Sky Dish on pole above roof apex

[novice_steven]

There are dense tall trees on rising ground at the bottom of my garden which are in the line of sight for receiving freesat from sky. An independent installer has suggested that a pole on the gable-end of my house would need to protrude around 1.7m above the apex in order to get a decent signal. He has suggested using a 2.5 inch steel pole on widely-spaced T&K's. I've done web-searches on 2.5 inch steel satellite poles but can't find any sold (2 inch seems the standard max). Is his suggestion reasonable and safe ? Is 2.5 inch steel pole used for satellites ? Thanks for replies.

 

[satelliteman]

Welcome to the forum.

It seems you've been given good advice as have seen many at that height on much smaller masts. Can't see why a strong 2 inch steel wouldn't be upto the job., try our site sponsors.

Also check planning regulations for dish positioning.

 

[deleted]

2inch steel will do fine

 

[Robbo]

A decent 2 inch ally pole would be Ok too, it's only a little dish.

Though, anything that goes above the chimney pot (if any) is supposed to have planning permission.

 

[novice_steven]

Thanks for the replies.

So, is a 2.5 inch steel pole a bit of overkill ? Would it be safer in terms of failure of the pole ? But, what about its weight and stresses on the gable-end wall ? I'm guessing a 12 foot pole will be used, with about 6 foot above the apex, 2.5 foot from apex to top T bracket, 3 foot to the bottom K bracket and 6 inches beneath the K bracket. Does that seem reasonable ?

 

[satelliteman]

The brackets should be substantial to take up the weight and stresses. How they are installed and fixings used are just as important.

 

[Simba27]

See here for a picture of my 80cm dish on a 7 foot scaffold pole attached to my back chimney.

http://www.satellites.co.uk/forums/...al-satellite-installations/66298-my-dish.html

It was fine until a particularly bad storm. The dish acted like a sail and the pole literally crowbarred the chimney off the roof. The whole lot fell through the roof of my conservatory.

 

[Robbo]

I'm not surprised, looking at that photo. But is a good example why the ratios between the pole length above the brackets to the distance between them should be minimised. Also why a larger dish shouldn't generally put on a chimney.

 

[petediscrete]

Anything attached to your chimney is asking for trouble.I noticed the aerial attached to the other chimney.I had a similar setup about 15 years ago which destroyed my chimney and as it was a shared chimney stack my neighbours too.The insurance company would not cover the claim as it was a non standard fixture and I had not advised them of its installation.I noticed the height of the trees surrounding you and while I love trees as much as the next person, that height is crazy, bearing in mind it is around housing which blocks sunlight and the way weather patterns are worsening there is a danger that they could fall over on the houses during a storm.

 

[redout]

Just my take but a neighbour has a sky dish on a pole about 1.5m above his gutter and the thing has only gotten absolutely battered by the wind.

Its actually quite funny as the pole is now slanted over about 30/40 degrees - he should have just put the dish out front!

 

[deleted]

simba looking at your photo you would get as much height fixing to your gable end than the chimney, and a lot stronger and you would be slightly further back from the trees enhancing your signal

 

[Huevos]

An independent installer has suggested that a pole on the gable-end of my house would need to protrude around 1.7m above the apex in order to get a decent signal.

So what's going to happen next year when the tree is half a metre taller? Are you just going to add a section of mast every year?

 

[novice_steven]

Just my take but a neighbour has a sky dish on a pole about 1.5m above his gutter and the thing has only gotten absolutely battered by the wind.

Its actually quite funny as the pole is now slanted over about 30/40 degrees - he should have just put the dish out front!

Out of interest, what kind of fittings were used in this example ? and where was it fitted to ?

So what's going to happen next year when the tree is half a metre taller? Are you just going to add a section of mast every year?

I'll have had 1 years use so all is not lost, but do trees grow at the rate you indicate ? What is others experience ?

I'm not surprised, looking at that photo. But is a good example why the ratios between the pole length above the brackets to the distance between them should be minimised. Also why a larger dish shouldn't generally put on a chimney.

It's just occurred to me that perhaps I should try a different tack of enquiry : one of my main interests in Freesat from SKY is to get two free Chinese language channels : CCTV and Phoenix. This may not be the correct sub-forum, but is there another satellite from which I could pick up these two Channels but is significantly higher in the sky and doesn't need a very large dish ?

 

[petediscrete]

Yes and another consideration are trees that shed their leaves in winter.I installed my first ever dish in the winter.Perfect reception.Summer came along and my reception got steadily worse.It was only after much checking (pre Google) I realised that the leaves that were absent in the winter were causing the problem.Dishpointer is you man.It will tell all you need to know about clearance heights etc and yes those trees look and grow exactly like the type you would find in a forest.

 

[Huevos]

do trees grow at the rate you indicate ? What is others experience ?

Depends on the tree. For example a young maple grows at between 3 and 4 feet per year. Old trees are slower. I've got some olive trees in front of my dish and I just trimmed 18 inches off the top to get them back to where they were last year.

 

[novice_steven]

Yes and another consideration are trees that shed their leaves in winter.I installed my first ever dish in the winter.Perfect reception.Summer came along and my reception got steadily worse.It was only after much checking (pre Google) I realised that the leaves that were absent in the winter were causing the problem.Dishpointer is you man.It will tell all you need to know about clearance heights etc and yes those trees look and grow exactly like the type you would find in a forest.

I've tried Dishpointer, and I may not be using it correctly, but if I move the dish position from the apex of my house to the ground level in my garden or to the open street 20 metres or so further away from the trees, it continues to show precisely the same clearance height, which can't be true, can it ?

Depends on the tree. For example a young maple grows at between 3 and 4 feet per year. Old trees are slower. I've got some olive trees in front of my dish and I just trimmed 18 inches off the top to get them back to where they were last year.

I think they're old Goat Willows

 

[Huevos]

I've tried Dishpointer, and I may not be using it correctly, but if I move the dish position from the apex of my house to the ground level in my garden or to the open street 20 metres or so further away from the trees, it continues to show precisely the same clearance height, which can't be true, can it ?

Yes it is true. The clearance height is the height from ground level at the dish to ground level at the obstacle. If you raise the dish 10 metres the obstacle clearance will also gain 10 metres.

 

[novice_steven]

Yes it is true. The clearance height is the height from ground level at the dish to ground level at the obstacle. If you raise the dish 10 metres the obstacle clearance will also gain 10 metres.

Just so I'm very clear then : Dishpointer is giving the difference between the height of the land at the dish position and the height of the land at the obstacle ? And to find out whether or not an obstacle will obstruct line-of-sight, one then has to add the Dish height above ground level at the dish and subtract the obstacle height above ground level at the obstacle ? Is that correct ?

It's just occurred to me that perhaps I should try a different tack of enquiry : one of my main interests in Freesat from SKY is to get two free Chinese language channels : CCTV and Phoenix. This may not be the correct sub-forum, but is there another satellite from which I could pick up these two Channels but is significantly higher in the sky and doesn't need a very large dish ?

Anyone got any advice re this query ?

 

[Huevos]

If DP says 10 feet that means you must have no more than 10 feet height difference between dish and the object. For example, if the dish is at 8 feet the obstacle can be a maximum of 18 feet.

But all this measuring is a pain. All you need to do is look up from just under the dish and just over the lnb and that is where the dish is pointing. If you cant see sky the dish is obscured.

 

[novice_steven]

It's just occurred to me that perhaps I should try a different tack of enquiry : one of my main interests in Freesat from SKY is to get two free Chinese language channels : CCTV and Phoenix. This may not be the correct sub-forum, but is there another satellite from which I could pick up these two Channels but is significantly higher in the sky and doesn't need a very large dish ?

Can anyone help - is there a better sub-forum for this query and how do I cross-post it ? Thanks