Is the Solarcon Max2000 5/8th di-pole like ?

[RadioDaze2.0]

I started to wonder if this capacitive coupling etc. makes the IMAX2000 more like a dipole...it says there is a capacitive coupling in the centre section.

http://www.k3dav.com/solarconimax2000antenna.htm

An antenna which can truly call itself a 5/8 wave for the 11M band (not many are really the correct length physically) But is it a ground plane type or more like a dipole? (I guess ground plane type is closer given the possibility of after market ground plane kit) but it is an intriguing design that steps away from typical 5/8 straight wire and coil design.

Anyone have any further insight to how this works with its capacitive coupling section and brass tube arrangements that induce RF to the centre copper radiating element. All sounds quite unique.

 

[Road Squawker]

well, I read some of the articles written by your linked person.

most of what he says is basically correct, but,..... certain of his antenna "facts" are flat out wrong.

 

[Marconi]

I started to wonder if this capacitive coupling etc. makes the IMAX2000 more like a dipole...it says there is a capacitive coupling in the centre section.

http://www.k3dav.com/solarconimax2000antenna.htm

RD, I can't make a technical argument here, but I understand the slug (noted as a capicator-coupler) on the center section of radiating wire for the Imax2K...is simply a damper to keep the wire from moving about inside the FG randome (not misspelled).

I have see some I2K's with a damper in the bottom section also. The top section has the wire fully embedded in the FB and is not a randome.

Anyone have any further insight to how this works with its capacitive coupling section and brass tube arrangements that induce RF to the centre copper radiating element. All sounds quite unique.

The only capacitor in the Imax that I know of is noted between the the coil setup and the radiator wire noted in the diagram. It is a short <> 2" brass tube (noted in orange in the diagram) with nylon isolation plugs in each end securing both wire ends of the coil and radiator. Inside this tube is where the induction process happens across a small air gap between the wires.

If I'm wrong on any of this...then I learned something new today...and that makes for a good day.

 

[bob85]

The article is riddled with errors,

 

[RadioDaze2.0]

Thanks for responses. Yes I am aware there is problems with quite a lot that is written, I drew focus away from pulling the article apart. However it does have reasonable diagrams and a few decent photos which certainly goes further than many posts about the antenna.

Ok so the middle section capacitor is not a capacitor at all just something to wedge the copper wire in place. Well it still rattles a lot !

Here we have another picture of the internals:

If this was a straight short either side of the nylon piece (copper wire to copper wire) why would you put this bit of brass tube round it if it was doing nothing ? I am interested in what the circuit of this antenna is when I see such images.

I find it all rather mysterious to say the least.

 

[Marconi]

If that is in the middle section of the Imax then it sure looks like a circuit or a component. The ones that I've see in broken antennas looked like a plastic or rubberized spacer and it fit very close in size to the FG, so I just figured it was a damper.

I have seen other broken Imax antennas that did not have this part.

The schematic drawing of the Imax below does not show this part located on the radiator, but the source is not from Solarcon either.

I'm not sure, but when I did a continuity test on this antenna it did not indicate a capacitor between the ends of the middle section, but the test does show there is a capacitor in the bottom section.

 

[bob85]

I can't recall ever doing a continuity test on the imax upper sections Eddie but i have no reason to doubt you,

The guy is hilarious,
http://www.k3dav.com/rfchokecoil.htm

 

[The DB]

I can't recall ever doing a continuity test on the imax upper sections Eddie but i have no reason to doubt you,

The guy is hilarious,
http://www.k3dav.com/rfchokecoil.htm

I do not remember seeing anything from that guy before this thread, but what he says on that page is nuts. He honestly thinks some random coil of wires will work as well as a coil designed based on actual RF theory? Wow. He clearly knows far less than he thinks he does...


The DB

EDIT, I just finished reading that linked page (the one bob85 linked) and wow, just wow. So according to him, SWR is the cause of the problem that a choke fixes? Seriously? He really needs to do some serious research as the truth is well known, and the information on what is actually happening is out there and not really hard to find... Either that or he needs to find an elmer that will set him straight.

 

[Marconi]

Bob you and DB, are going to really get down on me hard for recounting the following experience I once had with just such a choke as David describes.

The story goes back to when Bob got his original AstroPlane, and I was telling him I had my New Top One up and it was acting bad with RFI here, and I still have it up and working.

At the time I had my feed line outside and flat on the ground, and in the past I swore that doing this before seemed to help mitigate my TVI problems. Well in this case I reported to Bob terrible TVI, and asked him to test for the TVI when he installed his NO A/P. That was in the fall and he said he had to wait until spring before he could get around to doing such testing with the A/P.

Well one day a while back my daughter was going to cut my back yard, so I picked up my feed line and wrapped the excess into a random loop, put a rope around it, and tied it to my antenna P/U pole as shown in the image below.

Later I discovered my TVI was gone and the coax coil in the image below looks very similar to what David shows on your link. Before I did the choke I could not key up but 25 watts now I can do 100 watts with no effects in the station.

 

[Robb]

Is a I2k dipole like?
Don't believe so.

An end fed dipole; isn't that a contradiction in terms? No, as the Sirio GainMaster uses that idea.

I see the I2k as an end fed 1/2 wave with an impedance matching section at the base. It uses that capacitor in the top section coupling RF within the range of the chosen cap value - given.

Why did they put it there? Perhaps to make it more broadbanded? If the freq it is being fed changes (10m to 11 or 12m); wouldn't that change the conductivity of the upper section through that capacitor? And if so, then doesn't that affect they way it radiates and accommodates the impedance? IOW, the overall antenna reactance can change when the freq changes?

Just thinking out loud, so excuse me.
That is all I can see.

 

[bob85]

No I'm not Eddie, plenty of people can relate similar experiences,

You got lucky, moved the coax and/or had just enough in the scramble wound mess to work for you,
I have made them incorrectly too, not scramble wound but not following charts in the arrl or other sources for maximum impedance and they worked to solve issues,

you can be unlucky making coax chokes the correct way and end up making rfi issues worse,

The guy who posted the article has plenty more to say that proves he has no idea how coax, chokes, vswr, antennas work.

 

[The DB]

Bob you and DB, are going to really get down on me hard for recounting the following experience I once had with just such a choke as David describes.

The story goes back to when you got your original AstroPlane, and I was telling you I had my New Top One up and it was acting bad with RFI here, and I still have it up and working.

At the time I had my feed line outside and flat on the ground, and in the past I swore that doing this before seemed to help mitigate my TVI problems. Well in this case I reported to you terrible TVI, and asked you to test for that when you installed your NO A/P. That was in the fall and you said you had to wait until spring before you could get around to doing such testing with the A/P.

Well one day a while back my daughter was going to cut my back yard, so I picked up my feed line and wrapped the excess into a random loop, put a rope around it, and tied it to my antenna P/U pole as shown in the image below.

Later I discovered my TVI was gone and the coax coil in the image below looks very similar to what David shows on your link. Before I did the choke I could not key up but 25 watts now I can do 100 watts with no effects in the station.

A choke like that works based on several factors, such as how big the coils are, how many coils you have, how far away from adjacent coils each coil is. With this type of device, its not just the inductance (how many coils and their size), but that in conjunction with the capacitance between said coils creates a parallel resonant circuit, which has a very high impedance near its resonant frequency. If your randomly created coil of wire has a resonant frequency that is far enough away from the frequency you are using then its help will be minimal. If the coil of wires is randomly created how do you know that you are even close enough to a frequency that will be effective.

Long story short, if such a coil worked for you then you got lucky. Can you honestly tell me with certainty that using some other random length of coiled coax would be just as effective?

Also, did you read what he said later on that page? Much of what he said on that page, and other pages of his, are simply not true. For example, my previous post where I comment on his statement that SWR is the cause of common mode currents. No part of SWR travels on the outside of coax as he claims. Also, as I described above, it is not the electromagnet field around the coil of wires that prevent currents from flowing, its the high impedance of a parallel resonant circuit.

Eddie, did you ever put more than 100 watts through that random coil of yours? Can you honestly say it would have been just as effective at 1000 or 10000 watts? A properly made choke will be effective no matter the power level. If you follow certain basic and easy to follow instructions you can easily build a choke that you know for sure will work for the frequency you are using.

All this being said, I still prefer to use ferrites for chokes... They don't cost any more than the additional length of coax used to coil the antenna, and in some ways are more effective...


The DB

 

[The DB]

Is a I2k dipole like?
Don't believe so.

You believe correctly.

An end fed dipole; isn't that a contradiction in terms? No, as the Sirio GainMaster uses that idea.

The correct term for an Imax would be monopole, unless you have no choke or other addition designed to control common mode currents, then it will try and function as a dipole.

I see the I2k as an end fed 1/2 wave with an impedance matching section at the base. It uses that capacitor in the top section coupling RF within the range of the chosen cap value - given.

It is an end fed 5/8 wavelength. Such a person as the one who wrote the pages linked to above would call it a .64 wavelength antenna, and then waste your time trying to explain the so called big secret of the .64 antenna, he has a whole web page devoted to talking about the .64 secret after all... I'll link said page here. I guess he thinks there is some big difference in going from 5/8 (or .625) wavelength to .64 wavelength... Just another misunderstanding on his part.

Why did they put it there? Perhaps to make it more broadbanded? If the freq it is being fed changes (10m to 11 or 12m); wouldn't that change the conductivity of the upper section through that capacitor? And if so, then doesn't that affect they way it radiates and accommodates the impedance? IOW, the overall antenna reactance can change when the freq changes?

I wouldn't just assume that that is a capacitor. The gainmaster does have a capacitor that is part of its tuning system, but the Imax design wouldn't need such a capacitor along the vertical element to tune. Also, the Imax is a well known antenna, if they had an actual capacitor at that point, people would have known about it before this guy who is making that claim.

Just thinking out loud, so excuse me.
That is all I can see.

No problem with thinking aloud, other than people like me will pick up and dissect your thoughts.


The DB

 

[gamegetter]

Is there a patent filing for the solarcon i-max 2000? I have not been able to find one searching the web.

 

[Robb]

You believe correctly.



The correct term for an Imax would be monopole, unless you have no choke or other addition designed to control common mode currents, then it will try and function as a dipole.



It is an end fed 5/8 wavelength. Such a person as the one who wrote the pages linked to above would call it a .64 wavelength antenna, and then waste your time trying to explain the so called big secret of the .64 antenna, he has a whole web page devoted to talking about the .64 secret after all... I'll link said page here. I guess he thinks there is some big difference in going from 5/8 (or .625) wavelength to .64 wavelength... Just another misunderstanding on his part.



I wouldn't just assume that that is a capacitor. The gainmaster does have a capacitor that is part of its tuning system, but the Imax design wouldn't need such a capacitor along the vertical element to tune. Also, the Imax is a well known antenna, if they had an actual capacitor at that point, people would have known about it before this guy who is making that claim.



No problem with thinking aloud, other than people like me will pick up and dissect your thoughts.


The DB

I see that I was thinking 5/8; but wrote 1/2. Was thinking that a 1/2 end fed antenna uses that format for matching, like the A99. It was late when I wrote it up (or early, to be honest); my mistake.

Dunno what that part is, that started this thread, so I was trying to be logical and see if it panned out or not. Thanks for those comments.

If he wants to know what that part is, I would suggest throwing a meter on it, and then see if it has more capacitance than it should if it were a straight conductor. Dunno how much the radome will affect capacitance however. If that fails to produce results, then I would try using the coil function on a DVM and see it reacts more than it should as well . . .