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

[Steve - WB3HUZ]

Awesome. So ultimately, you'll have them at 65 feet?

[WA1GFZ]

Within a foot or so. Tom thinks I should put a guy wire above it supporting the ends. This will take up a foot or two above the boom. I'm using 2 inch thick wall 6061 T6 tubing 20 feet long and have some nice commecical grade clamps 1/4 inch thick steel. Last weekend bought all the SS hardware so just need to find a hunk of guy cable. I think I have a little left from the last toweer rebuild. I hope to build the boom Saturday AM. I hope to get it in the air sometime this weekend between the 9 other things that need doing. The boom will point 30 degrees north of East bolted to one face. Looks like the trees in the yard line up so ends will be around 50 feet.

[Steve - WB3HUZ]

Have you considered using one of those vaulting poles?

[K1JJ]

TIGHT !! 


Frank,

2" is not really that big of a diameter. Without trussing, it will probably sag 1-2' once you pull down on and tighten up the inv vees anyway.  Plus you have coax coming from each dipole to the tower with a balun and ferrite sleeves at the feedpoints. Plus ice... yikes.

When the next ice storm comes, you will be happy you have overhead trussing. Also, remember what I said about the mechanical advantage produced by overhead trussing vs: just bolted to the tower at the middle of the boom.  Picture a hurricane and the boom is bolted to the tower in the middle. Then add guy cables to each end pulled up and attached on the tower. Which one has more up and down rocking control and puts less force on the tower?
The extra 1-2' lost in height will not be seen on any S-meter. In fact, it will help your dipoles become flatter.  50' on the ends makes a good dipole apex angle. Shud work really FB.


BTW, a 40 degree heading is just fine. It will better favor the Russians in Moscow, Asiatic Russia, etc. Also India is farther north, about 30 degrees.  I have my Yagi stack beaming about 40 degrees too and am happy with the coverage. I even find the Swedish and Finns to be within the main lobe.  However, the Moroccan stations (N. Africa) at 75 degrees are way down, about equal to the low dipole.

T

[WA1GFZ]

Yea, I know but it is only 10 feet radius. I'll have room for the cable since the log is only about 2 feet above the top of the tower. I'll check home cheapo if I need some cable but I think there is some in the basement.
Pole is a good idea and we can dream about working the vaulter
 

[WD8BIL]

She don't look Polish

[WA1GFZ]

Tom, the pipe is at least 1/8 inch. Anyway I found a bunch of guy cable 3/16 & 1/4
inch. Plenty of clamps some dead ends. I thought I had some of those thinble things to protect the ends but have not located any yet. I guess I could use SS tubing and bend it. Brake line might work. I only need 3 or 4 of them so I'll work something out. no fun being PW but nice to see the RX S meter change when the pattern is flipped. I'm running out of excuses.
HUZ you really strap.

[Steve - WB3HUZ]

When you get that thing to full height, I'm gonna be in trouble.  {Come on trees, grow faster!}

[KB2WIG]

This  pole design is cut a little fuller.

[WA1GFZ]

store a little energy in that pole

[K1JJ]

Looking for suggestions....

I'm finally getting around to switching the 40M Yagis.   But I'm confused what to make of the impedances when I switch the top Yagi  (of three)  180 out.  180 out of phase on the top Yagi gives a single lobe at 30 degrees.

However, the impedances almost halve on the top two. So, the swr will be high on them and cause an unwanted phase shift, no?


Here's the impedances when all in phase according to modeling - in the real world I see about the same on the MFJ-259B:

44.4 + j5.7  bottom
56 + j1.6  middle
40.8 +j6.9  top
OK-fine



But modeling shows when the top is 180 degrees out:

50.5 +j4  bott
33 + j10.6  mid
24 +j 14.9 top

Since I can't match these at the feedpoint for each Yagi on the fly, I am stuck with this swr on the upper two when 180 out.   Should I just feed them as-is with the extra 180 degree coax attached to the top Yagi or will I have intolerable phase shift that will cause pattern problems?

I could add or subtract coax to each Yagi to compensate, but that wud make the switching way to complex. I already need 7 relays to do the complete job.



I'm also having my second thoughts about the value of the lower two in phase alone - and the lower one alone.  They seem to overlap in pattern a lot with the other two patterns. (Four patterns total)  It seems all in phase   or the top one 180 out makes the best and simplest pair of patterns.... 13 degrees and 30 degrees.  But the 180 out as described above has potential matching problems.  The stack works so well as-is all in phase, I'm tempted to leave it alone and let the low angles do the work most of the time.  It's no small job to build up the switching relays and phasing lines and climb up there to install and test.  Just like combing a $2,000 hairpiece.

Any ideas?

T

[Steve - WB3HUZ]

Looks like you'll be making some L-networks.

[WA1GFZ]

Might be easier to build a high angle antenna for NE. You don't want a bunch of switching up on the tower. I would bring all the switching to to the ground if you want to play science project.
I'd tend to leave it as is. Since it works so well.

[K1JJ]

Might be easier to build a high angle antenna for NE. You don't want a bunch of switching up on the tower. I would bring all the switching to to the ground if you want to play science project.
I'd tend to leave it as is. Since it works so well.

Frank,
Yep, I modeled a high angle system and it looked FB for a long boomed Yagi or collinear elements at 65'..   Though it adds more interaction to the antenna field.  I'll bet in the end, the stack is still the best performer, even at higher angles like 20-25 degrees. Above that, then the ionosphere is disturbed.


Steve,

I can just imagine switching in and out additional L networks. I'll be up to 12 relays in no time...

Even though I bought the relays and cut the phasing lines already, maybe I'll try modeling an ass kicking NE wire array at 65' to fill things in.  How about 2-half waves in phase with end-to-end reflectors and a bunch of directors?  Or a 7 el delta loop?  Problem is, the only open area is to the side of the stack and modeling shows the stack interacts poorly with stuff to the sides.

When you three guys come over for HossTraders, maybe I'll put the Huzman Delta Loop Company to work...

T

[WA1GFZ]

Why not just run the bottom or center beam alone for high angle and screw all the phasing stuff. Then you don't have to add any more antennas. You didn't get into trouble until you messed with phasing. How about duplicating the first configuration that was high angle and matched. I think you are trying to get too fancy making life complicated.  I still think your best bet it to bring the feed lines to the ground and play there.

[w3jn]

LOL

Heard on 40 just now from a 4X4 - "What are you doing there, is it MAGIC?"

[Steve - WB3HUZ]

Yea, that was funny. 4X4BL was incredulous. He couldn't believe Tom's signal.

[K1JJ]

Yea, that was funny. 4X4BL was incredulous. He couldn't believe Tom's signal.

So you were listening in from Greece, Johnny?  Does it feel like you could make the TX path back based on some of the stations we worked - using your short wire?

Yes, last night was the BEST low angle night on 40M to date. I had one middle east station see about 30db between the reference dipole at 45' and the stack later on. I was on until about 1:30AM... four hours last night.  It appears that the 13 degree take off angle is gonna be perfect for all around use. I was really worried that it wud be too low for Western Europe, but with the performance for long haul, it's a good compromise.


I was amazed last night with Huz's hearing ability. He added a second beverage the other day (two phased) and could hear about anything thrown at him.  I just KNOW there had to be people scratching their heads down in 4-land about what he had running there...

That was a great time last night with lots of laughs.  Hope you join us, Frank, after raising that new boom today and getting your new array fired up.

[K1JJ]

Why not just run the bottom or center beam alone for high angle and screw all the phasing stuff. Then you don't have to add any more antennas. You didn't get into trouble until you messed with phasing. How about duplicating the first configuration that was high angle and matched. I think you are trying to get too fancy making life complicated.  I still think your best bet it to bring the feed lines to the ground and play there.

Frank,

Unless I run ALL three Yagis in SOME kind of high angle config, the reduced gain results in a lobe that is not much different than the all-in-phase config. ie, At 25 degrees, the lower Yagi is about 11dbi. The in-phase stack is also about 11dbi at 25 degrees. (Down from 15dbi at 13 degrees)

So the only config that makes sense is the 180 degrees out, using all three Yagis for a single lobe at 30 degrees.  But there are matching and phase issues.

To bring the feedlines down to the ground would add additional losses and expense for more feedline. If it doesn't work out I'm stuck. So I may just leave it all alone and have a more reliable system with no switching at all - all hardwired using no connectors - bulletproof.  The low angle in-phase config seems to work well 95% of the time - and may turn out to be best 100% of the time if the experiment fails...  Maybe next year I'll get antsy.

The bottom line is I never expected the optimum angles to be so low into mid-Europe and Russia/ Middle east, but they appear to be so at this time.

T

[N3DRB The Derb]

 I have come to the conclusion following all of this for weeks that HUZ and JJ are having too much fun. 

I am attempting to get my antenna back up in the air. if I can stumble around a bit more today without crapping out.

[Steve - WB3HUZ]

The band went really long. I couldn't hear you after a while. There were some Russian stations calling but I don't think you heard them since they just kept calling.

I moved up to 80 meters for a while. The place was hopping. Lots of nice signals from EU-land. I bagged it at around 2:30 AM. EU stuff was still coming through even though they were in daylight.

Yea, that was funny. 4X4BL was incredulous. He couldn't believe Tom's signal.

So you were listening in from Greece, Johnny?  Does it feel like you could make the TX path back based on some of the stations we worked - using your short wire?

Yes, last night was the BEST low angle night on 40M to date. I had one middle east station see about 30db between the reference dipole at 45' and the stack later on. I was on until about 1:30AM... four hours last night.  It appears that the 13 degree take off angle is gonna be perfect for all around use. I was really worried that it wud be too low for Western Europe, but with the performance for long haul, it's a good compromise.


I was amazed last night with Huz's hearing ability. He added a second beverage the other day (two phased) and could hear about anything thrown at him.  I just KNOW there had to be people scratching their heads down in 4-land about what he had running there...

That was a great time last night with lots of laughs.  Hope you join us, Frank, after raising that new boom today and getting your new array fired up.

[w3jn]

Yep, I was listening.  I trimmed the wire a bit so now I get +/- full power out of the TS-50.  I'll listen and give you a call when I hear ya again.

I'm in pretty tough shape here.  All I have for radio stuff is the TS-50, the power supply, a 10' length of RG-59 scarfed outta the trash at work, some wire, and a few clipleads.  My sea freight's on a truck somewhere between here and Holland, which should have an ample supply of radio goodeez, including the FT-1000, a 1KW solid state leenyar, a Junkston 1KW flashbox, the Agilent service monitor, a network analyzer, parts, pieces, etc . 

My little Caddy is sitting in a container in Pireaus, awaiting customs clearance.  Taking the frigging bus is getting REALLY old, 'specially going food shopping.  'Sides, first on the agenda is take a pic of me in front of the Cadillac wearing my bigassed furry Uncle Sam hat that HUZ so generously gave me as a going away present 

[K1JJ]

The band went really long. I couldn't hear you after a while. There were some Russian stations calling but I don't think you heard them since they just kept calling.

I moved up to 80 meters for a while. The place was hopping. Lots of nice signals from EU-land. I bagged it at around 2:30 AM. EU stuff was still coming through even though they were in daylight.

You were hearing exceptionally well on 40M last night.

Last night those mid-European stations kept calling us and many times covered up the Russians for me - even when we repeat over and over "Russians and mideast only." I don't know if they just don't understand or they want to slip through the net...     I don't have the heart to tell them to shut up while we work the weak ones, but maybe next time.  They seem to eventually catch on when they get no response.  Heck, western Europe can work us any time, but when the band is long, it's a rare opportunity for the weak ones to get through.

Yeah, after I left 40M I listened to 75 and heard some UK stations holding court. I think I'll try 75M tonight. Haven't even tested out the new 75M delta loops yet, so might as well.  We'll let Frank have 40M all to himself.  If 75M is dead, we'll try 40M again for some action.


Johnny,  yes give a a call. We'll make a special effort to pause for you at times, in your caddy and fat cat US hat.

T

[Steve - WB3HUZ]

It got so bad an HB9 station used a fake RU3 call just so you would come back to him! Everyone wanted to work Tom Vu! It must be magic.
 

Last night those mid-European stations kept calling us and many times covered up the Russians for me - even when we repeat over and over "Russians and mideast only." I don't know if they just don't understand or they want to slip through the net...     I don't have the heart to tell them to shut up while we work the weak ones, but maybe next time.  They seem to eventually catch on when they get no response.  Heck, western Europe can work us any time, but when the band is long, it's a rare opportunity for the weak ones to get through.

[Steve - WB3HUZ]

Looks like the 75 meter array is working FB too. 

M1WDK           3793.0 K1JJ         5.9 plus 50 db tom cq cq EU        0129 20 Sep