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I am surprised it has not been asked already but just what kind of antenna is the 40 foot long beam anyway? What band(s) does it cover? My concern is not so much with the mast and vertical (well a little bit) but rather with the ability of the Glen Martin roof tower to support such a large antenna regardless of how well the roof is reinforced.Roof mounted antennas are subjected to a lot of weird wind forces that result from uplifts caused bu the angle of the roof and this places odd bending moments on such a large antenna. Again, what is the model of the antenna?

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Front/back ratio comes from the antenna. Forward gain comes from the wall socket.

I think you've already gotten some very good advice, talk to 'Glen Martin' about what you propose to do. It would only be a guess, but I think I can tell you what you will be advised to do/not do. I also think you can guess what that 'guess' would be, right?
- 'Doc


Completely beside the point...
The only antenna with a 40 foot boom that I've -any- experience with definitely was not for 11 meters. It was also not something the average person would ever have to worry about putting up. Oh, I'd love to have one! But not after seeing the 'mechanics' of the thing. It was built to 'government specifications' sort of, and considering the weather where it was erected, that's a very good idea!

I'm kinda curious myself, since my tennadydyne has a 24ft. boom and 38ft. ele. and as far as that vertical he would be better off with something less gimicky like a 10K or even a V58 with one of those you wouldn't need that much mast. I would, if you already have the mast, go ahead and mount the vertical on it and find a way to get it upright on a calm day and see how much it sways while it's on the ground

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If you run, you'll only die tired.
CDX-251,2SF251,AE926,

I have rethought this idea, and decided that the 40' boom isn't practical for the area I am trying to install. Now I am thinking of going with a Signal Engineering Lightning 4+ Quad antenna (real close to an 18' boom), with a ham IV rotor inside the Glen Martin RT-936 rooftop tower. I have a med duty Rohn BX series tower that is 40' tall-- Im just going to mount the merlin omni antenna up on top, on the other side of the yard-- far enough away so that the Quad wont come in contact with it when it turns.

Charlie

you keep arguing with logic and reason and disagreeing with the guys who have done this before and can tell you ti wont work yet you STILL argue the point. If you know what you are doing and are sure that 24 ft of 1/2" thick pipe will work then by all means do it. Please be sure to scan the copy of the home owners insurance claim before you submit it when it falls off the roof and kills the neighbors kid.

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Bomb Diggity!
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Quote Bob85: "peoples' personal non factual opinions mean nothing to me period, BS is 10 cents a gallon anywhere you look for it"

Dont confuse issue with detail:
mount the m-107 0r m-108 that does have the 37.5 and the 40 foot boom
on the tower and the ground plane goes on another tower away from the beam.
and yes there are some flatside beams that are longer than 40 foot
for 11meter or "cb channels"

read read and read and learn and write down and remember.

have a few engineers on hand that think since they read the book from front to back they know it all.
and once you get them on the ground and put a tool in their hand then they have to read the book on how to operate that tool.
quite frankly i wouldnt let them operate my lawnmower.

you can have all the brainsmarts and all the right answers but if you dont have any handson experience you can be one of them that sit on the ground and point the finger and let everyone think that he knows it all.

Someone give that man a White hardhat and a shovel to lean on

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As such the device is not protected against interference and the parties operating such a device can not seek redress from parties operating radio communication services. In other words they do not get protection from interference and thus must accept interference. Because of this, any part 15 device should be designed to operate robustly under all conditions

And just a reminder...just because you have a ham license....actually almost worse now that you do, doesn't give you any exception for 'illegal' CB operation.

People who know better will immediately recognize that vertical for what it is and likely many of the common 'CB' beam designs too.

Just saying, since you are putting up such a monster beam...it will attract a lot of attention.

good advice. Thanks.

I have since decided to scale down, and run a 4 element quad instead.

Much more practical for what I am trying to do.

Charlie

please read my last few posts toward the end. I have realized that the original plan will not work.. I am not going with a 24 foot long mast anymore. a 12 foot or even a 10 foot mast will work well with a 4 element quad. The mast will be nested inside the roof tower about 3 feet (adding in the height of the rotor mounted on the shelf)..

thanks for posting LO...

Charlie

Those Glen Martin 9 foot towers are very solid so you should have good luck with that as long as your installation is solid. I've had my eye on one for a while.

When you cross brace your rafters and put the rod through them, consider a fish plate backer that has a few inches of steel around where the nut on the rod meets the braces.

The big Tenadyne LPDA models were one of a few options I considered and the 936 tower is rated to hold them. A quad should be no problem. They are also on my list for consideration.