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Author Topic: Roof Top Antenna Mounting - DIY Plans ?  (Read 9112 times)
NJ3U
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Posts: 124




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« on: November 29, 2010, 01:36:43 PM »

I'm preparing to mount a Mosley TA33jr on my roof.  Looking into available options including DIY materials.  I'm thinking time spent with a stack of angle, some plate, straps, nuts, bolts, washers and lots of drill bits should yield a sturdy mount ? 

FYI, the antenna is 21 lbs, 4.3 sq ft area and 86 EIA wind load @ 80 mph.

Or send me a pm if you have either of the Glen Martins for sale !

73 and Thnx

Rory
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WB2WIK
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Posts: 20611




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« Reply #1 on: November 29, 2010, 03:00:26 PM »

Unless I was a talented mechanical engineer with a lot of free time, I wouldn't homebrew something like this.

Remember you have to include a way to safely mount a rotator in the structure, as well as support the beam.  Whatever is completed must be lagged through the roof rafters, which requires some careful design and planning.  And if you want to cover the installation with insurance, adequate engineering documentation is typically required, especially if you ever actually need to file a claim: "My roof sustained $10K in damage."  "How did that happen?" Which leads to an investigation and documentation review of what was there.

Using an engineered product that was specifically designed for the application is a great start, and provides acceptable documentation for insurance (and even permit, if one were required) purposes.

I've used the Glen-Martin Engineering roof towers at several sites over a long period of time, and they're a good deal.  They're light but very strong, easy to assemble, and include provision for mounting the rotator inside the roof tower, with a thrust bearing above it, as well as planting the leg mounting brackets over the rafters.  With four legs rather than three, they're stronger than tripods and have the ability to tilt over in either of two directions after they're installed (a tripod can only tilt one way).  They're also strong enough to climb, so in most cases for antenna or rotator servicing, you don't even need to tilt it.

If I were to homebrew something, I'd pretty much copy what they did, exactly.
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AB4ZT
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Posts: 174




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« Reply #2 on: November 29, 2010, 04:29:24 PM »

I second Steve's remarks.  On top of the cost of the materials - your time has value, too.  I bought my GM 9-footer second hand with the thrust bearing for $250 a few years ago - best $ I ever spent - currently holds my TA-33M.  Assembly and installation went much more quickly than I was anticipating.

73,

Richard
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WX7G
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Posts: 6129




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« Reply #3 on: November 30, 2010, 12:04:29 PM »

My only advice is to not get greedy on the tower height if it's not guyed.
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K3JVB
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Posts: 837


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« Reply #4 on: December 03, 2010, 02:48:09 PM »

Ditto...ditto Glen Martin.

Have had an 8 footer up for two years. Not a 70 foot tower....but it does work well at this qth
73
John
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WB2EOD
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Posts: 219




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« Reply #5 on: December 06, 2010, 07:05:14 AM »

Consider a Glen Martin 8 or 9 foot tower and the associated aluminum mast.  I have the 9 foot model.  Installation was a big job.  Careful planning is an absolute must. If you have not already done so, go to the Glen Martin website and download the instruction manual.
   
I looked up ur callsign and you are not very far from me.  Feel free to email me using my callsign at arrl (dot) net.  I may be able to offer some advice.

73 de WB2EOD
     
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K1CJS
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« Reply #6 on: December 06, 2010, 11:39:48 AM »

Agreed with the advice to use a commercial roof mount tower.  Glen Martin is one of the best there is.  Be sure it's attachment points to the roof are solid and tight, and you won't have any problems with it.
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KD0UN
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Posts: 58




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« Reply #7 on: December 18, 2010, 11:56:12 AM »

I used a homemade rooftop for years.  Confident it wasn't going to come down in wind or ice.  This was about eight feet high made of steel square tubing.  Angle iron would likely work fine.  Biggest problem is not safety but roof leaks.  If you hAve a steep roof on a two story house, though, I'm beginning to get cold feet.   Otherwise it's a pretty simple project.  Price the steel, though first.
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K6VOR
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« Reply #8 on: January 02, 2011, 12:00:30 AM »

Hello all,

I am planning on the same type of install. 
Glennmartin RT-832 with aluminum 106" mast and associated thrust bearing.  Yaesu 450 rotor to hold and turn a TA-33-JR.

My question is how to deal with a tile roof in mounting the tower?  I have a couple ideas but more would help.
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WB2WIK
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« Reply #9 on: January 02, 2011, 05:58:39 PM »

Hello all,

I am planning on the same type of install. 
Glennmartin RT-832 with aluminum 106" mast and associated thrust bearing.  Yaesu 450 rotor to hold and turn a TA-33-JR.

My question is how to deal with a tile roof in mounting the tower?  I have a couple ideas but more would help.

It might depend on the type of tile, but I had a G-M roof tower on the roof of my home which had what was called "lightweight cement" tiles.  They were colored gray to match the house motif and were pretty heavy (about 8 lbs per shingle tile) but were called "lightweight" for whatever reason. Cheesy

Anyway, I just used a masonry bit to drill right through them.  No problem at all, it went right through without much effort at all.  A bigger challenge was walking all over the roof without cracking any tiles, because a step in the wrong place and they will crack!
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KI4SDY
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Posts: 1452




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« Reply #10 on: January 02, 2011, 07:35:07 PM »

WB2WIK's response is exactly correct! You need to read it over several times before you do something that may damage your roof, void your roof warranty and cancel your insurance! Shocked In addition to that, it will be an ugly eyesore for your ham hating neighbors. I hope your going to get a permit, because they are probably going to call the local government to see if you got one. Angry

Get yourself a heavy duty push up pole and attach it at the peak of the house. Guy it well and you can do the same thing safely and for less money. Grin
« Last Edit: January 03, 2011, 07:57:37 AM by Guy "Vern" Wells » Logged
K1CJS
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Posts: 6042




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« Reply #11 on: January 03, 2011, 10:30:29 AM »

I used a homemade rooftop for years.  Confident it wasn't going to come down in wind or ice.  This was about eight feet high made of steel square tubing.  Angle iron would likely work fine.  Biggest problem is not safety but roof leaks.  If you hAve a steep roof on a two story house, though, I'm beginning to get cold feet.   Otherwise it's a pretty simple project.  Price the steel, though first.

Roof leaks are always a problem, but they can be minimized.  First, pre locate your tower so you know EXACTLY where you have to drill holes.  Second, use machine bolts and nuts, not lag bolts.  Yes, I know that means long bolts, but it WILL be worth the extra cost.  Lag bolts WILL work loose in time while machine bolts held by nuts will not.  Third, the hole size--use a drill bit that will just allow enough room for the bolt--no bigger.  Fourth, get a can of roofing tar and carefully apply it to the area where the leg will be bolted to the roof after you drill the hole and just before you put the bolt in.  Coat the end of the bolt near the head with it too.  Put the bolt in and tighten up the nut, taking care not to overtighten it.  Tighten it just enough to prevent movement.  On the underside, use a fender washer and a lockwasher under the nut.

Also, as with everything, you will have to maintain it.  Inspect the tower installation every spring and when you do any antenna maintenance.  You may have to re-tighten the bolts every once and a while--but only if they've loosened, that will be done from the inside of the attic/house.  An extra coating of roofing tar on the head of the bolts and the area of the leg end on the roof every couple of years won't hurt, either.  If you really want to be thorough, a dab of tar on the nut/bolt on the inside to stop the nut from loosening may give you further peace of mind.  
« Last Edit: January 03, 2011, 10:32:42 AM by Chris J. Smith » Logged
NJ3U
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Posts: 124




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« Reply #12 on: May 09, 2011, 06:30:06 AM »

Update_ May 2011.

After reviewing all my options and many many opinions from a multitude of Hams, I've made my decision.

I bought the T6061 Alum from Fozios in New Castle Delaware at a fraction of the cost of any other jobbers available, they cut the pieces into job specific lengths.  Cost of metal for the tower, lighting rod and 9 foot of 1.5 od .125 wall mast was 175$.

A buddy of mine did the miter cuts for the top bracket and lower supports. ( Thanks Mike ! )

Bolts where stainless from DX Engineering and each got a dab of NeverSeize !

A built a jig to maintain square and center and used vise grips to hold it all in place while drilling with handheld drills.

So after approx 12 hours of work, the tower is complete and ready for final alignment and tightening.

Check out the project and progress on my PhotoBucket web page entry found on my QRZ entry.

I'll update this post as the project continues.

73 Kc2UML Rory
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K3GM
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Posts: 1815




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« Reply #13 on: May 09, 2011, 07:34:57 AM »

Nice job!  By the way, I never got back to you with the Kanji translation.  They turn out to be very simple instructions like, "If you hear a grinding noise, stop using the the bearing right away and examine"  All of the panels are like this, simple intuitive instructions.
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