Does any one know any thing about a Big Daddy Beam? 5 elements vertical and horizontial. It 's 22feet long and 19 feet high and wide.
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Big Daddy Bean
- Thread starter Glenn Lincoln
- Start date
If you can get one ...you will love it I have had one up for ten years built like a tank .
Mur
Welcome to the forum Glenn. I don't have any experience with this old beam and I don't know anybody that has, but you could do a search on the forum...there are discussions on this antenna,
I modeled the BD as close to specs as I could. I set the model without tapered elements, because Eznec does not deal with taper well, and I did not model the boom, mast, or feed line. I used .625" inch as an average diameter for the elements, and that also will possibly make some difference from the real world setup results...if I didn't figure close enough.
The antenna is larger tubing than modern bean antennas starting a .75" in taper, and the driven element is 106" on each side. This long of driven element looks to me to really have a lowering effect on the resonant frequency...say nothing about the large diameters used.
The boom shows to be only 2" inches and unless it is well reinforced or uses heavy wall in the boom...it might be a bit small for the added weight of the large longer elements. Being near 22' feet long, IMO the boom will bow and need a boom support harness at the very least.You can test of this before installation.
My model shows 11.71 dbi gain at 13* degrees at 36' feet elevation, but the rejection is very poor at 7.38 dbi at 13* degrees and this is at 27.205 mhz using the dimensions noted in the manual. If my model is even close to accurate, it looks like you will have to go down in frequency to 26 mhz in order for the gain and rejection to perform well or tune the antenna higher in resonance.
To get the best performance at resonance for my model I had to lower the frequency to 26.68 mhz, I can't determine bandwidth or curve but the antenna looks to be very narrow banded...which back in those days was considered good. The only problem I see however might be this antenna requires a lot of transformation at the feed point in order to reach a good tune...and that will increase losses and the results noted are inflated, but I don't know how much. So, I can't even guess if the difference noted in gain between these models could be detectable just using your radio, but you might be able to tell if the rejection changes...that is what I watch for when tuning a multi-element beam.
This is not instructions, it might point to some things to watch for in building, tuning, and working your new beam. Note the models below, the only difference is the frequency settings.
Good luck and keep us posted.
I modeled the BD as close to specs as I could. I set the model without tapered elements, because Eznec does not deal with taper well, and I did not model the boom, mast, or feed line. I used .625" inch as an average diameter for the elements, and that also will possibly make some difference from the real world setup results...if I didn't figure close enough.
The antenna is larger tubing than modern bean antennas starting a .75" in taper, and the driven element is 106" on each side. This long of driven element looks to me to really have a lowering effect on the resonant frequency...say nothing about the large diameters used.
The boom shows to be only 2" inches and unless it is well reinforced or uses heavy wall in the boom...it might be a bit small for the added weight of the large longer elements. Being near 22' feet long, IMO the boom will bow and need a boom support harness at the very least.You can test of this before installation.
My model shows 11.71 dbi gain at 13* degrees at 36' feet elevation, but the rejection is very poor at 7.38 dbi at 13* degrees and this is at 27.205 mhz using the dimensions noted in the manual. If my model is even close to accurate, it looks like you will have to go down in frequency to 26 mhz in order for the gain and rejection to perform well or tune the antenna higher in resonance.
To get the best performance at resonance for my model I had to lower the frequency to 26.68 mhz, I can't determine bandwidth or curve but the antenna looks to be very narrow banded...which back in those days was considered good. The only problem I see however might be this antenna requires a lot of transformation at the feed point in order to reach a good tune...and that will increase losses and the results noted are inflated, but I don't know how much. So, I can't even guess if the difference noted in gain between these models could be detectable just using your radio, but you might be able to tell if the rejection changes...that is what I watch for when tuning a multi-element beam.
This is not instructions, it might point to some things to watch for in building, tuning, and working your new beam. Note the models below, the only difference is the frequency settings.
Good luck and keep us posted.
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s
Murdog, if you see anything I said wrong or questionable, please let me know. I would like the feed back for considering my model results for this antenna. I have some old pretty beat up parts from a beam antenna I took down long ago...that looks to have very similar parts, using swagging, bolts, and element saddles like Maco/Wilson use(d). I thought it was maybe an old Radio Shack or and old HyGain or a Wilson, but Wilson slotted and used hose clamps back in those days.
For example, did your antenna appear long and thus work lower than the specs suggested? How did the antenna hold up after 10years?
Did your antenna bow or did you have to support the boom?
Not a thing Marconi, like I said built like a tank has been through wind storms heavy snow loads with no boom support screws used through out the beam .Yes it could use support but I never have but it comes down every two years for a cleaning and inspection .
I work from 26.285 to the top end of 27 with no problems swr a little high on 26 but flat every where else .
Heavy alum compaired to other beams I have worked with and I climb so I have seen a lot .
Hope this helps out .