Many people live in a HOA, densely populated area, or just don’t have any room for guying. This will definitely limit how high you can reach and what (antenna, flag, etc.) you can elevate. This post will go into detail on how I was able to erect a 7-8 foot vertical antenna (with LMR-400 coax as the feed line) on the chimney of my house. After enduring more than a year, making it through our brush, and surviving the remnants of a hurricane with 70-80 mph winds; I am ready to show you how I did it. Let’s dive in.
What can I put on top of it?
Now before we go any further, I want to crush your hopes and dreams of putting a large TV antenna, a satellite dish, a beam antenna, or anything that has a bigger wind profile than what I used. The 7-8 foot vertical antenna added height to the structure and weight all of which add stress to the mounts used. Fiberglass masts are strong, light, and able to resist bending, but even they have their breaking point. A guyed structure you can erect and almost forget about – but an un-guyed one, is a totally different beast and other considerations are required.
What fiberglass Mast did I use?
I used the Max-Gain Systems 50 foot MK-8-HD BLACK Stealth Mast. I DID NOT USE THE ENTIRE 50 FEET. I wanted to get that out of the way quickly before you think you can use that mast completely un-guyed at its maximum height. If you wanted to use the entire 50 feet you would need to use guy lines in order to stabilize the mast. What I did was only extend each section 46 inches. Each tube of the MK-8-HD mast was 93 inches long plus the telescoping clamp (you cannot figure the clamp in any measurement as it only supports the vertical load). Only extending each section 46 inches allows for additional “overlap” at each joint going down the mast increasing rigidity. See the diagram below:
Not to go off on a rant about safety, but roof safety is one thing that you cannot skimp out on. Be sure, if you can, to use proper climbing equipment where possible and DO NOT GO FAST, TAKE YOUR TIME and think out your every movement while on the ground BEFORE you even go up the ladder. One of the best rules of thumb is to always remember to have three points of contact even on a roof. If the shingles are hot, wear gloves. If you have a slick roof, algae on your roof, or debris on your roof please reconsider getting up there at all.
What Mount did I use?
I used a new mounting system that consists of two brackets that I installed on the roof side of my chimney. The Mast Wall Mount Bracket is sold in two sizes, but selecting the “HD” option, that I needed for my mast, I was able to use the larger mount. I used two kits, a total of 4 mount brackets, as I wanted as many attachment points as possible up and down the bottom mast section. I was able to fit 3 of the brackets on the side of the chimney for the mast to attach into – one each towards the top, middle and bottom. That LONG mast, even with just a vertical antenna on the top (super small wind profile), will exert massive forces on those brackets. The longer the lever arm, the greater the force. The three brackets will distribute this load very well. I first went inside the attic where I had access to the inside of my chimney and see exactly where the framing boards were. I did some measuring to determine exactly where I was going to drill into because once you get on the roof you need to know exactly what you need to do so you can always focus on your safety.
When I had that determined, I went on the roof with my mounts and all of the tools I was going to need in my tool bucket that had a sling on it. I put that around myself which allowed me to have both hands free to focus on staying steady on the roof.
Here is a list of tools that I used during the mounting process:
- Tape Measure
- Drill with drill bit pack
- Ratchet with already preselected sockets (I checked fit while on the ground)
- Small one foot long Level
- Plumb bob with string (a device you can tie on something and it will hang down to show true vertical)
When I got over to the chimney I grabbed the bracket and drilled the first hole for it to be mounted. I then used a lag bolt and ratcheted it to almost tight, but still loose. I then grabbed the level the leveled out the other attachment point. Drilled the hole and tightened up both bolts. The top mounting bracket was now set. I then proceeded to grab my plumb bob and tie it to the top mount at the point just forward of the two bolts that hold all of the pieces together (YELLOW). I then reached for the bottom bracket that has a third leg on it. When I put it on the wall to mount it I noticed my plumb bob was in front of the bottom mount and not lining up. There was a trim piece on the outside of the chimney that I did not account for (ORANGE). So I had to measure the depth of the trim piece then climb off the roof, find the correct pressure treated lumber piece to use, cut it to the lengths I needed then climb back up to continue.
I reached for the bottom bracket again with my additional mounting board I had just cut and proceeded to line it up perfectly with my plumb bob. When I had it all set I used my drill and ratchet to set one of the top two mounting holes for the bracket. I used my level to make sure the bracket was level and my checked my plumb bob to ensure I was directly below it. I then proceeded to drill and ratchet in my other two lag bolts. Be sure to understand why I don’t have the u bolts installed in the mounting bracket. When you install the mast with a 2.5 inch OD tube, this is the “max” this mount can fit around. It is FAR easier to leave the mast out of the brackets, install the brackets right and make them truly level, than attaching them to a mast first and trying to eye ball it. When the brackets are fully installed, putting the mast in the “V” of the brackets, putting in the u bolt in the top bracket (u bolt plate is optional) first, thread on one of the two nuts on one side of the u bolt by only a half turn. Then thread in the other side. This can be very difficult with one person holding a mast and trying to do this at the same time so be sure to have a buddy and do this all slowly and deliberately. Once the top bracket u bolt is threaded, proceed to the bottom bracket. I was able to use the optional u bolt bracket on the top bracket, but not the bottom bracket. I needed to test fit these first on the ground, which I did not do, and the difference was the installation of that third leg. What I needed to do was to loosen the two connecting bolts, which would have allowed that little additional room I would have needed to get it to fit, but I just proceeded without that additional bracket.
With the mast mast installed, you need to be sure to pay attention to your “stop points” discussed earlier. This will ensure the best chance for success for this mast to stay up there! The best part of the “Black” mast is that it mostly disappears into any background and at night you cant see it at all.
Article on assembling the MK-8-HD (be sure to use the adjusted marking locations as discussed above) MK-8-HD ASSEMBLY
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