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Author Topic: One - Do- Tree... Tests with the 2x2x2 40M Yagi stack  (Read 202708 times)
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K1JJ
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"Let's go kayaking, Tommy!" - Yaz


« Reply #225 on: October 01, 2009, 10:35:38 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.

Yep, two loops on a 20' boom is FB.  As I posted earlier, do the "extended base" on both loops for higher avg height and switch the stubs with a relay. It's a proven system and simple.

What kind of feedline do you plan for 200 ohms?

Just got off 75M DX window. (10:30PM)  The static crashes were 35-40db over. Called CQ and worked about 7 Euros - but decided I couldn't take any more ear abuse and went QRT.... Grin

T
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« Reply #226 on: October 01, 2009, 10:49:32 PM »

Tom,
just got it. two loops about 12 feet tall with 28 feet of 200 ohm feed line. Switch between drive and a short to reverse the pattern. Drive a 1:2 turns ratio transformer. This would put the relay box about 20 feet up the tower.  Feeder could be 200 ohm open wire line. 50 ohm cable to the box with a QRO 1:2 transmission line transformer. I think I will start with a single direction to see how it plays. Under 2:1 across the band
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« Reply #227 on: October 02, 2009, 08:45:59 AM »

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

That should do it Tom!  Heavy duty rules!

73,  Jack, W9GT
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K1JJ
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« Reply #228 on: October 02, 2009, 10:48:16 AM »

Tom,
just got it. two loops about 12 feet tall with 28 feet of 200 ohm feed line. Switch between drive and a short to reverse the pattern. Drive a 1:2 turns ratio transformer. This would put the relay box about 20 feet up the tower.  Feeder could be 200 ohm open wire line. 50 ohm cable to the box with a QRO 1:2 transmission line transformer. I think I will start with a single direction to see how it plays. Under 2:1 across the band

Yep, now you're talking.  

200 ohm openwire will be spaced pretty closely, but shud work FB.    

Sounds like a cross between a broad banded folded dipole and a loop.   You shud get 20db+ f-b no problem.

T
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« Reply #229 on: October 02, 2009, 01:13:26 PM »

Agree but simulation does not show that kind of FB performance at any angle of radiation unless I go to 3 elements. 200 ohm stubs and feeders should be low loss.
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K1JJ
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« Reply #230 on: October 02, 2009, 01:40:11 PM »

Agree but simulation does not show that kind of FB performance at any angle of radiation unless I go to 3 elements. 200 ohm stubs and feeders should be low loss.


Using 2 el deltas on 40M, Huz is seeing 20db++ into Eu and my 2el deltas are seeing 20-30db f-b on 75M.   A 2el delta loop is roughly equiv to a 3el dipole Yagi in f-b and gain.
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« Reply #231 on: October 02, 2009, 01:53:24 PM »

Agree but simulation does not show that kind of FB performance at any angle of radiation unless I go to 3 elements. 200 ohm stubs and feeders should be low loss.


Using 2 el deltas on 40M, Huz is seeing 20db++ into Eu and my 2el deltas are seeing 20-30db f-b on 75M.   A 2el delta loop is roughly equiv to a 3el dipole Yagi in f-b and gain.

That makes sense.  Seems like I recall that the rule of thumb regarding quads vs yagis used to be that a 2 element quad was roughly the same in performance as a 3 element yagi.

73,  Jack, W9GT
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Steve - WB3HUZ
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« Reply #232 on: October 02, 2009, 02:00:42 PM »

The loops can equal the front-to-back (F/B)ratio of a three element Yagi, but will have a db or two less forward gain.

The modeling on my loops shows a little better than 30 dB F/B at 30 degrees elevation.


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ka3zlr
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« Reply #233 on: October 02, 2009, 02:26:29 PM »

What's the Spacing between the driven an reflective elements.

73
Jack.
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« Reply #234 on: October 02, 2009, 03:38:13 PM »

Huz, I think you have a better FB because flat side is up so higher overall height. My simulation shows best FB at around 45 degrees. I'm a little concerned that stuffing 3 loops on a 20 foot boom may end up a bit weird.
Two elements with a 10 to 15 foot tall loop fed at 200 ohms may be a better way to go. Need to work on the FB simulation to see if I can dial it in. VSWR is great and that is when I hit the sack last night.
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K1JJ
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« Reply #235 on: October 02, 2009, 04:20:45 PM »

The loops can equal the front-to-back (F/B)ratio of a three element Yagi, but will have a db or two less forward gain.

You see that much difference in modeling?

I usually saw about 11.5-12 dbi gain for a 3el Yagi 1/2 wavelength above ground  -  and about the same for a 2el delta loop with its avg height = 1/2 wave above ground. (Same boom length)   I wonder why you are seeing 1-2db less?

Maybe Frank, you aren't seeing the high f-b you wish cuz the average height of the loops is < 1/2 wavelength high. As we all know, the pattern tends to get lazy looking when < 1/2 wave high and the f-b goes to hell.


Just got down from a 190' climb. Got the other two sidearms installed. The Yagis are the equivalent of being WELDED to the tower. I'm loaded for bear and ready to kick ass tonight on 40M. Hear that Huz?? You getting on so we can hold court in the static?...Grin   Frank, will you have something to use tonight?


Jack/GT - How's that 2nd loop working out for you?

T


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« Reply #236 on: October 02, 2009, 04:51:43 PM »

The loops can equal the front-to-back (F/B)ratio of a three element Yagi, but will have a db or two less forward gain.



Just got down from a 190' climb. Got the other two sidearms installed. The Yagis are the equivalent of being WELDED to the tower. I'm loaded for bear and ready to kick ass tonight on 40M. Hear that Huz?? You getting on so we can hold court in the static?...Grin   Frank, will you have something to use tonight?


Jack/GT - How's that 2nd loop working out for you?

T



Tom and HUZ

Been working....no time to work on antennas this week.  Its supposed to rain tonight and tomorrow...we will see.  I hope to get something done, perhaps Sunday.  Might even try just supporting both from single top support and spacing out 20 ft at bottom.  I will listen for you guys tonight if I can.  Still on one loop (1.4 dBd gain or something like that).

73,  Jack, W9GT
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Steve - WB3HUZ
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« Reply #237 on: October 02, 2009, 04:59:48 PM »

The plots I posted below show a little over 10 dBi. You were seeing 11.5-12 dBi for a three element Yagi.

Quads do not have any "extra" gain when used as an array. The stacking gain obtained by a single quad loop over a dipole does not carry through in an array. With a single delta-loop, there is almost no gain compared to a dipole, so there would be even less of a reason for them to have "extra" gain in an array.

I'll be on early.


The loops can equal the front-to-back (F/B)ratio of a three element Yagi, but will have a db or two less forward gain.

You see that much difference in modeling?

I usually saw about 11.5-12 dbi gain for a 3el Yagi 1/2 wavelength above ground  -  and about the same for a 2el delta loop with its avg height = 1/2 wave above ground. (Same boom length)   I wonder why you are seeing 1-2db less?

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K1JJ
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« Reply #238 on: October 02, 2009, 05:31:31 PM »

I'll have to look at my model again.  I always thought the 2el delta was a good trade-off using one tower vs: a 3el Yagi, etc.

Anyway, I'm going grocery shopping now, so won't be back until at least 8PM. See ya on after that, OM.

T
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« Reply #239 on: October 02, 2009, 06:17:06 PM »

Just dialed in the antenna. dipole driven, loop reflector. VSWR flat at 7.150 with less than 2:1 at band edges.  US stations weak but just got a 59+10 from an IK6 and 58 from RN3ZDD running 100 watts. I should be able to get on tonight but a bit after 8:00.
I want to simulate the antenna I have. . The loop reflector is about 35 feet tall and about 150 feet of wire. I'll change it to a driven loop if I can get a good match.
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« Reply #240 on: October 02, 2009, 09:25:56 PM »

Running 100 watts on a low angle night with Tom Vu is like putting a 30 dB pad on the radio, but it was a good test.
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K1JJ
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« Reply #241 on: October 03, 2009, 12:19:15 AM »

Running 100 watts on a low angle night with Tom Vu is like putting a 30 dB pad on the radio, but it was a good test.

It was a fun night with Jack / W9GT  joining us earlier.   Much later after you signed out Chuck/ K1KW stopped by for a coupla hours.   The highlight of the evening was working a MOBILE in Iraq who was delivering the mail to the US military bases. He was on the road in an 18 wheeler in a military convoy... Grin   59+20.    The band was in the best shape I've heard in a long while.   

Keep up the antenna experiments, Frank.


What happened to the Huzman?



T
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« Reply #242 on: October 03, 2009, 12:23:53 AM »

THat mobile from Iraq was a kick  Grin

Some guess meter readings - when you were testing the low dipole, S9+10 on the yagi, about S-5 on the low dipole.  Chuck was about S8-S9.  So tonite u win over Chuck.

I gave a call when you paused for QRP but some 10 watter in G-land strapped me  Grin
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« Reply #243 on: October 03, 2009, 09:29:52 AM »

Those beams are really working for you Tom!  You were copying stations S-9 that I could barely hear.  Had lousy high noise level here as well with the rain in the area.  Frank, you were 20 over here, then you just disappeared.

73,  Jack, W9GT
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« Reply #244 on: October 03, 2009, 10:08:07 AM »

Jack you also faded way down. Most US starions are pretty weak. I'm going to add a second loop as a driven element today to see if I can reduce the noise. (if it doesn't rain) Many of the weak stations Tom worked were buried in static but in there. So as HUZ says, it is all about signal to noise ratio. The high angle attenuation only looks good with corner fed loops but I can't seem to get any good FB in simulation.
Last night I could see me getting in the way so decided to do some simulations.
TNX  for the help testing. I was good until the band went way long.
 
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K1JJ
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« Reply #245 on: October 03, 2009, 11:47:50 AM »

THat mobile from Iraq was a kick  Grin

Some guess meter readings - when you were testing the low dipole, S9+10 on the yagi, about S-5 on the low dipole.  Chuck was about S8-S9.  So tonite u win over Chuck.

I gave a call when you paused for QRP but some 10 watter in G-land strapped me  Grin


Hi Johnny -

Aw, too bad we missed you again. I must remember to pause specifically for YOU next time. I'll bet you wuda made the trip last night.  What callsign will you be using, something like "SV1/W3JN?"  That American Iraqi-mobile had a small whip and simple 100 w transceiver in his truck. He used the call YI9SLI - his home call is KB2SLI, so they obviously let them use their own suffix. I found a picture of him and posted below.  What a thrill.  (I was tempted to axe him about road landmines, but decided not to...   Shocked)

Frank, you shuda hung around later on - the angles started to go higher and Chuck's single Yagi at 50' was par with my stack into western Europe after about 10PM or so.  The farther middle east still showed a difference at times but it was less as the night went on.  I think the angles appear to be very low early on and slowly move higher throughout the night. That's the way it used to work on 75M in the past too.

Last night's results showed me the value of maybe putting in that 180 phase switching to get some energy up at 30 degrees for these special times.

Frank, now you have a baseline to improve on. I intentionally picked out some weaker stations to see you stretch - as well as some louder ones to get you some reports.   If you work on the system there, you will slowly get that S/N ratio improved. I saw the Huzman get to the point where he can hear about anything I can hear now, so it's just a matter of trying many things.  Get that beverage up as soon as you can too. I think Steve relies on his bev most of the time. Many times a TX antenna is not a good RX antenna. Though, I find my stack is at about par with the phased bevs on 40M, so I use both in diversity. However, last night for a while, the stack was MUCH better than the bevs, so I switched off the bevs for an hour or so.

Jack, OK on the cold there - hope you feel better. I think you will see a massive difference when you get up the second loop and generate a good f-b. That is the fastest way to improve your s/n ratio. After that, a bev will help.  I understand you had storm static over there - it was not bad here at all last night - one of the better nights in a long time, static-wise.

Hope to get on tonight. Might also try 75M for a while too.

It really was a lot of fun last night with many personalities dropping by throughout the night. I even heard someone going , "yallo, yallo" in the background a few times... Grin

Later -

T



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« Reply #246 on: October 03, 2009, 01:40:56 PM »

Tom,
I found a set up with two loops that will match 50 ohms. I will be heading out with a spool of wire soon. I think the Hot Rod Racal will end up on an RX antenna. It is a quiet radio and would work nice on a beverage. I'm hoping a loop driven element is quieter on RX. TR7 is not the quietest radio. It has a jumper set up that would allow using a different RX or a splitter would allow two receivers.
I know you were reaching out for the weak ones to make it a good test. I was working Russians earlier and a couple italian stations when the band was higher angle. Then I took a break and listened to Chuck.
I will be taking Peter to his game tonight. He can't play but he will help out. I might get on early.
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« Reply #247 on: October 03, 2009, 01:48:50 PM »

SV0/W3JN

That was probably me doing the "HAY-lo"  Grin
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« Reply #248 on: October 03, 2009, 02:31:21 PM »

John,
You can get a nice low angle of radiation with a corner fed Delta loop flat side down if you can find a single high support. Time to build another loop, it is raining. 
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« Reply #249 on: October 03, 2009, 03:14:22 PM »

SV0/W3JN

That was probably me doing the "HAY-lo"  Grin


Yeah, I think it WAS you!  It was more of a "Hay-lo" rather than "Yallo" said maybe 3-4 times and that's it. If so, you were about 5X8 and an easy copy. With that signal it wuda been easy last night, but difficult on a noisy static night.  If we're on that late tonight on 40M, (11PM local)  I'll give a few pauses for (SV0/W3JN).  Make a tape of it if you can.


Frank, you might as well go for the gusto - use two Racals and go dual diversity RX right off the bat, once you get the bev going.

T
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