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Aligning Sky Dish to 19.2°E

kaku

Standard Member
My set-up:

- Sky Mini Dish (from my previous sky subscription)
- Humax FOXSATHD (single tuner)
- Sky+ HD Box (single cable connected from LNB)
- Bog-standard LNB which is used for Sky+ installation (2 cables coming out of it)
- The Sky+ HD box and FOXSATHD are connected to each of the cables coming out of the LNB and I get good signal from 28.2°E


I have tried quite a lot, but I am unable to align the mini dish to 19.2°E successfully.

- I moved the mini-dish slightly to the right for 19.2°E, but I don't know if I have to tilt the dish slightly upwards or just turn the LNB clockwise or counter-clockwise.
- The mini-dish seems to be having very minimal provision for moving the LNB up or down.

I can't get my head around to this and now don't know how I can adjust the LNB or the dish vertically to get some signal from 19.2.

I have gone into the hidden menu for FOXSATHD and can add Astra 19.2°E as well, but the signal/quality stays at 0% no matter what I do.
 

kevkbuk

Distinguished Member
Dish needs to come to the right and slightly tilted upwards from 28.2E, the LNB skew will be different but you should find something without changing it to perfect the signal. Check the receiver is checking for signal on a transponder that is in active use.
 

kaku

Standard Member
Dish needs to come to the right and slightly tilted upwards from 28.2E, the LNB skew will be different but you should find something without changing it to perfect the signal. Check the receiver is checking for signal on a transponder that is in active use.

I have tried changing the transponder to 12.480 V 27500 3/4, but I still don't see any signal.

Regarding the transponders, I am a bit confused with Humax FOXSATHD:

- In Set-up->Satellite settings - I can select individual satellites from a list and then select a specific transponder from another list.
- In Set-up->Manual tuning - I can select a satellite and then can set the transponder to 'All'. I tried the manual tune with this setting but no luck :confused:
 

logiciel

Moderator
Simply rotating the dish to the right as seen from behind it should be enough without any adjustments to the LNB.
 

kaku

Standard Member
I have tried a lot again, but with no success. With Humax FOXSATHD's set-up menu open which shows signal strength and quality, I tried moving the dish(initially aligned to 28.2) towards right hand side(standing at the back of the dish). I moved the dish slowly and with only slight increments and waiting for a few minutes for the box to lock to the satellite - each time using the 'shout through the window' method, but the signal strength and quality were 0% all the time. I then tried moving it back again (towards left hand side standing at the back of the dish). Moving backwards I could easily get the 28.2E signal back now with around 90% signal strength. I continued moving the dish towards left in the hope of finding any other satellite, but no luck again - the signal/quality stays at 0%.

I am also confused with the pictures of a multi LNB set-up where the 28.2E LNB is towards the right (standing at the back of the dish) and the 19.2E LNB is at the left followed by the 13E LNB. According to these pictures, should I not be moving the dish towards left starting from the 28.2 position(standing at the back of the dish)?
 

kevkbuk

Distinguished Member
It only takes a few seconds for the onscreen meter to update but the shouting through the window method can be rather frustrating, If possible get the TV outside so you can see it or use a signal meter, then you can swing the dish around and it'll beep when it finds something, you can then use the Foxsat meter to fine tune it.

Also try dishpointer.com to confirm where 19.2 is in relation to your property and to check for possible obstacles. With an offset LNB setup the offset signals hit the dish off centre so are reflected to the opposite side of the LNB arm from which they came. So if sat comes from the right the LNB has to be on the left.
 

Vin Blanc

Established Member
You continually speak of azimuth adjustment but no mention of adjusting the elevation?

From my location Astra 1N requires 25.4˚ of elevation where as 19.2˚ E requires 28.6˚ of elevation.

Which means that 19.2˚ E is approx. 3˚ higher in the sky than 28.2˚ E.

True to say that the skew setting is not mega critical but azimuth and elevation are!

Somewhere, I recall, you said that your dish may be the “cassegrain” (prime focus) type.

To confirm, here is a picture of a www.satelliteforcaravans.co.uk/elevation (Item 4) using a marine compass to set the azimuth according to Dishpointer.com.

Vin Blanc
 
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logiciel

Moderator
According to these pictures, should I not be moving the dish towards left starting from the 28.2 position(standing at the back of the dish)?
No, as kevkbuk says, the signal reflects from the opposite side of the dish.
VB: This is a "Sky Mini Dish" - to what extent should those 3 degrees of the satellite be reflected in its position?
 

logiciel

Moderator
Do "Sky mini dishes" have an elevation scale?
 

logiciel

Moderator
I thought the "engineers";) just put them up the way the one next door is.:D
 
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Vin Blanc

Established Member
Perhaps everyone involved should be aware that the OP is also running this very same thread on the “Digital Spy” forum?

This what he posted yesterday and which led me to post a link to a cassegrain dish picture.

Unfortunately, I confused which forum he had made the following statement:-

Quote;
“The pics from google suggest that I have a Cassegrain type dish.”
Unquote:

Obviously this is not the case.

For your info Logi, many “mobile” type dishes have an elevation scale stamped on the mounting bracket.

From my experience, even being one degree out will result in “no signal”. Perhaps some “anorak” would be able to calculate by how many miles a 3° error would miss the desired satellite some 24000 miles distant?

Personally, I think now that the OP should invest in a cheap Sat meter and read up on how to aim a sat dish.

Vin Blanc
 

kevkbuk

Distinguished Member
Perhaps everyone involved should be aware that the OP is also running this very same thread on the “Digital Spy” forum?

This what he posted yesterday and which led me to post a link to a cassegrain dish picture.

I've no idea where the cassegrain confusion came in, if the OP is using a Sky Minidish as they posted on both forums they do not have one.

The bottom line is the elevation must be changed via the dish bracket to tilt the dish upwards slightly and finding the sat will be easier if you can see a TV or have a meter rather than using the shouting method. It's good to see that both forums have more or less come to the same conclusion.
 

ant_thomas

Established Member
Vin Blanc said:
From my experience, even being one degree out will result in “no signal”. Perhaps some “anorak” would be able to calculate by how many miles a 3° error would miss the desired satellite some 24000 miles distant?

Whilst that does make perfect sense and you are probably correct I have managed to move a dish through various positions to pickup 28.2...23.5...19.2...13.0 perfectly fine without changing the elevation angle by quite simply loosening the bolts on the pole mount and turning it.
 

logiciel

Moderator
Either that needed a smiley or you haven't seen my many posts on the subject - I left out the quote marks.:laugh:
 

Vin Blanc

Established Member
From my experience, even being one degree out will result in “no signal”. Perhaps some “anorak” would be able to calculate by how many miles a 3° error would miss the desired satellite some 24000 miles distant?

Vin Blanc

As no one has even attempted to answer my question, I have now tried to answer it as best I can using my own basic "schoolboy" mathematics.

Dishpointer .com tells us that 19.2˚ E is approx. 39,000km distant (at least from my back garden).

A error in elevation would result (according to my calculation) in missing the satellite by about 975 km,
say 600 miles!

If this figure is even roughly correct, I would strongly advise the O.P. never to enlist in the army as a sniper! :D :laugh:

Vin Blanc
 

pedro2000uk

Distinguished Member
....

A error in elevation would result (according to my calculation) in missing the satellite by about 975 km,
say 600 miles! ..

It's better to calculate at the dish end - the dish size & it's acceptance angle, the focus & the waveguide size it has to 'get in'- c. 18mm @ KU & the power of the satellite.

If the dish has a 3 degree acceptance angle for example, then you should still receive from a strong satellite up to 1.5 degrees off until it drops too low. If you nudge a motorised off a strong sat like 19.2e, it'll carry on receiving about that - the bigger dish, the narrower the acceptance angle but then there's more power, so the cut off angle can be bigger with that increase in power.
 

ant_thomas

Established Member
MartinPickering said:
I didn't follow that at all. With a DiSEqC motor there's very little power because it takes it from the LNB supply.

He's not talking about the power provided by the receiver down the coax to the motor and LNB.

He means the power of the signal from the Satellite.
 

MartinPickering

Prominent Member
Oh, you mean in relation to the "EIRP"? (Effective Isotropic Radiated Power), which is a measure of the transmission power of a given transponder.

What do you think Pedro means by this?
If you nudge a motorised off a strong sat like 19.2e, it'll carry on receiving about that
About what?

the bigger dish, the narrower the acceptance angle but then there's more power
Really? For a given transponder signal, received at a specific location, the EIRP remains the same, regardless of dish size. However, the signal strength received by the dish depends on the dish size.
 
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pedro2000uk

Distinguished Member
The acceptance angle is smaller, so is the cut off angle.

Beamwidths are not quoted as absolutes (most such specs' aren't) but linked to a theoretical constant (of power from the satellite- EIRP if you like)... on a larger dish on an already powerful satellite, that can easily be exceeded, coupled with a high performing lnb & sensitive receiver, the cut off point is easily bigger than that quoted in the specs' & very easily proven in the horizontal by nudging off a satellite's position with a motorised system (& in the vertical if you have an inclined actuator). Similarly, a weaker satellite (in a given area) will have a narrower cut off angle than that stated in the specs.

I do avoid referring to EIRP (Effective Isotropic Radiated Power) footprints claims, they are so often wrong I do prefer verified power levels in a given area - according to some official footprints you require a 2m-4m dishes where we use as small as 80cm.


EDIT .. plus there is another cut off point btw- some people stop reading after seeing "EIRP/ Effective Isotropic Radiated Power" when all it refers to is 'claimed' signal power in an area.. similar to mobile phone coverage maps & we all know how good they are ..
 
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