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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 165248 times)
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K1JJ
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"Let's go kayaking, Tommy!" - Yaz


« Reply #25 on: September 03, 2009, 09:40:38 AM »

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.

Frank,

How would you go about doing this with the minimum hardware?  Relays and coax or relays and torroidal transformers?


1) It would be nice to do lower alone, lower and middle in phase - and all three in phase. (3 selections)


2) OR keep them all in phase and just put the lower out of phase with the rest - and the upper out of phase with the rest. (2 selections)

At this point it's hard to say which ones are most useful. Putting the bottom out of phase with the rest results in a strong 60 degree TO angle.  Making the top out gives a strong 30 degree angle. That's with all three working. If I do just the lower, etc, the gain is reduced.  All three in phase give a 13 degree T.O., very low.
 

I have a WX0B Stackmatch I plan to try, but it is fragile and does not have 180 out in it unless I buy an expensive add-on.  These boxes cost too much for what is in them.

T
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« Reply #26 on: September 03, 2009, 09:51:10 AM »

let me think about it after a good night's sleep. I'll day dream while writing this stupid procedure I need to finish today.
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« Reply #27 on: September 03, 2009, 10:34:07 AM »

Tom, if you have access to the NCJ or Scuttlebutt that should be covered in detail many times over the years.

Id suggest just relays as they are a miniscule part of the phasing path at that frequency. Coax will have no measurable effect on phasing or bandwidth if cut right. 

Do the combinations as elaborate as possible at first until you get a feel for what works best and then simplify.

Carl
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« Reply #28 on: September 03, 2009, 11:14:02 AM »

I just sent you a schematic with 3 relays to select 1, 2 or 3 antennas.
You will need a 1:2 splitter for 2 antenna operation. I assume bottom antenna for 1 , two top antennas for 2 and then all 3
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K1JJ
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« Reply #29 on: September 03, 2009, 06:10:18 PM »

Tnx for the drawing, Frank. I'll have to think out what I need to do.


Yep, I screwed up. As a phasing test, I put 9 volts on the coax and climbed the tower to see if the element halves have + voltage on the same side. (all in phase)  I figured it was a waste of time, but wanted to be absolutely sure. Wouldn't you know it - I spaced out and the middle Yagi had the inner conductor connected to the opposite side as the other two. The middle is 180 degrees out of phase compared to the others! Yikes.  The pattern models out to look rather poor. I cannot understand how it works so well for low angle.  It has a HUGE lobe at 60 degrees and a small one at 13 degrees.

Anyway, to fix it I can either spin the boom vertically on the tower and swap the leads - a rather risky operation for one guy - or, I can remove 45' of coax (1/2 wavelength) from the coiled hank going to the middle Yagi to get it back in phase wid the others.

Either way, the matches will change and I'll need to spend time dicking with that again up on the tower.  The other day I wondered why I had a different match reading than the model showed when I put the three feedlines together. When measured individually, they were about 55 ohms, but when put together, the out of phase Yagi has a huge effect on the others. Now I know why.


So, back to square one wid the testing tmw... cheez.  The bright side is that hopefully the system will work even better for the low angle stuff. Probably less fading than what I saw before cuz the lowest lobe will be MUCH fatter since the lobe at 60 degrees will be gone and pushed down into the 13 degree lobe - once they're all in phase..

T
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« Reply #30 on: September 03, 2009, 07:18:49 PM »

Fun and games Tom eh, you certainly have my sympathy; this kind of thing makes you want to cry, it does me at least.  On a much smaller scale I about killed myself getting one of the masts up and had a pulley bind up on me raising the big dipole feedpoint; I had a second one up there with a rope through it (thank heavens) so I abandoned the binding one and put the feedpoint and one of the short dipole ends on one pulley.

But back to ur yagis--I wonder if the fast QSB you observed was due to phase cancellation from the same sig arriving at high and low angles and battling with itself.  Sort of like what you get on FM bc band when an airplane flies overhead.

Rob
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« Reply #31 on: September 03, 2009, 08:07:40 PM »

Tom,
I always mark the hot side of the coax on any antenna I build. Try putting some tape on the hot side element so you can see it from the ground.
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K1JJ
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« Reply #32 on: September 03, 2009, 09:18:34 PM »

Tom,
I always mark the hot side of the coax on any antenna I build. Try putting some tape on the hot side element so you can see it from the ground.


Yep, I shud have taken some precautions. I just figured I'd make all the north elements the hot side as I usually do.  It's just that I wasn't paying close attention on the second Yagi and it got by.  I had a 50-50 chance of getting it right, but gambled and lost... :-)  Tmw I'm determined to go up there and spin the boom and fix it.

Rob,
That's a good idea to have two pulleys set up when there are critical situations where you don't want to take it down. You lucked out having that extra feedpoint pulley... :-)

I think fading is two-fold in this situation. Yes, the cancelation of two arriving signal paths is one reason to fade. Another may be when there is a very narrow and compressed vertical lobe (like the stack) and the ionosphere keeps changing. It favors the low angle at times, then changes so that the low angle is not favored. It's like a boiling mass of mirror glass that randomly changes, but still has a major trend as the night progresses.  That's why a stack is used to fatten up the antenna's lowest lobe as it robs energy from the higher lobes. If you're gonna play the low lobe game, might as well have it all down there and make if as broad as possible to accomodate the changing low angles. Use another antenna for the higher angle stuff or switch the stack around.

T
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« Reply #33 on: September 03, 2009, 10:16:46 PM »

Let's hope when you get the middle one flipped the fast QSB goes away along with the 60 degree signals and it's all nice smooth loooooooow stuff.
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K1JJ
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« Reply #34 on: September 04, 2009, 03:45:00 PM »

Spent 4 HOT hours up on the tower today and spun the boom vertically and reversed the coax connections on the middle Yagi. What a job at 125' high manhandling a 250 pounder!  Now they're all in-phase for sure.  The match is now much better - about 58 ohms +j0 at 7150 after the combiner.   I came in at 2:30PM  and listened to the band. I can now hear many Arabian BC stations above 7200. On the dipole they are barely copy-able at times. Maybe a 10-20db difference.  Before the fix, never heard any difference compared to the dipole in the day.

Before the coax fix I was listening to a 60 degree TO angle  with some 13 degree mixed in - no wonder the signals were PW before sunset.

Anyway, the band sounds much busier into Europe during the afternoon and the f-b on the stack to USA is as much as 25-30db++ on certain W4's.  Think it's working FB now - just gotta make up that 4-position splitter/combiner to select the higher angles.


It was worth fixing the Yagi right - now they all have the same coax lengths  - dead accurate and sure for future add-ons.


** Update at 4 PM:  I'm hearing EA4's from Spain coming thru. They are the same strength on the low dipole as the stack.  Looks like closer in western Europe  is still higher angle propagation maybe until local sunset..  The Arabian stations are still 10-20db louder on the stack, showing low angles from them.

T
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N3DRB The Derb
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« Reply #35 on: September 04, 2009, 03:54:41 PM »

as long as you can hear the black james bond, everything will be ok, Tom.  Roll Eyes

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« Reply #36 on: September 04, 2009, 05:17:07 PM »

You will be off the side Derb and PW so you better  QRO OM.
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K1JJ
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« Reply #37 on: September 04, 2009, 05:29:19 PM »

Update 5:30PM:

I hear an ON4 from Belgium.  He is about 2 S-Units louder on the STACK compared to the low dipole.  This is much earlier for western Europe to be louder on the stack - compared to before.

Maybe the late sfternoon/early evening angles were low all along. Just that the stack was broken.  I'll listen again in a coupla hours.

Hopefully the low 13 degree angle is useful much of the time into Eu - we'll see.


** Update 5:40PM:   Taking an average of six Euro stations, they are all about 12+ db or more louder on the stack. It's a good 1 1/2 hours before sunset. This is a good sign!

I'm hearing lots of noise coming from the Northeast, like a storm in the Atlantic. It's at least 15db noisier NE than SW tonight.

Certain USA stations (W4's esp) are NOT copy-able off the back of the stack, while  S9+15 on the SW Yagi.  As the model predicted, the f-b has improved further. Stacked 2el Yagis exhibit a certain "curtain" effect which improves f-b markedly compared to a single 2el beam.

T
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K1JJ
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« Reply #38 on: September 04, 2009, 08:27:16 PM »

8:15 Update:

The sun has set 30 minutes ago and many Euros coming in. The noise is still louder to the NE by about 15db. Probably thunderstorms in the Atlantic.

I've heard the biggest difference to date tonight.  I am getting 20db advantage on the stack easily over the low dipole. It's not a fair comparison, but it IS a comparison since the beginning of testing.   The stack is VERY stable in comparison to the fading dipole. I think that single low, fat lobe is starting to pay off.

I heard an SV1 in Greece calling CQ. I dropped my power down to 10 watts and gave him a call on the stack. He came right back and gave a "59"... :-)  First contact.

The receive difference over the low dipole is so striking now, I am satisfied the stack is working FB. It's time to fire up the amplifier and try holding court over the next few days.

The next project is to add the splitter and relays on the tower at 125' to select the lower, lower & middle, or all three.  This will progressively lower the angle from beginning at 30 degrees down to 13 degrees. 


Does anyone know of a source for those open frame 24vdc  relays that are about 2" X 2" X2"?  I think they were used in furnaces. They make good RF relays - I need about five or so.

T

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« Reply #39 on: September 07, 2009, 10:00:18 PM »

I like P&B DPDT 25 amp contacts used in machines.
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Steve - WB3HUZ
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« Reply #40 on: September 08, 2009, 12:19:30 AM »

JJ was WHIRL WIDE on 40 meters tonight. He kicked my a$$, not surprisingly. He was heard in Indonesia and easily worked Iraq when no other NA stations could hear the YI1RZ.

That stack is killer!
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K1JJ
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« Reply #41 on: September 08, 2009, 09:55:40 AM »

Yeah, Steve, what a blast we had last night! Even the Tron/HLR joined in with us for a while working the Euros.  The pileup was thick and deep for most of the night.

Nothing like trying out a new antenna for the first time.

We worked quite a few old friends and some rare ones. Im still floored to have worked Iraq for the first time, ever. He was running 100w into a vertical with radials over sand. Said he was always losing power cuz of the 2 hour interruptions rolling blackouts.  I could not hear him on the dipole at all, but he was clear and S9+20 on the stack.  A long trip like that is when the low angle really pays off. I held him on freq for 20 minutes looking for North Americans to work him, but cornditions did not permit it.. It would normally have been a riot if he was stronger.

Heres a list of the stations we worked. Many we spent time chatting with. HUZ you were kicking ass wid those delta loops and bevs, caw mawn.


Worked:
G0SGX
GI4PDX
SH8IP
DL2VF
UT5DA
HB9EOU
ER4DX
EC8AIQ
Ei6S
EN8ARG
9K2CQ (Kuwait)
PI4AMF
PR7AE (Brazil)
CN8ZG
G4ZCG
RA3HCL (Russia)
IT9VPT
RN6FJ
SM0XBI
CN8WL
GW6LHF
M3YWH
403A
HB9JC
G6ZBC
LA1WHG
RW3GJ
YI1RZ (Iraq)
RZ6UY
M3TGC
UT4CDO
RA3PET
LZ1QI
RA3PET
SQ7HTK
EC8OJ
DA1AF
Spotted by YC1 in Indonesia on DX cluster
UA1JS (Hiram)

What a great time!

Tom, K1JJ


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« Reply #42 on: September 08, 2009, 11:05:51 AM »

The low angles really seemed to dominate. You always seemed to hear the DX stations much better than I could. When stations were a solid 5/9 at my place, you were hearing them 15-20 dB over 9.

Amazing.
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« Reply #43 on: September 08, 2009, 11:49:26 AM »

I'm sure tom is hearing very well but he does have a unique way of calibrating his S-meter.  Grin
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« Reply #44 on: September 08, 2009, 11:57:43 AM »

old habits die hard Jay.
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K1JJ
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« Reply #45 on: September 08, 2009, 12:24:24 PM »

I'm sure tom is hearing very well but he does have a unique way of calibrating his S-meter.  Grin

Yes, of course, glasshoppa...   Let me give us a "seat of the pants" S-meter calibration lesson...  Wink

To calibrate my S-meter, I pick a night when cornditions are excellent and the 40M BC stations are just crashing in. I then pick the strongest one I can find, like Radio Moscow, etc.  I then calibrate my S-meter so that the station is JUST pinning the meter at +60 over.   Might as well use a reference that is real whirl and uses the full range of the S-meter.

Anyway, when a ham station from Europe is 40 over that means they are within 20 db of the strongest megawatt/curtain array  BC station I can find, etc. Last night one or two DX ham stations hit 45-50 over. That's really doing something for an amateur station!  (ER4DX in Russia and EI6S in Ireland did)  The 50uv= S9 standard, or whatever it is, means nothing to me.   If I run across a newer station that pins the meter past 60 over, I will back down the meter again.

This also makes the DX stations feel good to get big reports. Since it's all relative anyway, they can listen to what others get and know where they stand, no matter how the meter is calibrated.

In contrast, I've heard guys with so called "Scotch" S-meters giving out the strongest stations S7, S8, etc. In this day and age of instant gratification and bling, the DX wonders what is wrong with the receiver or their own signal.

That's my take on it in a nutshell.

The bottom line  is how well can you hear the DX?  No one can hide using extreme QRO, the latest ricebox, etc if they can't hear - no matter what S-meter report they give out. That evens out the playing field and makes it fair, in a way... Grin

T



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There's nothing like an old dog.
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« Reply #46 on: September 08, 2009, 12:38:15 PM »

Didn't you say I was 60-over on your meter one time?  Just call me VOA. I would have said BBC but one of the EU stations used that description for your signal last night.
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K1JJ
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« Reply #47 on: September 08, 2009, 12:51:57 PM »

Didn't you say I was 60-over on your meter one time?  Just call me VOA. I would have said BBC but one of the EU stations used that description for your signal last night.


Yes, definately. You are constantly pushing 50-60 over here on 40M when the high angle cornditions peak. Last night you hit 50 over but later dropped down to S8 as the low angle took over.

What I don't understand is when I listen to other W4's from your area, they are usually nowhere near that loud here or in Europe. I think you have those delta loops at the perfect height for both New England and Europe, depending on cornditions.  If you ever put up that tower and Yagi, I wud keep that system as a reference and fill-in.

Frank is talking about putting up a similar one too. Were you gonna publish the details here at one time?

T
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There's nothing like an old dog.
Steve - WB3HUZ
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« Reply #48 on: September 08, 2009, 01:04:47 PM »

It's my secret weapon. I cannot let it out in the wild.    Cheesy

It's pretty simple really. Just make two full-wave loops and space them 20 feet apart. Feed one and place a shorted coax stub on the other. Cut the stub for best F/B. Make it switchable with some relays. I'll post details this evening.
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« Reply #49 on: September 08, 2009, 01:06:19 PM »

You may a been 60 over, but Tommy told me he used me to reset his S-meter as "the standard".  Remember, when I get on 40 the QRM clears out  Grin

I'll listen for youse gangstas this AM (about 11 PM ur time).
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