: OTA Mounts, Towers, Rigging Hardware
Hey everyone. I'm thinking of extending my antenna as I think it's a little too low from the chimney install I have and I was wondering what people thought of using some kind of PVC tubing for the mast instead of an aluminum pole? I currently have a 5ft aluminum pole that I got from S&R when I bought a kit there last year. I passed by Home Depot this weekend and saw the 10ft aluminum poles but was kind of surprised at how heavy it was hence why I thought a PVC kind of mast might be easier to handle up there. BTW, this was a 1" 10ft pole.
2012-05-06, 10:24 PM
At best, a PVC mast would sway in a strong wind, causing signal problems. It will probably snap off in the first big southwestern Ontario thunderstorm that rolls through.
2012-05-07, 03:31 AM
Lobo, do not use PVC or ABS. As I've been telling people for many years, go to a store that has 10' lengths of any plastic tubing, grab one and give it a good shake. Now do the same with extruded metal pipe and you'll see a world of difference in the rigidity.
So, given that distant ATSC signals do not like a vibrating antenna at the receiver end it is plain to see that you do not want some sort of limp spaghetti holding up your wonderful antenna. Go with solid metal or don't do it at all. ;)
2012-05-07, 10:46 AM
"covenants or title restrictions"
If you mean by-laws in the city of Markham,
No, restrictive covenants (http://en.wikipedia.org/wiki/Restrictive_covenant) are set by the developer of the community to create and protect an atmosphere for the community. They are part of the contract you signed when you bought the property and part of your deed. The only way around them is to have them prohibited at a political level (for example some provinces have banned covenants (and bi-laws) that prohibit clotheslines).
2012-05-07, 10:53 AM
The highest you can safely go with most tripod roof setups is about 5'.
That depends on the size of tripod being used. What you are saying is true for a 3 foot tripod, but a 5 foot tripod (such as the CM-9004) can handle a 10 foot mast without guy-wires.
Thanks stampeder! I'll go for the steel.
2012-05-13, 01:04 PM
There is an old tower that has frozen bolts that I want to loosen so that I can disasseble the 3 ten foot sections and take a closer look at them and clean them up. Are there any suggestions for doing this other than using wd40 regularly over a period of days and tapping them to try to disengage them. Also, if I wanted to clean them up (the 10 foot pieces are a bit rusty), are there any recommendations? Sorry if this is the wrong place.
2012-05-13, 06:10 PM
I've used a pipe extension on my ratchet as a "force multiplier". This usually does the trick.
2012-05-13, 09:32 PM
The other thing you need to be aware of is the load limitation for your particular tower installation. A DMX tower will have a maximum of 3 square feet of wind surface area for the antenna you place at the top. If you desire to increase this figure, you will need to guy your free standing DMX tower.
2012-05-14, 12:53 AM
The highest priority for me is the internet. I will have to make my tower decision after the installer comes out for another attempt at getting a signal on Wednesday.
I'm keeping my fingers crossed that I might be able to get away with a roof mounted 10 foot mast and tripod to put me approximately 30 feet AGL, but all my calculations suggest I need at least 40 feet to clear the trees surrounding me for LOS to the ISP's tower.
If I can even get a suboptimal but usable signal for my internet with the trees now filling in, I'll do some figuring on surface area after I see how big a device I am left with.
If I was to combine the CPE and an 8 bay bow tie antenna on the same tower, could I factor in that the CPE would be pointing into the prevailing NW wind for the largest percentage of the year, with the bowtie across the prevailing winds aimed generally NE?
If the wind load turned out to be too much of a concern I would likely not include an OTA antenna on the tower.
2012-05-14, 12:59 AM
roger1818, but that 10' mast on a 5' tripod will have about 3' within the tripod itself...only netting an elevation of about 7'--less if the tripod legs are mounted below roof peak, which they typically are. Even then, I'd be hesitant to put a large antenna on it, such as an 8 bay, or 8-bay and vhf combo.
2012-05-14, 01:06 AM
envirogeek, I'd be hesitant to vary accounting of wind load of antenna equipment by factoring the direction of prevailing winds relative to antenna direction.
I hope that made sense?
Wind load is wind load.
Most WISPs operate at high frequency, so LOS would definitely be necessary. And the antenna is typically smaller...thus minimum load.
I plan on bolting a 3 ft tripod to 2 - 2x6 pressure treated boards, on a flat roof. The antenna is a CM4228, on a 7 ft mast in the tripod. I plan on "shimmming" up one leg since the roof actually slopes down, inward to the middle for the drain. The roof is newly installed membrane (looks likelong strips of shingle material) which I assume covers a real welded membrane...)
In any case I intend on placing some sort of rubber mat under the wood. I plan on using about 10-11 12"x12"x1" patio blocks over the wood as weights. This about 250 lbs.
I am not sure if this is TOO much weight, possibly damaging the roof membrane ? and Im not sure if rubber mat is correct material to place underr boards ?
I do also plan on using a 3-guy wire system to stabilize the mast...
Any comment is appreciated, thanks
(And, Yes, I did search the other threads regarding this, but no specific answer was found)
2012-05-14, 09:28 AM
As a sailor I'm thinking of wind load as windage and weight aloft. Given as a value in square feet my first response is to picture the surface being acted upon. I would kind of expect wind load for devices aloft to be given in cubic feet and/or weight.
The Zyxel unit the first installer brought out was probably no more than 1 square foot. The first location we tried in January was definitely trying to shoot through some trees. I think I have one possible location on my roof that will work, otherwise it's tower time...
I greatly appreciate the responses from yourself and Gentleman. I will take them into account and report back later this week.
2012-05-14, 03:23 PM
firefilmoon, Disassembling Tower - frozen bolts and nuts
You might want to try a nut breaker, since you'll be replacing them anyway when you re-erect.
2012-05-14, 04:51 PM
roger1818, but that 10' mast on a 5' tripod will have about 3' within the tripod itself...only netting an elevation of about 7'--less if the tripod legs are mounted below roof peak, which they typically are.
I assume you are replying to post #1785 (http://www.digitalhome.ca/forum/showthread.php?p=1412054#post1412054).
Given that argument (if for some reason you want to ignore the elevation gained by the tripod itself), a 5' mast on a 3' tripod will have about 2' within the tripod itself...only netting an elevation of about 3', so the the the 5' tripod with a 10' mast I suggested will give you more than twice the elevation (you need to compare apples with apples). If you need more elevation than that, either guy the mast or go with a tower.
Even then, I'd be hesitant to put a large antenna on it, such as an 8 bay, or 8-bay and vhf combo.
As long as you don't use with more than a 10' mast on a 5' tripod, I don't see it being a problem using an 8-bay antenna (the rule of thumb is about 1/3 of the mast needs to be within the tripod since leverage is all about ratios). I do agree that if you want to use both an 8-bay and a big VHF (2-13) antenna, that may be a bit much, (though a small VHF-HI antenna should be okay with an 8-bay).
2012-05-14, 07:15 PM
Thanks for the ideas - I think Dirtroad's nutbreaker is what I'll do...since the nuts and bolts are toast anyway
2012-05-15, 11:00 AM
^^^Just make sure you replace them with the exact type recommended by the tower manufacturer. Wade sells replacement nuts/bolt kits for their towers.
2012-05-15, 09:09 PM
How do I figure out what kind of antenna it is - I didn't see markings. Would photos help idetify it - although it looks quite rusty but feels stronger than it looks. I have photos if that could be used to identify it - and whether it is worth keeping
well the pictures are in my profile - probably not salvageable but maybe there is something that can be done to bring the thing back to life!
2012-05-29, 09:41 PM
(i hope this is the right forum -- can't see where else i should post this question)
a few surprises delayed my plans, but now i'm about to install that j-mount on my roof (stm-1000 from a-d), to support a db8. i have built a base into which the j-mount will bolt into (see included picture) and wanted to confirm with others that it is sturdy enough.
using the foot of the stm-1000 as a guide, i have marked the spots where the lag bolts will be (obviously screwed from the outside) to make sure this assembly was big enough. i will use a fine+long bit to drill outwards from the inside to have guide holes visible from the outside, which i will then use to drill the required holes for the lag bolts.
(i've pointed to the 4 "guide spots" with arrows)
as you can see, the base is just 5 lengths of 2x4 grouped between two roof trusses. they are attached to the trusses using 3 inch wood screws, with some pl premium between them to make sure they don't twist/bend due to heat & humidity.
so, does this pass muster?
thanks in advance!