Any Astro Plane Fans ?

[bob85]

thanks eddie,
avanti say the mast should be 1-1/4" to 1-3/4",
i chose 1-1/2, i don't know which diameter will give the best impedance match,

i remember your FS model with 5 degree downtilt,

what are the blue dots halfway up the lower 1/4wave in the BIG-MAC model?

 

[Marconi]

thanks eddie,
avanti say the mast should be 1-1/4" to 1-3/4",
i chose 1-1/2, i don't know which diameter will give the best impedance match,

i remember your FS model with 5 degree downtilt,

what are the blue dots halfway up the lower 1/4wave in the BIG-MAC model?

Bob, 1.5" inch mast shows the best match, and again the guys at Avanti were right. I tested the idea on my real antenna and it does change the antenna, but again not much net difference.

My New Top One forces me to set the antenna off to one side of the mast and use gate brackets to secure. I've think this too adds to the asymmetry and that is not good.

The Eznec blue dots are all over that Big Mack model Bob, because there are many wires that are all supposed to be connected. The dots indicate wire connections, and if we don't see them where two wires that are very close togehter...we have an open connection. This is easy to happen, and it may not be what is intended.

There is also an Eznec feature that shows us all "open ends." These are noted as a small image like a line or a triangle at those points. That can be helpful during the process of modifying a complicated and very small series of wires like in the hoops we see.

So Bob, when you start modeling in Eznec, you will note it only allows for wires to be straight. We are forced to use lots of smaller wire connections to make a hoop, a loop, a coil, a helix, a bend, or a bow.

When are you going to get to this A/P project?

How much American did you pay, plus shipping? I'm trying to make a deal for 10 of these old antennas, and sometimes I can't understand Henry, the way he talks. The Website is in Dutch or German and I'm limited to one word in German, "Arschloch."

Story: as a small child that is what I called one of my 1st cousins, whom I did not like. The older folks would always laugh. I'm a little ashamed, because my mother spoke fluent German, and the word was not nice...but I understand better today...back then the Big War started and was raging in the World.

The end.

 

[bob85]

my 1-1/2" will do the trick then eddie,

it looked like you had sources in the radials surrounding the lower 1/4wave in the BIG-MAC, the currents on the lower 1/4wave look very odd to me,

im not messing with the astroplane in this weather eddie,
hoping to get another astroplane, so i have one to save and one to play with,

i don't know the exchange rate between you and the Netherlands,
they start at 30 euros each plus shipping for signle antennas,

ours cost £21.87 each including shipping due to buying 17 astroplanes plus other antennas and having them all sent to Mark who redistributed them to us,
i drove 58 miles to Marks to pick mine up the day they arrived,

and most important is been antenna enthusiasts, neither Henry or Mark made a penny on helping us.

 

[Marconi]

my 1-1/2" will do the trick then eddie,

I don't know if I posted my testing results on changing the size of the mast or not, but using 1.5" mast shows the best match for the specs used in my model...which I think now are pretty close to your real antenna specs.

it looked like you had sources in the radials surrounding the lower 1/4wave in the BIG-MAC, the currents on the lower 1/4wave look very odd to me,

Bob, I built that thing based on the sparse details you and others have posted. I'm waiting on Henry to decided if he is going to open his BM up...so he can give me the nitty gritty details from somebody that knows and appreciates the details necessary to accurately model that monster.

Since then I don't remember much except that I think the model produces results that might look like what I expected. I don't remember for sure where I put the source, but I would thing the FP should be tapped somewhere on the bottom coil.

im not messing with the astroplane in this weather eddie,
hoping to get another astroplane, so i have one to save and one to play with,

Hoboy, the wait will force me to revisit all this stuff again...after a time I loose my recollections. Maybe I can get mine and do something, but I won't be posting my results. I will talk about what I see, but I won't be showing anything again. Just talk from now on...that's the only way in this business.

i don't know the exchange rate between you and the Netherlands,
they start at 30 euros each plus shipping for signle antennas,

I can handle that if the shipping for 10 does not blow my mind.

ours cost £21.87 each including shipping due to buying 17 astroplanes plus other antennas and having them all sent to Mark who redistributed them to us,
i drove 58 miles to Marks to pick mine up the day they arrived,

That sounds good.

and most important is been antenna enthusiasts, neither Henry or Mark made a penny on helping us.

I think that is what they wanted to do, and that is great for interested parties.

Check out the model results below. I just finished fixing the antenna again.

I may have posted about the fix already, but I found my two radials were not set at the same angel and the hoop was also off a bit too...as a result. That improved the models gain.

Of course the model, without isolation did have some RF on the FL. The model improved when I isolated it showing little current on the mast. However, when I added a feed line the antenna went to heck in a hand basket as one would expect.

Knowing we will need a choke, I added a choke after much trouble...and finally the model with isolation, a feed line, an a working choke, at the point of isolation, shows little to no currents and just a bit of loss in gain.

 

[Marconi]

Bob, here is the AstroPlane mast size report I did.

 

[bob85]

eddie,

when i put the astroplane up , all im doing is comparing it against the i-10k at the same tip height like i did with the imax & gainmaster,

its not as simple as swapping from one antenna to another like the other antennas if im going to isolate 1/4wave below the hoop,

its winter here, cold wet and windy, hardly the weather you would choose for playing with antennas,
don't get me started on the s-5 of hash im getting from neighbors Christmas lights all over HF,

1/4wave below the hoop is convenient because it also puts the tips at equal height when mounted on the same mast as the 10k and simplifies the isolator,

your last model shows the astroplane to be sensitive to mast & coax length, hopefully isolating will cure than issue.

 

[Marconi]

eddie,

when i put the astroplane up , all im doing is comparing it against the i-10k at the same tip height like i did with the imax & gainmaster,

its not as simple as swapping from one antenna to another like the other antennas if im going to isolate 1/4wave below the hoop,

its winter here, cold wet and windy, hardly the weather you would choose for playing with antennas,
don't get me started on the s-5 of hash im getting from neighbors Christmas lights all over HF,

1/4wave below the hoop is convenient because it also puts the tips at equal height when mounted on the same mast as the 10k and simplifies the isolator,

your last model shows the astroplane to be sensitive to mast & coax length, hopefully isolating will cure than issue.

How did your Imax compare to the I-10K? If you posted the results...I must have missed it or I just forgot.

I think all antennas are more or less sensitive to mast and coax length. I think that might be partly why W8JI and Cebik have warned us about not including the mast and feed line in our models. At least the model is looking like what one might expect in this case and it didn't trash the model.

I set the feed line length to "Actual" and I think Eznec figures the length between the Earth ground and all of the wires used to route the feed line from the ground to the feed point.When I entered a length for the feed line, the antenna did change some, and sometimes the currents popped back up on the mast...but they were never as strong as without the choke.

You are right though,..this model is very sensitive to the length of coax setting. I don't know how you knew that just looking at the images, unless you are sneaking a peak at EzBob.

Working with the choke feature is all new for me, and I likely have something wrong, but it is doing what I think a choke should do, and it didn't crash the model. I had to use 4 wires to route the feed line to the feed point, and that confused me at first...and that was only after many iterations that I figured that much of the feature out.

BTW, this model is isolated at the point where the choke is placed...if you look close.

 

[jazzsinger]

You would need to be crazy to play about with base antennas in uk winter. The further north you go the worse it gets. It's as windy as hell here on the Clydeside. Sadly its the exact opposite of hot as hell. Fecking baltic here now. Only going to get worse as thats the bad weather just starting. Be March or April before its safe to mess about on roofs or masts.

Wish I was in Texas just now. You've no idea how lucky you are Eddie. Lol.
Jazz 73

 

[bob85]

an astroplane been sensitive to mast/feedline length seems like common sense to me eddie, i don't see it as been anything like the sirio top-one or starduster,
it reminds me more of a j-pole on a 1/4wave mast turned upside down,

your models seem to agree,

i am aware that a choke will not always give a high common mode choking impedance, with certain unlucky lengths of coax a choke can make cmc worse,
saying that i have had good results on several different antennas using chokes to reduce or eliminate troublesome cmc.

 

[HomerBB]

@Marconi The third model with the choke and isolation affirms my confidence in the little AP. The gain as shown in the model is nothing to sniff at for an omni vertical. It is as good in the real world here at my place as anything I've run in half wave or 5/8 wave antennas. Better than some.
Seems to walk all over my vertical sleeved dipole made with the coax running up through the lower tube, which is what I have up now.

 

[Marconi]

@Marconi The third model with the choke and isolation affirms my confidence in the little AP. The gain as shown in the model is nothing to sniff at for an omni vertical. It is as good in the real world here at my place as anything I've run in half wave or 5/8 wave antennas. Better than some.
Seems to walk all over my vertical sleeved dipole made with the coax running up through the lower tube, which is what I have up now.

Homer, I recall you gave this antenna high marks after you got your original. I was happy, because I had been talking high praises for this little old ugly looking antenna for a long time, and nobody ever commented, good or bad. Apparently, too few bought the New Top One that Sirio came out with a few years ago, because it has already been removed from production.

If folks said anything at all about the A/P, they told us, without exception, that this antenna only works good when mounted low to the ground. I suspected then...that is where they were going wrong and I didn't see how that could work out to be true with any CB vertical antenna. A 1/2 wave loves to be up high. The FCC was trying to limit our range, and that is why the put the height limit in there...so common sense told me this story sounded like a fist story.

I don't like the CMC effects this design looks to produce either, but back in the days before high tech electronics where all around us, this antenna worked without any notice in that regard as far as I know. The only ones that to this day are all bent out of shape over CMC are antenna tech types. I know they have a point, but sometimes ignorance is bliss, and now days if you live out in the country...you will likely never make a CMC's type problem while you are broadcasting to the world or to your buddies down the road a ways.

If Bob's isolation ideas are successful, and my model seems to suggest they will be, and the process also looks to improve the performance a bit, what does the tell us?

You and I say the antenna works exceptionally well, but will a good fix for the potential TVI problems for this antenna help make it works better, or is TVI and CMC blasting out of this design beneficial.

I hate to hear the weather is so bad over there in England, and well have to wait until Spring to find out what Bob's ideas will show. I will have forgotten all about this by then.

I'm about to post another model of Bob's A/P, as I call it. This has been a work in progress for me. Twice now I have made small adjustment to the dimensions on this model. In the beginning I was using dimensions for the Old Top One I have, but now I think I have some good dimensions...so I've tried to fix that.

Check out how broad and nice the low angle wave front (maybe it is called the beam) this antenna produces. If there is anything that makes the 1/2 wave work good, I would consider maybe this feature alone needs to be considered at least. I did not plan this beam improvement to happen, but I have seen this sort of unique antenna pattern develop for the most part with this A/P, Old Top One, and the New Top One models.

Thanks for your reply Homer, it might just be me and you on this one.

 

[Marconi]

an astroplane been sensitive to mast/feedline length seems like common sense to me eddie, i don't see it as been anything like the sirio top-one or starduster,
it reminds me more of a j-pole on a 1/4wave mast turned upside down,

Years ago before I started modifying my StarDuster with the bazooka balun idea I use and generally solves my TVI problems with my SD'r, I complained about the antenna being reactive to the height it was mounted. Back then I did not understand much. Me and my other SD buddy use to talk about our SDr's, and this was one of the topics, but for us it was always about some special height as I recall. We didn't even know then that the feed line length was probably playing a role and that the antenna was a bit reactive. I did not see the problem much because I did not run any power, but my buddy ran about 200 watts and he really had problems...even with his antenna at 72' feet high. So Bob, I too have experienced antennas that seem extra sensitive to the mast and feed line length even if I wasn't sure what was going on.

I see similarities between my two A/P designed antennas, and I've reported the same for some time. I've compared my Old Top One and my New Top One side by side on both individually on the same mast...many times and I hardly ever see any difference unless conditions go bad.

That said however, I have learned a thing or two about the error of my ways from you guys, and maybe I would do things differently today. If I can get my hands on several of those AV101's like you did, I'm determined to retest all three and really concentrate on the differences. I know they all show about 4 mhz bandwidth at the end of my feed line, and they all show an almost flat SWR curve over 2 mhz.,

There is another thing I consider in my thinking about the A/P as it is compared to the New Top One with a gamma match loop. I'm not positive about this, but this is my thinking. Look at column 4 lines 26-29. I have quoted the part here that says the following:

A construction wherein points c and d are electrically coupled, but where the circuitry is otherwise similar, will produce a similar result, i. e., a closed conductive loop may also be used.

Bob, I wonder what they mean by a closed conductive loop here? Could they be suggesting a gamma?

your models seem to agree,

i am aware that a choke will not always give a high common mode choking impedance, with certain unlucky lengths of coax a choke can make cmc worse, saying that i have had good results on several different antennas using chokes to reduce or eliminate troublesome cmc.

Here, agreement is good Bob.

I'm confident of one thing, that if you look for CMC's problems around this particular antenna...you won't be disappointed. Just asking, but Homer reported he had no such problems, and I think he would know. He then tells us about the guy that bought his A/P having much problems on his mobile trailer-house, but this guy might have no understanding of antennas. Are you are sure your A/P will have problems, or do you have plans to test my claim that the A/P has potentially very bad CMC issues, before you modify and install?

 

[HomerBB]

I put the AP at several heights for the time I had it. I mostly ran it around 30' to the loop, 13' above the roof top ridge of my house. I always ran a coaxial choke at 9' below the loop. However, most of my continuous personal experience with the AP came from when I tested its performance against other longer antennas was when I attempted to get it to the same, or nearly same, tip height. The photo below shows the AP at a 54' tip height, about 15' above a 4 element yagi, with a coax choke 9' below the loop on the AP, 5' above the yagi.
Whether the Yagi underneath mattered for additional decoupling of the CMC event for the antenna I don't know. In this setup no other antenna I had tried before or since out shown this AP except the V4k and directional beams.
In the photo below the AP is 46' to the tip. I would push it up another 8' Yagi and all above it for the test run.

 

[Marconi]

Homer I didn't even think about you using a choke on your A/P. Could you give me your choke dimensions, coax, and VF you used.

I will have to do that on my A/P model without isolation, and see if the model still works the same.

Did you also isolate your antenna.

Thanks for letting me know...just using a choke is probably another possibility for Bob too.

Homer, you commented earlier that my model showed an exceptional gain, etc. For some reason I have this model set at 52' feet to the feed point, and that is higher than my other models. I usually model at 9', 18', 32', and 36' feet. So, 52' feet is going to look really good for the models I've made.

I'll have to reset this model to 32' feet...the height I like best.

The reason I like 32' feet is, because I tend to see less CMC on the models...if I add a mast to the model.

And just as a reminder to The DB, we can't see CMC's indicated below an Eznec antenna model...unless we add an extra wire for the current to show-up on the feed line wire.

Bob, just to be clear on Homer using 9' feet below the hoop to place his choke, I used 8.5' feet below the hoop for the isolation point. I'll also have to try that and see if it changes anything...since I think I have the model so nice.

 

[HomerBB]

Homer I didn't even think about you using a choke on your A/P. Could you give me your choke dimensions, coax, and VF you used.

I will have to do that on my A/P model without isolation, and see if the model still works the same.

Did you also isolate your antenna.

Thanks for letting me know...just using a choke is probably another possibility for Bob too.

Homer, you commented earlier that my model showed an exceptional gain, etc. For some reason I have this model set at 52' feet to the feed point, and that is higher than my other models. I usually model at 9', 18', 32', and 36' feet. So, 52' feet is going to look really good for the models I've made.

I'll have to reset this model to 32' feet...the height I like best.

The reason I like 32' feet is, because I tend to see less CMC on the models...if I add a mast to the model.

And just as a reminder to The DB, we can't see CMC's indicated below an Eznec antenna model...unless we add an extra wire for the current to show-up on the feed line wire.

Bob, just to be clear on Homer using 9' feet below the hoop to place his choke, I used 8.5' feet below the hoop for the isolation point. I'll also have to try that and see if it changes anything...since I think I have the model so nice.

the AP in the photo is not isolated from the mast, however the metal mast is isolated from the earth 10' above the ground. The wood part of the mast only
is below that.