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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 156999 times)
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WA1GFZ
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« Reply #300 on: October 08, 2009, 01:56:28 PM »

Jack it all seems possible till you consider that pesky ground under the antenna. I have tried by putting the delay line length as a variable in the simulation. I think I will start with 2 1/2 wave feed lines to get me to the ground and then play from there.
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Steve - WB3HUZ
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« Reply #301 on: October 08, 2009, 02:23:31 PM »

In the end-fire configuration, changing the phase will only change the gain (some), the F/B (potentially a lot) and the exact location of the null on the back side of the pattern. That's it. You cannot change the azimuthal angle at all. You can possible change the width of the azimuthal lobe slightly but not much.

I see no value in changing the phasing in the shack. The longer the phasing lines, the more reactive they are, the less the bandwidth and the greater the loss. If you want to null stuff out on receive, use a second antenna and a phasing box.
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K1JJ
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« Reply #302 on: October 08, 2009, 03:45:00 PM »

Just worked Mohammed / A71EL in Qatar at 3:30 PM local. He was about 5X7.  THREE hours before our local sunset.  Looks like 40M is opening early today.


Interesting thang is western Europe  appears to be medium-high angle at this time. There is only about 5-10db between the stack and low dipole on most western Euro - it's usually 20-25db at optimum times.

However, Mohammed was not copy-able on the low dipole, so mideast was probably low angle at 3:30PM.

T
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« Reply #303 on: October 08, 2009, 04:20:43 PM »

Steve I need to play with the simulator some more to make sure the stub is 9 feet which would put my switching 30 feet up the tower. I was just dreaming about variable phase doing anything constructive.
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Steve - WB3HUZ
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« Reply #304 on: October 08, 2009, 09:08:50 PM »

I'm thinking 40 might be open for DX 24 hours a day in the winter months.


Just worked Mohammed / A71EL in Qatar at 3:30 PM local. He was about 5X7.  THREE hours before our local sunset.  Looks like 40M is opening early today.


Interesting thang is western Europe  appears to be medium-high angle at this time. There is only about 5-10db between the stack and low dipole on most western Euro - it's usually 20-25db at optimum times.

However, Mohammed was not copy-able on the low dipole, so mideast was probably low angle at 3:30PM.

T
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WA1GFZ
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« Reply #305 on: October 08, 2009, 10:24:23 PM »

Ah brain feels good. Got a stub switching system like the HUZ machine to work with my configuration. RG11 off each loop 19.05 feet down to switch. Add 8.25 feet with end shorted for stub and drive the other. This gets me down close to the ground by flipping the long section with the short. Flat side down doesn't show quite the FB but that is life.
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K1JJ
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« Reply #306 on: October 08, 2009, 10:33:30 PM »

Ah brain feels good. Got a stub switching system like the HUZ machine to work with my configuration. RG11 off each loop 19.05 feet down to switch. Add 8.25 feet with end shorted for stub and drive the other. This gets me down close to the ground by flipping the long section with the short. Flat side down doesn't show quite the FB but that is life.


We all KNEW you'd finally settle on this config... :-)  It will work the best for you.


Yeah, Steve, 40M may never close to Eu, just like the all night roach motel.  I'll bet come Dec 25th you could hold a QSO with the G's right thru OUR local  sunrise into the afternoon.  It will be interesting to catch the Euro sunset for the first time. (At least for me)     Maybe 11AM local or so wud be the time to do it about that time.  I know that VE1ZZ claims to have done it on 75M from the VE1 Atlantic coast.

T

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Use an "AM Courtesy Filter" to limit transmit audio bandwidth  +-4.5 KHz, +-6.0 KHz or +-8.0 KHz when needed. 

Nothing like a new homebrew rig. Come into the shack, flip on the switches and everything works perfectly.

And, nothing like an old dog.
Steve - WB3HUZ
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« Reply #307 on: October 08, 2009, 10:35:29 PM »

Kewl beanz Frank. I love it when a plan comes together.
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WA1GFZ
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« Reply #308 on: October 09, 2009, 08:36:50 AM »

Things started to jell when I got home yesterday and lopped another 2.5 feet off the reflector. Resonant frequency came up another 50 KHz but the VSWR minimum came off 1:1. So this was telling me I needed a different feed Z away from 50 ohms. I started with the two loop sizes and tried 50 ohm stubs which didn't give me a good match. As soon as I changed to 70 ohm the sim would tune flat. Loops want to be about 27 feet tall and slightly smaller than HUZ design. Actually ended up close to my present driven element size.
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W9GT
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« Reply #309 on: October 09, 2009, 08:43:37 AM »

Ah brain feels good. Got a stub switching system like the HUZ machine to work with my configuration. RG11 off each loop 19.05 feet down to switch. Add 8.25 feet with end shorted for stub and drive the other. This gets me down close to the ground by flipping the long section with the short. Flat side down doesn't show quite the FB but that is life.

Just for grins, I decided to feed the second loop last night in a phased config.  Used a 33 ft sect. of RG8 to a tee.  The band was really hopping, so hard to really tell if much, if any difference.  Almost seemed like antenna was bi-directional.  Worked some Carribean stations, and several Europeans with good sigs, then 9K2YM called me and about scared me to death with a 20 over signal!  He was really booming in and he has a video link set up on his QRZ page to see his rig while working you. Great fun.

73,  Jack, W9GT
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Steve - WB3HUZ
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« Reply #310 on: October 09, 2009, 10:23:58 AM »

How did you come up with 33 feet for the phasing section?
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WA1GFZ
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« Reply #311 on: October 09, 2009, 11:39:58 AM »

34 feet close to 135 degrees. I also heard that guy last night around 6:00 Local and he was peaking 20 over. I have not tried to force feed the loops but had a crappy match with dipoles. I think if you have a long coax run the losses suck up the gain. I found my phased inverted Vee on 80 demonstrated good FB when the pattern was swapped but the reference dipole was stronger.
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K1JJ
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« Reply #312 on: October 09, 2009, 11:53:02 AM »

Worked some Carribean stations, and several Europeans with good sigs, then 9K2YM called me and about scared me to death with a 20 over signal!  He was really booming in and he has a video link set up on his QRZ page to see his rig while working you. Great fun.
73,  Jack, W9GT

I heard you in there holding court, Jack.  I tuned in when the 8P? Caribbean station called in and then the KB4's looking for signal reports.... Grin  Afterwards you were working Euro quite well.

Strange thing is when listening on the beverage, I cud hear the Euros you worked FB. But when I switched to the stack, there was a Mideast BC station covering up the Euros on 7145?   All I cud hear was you, barely.  It seems the stack has much more low angle than the bev AND the mideast was obviously coming in low angle.

I thought maybe the RX had an image problem, but found the same results on two other RX's.  Steve said he wants to work tandem wid me when this happens... HA!


BTW, I'm working on my second quad MRF-150 FET linear amp module. Gonna combine the two for 1200W out, all solid state. If it doesn't fry, I hope to have it running maybe today or tmw. Instant band switching with 1KW is cool.  I'll post some pics of it later.
T
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Use an "AM Courtesy Filter" to limit transmit audio bandwidth  +-4.5 KHz, +-6.0 KHz or +-8.0 KHz when needed. 

Nothing like a new homebrew rig. Come into the shack, flip on the switches and everything works perfectly.

And, nothing like an old dog.
WA1GFZ
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« Reply #313 on: October 09, 2009, 12:05:44 PM »

Tom, It might be a good idea to mount some large beer can caps near the amp if there is some distance back to the power supply. That switcher is rated for 35 amps so it should handle the extra load.
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W9GT
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« Reply #314 on: October 09, 2009, 12:14:41 PM »

How did you come up with 33 feet for the phasing section?

135 degrees per previous discussion/suggestions, 66% prop velocity.  I made it a little short to make up for connections.  Very crude and not anything all that precise, by any means.  Just fooling around with some concepts.  Certainly didn't see any earth-shattering results, but SWR went up, as expected.

73,  Jack, W9GT
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Steve - WB3HUZ
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« Reply #315 on: October 09, 2009, 02:23:34 PM »

Bear in mind, 34 feet will only be near 135 degrees when the SWR on the line is 1:1. I doubt you are getting anywhere near a 135 degree shift on the loops since their feedpoint impedance is far from 50 Ohms.

Unless you placed the phasing line after your impedance matching stub, then you should be in the ball park.


Quote
34 feet close to 135 degrees.


How did you come up with 33 feet for the phasing section?

135 degrees per previous discussion/suggestions, 66% prop velocity.  I made it a little short to make up for connections.  Very crude and not anything all that precise, by any means.  Just fooling around with some concepts.  Certainly didn't see any earth-shattering results, but SWR went up, as expected.

73,  Jack, W9GT
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WA1GFZ
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« Reply #316 on: October 09, 2009, 02:37:02 PM »

Jack you need to add a transfer relay so you can flip the pattern and see what it really does.
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WA1GFZ
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« Reply #317 on: October 10, 2009, 09:35:56 AM »

FYI, I was looking at an RG11 spec that said the VF was .75. I'll check again in case there is a foam version. Hope to do some antenna work today after the lawn dries a bit more.
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« Reply #318 on: October 10, 2009, 09:48:19 AM »

FYI, I was looking at an RG11 spec that said the VF was .75. I'll check again in case there is a foam version. Hope to do some antenna work today after the lawn dries a bit more.
Frank,

Are you combining the phasing section and the feed matching section in one piece of RG-11 or what?  I was using the matching section on the driven element and a phasing section of RG-8 from the tee to the director.   I know it is a mismatch, but works.  If you use two matching sections of RG-11 from each element to convert the ~100 ohms to 50 ohms, you end up with 25 ohms at the tee??  I think it stopped raining for awhile, maybe I can get out there and play with the antenna today.  Yes, I will use a relay on it eventually...perhaps the original arrangement of just using the second element as a parasitic element and switching from reflector to director is the best (easiest) solution for my situation.  I just like to try different things and experiment, hardly could be considered optimized at this point anyway...but I continue to get good reports.  Still need to improve the receive side...they hear me well, but it is a challenge hearing those 100 Watt or even 10 watt stations on vertical antennas that come back to my CQs.  Cool

73,  Jack, W9GT
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K1JJ
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« Reply #319 on: October 10, 2009, 10:52:44 AM »

There's two versions on RG-11/U.  The polyethelene? version  is .66 VF. That's the stuff I got and believe it's called 11/U.

The other is the foam, .78 VF  and is simply RG-11 or something like that. Stay away from the foam cuz of the power handling and the extra coax needed due to the VF. (assuming you don't need the extra length)   The foam is actually a tenth of a db better in loss IIRC.

I used two RG-11/U runs from the delta loops to the tower for the stubs.

You have to look carefully at the dealer's specs to be sure. I bought my poly RG-11/U from the Cableman.  His stuff was FB and the best price out there.

T
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Use an "AM Courtesy Filter" to limit transmit audio bandwidth  +-4.5 KHz, +-6.0 KHz or +-8.0 KHz when needed. 

Nothing like a new homebrew rig. Come into the shack, flip on the switches and everything works perfectly.

And, nothing like an old dog.
WA1GFZ
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« Reply #320 on: October 10, 2009, 12:19:16 PM »

That is what I thought, TNX. I avoid foam coax myself if possible. Today I plan to hang two new loops 136 feet long and 27 feet high. Also hang a quarter wave section of RG11 to the feed points at the bottom. Lots of simulation shows me this is a great match to 50 ohm source. So I willl drive one coax and hang a stub off the other.
The stubs at the end of a quarter wave section cost me a bit of FB but the antenna covers the whole band.
Jack I could also force feed it but all my simulation shows a weird Z so I need to look at some more simulations to see if it is worth doung. Guys running 4 squares make it play so still have not given up yet. At least both feed lines will be close to the ground so I can try different things.
My elements are about 5 feet shorter than the HUZ design with flat side down but I think my Z is back to around 100 ohms with the loops shorter height.  My present driven element is pretty close to 135 feet.
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« Reply #321 on: October 10, 2009, 04:04:57 PM »

Yes the foam stuff is good for VHF, but not really much advantage at HF.  I'm using the regular poly stuff, although the lines out to the tower (over 200' )are hardline which has foam dielectric.

73,  Jack, W9GT
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WA1GFZ
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« Reply #322 on: October 10, 2009, 05:28:35 PM »

Well, I spent the morning doing a bit more simulation and found my stub hanging off the loops is very close to the HUZ design. So spent the afternoon doing 2 loops with #12 wire with stubs hanging down. The only difference was I ended up with a shorted stub on the reflector coax and feed directly to the driven loop coax.
Hope to continue Sunday and maybe JS something by evening.
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Steve - WB3HUZ
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« Reply #323 on: October 10, 2009, 07:55:20 PM »

I use the RG-11 from ComScope. IIRC the VF is about 0.8. Ontario Surplus was selling 100 foot length for cheap at the Timonium fest this past spring, so I got some.
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WA1GFZ
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« Reply #324 on: October 10, 2009, 11:38:34 PM »

Steve,
Your write up is confusing you say you have 18.8 and 13.86 foot hunks of RG 11 but that would be longer then 1/4 wavelength electrical since 32.64 is a quarter wave at 7.16 MHz. I ended up with the first hunk at 18.6 feet of RG11 at .66 VF. Should I read your lengths as 18.82 X VF and 13.86 X VF? This would explain why I come up with a shorter total measured coax length.
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