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Marconi's Eznec 5 model of the Big Mack

Hello Marconi,

Yes it seems the antenna is rare.
I have done a "active" search. (including placing ads etc.) for a couple years.
Asking around on the "HAM-international" forum etc etc.
All that didnt work.

This one came from a basement from a Radio shop.
The guy retired and "forgot" about it...
He also had a couple hygain bigguns / astroplanes etc.

I collect "old famous" antennas and am quite happy with this Big Mac.
After the pictures its going back in the box and leave it...

One reason why they are rather rare, is the mechanical aspect.
If you have a "slight" breeze..you get worried if it will brake hihi.

Anyway ill read the thread again and try to collect what u need.
Hang on, first a couple other things to do.

Kind regards,

Henry
 

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I look forward to seeing the exact dimensions of this big antenna. Hopefully Henry can send some photos and exact numbers on that.
The idea of duplicating it is intriguing. I believe it can be done with enough integrity to not have to worry about losing it in anything short of a major storm, ie hurricane/tornado.
Whether I can pull it off with my plumber's special materials raises some doubts for me, but I am enjoying the gnawing sensation in my brain for the moment . . .
 
Hello Marconi,

Yes it seems the antenna is rare.
I have done a "active" search. (including placing ads etc.) for a couple years.
Asking around on the "HAM-international" forum etc etc.
All that didnt work.

This one came from a basement from a Radio shop.
The guy retired and "forgot" about it...
He also had a couple hygain bigguns / astroplanes etc.

I collect "old famous" antennas and am quite happy with this Big Mac.
After the pictures its going back in the box and leave it...

One reason why they are rather rare, is the mechanical aspect.
If you have a "slight" breeze..you get worried if it will brake hihi.

Anyway ill read the thread again and try to collect what u need.
Hang on, first a couple other things to do.

Kind regards,

Henry

Thanks Henry.

What I need is every dimensions necessary for a close to accurate model, and for sure the correct dimensions for the two coils and the three tuning wires, (diameter, height, width, spacing, and overall wire length if possible).

The spacings for the hubs around the tuner element areas.

Diameters and exposed lengths for all wires, including the two insulators dimensions.

Maybe you can give me an idea for the offset and the bend in the tuning elements, length and diameter. As an example of these dimensions for the bottom and the top of the tuner, you might suggest something like the following:

the tuner wires offset is 1" from the radiator, and the middle of the tuners are 10" inches offset, and the wires are 108" x .375". And if possible, the space between the two hubs that hold the wires is an important dimension too.

I'm also curious if the bottom of the radiator is adjustable or fixed inside the insulator, or did they design the bottom insulator that way in order to get a foot or so of tubing down there to take much of the stress...instead of a raised insulator, like is at the top.

Henry, you if anybody on these forums, knowing full well how to model, should know what I am asking for and what I need without going back an seeing if I left some specific details. Earlier, I didn't do anything but ask for the dimesions.

Henry, I think we both know that taking down all the dimensions for an antenna is far more difficult that one might imagine. So, if you feel this is too much work to get me the information, then don't worry about it, I'll understand.

At first I thought the Big Mack might be something special, but after I reconsidered that idea and seeing how it models, I don't think this antenna will show anything specials in performance, just like my opinion for my Wolf .64 has changed after modeling it. Of course dimension error can make a difference, but I see similar patterns with both the BM and the Wolf.

The Wolf is a good working antenna, but it is surely not a collinear and comes no where near performing like a collinear. I believe Bob hit it right when he compared his Big Mack to his Vector Hybrid, the Big Mack may have a slight edge in performance, but they both don't fly were well in windy areas.

Earlier I convinced myself that both these antenna designs suggested they possessed the necessary elements to work like a collinear, but I have reconsidered...neither will come close.

I think, at best, they both will probably respond about like Bob experienced with his Big Mack some years ago, and that result was nothing specials.

I don't believe either the Big Mack or the Wolf .64, will ever show true collinear type results...like I see with the Big Hair collinear 5/8 wave model I made recently. IMO, there just isn't enough apparent advantage over a 5/8 wave to be correctly classified as a collinear for any of these three antennas. The Big Hair is the only one that really shows a collinear advantage in gain.

On the other hand I also see some limitations in the pattern with the Big Hair too, the maximum gain lobe is way too narrow to really be effective in 11 meters, where line of sight and sky reflection often work together to produce good performance. So, I'm not sure the 3db gain that a collinear design is supposed to produce...is worth all the hoop la it is given, particularly working 11 meters.

I know you're busy, so do what you think best regarding sharing the Big Mack dimensions, what I requested of you will take a bit of effort and time, and for me to get anything less than complete dimensions would be a waste of my time too, I've already tried plugging in some random numbers and the results are not there.
 
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big mac home brew?

did anyone ever follow up on trying to make a big mac style antenna home
brew? I've been thinking about it, curious if anyone has attempted it...
 
did anyone ever follow up on trying to make a big mac style antenna home
brew? I've been thinking about it, curious if anyone has attempted it...

Henry never followed up with me on the dimensions he promised. I think maybe I've probably deleted the old guesstimate model I did too.

The only thing I think the Eznec model showed...was it is possible to produce some collinear phase effects with a 1/4 wave feeding a 5/8 wave mounted close above.

But, IMO you have to have a "real phasing device" in the antenna in order to see some real collinear results such as my Eznec model looks to indicate above.

Hey Henry, did you ever model the BM? hihi
 
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Hello Marconi,

To be honest, I have spent a lot of time in the Ham Big Mac lately.
With reason:
Frans van der Velde (original Ham-International) has provided the right to reproduce the antenna to us.

You know how enthusiastic I always am about antennas, it actually is difficult for me too express how happy I am regarding the trust we have been given on this matter.

At this moment I’m "upgrading" the entire antenna to present day standards.
Looking at the electrical/mechanical side, but also the "legal" part of the antenna
(Patent etc) of course time is always limited as it still is a "living/hobby" for me not my income. So sadly it will be a slow progress.
But because of the situation I am able to do "better" compared with others, as I’m willing to spend more time and effort in things....I haven’t got a "money goal" to achieve, I only have a reputation to put on the line. So for me the only thing that counts is: providing the best.

Regarding your question.
I'm afraid I won’t provide data (yet)
I have always…always provided data, always explained things, always provided information on how people could do it “ better”, and never told anything that wasn’t true.
Putting it humble: doing that, has provided quite some “interesting” achievements on 11meters.

But it also has a downside:
As there are some manufacturers doing exactly what I do.
Now, this might probably be consider as a compliment, however I can’t escape from the feeling of theft.
In fact it is that bad...there are those who exactly " copy paste" things and sell a couple of dollars below my price.
This being the result of always being help full to others, I think you can understand how I feel about those.

So, I do apologize as I certainly know what I have said. But it is those who take advantage which put me in the spot I am……I’m trying to find my way “ around” them and do hope to provide some help on the Ham Big Mac (and equivalent) as helping others still is the main goal..
I just have to figure out how to deal with those others.

Hope you can understand my point of view in this subject.

Kind regards,

Henry
 
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Henry, I went back and re-read the thread, and you did say you got the BM in hopes of maybe reproducing it at some point...I just missed that part in my first reading.

I understand your decision not to publish the dimensions.

I also went back and found the model I made in my download folder. I opened it up and set the model up in free space to see how the AG looked, and it was terrible, so we can't depend on the results I posted.

No doubt I have the feed point located in the wrong place and/or the coils are very likely not right either.

Can you tell us anything about the antenna performance you see, and compared to what?
 
big mac coils

Marconi, those photos you uploaded last year were perfect. I took your size
estimates and with a little arithmetic worked a inductance value for the tap
on the matching base coil. if the tap is legit in the photo then the ant comes out to 12.7 ohms. the base coil matches it up to 50 ohms for coax feed. not sure I trust what I am seeing but a start. I have put up a horizontal 1/4 wave wire, insulator and then 5/8 wire following it. all up a few feet to experiment with. the 1/4 has a couple horizontal radials. the 1/4 resonates low because of the ground. next to wind a coil for the 5/8 section. a nice 80'
tree to hang this from would be handy but alas.. Henry, good luck with the project. It would be nice to see it in a catalog or even custom order one!
 
But, IMO you have to have a "real phasing device" in the antenna in order to see some real collinear results such as my Eznec model looks to indicate above.

Marconi, phasing devices used in collinear antennas take many forms and not all are 180 degrees. They include shorted phasing stubs, helical coils, LC resonant circuits, single loop and coaxial sleeves just to name a few. All they really have to do is alter the phase the correct amount that will drive the next section in a phase that is constructive with everything before the phase shift. They should do so while radiating as little energy as possible during the phase shift. Understanding how each of these works may make the "others" more real to you.

PS: Henry, I didn't forget about those measurements.
 
Marconi, those photos you uploaded last year were perfect. I took your size
estimates and with a little arithmetic worked a inductance value for the tap
on the matching base coil. if the tap is legit in the photo then the ant comes out to 12.7 ohms. the base coil matches it up to 50 ohms for coax feed. not sure I trust what I am seeing but a start. I have put up a horizontal 1/4 wave wire, insulator and then 5/8 wire following it. all up a few feet to experiment with. the 1/4 has a couple horizontal radials. the 1/4 resonates low because of the ground. next to wind a coil for the 5/8 section. a nice 80'
tree to hang this from would be handy but alas.. Henry, good luck with the project. It would be nice to see it in a catalog or even custom order one!

wa1knx, when I went back and read this thread, I opened the pdf file for the model I had posted and I was reminded that the bottom coil I used was bigger than it should be, maybe twice as big.

My only purpose in trying to model the Big Mac was to see if I could get close and maybe see if such a model would produce collinear type performance at a low angle. I was amazed when the model showed collinear type gain, so I posted the model results.

The thread only lasted a few days and it stopped...so I figured no body was interested in this old antenna and I stopped working on it.
 
coil pics

marconi, it was the pointer you posted to the coil pics in this thread I used. its enough to work the antenna out with..

Bigmack Photos by ukmudduck | Photobucket

..then you added notes to sizes. the antenna could be done. thick wall
aluminum pipe for the bottom 1/4. ive seen delrin rods online. not sure whether that or lexan or fiberglass would be best for a insulating rod
to put a matching coil on. another delrin like insulator for a phasing coil at the top of the 1/4. then a I10k type taper 5/8 above the 1/4. itd be big! 73 dean
 
marconi, it was the pointer you posted to the coil pics in this thread I used. its enough to work the antenna out with..

Bigmack Photos by ukmudduck | Photobucket

..then you added notes to sizes. the antenna could be done. thick wall
aluminum pipe for the bottom 1/4. ive seen delrin rods online. not sure whether that or lexan or fiberglass would be best for a insulating rod
to put a matching coil on. another delrin like insulator for a phasing coil at the top of the 1/4. then a I10k type taper 5/8 above the 1/4. itd be big! 73 dean

wa1knx, I wouldn't want to try and provide anybody with an accurate take-off for all the dimensions for the Big Mack. It would be a lot of work just to get all of the important dimensions right.

I looked at my notes and I found that I used the following atrists image from the BM Manual to get the idea that the matching coil was bigger than it really is...as compared to the photo images of the two coils I used to estimate my dimensions. So much for artist drawings.

Die wohl einzige collinear gestockte CB Antenne,

I'll wait on Henry to get us up to speed on this one if that is possible. There are just too many important dimension to consider, and even then testing of the model in the real world would be necessary to really say for sure.
 
Just a note: I was looking over all the supporting materials and I see that the BM only has three radials instead of 4. My model has 4 radials, and that would make some difference, but IMO it might not be much difference.
 
marconi, it was the pointer you posted to the coil pics in this thread I used. its enough to work the antenna out with..

Bigmack Photos by ukmudduck | Photobucket

..then you added notes to sizes. the antenna could be done. thick wall
aluminum pipe for the bottom 1/4. ive seen delrin rods online. not sure whether that or lexan or fiberglass would be best for a insulating rod
to put a matching coil on. another delrin like insulator for a phasing coil at the top of the 1/4. then a I10k type taper 5/8 above the 1/4. itd be big! 73 dean


wa1knx, the original big-mac base insulator uses a tube in a tube with an insulator between them like a maco v5/8,

if you want to go to a setup like the i-10k i would use fiberglass rod like the 10k but 1.5" rather than 1" diameter,
the big-mac is a lot of antenna to be swinging on a piece of delrin or lexan(y)
 
phase coil insulator

Bob, what do you think the phasing coil insulator was made of. in the photo of the coils it also looks like there were holes in the phasing coil insulator (?) the photos aren't bad. it looks like there was a plastic strap holding the spacing of the turns in place. the instruction manual mentioned the phasing coil came in two pieces and bolted together if I read right. And the swr was touchy in a
breeze I guess. Marconi, your size estimates of the coils look good enough
from the photos of the whole antenna up, and the coil pics. dean
 

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