Avanti Sigma4: An alternative view point

[Marconi]

Homer, I envy your ability to provide so much clear information in such short paragraphs... I should have stayed in Tech Writing class. :blush:

OK, well, I respect a good head-to-head test, same pole, coax, height, location etc., but I also respect daily living experience, so if you have gotten used to the performance of the Qv4k and could pull it down, (after jotting down some average signal strengths of local operators) and replace it with the 5/8 for a week or two, I'm certain you'd have an almost immediate preference, as I know I get a 'feel' for an antenna and am able to quickly notice losses when I hear someone I'm used to hearing with a certain static or tone quality and they are either louder & clearer or not so clear.
I'd like to hear you try such, but I don't know if that would be far too much hassle with that interesting home-brew tower of yours.

CDX 007, I mostly talk locally in the early morning when conditions are best out to 100 - 200 miles as conditions permit. Most of the operators around me are North and West and I'm always surprised when the long distance stuff (not skip) is working. In my experience this happens quite often too.

I have talked with this CB group of base operators almost every day since the early 90', and some as far back as the late 70's. Sometimes I get tired of hearing the same old stories.

I like to think I pay attention to what I hear too. However, hardly a day goes by that these same regulars are all over the place with their tone and quality of audio. Sometimes even their signals are up and down right before my eyes. Of course there are times that are better, but in my experience in all these years, I can't count on getting that "feeling" that you mention.

I have never been able to make comparisons when changing antennas, even if I could change it in 10 minutes. I would take a guess that very, very, few guys ever have a chance to switch or compare antennas at their location. The only way most ever get a chance to compare is just as you suggest, and changing antennas quickly, or have two antennas up on a switch box. Not many do either if the truth be know. It is a lot more work than most will admit as they're making their claims.

Right now I have an AstroPlane on a 40' foot pushup pole, and a A99 that is insulated from the 10' foot mast it's mounted on. The antennas are about 30' feet apart and the A99 hub sits below the peak of my roof which is less than 15' away. I'm sure from previous experience the roof blocks off some of my signals to the North. I have both antenna on a switch box. I can report that some local signals are exactly the same on both antennas, and at times DX signals are the same as well. Of course, there are noticeable signal differences at other times.

I believe what you tell us, but conditions here are constantly changing and always have with very few exceptions at my location. You are the luckiest radio operator I know to make such a claim to be in tune and get that "feel" with such qualities as you describe.

You asked Homer when he would get to testing his antennas, when do you think you'll get around to doing your comparison with your Penetrator vs. your Vector? I seem to recall it has been a while since you talked about your testing.

 

[Shockwave]

Frequent contacts at 200 miles on 11 meters would surprise me too. It doesn't seem to fit any of the typical propagation patterns for the band. Line of sight would be limited to just over 100 miles without extreme antenna height in the hundreds of feet. Skywave will not refract back to the ground at this short steep angle and groundwave will not propagate beyond the horizon at 11 meters. Conditions on this band have shown me a "cone of silence" in the 125 to 350 mile range for the last 30 years. Have others had a different experience?

 

[jazzsinger]

Frequent contacts at 200 miles on 11 meters would surprise me too. It doesn't seem to fit any of the typical propagation patterns for the band. Line of sight would be limited to just over 100 miles without extreme antenna height in the hundreds of feet. Skywave will not refract back to the ground at this short steep angle and groundwave will not propagate beyond the horizon at 11 meters. Conditions on this band have shown me a "cone of silence" in the 125 to 350 mile range for the last 30 years. Have others had a different experience?

Sounds like some form of tropospheric duct.i've seen it happen,but not frequently,seem similar style of propagation on 11m over sea water paths at about that range too,something i call sea ducting.but again infrequently.

could also be extremely short range sporadic e,which propagates from 190 - 1400 miles.

another possibility would be ionospheric or even auroral backscatter.

one things for sure 11m occasionally throws up some very strange propagation.but i doubt very much any of them would be frequent occurences at 11m.i think its safe to say mother nature doesn't always follow our rules.

 

[Marconi]

Frequent contacts at 200 miles on 11 meters would surprise me too. It doesn't seem to fit any of the typical propagation patterns for the band. Line of sight would be limited to just over 100 miles without extreme antenna height in the hundreds of feet. Skywave will not refract back to the ground at this short steep angle and ground wave will not propagate beyond the horizon at 11 meters. Conditions on this band have shown me a "cone of silence" in the 125 to 350 mile range for the last 30 years. Have others had a different experience?

SW, I agree. These contacts often surprise me as well, but I have been talking into this area West of Houston since back in the 80'. I can't explain the signals either, but most often when they come in real good the signals are stronger than the local signals I see. I figure that there is some sky wave that is working to improve some other ground type wave and in combination the signals are enough for contacts. Here in Houston we are at or less than 50 feet above sea level and those guys in San Antonio and Austin are said to be in the I-35 hill country corridor. In the 90's I use to talk to an old buddy up in Franklin, Texas, just about every day. He was about 130 miles from Houston, and I can't explain that one either. When I would visit him, I would get on his radio and talk to guys here in Houston in their mobiles. Another mystery.

My comments to CDX007 were meant to mention the current lack of suitable conditions for compassion testing, and how conditions have been that way now for several months. We have also had very little DX during this time, but we continue making contacts to the guys in the Austin, San Antonio area once a week and often more frequent.

And in this area, even when conditions are noted to be better for local contacts (the absence of DX), we more often than not see conditions varying all over the spectrum---which makes good testing difficult to impossible and for sure if you're trying to test switching antennas on the same system and support. In this area I don't think it is possible to ever get a "feeling" that goes to a standard signal or audio quality associated with his buddies, like 007 talks about.

I have no idea what Mother Nature does with the signals I generate and receive.

 

[Marconi]

Sounds like some form of tropospheric duct.i've seen it happen,but not frequently,seem similar style of propagation on 11m over sea water paths at about that range too,something i call sea ducting.but again infrequently.

could also be extremely short range sporadic e,which propagates from 190 - 1400 miles.

another possibility would be ionospheric or even auroral backscatter.

one things for sure 11m occasionally throws up some very strange propagation.but i doubt very much any of them would be frequent occurences at 11m.i think its safe to say mother nature doesn't always follow our rules.

George you might be on to something. The images below are from my re-model of Henry's Vector model. I changed the radiator length only---to 31.2' feet. Doing so placed the resonance way down in frequency at 22.6 mhz, but according to SW and Bob the gamma would take care of any reasonable mismatch. Both Henry's model nor mine attempt to include matching, and no mast of feed line was included. However, when I did add the mast I did not see the pattern or the max angle change at all. Other antenna factors did change, but not the pattern. In addition, when I made the antenna longer in steps up to 31.2' the pattern did change from a very good low angle max to the high angle max you see in the images.

View attachment IMG.pdf

So here is my idea for a question.

What if the antennas in this Texas story all produced similar patterns to the attachment above?

What if the higher lobes with the whopping large gains were good for sky wave reflections between Houston and the Austin/San Antonio areas?

And further suppose the other two lower lobes, with less gain and lower angles were low enough for line of site contact, but the signals from the lower angled lobes were just too weak to copy at the 100 - 200 mile range?

And then consider that all of these waves somehow arrive in phase at the same time between these stations---and thus produce a further improved signal into the areas in question?

I don't know much about this topic, but I have wondered how it happens here. Is something like this even possible?

 

[CDX-007]

CDX 007, I mostly talk locally in the early morning when conditions are best out to 100 - 200 miles as conditions permit. Most of the operators around me are North and West and I'm always surprised when the long distance stuff (not skip) is working. In my experience this happens quite often too.

I have talked with this CB group of base operators almost every day since the early 90', and some as far back as the late 70's. Sometimes I get tired of hearing the same old stories.

I like to think I pay attention to what I hear too. However, hardly a day goes by that these same regulars are all over the place with their tone and quality of audio. Sometimes even their signals are up and down right before my eyes. Of course there are times that are better, but in my experience in all these years, I can't count on getting that "feeling" that you mention.

I have never been able to make comparisons when changing antennas, even if I could change it in 10 minutes. I would take a guess that very, very, few guys ever have a chance to switch or compare antennas at their location. The only way most ever get a chance to compare is just as you suggest, and changing antennas quickly, or have two antennas up on a switch box. Not many do either if the truth be know. It is a lot more work than most will admit as they're making their claims.

Right now I have an AstroPlane on a 40' foot pushup pole, and a A99 that is insulated from the 10' foot mast it's mounted on. The antennas are about 30' feet apart and the A99 hub sits below the peak of my roof which is less than 15' away. I'm sure from previous experience the roof blocks off some of my signals to the North. I have both antenna on a switch box. I can report that some local signals are exactly the same on both antennas, and at times DX signals are the same as well. Of course, there are noticeable signal differences at other times.

I believe what you tell us, but conditions here are constantly changing and always have with very few exceptions at my location. You are the luckiest radio operator I know to make such a claim to be in tune and get that "feel" with such qualities as you describe.

You asked Homer when he would get to testing his antennas, when do you think you'll get around to doing your comparison with your Penetrator vs. your Vector? I seem to recall it has been a while since you talked about your testing.

I've also noticed some fading on some of the guys 60-80 miles from here, but that's usually the same basic amount and time of day, so I'm used to it.
If you tried using an iCOM 751A for a while you might understand better how I can get used to signal strength, it's metering is wonderful, though I painted the black needle with dayglo orange and backlighted the meter with 5 LEDs to brighten up the ugly yellowish factory lighting :glare: I still prefer it to the TS-930 & 940, & the FT-990 I've owned in fact the only Amateur rig/meter I've liked better is my old Yaesu FT-107M, but the iCOM is more frequency stable using a VCO instead of a VFO.

Anyway, I am wanting to get on the Saliut but it seems everyone I know has needed my help this month, installed a kitchen last week and am helping a friend move & clean the house he's selling this week. Oh, and I might be just a little lazy, too, :blush: ...especially when I get home dog tired.

Hey Marconi, I'm wondering if you've ever had a Penetrator up at your place and what performance you saw from it if you did?

 

[Marconi]

I've also noticed some fading on some of the guys 60-80 miles from here, but that's usually the same basic amount and time of day, so I'm used to it.
If you tried using an iCOM 751A for a while you might understand better how I can get used to signal strength, it's metering is wonderful, though I painted the black needle with dayglo orange and backlighted the meter with 5 LEDs to brighten up the ugly yellowish factory lighting :glare: I still prefer it to the TS-930 & 940, & the FT-990 I've owned in fact the only Amateur rig/meter I've liked better is my old Yaesu FT-107M, but the iCOM is more frequency stable using a VCO instead of a VFO.

Anyway, I am wanting to get on the Saliut but it seems everyone I know has needed my help this month, installed a kitchen last week and am helping a friend move & clean the house he's selling this week. Oh, and I might be just a little lazy, too, :blush: ...especially when I get home dog tired.

Hey Marconi, I'm wondering if you've ever had a Penetrator up at your place and what performance you saw from it if you did?

I'm pretty sure the meters or the AGC for my radios are messin' with the signals I get even though they are all about the same as best I can tell, sometimes I don't think they are close to right.

I wish someone would design and build an outboard RX meter that just read the signal coming in on the coax, before the radio and without all the circuit BS to pump the weak signals up and knock down the ones that are strong. I need a big face meter too, cause my eyes aren't what they use to be. I think Bob talked about it once before, but I haven't heard back on the idea. He may have been talking about something entirely different however.

007, don't get in no hurry on my account, I know we gota' do what we gota' do. I'm just waiting for some of you young guys to start giving us some good reports on what y'all are doing with your antennas. I wonder sometimes if our asking questions doesn't turn these young guys off. Heck, at my age I'm just talking most of the time, just trying to stay awake.

I wonder what ever happened to our buddy Starduster, he just dropped out after doing some real good work for us on the AstroPlane. Mac don't discuss his new Vector compared to his Wolf, and I know there are others that just quit posting. Dxer was just starting to do some real good work modeling and he seems to have stopped. CTStallion posted some of his models to consider and he stopped. He has been helpful for me to get started modeling with Eznec Demo. I like it, and it's fairly easy to get started. I don't know if what I can do is any good yet, but I seem to be able to learn something new every day it seems. I'll be presenting some ideas pretty soon I think, but it won't happen until I get a more advanced model of Eznec. The Demo version is very limited. And of all things, Bouty Monster, the link-stagater, has even become quite. I hope is is alright. I'm sure there are plenty of others as well.

I sometimes wonder if CB is not just dying on the vine. I live in Houston and I hardly ever hear anybody talking on the CB radio. Even channel 19 is silent at times. I do SSB on 39, and we still have our old group before daylight every day, but some of those buddies have dropped out there also. I see this hobby die down during the lows in DX, but it always came back. I'm not too sure about it doing so this time if DX does come back. DX is still spotty to dead here.

I get the feeling that antenna makers are dying out as well---with this slump in the economy I'm sure it is hard for them.

You know CDX, the Penetrator is one antenna that I don't recall being a big deal in this area. I can't say I knowingly ever talked to anybody using one. In fact, I've never seen one. I would like to have one of those new old refurbished ones I see on eBay every once in a while, but I have never been interested enough to spend the bucks. All of my antennas seem to me to work good enough around here, and I look around at all the old antennas I have and I wonder why. Of course when I'm up to it physically I like to try different ones from time to time.

I think some piss head is jackin' with the forum right now. I keep getting a block on entering WWRF and it looks like the notice of being banned. Some shit heads just don't have a clue how to use their God given talents. I'd like to squeeze their little chicken neck and slap em' and listen to em' squeal like a pig under a gate.

 

[CDX-007]

Marconi, I'm afraid I'll have to disagree with nothing in that last post of yours.

And what conditions? This has certainly been one wimp-out of a so-called skip cycle.

Damn if the weather is getting back into the high '90s again for this full moon or I'd be up there tomorrow with radial cone in hand. Can't touch the dang metal mast when it gets that hot.

I also have an old original SigmaII 5/8 I bought new in '75 as a Sophomore and sold it to a friend after I decided the Penetrator was the keeper of the two, but I got it back about 4 years ago and it's just sitting in storage. I should do something with these antennas I have stored, like the original Astroplane I promised Bob85, it's still just awaitin' my energies to break it down and get it packed for shipping, if he still wants it.

The antenna I really am 'jazzed' about (that's for you, George ) fabbing up is a phased dual ½ λ collinear which I suspect might 'take the cake'.
I've already got the mechanics of a 36' tall antenna worked out and I hate to say it but that's the fate befalling the Saliut after the test.
- I can already hear the sound of the hacksaw.

Hey Marconi, why not email & PM those guys and ask them if they might want to come back around where they're missed?

73

 

[jazzsinger]

I don't know much about this topic, but I have wondered how it happens here. Is something like this even possible?

Here's a link you might want to check out about ionospheric backscatter and its frequency around 10/11m Eddie.

HF Backscatter off Travelling Ionospheric Disturbances Identified with Pactor-II

Another point i noticed about your comms with the Austin/San Antonio areas was i believe there is hills between you and them,which could also bring refraction from the hilltops into play,if that is the case then line of sight signals that would normally be shooting off into space could well be refracting back to earth.

There is so many different phenomena involved at the top of the hf band its hard to pinpoint exactly what is letting you make those extraordinarly long contacts.

i don't doubt you did it,as a few years back i was on Ardrossan sea front in scotland and i could clearly hear a station in Blackpool england who was static mobile on the promenade, i was getting him s2 r5 and i was only using a barefoot president jackson and sirio hp4000 magmounted antenna,the distance between us was 144 miles as the crow flies. of which at least 40 miles is over land which is very hilly and around 100miles is via a sea path.

i believe the low angle reflection from the sea was then being refracted by the hills as there is no way a clear line of sight path could be established by two stations sitting static mobile at sea level,there was no ionospheric propagation at the time or sporadic e, the band was dead apart from the station in blackpool, and another maritime mobile station who was halfway across to northern ireland and he could also hear the guy in blackpool as i qso'd with him all the way to n.ireland.sadly neither of us could get back to the station in Blackpool as he was being swamped with stations from the republic of ireland which is right across the irish sea from blackpool, maybe had i had a bit more power at my disposal that day i could have got inbetween the stations from the republic of ireland.

even running power from the local hilltops in my city (Glasgow) where i can work fantastic distance via line of sight,i've regularly worked cumbria in northern england from there (which incidentally no-one in the valley below me could hear no matter which antenna they were using) and also the border area of the republic of ireland, there is no way i'd get into Blackpool which is about 50 miles south of cumbria. so something else was responsible for being able too hear blackpool,the guy in blackpools signal stayed at a steady s2 for over 4 hours with absolutely no fading whatsoever, which had there been fading would most likely indicate sporadic e.

I've seen plenty other freak occurences on 11m over the years to never rule out anyones claims no matter how far fetched they may seem at first glance.

As for this skip cycle,its been real lame over here too,i can't recall a time in the last 30 years f layer propagation has been so poor,even sporadic e this year wasn't as good as previous years.

 

[HomerBB]

5/8 ready to go

Got the 5/8 put together today. naturally, the thing is made of some temporary materials until it is decided whether it will be worthy of permanence.
Looking at the photos you can see the coil is 1/4" copper tubing, and the GP radials are made of metal tape wrapped around bamboo garden stakes. I opted for horizontal GP this time instead of drooping. My decision was based on the fact that the most applauded designs in current use (I10k, Mr Coily, Merlin, etc) employ that style and I wanted to make a relatively comparable test.

Soldering the tap point and some sealer at a couple critical points is all I need to do before raising the 5/8 up. Sunday afternoon I should be able to swap the two antennas out and run the 5/8 alternatively to the Qv4k for testing. Honey-Dos tomorrow . . . When I get it in the air I'll get some full size photos of the antenna.

I tapped the coil at the fifth wrap up from the bottom and found the SWR to be a little higher on 40 than 1. I moved the tap to the sixth wrap and it is flat across the 40 channels, 26.965 - 27.405.

I will not know the how widebanded the 5/8 is until I get it on the tip over mast and connected to a multi-banded radio. I set up the SWR on an 8' pipe above a 6' step ladder.

I will be posting my empirical test results on this thread, and comments on the usefulness of the tip over tower on that thread (Tip-Over Wooden Homebrew Tower). Bear in mind that I do not have the equipment others of you have, so my reports will have to be of what I am experiencing on my S-meter, hopefully on other stations from mine, and on the audio differences and/or similarities. Suggestions are welcome, after all this has been a forum wide project. I will execute any that seem possible and have merit. I'll need help to sort things out as we go.

Perhaps some DX will show up for the record.

 

[HomerBB]

antenna specs:

5/8 length ---------------- 22.5' over all
vertical diameter -------- 1 1/4" bottom - 1/2" top
coil diameter ------------- 2 5/8" inside
coil tube diameter ------- 1/4" copper
coil length ---------------- 5" end-to-end wraps
# of wraps --------------- 10
tap point ----------------- # 6.5 wrap
length of copper tube --- 9'
GP radial lengths -------- 9' each x 4
Center tap wire ---------- #14 solid copper

Materials used for vertical were pool cleaning aluminum pole, extension paint pole, and part of a crutch. The GP radial hub is a poly cutting board with radials secured in 6" pieces of copper tube clamped to the hub.. Each tube/radial is joined to the other with metal banding. The coax is attached by a SO-239 through the cutting board. The shield current is carried to the GP radials via multiple layers of aluminum tape through which the SO-239 is mounted.

I have no idea what the actual efficiency of this antenna is in terms of software modeling. Perhaps someone might be interested in running it. I shudder to think of having to redo anything. I hardly think it matters considering the Vector 4000 has resisted numerous efforts at modeling, and my Qv4k is flying by the seat of its pants, too.
Ultimately this may simply prove to be a duel between two homebrews by the crude dude.

 

[HomerBB]

Finally got the 5/8 into the air last night as the sun fell. Preliminary results are encouraging, but limited. Ears within 20 miles seem good and reports from other stations indicate I may be doing as good, perhaps better with this antenna over the Qv4k.

If this proves true I believe the cause will have to be because I have not optimized the Qv4k due too not having the proper equipment. The construction of a 5/8 wave is much more basic and falling into a good design is much easier.

I will begin to compile data in terms of audio reports, and S unit readings here and to other stations. i know radio S/RX meters are not precision instruments, but I believe they are usable references when they are from stationary stations on the same radios each time.

Some modifications to the 5/8 were done before I sent it up: after a lot of wind here in the area I decided it needed some changes to avoid disaster.

 

[Toll_Free]

Frequent contacts at 200 miles on 11 meters would surprise me too. It doesn't seem to fit any of the typical propagation patterns for the band. Line of sight would be limited to just over 100 miles without extreme antenna height in the hundreds of feet. Skywave will not refract back to the ground at this short steep angle and groundwave will not propagate beyond the horizon at 11 meters. Conditions on this band have shown me a "cone of silence" in the 125 to 350 mile range for the last 30 years. Have others had a different experience?

On a regular basis, I can talk to 360 in Squaw Valley, Ca.

He's approx 4K feet.

I'm at 6000 feet, and we talk. At will. I'm on a (how I found the thread) Sigma IV.

He runs a 3 element beam, homebrew I BELIEVE!

Amplitude, Altitude and Attitude. AAA of CB.

--Toll_Free

 

[Shockwave]

On a regular basis, I can talk to 360 in Squaw Valley, Ca.

He's approx 4K feet.

I'm at 6000 feet, and we talk. At will. I'm on a (how I found the thread) Sigma IV.

He runs a 3 element beam, homebrew I BELIEVE!

Amplitude, Altitude and Attitude. AAA of CB.

--Toll_Free

I'm not sure how far that is from your location. However, you will notice that the approximate distances I mention specifically exclude antennas mounted hundreds of feet above average terrain. With antennas at 4,000 and 6,000 feet this would certainly extend the line of sight coverage area significantly.

 

[Toll_Free]

I'm not sure how far that is from your location. However, you will notice that the approximate distances I mention specifically exclude antennas mounted hundreds of feet above average terrain. With antennas at 4,000 and 6,000 feet this would certainly extend the line of sight coverage area significantly.

According to GoogleEarth Ruler Dimensions, 340 miles. I'll live with that on 250 pidgeons!