question about pole mount...

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skinlab

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Jun 17, 2005
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Hi all. I'm getting a new directv install next week and due to my HOA, I'm restricted to how I can mount it. My thinking was a pole/mast mount in the back of my house that extends the dish up to/a little below the roof line. I don't want to extend PAST the roof line though. Is this viable? Do you think I'll still be able to get a signal a little below the roofline? My zip is 10512 and my elevation is supposed to be 29.7 Thanks.
 
Determine the pitch of your roof. If it is equal to or flatter than 29degrees you can put the dish anywherexcept behind the chimney.
If it is steeper than 29 degrees it must be put close to the ridge to clear it. Measure from a point between the LNB and the top of the dish to aim at the ridge. Plane Geometry; parallel lines never meet and non parallel lines always do.
Consider a pole clamp. If there is a sturdy vent pipe on your back roof and the pitch is OK mount the pole clamp plumbed on the vent stack. You won't need the mast or the holes in the roof.

Joe
 
You will need to determine the angle at which the azmuth reading for the dish's line of sight intersects with the azmuth position of the ridgeline. You can do this using your deed survey map.

In your garage or anywhere you can, you need to construct a full size working model of your situation.

Then, you basically need to get ahold of either a round or elliptical dish (whichever one you will need) and set it to the correct elevation and tilt (in the case of an elliptical dish). Mounting the foot on a piece of plywood is a good idea.

Then, you need to position a mockup of the ridgeline in front of the dish. A light horizontal board on a camera tripod is good for this, since you will need to adjust it's elevation.

Using a satellite position calculator, get the elevation positions for 101, and if necessary (elliptical dish) 110 and 119.

Using an angle finder and strings, attach strings to the bottom edhe of the dish pan with tape. Then using the strings, determine the reflection angles between the dish and the lnb and the dish, attach the strings to the wall. Do this for three strings; one each for 101, 110 and 119, if you are using an elliptical dish.

Attach a string to the foot pivot of the dish mount and tape it to the top of the ridgeline mockup. Move the rigdeline mockup to the correct angle in relation to the dish's azmuth angle. Stretch the string out and make sure the angle on the string is the same as your roof pitch.

Move the ridheline mockup back and forth and up and down as necessary in relation to the dish, while maintaintaining the angle of the string at the angleof the roof pitch. This will determine how far back you can place the dish from the roof line. If the ridgeline mockup touches any string attached to the bottom of the dish, it will degrade your signal.

This sounds complicated, but this is the only sure way to determine, if you can clear the ridge to get line of sight.
 
I would try putting the dish on a pole or some sort of temporary tripod without the LNB attached and set it up (temporarily) where you think it would work. Make sure that the dish is pointed correctly! Then look through the arm like a rifle sight. If you can see over the ridgeline, you should be fine. If you can't see over the ridgeline, just move the pole mount to a point where you can. Once you've found the spot on the ground, mark it and bury the pole. Voila!

For a simple throw-away temp. mount you can use a piece of fence tubing that is sitting in a bucket of cement or sand.

I had to do this at an apartment where I had to shoot over a porch roof, and with a little trial and error it worked out for me.
 
cromag,

the angle that the arm points up is not the line of sight to the sats. the lnbs are angled back so it is a compound angle. the line to the sats is always higher than the arm elevation.
 
You can do a lot of geometric and engineering calculations, but building a mockup is the simplest assured method of making sure that you can set the dish below the roofline and still get an optimum signal and full line of sight.
 
sateck01 said:
cromag,

the angle that the arm points up is not the line of sight to the sats. the lnbs are angled back so it is a compound angle. the line to the sats is always higher than the arm elevation.


D"OH! You're right! I was remembering the days of a single LNB! STRIKE MY LAST POST PLEASE!!!!

Nice catch sateck.... Now on with our regularly scheduled insanity....
 
try calling a local retailer and asking them to come out for a sight survey and explain to them what you are trying to get accomplished. If the tech carries an inclinometer he should be able to tell you if it's at all possible to do without having to do any mock-ups or anything to your home.
 
Mike500 said:
You will need to determine the angle at which the azmuth reading for the dish's line of sight intersects with the azmuth position of the ridgeline. You can do this using your deed survey map.

In your garage or anywhere you can, you need to construct a full size working model of your situation.

Then, you basically need to get ahold of either a round or elliptical dish (whichever one you will need) and set it to the correct elevation and tilt (in the case of an elliptical dish). Mounting the foot on a piece of plywood is a good idea.

Then, you need to position a mockup of the ridgeline in front of the dish. A light horizontal board on a camera tripod is good for this, since you will need to adjust it's elevation.

Using a satellite position calculator, get the elevation positions for 101, and if necessary (elliptical dish) 110 and 119.

Using an angle finder and strings, attach strings to the bottom edhe of the dish pan with tape. Then using the strings, determine the reflection angles between the dish and the lnb and the dish, attach the strings to the wall. Do this for three strings; one each for 101, 110 and 119, if you are using an elliptical dish.

Attach a string to the foot pivot of the dish mount and tape it to the top of the ridgeline mockup. Move the rigdeline mockup to the correct angle in relation to the dish's azmuth angle. Stretch the string out and make sure the angle on the string is the same as your roof pitch.

Move the ridheline mockup back and forth and up and down as necessary in relation to the dish, while maintaintaining the angle of the string at the angleof the roof pitch. This will determine how far back you can place the dish from the roof line. If the ridgeline mockup touches any string attached to the bottom of the dish, it will degrade your signal.

This sounds complicated, but this is the only sure way to determine, if you can clear the ridge to get line of sight.
You make it sound easier than it is. I always take the cosine of the azmuth divided by the tangent squared of the roof pitch. If the result is less than zero, I call my supervisor.
 
cr0mag said:
D"OH! You're right! I was remembering the days of a single LNB! STRIKE MY LAST POST PLEASE!!!!

Nice catch sateck.... Now on with our regularly scheduled insanity....


cromag,

the 18 inch round was compound angle also.
 
sateck01 said:
cromag,

the 18 inch round was compound angle also.


I see what you mean, but IIRC, that was a sony reciever & dish and even the manual mentioned using the lnb arm as a rough guide. In my case, I used the bucket o' cement trick and kept moving the setup a little at a time until I heard the tones of the signal meter. I just used the lnb arm trick as a starting point, so to speak.

A site survey is always the best way to go though. Hell, I'm sure that you can get one for less than I spent on cement and buckets. :)
 
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