Aligning to Astra 28.2° East: the values for your city

1What the three numbers mean

Azimuth is the compass direction the dish points in, measured from north through east. In the British Isles it comes out around 140 to 146 degrees for Astra 28.2 — well round to the south-east, not due south as many expect.

Elevation is the angle above the horizon. For Astra 28.2 it runs between about 21 degrees in Scotland and Ireland and 25 degrees in the south of England. That is flat — flatter than most people expect — and it is exactly why a single tree can block reception.

Skew is the rotation of the LNB in its holder. It makes the two receiving probes inside the LNB match the horizontally and vertically polarised waves from the satellite. Without it the installation still works in fair weather — and drops one plane at the first rain.

2The values for your city

The table shows azimuth, elevation and LNB skew for several cities. All values are computed with the same formulas SatFinder uses and refer to the city centre.

The azimuth here is a true value. If you are working with a compass you have to apply the magnetic declination to it — currently around one degree west across the British Isles, which is small but not nothing. On an 80 cm dish with roughly two degrees of beamwidth, every degree counts.

3How the values spread across the country

The numbers move in two directions, and both follow a simple rule. The further south you live, the higher the satellite sits: Manchester needs about 23 degrees of elevation, London around 25. Across the country the spread is only a few degrees.

Azimuth follows the east-west axis. The further west you stand, the further round from south the satellite lies — Dublin points at 139.5 degrees, London at 145.4. And the skew is large everywhere here, between 14 and 15 degrees, because the whole of these islands lies far west of 28.2° East.

In practice: between two neighbouring towns little changes, between Dublin and London a fair amount. Take the value for a city 300 kilometres away and you are already outside the usable window.

4From the table value to a mounted dish

Set elevation first, because it is the only one of the three you can set exactly without a signal. Use the degree scale on the mount, not the back of the reflector.

This is where most self-installations come unstuck: on an offset dish the reflector stands considerably steeper than the elevation, because the offset angle of the reflector is added — 20 to 27 degrees depending on the model. At 25 degrees of elevation and 24 degrees of offset the reflector stands at 49 degrees. The scale on the mount, by contrast, already refers to elevation and simply reads 25.

Then azimuth: loosen the mast clamp only enough that the dish turns with effort, and sweep slowly — about one degree every two seconds. Finally the skew at the LNB. Tighten everything hand-tight, check the values again, then tighten properly.

5If your town is not in the table

The values change continuously with coordinates, so there are no jumps. Between two cities you can interpolate linearly: if your place lies halfway, take the mean. That works very well for elevation, usably for azimuth, and for skew too.

An example: Leeds lies roughly between Manchester and Newcastle. Elevation therefore around 22 to 23 degrees, azimuth around 144. That puts you safely inside the catch range, and fine-tuning does the rest.

What you should not do: take a value from a city in another country, or use a table for a different satellite. Both put you out by orders of magnitude, not by fractions of a degree.

6Why a calculated value beats any table

A table refers to the city centre. But large cities are twenty kilometres across, and the edge already differs noticeably from the middle. On top of that, values from different sources are computed for slightly different satellite positions — Astra does not sit at exactly 28.20 degrees but drifts within its station-keeping box.

SatFinder computes azimuth, elevation and skew for your actual coordinates, gives the azimuth in magnetic form as well and takes the declination from the World Magnetic Model. That removes the conversion step at which most mistakes happen up at the mast.

And wherever your values come from: the last tenths of a degree always come from signal quality, never from the number. The table gets you into the catch range — tuning in is still your job.