 1:30AM in the early morning to 40M...

The biggest differences yet.   I hear western Eur with S1- S2 signals on the dipole with S9 on the stack. 

The VK's are almost the same strength on NE or SW Yagis, showing it's probably high angle from them still.

The angles stateside seemed to have risen, as the f-b on the stack is not as high as earlier.

The stack is performing something like the  5X5 on 20M -   big signals and fast fading showing it is very selective and narrow in the vert plane.

 
T


More tests to follow from tonight’s action…
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« Reply #5 on: September 02, 2009, 12:04:58 PM »

Tom,
This sounds like a real cool interface into 3 SDR receivers and do phasing in software.
Or set up switching/phasing to select any combination of 1,2 or 3 antennas
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« Reply #6 on: September 02, 2009, 12:52:22 PM »

I can listen for ya around 11 PM your time (6 AM my time) here in SV, Tommy.   I just have a 30' wire thrown into a tree so xmitting is prolly out of the question. 

What channel ya being on, caw mawn
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« Reply #7 on: September 02, 2009, 01:20:35 PM »

Really nice installation Tom!  How are you feeding them in phase?  What kind of combining arrangement are you using?

73,  Jack, W9GT

Hi Jack,

All hardwired in-phase for now.  I may later try my Stackmatch which permits in phase, out of phase, upper alone, middle alone, lower alone, etc.  Though I like to keep it simple for durability and might make a lower wire Yagi at 70' to cover the higher angles into Eu. The higher angles certainly appear to be important at times.  For combining the Yagis, I just made them all about 50 ohms and tie the three RG-213 coaxes together. This gives 16 ohms. I then go into a 1/12 wavelength coaxial balun to bring it back to 50 ohms. This connects to a 50 ohm hardline run that's down the tower. At the doghouse I use a 50 > 75 ohm torroidal balun to go into the long underground run of 75 ohm hardline to the shack.  In the shack I deal with 75 ohms using a pi-network - no problem.



Frank:  The separate SDR RX would require a separate feedline run to the shack for each Yagi.  I now use about 550' of hardline for the run, so it wud be out of the question. I have other feedlines run, but they are for other antennas, like the bevs.


Johhny:  Glad to hear you're doing FB in Greece!  I don't expect to transmit with the stack for a few days yet.  I want to test a lot of stuff first and it can all be done on receiving. Also want to run a smoke test. Nothing worse than it stuff failing on the air cuz it was rushed.  I'll send ya an email when we get on. I think Huz will be joining us, as he's pretty active and wants to size up the latest competition... Grin

T
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« Reply #8 on: September 02, 2009, 01:47:49 PM »

I have a US phone # here (HUZ has it) and can give you real time feedback OM as to how many pounds yer pushing.  Gimme a call when you're testing, I'm usually up before 6AM SV time.
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« Reply #9 on: September 02, 2009, 02:28:26 PM »

Here's my response.

Drool .... slobber..... drool......duh, .......... nice antennas dude. I'm selling out and taking up stamp collecting!   Grin



Here's some notes I made of emails to Steve, HUZ about the tests last night. I've included them here knowing other 40M enthusiasts will find them of interest...  ( I didn’t post Steve’s responses – didn’t axe his permission yet)


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« Reply #10 on: September 02, 2009, 02:43:35 PM »

Tom Vu,
You could mount 3 softrocks on the tower and convert down to 10 KHz and send audio back to the shack through 6 shielded pairs. And work some software magic.
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« Reply #11 on: September 02, 2009, 04:17:28 PM »

There's a 1-lander doing that with a bunch of verticals. Makes some very sharp patterns with relatively little real estate. And he can steer it in almost any direction.
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K1JJ
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« Reply #12 on: September 02, 2009, 04:54:37 PM »

Interesting on the software steerable verticals, Steve. Which one-lander is doing that - on both 40 and 75m?

Yes, Frank, I wud imagine playing with phasing for just receive cud create a nice edge since angles appear to change so quickly on 40M - and by large amounts.  No wonder many of the guys here have been talking about signals dropping out quickly at times.

Though, this Softrock stuff wud be for receive only.  I wonder how they handle a lightning strike on the tower.... Shocked  I wonder if it's better to do it with simple phasing lines/torroids to include transmitting  side too.


One thing that has been bothering me - did I connect the inner coax lead to the same driven element side on all three Yagis? I remember doing it for two, I think, but the third one might have slipped by, dunno. There were months in-between each one's construction.  The only way to check it now is to put 9V on the coax on the ground and climb the tower with a DC meter. I'd need to reach out with a pair of long aluminum poles connected to the meter to touch both sides of the driven elements to make sure the polarity is the same on all three.   I wud think the performance wud be pretty poor for low angles if one was reversed, according to modeling, but it still haunts me. Gotta get up there and see. [And, if one IS wrong, it means unbolting it and spinning the boom vertical on up the tower to get at the connections - yikes]

T
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« Reply #13 on: September 02, 2009, 06:59:42 PM »

Tom,
I've been looking for the link Huz talked about but can't seem to find it yet. I think he uses 4 receivers. I would put a relay on each input to disconnect the RX when power is off. One of the guys I work with  was flying last week and the plane was hit by lightning.
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« Reply #14 on: September 02, 2009, 09:22:32 PM »

I was listening tonight on 40M.  SAME pattern. 

At 5PM, the low dipole was 2 S-units louder than the stack into Europe. It was like the stack was broken! Then they were about equal at 8PM, after sunset.  Then about 9PM the stack started to improve very quickly until now (9:30 PM) the stack is between 15-20 db louder than the dipole when listening to Germany. The dipole is very PW at times.

The big improvement happened very suddenly after 9PM, within a few minutes. Same pattern for the BC stations.

I'm still on the fence of whether to switch the stack or put up a new wire Yagi for the higher angles. I just might convert the low dipole into a higher angle wire Yagi for Europe.  Switching the stack with relays is somewhat undependable at best.


The modeling of the two antennas shows why there is such a big difference. It's much to do with the lack of high angle lobes on the stack - and the lack of low angle lobes on the low dipole.  The difference at 30 degrees T.O angle between them is easily 20-25db.

(Heard the HuzMan holding court on 7138.)


T
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« Reply #15 on: September 02, 2009, 09:27:46 PM »

Aren't new antennas fun?  Grin

And do I know that sinking feeling at first when something doesn't seem right.  

>We'll see how it plays over the next few days.  But I do need something to cover ~ 25-30 degrees TO like you have.  I don't >want to be making excuses all the time like the vertical guys do about their low angles, etc.... :-)

I had some fun last night reading the mail on 75 with the vertical and the high band dipole both fed into the out-of-phase phase nulling box for a sort of diversity reception thing (I was too lazy to go hook up the low band dipole).  

Yes, 40 will change dramatically in a minute.  I've been in early evening cloud burner QSOs and poof everyone's gone like a switch got thrown.  In winter it'll happen around 5 or 6 p.m. local.


Rob
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« Reply #16 on: September 02, 2009, 09:44:41 PM »

http://k1lt.com/

Here you go
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Steve - WB3HUZ
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« Reply #17 on: September 02, 2009, 09:47:16 PM »

Yep. That's the guy. I was just going to post it. Seems like it could be the ultimate receiving set up.


The softrocks are in the shack IIRC.
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« Reply #18 on: September 02, 2009, 09:52:58 PM »

So does huz have the same problem with his loops?
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Steve - WB3HUZ
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« Reply #19 on: September 02, 2009, 10:03:42 PM »

Which problem is that?
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K1JJ
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« Reply #20 on: September 02, 2009, 10:11:02 PM »

Interesting approach this guy has for receiving antennas. After reading it over, my feeling is it uses too much hardware to accomplish directivity. I'd much rather do what W8JI does and that is use multiple terminated beverages in a circle and select the proper one with relays - that's it.

The patterns on some of the "steered " directions are not that clean, though usable with the 8 verticals.  I think a pair of phased beverages looks much better in the favored direction.

It does take up some room on 160M for spacing the verts apart.

It wud be a cool technology project to play with, but I'll stick wid simple beverages here.


BTW, I made up my mind to switch the 2x2x2 stack for higher angles. The modeling shows that by simply feeding the lower alone OR the lower and middle OR all three gives a nice, gradual selection of vertical angles - clean too. I'll make up a heavy duty relay box that keeps the bottom one on all the time and clicks in the middle and top Yagis one at a time. The swr will be as much as 2:1 with the lower Yagi alone, but I can live wid that.

I might even use my StackMatch, but doubt that can handle the abuse of AM operation...  Grin


As Franked axed, Steve, have you compared your loops against some other reference antenna and see a big difference in angles at 5PM vs: 10PM?   Maybe your loops are pretty much in the middle of the vert range and don't move around much, I dunno.
Frank, there's no problem, just that the angles need to be low for the stack to do its job, if that's what you mean.

T
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And, nothing like an old dog.
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« Reply #21 on: September 02, 2009, 10:13:03 PM »

drastic changes in performance as the time changes after dark
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« Reply #22 on: September 02, 2009, 10:21:03 PM »

Tom give some thought to impedance transformation switching so you end up 1:1 in all three positions. Or am I getting sleepy. Been playing with my Daughter's new computer all night.
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Steve - WB3HUZ
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« Reply #23 on: September 02, 2009, 10:24:00 PM »

No. I haven't noticed anything like Tom has. I wouldn't expect to either. His antenna has a take-off angle that is much lower and the vertical lobe is much more narrow (compressed) too. His antenna is more like a laser beam. Mine is like a flash light with pissweak batteries.

I can work Europe easily well before dark - several hours on most days. A few weeks ago I worked several German stations at 5PM local. Both were over S9. I had two EU stations come in at 15-20 over 9 at 7PM ET tonight. Also worked a VK6 on the long path. There is usually a good peak in signals from EU about an hour before local sunset and again close to EU sunrise. But good signals can be heard throughout the night. I'm guessing 40 might be open to EU almost around the clock in the winter.
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« Reply #24 on: September 02, 2009, 11:04:45 PM »

Tom, that high angle killed us in DX contests until I put the 2nd 4 el 40 down at 50' and used lower/upper/both switching. We discussed that at Nearfest.

The same thing happens on 160/80 also.

Now what you really need to do is put one amp on each antenna and have a voting system for receive Grin Or the phased Beverages.

Carl
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