Dish positioning advice

[redoxide]

Hi again i was hoping you might be able to help with a little advice on helping me reposition my motorised dish. I live in an end terrace house which is roughly positioned on a north south line. At the moment my dish is living in my garden attached to a nice sturdy fence post (not ideal i know but it has done the job till now). But because of its position i can only see satellites in the east which is ok but being the sort of person i am i'd hate to think im missing out on anything in the west .So i have decided its time to move the dish to a more suitable position up higher. i have attached a little drawing of the options i have regarding positioning of the dish and ideally i would like to keep it hidden from sight from the front of the house so to me position B or C would be best but would i get the full arc from either of those positions or would the dish need to clear the ridge of the roof as in position D?

Any advice would be most appreciated thanks in advance, Red

[Robbo]

From the exposure to the wind point of view, you want it to be as low as you can.

I think C and D are too high.

Somewhere around B looks best.

Depending on the slope of the roof you may well get a good part of the western arc.
A bit of trigonometry is required here. Or up the ladder with an inclinometer.
40-50 degrees azimuth either way is usually enough. Not sure if theres anything decent past
30W, as my situation is just like yours, but I'm not going up a ladder to change it.

That B bracket looks it bit dodgy though as its a bendy 'L' shaped one.


Alternatively, can you move the dish further east down your garden?

[BGonaSTICK]

I'd say between 'B' and 'C'.

I'd have the mast roughly where 'C' is but the dish lower down on it.

Once it's up and working, you can then slide the mast downwards in the T&K until you lose reception at an extreme westerly satellite, then just push it up slightly again. Then you know it's as low as possible.

I'd also have a lot more mast sticking out the bottom and the lower bracket as low as possible. I wouldn't put the top bracket too high either, as the top (triangular) part of the gable end isn't that strong.

[redoxide]

Thanks for the advice guys so you think i would be ok if the top edge of the dish was level with the ridge of the roof? that's good because then the dish couldn't be seen from the front of the house.

great stuff thanks again guys...

ps.sorry about the quality of my stylish artistic illustration

[Robbo]

Do you know the dimensions of the apex triangle at the end of your roof?

and What is your latitude amd longitude?

[redoxide]

latitude- 52° 4'10.N
longitude- 0°45'29.W

Not sure about the pitch / angle of roof im afraid :? , but its not particularly acute / steep.

Cheers , Red

[Robbo]

I was going to do a few calcs, but can't without the roof dimensions.

My house faces exactly like yours and I did a few for mine for the same type of position.
I was only going for 30W though. Anyway for my roof I calculated that I could have it near the bottom of the roof
to just get 30W. I ended up with a separate dish for 30W in the end, as I just didn't fancy the height.

[redoxide]

Thanks for all your help m8 i will get the tape measure out tomorrow and get back to you with the figures.

thanks again , Red

[Robbo]

Since we are talking about a north facing wall here, and you are virtually at 0 degrees long.

To work out the diagonal slope accross the roof this equation will do it.

effective slope accross roof= invtan(sin(sat azim) x tan(roof slope))

so if roof slope was 40 degrees and you wanted 30 W

the effective slope across roof = invtan (sin30 x tan 40)
=22.76 degrees.

if this angle is less than the required elevation of that sat from your location, the dish would theoretically see it ok from the bottom of the roof.


And accordingly, it doesn't matter how far up or down along the roof's slope the dish is mounted the view west will not be improved (
except if put near the apex).
What matters is the height of the dish above the roof's slope as Stick has suggested.