considering an M400 starduster. whats the deal?

[Marconi]

right now a local is trying to cure CMC on a new imax install, the usual cures that worked on his a99 don't seem to work, tweaking choke turns does nothing you can detect from rfi changing level,
things that work most of the time don't work for everybody.

According to Henry's post the other day all you have to do is get the perfect choke and they are really easy to determine the technical requirements, and then the guy will never have another worry.

Bob, I have an idea to consider. I've even posted this idea...why IMO some of the Solarcon antennas act bad.

You can try a forum search...if I posted the idea since the last forum update the thread/post should still be in the history. If you find it...just don't tell the guy my ideas are dubious at best. (hehe)

Did you tell the m8 to get a real antenna.

 

[Marconi]

I don't think you deliberately try confusing me with ground types Eddie,
clearly ground type effects the pattern at that height,

If you are confused Bob, don't look at me...I was just following the new trend in CB modeling presentaton practices to help make my models really look goooooood (hehe) like all the other models we see here on the WWDX.

You still don't get it.

 

[The DB]

Consider that I must have made a mistake in the model like DB is claiming.

When in this thread did I claim that you made a mistake? I don't recall doing that and I went back and looked at mt recent posts, did I miss something?

Based on your comments here, which I agree with, you need to ask DB why he chooses to set his models over "Very Poor Ground," which IMO makes models at their very obvious best...and folks just don't know the real difference and why.

The quick answer is, I'm not modeling over "very poor ground", I am modeling over "moderate ground". As we have discussed in the past our software sees this differently. Their is also a "poor ground" in 4nec2, which I don't tend to use. So, who's software is more accurate with naming these grounds?

Their are two reasons I don't use "average ground", one of which is 4nec2 defaults to moderate ground when a non-perfect ground is selected. I do not know where our programs got their naming schemes, and why they are different, and I cannot tell you which one is more accurate. Here is the thread where Ghz24 and I talked about the ground in 4nec2. Essentially we came to the conclusion that the results of the so called average ground, at least for the models we tested, were in fact the most extreme results, and thus anything but average.

Now how I model has changed quite a bit since then, and its possible that I should reconsider ground types when modeling as I have definitely learned more about grounds in general, and I would call what I talked about back then... Incomplete.

Here is what is available to me for the different ground qualities.

• Poor: conductivity .001: dielectric constant 5.
• Moderate: conductivity .003: dielectric constant 4, and this is the default that the software goes with.
• Average: conductivity .005: dielectric constant 13.
• Good: conductivity .015: dielectric constant 17.

After these four I have a bunch of different surfaces to choose from, although I rarely look at these grounds.

• Dry, sandy, coastal: conductivity .001: dielectric constant 10.
• Pastoral hills, rich soil: conductivity .007: dielectric constant 17.
• Medium hills and forest: conductivity .004: dielectric constant 13.
• Mountainous hills < 1000m: conductivity .002: dielectric constant 5.
• Rocky, steep hills: conductivity .002: dielectric constant 13.
• Fertile land: conductivity .002, dielectric constant 10.
• Rich agric land, low hills: conductivity .01: dielectric constant 15.
• Marshy land, densely wooded: conductivity .0075: dielectric constant 12.
• Marshy, forested, flat: conductivity .008: dielectric constant 12.
• Highly moist ground: conductivity .005: dielectric constant 30.
• City industrial area: conductivity .0001: dielectric constant 3.
• City industr. average att.: conductivity .001: dielectric constant 5.
• City industr. maximum att.: conductivity .0004: dielectric constant 3.
• Fresh water: conductivity .001: dielectric constant 80.
• Fresh water 10°/100 Mhz: conductivity .001, dielectric constant 84.
• Fresh water 20°/100 Mhz: conductivity .005, dielectric constant 80.
• Sea water: conductivity 5: dielectric constant 81.
• Sea water 10°, up to 1 GHz: conductivity .004, dielectric constant 80.
• Sea water 20°, up to 1 GHz: conductivity .004, dielectric constant 73.
• Sea ice: conductivity .001: dielectric constant 4.
• Polar ice: conductivity .0003: dielectric constant 3.
• Polar ice cap: conductivity .0001: dielectric constant 1.
• Arctic land: conductivity .0005: dielectric constant 3.

Some of these are oddly specific.

Anyway, those are the options I have, and I have experience that the so called "Average ground" is anything but average. So you guys tell me, in these cases what should I use and why?


The DB

 

[Marconi]

considering an M400 starduster. whats the deal?

Bob, for sure try again checking the link to my post above. You say you can't check a model out close, because you have never made a model. Just humor me and check out PDF #2 again. It shows my version of Steve's last SD'r model in his video and the same model with my idea for a FIX for the CMC issue plus a lot more. Sorry, I should not have included PDF #1 in my post.

Again, my idea here shows my version of DB's -80* degree SD'r . The second model in this PDF is my version with a FIX for the CMC issue that works as it should IMO.

See if this is fair. If I'm wrong here...I have confidence it will all come out in a reasonable discussion about these results.

I repeat both antennas are the same antenna. Again the only thing different is the FIX I added, as I said above, I used a model similar to Steves -80* degree model he showed us in his video. Here he also tell us this model is very similar to a CFHW, but I disagree because the match he shows in his video is not for a CFHW dipole. Again, just look at the Source Data report...and you will see the match is not that of a CFHW, like Steve suggested.

If you're not lost in the confusion of your own thinking for a moment, try checking my FIXED model at the bottom.

Again, both models are the same antenna...the only difference is my FIX. I even kept the choke at the top of the mast for my model that does not work.

Here is the big challenge to understanding my post. Take a close look at the Source Data report for my FIXED model, and you will see the matching info is very similar to what we should see on a CFHW dipole. It is a little off because the SD'r with -80* degree radials is not symmetrical to a CFHW.

Then after you have a handle on the difference I've been talking about since Steve posted his video...,maybe you can see the point I raised here. I also asked Steve to show us his currents for his SD'r with -80* degree radials on his model.

If he shows his model with no currents and a match that is similar to a CFHW dipole, with a nice new low angled pattern, and shows us again what he tells is the description for such a SD'r with radials slanted down close to the mast...then I will shut up talking about this issue.

 

[Marconi]

DB here is my Eznec Ground Description reference and feature screen showing the same or very similar values for similar word descriptions...used in 4NEC2 for Conductivity and Dielectric Constant.

Steve, for my vote...you do what you want...this is a choice we have in modeling. I'm just trying to make it clear what it really means for folks that are interested. IMO, this is a feature that impacts the pattern in a major way and as such can be abused.

 

[Marconi]

When in this thread did I claim that you made a mistake? I don't recall doing that and I went back and looked at mt recent posts, did I miss something?

Here you go Steve. I followed up asking for a little advice about how you do a choke in 4Nec2, and if you can't recall you answer...I accused you of just giving me a lecture and this just happened maybe yesterday.

Marconi, I'm glad that that fixed the problem you were having. You essentially made a makeshift inductor, which, like on an antenna, will change the electrical length of the outside of the feed line to a length that did not cause said problems. I'm happy that it fixed your issue, but that is not a choke, however much it resembles one to some people. What you did can be a two way street, in one installation it may fix a CMC issue, while in another doing that can actually cause a CMC issue that didn't exist before. The difference between what you are talking about and a properly designed choke is the choke won't have the potential problem of adding CMC's to the feed line if it wasn't needed to begin with.

The DB

I wonder if you men don't have too much on your plate to remember and sometimes can't. Something this 80 year old man still does pretty well considering.

Folks, don't accuse me of bragging, I'm just saying what is on my mind unless that is against the rules.

 

[The DB]

Here you go Steve. I followed up asking for a little advice about how you do a choke in 4Nec2, and if you can't recall you answer...I accused you of just giving me a lecture and this just happened maybe yesterday.

With all due respect, their is a big difference between saying you were wrong and what I typed.

The easy way is to put a lumped resistance where the choke is on the antenna model. A properly made air wound choke will have in the neighborhood of 8000 ohms of impedance on the frequency it was designed for. However, with this method you should be careful, such an air wound choke will have a very narrow bandwidth with this impedance, something in the range of a MHz or less, so a bandwidth scan that is to wide will not be accurate as it moved out of the bandwidth of the choke, especially if it gets far enough away from the frequency the choke was designed for that it will not only not be effective, but it may even be detrimental. This method is also the only way to simulate a ferrite choke, which you won't have as much of a bandwidth issue to worry about as ferrite chokes cover a very wide bandwidth. A ferrite choke will generally have a resistance between 1500 to 2500.

The hard way is to actually model an air choke, model the coil, conductor and wire covering and all. This isn't always so easy to do as you need to know all of the details about the coax. As a matter of fact it is a pain in the ass, and when done is only accurate to a single specific brand and model of feed line, but it is doable and has been done, although I am likely not going to do this again.

most folk have average ground, nobody has perfect & very few have very poor,
sticking to avg makes comparing models much easier,

If you are confused Bob, don't look at me...I was just following the new trend in CB modeling presentaton practices to help make my models really look goooooood (hehe) like all the other models we see here on the WWDX.

As the only other current active modeler on this forum, that is not why I use a different ground. As I stated above, I don't think that the so called average ground that the modeling software presents is as average as people seem to think it is. I posted a link above to a thread where I discussed this with GHz24, and we came to the agreement that not only was average ground not average, but was actually the only ground when compared to 4nec2's poor, moderate, and good grounds that was significantly different from the others across several models.

Steve, for my vote...you do what you want...this is a choice we have in modeling. I'm just trying to make it clear what it really means.

It looks to me like we are comparing apples and oranges here. Your very poor ground has a lower conductivity than my moderate ground, while the dielectric constant is nearly the same. Because of this I think calling the Moderate ground that I am using the same as the Very Poor ground that you say I am using is a bit much, but that is just an opinion. Like I said above, I would need to do a study of grounds and their effects to know for sure. You may be right, and their may be almost no real difference, but I think my moderate ground, with it being three times as conductive as your very poor ground, is enough to say that at the very least they are not the same thing.


The DB

 

[Marconi]

It looks to me like we are comparing apples and oranges here. Your very poor ground has a lower conductivity than my moderate ground, while the dielectric constant is nearly the same. Because of this I think calling the Moderate ground that I am using the same as the Very Poor ground that you say I am using is a bit much, but that is just an opinion. Like I said above, I would need to do a study of grounds and their effects to know for sure. You may be right, and their may be almost no real difference, but I think my moderate ground, with it being three times as conductive as your very poor ground, is enough to say that at the very least they are not the same thing.

Somebody in the link above with GHz24 used my handle as though I was in the discussion. The only thing I know about this is what you've referred to a time or two. I don't recall anybody asking me to consider a standard in that regard.

For me, like a fool, I assumed if Eznec had a ground choice called "Average" so I used it...until guys started telling me my models sucked compared to your models.

Who beside me where you interested in establishing a standard for the ground used here?

Steve, I believe you need to redo your in depth study of ground choices again. Here are patterns of a model set at the values noted in pencil. Which of these 4 look similar to your highly trained eyes? I'll give you a hint...the first pattern is "Average."

Frankly, I don't care, like I said above. If you use your Moderated, I will use my Very Poor.

 

[The DB]

Somebody in the link above with GHz24 used my handle as though I was in the discussion. The only thing I know about this is what you've referred to a time or two. I don't recall anybody asking me to consider a standard in that regard.

You were mentioned twice, once where ghz24 asked you a question in his first post, and once where I said I think you use some form of average ground. As I recall I was surprised that you didn't take part.

For me, like a fool, I assumed if Eznec had a ground choice called "Average" so I used it...until guys started telling me my models sucked compared to your models.

I started that way with 4nec2, until that discussion with ghz24. The only difference is I had to choose average ground every time as 4nec2 defaults to moderate ground.

Who beside me where you interested in establishing a standard for the ground used here?

I was interested in no such thing. I was only mentioning that I didn't use the Average ground options, and their were reasons for it that had nothing to do with showing good results. My entry into that conversation was meant for both you and bob. If I would have known it would have turned into this I wouldn't have said anything.

Steve, I believe you need to redo your in depth study of ground choices again.

Fair enough. I have learned more about grounds in general so I have more context to factor into said study. I wouldn't be looking at the listed grounds themselves, but the individual effects of conductivity and the dielectric constant and how they interact with each other. As time permits I am actually doing a forerunner study as we speak comparing the 4nec2 Fast, Mininec, Real, and Perfect grounds. Nothing in this study touches the earth below. I also want to study the actual antenna models with a direct connection to the earth. Then and only then will I do the study comparing ground qualities and their effects on antennas.

Which of these 4 look similar to your highly trained eyes? I'll give you a hint...the first pattern is "Average."

I never called my eyes highly trained. More experienced at looking at models compared to someone who has not had the modeling experience we have, sure, but not highly trained. That being said, to some people those two things are the same. Unless you are going to tell me someone who has never seen the results of an antenna model will see everything that you or I see when it comes to modeling?

Also, you are using one antenna model, we compared many, and in several cases average ground was distinctly not average. No other ground type had that happen, so questions arose and we agreed on the matter. Strangely, I think that thread was the last thread he posted in, or at least very near.

Frankly, I don't care, like I said above. If you use your Moderated, I will use my Very Poor.

Do what you think will produce the most accurate results. Anything other than this and it becomes you who is manipulating results.

I, personally, don't trust the Average ground. One single example of a model won't change the fact that I have seen several models of various different antennas do something completely different when it comes to average ground, then go back to looking like what poor and moderate grounds were doing when I moved up to good ground. So with my statement of creating models that produce the most accurate results, what am I to do, use a ground type that I have reason to not trust just to make someone else happy?

Are you really asking me to be dishonest with my modeling just so they match your models? And then essentially threaten to be dishonest with your models just to try and make them match mine if I don't? If you are going to play this game, how can you expect anyone to trust your models. I mean, you don't even have a technical reason to make such a change in your modeling practice, by your own admittance you are doing this simply to make the models we produce look like each other.

I mean, you don't even seem to be trying to understand where I am coming from, then you think that the one model that you made that doesn't have the effect I am talking about somehow overrules all of the models I have seen with this effect?

I am disappointed in your shallowness and lack of honesty on this matter.


The DB

 

[Marconi]

You were mentioned twice, once where ghz24 asked you a question in his first post, and once where I said I think you use some form of average ground. As I recall I was surprised that you didn't take part.

Steve, I don't remember a thing about the thread between you and GHz24. Another member posted a comment, maybe GHz24 was asking him the question. The only recollection I have of GHz24 form the past was when I think he posted a model. I chatted with him at some point, but I don't recall any of it.

I started that way with 4nec2, until that discussion with ghz24. The only difference is I had to choose average ground every time as 4nec2 defaults to moderate ground.

The average in Eznec may well be a default too. Other than being aware of the feature I never paid it much attention, until I started realizing your patterns started looking different..and were always showing more gain at lower angles than my models. You will likely deny it, but I think I asked you several times what setting you used. I don't recall a response.

I was interested in no such thing. I was only mentioning that I didn't use the Average ground options, and their were reasons for it that had nothing to do with showing good results. My entry into that conversation was meant for both you and bob. If I would have known it would have turned into this I wouldn't have said anything.

You sound pretty sure about this. The only thing I know about you and GHz24 talking about grounds in that thread is what I just read and you referring this him with grounds in mind. Maybe this comment below will help refresh your memory about what you said back then.

Anyway, what I would recommend is a de facto standard that we modelers can use for said ground for posted models, I would recommend the real/average set as that is what I tend to use unless stated otherwise. Or we can opt to just note it every time we post a model. I'm pretty sure Marconi also uses average ground of some type for the most part as well with his EZnec models.

Steve, when you respond to your post here ^^^^^^^^^^^^^^^ I bet you'll tell me what you said above is not what you meant, right?

Again, I don't remember this thread even though GHz24 spoke his words as if I was in the discussion. This is a very small issue for me...but it just shows how simple words can cause friction among folks and you should just take it all in stride rather than get all worked-up about it.

Are you really asking me to be dishonest with my modeling just so they match your models? And then essentially threaten to be dishonest with your models just to try and make them match mine if I don't? If you are going to play this game, how can you expect anyone to trust your models. I mean, you don't even have a technical reason to make such a change in your modeling practice, by your own admittance you are doing this simply to make the models we produce look like each other.

NO Steve, that is not what I meant.(hehe) I'm sorry if you took my words that way.

I mean, you don't even seem to be trying to understand where I am coming from, then you think that the one model that you made that doesn't have the effect I am talking about somehow overrules all of the models I have seen with this effect?

You typically leave me wondering and this is just another case. I told you I have never considered in depth or otherwise regarding ground issues in modeling. You did tell me that you were interested in how grounds worked in modeling, and I don't doubt that. As I said above...my making a big effort in-depth study is not on my bucket list. In the past, the issue also wasn't on my radar...except maybe for a brief post or two explaining what I did regarding grounds. That was probably a word DEMO.

I am disappointed in your shallowness and lack of honesty on this matter.

This is just about modeling DB. I could ask you for permission to do my models, but I've already committed to Henry to ask his permission to make post. I predict you'll get over your disappointment.

I, personally, don't trust the Average ground. One single example of a model won't change the fact that I have seen several models of various different antennas do something completely different when it comes to average ground, then go back to looking like what poor and moderate grounds were doing when I moved up to good ground. So with my statement of creating models that produce the most accurate results, what am I to do, use a ground type that I have reason to not trust just to make someone else happy?

Maybe you ought to do a video on the subject. Show us exactly what your concerns are about Average vs. Moderate. Maybe, it will turn out better for you and take some of the pressure off. I believe situation causes your disappointment which is directly due to me discussing my views on the subject. Grief is not health. B

 

[bob85]

I never realised average could be not so average, or that different software uses different values for what sounds the same but is not,

i have farm land in most directions, i presumed it was about average,
looking at DB's chart that's not average ground or even close.

 

[The DB]

Steve, I don't remember a thing about the thread between you and GHz24. Another member posted a comment, maybe GHz24 was asking him the question. The only recollection I have of GHz24 form the past was when I think he posted a model. I chatted with him at some point, but I don't recall any of it.

He is the one who made the nec2 v4k model that Henry posted for us when he released his report. He also talked about a common models database of different antennas meant for a reference, and he and I both added models to a thread for that. He wasn't around very long though.

The average in Eznec may well be a default too. Other than being aware of the feature I never paid it much attention, until I started realizing your patterns started looking different..and were always showing more gain at lower angles than my models. You will likely deny it, but I think I asked you several times what setting you used. I don't recall a response.

I won't deny the possibility that you asked, all I can say is I don't remember, but its not like I was keeping anything secret about this.

You sound pretty sure about this. The only thing I know about you and GHz24 talking about grounds in that thread is what I just read and you referring this him with grounds in mind. Maybe this comment below will help refresh your memory about what you said back then.

Anyway, what I would recommend is a de facto standard that we modelers can use for said ground for posted models, I would recommend the real/average set as that is what I tend to use unless stated otherwise. Or we can opt to just note it every time we post a model. I'm pretty sure Marconi also uses average ground of some type for the most part as well with his EZnec models.

Steve, when you respond to your post here ^^^^^^^^^^^^^^^ I bet you'll tell me what you said above is not what you meant, right?

Again, I don't remember this thread even though GHz24 spoke his words as if I was in the discussion. This is a very small issue for me...but it just shows how simple words can cause friction among folks and you should just take it all in stride rather than get all worked-up about it.

Oh no, when I said that I meant it. However, that was the opinion expressed in my first post in that thread, an opinion from before the experimenting that we did. When looking at my last posts in that thread you will see my position on the matter has changed. Here is one of ghz's posts, and my response to it, the last two posts in that thread.

I originally picked average figuring it was just that, average.
due to my recent comparisons it became obvious that average
is far from average.
"Average" values consistently fall outside the range defined by good and poor
How can average be at one extreme not in the center ?
I think we must discard average as flawed in definition at least.
I reluctantly (most my models are already over average) suggest moderate.

At the moment I am in agreement with this. As far as ground conditions go, moderate seems to be much closer to an "average" than "average ground".

I have been toying with the idea of modeling a few test antennas over the rang of given ground types, manually controlled, and seeing how various aspects affect the output, and using that data to make my own version of "average ground" that is closer to an average...

With this, you can see that with testing that was done, not just me but the two of us, who looked at modeling evidence presented in that thread, changed our minds about using Average ground as the standard.

If you are going to take something I said as a conclusion from a thread like that, can you at least quote what I said after the tests were done? Its all in the context.

NO Steve, that is not what I meant.(hehe) I'm sorry if you took my words that way.

Then I apologize for the over reaction.

You typically leave me wondering and this is just another case. I told you I have never considered in depth or otherwise regarding ground issues in modeling. You did tell me that you were interested in how grounds worked in modeling, and I don't doubt that. As I said above...my making a big effort in-depth study is not on my bucket list. In the past, the issue also wasn't on my radar...except maybe for a brief post or two explaining what I did regarding grounds. That was probably a word DEMO.

I am interested in how grounds work. I have been doing a lot of reading when it comes to grounds in modeling lately. It turns out all of them have their flaws, some of them more than others, and I'm not even to the point of looking at the ground quality settings yet...

This is just about modeling DB. I could ask you for permission to do my models, but I've already committed to Henry to ask his permission to make post. I predict you'll get over your disappointment.

Lol funny, you or anyone ask me for permission to make a model? I would likely say no, not because I though you shouldn't make such a model, whatever it is, but because you are putting what you do in my hands. Hell, if your going to willingly give me that kind of power over your life, I may as well put it to use right?

Maybe you ought to do a video on the subject. Show us exactly what your concerns are about Average vs. Moderate. Maybe, it will turn out better for you and take some of the pressure off. I believe situation causes your disappointment which is directly due to me discussing my views on the subject. Grief is not health. B

Perhaps in time. That is if the study I would like to do on ground quality confirms and warrants such a thing. Unfortunately I have been a bit strapped for time when trying to get the needed data for my current study. And the study on ground quality will dwarf what I need for my study on the different grounds available in 4nec2... I sit down every day and gather data for a while. A little at a time, and eventually I will have all I need for this study and can move on to others.


The DB

 

[Marconi]

I never realised average could be not so average, or that different software uses different values for what sounds the same but is not,

i have farm land in most directions, i presumed it was about average,
looking at DB's chart that's not average ground or even close.

Bob, I found the ground data strikingly similar between 4Nec2 and Eznec...not withstanding a bit of difference in the descriptive wording.

Do you recall me talking about this ground issue regarding modeling and my having concerns and primarily discussing possible abuse with its use?

 

[Copycat32]

Had an Oeig Antenna specialist starduster up 60 feet on my garage for almost 50 years.. Never had a problem ..
As far as outing a balum uounwould have to put one in line where the coax leaves the mast as the coax outs to the base of the antena .inside the mast.. The antenna is basically a rigig vertical dipole with 3 ground radials.. No coils. . It's a 1/4 wave rediator over a 1/4wave ground plane = 1/2 wave antenna .. It has always worked great for me.. Nice part you can replace the radials with 102 inch fiberglass whips. And it's still works great..