Could an aluminum pole be causing my problems?

[bobvick]

Sorry to start another thread. I am having nothing but problems with this 7.5 SAMI dish. I wish to god I had not got into this hobby, but I have too much money in the dish now to give up. I could not find a steel 3.5'' OD pole anywhere, so I ordered a 3.5'' schedule 40 aluminum pole from online metals. I buried it in cement and filled it with cement. I have not been able to get very many satellites to the west of my true south. So with help from here, this afternoon I got out and started working on the azimuth of the farthest west satellite I can get. Anyway to make a long story short, as long as the bolts on the mount are loose, especially the top two, I can get a good strong signal on SES3, like over 250 points of signal on the meter. As soon as I start to tighten the top two bolts, the signal goes down by half at least. All I can think is that the aluminum is so soft that the bolt is biting into it and it is making the dish move out too far, getting it off level. Could this be the problem? Do you reckon that if I sank even more money in getting a steel pole it would help?

 

[Lone Cloud]

How snug a fit is the mount on the pole? Is there play in it? If so, tightening the mount on the aluminum pole could essentially be throwing the thing off plumb. If there is space there, I would look at filling the gap - maybe wrapping the pole once with a piece of aluminum flashing. After it's tightened, can you flex the dish up and down, this way and that?

If so, you could also try taking note of which way your tightening is moving the dish, and starting by assuming that will happen - essentially making it go closer to the right spot when tightening it on.

It took me a long time to get my first signal back when I started. Now I can get it quick. Now I get no bills from useless cable companies

 

[Magic Static]

A few pictures might give a clue

 

[stone1150]

Tightening the bolts can be a hassle with any dish. I even had trouble with my mount until I took note of how the mount moved when tightening. This is where a little patience pays off. When you tighten the bolts, do so in a methodical sequence a little at at time working in a pattern with each bolt. Top, bottom, left, right. However your bolts are set. I have 4. 2 at the top at 90 degrees, and 2 at the bottom at 90 degrees. 4 total. Try to have the same amount of threads exposed on each bolt when done. As you tighten them, check the plumb with a level. Tighten them so the mount stays plunb. You don't need to tighten so much that the bolt stops. Just enough so as not to have any movement. Tightening too much can deform the pole where the bolts make contact. That can happen even with steel poles. Hope this helps. Have a great day!

 

[Phoxx]

Once you get an excellent signal, tighten the dish down, the, adjust you elevation, probably down. That should bring the dish back on track.

 

[bobvick]

Ok, thanks for all of your suggestions. I think I am going too tight. There is probably about a little less than 1/4 "play" in it. I checked the pole again this evening and it is 3.5" OD exactly. I tried wrapping some copper tape around it, but that seemed to make matters even worse when I set the dish back on. I couldn't get over a 50 or so on the meter with the tape around the pole. I went out and just tried to snug the bolts, maybe it is not moving any. In that way I was able to keep a stable signal on the meter. I will take some photos tomorrow and show you all what it looks like, perhaps that might help some. Thank you all very much.

 

[cracklincrotch]

Be advised that aluminum poles such as yours are quite flexible, especially in the wind, and even filled with concrete. Been there, done that, and have the tee shirt. My pole (at the time) held a 7.5 foot wineguard that weighed maybe 80lbs. It was 3.5" OD sched 40 aluminum and filled with concrete. That pole would deflect between 1" and 1-1/4" in winds, beginning at about 40mph and up. I would never, ever, do that again and could never recommend it to anyone. I would never had thought that with the concrete in that pole it would be so flexible, but it was. I should say though that the pole was four feet down and 8' out of the ground. And, the shorter the pole, the less deflection there will be.

I hope you don't have that experience with yours. It's a pain to replace.

 

[Blindowl1234]

Bobvick, I had an 8.5 foot Paraclipse dish on an aluminum pole a few years back. When I tightened the four bolts I noticed it was starting to put some nasty indentations in the pole. I think I finally ended up using it as a fixed dish. The pole I used was only about 1/8" thick maybe a little less than that. I thought later about pouring the pole full of concrete too. I'm guessing the pole you are using is a bit heavier duty than what I had though.
I sold that dish later and removed the pole. Blind

 

[Bongu]

A true schedule 40 pipe will have a wall thickness of nearly .25 inch. If steel, then it shouldn't deflect too much. Aluminium, will deflect much easier. A schedule 80 pipe should have wall thickness of nearly .30 inch, a better choice if aluminium is the only option.

Sent from my Timex Sinclair using SatelliteGuys

 

[shankle]

If I may add my 2 cents worth here.....
1st I would never use an aluminum pole.
If I had to do that for whatever reason, then before filling it with concrete I would put a 3/4" rebar in the
center of the pole and then fill it with concrete.

 

[FaT Air]

This is a subject I've "bitten my lip" on in the past. Let me explain, I don't think filling the poles with concrete helps stiffening up a pole. If concrete alone were the answer, bridge columns would be nothing but concrete. But they are not. they are engineered honeycombs of rebar and steel that provided the stiffness. The concrete only holds it all together. Concrete itself isn't that stiff, there's little additional shear strength in filling a pipe with concrete. Concrete is great for compression, but that's not the force involved. To stiffen a pole, I believe, requires the addition of something the's stiffer than the original pole. I'd use the largest round or square steel tubing, of sufficient stiffness, that would fit inside. Drill some holes along its length so the concrete that's vibrated down would flow thru the holes and "pin" the outer aluminum tube to the inner, added tubing. Here we have the concrete using it's greatest strength. Compression, between the inner and outer poles. (even sand would work, if tamped while it's poured in.)

 

[bobvick]

Well, I will use this one as long as it lasts, and I am able to get signal with it. If it starts to mess up, or I cant ever get the azimuth adjusted correctly, I will just get a steel pole and move the dish over to that. No big deal. I was just wondering if it could be causing the problem. But it seems like no matter what kind of pole you use, you still have to be very careful when you tighten down the bolts on the mount. Thanks for the help.

 

[Lone Cloud]

I have two poles on one end of my house, both with necessarily shallow footings, both going up through the eaves and a few feet above the roof. One is a 2 and a half inch pole carrying a one meter Winegard. The other is a three and a half, thin walled steel pole carrying my eight and a half foot solid Birdview.

Both are filled with concrete. I assumed, with the shallow footings, that adding mass to the pole would help with the resistance to wind torque. All I can say is, after five years and some heavy winds, nothing has twisted. I am certain that the initially wet concrete generates some rusting on the inside of the pole, all of which causes the concrete to bind well with the steel.

So based upon my own windy, shallow footing experience, dumping concrete down the pole adds strength to the system

 

[Magic Static]

I got to admit that filling my 21' x 4 1/2" pole with concrete did not make it as rigid as I thought it would. It still flexes some, easily. However, I think the pole would be insufficient itself without the fill. It takes about 30mph wind to make the 10' Winegard wiggle a bit.

 

[toucan-man]

My 6 1/2' tall pole has 1/2" wall thickness. Overkill - got it because it was cheap. If I recall the pole itself weighed 170Lbs for the total ten foot length. It is not perfectly rigid. If it were 21 feet above ground I expect it would flex quite a bit.

 

[FaT Air]

My theory for a tall pole and filling with concrete is it increases the Mass. Thereby decreasing the natural resonant frequency of the pole. This would also minimize the apparent movement by increasing the period of its movement. (swaying instead of shaking)
Here's how I first learned it: A long time ago there was an inch and quarter(or half) pipe running up the side of the house with the TV antenna on it. There was an eve mount and another attachment half way down the pipe. The antenna was about 5 ft above the eave mount. Anyway, whenever the wind was 10mph or more(which was often) this pipe would "sing" and as the wind increased it would get LOUD. I covered the top of the pipe thinking it was the open end acting like a flute. No change at all, still sung in the wind. Can't remember how the subject came up in shop but my shop teacher suggested filling the pipe with sand. Questioned about this, he said it needed mass, and to just try it. Well I hauled a sack of sand up on the roof along with a funnel. A second trip because my sack didn't hold enough to fill the pipe in one trip. Then covered it to keep the sand in and dry, and went inside and waited for the wind. And waited some more. Went outside and it was windy, but the pipe wasn't singing to let me know that it was windy. Well, what ya know, it worked.
A few years later our science teacher basically did a demonstration on the same principle. Thought I was well ahead on this but then we had to attempt to learn some of the math involved, I don't remember any of it. Just the decreases natural resonance part.

 

[bobvick]

Dish is working fine now. I am on the arc! I tightened the bolts down real good. I can get from 83 to 135 that I have confirmed that has most all I want. I thought the wind blew the dish out of alignment because I did not properly tighten the bolts down. When I went out and fixed the azimuth back (I had it marked) evidently I moved it just enough to get the western satellites good.

 

[stone1150]

A little time and patience usually pays off. That is great news Bob! Congrats! Have a great day!

 

[Lone Gunman]

Since I started messing with dish alignment I found that tightening the bolts can be the most difficult part to get right. What I wound up doing on both my 10 ft Winegard and my 7.5 SAMI was that a little WD40 squirted in the bolt holes will help a bunch, ie, the lube will aid in allowing "slightly tight" bolts to still move on the post. If/when you get close, lightly snug the bolts down then grab the outer edge of the dish and move it back and forth so the bolts clean off the area they are rubbing. With these bolts "slightly tight" some effort is required to move the dish but when you get ready to do the final tightening process there's little movement in the mount due to it being "slightly tight" to begin with. Works for me. ;-)

 

[bobvick]

I would like to thank everyone here for all of the help. I could not have got "on the arc" without all of you helping. I appreciate it very much. When I left for work this morning it was still working, maybe it will be when I get home I am getting around 70-75 on most transponders, even the DVB S2 ones. I guess the weakest that I have are on the NBC mux on AMC-18 they are around 65-70 but the picture is not jumpy or anything. I might could get a little better, but I am not messing with it, I can get all that I want so, it is good. I was very pleased to find some good channels that I had not seen in a while on Anik F1. I get great quality on those, up in the 80's.