New Top One dimensions for Homer

[Marconi]

hopefully, it isn't my analyzer on the blink . . .

Homer here is my last Antenna Work Sheet for my New Top One up. You don't see the differences in matching results vary as dramatically as in the meter results you posted. I realize you are recording far less data, but this might also be confusing the results. I don't think these conjugate type match results we tend to see with antennas are totally linear even if the SWR results do appear as linear. Maybe if you recorded your result in much smaller step rates your results would look more typical.

You will also see my bandwidth is about 1/2 as wide as you are noting for some reason too, but that might be something else causing or contributing to that, so in your case you may have to look at some issues in your construction.

Also note how consistent the complex impedance value of Z is for this antenna across the band.



I think you are making your step rate much too large using changes in SWR instead of recording results at much some smaller steps, up and down in frequency.

I think if db's Smith Chart math is close to correct, his results also indicates the same issues are going on in your results. It might not be your meter at all.

Here is a pdf file if you can't read the jpeg.

View attachment New Top One.pdf

 

[HomerBB]

When you make the change with the top hat I would expect the match to be very close if the length is close. Otherwise, I don't see how there could be much of a difference. As best I can recall when I made the change on my Old Top One the first two tries I made the length too short and then too long. I can recall all I had to do was get the length right and I got the resonace right on with the third try however I was using a working feed line.

When I requested your confirmation of my full 1/4 wave length at 27.205 resonance I was not sure what you used for the diameter of tubing in your NTO.

My testing idea for the full 1/4 wave used the old top one with a much smaller radiator diameter, so I don't think we can expect to prove much as a result of comparing.

I don't know how much difference such a diameter difference would make, but under the circumstances I would expect your NTO to be too long if you used the length I found at about 87.5" - 89.5" inches while using .625" average radiator diameter.

We will see what happens when and if I get the analyzer readings cleared up.

#2. I'm not sure, but you might be right about the radial cone being much larger and making the bandwidth wider. Since you got a good SWR with the radials isolated...maybe the mast was serving as the bottom of the dipole instead of the radials if you didn't have your mast isolated.

That seems likely

My New Top One shows a nice wide bandwidth of over 4.4:1 using my analyzer at the radio end of the feed line, and about 5.4:1 with my inline meter, so I think the results I would actually get at the feed point would be somewhat less. Sirio publishes a 2.0 mhz bandwidth range of <1.50:1, so I'm not sure what exactly causes your antenna to show 7.40 mhz for <2.0:1.

Yes, that has been a puzzle to several.

I gave you the gamma dimensions I have, but I can't suggest any solution to your matching issue. I will say that the top of the NTO does have a hub that supports the top hat radials and it is at least 2" or more tall, so the gamma strap does mount a little below the very tip like you found.

The results I got was a eyeball the gamma and see how close. I put it on the analyzer, took a photo of the readings, and closed shop for the day. No fine tuning.

The last few days have been tough for me Homer, so I hope I am making sense in my posting to your comments.

You've done fine. I hope youi have better days ahead.

 

[HomerBB]

Thanks for the graphs and charts everyone.
I will try again as soon as I can. I may have some issues with attenuation, or coupling with another antenna too close, so I'll move the testing location next time and see whether that helps. Construction seems tight, but I'll revisit that, too.
The suggestion of smaller increments of readings will likely get us closer to right. I was in a great hurry and may have moved right past some light shedding data from the analyzer.

 

[Marconi]

Thanks for the graphs and charts everyone.
I will try again as soon as I can. I may have some issues with attenuation, or coupling with another antenna too close, so I'll move the testing location next time and see whether that helps. Construction seems tight, but I'll revisit that, too.
The suggestion of smaller increments of readings will likely get us closer to right. I was in a great hurry and may have moved right past some light shedding data from the analyzer.

Homer, I don't remember if I posted the following idea already, but I remember thinking about some results from my Eznec models for my New Top One that might be of interest to consider.

My models suggest that this antenna may well work just about as well if the gamma is not used, the antenna is isolated at radials/radiator junction like a dipole, and instead using a direct coax pig tail connection like you did with your homemade AstroPlane.

In fact, when I place the feedpoint source for the model near the top of the shortened radiator the antenna needs some matching device. However, if I place the feedpoint at the junction of the radials and the radiator, the model shows a nearly perfect match just about like a dipole. So, if you continue to have matching issues using your gamma...maybe you could try and direct feed your antenna in the middle. I think the model with the gamma shows a little bit better gain advantage...but as I recall is was not much and the patterns looked the same.

 

[HomerBB]

I suspect that is true, however when I do that we will have made a Merlin.

 

[Marconi]

I suspect that is true, however when I do that we will have made a Merlin.

Maybe that is why Sirio tells us their New Top One is a 1/4 wave ground plane, it is just fed at a different point.

Homer I just looked on Sirio's Website and they do not list the New Top One anymore.

 

[HomerBB]

Maybe that is why Sirio tells us their New Top One is a 1/4 wave ground plane, it is just fed at a different point.

Homer I just looked on Sirio's Website and they do not list the New Top One anymore.

I looked for it, too. Same thing, not listed.

 

[Marconi]

I looked for it, too. Same thing, not listed.

The original AstroPlane was fed at the center hub of the antenna also.

I hate to start rumors, but maybe Siro has discontinued the NTO about like they did with the A/P and the Old Top One. Does this suggest that the older models and the NTO were ultimately all total sales failures?

 

[HomerBB]

The original AstroPlane was fed at the center hub of the antenna also.

I hate to start rumors, but maybe Siro has discontinued the NTO about like they did with the A/P and the Old Top One. Does this suggest that the older models and the NTO were ultimately all total sales failures?

No idea, and clearly speculation on anyone's part. I think businesses tend to follow sales the with these type decisions.

 

[M0GVZ]

Part of its problem is how it looks. Its a lot of metal to have in the air and not what many people would view as a conventional antenna.

I don't know if this is of any help but Nevada Radio here in the UK have them in stock for £69.95

http://www.nevadaradio.co.uk/amateur-radio/antennas/base-antennas/sirio-sy-27-4bb

There are several retailers selling them in the UK including Knights CB.

Radiozing is selling them on Ebay and does do international shipping although they don't have the USA listed however it wouldn't harm to ask...

http://www.ebay.co.uk/itm/SIRIO-TOP.../300986092485?_trksid=p2054897.l4275#shpCntId

 

[HomerBB]

I had thought the same thing about all the metal for an antenna of its size. My radials cone is heavier built than either the V4k or the NTO, I suspect, but lifting it into the air was much different than lifting any 1/4GP or the homebrew Merlin I had made.

When the wind is blowing hard being on the roof trying to set it into the mast is not the place to be.

 

[Marconi]

I had thought the same thing about all the metal for an antenna of its size. My radials cone is heavier built than either the V4k or the NTO, I suspect, but lifting it into the air was much different than lifting any 1/4GP or the homebrew Merlin I had made.

When the wind is blowing hard being on the roof trying to set it into the mast is not the place to be.

When I could mount antennas here Homer, I would mount them to the mast and raise up the whole thing and then secure the mast in place. I guess that sounds strange to hear, but that is the way I did it and I never lost an antenna or a mount.

That said, when I mounted the A/P, and NTO, about like the Starduster, I could easily see that trying to do that job high up above the ground would not be nearly as easy as one might imagine...with all that stuff hanging down right in the way. Woe-is-me if I had to tune, tighten, or change some dimension.

You be careful Homer.

I did what I did above just to make it easy for me or so I thought. Today such a thought scares me.

 

[HomerBB]

That's what I do when I'm working/tuning from the ground with a temporary mast, but when I'm trying to get it on the permanent mast I n the house it's another story.

 

[hotrod]

The original AstroPlane was fed at the center hub of the antenna also.

I hate to start rumors, but maybe Siro has discontinued the NTO about like they did with the A/P and the Old Top One. Does this suggest that the older models and the NTO were ultimately all total sales failures?

last time ilooked copper, dnj ,h&y had them.

 

[Marconi]

last time ilooked copper, dnj ,h&y had them.

I agree hotrod these distributors may still be selling these from inventory, but I don't see the New Top One listed in Sirio's product list. So it may be gone if Sirio does not replentish the distributors.

That was my only point, plus I remember how the old Top One that Copper's sold for years stopped beign sold suddenly and without notice it was gone.

http://www.sirioantenne.it/antennecat.php?idc=1008171241&idg=1008171169